WO2025147289A2 - Laser assembly with offset lens array and angular insensitive output coupler - Google Patents

Abstract

A laser assembly (10) includes an emitter array (34) and a lens array (36). The emitter array (34) includes a first emitter (18A) that generates a first emitter beam (20A) along a first emitter axis (44A), and a second emitter (18B) that generates a second emitter beam (20B) along a second emitter axis (44B). The first emitter axis (44A) and the second emitter axis (44B) are spaced apart a first emitter separation distance (42a). The lens array (36) includes a first lens (22A) that colliminates the first emitter beam (20A), and a second lens (22B) that colliminates the second emitter beam (20B). The first lens (22A) has a first lens axis (48A) and the second lens (22B) has a second lens axis (48B). The first lens axis (48A) and the second lens axis (48B) are spaced apart a first lens separation distance (46a) that is different from the first emitter separation distance (42a).

Description

PCT APPLICATION of

Alexander Jason Whitmore for

LASER ASSEMBLY WITH OFFSET LENS ARRAY AND ANGULAR INSENSITIVE OUTPUT COUPLER

RELATED APPLICATION

[0001] This application claims priority on U.S. Provisional Application No.: 63/509,866, filed on June 23, 2023, and entitled “LASER ASSEMBLY WITH OFFSET LENS ARRAY AND ANGULAR INSENSITIVE OUTPUT COUPLER”. As far as permitted, the contents of U.S. Provisional Application No.: 63/509,866 are incorporated herein by reference.

BACKGROUND

[0002] Laser assemblies can be used in many fields such as, Lidar, medical diagnostics, pollution monitoring, leak detection, analytical instruments, homeland security, remote chemical sensing, industrial process control, and jamming of heatseeking missiles. Manufacturers are always searching for ways to reduce cost, reduce form factor, improve efficiency, improve beam quality, and improve power output of these laser assemblies.

SUMMARY

[0003] One implementation is directed to a laser assembly that generates an assembly output beam. The laser assembly can include: (i) an emitter array having a first emitter that generates a first emitter beam along a first emitter axis, and a second emitter that generates a second emitter beam along a second emitter axis, wherein the first emitter axis and the second emitter axis are spaced apart a first emitter separation distance; and (ii) a lens array including a first lens that colliminates the first emitter beam, and a second lens that colliminates the second emitter beam, wherein the first lens has a first lens axis and the second lens has a second lens axis, and wherein the first lens axis and the second lens axis are spaced apart a first lens separation distance that is different from the first emitter separation distance. [0004] With this configuration, in certain implemenations, the emitter array and the lens array can be designed and positioned so that the individual emitter beams are directed to spatially overlap onto a focal plane without any intermediary optical components. This minimizes the number of components in the laser assembly and reduces the number of components that need to be accurately manufacuted, accurately assemblied, and accurately maintained in alignment. As a result thereof, the laser assembly can be made less expensively, with a smaller form factor, and with improved quality of the assembly output beam. Moreover, with this design, it is relatively easy to maintain beam alignment and steering. Further, with this design, the output of multiple emitters can be easily combined to increase the power output of the laser assembly.

[0005] Additionally, the emitter array can include a third emitter that generates a third emitter beam along a third emitter axis and the lens array can include a third lens that colliminates the third laser beam. The third emitter axis and the second emitter axis are spaced apart a second emitter separation distance, and the third lens axis and the second lens axis are spaced apart a second lens separation distance that is different from the second emitter separation distance.

[0006] The first laser beam can be in a first spectral range and the second laser beam can be in a second spectral range that is different from the first spectral range.

[0007] The first lens directs the collimated first emitter beam at a first beam angle relative to the first emitter axis; and the second lens directs the collimated second emitter beam at a second beam angle relative to the second emitter axis. As provided herein, at least one of the beam angles has an absolute value that is not zero. For example, each of the beam angles can have an absolute value that is not zero.

[0008] In one implementation, the first lens axis is spaced apart a first offset from the first emitter axis, and/or the second lens axis is spaced apart a second offset from the second emitter axis. One or both offsets can be at least 0.001 millimeters.

[0009] In one implementation, the first lens separation distance is at least one percent different than the first emitter separation distance.

[0010] Additionally, in a non-excluisve implementation, the laser assembly can include a beam combiner that combines the collimated first emitter beam and the collimated second emitter beam into a combination beam. The beam combiner can includes a combiner surface having a normal. Further, the first lens can direct the collimated first emitter beam at a first angle of incidence relative to normal on the beam combiner; and the second lens can direct the collimated second emitter beam at a second angle of incidence relative to normal on the beam combiner. In this design, the second angle of incidence is different from the first angle of incidence.

