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WO2009066011A2 - Surface processing method - Google Patents

Surface processing method Download PDF

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Publication number
WO2009066011A2
WO2009066011A2 PCT/FI2008/050677 FI2008050677W WO2009066011A2 WO 2009066011 A2 WO2009066011 A2 WO 2009066011A2 FI 2008050677 W FI2008050677 W FI 2008050677W WO 2009066011 A2 WO2009066011 A2 WO 2009066011A2
Authority
WO
WIPO (PCT)
Prior art keywords
target
plume
ablation
spot
spot area
Prior art date
Application number
PCT/FI2008/050677
Other languages
French (fr)
Other versions
WO2009066011A3 (en
Inventor
Vesa MYLLYMÄKI
Reijo Lappalainen
Original Assignee
Picodeon Ltd Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Picodeon Ltd Oy filed Critical Picodeon Ltd Oy
Publication of WO2009066011A2 publication Critical patent/WO2009066011A2/en
Publication of WO2009066011A3 publication Critical patent/WO2009066011A3/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/24—Vacuum evaporation
    • C23C14/28—Vacuum evaporation by wave energy or particle radiation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
    • B23K26/062—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam
    • B23K26/0622—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/08—Devices involving relative movement between laser beam and workpiece
    • B23K26/082—Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
    • B23K26/0821—Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head using multifaceted mirrors, e.g. polygonal mirror
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • B23K26/362—Laser etching
    • B23K26/364—Laser etching for making a groove or trench, e.g. for scribing a break initiation groove
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82B—NANOSTRUCTURES FORMED BY MANIPULATION OF INDIVIDUAL ATOMS, MOLECULES, OR LIMITED COLLECTIONS OF ATOMS OR MOLECULES AS DISCRETE UNITS; MANUFACTURE OR TREATMENT THEREOF
    • B82B3/00—Manufacture or treatment of nanostructures by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/54—Controlling or regulating the coating process

Definitions

  • the invention relates to ablation techniques in very general level, but more specifically to a method of making high quality plume.
  • the invention relates also to surface processing by ablation for achieving by ablation a smooth surface feature for the surface to be processed.
  • the invention relates also to use of the plume in a coating method.
  • the invention relates also to a method of making particles.
  • An improved methods are sought to provide for deposition of thin amorphous and structural films including the steps of sequentially evaporating small amounts of material to be deposited from a target of the material with each pulse of a laser irradiating the target, each pulse having an energy less than that required to evaporate sufficient of the material to result in a significant number of particles in the evaporated plume and depositing the evaporated material on a substrate to form a film.
  • the traditional methods of PLD-techniques are related to the repetition rates about tens of Hz, although also pico-second and femto-second laser pulses are known to be used at the repetition rates from few kHz- to hundreds of MHz as such, with very low pulse energy.
  • the particle production of the conventional PLD -methods are estimated via the released number of atoms to be in level of 1 O 19"20 # per pulse so being sufficient to yield 10 8 # micron sized particles.
  • the above mentioned patent publication maintains a drastic decrease in the particle number of micron sized particles down to 1 micron sized particle from the 10 11 atoms per pulse, such particles are far to large for a proper smooth surfaces on the substrates when coated.
  • the techniques used in PLD-in a conventional like manner also has the disadvantage, that even if the laser used for the ablation were an ps-laser, the repetition rates may be limited only to several tens of kHz, so influencing to the yield of the coating, if the problems of the quality of the plasma are not considered, or the unpredictability of the particle's size and the shape of the fragments.
  • the yield from the target into the plume is important to the various applications, in which the substrate is to be carved with a pattern and cut, but even more important to the applications in which the substrate is desired to be coated, with a particle free coating, optionally with a structure with certain sized particles on the surface, or when it is the particles that are being in the interest.
  • particle synthesis in controlled conditions requires particle free conditions to start with.
  • the method can be thus used in processing a target surface so that the processing leaves a smooth surface to the target surface that is being processed in a carving like action and/or cut according to the first aspect of the invention, with minimum particles or left-over fragments.
  • the first and second aspects of the invention can be applied in combination to surfaces that are processed in various combinations with carving, cutting and/or coating.
  • the plume can be made and used for controlled inorganic nano-particle formation via nucleation phenomena and/or condensation followed.
  • Embodiments of the invention are based on the notice, that especially in cold ablation, the yield to the plume as well as its quality can be kept very high, i.e. free of fragments in certain large particles sizes, for instance, above 1000 nm when, the energy of the beam pulse is distributed onto such a spot area on the target surface on which the pulse energy part at each point of the spot area is sufficient to slightly exceed the ablation threshold of the target material.
  • the ablation depth is controlled to be shallow and the plume formed from the spot area on which the ablation threshold is exceeded.
  • the pulse energy versus maximum area above ablation threshold at the spot area also yields the advantage that the ablation depth, from which the plume originates at the spot area, is very shallow, and thus fragment formation in the scale of conventional PLD -scale is avoided.
  • the spot area can be defined as the largest continuous spot area on the target, of which area comprises of the points at which the ablation threshold is exceeded as little as possible to maintain ablation throughout the spot area.
  • a method of producing high-quality ablation plume according to the invention is characterized in the characterizing part of an independent method claim thereof.
  • a coating method according to the invention is characterized in the characterizing part of such an independent method claim thereof.
  • a controlled particle making method according to the invention is characterized in the characterizing part of such an independent method claim thereof. Examples on other embodiments of the invention are shown in the dependent claims. Various embodiments of the invention are combinable in suitable part.
  • a method of producing high-quality ablation plume by processing a target, on a target body, with a pulsed laser beam radiation is comprising: selecting a spot area for a beam cross-section on the target to correspond the ablation threshold of the target material to being essentially exceeded throughout the spot area of which the plume is ablated by the pulsed beam radiation.
  • the size of the spot area can be selected accordingly to match as based on the exceeding criteria through out the area for the energy in each point of the spot area.
  • the spot as ablation spot is made to roam on the target surface, on an ablation path, which can be pre- determined by the respective movements of the scanner surface and the target to make the spot roam on the target body.
  • the method also comprises selecting pulse energy, for a pulse of a pulsed laser beam radiation, to be distributed on to a spot location at the target, and to exceed an ablation threshold fluence of the target material throughout the spot area.
  • the method also comprises defining the spot area via the energy to meet the ablation threshold of the target material by terms of fluence to be essentially exceeded throughout the spot area.
  • the method also comprises setting an optical path for directing said laser beam radiation to meet said spot area with said fluence.
  • the method also comprises scanning said pulsed laser beam radiation on the target surface for defining a location of the spot with said spot area to be ablated from the target surface.
  • the method also comprises ablating at the location of said spot, the material from the spot defined by said scanning, to an ablation depth with said pulsed laser beam into a plume.
  • the spot size is kept as large as possible to meet the ablating-enabling fluence inside the spot area region, slightly to exceed the ablation threshold.
  • the repetition rate can be in kHz range, advantageously in few hundreds of kHz to few MHz.
  • the yield to plume can be kept as large as possible, from the interior parts of the spot area, but also more uniform and particle free.
  • the surrounding region in which the pulse energy is not anymore slightly exceeding the ablating threshold, but instead equates, essentially equates or is just below the ablating threshold can be so kept relatively low in respect to the spot area.
  • the contribution of the surrounding region with the potential variations of quality can be kept low to the whole plume as whole.
  • the variations of the plume constituent velocities are expected to be smaller and thus the plume more uniform and predictable than in cases where the pulse energy is much higher on a small spot than the corresponding ablation threshold.
  • the spot is formed by an out-of-focus-beam-cone.
  • the smooth surface feature in the method is at least one of the following: a smooth carving path, a smooth cut line, a smooth pattern on the surface.
  • the scanning in the method is implemented in the method by a turbine scanner at least partly, i.e. the optical path comprises a scanner surface that is of a turbine scanner. So, the scanning speed can be very rapid and high repetition rates are gained within large purity and fine smoothness of the surface.
  • the scanning in the method can be implemented at least partly by a vibrating and/or mirror scanner.
  • a vibrating and/or mirror scanner are suitable in various applications, where the plume quality is not as critical as in those applications that are implemented to use turbine scanner and/or the yield is not so critically kept high.
  • the area of the spot size is defined in the method by a characteristic measure which is at least one of the following: ablation depth, a diameter of the spot area, a perimeter of the spot defined along a closed equal-energy-line of a spot, the volume of the material to be ablated and ablation depth.
  • the spot area is set to its characteristic size at the target for pulse energy that is larger than 0,5 ⁇ J for an individual pulse arriving to the target.
  • the spot area is set to its characteristic size for pulse energy that is larger than 5 ⁇ J for an individual pulse.
  • the spot area is set to its characteristic size for pulse energy that is larger than 10 ⁇ J for an individual pulse.
  • the spot area is set to its characteristic size for pulse energy that is larger than 50 ⁇ J for an individual pulse.
  • the spot area is set to its characteristic size for pulse energy that is larger than 100 ⁇ J for an individual pulse.
  • the spot area is set to its characteristic size for pulse energy that is larger than 200 ⁇ J for an individual pulse.
  • the spot area is set to its characteristic size for pulse energy that is larger than 500 ⁇ J for an individual pulse.
  • the spot area is set to its characteristic size for pulse energy that is less than 5000 ⁇ J for an individual pulse.
  • the spot area is set to its characteristic size for pulse energy that is less than 50 000 ⁇ J for an individual pulse.
  • the spot area is set to its characteristic size for pulse energy that is less than 500 000 ⁇ J for an individual pulse.
  • the spot area is set to its characteristic size for pulse energy that is less than 15 J for an individual pulse.
  • the pulse energy is spread over the spot to keep just above the ablation threshold.
  • the distributing of the energy can be made by the optics in the optical path leading from the radiation source to the target via scanner.
  • the heating of the target by an electrical heater or a beam can influence on the energy needed to exceed the ablation threshold.
  • the repetition rate of the pulses is larger than 20 kHz.
  • the repetition rate of the pulses is larger than 200 kHz.
  • the repetition rate of the pulses is larger than 2 MHz.
  • the repetition rate of the pulses is less than 10 MHz.
  • the repetition rate can be even lower down to kHz range or even lower, within the provision that the plume-yield from the spot area is comparable to that from a higher pulse rates, say, in MHz range for instance in cold ablation with a cold ablation laser.
  • the ablation depth is smaller than 500 nm, for an individual pulse arriving to the target.
  • the ablation depth is smaller than 50 nm, for an individual pulse arriving to the target.
  • the ablation depth is smaller than 5 nm, for an individual pulse arriving to the target.
  • the ablation depth is smaller than 1 nm, for an individual pulse arriving to the target.
  • the ablation depth is smaller than 0, nm, for an individual pulse arriving to the target.
  • the ablation depth is larger than 0,01 nm, for an individual pulse arriving to the target.
  • the ablation depth is larger than 1 nm, for an individual pulse arriving to the target.
  • the ablation depth is larger than 10 nm, for an individual pulse arriving to the target.
  • the ablation depth is larger than 100 nm, for an individual pulse arriving to the target.
  • the method of producing high-quality ablation plume can be used in a method of surface processing to make by ablation a smooth surface feature for the surface to be processed as a target on a target body, according to an embodiment of the invention.
  • the spot is defined by the beam cross-section being out of the focus on the target surface.
  • spot is formed on to the target that has a smaller ablation threshold as the scanner surface so facilitating a diverging, a conical-like geometry for the beam and the corresponding cross-section for the spot.
  • a coating method according to an embodiment of the invention is implemented so that the substrate to be coated in the method with a smooth coating comprises a method of surface processing according to an embodiment of the invention for achieving fine plume to be used for the smooth coating of the substrate.
  • the spot at the target can be further defined by the adhesion with the substrate in a coating method according to an embodiment of the invention. So a better quality surfaces can be optimized for the coating - substrate pair for the particular use.
  • the spot at the target can be further defined by the optimization criteria of particlelessness of the plume.
  • the plume can be optimized for the conditions that avoid particle formation.
  • the amount of the matter that can nucleate from its phase in the plume to a liquid or solid phase and so to form particles in the medium can be controlled by keeping the nucleation rate very low via the ablated material concentration in the plume, to correspond the conditions of constant temperature at the near saturation conditions.
  • the amount of the material in the plume generated by the method according to an embodiment of the invention is thus kept lower than the saturation vapour pressure corresponding matter in the plume conditions and thus the nucleation is not initiated in significant scale, practically not at all.
  • the method can be embodied for particle making applications within an expansion chamber. Expansion chamber is well known as such.
  • the coating method according to an embodiment of the invention yield a coated substrate surface that comprises less than a pinhole per 1 mm 2 , preferably less than one pinhole per 1 cm 2 , even more preferably a pinhole per 1 km 2 , but most preferably no pinholes at the surface on the substrate body to be coated.
  • the coating method according to an embodiment of the invention yield a coated substrate surface is coated in such a manner wherein the first 50 % of the product surface layer does not contain any particles having a diameter exceeding 1000 nm, preferably 100 nm and most preferably 30 nm.
  • the coating method according to an embodiment of the invention yield a coated substrate surface, wherein the average surface roughness of produced articulating surface layer is less than 100 nm as scanned from an area of 1 ⁇ m 2 with an Atomic Force Microscope (AFM).
  • AFM Atomic Force Microscope
  • particles can be made according to an embodiment of the invention in controlled conditions.
  • the method according to an embodiment of the invention can be used to form the plume, and the plume is so cooled in a cooling phase for cooling the plume in the medium for producing particles via a nucleation phenomena.
  • the nucleation phenomena in the method comprises at least one of the following:
  • the nucleated particles are grown by condensation of the material originating to the plume.
  • more plasma is inputted to the plume to replace the nucleated and/or condensed material so to maintaining said nucleation and/or condensation.
  • the plume is diluted for preventing aggregate formation, and/or the particle coalescence. The particles are collected from the medium.
