KR20200094041A - Apparatus and Method for generating pulse for amplifying maximum output of laser - Google Patents

Abstract

The present invention relates to a pulse forming apparatus for laser maximum output amplification, and a method thereof. According to the present invention, the pulse forming apparatus for a laser′s maximum output amplification comprises: a laser light source for generating a laser; a circular overlapping module; and a pulse generation module arranged on a path of the circular overlapping module. According to the present invention, the laser processability can be improved by significantly increasing the maximum energy density.

Description

{Apparatus and Method for generating pulse for amplifying maximum output of laser}

The present invention relates to an apparatus and method for forming a pulse to amplify the instantaneous maximum power of a laser. The laser can be roughly divided into gas, liquid, and solid lasers depending on the type of the medium that generates the laser with light with high straightness and energy, and usually has an average maximum power and an instantaneous maximum power expressed by W. The present invention relates to a pulse forming apparatus and method for amplifying the maximum power to amplify the maximum instantaneous power among the outputs of such lasers.

The laser is based on the first letters of Light Amplification by Stimulated Emission of Radiation and has high straightness and energy. Basically, atoms and molecules have several levels of energy levels, and when heat or other energy is applied to atoms or molecules, they are excited as unstable high-level energy levels, and then returned to stable low-level energy levels. Gives At this time, when the generated light collides with an atom, the atom is induced to emit the same radiation with the same phase as the wave that stimulated it. Since the laser emits light of a single frequency or a single wavelength by using this principle, it has a high energy density. And straightness.

Since the laser has such high energy density and straightness, focusing with a focusing lens or the like can irradiate very high energy to a very small area. It is used to cut or weld metal, to change the surface properties of materials, and to be used in medical fields such as skin care, ophthalmic surgery. In addition, a small area of the sample can be brightly illuminated by using a high density of light, which is also used as a light source for a microscope.

In the fields of cutting, welding, and surgery, the laser that arrives at the processed material usually converts light energy into thermal energy and is processed by thermal energy. At this time, not all lasers that reach the processing material are used for the desired work, some are reflected, some are turned into heat and flowed to the surroundings, and only the other part is used for necessary work such as cutting and welding. Normally, the amount of laser light reflected by the cutting and welding of a smooth metal is very high before the surface to be processed is broken, but after the surface is broken, it is diffusely reflected and absorbed by the processing part, and thus has a characteristic of dropping rapidly. In addition, the amount of heat flowing around the processing section has a characteristic proportional to the irradiation time when the energy used for processing is the same. Therefore, the same energy should be irradiated in a short time in order to perform processing with less thermal deformation in cutting and marking of metal.

Cutting and marking using a laser is a process of evaporating and removing the material of the processing part. When the laser output is low, the material stays relatively longer in the melting stage than evaporation, and the molten part is attached to the base material to be processed, and the energy injected by the laser is converted into heat and flows to the surroundings. Therefore, in order to evaporate the same amount of material, more energy injection is required as much as the heat energy flowing to the surroundings. For this reason, if the laser power is cut in half, the processing time is much longer, more than double.

The laser is divided into a continuous emission laser and a pulse emission laser according to the output type. Since the pulse emission laser amplifies the laser by using resonance, the maximum instantaneous output power is high even if the average power is the same as that of the continuous emission laser. When the average output power is the same, pulsed lasers can perform faster processing with less thermal distortion than continuous lasers.

In recent years, many lasers having a pulse width shorter than picoseconds and femtoseconds have emerged. Picosecond lasers and femtosecond lasers basically use a laser mode lock technique and a technique of dispersing and amplifying and overlapping various combinations of light having different wavelengths through time delay. However, it is possible to obtain a high instantaneous power by manipulating in a short time in which light is only 0.3 mm in the air, but it is very difficult to obtain a high average power. The average power of these lasers on the market is mostly about 100 watts or less. In addition, it is difficult to see a single wavelength laser in a strict sense because it uses a combination of light with different wavelengths. These lasers are also very expensive, making them difficult to use for a variety of purposes, such as metal cutting and welding, and glass and ceramic processing. Therefore, it is necessary to develop a new method for obtaining a laser output having a short pulse width, a high output, and a single wavelength.

The present invention is to solve the above problems, by amplifying and supplying the instantaneous output of the laser, it is possible to obtain the same effect as a high-power laser even with a low-power laser, and amplify the instantaneous output of the laser as much as desired without additional energy supply. The present invention provides a pulse forming apparatus and method for amplifying a laser instantaneous maximum power capable of performing ultra-high-density laser processing that could not be processed due to the limitations of the maximum instantaneous laser power.