[0011] In another implementation, the laser assembly can include an output coupler (i) that receives the combination beam from the beam combiner, (ii) that transmits a portion of the combination beam to provide the assembly output beam, and (iii) that redirects a portion of the combination beam back at the beam combiner. In certain designs, the output coupler is optomechanically insensitive to the position of the output coupler relative to the combination beam along at least one axis. Stated alternatively, in certain designs, the output coupler is uniquely designed so that its optical performance is insensitive to angular rotations of the output coupler relative to the combination beam along at least one axis.

[0012] In still another alternative implementation, a laser assembly that generates an assembly output beam can include an emitter array and a lens array. The emitter array can include (i) a first emitter that generates a first emitter beam, the first emitter having a first emitter axis, and (ii) a second emitterthat generates a second emitter beam, the second emitter having a second emitter axis. The lens array can include (i) a first lens that colliminates the first emitter beam and directs the collimated first emitter beam at a first beam angle relative to the first emitter axis; and (ii) a second lens that colliminates the second emitter beam and directs the collimated second emitter beam at a second beam angle relative to the second emitter axis. In this design, at least one of the beam angles has an absolute value that is not zero.

[0013] Additionally, the laser assembly can include a beam combiner that combines the collimated first emitter beam and the collimated second emitter beam into a combination beam. The first lens can direct the collimated first emitter beam at a first angle of incidence relative to normal on the beam combiner; and the second lens can direct the collimated second emitter beam at a second angle of incidence relative to normal on the beam combiner. The second angle of incidence can be different from the first angle of incidence.

[0014] Moreover, the laser assembly can include an output coupler that is optomechanically insensitive to the position of the output coupler relative to the combination beam along at least one axis. [0015] In still another implementation, the laser assembly can include (i) a laser array including a first emitter that generates a first emitter beam along a first emitter axis, (ii) a second emitter that generates a second emitter beam along a second emitter axis; (iii) a first lens that colliminates the first emitter beam; and (iv) a second lens that colliminates the second emitter beam. In this implementation, the first lens has a first lens axis and the second lens has a second lens axis; and the first lens axis is spaced apart a first offset from the first emitter axis. Further, the second lens axis can be spaced apart a second offset from the second emitter axis.

[0016] In yet another implementation, the laser assembly can again include an emitter array and a lens array. In this design, the emitter array includes a plurality of emitters that are spaced apart to have an emitter pitch, and the emitters cooperate to emit a plurality of emitter beams when power is directed to the emitter array. Further, the lens array collimates the plurality of emitter beams, and the lens array can include a plurality of lenses that are spaced apart to have a lens pitch that is different from the emitter pitch.

[0017] In another implementation, the laser assembly includes a laser array and an output coupler. The laser array generates a combination beam; and the output coupler acts as an output coupler for the laser array; the output coupler receiving the combination beam, redirecting at least a portion of the combination beam back to the laser array, and transmitting a portion of the combination beam as the assembly output beam. In this design, the output coupler is optomechanically insensitive to the position of the output coupler relative to the combination beam about at least two axes.

[0018] Additionally, the output coupler can be optomechanically insensitive to the position of the output coupler relative to the combination beam about three axes.

[0019] In one non-exclusive design, the output coupler includes a first optical element, a partly reflective element and a second optical element that are positioned along a coupler axis. In this design, the first focusing element can be an axisymmetric focusing element that focuses the combination beam at an area on the partly reflective element. Alternatively, the first focusing element can focuses the combination beam along one axis on the partly reflective element.

[0020] In a different design, the output coupler includes a partly reflective prism that receives the combination beam, redirects at least a portion of the combination beam back to the laser array, and transmits a portion of the combination beam as the assembly output beam. [0021] In this design, the partly reflective prism directs a transverse portion of the combination beam traverse to the coupler axis, and wherein the output coupler includes a beam redirector that redirects the transverse portion back to the partly reflective prism.

[0022] In another implementation, the laser assembly includes an emitter array including a first emitter and a second emitter, and an lens array including a first lens and a second array. In this implementation, the laser assembly including one or more of the following: (i) a first lens separation distance that is different from a first emitter separation distance; (ii) the first lens directs the collimated first emitter beam at a first beam angle, the second lens directs the collimated second emitter beam at a second beam angle, and at least one of the beam angles has an absolute value that is not zero; (iii) the first lens axis is substantially parallel to and spaced apart a first offset from the first emitter axis; and/or (iv) a lens pitch that is different from an emitter pitch.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:

[0024] Figure 1A is a simplified illustration of an embodiment of a laser assembly;

[0025] Figure 1 B is a simplified illustration of a portion of the laser assembly of Figure 1A;

[0026] Figure 1 C is a simplified schematic illustrating features of the present invention;