  • the plume comprises of at least one of the following inorganic constituents of the plume: ions, plasma constituents, atoms, molecules, nano-particles smaller than 10 nm in size, nano-particles smaller than 40 nm in size, matter that has characteristic size in an intermediate range of the afore mentioned size.
  • the plume instead of plasma of inorganic alone can comprise organic matter in form of organic cells and/or their constituents to be ablated according to the first, second and/or third aspect of the invention.
  • the medium that is in contact with the target material can be liquid.
  • the liquid is arranged to receive the plume.
  • the plume can occur in a liquid and consequently the rapid cooling of the plume constituents can form particles into the liquid and further removed from the liquid.
  • Arranging the liquid input for pure liquid and output with the particles into the balance, a continuous process can be maintained as far as the target material is available.
  • Such an immersion related ablation may be interesting option also for removing cells from an organic target, into the liquid and arranging the liquid for further use with the cells.
  • the material in the plume comprises of inorganic constituents for forming a ceramic coating or ceramic-like coating.
  • the radiation source to be used within the method is a hot ablation laser source.
  • a laser source comprises at least one nanosecond laser.
  • the radiation source is a cold ablation laser source.
  • the laser source comprises at least one of the following: a pico-second laser, a femto-second laser and an atto-second laser.
  • the material in the plume comprises of organic cells and/or their constituents.
  • the effective depth of the heat pulse from a laser pulse hitting the surface of a material varies considerably between laser systems. This affected area is called the heat affected zone (HAZ).
  • the HAZ is substantially determined by the power and duration of the laser pulse.
  • a nanosecond pulse laser system typically produces pulse powers of about 5 MJ or more, whereas a pico-second laser system produces pulse powers of 1 to 10 ⁇ J. If the repetition frequency is the same, it is obvious that the HAZ of the pulse produced by the nanosecond laser system, with a power of over 1000 times higher, is significantly deeper than that of the pico-second pulse.
  • a significantly thinner ablated layer has a direct effect on the size of particles potentially coming loose from the surface, which is an advantage in so-called cold ablation methods.
  • Nano-sized particles usually will not cause major deposition damages, mainly holes when they hit the substrate.
  • fragments in the solid (also liquid, if present) phase are picked out by means of an electric field. This can be achieved using a collecting electric field and, on the other hand, keeping the target electrically charged so that fragments moving with a lower electrical mobility then the plume constituents can be directed away from the plume.
  • An aim of the invention is to introduce a method for coating the target to be coated more efficiently and with a higher-quality surface than what is known in the prior art at the priority date of the present application.
  • the aims of the invention are connected to the following objects enlisted below as follows:
  • a second object of the invention is to achieve at least a novel method and/or connected means for solving the problem how, by releasing high-quality plasma, there can be produced a fine and uniform cutting line to be utilized in a cold work method that removes material from a target as far as the ablation depth, so that the target to be worked does not form any fragments that could be mixed in the plasma, in other words the is pure, or said fragments, in case they exist, occur only scarcely and are smaller in size than said ablation depth, from where said plume is produced by ablating said target.
  • a third object of the invention is to achieve at least a novel method and/or connected means for solving the problem how to coat the surface of an area serving as a substrate by using high-quality plume that does not contain any particle-like fragments at all, in other words when the plume is pure, or when said fragments, in case they exist, occur only scarcely and are then smaller in size than said ablation depth from where said plume is produced by ablating said target, in other words how to coat the substrate surface by using pure plume that can be produced practically from any material.
  • a fourth object of the invention is to achieve at least a novel method and/or connected means for solving the problem how to create by means of high-quality plume a coating with good adhesion features for gripping the substrate, so that the wasting of kinetic energy in the particle-like fragments is reduced by restricting the occurrence of the fragments or by restricting their size to be smaller than the ablation depth.
  • the fragments do not create cool surfaces that could affect the homogeneity of the plume jet through the phenomena of nucleation and condensation.
  • the radiation energy is effectively transformed to plume energy, as the area affected by heating is minimized when using advantageously short radiation pulses, in other words pulses of the pico-second order or even shorter duration, and in between the pulses, there is applied a certain interval in between two successive pulses.
  • a fifth object of the invention is to achieve at least a novel method and/or connected means for solving the problem how to achieve a wide scanning width simultaneously with the quality of high-quality plume and a wide coating width for even large objects on an industrial scale.
  • a sixth object of the invention is to achieve at least a novel method and/or connected means for solving the problem how to achieve a high repetition frequency to be used in industrial-scale applications, in line with the above enlisted objects.
  • a seventh object of the invention is to achieve at least a novel method and/or connected means for solving the problem how to produce high-quality plume for coating surfaces and manufacturing products in line with the objects from first to sixth, but still save target material to be used in the coating steps for generating re- coatings/thin films of the same quality, where it is needed. It is yet another extra object of the invention to apply such methods and means in line with said first, second, third, fourth and/or fifth objects, for solving the problem as how to cold work and/or coat surfaces, in an appropriate line with respect to each suitable type of such products.
  • Fig 1 illustrates a particle producing according to an embodiment of the invention, in accordance to the plume producing method
  • Fig 2 illustrates a plume producing method according to an embodiment of the invention for producing high-quality ablation plume, and a coating method that utilises said method
  • Fig 3 illustrates an embodiment related to carving and grooving embodiment and/or coating method
  • Fig 4. illustrates an embodiment for making several coatings
  • Fig 5 illustrates scanning a beam onto a target according to an embodiment of the invention
  • Fig 6 illustrates utilisation of several sources for the pulsed radiation to be used in ablation plume formation
  • Fig 7. illustrates an example of scanning the spot area having a size of 40 ⁇ m and a scan line
  • Fig 8A and 8B illustrate advantages of an example according to an embodiment of the invention for the plume yield and quality.
  • a suitable pulse length for a target material is less than 30 ps to be counted as a short pulse.
  • pulses within the fs-scale duration in another embodiment or even as-scale (atto-second-) in a further embodiment can be used down to 0,05 as (atto-second).
  • the pitch between two successive pulses is equal or shorter than the pulse duration, but kept constant.
  • the pitch duration is longer than the pulse duration but kept constant. Constant pitch and/or pulse length makes the radiation source simpler and easier to manufacture as a laser source.
  • a pumped laser source can be arranged to have at least some intermittency for the pitch and/or the pulse duration achievable in the energization by using a plurality of pumping mechanisms timed intermittently or differently timed to yield intermittence and to make the pumping either optically and/or electrically embodied in suitable part.
  • Such an intermittent radiation can be used, for instance, if different material/structure of the ablation path is to be desired to the target.
  • the intermittently pulsed laser can be a pumping laser to be used to pump a power laser according to an embodiment, or the intermittently pulsed laser can be itself a power laser, that is pumped by several mechanisms.
  • the pulse characteristics of the radiation to be used for the ablation can comprise such features as the pulse power, pulse energy, pulse shape, pulse duration, pitch between two successive pulses, intermittence, pulse/pitch repetition rate of the pulses on the target, repetition rate of the pulses on the scanner, cover ratio of the pulses on the target and/or a combination thereof.
  • the cover ratio of the pulses can be defined by a ratio of the common area of two successive hit spots to the area of an arbitrary hit spot.
  • characteristic wavelength means a wavelength that originates to the laser source that is used for the ablating.
  • the laser source can have several polarization modes at the characteristic wavelength, from which a certain mode can be selected to be used in the ablation in one embodiment, but in another embodiment several modes and/or characteristic wavelengths can be used when associated to the suitable pulse characteristic or characteristics.
  • the radiation to be used is in the wavelength range from radio wavelengths down to ultraviolet wavelengths or even down to low energy x-ray wavelengths.
  • the wavelength of the radiation comprises monochromatic and coherent radiation component that has a wavelength of radio waves IR, UV, visible light. Also intermediate ranges can be applied in embodiments.
  • ablation path can be predefined, so as to be used for defining the order in which the material from the ablation target is to be ablated.
  • the ablation path can comprises a spot or to be a spot-like, for applications in which a dot ".” is to be formed on the ablation target.
  • the dot can be gap, cavity or an ablation-drilled hole, even through the ablation target piece from its one side to another, said dot having a shape derivable from the ablating radiation geometry.
  • the path comprises a line, which is thus a queue of the hit spots of the spot area on the target surface.
  • the hit spots are essentially or completely non- overlapping, the hit spots form a line along the surface on the ablation target surface, according to the radiation geometry of the pulsed laser beam to form the dots, is referred as a carving embodiment.
  • the hit spots are essentially at the same location for making a hole and/or cavity along the normal of the surface.
  • holes that define a direction with such an angle that is between a surface and its normal can be drilled according to an embodiment of the invention.
  • the overlapping of the hit spots are arranged to define the direction of the cavity.
  • the drilling may be made at least some part so that part of the radiation of the pulse goes through the plume.
  • the plume can be further ablated by another beam arranged to remove the plasma, or the ablated plume can be removed at least partly by electromagnetic means arranged to provide an electromagnetic field to interact with the charged plume particles in order to deflect the plume away from the incoming radiation pulses.
  • the ablation-originating plume is kept small so to be easily and quickly dismissed.
  • the pulse rate is adjusted to match to the intermittence of the drilling action time scale of proceeding drilling according to the time in which the plume is dismissed from the existing hole, i.e. the pitch between the pulse is getting longer during the proceeding drilling.
  • the pulse shape is chosen so that the laser pulse has a first pulse-part that has a first power level capable of ablating target material at the hit spot, and a second pulse-part that has a second power level, which is higher than said first power level so capable to compensate extinction of the plume.
  • a pulse can be advantageous in certain embodiments in which the carving and/or drilling should be made through the plume directed radiation pulses.
  • the ablation target can be in rest in respect to the laser source.
  • the ablation path on the ablating target is defined by a respective movement of the laser source and the target body.
  • the target is hold by a holder that is arranged to move the ablation target body so that its surface comprises at least partly the ablation path having the characteristic dimensions of the ablation path and the appropriate ablation depth in each defined location of the ablation path, as defined according to radiation geometry of the laser source.
  • a scanner is used to scan the target surface i.e. to allow the spot roam along a pre-determined path on the target.
  • the ablation target can be arranged to rotate so having the ablation path along the surface of said target. If the rotational movement is suitably constant and occurs around a fixed axis, an embodiment of the invention can be used for cutting the ablating target, as in turning machines and/or reamers. Also other carving-like actions can be arranged to occur in a similar way as in a turning machines and/or reamers.
  • the target piece can be placed on to a robot providing movements in an xy-plane, z-plane and/or at least one rotating movement so providing at least in theory access of the ablating beam to any visible surface location, for a carving action and/or cutting parts of the ablation target body.
  • the carving can be made in a low pressure that is however higher pressure than the pressure in outer interstellar free space, but lower than an atmospheric pressure. According to an embodiment of the invention the carving can be made in over pressure condition, and/or in a specific gas atmosphere for yielding protection against the diffusing plume materials to the parts that may be critical for the material.
  • the laser radiation geometry can be a beam, as approximated as a one-dimensional line from the source to scanning optics and further to the ablation target, so advantageous to be utilised in formation of ablation paths that have a breadth in order of ten or several tens of times or smaller breadth.
  • the laser radiation geometry can be as a fan of beams, as approximated as a two- dimensional plane from the source to scanning optics and further to the ablation target on which the fan causes a surface oriented line by one pulse shot, so defining an area to be carved on to the ablation target by several adjacent pulses.
  • the radiation geometry can be approximated as a cone that converges towards the target surface.
  • the spot area is formed by a cross section of the cone.
  • the cone from the scanner to target can be arranged diverging towards the target. This can be achieved for instance by the curvature of the scanner mirror surface to match to the desired geometry.
  • several fans of beams can be arranged to hit the ablation target simultaneously so defining an area by one pulse shot, provided that the power is sufficiently large to cause ablation at said area to the appropriate ablation depth of one pulse shot.
  • This can be also provided by a bunch of optical fibres and/or beam expanders with sufficient tolerance to tolerate high energy level of the laser.
  • the ablation target is kept in rest and the ablating radiation is directed via an optical path to the ablation target that is held still.
  • both the ablation target and the ablating radiation are to be moved in respect in each other, but also in respect to a virtual third party observer.
  • the method has also embodiments that are directed to destruction of enemy and/or the military material of such.
  • the working method embodied applicable as to weapons also long pulsed lasers can be used having the pulse duration over 80 ps, even up to micro second scale.
  • the fragments may be not the problem of the weapon user, and thus also the thermal transfer does not have a role to play, does a destroyed enemy, its material, vehicle and/or tank have smooth cut line or not.
  • the larger spot size can be used for more destruction.
  • cold-work lasers can be used also in disarmament of explosives, so cutting by ablation the detonating path from the ignition primer to the essential explosive material away, or by ablating critical parts of a bomb so to disarming it.
  • the explosive material is cut to smaller pieces to be removed so that if the ignition occurs, only the primer and/or a small amount of the explosive goes off. That is possible because the material structure of the explosive is not sufficient enough capable to relay the thermal transmission from the hit spot to the surrounding material.
  • the detonation speed can be in order of 10 km/s, may be much lower in reality, which shown estimate speed is quite slow in comparison to the actions that happen in the material between its structural parts.
  • the cold-work by ablation can be used in purification of materials, provided that the plume is to be handled as such, so as at least some of the constituents to be separated in suitable part from the other.
  • the material that is ablated from the ablating path is arranged to originate from such a target that has a material layer arranged to be used in coating by ablation, by placing and/or moving the body to be coated into the plume.
  • the ablating radiation is directed from the source to the working spot at the ablation target via an optical path, which can be embodied in one embodiment by a fibre based path in suitable part, but in another embodiment in suitable part in vacuum.
  • the path comprises a scanner arranged to scan the radiation to the working spot area on the ablation target.