In order to achieve the above object, the pulse forming device for amplifying the laser maximum power of the present invention is a device for amplifying the maximum laser power, in which the laser light source generating the laser and the laser light generated from the laser light source are incident. A cyclic superposition module that overlaps with different number of cycles, and a pulse generation module that is provided on a path of the cyclic superposition module and simultaneously reflects two or more lasers circulating in the cyclic superposition module according to a preset cycle. Includes.

In addition, the cyclic superposition module is characterized by consisting of two or more mirrors for changing the path of the circulated laser.

In addition, the two or more mirrors are characterized in that they are arranged at a predetermined angle for each mirror for reflecting each laser so that the planes circulated according to the number of cycles do not overlap each other.

In addition, the pulse generation module is characterized in that it comprises a polarizing mirror that passes/reflects according to the EOM and the polarization to simultaneously reflect two or more lasers circulating in the cyclic superposition module.

In addition, in order to achieve the above object, the pulse forming method for amplifying a laser maximum power of the present invention is a pulse forming method for amplifying a laser maximum power, generating a laser from a laser light source, and generating from the laser light source The step of circulating the overlapping by injecting the lasers into a circulating superposition module having a different number of cycles according to the order of incidence, and generating pulses provided on two or more lasers circulating in the cyclic superposition module on the path of the cyclic superposition module And reflecting at the same time according to a preset period using the module.

In addition, in the step of cyclically overlapping the incident laser, it is circulated using a cyclic type superposition module composed of two or more mirrors for changing the path of the circulated laser, but the two or more mirrors are circulated according to the number of cycles It is characterized in that the mirrors are disposed at a predetermined angle for each mirror to reflect each laser so that the planes do not overlap with each other, thereby cyclically overlapping.

In addition, in the step of reflecting at the same time, the pulse generating module provided on the path of the circulating superposition module simultaneously reflects two or more lasers that are circulating using a polarizing mirror that passes/reflects according to the polarization of the EOM and the laser. It is characterized by.

According to the present invention having the above-described configuration, even when a laser having the same power is used, the maximum energy density can be significantly increased to improve the processability of the laser.

In addition, as the maximum power is amplified and emitted using a laser having the same power, thermal deformation occurring around the processing portion during processing of the workpiece can be minimized.

In addition, even if the laser of the same output is used, it is possible to minimize the amount of energy that changes into heat around the processing part, so that faster processing can be performed.

In addition, by overcoming the problem of the laser, which currently has a limitation in the maximum output, amplification to the desired output is possible, so that ultra-high integration processing is possible.

In addition, there is an advantage in that the maximum power can be obtained as much as desired with a simple configuration.

1 is a schematic block diagram of a pulse forming apparatus for laser maximum power amplification according to an embodiment of the present invention,
2 is a view showing a process in which a pulse with an output amplified is formed in a pulse forming device for amplifying a laser maximum power according to an embodiment of the present invention,
3 is a view for showing the output before and after being modulated by the pulse generator for amplifying the maximum output according to an embodiment of the present invention,
Figure 4 shows the process of amplifying the maximum output according to an embodiment of the present invention over time,
5 is a view for explaining the principle of operation of the Q-switch consisting of an EOM and a polarization reflection mirror that is an example of the pulse generation module of the present invention,
6 is a flowchart of a pulse forming method for amplifying a laser maximum power according to an embodiment of the present invention.

Hereinafter, a pulse forming apparatus and method for maximum laser power amplification according to the present invention will be described in detail with reference to the drawings.

1 is a schematic block diagram of a pulse forming apparatus for amplifying a laser maximum power according to an embodiment of the present invention.

The pulse forming apparatus and method for amplifying the maximum power of the laser of the present invention is a device for amplifying the maximum power of the laser, and the maximum power of the laser is usually designated as W, and the present invention is not the maximum power, more precisely, the average power. It is a device that amplifies the maximum output.

The pulse forming device for amplifying a laser maximum power of the present invention is a pulse forming device for amplifying a maximum instantaneous maximum power in a pulse form, and more specifically, a laser light source 100 generating a laser for amplifying the maximum output. By varying the number of times the laser generated from the laser light source 100 is incident and circulated according to the order in which it was incident, it is provided in the path of the cyclic superposition module 200 and the cyclic superposition module 200 in which multiple lasers are circulated and overlapped. It comprises a pulse generation module 300 for reflecting and emitting two or more lasers circulated in the cyclic superposition module 200 according to a preset period at the same time.

The laser light source 100 of the present invention is configured to generate a laser, and atoms have energy levels of several stages and emit radiation having the same phase as the wave that stimulated them, and the laser emits radiation of these atoms. It is caused by induction. Depending on the medium that induces radiation, lasers are largely divided into solid, liquid, gas, and semiconductor lasers. Examples of solid lasers include ruby lasers containing chromium ions, YAG lasers using yttrium aluminum garnet, and liquid lasers are dye lasers. The gas laser is a CO2 laser. Semiconductor lasers are lasers that generate lasers using semiconductors, which have the advantage of being compact, but have the disadvantage of small output and poor directivity.