[0027] Figure 1 D is a simplified illustration of a first set of different center wavenumbers versus power generated by the laser assembly of Figure 1 A;

[0028] Figure 1 E is a simplified illustration of the first set of different center wavenumbers versus angle of incidence on a beam combiner;

[0029] Figure 2A is a simplified illustration of another embodiment of a laser assembly;

[0030] Figure 2B is a graph that illustrates the far field intensity of an assembly output beam along an X axis; [0031] Figure 2C is a graph that illustrates the far field intensity of an assembly output beam along a Y axis;

[0032] Figure 3 is a simplified illustration of still another embodiment of a laser assembly;

[0033] Figure 4 is a simplified illustration of yet another embodiment of a laser assembly;

[0034] Figure 5A is a simplified illustration of a non-exclusive implementation of an output coupler;

[0035] Figure 5B is a simplified illustration of a portion of the output coupler of Figure 5A;

[0036] Figure 6A is a simplified illustration of another, non-exclusive implementation of an output coupler;

[0037] Figure 6B is a simplified illustration of a portion of the output coupler of Figure 6A;

[0038] Figure 7A is a simplified illustration of still another, non-exclusive implementation of an output coupler;

[0039] Figure 7B is a simplified illustration of a portion of the output coupler of Figure 7A; and

[0040] Figure 8 is a simplified illustration of yet another, non-exclusive implementation of an output coupler.

DESCRIPTION

[0041] Figure 1A is simplified top illustration of a first embodiment of a laser assembly 10 that generates an assembly output beam 12 (illustrated with an arrow). In certain embodiments, the laser assembly 10 includes (i) a laser frame 14, (ii) a laser subassembly 16 that includes an emitter array 17 having a plurality of emitters 18 that cooperate to generate a plurality of emitter (“laser”) beams 20 (illustrated as arrows), and a lens array 21 having a plurality of lenses 22, (iii) a beam combiner 24 that transforms and combines the plurality of emitter beams 20 into the assembly output beam 12, (iv) an output coupler 26, and (v) a system controller 28 that controls the operation of the laser subassembly 16. In this embodiment, each of the emitter beams 20 can be coherent. Additionally, the laser assembly 10 can include a power supply 30 (e.g. a battery, the electrical grid, or a generator) that provides electrical power to the system controller 28. Further, the laser assembly 10 can be secured to a rigid mount 32 such as a test or experimental bench, a frame of a vehicle or aircraft, or other rigid structure. Moreover, the rigid mount 32 can be thermally isolated. The design of each of the components of the laser assembly 10 can be varied to vary the characteristics of the assembly output beam 12.

[0042] In certain embodiments, the plurality of emitters 18 are organized in an emitter array 34, and the plurality of lenses 22 are organized in a lens array 21 . As an overview, the lens array 21 can be offset from the emitter array 34. Stated in another fashion, (i) the emitters 18 of the emitter array 34 are arranged to have an emitter pitch, (ii) the lenses 22 of the lens array 21 are arranged to have a lens pitch, and (ii) the lens pitch is different from the emitter pitch. With this configuration, in certain implemenations, the emitter array 34 and the lens array 21 can be designed and positioned so that the individual laser beams 20 are directed to spatially overlap onto a combiner focal plane 24A of the beam combiner 24 without any intermediary optical components. This minimizes the number of components in the laser assembly 10 and reduces the number of components that need to be accurately made and maintained in alignment. As a result thereof, the laser assembly 10 can be made less expensively, with a smaller form factor, and with improved quality of the assembly output beam 12. Further, with this design, the output of multiple emitters 18 can be easily combined to increase the power output of the laser assembly 10.

[0043] Additionally or alternatively, in certain embodiments, the output coupler 26 can be uniquely designed to be optomechanically, angularly insensitive to the position of the output coupler 26 relative to the multispectral beams about at least two axes. This reduces the requirement to obtain and maintain the alignment of the output coupler 26, the emitter array 34, the lens array 21 , and/or the beam combiner 24. For example, the beam combiner 24 can be a diffraction grating that allows the laser assembly 10 to be angularaly insensitivity. As a result thereof, the laser assembly 10 can to be made less expensively, with improved quality of the assembly output beam 12, and improved stability and power of the assembly output beam 12.

[0044] In certain present designs, the laser assembly 10 is a compact, high efficiency, high output, external cavity laser assembly 10 that spectrally combines the emitter beams 20 of multiple individual emitters 18 into a single spatial, multi-spectral, assembly output beam 12 that is diffraction-limited or near diffraction-limited. In the implementation of Figure 1 A, the laser assembly 10 is an external cavity laser, and the beam combiner 24 is a diffraction grating that transforms and combines the collimated emitter beams into a multi-specral combination beam that is directed along the output axis 12A.