  • the scanner is a turbine scanner, which has a rotatable structure arranged so that it comprises a first mirror surface part that is arranged to direct said radiation towards the working spot while another, a second mirror surface part of a previous location of the radiation spot on a mirror surface of the scanner is arranged to cool.
  • a scanner to be used is a known scanner as such.
  • geometry of the beam can be adjusted by a suitable beam expander where necessary to apply the scanned beam to a certain geometry to enlarge the hit spot to the spot area, provided that sufficient power for the ablation at the area is available to meet the ablation threshold throughout the spot area.
  • a prismatic-like but longer than a disk turbine scanner, in direction of the rotation axis length, can be used for radiation geometries that are arranged to provide a line oriented hit spot.
  • the mirrors comprise a curved surface part so arranged to deflect the ablation path at the ablation target in a certain repeatable way.
  • the curvature can be, as arranged in the plane of the scanner movement linear or rotation in respective embodiments, positive but according to another embodiment negative, as respectively defined by the distance of the nearest part of the mirror to the movement / rotation axis as being in minimum with the positive curvature and as maximum with the negative curvature.
  • the curvature can be arranged in the plane of the movement/rotation axis, i.e. in perpendicular to the movement/rotation defined plane.
  • multiple curvatures can be used in order to arrange a repeatable ablation path on the ablation target.
  • the scanner to be used comprises parts made of nano-tube material because of the tolerance against the forces in the movement.
  • the scanning surfaces of the scanner can be coated with carbo- nitride (CsN 4 ) for improved mechanical and/or thermal durability to tolerate high- energy pulses of the laser source.
  • ablation to be used in the cold work is made by a laser source radiating laser-radiation that has at least one characteristic wavelength.
  • single cavity can provide also harmonic waves with a different wavelength, but such may be not directly utilizable as such to the ablation according to an embodiment of the invention.
  • the laser source is selected for the cold-work so that its radiation is pulsed so that the pulses have duration that is shorter than 50 ns (nanoseconds), but according to an embodiment advantageous for a probability to cause less fragmentation of the ablation target at the spot area, has the pulse duration is shorter than 50 ps (picoseconds), but according a further advantageously for a probability to cause less fragmentation, shorter than 10 ps pulse duration.
  • the pulse length can be even shorter, as in one embodiment in the fs-range (femto-second) arranged to be used for the ablation along the ablation path.
  • a hot work ns-laser is used, but the scanning of a pulse is made so that the target experiences a cold-work ablation during the pulse because of the movement of the spot area on the target in motion.
  • Figure 1 illustrates an embodiment as a particle making method according to the invention.
  • the method related phases for the preparation and some details are omitted for clarity reasons.
  • a plume is made, formed from the target material according to an embodiment of the invention.
  • the plume is made so that there are no particles, or optionally if any particles were possible to be present, they are removed by a removal mechanism (not shown).
  • the plume with the plume constituents in a plasma and/or vapour phase are fed 102 into the reactor, which can be actually of any suitable type for particle nucleation and growth, for instance embodied as an expansion chamber.
  • the plasma constituents are allowed to cool 103 in the reactor so that the temperature is allowed to be decreased directly proportionally to the volume, while the exponential dependence of vapour pressure on the temperature is decreasing the saturation vapour pressure more rapidly so simultaneously increasing the saturation ratio.
  • the nucleation occurs 104 in a very short time scale, even in ⁇ s or so, depending however the conditions.
  • the particle size can still grow by condensation 105. The process can be maintained as long as the condensation favouring conditions allow the matter to condense on the particle surface.
  • the particles can be captured 106 by impinging, diffusion or scrubbing techniques or by electrical collection means. Also combinations of electrical means and scrubbing can be used to make a liquid suspension of the particles.
  • an appropriate plume material can be fed 107 into the zone of condensational growth in the reactor. So, even several layers can be made and the particle so produced could have finally an onion kind of structure, achieved by the several coating layers gained in the chain of condensation from various plumes produced by the method.
  • the particles can be collected in several ways as a skilled man knows about known collection mechanisms for the appropriate particle size.
  • Figure 2 illustrates a method 208 of producing high-quality ablation plume by processing a target, on a target body, with a pulsed laser beam radiation according to an embodiment of the invention.
  • the same method can be used for coating within the provision that the selected substrate 200 is coated 2007 with the plume material produced in the method phases 208.
  • the method 208 comprises selecting 201 the target to be used for in the ablation, and the selection of the target material is applied for the embodiments that use the coating for the coating.
  • the plume material is not necessarily used for the coating of the substrate, but can be even wasted, or collected for circulation.
  • the pulse energy is selected 202 for the ablation to match 203 the spot area to the maximum available in respect to exceed the ablation threshold sufficiently to have the plume and corresponding energy.
  • the optics of the equipment is set 204 for the spot area size.
  • the radiation, as pulsed, is scanned 205 on the target for the plume being formed from shallow ablation depth from the spot area by the ablation 206.
  • the plume material is used for the coating 207.
  • the coating can be repeated with the same or another coating from a different target material as many times as required for the desired product.
  • the figure 3 illustrates a carving/grooving like method utilisation to make mere working with the target forming the product or a pre phase of it.
  • the phase 302 in the method checks is the product ready after the phase 208. If the product is ready, and no more carving and/or coating were needed, the product is ready 301 and can be used or sold. According to the dashed lines, some products may still need a coating 207, although the carving was already made (the dashed Yes branch). Some products may need after a coating or few, further working to be made, illustrated by the dashed arrow from the coatings 207 to 208. As further patterns are to be made, the product may be not ready yet (No) and the further patterns 303 can made to the target or substrate. Is the product or substrate called as target or substrate depends on is it subject to the carving/grooving (target) or to coating (substrate). Thus, it is clear that a target can act as a substrate and vice versa.
  • Figure 4 illustrates a cold work method according to an embodiment of the invention.
  • the method has phase 6001 of selecting and/or exposing the target to be exposed to the radiation to ablate material along the ablation path on the target and the spot area therein.
  • a radiation beam is directed to the selected target material in phase 6002 in order to expose a target material to the radiation at the spot area.
  • the second ablation phase 6004 is not necessary a completely parallel phase, but can be a serial phase according to one embodiment.
  • the target can comprise a constituent of the coating, but part of the coating can be formed by the atmosphere at the substrate, and/or the substrate surface constituent or several constituents.
  • the target material is the same as the coating.
  • the coating phase 6005 can be used as an only coating phase according to one embodiment, but the second coating phase 6006 illustrates that in another embodiment there can be several phases of coating to coat the substrate several times, completely or in suitable part.
  • the carving and coating phases can alter so at least partly remove parts of the just made coating to the ablation depth. This can be achieved by making the target to the substrate and/or vice versa to achieve the desired layers for the application.
  • the method comprises a phase of checking if all the coating layers were already made. That is illustrated by the arrows directed as shown in figure backwards from higher reference numerated phases to the lower reference numerated phases.
  • the freedom to select of a coating 6011 for a phase 6003 and/or 6004, substrate 6010 and/or target material 6007 is illustrated by the periodic system of elements 6008, 6009.
  • the target material is ablated.
  • compounds of the elements can be used to be ablated.
  • organic material can be ablated, in order to form a coating thereof.
  • the body whose surface is to be carved, machined and/or coated by the cold-work according to an embodiment of the invention, said surface to be coated can be a surface of a body per se or an already coated surface, or a surface at least partly coated, optionally or in addition in suitable part, such a surface that is indicated in a patent document FI20060182, to be incorporated herein by reference.
  • Fig. 5 illustrates an operation of a scanner to be used in the radiation path according to an embodiment of the invention.
  • the scanner can have coated mirror surfaces with a high temperature tolerating reflective material, or totally manufactured from carbo-nitride and/or diamond in suitable part.
  • figure 5 shows a conventional turbine scanner, the figure is not limiting the scanner type only to turbine scanner. In certain applications also non-conical round mirror scanners and/or wobbling scanners can be used for the scan, but especially for slow repetition rates and very large spot areas the scanner surface can be also that of a mirror scanner or a vibrating scanner being embodied.
  • the radiation source 1600 (not shown in Fig 5, but demonstrated by the beam 1510) can be embodied as a laser source embodied according to diode-pump of PDAD-system or any other cold ablation capable laser, i.e. with sufficiently powered laser, preferably with 100 W or larger in total power and having pulse length of pico-second, femto-second, or atto-second, with an inter-pulse pitch, and a pulse repetition rate adjustable up to larger than 20 MHz, advantageously up to larger than 50 MHz.
  • the wavelength can be in the visible light region, but is not limited to that only. Although just one drawn, there can be also two or more radiation sources, operable in the same path in parallel or in series, which are not limited to the embodiment of similar source nor to that with all-different sources.
  • the radiation beam is reflected as a reflected beam 1503 via the scanner 1502 mirror surface to an optical lens 1501 , to the target 1400.
  • the target can have a smooth surface structure, roughened arbitrarily or so to have a certain surface structure optimized for the ablation and the coating formation, but in an embodiment in which the target is addressed to mere carving phase, the structure of the target may be unoptimized for the carving as such.
  • the ablation path provided by the hit spots at the target is illustrated by H and the related number to illustrate also the scan on the surface of the target along the ablation path at the numbered points of the path. So, the H1 defines a moment when the beam 1503P, which can be polarized to a certain polarization by its production and/or the optics 1501 is directed to the spot area during a scanner cycle.
  • polarization of the beam can be used for the ablation optimum at the ablation path on the target surface, especially, if the polarization can be used for certain selectiveness of the ablation during a scan.
  • the Fig. 5 demonstrate the scan points H1 , H2, H3, H4 and H5 which forms a series of arbitrary points from the scan path on the target, i.e. the beam path to produce on the target 1400 surface the ablation path as a queue of the spot areas.
  • the scan path can be continuous, according to an embodiment, from the scanner mirror part edge to the next edge (i.e.
  • the 1503Tr illustrates the beam part, which can go through the substrate in certain embodiments, for instance if the embodiments are used for a cut into the shape application and/or with partly transparent targets.
  • the component 1503Tr thus can be used for the estimating of even each individual pulse intensities and thus for the quality monitoring.
  • the 1503Tr can be neglibly small or a zero component at the drawn side.
  • that component may be replaced an available reflection at the same side as the incoming radiation.
  • the beam 1510 formed in the radiation source meets an expander 1508, which expands the beam to tapered shape, then the collimator unit 1507 to form a curtain-like broad but thin radiation wedge to be deflected by the turbine scanner 1502, through the correction optics 1501 optionally or in addition to polarization operation so that the beam 1503P hit the ablation target 1400 at the H1.
  • the correction optics can be thus used to define the spot area with its characteristic measure, as the diameter for instance, for the spot area on which the ablation threshold is exceeded, but of which the adjusting of the spot area to size in which the ablation threshold is slightly exceeded throughout the spot area with the provision of the pulse energy to being supplied.
  • Fig. 6 illustrates an arrangement 5700 according to an embodiment of the invention.
  • the example shown comprises a radiation source 5701 and/or another radiation source 5707.
  • the number of the sources as such is not limited only on one or two.
  • Fig. 6 also illustrates radiation path 5703 as arranged to guide radiation from a radiation source 5701 to the target 5706, to be used for ablating the target material from the spot area.
  • the path comprises a scanner 5704, but the number of scanners per path is not necessarily limited to the shown only.
  • the figure illustrates adapter 5702, 5705 arranged to adapt the path 5703 to the source 5701 and the target 5705, respectively.
  • the adapter can comprise an expander, contractor and/or correction optics parts, which are necessary for the focussing in such embodiments, in which the geometrical beam shape is necessary to change in the path from the source to the target for the desired spot area size.
  • Fig.6 also embodies such variations of the arrangement 5700 in which there is also an additional source 5707 to be used in parallel and/or in addition to the source 5701.
  • the additional source can be exactly the same according to one embodiment but according to another a different one.
  • the source is a heater arranged to heat the target.
  • the adapter 5708 can be the same as 5702, but is not necessary such. It can be also an integrated adapter as an expander.
  • the scanner 5709 can be same as the scanner 5704, but is not limited only thereto.
  • the scanner is a turbine scanner according to an embodiment of the invention. According to the way of drawing, the adapter 5710 is arranged so that the radiation from source 5707 arrives to the target 5706, as the radiation from the source 5701.
  • the arrangement do not necessary need the adapters at all, provided that the geometry of the beam directed via the scanner is sufficiently uniform and/or in correct focus to yield the spot area the necessary fluence to exceed the ablation threshold value; above, beneath or on the surface of the target material or its base.
  • the radiation of the radiation source can be in one embodiment directed to several targets, although only 5706 shown as an example.
  • Fig. 7 illustrates a prismatic low-faced turbine scanner 3321 , but especially the rotor part of it 3321.
  • the part 3321 can be a conventional turbine scanner part, but also a part according to an improved embodiment of the invention, provided with at least a coating of the mirrors with high durability for the high laser power pulses, as with diamond coating for instance.
  • the part 3321 has faces 3322, 3323, 3324, 3325, 3326, 3327 and 3328.
  • the arrow 3320 illustrates the rotation of the part 3321 around the axis 3103.
  • the faces are mirrors, each of which in-duty, arranged by its own turn, to deflect the incoming radiation beam via the radiation path and to cool when the mirror is off-duty.
  • Tilt angles of the faces are shown for various embodiments.
  • the Fig. 7 illustrates one revolution of the turbine scanner part in time scale from the first mirror, mirror 1 , to the last mirror, mirror 8.
  • An ablation path on the target can be thus demonstrated.
  • the ablation path is indicated to hit the target, which can be any target to be cold- worked, at the right by reference 3329, but in the left indicated with the same reference number the scanning path to be used to provide the ablation path.
  • the return of the beam is indicated by the line 3330.
  • the mirrors are indicated by the apparent reference number.
  • the location of the scan line on the target material may be the same in one embodiment for at least two successive scans, but the scan line for two successive scans can be different in another embodiment, if for example, the material is likely to form fragments even in cold-work based on ablation.