The pulse forming device for amplifying the laser maximum power of the present invention can amplify the maximum power regardless of the type of laser, but can more efficiently perform the maximum power amplification of the CW (Continuous Wave) laser than the pulse laser. This is because the pulse laser emits energy in a pulse form of a specific cycle, so that it must match a pulse of a specific cycle to amplify the maximum output. Of course, the pulse laser can also amplify the maximum output by adjusting the preset period in the pulse forming module 300 to the pulse width of the laser light source 100 or a multiple of the pulse width.

The circulating superposition module 200 of the present invention is a configuration in which the laser generated from the laser light source 100 is incident and circulated, so that the number of cycles is varied according to the order in which it is incident, so that multiple lasers are circulated. That is, when the number of cycles, such as two or three times, and the plane through which the laser circulates is circulated, is changed, the circulated surface is changed.

This configuration will be described in more detail through the example shown in FIG. 1. The circular superposition module 200 according to the embodiment of FIG. 1 is composed of four reflective mirrors 210. The four reflection mirrors 210 of the cyclic superposition module are configured such that the laser from the laser light source reflects once or several times, and then returns to the first reflected mirror, but reaches the mirror when it returns to the first reflective mirror. The position to be made is configured to reach while maintaining parallel with the laser light source that first enters the circulating superposition module 200, although the diameter size of the diverging laser beam will be different compared to the first. In addition, after the laser is circulated once, the reflection mirror 210 is arranged to be slightly shifted up and down or left and right from the original incident position, so that the circulating plane is changed when the number of cycles is changed. In the present invention, the process of circulating one or more times in the circulating superposition module 200 and two or more laser loops in parallel approach is referred to as a “circulation overlapping process”. It is configured such that two or more laser loops are present in at least one portion of the circulating overlapping module 200 by repeating the “cyclic overlapping process” one or more times. In the embodiment of FIG. 1 or 2, the overlapping process is performed three times with four reflection mirrors 210, but the number of overlaps and the number of reflection mirrors 210 may be changed.

The pulse generation module 300 of the present invention is configured to reflect multiple lasers circulating in the circulating superposition module 200 at the same time and to emit the cyclic superposition module 200 to the outside. An example of the pulse generation module 200 is shown in FIG. 1 or 2, and the pulse generation module 300 of FIGS. 1 and 2 is a combination of an EOM 310 and a polarization reflection mirror 320, which are a type of Q-switch. consist of. Referring to the left figure of FIG. 2, there are three circulating lasers in the left and the pulse generating module 300 is operated in the right figure, and the three circulating lasers are reflected and emitted simultaneously. This was described in more detail in FIG. 5. The EOM 310 is a type of optical element using an electric field optical phenomenon, and is made of a material having a crystal structure without central symmetry, and when an electrode is installed at both ends and a voltage is applied, an electric field is formed inside the crystal structure, and birefringence occurs. This appears, and the polarization direction of the incident beam is changed to a direction perpendicular to the incident beam. In addition, in a region in which a uniform electric field is formed, the degree of property of changing the polarization direction has the same characteristics. The polarization reflection mirror 320 is installed to pass a laser when polarization is not changed and to reflect when it is vertically changed. The lasers superimposed one or more times by the cyclic superposition module 200 according to one embodiment of FIGS. 1 and 2 are configured to pass through the inside of the active area of the EOM 310. When the Q-switch is on, it means that a voltage is applied to the EOM 310.

In one embodiment of FIG. 2, if the Q-switch is kept off, the laser continues to circulate in the circulating superposition module. In FIG. 2, since the circulating superposition module 200 maintains a state in which the EOM 310 of the Q-switch is off in the process of being cycled up to 2 times, it passes while maintaining the original pulse waveform. Then, when the Q-switch is turned on twice during the “circulation overlapping process” and then the next Q-switch is turned on during the “cycling overlapping process”, three circulating lasers are polarizing reflection mirrors (320 ) Is reflected and emitted at the same time, so a laser pulse overlapped three times exits the circulating superposition module 200.

If these three "cycles overlapping repeatedly" cycles are repeated repeatedly, as shown in Fig. 3, the width becomes one time of "cycles overlapping", and the maximum power of the laser can obtain a pulse that is three times the original. . In FIG. 3, the pulse generated according to the operation of the Q-switch of FIG. 2 is illustrated to be understood in terms of time and space.

In addition, in the embodiment of FIG. 2, a laser that is continuously oscillated was described, but the present invention is not limited to this, and a laser having a pulse-type output also produces shorter pulses and higher maximum output by the device of the present invention. It can be changed into an excitation laser.