  • the number of faces is not limited to the 8, which is only an example in the figure. Faces can be of tens or even hundreds in number, however, influencing possibly to the scan line length.
  • the scanner mirrors can be also curved, although not shown in the Fig.7.
  • the corners can be rounded according to an embodiment of the invention.
  • number of different scan lines at the target surface can be achieved by variation of the tilt from face to the next face of the turbine scanner, or in another embodiment by changing the face tilt of at least one mirror or several mirrors.
  • the turbine scanner has an advantage that the beam won't stop one location at the target and thus the yield is rapid and homogenous during a scan resulting from a homogenous plume from the target.
  • the size of the turbine scanner is freely scalable for a skilled man in the art who has read the application text.
  • the embodiments comprise variations of microscopic scaled to macroscopic scale so that in the macroscopic scale according to one embodiment the diameter is about 12 cm and height 5 cm.
  • the distinction of low-faced turbine scanner from a high face turbine scanner can be made by the measures of the height of the mirror in an axial direction in relation to the width of the mirror in a perpendicular direction of the axial direction. If the height and width are essentially the same, or exactly the same such an intermediate embodiment is included to either low- or high- faced embodiment according to the ratio so that if the height is smaller than the width, it is low-faced but if the height is larger than the width it is high-faced.
  • turbine scanner in the radiation path for such systems in which use a pico-second laser systems whose repetition rate is above 4 MHz, advantageously over 20 MHz and/or the pulse energy is above 1 ,5 ⁇ J.
  • other type of scanners can be used with low repetition rates down to few 500 Hz form say 500 kHz.
  • FIG 8A illustrates an embodiment of the invention.
  • the measures are not necessarily in scale.
  • the spot area has a characteristic measure AB as a diameter, which much larger than the shallow ablation depth.
  • the pulsed laser source is indicated by the source, the beam being scanned with a mirror surface of the scanner to the round spot area with the diameter A-B.
  • An ablation threshold is marked as well as locations A and B on the surface of the target.
  • the yield (Y) and quality (Q) can be improved in comparison to same kind of scenario in Figure 8B with a smaller spot area with smaller diameter
  • the radiation source to be used in the arrangement according to an embodiment of the invention can comprise at least one or several diode-pumped radiation sources and each radiation source can have an optical path of its own, but not necessarily the same as another.
  • the radiation is laser radiation originating to radiation source arrangement according to an embodiment.
  • a radiation source arrangement according to an embodiment of the invention to be used for the pulsed radiation laser beam comprises a first feature and/or a second feature, which is at least one of the following:
  • said first feature is different than said second feature.
  • said feature is considered as an aspect of a radiation source.
  • the optical path is arranged to comprise at least one path for plurality of radiation sources comprising at least one radiation source arranged to direct at least one radiation beam to a plurality of targets comprising at least one target. If an embodiment is using intermittent pulsing for the cold working, the intermittency can be arranged in periodical way by using several sources each having own period, to be superposed at the hit point of the ablation path.
  • the laser source can be embodied, optionally or in addition, in suitable part according to the patent document FI20060182 incorporated herein by reference.
  • One further example embodies a laser arrangement according to an embodiment of the invention.
  • the mentioned parameter values are examples, and are thus not restrictive only to the mentioned values.
  • the turbine scanner as embodied is only an example, and thus not restrictive.
  • Pico-second laser system A
  • Scanner B
  • target feed C
  • the products can be of single crystalline diamond and/or silicon to be used as a substrate for semiconductor industry for instance, produced in vacuum, or in a gas atmosphere.
  • the coating can be formed on a surface of any kind, for example, on metal, plastics and/or paper to mention few. In one embodiment the coating has a coating layer thickness of 5 ⁇ m.
  • the semiconductor material can be silicon as pure or as a compound, but in a flexible form, suitable into use of electronics, micro and/or nano-electronics.
  • the points D, E, F and G help the manufacturing of high quality products in industrial scale, repeatable and promote the quality control.
  • Products that comprise surfaces and/or 3D materials having various functions can be produced in accordance with the invention.
  • Such surfaces include e.g. very hard and scratch-resistant surfaces and 3D materials in various glass and plastic products (lenses, monitor shields, windows in vehicles and buildings, glassware in laboratories and households); various metal products and their surfaces, such as shell structures for telecommunication devices, roofing sheets, decoration and construction panels, linings, and window frames; kitchen sinks, faucets, ovens, coins, jewels, tools and parts thereof; engines of automobiles and other vehicles and parts thereof, metal cladding in automobiles and other vehicles, and painted metal surfaces; objects with metal surfaces used in ships, boats and airplanes, aircraft turbines, and combustion engines; bearings; forks, knives, and spoons; scissors, hunting knives, rotary blades, saws, and all types of cutters with metal surfaces, screws, and nuts; metallic processing means used in chemical industry processes, such as reactors, pumps, distilling columns, containers, and frame structures having metal surfaces; piping for oil, gas, and chemicals; parts
  • Yet other products fabricated in accordance with the invention may include surfaces and 3D materials resistant to corrosive chemical compounds, semiconductor materials, LED materials, pigment materials and surfaces made thereof which change color according to the viewing angle, parts of laser equipment and diode pumps, such as beam expanders and the light bar in the diode pump, jewel materials, surfaces of medical products and medical products in 3D shapes, self-cleaning surfaces, various products for the construction industry such as pollution- and/or moisture-resistant and, if necessary, self-cleaning stone and ceramic materials (coated stone products and products onto which a stone surface has been deposited), dyed stone products, e.g. marble dyed green in accordance with an embodiment of the invention or self-cleaning sandstone.
  • surfaces and 3D materials resistant to corrosive chemical compounds, semiconductor materials, LED materials, pigment materials and surfaces made thereof which change color according to the viewing angle parts of laser equipment and diode pumps, such as beam expanders and the light bar in the diode pump, jewel materials, surfaces of medical products and medical products in 3D shapes, self
  • the invention shows a method of producing high-quality ablation plume by processing a target, on a target body, with a pulsed laser beam radiation, so that the method comprises: selecting a spot area for a beam cross-section on the target to correspond the ablation threshold of the target material to being exceeded throughout the spot area of which the plume is ablated by the pulsed beam radiation within a controlled ablation depth so providing the fine quality plasma, to be used for coating and/or particle synthesis.

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Abstract

The invention shows a method of producing high-quality ablation plume by processing a target, on a target body, with a pulsed laser beam radiation, so that the method comprises: selecting a spot area for a beam cross-section on the target to correspond the ablation threshold of the target material to being exceeded throughout the spot area of which the plume is ablated by the pulsed beam radiation within a controlled ablation depth so providing the fine quality plasma, to be used for coating and/or particle synthesis.

Description

Surface processing method
Field of invention
The invention relates to ablation techniques in very general level, but more specifically to a method of making high quality plume. The invention relates also to surface processing by ablation for achieving by ablation a smooth surface feature for the surface to be processed. The invention relates also to use of the plume in a coating method. The invention relates also to a method of making particles.
Background
Traditional known methods of the PLD-techniques as well as the related problems can be identified from a various patent publications. The major disadvantages of low repetition rate, powerful nanosecond-range laser pulses as being used to evaporate the target as well as the reported intention of particle formation as fragments and droplets are identified. As a consequence, when coating, the substrate surfaces may catch and comprise the fragments. An improved methods are sought to provide for deposition of thin amorphous and structural films including the steps of sequentially evaporating small amounts of material to be deposited from a target of the material with each pulse of a laser irradiating the target, each pulse having an energy less than that required to evaporate sufficient of the material to result in a significant number of particles in the evaporated plume and depositing the evaporated material on a substrate to form a film. The traditional methods of PLD-techniques are related to the repetition rates about tens of Hz, although also pico-second and femto-second laser pulses are known to be used at the repetition rates from few kHz- to hundreds of MHz as such, with very low pulse energy. According to 6,312,768 the particle production of the conventional PLD -methods are estimated via the released number of atoms to be in level of 1 O19"20 # per pulse so being sufficient to yield 108 # micron sized particles. Although the above mentioned patent publication maintains a drastic decrease in the particle number of micron sized particles down to 1 micron sized particle from the 1011 atoms per pulse, such particles are far to large for a proper smooth surfaces on the substrates when coated. The techniques used in PLD-in a conventional like manner also has the disadvantage, that even if the laser used for the ablation were an ps-laser, the repetition rates may be limited only to several tens of kHz, so influencing to the yield of the coating, if the problems of the quality of the plasma are not considered, or the unpredictability of the particle's size and the shape of the fragments.
Summary
However, in the conventional PLD-techniques, the yield from the target into the plume is important to the various applications, in which the substrate is to be carved with a pattern and cut, but even more important to the applications in which the substrate is desired to be coated, with a particle free coating, optionally with a structure with certain sized particles on the surface, or when it is the particles that are being in the interest. Also particle synthesis in controlled conditions requires particle free conditions to start with. These are problematic situations to the conventional PLD-techniques when met, if not entirely impossible, in a reasonable time and quality.
It is an object of the invention to provide a new method of producing high-quality ablation plume. The method can be thus used in processing a target surface so that the processing leaves a smooth surface to the target surface that is being processed in a carving like action and/or cut according to the first aspect of the invention, with minimum particles or left-over fragments. It is also a related object of the invention to use the plume for providing a smooth coating on the substrate surface to be coated, according to a second aspect of the invention. According to a third aspect of the invention, the first and second aspects of the invention can be applied in combination to surfaces that are processed in various combinations with carving, cutting and/or coating. According to a fourth aspect of the invention the plume can be made and used for controlled inorganic nano-particle formation via nucleation phenomena and/or condensation followed.
Let the reader being noted that certain liquid like, metal-like and/or ceramic-like carbon compounds as well as other carbon containing substances and/or compositions that contain carbon as one of the main constituents are counted to inorganic. According to the origin of compounds or compositions to a living organism or a normal constituents thereof containing carbon in combination to hydrogen, oxygen, sulphur and/or nitrogen as main constituents can be counted to organic as well as the debris of organisms can be counted to organic matter. Thus, for instance cells as such as well as dna and hydrocarbons as well as the normally organic counted compositions are counted organic. If a carbon compound were to be counted to both, the correct category should be judged by the importance in its form to the life. The problems of the conventional techniques are solved, if not entirely for all nuances of the known problems, at least mitigated by the methods according to the invention.
Embodiments of the invention are based on the notice, that especially in cold ablation, the yield to the plume as well as its quality can be kept very high, i.e. free of fragments in certain large particles sizes, for instance, above 1000 nm when, the energy of the beam pulse is distributed onto such a spot area on the target surface on which the pulse energy part at each point of the spot area is sufficient to slightly exceed the ablation threshold of the target material. The ablation depth is controlled to be shallow and the plume formed from the spot area on which the ablation threshold is exceeded.
By such a selection of the pulse energy to correspond the spot area in this way, one can avoid to energize the ablation spot more than necessary for the ablation plume formation, but increase the yield by increasing the spot area size, which is contrary to the teachings of conventional techniques according to which the decrease of spot size would yield an increase to the ablation rate. As a consequence the energy versus maximum area above ablation threshold at the spot area also yields the advantage that the ablation depth, from which the plume originates at the spot area, is very shallow, and thus fragment formation in the scale of conventional PLD -scale is avoided. In other words, according to an embodiment of the invention the spot area can be defined as the largest continuous spot area on the target, of which area comprises of the points at which the ablation threshold is exceeded as little as possible to maintain ablation throughout the spot area.
A method of producing high-quality ablation plume according to the invention is characterized in the characterizing part of an independent method claim thereof. A coating method according to the invention is characterized in the characterizing part of such an independent method claim thereof. A controlled particle making method according to the invention is characterized in the characterizing part of such an independent method claim thereof. Examples on other embodiments of the invention are shown in the dependent claims. Various embodiments of the invention are combinable in suitable part.
According to an embodiment of the invention a method of producing high-quality ablation plume by processing a target, on a target body, with a pulsed laser beam radiation is comprising: selecting a spot area for a beam cross-section on the target to correspond the ablation threshold of the target material to being essentially exceeded throughout the spot area of which the plume is ablated by the pulsed beam radiation.
According to an embodiment of the invention, if the radiation source is know to be able to deliver certain energy for a fluence to exceed the ablation threshold of the target material, the size of the spot area can be selected accordingly to match as based on the exceeding criteria through out the area for the energy in each point of the spot area. According to an embodiment of the invention the spot as ablation spot is made to roam on the target surface, on an ablation path, which can be pre- determined by the respective movements of the scanner surface and the target to make the spot roam on the target body.
According to an embodiment of the invention the method also comprises selecting pulse energy, for a pulse of a pulsed laser beam radiation, to be distributed on to a spot location at the target, and to exceed an ablation threshold fluence of the target material throughout the spot area.
According to an embodiment of the invention the method also comprises defining the spot area via the energy to meet the ablation threshold of the target material by terms of fluence to be essentially exceeded throughout the spot area.
According to an embodiment of the invention the method also comprises setting an optical path for directing said laser beam radiation to meet said spot area with said fluence.
According to an embodiment of the invention the method also comprises scanning said pulsed laser beam radiation on the target surface for defining a location of the spot with said spot area to be ablated from the target surface.
According to an embodiment of the invention the method also comprises ablating at the location of said spot, the material from the spot defined by said scanning, to an ablation depth with said pulsed laser beam into a plume.
According to an embodiment of the invention, the spot size is kept as large as possible to meet the ablating-enabling fluence inside the spot area region, slightly to exceed the ablation threshold. The repetition rate can be in kHz range, advantageously in few hundreds of kHz to few MHz. Thus, the yield to plume can be kept as large as possible, from the interior parts of the spot area, but also more uniform and particle free. When the size of the spot area is so maximized, the surrounding region in which the pulse energy is not anymore slightly exceeding the ablating threshold, but instead equates, essentially equates or is just below the ablating threshold, can be so kept relatively low in respect to the spot area. Thus also the contribution of the surrounding region with the potential variations of quality can be kept low to the whole plume as whole. Also the variations of the plume constituent velocities are expected to be smaller and thus the plume more uniform and predictable than in cases where the pulse energy is much higher on a small spot than the corresponding ablation threshold. According to an embodiment of the invention the spot is formed by an out-of-focus-beam-cone.
According to an embodiment of the invention the smooth surface feature in the method is at least one of the following: a smooth carving path, a smooth cut line, a smooth pattern on the surface.
According to an embodiment of the invention the scanning in the method is implemented in the method by a turbine scanner at least partly, i.e. the optical path comprises a scanner surface that is of a turbine scanner. So, the scanning speed can be very rapid and high repetition rates are gained within large purity and fine smoothness of the surface.
According to an embodiment of the invention the scanning in the method can be implemented at least partly by a vibrating and/or mirror scanner. These embodiments are suitable in various applications, where the plume quality is not as critical as in those applications that are implemented to use turbine scanner and/or the yield is not so critically kept high.
According to an embodiment of the invention the area of the spot size is defined in the method by a characteristic measure which is at least one of the following: ablation depth, a diameter of the spot area, a perimeter of the spot defined along a closed equal-energy-line of a spot, the volume of the material to be ablated and ablation depth.
According to an embodiment of the invention the spot area is set to its characteristic size at the target for pulse energy that is larger than 0,5 μJ for an individual pulse arriving to the target. Optionally or in addition, according to an embodiment of the invention the spot area is set to its characteristic size for pulse energy that is larger than 5 μJ for an individual pulse. Optionally or in addition, according to an embodiment of the invention the spot area is set to its characteristic size for pulse energy that is larger than 10 μJ for an individual pulse. Optionally or in addition, according to an embodiment of the invention the spot area is set to its characteristic size for pulse energy that is larger than 50 μJ for an individual pulse. Optionally or in addition, according to an embodiment of the invention the spot area is set to its characteristic size for pulse energy that is larger than 100 μJ for an individual pulse. Optionally or in addition, according to an embodiment of the invention the spot area is set to its characteristic size for pulse energy that is larger than 200 μJ for an individual pulse. Optionally or in addition, according to an embodiment of the invention the spot area is set to its characteristic size for pulse energy that is larger than 500 μJ for an individual pulse. Optionally or in addition, according to an embodiment of the invention the spot area is set to its characteristic size for pulse energy that is less than 5000 μJ for an individual pulse. Optionally or in addition, according to an embodiment of the invention the spot area is set to its characteristic size for pulse energy that is less than 50 000 μJ for an individual pulse. Optionally or in addition, according to an embodiment of the invention the spot area is set to its characteristic size for pulse energy that is less than 500 000 μJ for an individual pulse. Optionally or in addition, according to an embodiment of the invention the spot area is set to its characteristic size for pulse energy that is less than 15 J for an individual pulse. The pulse energy is spread over the spot to keep just above the ablation threshold. The distributing of the energy can be made by the optics in the optical path leading from the radiation source to the target via scanner. According to an embodiment, the heating of the target by an electrical heater or a beam can influence on the energy needed to exceed the ablation threshold.
According to an embodiment of the invention, the repetition rate of the pulses is larger than 20 kHz. Optionally or in addition, according to an embodiment of the invention the repetition rate of the pulses is larger than 200 kHz. Optionally or in addition, according to an embodiment of the invention the repetition rate of the pulses is larger than 2 MHz. Optionally or in addition, according to an embodiment of the invention the repetition rate of the pulses is less than 10 MHz.
However, if very large spot areas available, the repetition rate can be even lower down to kHz range or even lower, within the provision that the plume-yield from the spot area is comparable to that from a higher pulse rates, say, in MHz range for instance in cold ablation with a cold ablation laser.
According to an embodiment of the invention the ablation depth is smaller than 500 nm, for an individual pulse arriving to the target. Optionally or in addition, according to an embodiment of the invention the ablation depth is smaller than 50 nm, for an individual pulse arriving to the target. Optionally or in addition, according to an embodiment of the invention the ablation depth is smaller than 5 nm, for an individual pulse arriving to the target. Optionally or in addition, according to an embodiment of the invention the ablation depth is smaller than 1 nm, for an individual pulse arriving to the target. Optionally or in addition, according to an embodiment of the invention the ablation depth is smaller than 0, nm, for an individual pulse arriving to the target. Optionally or in addition, according to an embodiment of the invention the ablation depth is larger than 0,01 nm, for an individual pulse arriving to the target. Optionally or in addition, according to an embodiment of the invention the ablation depth is larger than 1 nm, for an individual pulse arriving to the target. Optionally or in addition, according to an embodiment of the invention the ablation depth is larger than 10 nm, for an individual pulse arriving to the target. Optionally or in addition, according to an embodiment of the invention the ablation depth is larger than 100 nm, for an individual pulse arriving to the target.
According to an embodiment of the invention the method of producing high-quality ablation plume can be used in a method of surface processing to make by ablation a smooth surface feature for the surface to be processed as a target on a target body, according to an embodiment of the invention.
According of an embodiment of the invention the spot is defined by the beam cross-section being out of the focus on the target surface. According to an embodiment of the invention spot is formed on to the target that has a smaller ablation threshold as the scanner surface so facilitating a diverging, a conical-like geometry for the beam and the corresponding cross-section for the spot.
According to an embodiment of the invention the medium has a phase of at least of the following:
- a gas that has a state from at least one of the following:
--in high pressure,
--in normal pressure,
--in under pressure and
--in practical vacuum, 06 Mar 2009 8
- a liquid, and
- a multiphase medium comprising liquid phase and a gas phase with gas that has a state.
A coating method according to an embodiment of the invention is implemented so that the substrate to be coated in the method with a smooth coating comprises a method of surface processing according to an embodiment of the invention for achieving fine plume to be used for the smooth coating of the substrate.
According to an embodiment of the invention, the spot at the target can be further defined by the adhesion with the substrate in a coating method according to an embodiment of the invention. So a better quality surfaces can be optimized for the coating - substrate pair for the particular use.
According to an embodiment of the invention, the spot at the target can be further defined by the optimization criteria of particlelessness of the plume. The plume can be optimized for the conditions that avoid particle formation.
According to an embodiment of the invention the amount of the matter that can nucleate from its phase in the plume to a liquid or solid phase and so to form particles in the medium can be controlled by keeping the nucleation rate very low via the ablated material concentration in the plume, to correspond the conditions of constant temperature at the near saturation conditions.
There are different types of nucleation phenomena to occur and the known mechanisms are available as such in the temperature and pressure derivable conditions. Thus, the amount of the material in the plume generated by the method according to an embodiment of the invention, the concentration of plume material that corresponds the vapour pressure of the plume material, is thus kept lower than the saturation vapour pressure corresponding matter in the plume conditions and thus the nucleation is not initiated in significant scale, practically not at all. Thus, for instance, the method can be embodied for particle making applications within an expansion chamber. Expansion chamber is well known as such. The medium that contains the vapours to form particles, is allowed to cool proportionally to the volume change in the chamber, so causing the temperature of the medium to decrease, but however, simultaneously as the partial vapour pressures are proportional to the temperature via an exponential function, very high saturation ratios can be gained. According to an embodiment of the invention the coating method according to an embodiment of the invention yield a coated substrate surface that comprises less than a pinhole per 1 mm2, preferably less than one pinhole per 1 cm2, even more preferably a pinhole per 1 km2, but most preferably no pinholes at the surface on the substrate body to be coated.
According to an embodiment of the invention the coating method according to an embodiment of the invention yield a coated substrate surface is coated in such a manner wherein the first 50 % of the product surface layer does not contain any particles having a diameter exceeding 1000 nm, preferably 100 nm and most preferably 30 nm.
According to an embodiment of the invention the coating method according to an embodiment of the invention yield a coated substrate surface, wherein the average surface roughness of produced articulating surface layer is less than 100 nm as scanned from an area of 1 μm2 with an Atomic Force Microscope (AFM).
However, as such a pre-nucleation threshold conditions of the vapour pressure of the material in the plume is exceeded, on purpose by controlling the amount of the matter in the plume and/or cooling the plume, particles can be made according to an embodiment of the invention in controlled conditions. According to an embodiment of the invention the method according to an embodiment of the invention can be used to form the plume, and the plume is so cooled in a cooling phase for cooling the plume in the medium for producing particles via a nucleation phenomena. According to an embodiment of the invention the nucleation phenomena in the method comprises at least one of the following:
- ion induced nucleation within the medium having charged material present to use the ions as the seed-nuclei,
- homogeneous nucleation,
- heterogeneous nucleation within the medium having presence of nucleation seeds for the nucleation to occur on a surface.
According to an embodiment of the invention, the nucleated particles are grown by condensation of the material originating to the plume. According to an embodiment of the invention, more plasma is inputted to the plume to replace the nucleated and/or condensed material so to maintaining said nucleation and/or condensation. According to an embodiment of the invention, after the reach of a pre-determined particle size, the plume is diluted for preventing aggregate formation, and/or the particle coalescence. The particles are collected from the medium. According to an embodiment of the invention, the plume comprises of at least one of the following inorganic constituents of the plume: ions, plasma constituents, atoms, molecules, nano-particles smaller than 10 nm in size, nano-particles smaller than 40 nm in size, matter that has characteristic size in an intermediate range of the afore mentioned size.
According to an optional embodiment of the invention, the plume instead of plasma of inorganic alone can comprise organic matter in form of organic cells and/or their constituents to be ablated according to the first, second and/or third aspect of the invention.
According to an embodiment of the invention the medium that is in contact with the target material can be liquid. According to an embodiment of the invention the liquid is arranged to receive the plume. According to an embodiment of the invention the plume can occur in a liquid and consequently the rapid cooling of the plume constituents can form particles into the liquid and further removed from the liquid. Arranging the liquid input for pure liquid and output with the particles into the balance, a continuous process can be maintained as far as the target material is available. Such an immersion related ablation may be interesting option also for removing cells from an organic target, into the liquid and arranging the liquid for further use with the cells.
According to an embodiment of the invention the material in the plume comprises of inorganic constituents for forming a ceramic coating or ceramic-like coating.
According to an embodiment of the invention the radiation source to be used within the method is a hot ablation laser source. According to an embodiment of the invention such a laser source comprises at least one nanosecond laser.
According to an embodiment of the invention the radiation source is a cold ablation laser source. According to an embodiment of the invention the laser source comprises at least one of the following: a pico-second laser, a femto-second laser and an atto-second laser.
According to an embodiment of the invention the material in the plume comprises of organic cells and/or their constituents. The effective depth of the heat pulse from a laser pulse hitting the surface of a material varies considerably between laser systems. This affected area is called the heat affected zone (HAZ). The HAZ is substantially determined by the power and duration of the laser pulse. For example, a nanosecond pulse laser system typically produces pulse powers of about 5 MJ or more, whereas a pico-second laser system produces pulse powers of 1 to 10 μJ. If the repetition frequency is the same, it is obvious that the HAZ of the pulse produced by the nanosecond laser system, with a power of over 1000 times higher, is significantly deeper than that of the pico-second pulse. Furthermore, a significantly thinner ablated layer has a direct effect on the size of particles potentially coming loose from the surface, which is an advantage in so-called cold ablation methods. Nano-sized particles usually will not cause major deposition damages, mainly holes when they hit the substrate. In an embodiment of the invention, fragments in the solid (also liquid, if present) phase are picked out by means of an electric field. This can be achieved using a collecting electric field and, on the other hand, keeping the target electrically charged so that fragments moving with a lower electrical mobility then the plume constituents can be directed away from the plume.
An aim of the invention is to introduce a method for coating the target to be coated more efficiently and with a higher-quality surface than what is known in the prior art at the priority date of the present application. The aims of the invention are connected to the following objects enlisted below as follows:
It is a first object of the invention to achieve at least a novel method and/or means connected thereto for solving the problem how to produce fine, high-quality plume in practice of whichever target, so that the target material does not form any fragments at all into the plasma, i.e. the plume is pure, or said fragments, in case they exist, occur only scarcely and are smaller in size than the ablation depth, from where said plume is produced by ablating said target.
A second object of the invention is to achieve at least a novel method and/or connected means for solving the problem how, by releasing high-quality plasma, there can be produced a fine and uniform cutting line to be utilized in a cold work method that removes material from a target as far as the ablation depth, so that the target to be worked does not form any fragments that could be mixed in the plasma, in other words the is pure, or said fragments, in case they exist, occur only scarcely and are smaller in size than said ablation depth, from where said plume is produced by ablating said target. A third object of the invention is to achieve at least a novel method and/or connected means for solving the problem how to coat the surface of an area serving as a substrate by using high-quality plume that does not contain any particle-like fragments at all, in other words when the plume is pure, or when said fragments, in case they exist, occur only scarcely and are then smaller in size than said ablation depth from where said plume is produced by ablating said target, in other words how to coat the substrate surface by using pure plume that can be produced practically from any material.
A fourth object of the invention is to achieve at least a novel method and/or connected means for solving the problem how to create by means of high-quality plume a coating with good adhesion features for gripping the substrate, so that the wasting of kinetic energy in the particle-like fragments is reduced by restricting the occurrence of the fragments or by restricting their size to be smaller than the ablation depth. At the same time, owing to their absence, the fragments do not create cool surfaces that could affect the homogeneity of the plume jet through the phenomena of nucleation and condensation. Moreover, according to the fourth object, the radiation energy is effectively transformed to plume energy, as the area affected by heating is minimized when using advantageously short radiation pulses, in other words pulses of the pico-second order or even shorter duration, and in between the pulses, there is applied a certain interval in between two successive pulses.
A fifth object of the invention is to achieve at least a novel method and/or connected means for solving the problem how to achieve a wide scanning width simultaneously with the quality of high-quality plume and a wide coating width for even large objects on an industrial scale.