In addition, although the pulse generation module 300 has been described as an example in FIGS. 1 and 2, two or more Q-switches may be provided. This is because it may be difficult to amplify with one Q-switch depending on the degree of overlap, the beam size of the laser to be amplified, and the output of the laser. Even if multiple Q-switches are used, it is important to arrange each Q-switch so that the paths of the circulating lasers do not overlap each other, and it is important to control each Q-switch to operate simultaneously because it is necessary to simultaneously reflect for amplifying the output. It is important.

FIG. 4 is an example of a case in which the time of “the process of cyclically overlapping” is 10 ns once in the embodiment of FIG. 2 and shows where the differently displayed lights are separated by a time interval of 10 ns. Each of the blue (single-dot chain), red (double-dot chain), and black (three-dot chain) light sequentially enters the interior of the cyclic type overlapping module 200 sequentially and simultaneously by the operation of the pulse generating module 300. Will come out.

5 relates to a Q-switch that is an embodiment of the pulse generation module 300 of the present invention. Generally, the operating time of the commercially available EOM 310 element is about 300 to 800 picoseconds. Therefore, when using a commercially available Q-switch as the pulse generation module 300 of the present invention, it is possible to make a laser pulse having a width of 300 to 800 picoseconds.

Fiber lasers and CO2 lasers are frequently used for cutting and welding metals. Due to the nature of the metal, it has a high melting point and is often thick, so high energy is required, because there are many fiber lasers and CO2 lasers available for high power output. However, in the case of a fiber laser, it is difficult to make a laser having a pulse width of 100 ns or less because the distance between both reflection mirrors of the laser resonance oscillation unit is long, and the CO2 laser is difficult to make a pulsed output due to the characteristics of a gas laser. Therefore, welding and cutting using these lasers cause a lot of heat distortion around, and thus have a problem in processing quality, and cannot be used when heat deformation must be strictly limited.

Using the pulse generator for amplifying the maximum power of the present invention, these lasers can be changed to lasers having a smaller pulse and a higher maximum power to overcome the above problems.

6 is a flow chart showing a pulse forming method for amplifying a laser maximum power of the present invention. Hereinafter, a pulse forming method for amplifying a laser maximum power will be described, but a description overlapping with the above description will be omitted.

In the pulse forming method for amplifying a laser maximum power of the present invention, first, a laser for amplifying the maximum power is generated and emitted from the laser light source 100. (S100) The laser emitted from the laser light source 100 is a circular overlapping module ( 200), the circulating superposition module 200 is a module configured to vary the number of circulating cycles according to the order of incidence. (S110) Two or more lasers circulating in the cyclic superposition module 200 are on the path. Through the provided pulse generation module 300, it is reflected simultaneously according to a predetermined predetermined period. (S120) As the number of lasers circulated is reflected, the pulse with the maximum output amplified is emitted.

Laser light source: 100 Circulation superposition module: 200
Pulse generation module: 300

Claims (7)

In the device for amplifying the maximum laser power,
A laser light source generating the laser,
A circulating type superposition module that superimposes the laser generated from the laser light source by varying the number of cycles according to the order of incidence;
A pulse forming device for maximum laser power amplification, comprising a pulse generating module provided on a path of the circulating superposition module and simultaneously reflecting two or more lasers circulating in the cyclic superposition module according to a preset cycle.
In claim 1,
The cyclic superposition module is a pulse forming device for amplifying the laser maximum power, characterized in that it consists of two or more mirrors for changing the path of the circulated laser.
In claim 2,
The two or more mirrors are arranged at a predetermined angle for each mirror for reflecting each laser so that the planes circulated according to the number of cycles do not overlap each other.
In claim 1,
The pulse generating module comprises a polarization mirror that passes/reflects according to polarization and EOM to simultaneously reflect two or more lasers circulating in the circulating superposition module. Device.
In the pulse forming method for amplifying the maximum laser power,
Generating a laser from a laser light source,
Circulating the laser generated by the laser light source into a cyclic type superposition module having a different number of cycles according to the order of incidence;
A method of forming a pulse for a laser maximum power amplification, comprising simultaneously reflecting two or more lasers circulating in the cyclic superposition module at a predetermined period using a pulse generation module provided on a path of the cyclic superposition module.
In claim 5,
In the step of circularly overlapping the incident laser,
Each mirror for reflecting each laser so that the two or more mirrors are circulated according to the number of cycles, so that the planes circulated according to the number of cycles do not overlap each other using a cyclic type overlapping module composed of two or more mirrors for changing the path of the circulated laser. Pulse forming method for laser maximum power amplification, characterized in that it is arranged at a predetermined angle for each cycle and cyclically overlapped.
In claim 5,
In the step of reflecting at the same time,
The pulse generation module provided on the path of the circulating superposition module is for laser maximum power amplification, characterized in that it reflects two or more lasers circulating at the same time using a polarization mirror that passes/reflects according to the polarization of the EOM and the laser. Pulse formation method.

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