A sixth object of the invention is to achieve at least a novel method and/or connected means for solving the problem how to achieve a high repetition frequency to be used in industrial-scale applications, in line with the above enlisted objects.
A seventh object of the invention is to achieve at least a novel method and/or connected means for solving the problem how to produce high-quality plume for coating surfaces and manufacturing products in line with the objects from first to sixth, but still save target material to be used in the coating steps for generating re- coatings/thin films of the same quality, where it is needed. It is yet another extra object of the invention to apply such methods and means in line with said first, second, third, fourth and/or fifth objects, for solving the problem as how to cold work and/or coat surfaces, in an appropriate line with respect to each suitable type of such products.
Other embodiments of the invention are indicated in the dependent claims and in the following part of the description, by a reference to be made to give examples on the embodiments of the invention in a non-restrictive manner, so not only to restrict the scope to the indicated examples of the embodiments, but instead helping to understand advantages of the embodiments of the invention.
Various embodiments of the invention are combinable in suitable part. The term "comprise" has been used as an open expression. Term "one embodiment" as well as "another embodiment" has been used for simplicity reasons to refer to at least one embodiment, but can also comprise an ensemble of embodiments with the indicated feature, alone, or in combination of suitable other embodiments. When read and understood the invention, the skilled men in the art may know many ways to modify the shown embodiments of the invention, however, without leaving the scope of the invention, which is not limited only to the shown embodiments which are shown as examples of the embodiments of the invention.
Figures
In the following, examples on embodiments of the invention are given in an illustrative manner without any intention to limit any embodiments of the invention to the merely shown material. Number values are illustrative examples in non- restrictive spirit.
Fig 1 illustrates a particle producing according to an embodiment of the invention, in accordance to the plume producing method,
Fig 2 illustrates a plume producing method according to an embodiment of the invention for producing high-quality ablation plume, and a coating method that utilises said method,
Fig 3 illustrates an embodiment related to carving and grooving embodiment and/or coating method,
Fig 4. illustrates an embodiment for making several coatings, Fig 5 illustrates scanning a beam onto a target according to an embodiment of the invention,
Fig 6 illustrates utilisation of several sources for the pulsed radiation to be used in ablation plume formation,
Fig 7. illustrates an example of scanning the spot area having a size of 40 μm and a scan line,
Fig 8A and 8B illustrate advantages of an example according to an embodiment of the invention for the plume yield and quality.
Ensemble of embodiments of the invention
According to an embodiment of the invention a suitable pulse length for a target material is less than 30 ps to be counted as a short pulse. However, even shorter pulses can be used down to the 1 ps scale in one embodiment, but pulses within the fs-scale duration in another embodiment or even as-scale (atto-second-) in a further embodiment can be used down to 0,05 as (atto-second).
According to an embodiment of the invention, the pitch between two successive pulses is equal or shorter than the pulse duration, but kept constant. According to an embodiment of the invention the pitch duration is longer than the pulse duration but kept constant. Constant pitch and/or pulse length makes the radiation source simpler and easier to manufacture as a laser source. But according to an embodiment of the invention, a pumped laser source can be arranged to have at least some intermittency for the pitch and/or the pulse duration achievable in the energization by using a plurality of pumping mechanisms timed intermittently or differently timed to yield intermittence and to make the pumping either optically and/or electrically embodied in suitable part. Such an intermittent radiation can be used, for instance, if different material/structure of the ablation path is to be desired to the target. The intermittently pulsed laser can be a pumping laser to be used to pump a power laser according to an embodiment, or the intermittently pulsed laser can be itself a power laser, that is pumped by several mechanisms.
According to a cold work method according to an embodiment of the invention, the pulse characteristics of the radiation to be used for the ablation can comprise such features as the pulse power, pulse energy, pulse shape, pulse duration, pitch between two successive pulses, intermittence, pulse/pitch repetition rate of the pulses on the target, repetition rate of the pulses on the scanner, cover ratio of the pulses on the target and/or a combination thereof. The cover ratio of the pulses can be defined by a ratio of the common area of two successive hit spots to the area of an arbitrary hit spot.
According to a cold work method according to an embodiment of the invention, characteristic wavelength means a wavelength that originates to the laser source that is used for the ablating. The laser source can have several polarization modes at the characteristic wavelength, from which a certain mode can be selected to be used in the ablation in one embodiment, but in another embodiment several modes and/or characteristic wavelengths can be used when associated to the suitable pulse characteristic or characteristics. According to an embodiment of the invention the radiation to be used is in the wavelength range from radio wavelengths down to ultraviolet wavelengths or even down to low energy x-ray wavelengths. According to an advantageous embodiment of the invention the wavelength of the radiation comprises monochromatic and coherent radiation component that has a wavelength of radio waves IR, UV, visible light. Also intermediate ranges can be applied in embodiments.
According to a cold work method according to an embodiment of the invention, that uses the method of producing high-quality ablation plume, ablation path can be predefined, so as to be used for defining the order in which the material from the ablation target is to be ablated. According to an embodiment of the invention the ablation path can comprises a spot or to be a spot-like, for applications in which a dot "." is to be formed on the ablation target. The dot can be gap, cavity or an ablation-drilled hole, even through the ablation target piece from its one side to another, said dot having a shape derivable from the ablating radiation geometry. According to an embodiment of the invention the path comprises a line, which is thus a queue of the hit spots of the spot area on the target surface.
Provided that the hit spots, the spot areas, are essentially or completely non- overlapping, the hit spots form a line along the surface on the ablation target surface, according to the radiation geometry of the pulsed laser beam to form the dots, is referred as a carving embodiment. According to an embodiment directed to the drilling, in such embodiment of the invention, the hit spots are essentially at the same location for making a hole and/or cavity along the normal of the surface. However, also holes that define a direction with such an angle that is between a surface and its normal can be drilled according to an embodiment of the invention. In such a case non-normal-direction drilling, the overlapping of the hit spots are arranged to define the direction of the cavity. According to an embodiment of the invention, the drilling may be made at least some part so that part of the radiation of the pulse goes through the plume. According to an embodiment of the invention the plume can be further ablated by another beam arranged to remove the plasma, or the ablated plume can be removed at least partly by electromagnetic means arranged to provide an electromagnetic field to interact with the charged plume particles in order to deflect the plume away from the incoming radiation pulses. According to an embodiment of the invention the ablation-originating plume is kept small so to be easily and quickly dismissed. According to an embodiment of the invention the pulse rate is adjusted to match to the intermittence of the drilling action time scale of proceeding drilling according to the time in which the plume is dismissed from the existing hole, i.e. the pitch between the pulse is getting longer during the proceeding drilling.
According to an embodiment of the invention, the pulse shape is chosen so that the laser pulse has a first pulse-part that has a first power level capable of ablating target material at the hit spot, and a second pulse-part that has a second power level, which is higher than said first power level so capable to compensate extinction of the plume. Such a pulse can be advantageous in certain embodiments in which the carving and/or drilling should be made through the plume directed radiation pulses.
According to an embodiment of the invention the ablation target can be in rest in respect to the laser source. According to an embodiment of the invention, the ablation path on the ablating target is defined by a respective movement of the laser source and the target body. According to an embodiment of the invention, the target is hold by a holder that is arranged to move the ablation target body so that its surface comprises at least partly the ablation path having the characteristic dimensions of the ablation path and the appropriate ablation depth in each defined location of the ablation path, as defined according to radiation geometry of the laser source. According to an embodiment a scanner is used to scan the target surface i.e. to allow the spot roam along a pre-determined path on the target.
According to an embodiment of the invention the ablation target can be arranged to rotate so having the ablation path along the surface of said target. If the rotational movement is suitably constant and occurs around a fixed axis, an embodiment of the invention can be used for cutting the ablating target, as in turning machines and/or reamers. Also other carving-like actions can be arranged to occur in a similar way as in a turning machines and/or reamers. For example, according to an embodiment of the invention, the target piece can be placed on to a robot providing movements in an xy-plane, z-plane and/or at least one rotating movement so providing at least in theory access of the ablating beam to any visible surface location, for a carving action and/or cutting parts of the ablation target body.
According to an embodiment of the invention the carving can be made in a low pressure that is however higher pressure than the pressure in outer interstellar free space, but lower than an atmospheric pressure. According to an embodiment of the invention the carving can be made in over pressure condition, and/or in a specific gas atmosphere for yielding protection against the diffusing plume materials to the parts that may be critical for the material.
According to an embodiment of the invention the laser radiation geometry can be a beam, as approximated as a one-dimensional line from the source to scanning optics and further to the ablation target, so advantageous to be utilised in formation of ablation paths that have a breadth in order of ten or several tens of times or smaller breadth. According to another embodiment of the invention, the laser radiation geometry can be as a fan of beams, as approximated as a two- dimensional plane from the source to scanning optics and further to the ablation target on which the fan causes a surface oriented line by one pulse shot, so defining an area to be carved on to the ablation target by several adjacent pulses.
According to an embodiment of the invention the radiation geometry can be approximated as a cone that converges towards the target surface. According to an embodiment of the invention, the spot area is formed by a cross section of the cone. According to a variant of the embodiment, in which the scanner surface comprises higher ablation threshold as the target, the cone from the scanner to target can be arranged diverging towards the target. This can be achieved for instance by the curvature of the scanner mirror surface to match to the desired geometry.
According to an embodiment of the invention several fans of beams can be arranged to hit the ablation target simultaneously so defining an area by one pulse shot, provided that the power is sufficiently large to cause ablation at said area to the appropriate ablation depth of one pulse shot. This can be also provided by a bunch of optical fibres and/or beam expanders with sufficient tolerance to tolerate high energy level of the laser. According to an embodiment the examples that were shown to enlighten the embodiments of the invention that has been concentrated to the manufacturing or creating something that has to be cut or carved.
According to an embodiment, the ablation target is kept in rest and the ablating radiation is directed via an optical path to the ablation target that is held still.
According to an embodiment both the ablation target and the ablating radiation are to be moved in respect in each other, but also in respect to a virtual third party observer.
However, the method has also embodiments that are directed to destruction of enemy and/or the military material of such. According to an embodiment of the invention, when the working method embodied applicable as to weapons, also long pulsed lasers can be used having the pulse duration over 80 ps, even up to micro second scale. The fragments may be not the problem of the weapon user, and thus also the thermal transfer does not have a role to play, does a destroyed enemy, its material, vehicle and/or tank have smooth cut line or not. According to an embodiment of the invention, the larger spot size can be used for more destruction.
According to an embodiment of the invention cold-work lasers can be used also in disarmament of explosives, so cutting by ablation the detonating path from the ignition primer to the essential explosive material away, or by ablating critical parts of a bomb so to disarming it. Optionally or in addition, the explosive material is cut to smaller pieces to be removed so that if the ignition occurs, only the primer and/or a small amount of the explosive goes off. That is possible because the material structure of the explosive is not sufficient enough capable to relay the thermal transmission from the hit spot to the surrounding material. Also, the detonation speed can be in order of 10 km/s, may be much lower in reality, which shown estimate speed is quite slow in comparison to the actions that happen in the material between its structural parts.
According to an embodiment of the invention the cold-work by ablation can be used in purification of materials, provided that the plume is to be handled as such, so as at least some of the constituents to be separated in suitable part from the other. According to an embodiment of the invention the material that is ablated from the ablating path is arranged to originate from such a target that has a material layer arranged to be used in coating by ablation, by placing and/or moving the body to be coated into the plume.
According to an embodiment of the invention the ablating radiation is directed from the source to the working spot at the ablation target via an optical path, which can be embodied in one embodiment by a fibre based path in suitable part, but in another embodiment in suitable part in vacuum. According to an embodiment of the invention the path comprises a scanner arranged to scan the radiation to the working spot area on the ablation target. According to a preferred embodiment of the invention, the scanner is a turbine scanner, which has a rotatable structure arranged so that it comprises a first mirror surface part that is arranged to direct said radiation towards the working spot while another, a second mirror surface part of a previous location of the radiation spot on a mirror surface of the scanner is arranged to cool.
According to an embodiment of the invention a scanner to be used is a known scanner as such.
According to an embodiment of the invention, also geometry of the beam can be adjusted by a suitable beam expander where necessary to apply the scanned beam to a certain geometry to enlarge the hit spot to the spot area, provided that sufficient power for the ablation at the area is available to meet the ablation threshold throughout the spot area.
According to an embodiment of the invention a prismatic-like but longer than a disk turbine scanner, in direction of the rotation axis length, can be used for radiation geometries that are arranged to provide a line oriented hit spot.
According to an embodiment of the invention the mirrors comprise a curved surface part so arranged to deflect the ablation path at the ablation target in a certain repeatable way. According to an embodiment of the invention the curvature can be, as arranged in the plane of the scanner movement linear or rotation in respective embodiments, positive but according to another embodiment negative, as respectively defined by the distance of the nearest part of the mirror to the movement / rotation axis as being in minimum with the positive curvature and as maximum with the negative curvature. According to an embodiment of the invention the curvature can be arranged in the plane of the movement/rotation axis, i.e. in perpendicular to the movement/rotation defined plane. According to an embodiment of the invention also multiple curvatures can be used in order to arrange a repeatable ablation path on the ablation target.
According to an embodiment of the invention, the scanner to be used comprises parts made of nano-tube material because of the tolerance against the forces in the movement. The scanning surfaces of the scanner can be coated with carbo- nitride (CsN4) for improved mechanical and/or thermal durability to tolerate high- energy pulses of the laser source.
In the following, a working method according to an embodiment of the invention is described as an example in a non-restrictive manner as such.
According to an embodiment of the invention, ablation to be used in the cold work is made by a laser source radiating laser-radiation that has at least one characteristic wavelength. In an embodiment, single cavity can provide also harmonic waves with a different wavelength, but such may be not directly utilizable as such to the ablation according to an embodiment of the invention.
According to an embodiment of the invention the laser source is selected for the cold-work so that its radiation is pulsed so that the pulses have duration that is shorter than 50 ns (nanoseconds), but according to an embodiment advantageous for a probability to cause less fragmentation of the ablation target at the spot area, has the pulse duration is shorter than 50 ps (picoseconds), but according a further advantageously for a probability to cause less fragmentation, shorter than 10 ps pulse duration. According to an embodiment of the invention the pulse length can be even shorter, as in one embodiment in the fs-range (femto-second) arranged to be used for the ablation along the ablation path. According to an embodiment of the invention, a hot work ns-laser is used, but the scanning of a pulse is made so that the target experiences a cold-work ablation during the pulse because of the movement of the spot area on the target in motion.
Figure 1 illustrates an embodiment as a particle making method according to the invention. The method related phases for the preparation and some details are omitted for clarity reasons. In the phase 101 a plume is made, formed from the target material according to an embodiment of the invention. The plume is made so that there are no particles, or optionally if any particles were possible to be present, they are removed by a removal mechanism (not shown). The plume with the plume constituents in a plasma and/or vapour phase are fed 102 into the reactor, which can be actually of any suitable type for particle nucleation and growth, for instance embodied as an expansion chamber. The plasma constituents are allowed to cool 103 in the reactor so that the temperature is allowed to be decreased directly proportionally to the volume, while the exponential dependence of vapour pressure on the temperature is decreasing the saturation vapour pressure more rapidly so simultaneously increasing the saturation ratio. When the condition and constituent related saturation ratio is achieved, the nucleation occurs 104 in a very short time scale, even in μs or so, depending however the conditions. When the nucleation is finished, the particle size can still grow by condensation 105. The process can be maintained as long as the condensation favouring conditions allow the matter to condense on the particle surface. When growth is over, the particles can be captured 106 by impinging, diffusion or scrubbing techniques or by electrical collection means. Also combinations of electrical means and scrubbing can be used to make a liquid suspension of the particles. If other layers are desired, an appropriate plume material can be fed 107 into the zone of condensational growth in the reactor. So, even several layers can be made and the particle so produced could have finally an onion kind of structure, achieved by the several coating layers gained in the chain of condensation from various plumes produced by the method. The particles can be collected in several ways as a skilled man knows about known collection mechanisms for the appropriate particle size.
Figure 2 illustrates a method 208 of producing high-quality ablation plume by processing a target, on a target body, with a pulsed laser beam radiation according to an embodiment of the invention. As the figure demonstrates, the same method can be used for coating within the provision that the selected substrate 200 is coated 2007 with the plume material produced in the method phases 208. The method 208 comprises selecting 201 the target to be used for in the ablation, and the selection of the target material is applied for the embodiments that use the coating for the coating. In a carving like method, the plume material is not necessarily used for the coating of the substrate, but can be even wasted, or collected for circulation. The pulse energy is selected 202 for the ablation to match 203 the spot area to the maximum available in respect to exceed the ablation threshold sufficiently to have the plume and corresponding energy. The optics of the equipment is set 204 for the spot area size. The radiation, as pulsed, is scanned 205 on the target for the plume being formed from shallow ablation depth from the spot area by the ablation 206. In the coating method the plume material is used for the coating 207. The coating can be repeated with the same or another coating from a different target material as many times as required for the desired product.
The figure 3 illustrates a carving/grooving like method utilisation to make mere working with the target forming the product or a pre phase of it. The phase 302 in the method checks is the product ready after the phase 208. If the product is ready, and no more carving and/or coating were needed, the product is ready 301 and can be used or sold. According to the dashed lines, some products may still need a coating 207, although the carving was already made (the dashed Yes branch). Some products may need after a coating or few, further working to be made, illustrated by the dashed arrow from the coatings 207 to 208. As further patterns are to be made, the product may be not ready yet (No) and the further patterns 303 can made to the target or substrate. Is the product or substrate called as target or substrate depends on is it subject to the carving/grooving (target) or to coating (substrate). Thus, it is clear that a target can act as a substrate and vice versa.
An ensemble of examples on further embodiments
Figure 4 illustrates a cold work method according to an embodiment of the invention. The method has phase 6001 of selecting and/or exposing the target to be exposed to the radiation to ablate material along the ablation path on the target and the spot area therein. A radiation beam is directed to the selected target material in phase 6002 in order to expose a target material to the radiation at the spot area. According to an embodiment of the invention there can be also another target material to be ablated. Although drawn in parallel to phase 6003 the second ablation phase 6004 is not necessary a completely parallel phase, but can be a serial phase according to one embodiment.
Certain optionals of the coatings, related not only to the different aspects of the invention, is illustrated by the dashed lines. According to an embodiment in which the cold work is used for coating material formation, if substrate is addressed to be coated with coating. According to one embodiment of the invention the target can comprise a constituent of the coating, but part of the coating can be formed by the atmosphere at the substrate, and/or the substrate surface constituent or several constituents. According to another embodiment of the invention the target material is the same as the coating. The coating phase 6005 can be used as an only coating phase according to one embodiment, but the second coating phase 6006 illustrates that in another embodiment there can be several phases of coating to coat the substrate several times, completely or in suitable part. According to an embodiment of the invention the carving and coating phases can alter so at least partly remove parts of the just made coating to the ablation depth. This can be achieved by making the target to the substrate and/or vice versa to achieve the desired layers for the application.
According to an embodiment of the invention after each ablation and/or coating the method comprises a phase of checking if all the coating layers were already made. That is illustrated by the arrows directed as shown in figure backwards from higher reference numerated phases to the lower reference numerated phases.
The freedom to select of a coating 6011 for a phase 6003 and/or 6004, substrate 6010 and/or target material 6007 is illustrated by the periodic system of elements 6008, 6009. However, that is not limiting the said materials as such only to elements, although the target material is ablated. Also compounds of the elements can be used to be ablated. According to an embodiment, also organic material can be ablated, in order to form a coating thereof.
According to an embodiment of the invention, the body whose surface is to be carved, machined and/or coated by the cold-work according to an embodiment of the invention, said surface to be coated, can be a surface of a body per se or an already coated surface, or a surface at least partly coated, optionally or in addition in suitable part, such a surface that is indicated in a patent document FI20060182, to be incorporated herein by reference.
Fig. 5 illustrates an operation of a scanner to be used in the radiation path according to an embodiment of the invention. The scanner can have coated mirror surfaces with a high temperature tolerating reflective material, or totally manufactured from carbo-nitride and/or diamond in suitable part. Although figure 5 shows a conventional turbine scanner, the figure is not limiting the scanner type only to turbine scanner. In certain applications also non-conical round mirror scanners and/or wobbling scanners can be used for the scan, but especially for slow repetition rates and very large spot areas the scanner surface can be also that of a mirror scanner or a vibrating scanner being embodied.
The radiation source 1600 (not shown in Fig 5, but demonstrated by the beam 1510) can be embodied as a laser source embodied according to diode-pump of PDAD-system or any other cold ablation capable laser, i.e. with sufficiently powered laser, preferably with 100 W or larger in total power and having pulse length of pico-second, femto-second, or atto-second, with an inter-pulse pitch, and a pulse repetition rate adjustable up to larger than 20 MHz, advantageously up to larger than 50 MHz. The wavelength can be in the visible light region, but is not limited to that only. Although just one drawn, there can be also two or more radiation sources, operable in the same path in parallel or in series, which are not limited to the embodiment of similar source nor to that with all-different sources.
In Fig. 5, the radiation beam is reflected as a reflected beam 1503 via the scanner 1502 mirror surface to an optical lens 1501 , to the target 1400. In an embodiment, the target can have a smooth surface structure, roughened arbitrarily or so to have a certain surface structure optimized for the ablation and the coating formation, but in an embodiment in which the target is addressed to mere carving phase, the structure of the target may be unoptimized for the carving as such. The ablation path provided by the hit spots at the target is illustrated by H and the related number to illustrate also the scan on the surface of the target along the ablation path at the numbered points of the path. So, the H1 defines a moment when the beam 1503P, which can be polarized to a certain polarization by its production and/or the optics 1501 is directed to the spot area during a scanner cycle.
According to an embodiment of the invention, polarization of the beam can be used for the ablation optimum at the ablation path on the target surface, especially, if the polarization can be used for certain selectiveness of the ablation during a scan. The Fig. 5 demonstrate the scan points H1 , H2, H3, H4 and H5 which forms a series of arbitrary points from the scan path on the target, i.e. the beam path to produce on the target 1400 surface the ablation path as a queue of the spot areas. The scan path can be continuous, according to an embodiment, from the scanner mirror part edge to the next edge (i.e. with turbine scanner, but to the second position of the mirror in a non-turbine scanner of known type as such), but can be discrete according to another embodiment, as depending the exact repetition rate of the radiation source, and/or the rotation speed of the scanner 1502, in a certain fixed geometry. Also the inter-point times T1 , T2, T3, T4 and T5 are shown, and thus the movement / rotation direction is demonstrated.
The 1503Tr illustrates the beam part, which can go through the substrate in certain embodiments, for instance if the embodiments are used for a cut into the shape application and/or with partly transparent targets. The component 1503Tr thus can be used for the estimating of even each individual pulse intensities and thus for the quality monitoring. However, in carving of metals for instance the 1503Tr can be neglibly small or a zero component at the drawn side. However, that component may be replaced an available reflection at the same side as the incoming radiation. In Fig.5 the beam 1510 formed in the radiation source meets an expander 1508, which expands the beam to tapered shape, then the collimator unit 1507 to form a curtain-like broad but thin radiation wedge to be deflected by the turbine scanner 1502, through the correction optics 1501 optionally or in addition to polarization operation so that the beam 1503P hit the ablation target 1400 at the H1. The correction optics can be thus used to define the spot area with its characteristic measure, as the diameter for instance, for the spot area on which the ablation threshold is exceeded, but of which the adjusting of the spot area to size in which the ablation threshold is slightly exceeded throughout the spot area with the provision of the pulse energy to being supplied.
Fig. 6 illustrates an arrangement 5700 according to an embodiment of the invention. The example shown comprises a radiation source 5701 and/or another radiation source 5707. The number of the sources as such is not limited only on one or two. In the arrangement, there is also indicated the target 5706, which can be target material according to an embodiment of the invention, or a target to be cold-worked. Fig. 6 also illustrates radiation path 5703 as arranged to guide radiation from a radiation source 5701 to the target 5706, to be used for ablating the target material from the spot area. The path comprises a scanner 5704, but the number of scanners per path is not necessarily limited to the shown only. The figure illustrates adapter 5702, 5705 arranged to adapt the path 5703 to the source 5701 and the target 5705, respectively. The adapter can comprise an expander, contractor and/or correction optics parts, which are necessary for the focussing in such embodiments, in which the geometrical beam shape is necessary to change in the path from the source to the target for the desired spot area size.
Fig.6 also embodies such variations of the arrangement 5700 in which there is also an additional source 5707 to be used in parallel and/or in addition to the source 5701. The additional source can be exactly the same according to one embodiment but according to another a different one. According to one embodiment, the source is a heater arranged to heat the target. The adapter 5708 can be the same as 5702, but is not necessary such. It can be also an integrated adapter as an expander. The scanner 5709 can be same as the scanner 5704, but is not limited only thereto. The scanner is a turbine scanner according to an embodiment of the invention. According to the way of drawing, the adapter 5710 is arranged so that the radiation from source 5707 arrives to the target 5706, as the radiation from the source 5701. The arrangement do not necessary need the adapters at all, provided that the geometry of the beam directed via the scanner is sufficiently uniform and/or in correct focus to yield the spot area the necessary fluence to exceed the ablation threshold value; above, beneath or on the surface of the target material or its base. The radiation of the radiation source can be in one embodiment directed to several targets, although only 5706 shown as an example.
Fig. 7 illustrates a prismatic low-faced turbine scanner 3321 , but especially the rotor part of it 3321. The part 3321 can be a conventional turbine scanner part, but also a part according to an improved embodiment of the invention, provided with at least a coating of the mirrors with high durability for the high laser power pulses, as with diamond coating for instance. In the example of the figure, the part 3321 has faces 3322, 3323, 3324, 3325, 3326, 3327 and 3328. The arrow 3320 illustrates the rotation of the part 3321 around the axis 3103. The faces are mirrors, each of which in-duty, arranged by its own turn, to deflect the incoming radiation beam via the radiation path and to cool when the mirror is off-duty. Tilt angles of the faces are shown for various embodiments. The Fig. 7 illustrates one revolution of the turbine scanner part in time scale from the first mirror, mirror 1 , to the last mirror, mirror 8. An ablation path on the target can be thus demonstrated. The ablation path is indicated to hit the target, which can be any target to be cold- worked, at the right by reference 3329, but in the left indicated with the same reference number the scanning path to be used to provide the ablation path. The return of the beam is indicated by the line 3330. The mirrors are indicated by the apparent reference number. Although 40-μm-scan line has been demonstrated as an example, embodiments of the invention are not limited only to shown beam size and/or shape. The beam can be also as a line in an embodiment. The location of the scan line on the target material may be the same in one embodiment for at least two successive scans, but the scan line for two successive scans can be different in another embodiment, if for example, the material is likely to form fragments even in cold-work based on ablation. The number of faces is not limited to the 8, which is only an example in the figure. Faces can be of tens or even hundreds in number, however, influencing possibly to the scan line length. The scanner mirrors can be also curved, although not shown in the Fig.7. The corners can be rounded according to an embodiment of the invention.
In one embodiment of the invention number of different scan lines at the target surface can be achieved by variation of the tilt from face to the next face of the turbine scanner, or in another embodiment by changing the face tilt of at least one mirror or several mirrors. The turbine scanner has an advantage that the beam won't stop one location at the target and thus the yield is rapid and homogenous during a scan resulting from a homogenous plume from the target.
The size of the turbine scanner is freely scalable for a skilled man in the art who has read the application text. The embodiments comprise variations of microscopic scaled to macroscopic scale so that in the macroscopic scale according to one embodiment the diameter is about 12 cm and height 5 cm. The distinction of low-faced turbine scanner from a high face turbine scanner can be made by the measures of the height of the mirror in an axial direction in relation to the width of the mirror in a perpendicular direction of the axial direction. If the height and width are essentially the same, or exactly the same such an intermediate embodiment is included to either low- or high- faced embodiment according to the ratio so that if the height is smaller than the width, it is low-faced but if the height is larger than the width it is high-faced.
It is advantageous to use turbine scanner in the radiation path for such systems in which use a pico-second laser systems whose repetition rate is above 4 MHz, advantageously over 20 MHz and/or the pulse energy is above 1 ,5 μJ. However, other type of scanners can be used with low repetition rates down to few 500 Hz form say 500 kHz.
It is also advantageous to control the radiation power at the hit spot, i.e. at the spot area on the target, according to the possibilities. Thus, even each pulse can be evaluated and the knowledge on the departures of the pulse/radiation properties from pre-defined values can be used in a feed-back loop for controlling the radiation beam focus, the ablation of target material, substrate coating, and/or the plume formation.
Figure 8A illustrates an embodiment of the invention. The measures are not necessarily in scale. In the middle, The spot area has a characteristic measure AB as a diameter, which much larger than the shallow ablation depth. The pulsed laser source is indicated by the source, the beam being scanned with a mirror surface of the scanner to the round spot area with the diameter A-B. The left hand side of diagram, an ablation threshold is marked as well as locations A and B on the surface of the target. At the right hand side it is there illustrated, that with a shallow ablation depth and large spot area the yield (Y) and quality (Q) can be improved in comparison to same kind of scenario in Figure 8B with a smaller spot area with smaller diameter |CD| and larger ablation depth (<|CD|<|AB|). An example on the radiation source
The radiation source to be used in the arrangement according to an embodiment of the invention can comprise at least one or several diode-pumped radiation sources and each radiation source can have an optical path of its own, but not necessarily the same as another. According to an embodiment the radiation is laser radiation originating to radiation source arrangement according to an embodiment.
A radiation source arrangement according to an embodiment of the invention to be used for the pulsed radiation laser beam comprises a first feature and/or a second feature, which is at least one of the following:
- (i) the wavelength characteristic to the radiation source,
- (ii) on-duty pulse length,
- (iii) length of off-duty period between two successive pulses,
- (iv) repetition rate of the on-duty occurrences,
- (v) radiation intensity,
- (vi) energy and/or power per pulse,
- (vii) polarization of the radiation, and
- a combination of at least two or more of the features (i)-(vii).
According to an embodiment of the invention said first feature is different than said second feature. According to an embodiment said feature is considered as an aspect of a radiation source.
A radiation source to be used in the arrangement according to an embodiment of the invention has at least one radiation source which is arranged to produce radiation having a wave length in range which wave length is at least one of the following:
- wavelength between a radio wavelength and an infrared wavelength,
- wavelength in infrared,
- wavelength of visible light, - wavelength of ultraviolet, and
- wave length of X-rays.
According to one embodiment of the invention the optical path is arranged to comprise at least one path for plurality of radiation sources comprising at least one radiation source arranged to direct at least one radiation beam to a plurality of targets comprising at least one target. If an embodiment is using intermittent pulsing for the cold working, the intermittency can be arranged in periodical way by using several sources each having own period, to be superposed at the hit point of the ablation path.
According to an embodiment, the laser source can be embodied, optionally or in addition, in suitable part according to the patent document FI20060182 incorporated herein by reference.
One further example embodies a laser arrangement according to an embodiment of the invention. The mentioned parameter values are examples, and are thus not restrictive only to the mentioned values. The turbine scanner as embodied is only an example, and thus not restrictive.
Figure imgf000030_0001
Smooth operated, Velocity 0.. 4000 m/s, or linear beam movement, B higher, high laser power, typically 50 ..100 m/s or vacuum and/or TURBINE SCANNER, higher, for turbine scanner, atmosphere optionally other scanner values may be lower for other types
Figure imgf000030_0002
Layer-structures, each control rang 0,5μJ...15 JJ layer formed from the D fast, max 1 μs same or different AUTOMATIC PULSE pre-progammable, materials ENERGY/POWER quality control even to
CONTROL SYSTEM micro-scale
Figure imgf000031_0001
+
The shorter wave-length 1064 nm, the better yield F 293.. .420 nm,
LASER RADIATIOIN 420.. .760 nm
WAVE LWNGTHS other wave lengths
Figure imgf000031_0002
Pico-second laser system (A) + Scanner (B) + target feed (C) as lamellas or film, in such applications where needed for coating for instance, yield high quality products and/or surfaces of large amounts. The products can be of single crystalline diamond and/or silicon to be used as a substrate for semiconductor industry for instance, produced in vacuum, or in a gas atmosphere.
The coating can be formed on a surface of any kind, for example, on metal, plastics and/or paper to mention few. In one embodiment the coating has a coating layer thickness of 5 μm. The semiconductor material can be silicon as pure or as a compound, but in a flexible form, suitable into use of electronics, micro and/or nano-electronics. The points D, E, F and G help the manufacturing of high quality products in industrial scale, repeatable and promote the quality control.
Examples on products to be coated or being coated
Products that comprise surfaces and/or 3D materials having various functions can be produced in accordance with the invention. Such surfaces include e.g. very hard and scratch-resistant surfaces and 3D materials in various glass and plastic products (lenses, monitor shields, windows in vehicles and buildings, glassware in laboratories and households); various metal products and their surfaces, such as shell structures for telecommunication devices, roofing sheets, decoration and construction panels, linings, and window frames; kitchen sinks, faucets, ovens, coins, jewels, tools and parts thereof; engines of automobiles and other vehicles and parts thereof, metal cladding in automobiles and other vehicles, and painted metal surfaces; objects with metal surfaces used in ships, boats and airplanes, aircraft turbines, and combustion engines; bearings; forks, knives, and spoons; scissors, hunting knives, rotary blades, saws, and all types of cutters with metal surfaces, screws, and nuts; metallic processing means used in chemical industry processes, such as reactors, pumps, distilling columns, containers, and frame structures having metal surfaces; piping for oil, gas, and chemicals; parts and drill bits of oil drilling equipment; pipes for transporting water; weapons and their parts, bullets, and cartridges; metallic nozzles susceptible to wear, such as papermaking machine parts susceptible to wear, e.g. parts of the coating paste spreading equipment; snow pushers, shovels, and metallic structures of playground equipment; roadside railing structures, traffic signs and posts; metal cans and vessels; surgical equipment, artificial joints, and implants; cameras and video cameras and metallic parts in electronic devices susceptible to oxidation and wear, and spacecraft and their cladding solutions resistant to friction and high temperatures.
Yet other products fabricated in accordance with the invention may include surfaces and 3D materials resistant to corrosive chemical compounds, semiconductor materials, LED materials, pigment materials and surfaces made thereof which change color according to the viewing angle, parts of laser equipment and diode pumps, such as beam expanders and the light bar in the diode pump, jewel materials, surfaces of medical products and medical products in 3D shapes, self-cleaning surfaces, various products for the construction industry such as pollution- and/or moisture-resistant and, if necessary, self-cleaning stone and ceramic materials (coated stone products and products onto which a stone surface has been deposited), dyed stone products, e.g. marble dyed green in accordance with an embodiment of the invention or self-cleaning sandstone.
The invention shows a method of producing high-quality ablation plume by processing a target, on a target body, with a pulsed laser beam radiation, so that the method comprises: selecting a spot area for a beam cross-section on the target to correspond the ablation threshold of the target material to being exceeded throughout the spot area of which the plume is ablated by the pulsed beam radiation within a controlled ablation depth so providing the fine quality plasma, to be used for coating and/or particle synthesis.

Claims

Claims
1. A method of producing high-quality ablation plume by processing a target, on a target body, with a pulsed laser beam radiation, is characterized in that the method comprises: selecting a spot area for a beam cross-section on the target to correspond the ablation threshold of the target material to being exceeded throughout the spot area of which the plume is ablated by the pulsed beam radiation within a controlled ablation depth.
2. A method of claim 1 , wherein the method further comprises at least one of the following:
- selecting pulse energy, for a pulse of a pulsed laser beam radiation, to be distributed on to a spot location at the target, and to essentially exceed an ablation threshold fluence of the target material throughout the spot area so defined,
- setting an optical path for directing said laser beam radiation to meet said spot area with said fluence,
- scanning said pulsed laser beam radiation on the target surface for defining a location of the spot with said spot area to be ablated from the target surface,
- ablating at the location of said spot, the material from the spot defined by said scanning, to an ablation depth, with said pulsed laser beam into a plume.
3. A method of claim 1 wherein the scanning is implemented in the method by a turbine scanner.
4. A method of claim 1 wherein the scanning is implemented in the method by a vibrating and/or mirror scanner.
5. A method of claim 1 wherein the area of the spot area is defined in the method by a characteristic which is at least one of the following: ablation depth, a diameter of the spot, a perimeter of the spot defined along a closed equal-fluency- line and the volume of the material to be ablated.
6. A method of claim 1 , wherein the plume is made for forming a pattern on a target surface with a smooth surface feature that is at least one of the following: a smooth carving path, a smooth cut line, a smooth pattern on the surface.
7. A method of claim 1 , wherein the spot area is set to its characteristic size at the target for pulse energy that is larger than 5 μJ for an individual pulse.
8. A method of claim 7, wherein the spot area is set to its characteristic size for pulse energy that is larger than 10 μJ for an individual pulse.
9. A method of claim 8, wherein the spot area is set to its characteristic size for pulse energy that is larger than 50 μJ for an individual pulse.
10. A method of claim 9, wherein the spot area is set to its characteristic size for pulse energy that is larger than 100 μJ for an individual pulse.
11. A method of claim 10, wherein the spot area is set to its characteristic size for pulse energy that is larger than 200 μJ for an individual pulse.
12. A method of claim 11 , wherein the spot area is set to its characteristic size for pulse energy that is larger than 500 μJ for an individual pulse.
13. A method according to any one of the claims 1 -12, wherein the spot area is set to its characteristic size for pulse energy that is less than 500 000 μJ for an individual pulse.
14. A method according to any one of the claims 1 -13, wherein the spot area is set to its characteristic size for pulse energy that is less than 5 J for an individual pulse.
15. A method according to any one of the claims 1 -14, wherein the repetition rate of the pulses is larger than 20 kHz.
16. A method according to any one of the claims 1 -15, wherein the repetition rate of the pulses is larger than 200 kHz.
17. A method according to any one of the claims 1 -16, wherein the repetition rate of the pulses is larger than 2 MHz.
18. A method according to any one of the claims 1 -17, wherein the repetition rate of the pulses is less than 10 MHz.
19. A method according to any one of the claims 1 -18, wherein the medium has a phase of at least of the following:
- a gas that has a state from at least one of the following:
--in high pressure,
--in normal pressure,
--in under pressure and
--in practical vacuum,
- a liquid, and
- a multiphase medium comprising liquid phase and a gas phase with gas that has a state.
20. A coating method characterized in that the substrate to be coated in the method, with a smooth coating comprises a method of surface processing according to any one of the claims 1 -19 for achieving a plume to be used for the smooth coating formation on the substrate.
21 , A coating method according to claim 20, wherein the spot at the target is further defined by the adhesion with the substrate.
22. A coating method according to claim 20 or 21 , wherein the spot at the target is further defined by the optimization criteria of particlelessness of the plume.
23. A coating method according to any one of the claims 20-22, wherein the coated substrate surface comprises less than a pinhole per 1 mm2, preferably less than one pinhole per 1 cm2, even more preferably a pinhole per 1 km2, but most preferably no pinholes at the surface on the substrate body to be coated.
24. A coating method according to any one of the claims 20-23, wherein the coated substrate surface is coated in such a manner wherein the first 50 % of the product surface layer does not contain any particles having a diameter exceeding 1000 nm, preferably 100 nm and most preferably 30 nm.
25. A coating method according to any one of the claims 20-24, wherein the average surface roughness of produced articulating surface layer is less than 100 nm as scanned from an area of 1 μm2 with an Atomic Force Microscope (AFM).
26. A particle making method, characterized in that in addition to the method according to any one of the claims 1 -19, the method has a cooling phase for cooling the plume in the medium for producing particles via a nucleation phenomena.
27. A method according to claim 26, wherein the cooling in the method is made for a nucleation phenomena comprising at least one of the following:
- ion induced nucleation within the medium having charged material present to use the ions as the seed-nuclei,
- homogeneous nucleation,
- heterogeneous nucleation within the medium having presence of nucleation seeds for the nucleation to occur on a surface.
28. A method of claim 27, wherein the nucleated particles are grown by condensation of the material originating to the plume.
29. A method of claim 27 or 28, wherein the plume is diluted for preventing aggregate formation, and/or the particle coalescence.
30. A method according to any one of the claims 1 -22, wherein the material of the plume comprises of at least one of the following inorganic constituents of the plume: ions, plasma constituents, atoms, molecules, nano- particles smaller than 10 nm in size.
31. A method according to any one of the claims 1 -22, wherein the material in the plume comprises of inorganic constituents for forming a ceramic coating or ceramic-like coating.
32. A method according to any one of the claims 1 -31 wherein the radiation source is a hot ablation laser source.
33. A method according to claim 32, wherein the laser source comprises at least one nanosecond laser.
34. A method according to any one of the claims 1 -31 , wherein the radiation source is a cold ablation laser source.
35. A method according to claim 34, wherein the laser source comprises at least one of the following: a pico-second laser, a femto-second laser and an atto-second laser.
36. A method according to any one of the claims 1 -22, wherein the material in the plume comprises of organic cells and/or their constituents.
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