[0045] In this design, the beams from the emitters 18 (via the corresponding lenses 22) are directed to overlap on the diffraction grating 24 (wavelength angular dispersive element) and the diffraction grating 24 directs the beams to be substantially parallel and overlapping. However, each of the beams is incident on the diffraction grating 24 at a different angle, and the beams will have a different center wavenumber.

[0046] With this design, multiple emitters 18, each generating a separate emitter beam 20 having relatively moderate output power, can be combined into a multi-Watt module configuration that offers many practical benefits. For example, a lower per-facet intensity of each emitter 18 translates into lower thermal stress on the individual emitters 18, providing more long term system reliability. In addition, emitters 18 with lower power requirements can be manufactured with much higher yields, providing a dependable supply at lower costs. Further, the combined beams provide more power while preserving good spatial quality.

[0047] Moreover, the optical power of the assembly output beam 12 can be changed by changing the number of emitters 18 used in the laser subassembly 14. Thus, the design of laser assembly 10 can be easily adjusted to add or remove emitters 18 based on the desired output power of the assembly output beam 12. As a non-exclusive example, the laser assembly 10 can be designed so that the assembly output beam 12 has an optical power of between five to fifty watts. Stated in another fashion, in alternative, non-exclusive embodiments, the laser assembly 10 can be designed so that the assembly output beam 12 has an optical power of at least five, ten, fifteen, twenty, twenty-five, thirty, thirty-five, forty, forty-five, fifty, sixty, eighty, or one hundred watts. However, optical powers of less than five, or greater than one hundred watts are possible.

[0048] As provided herein, the resulting assembly output beam 12 is made up of the plurality of individual emitter beams 20 that are collimated and directed by the beam combiner 22 to co-propagate, and be coaxial with each other along an output axis 12A. As used herein, the term “combines” as used in regards to the assembly output beam 12 shall mean (i) that the beams are directed substantially parallel to one another (i.e, the beams travel along substantially parallel axes), and/or (ii) that the beams are fully or partly spatially overlapping. [0049] Further, in certain designs, the assembly output beam 12 will be multispectral because each of the individual emitters 18 is lasing at a different center wavenumber as a result of the arrangement of the laser assembly 10. In certain embodiments, the laser assembly 10 is designed so that the assembly output beam 12 has a relatively small spectral width. In alternative, non-exclusive embodiments, the laser assembly 10 is designed so that the assembly output beam 12 has a spectral width of less than 0.025, 0.05, 0.1 , 0.2, 0.3, 0.5, 0.75, 1 , or 1 .5 microns. For example, a ten emitter 18 design could achieve a spectral width of less than 0.1 microns, while a twenty emitter 18 design could achieve a spectral width of less than 0.2 microns.

[0050] The designs described herein provide the following benefits: (i) getting more power into the output beam 12 while preserving good spatial quality; (ii) getting high power out of the laser assembly 10 with a relatively small footprint; and/or (iii) providing different frequency pulses of light that travel down the same output axis 12A (at the same time or at different times depending on how the emitters 18 are controlled).

[0051] A number of Figures include an orientation system that illustrates an X axis, a Y axis that is orthogonal to the X axis and a Z axis that is orthogonal to the X and Y axes. It should be noted that these axes can also be referred to as the first, second and third axes.

[0052] The laser frame 14 is rigid, thermally stable, supports the other components of the laser assembly 10, and maintains the precise alignment of the components of the laser assembly 10. In Figure 1 , for simplicity, the laser frame 14 is illustrated as a flat plate. However, for example, the laser frame 14 can be a sealed or unsealed housing that encircles and provides a controlled environment for the other components of the laser assembly 10. If the laser frame 14 is a housing, the laser frame 14 can include a window (not shown) for the assembly output beam 12 to exit the laser frame 14. Further, if the laser frame 14 is sealed, it can be filled with an inert gas, or another type of fluid, or the sealed chamber can be subjected to a vacuum. Still alternatively, for example, desiccant or another drying agent can be positioned in the laser frame 14 to trap gases that could absorb laser emissions, cause corrosion, and/or to cause condensation.

[0053] In one, non-exclusive embodiment, the laser subassembly 16 includes a common laser mount 38, the plurality of emitters 18, and the plurality of lenses 22. [0054] The laser mount 38 retains and secures the emitters 18 and the lenses 22 to the laser frame 14. In one embodiment, the laser mount 38 includes a mounting base 38A and a thermally conductive sub-mount 38B. In one non-exclusive embodiment, the mounting base 38A is rigid, generally rectangular shaped, and includes a plurality of embedded base passageways 38C, e.g. micro-channels (only a portion is illustrated in phantom) that allow for the circulation of a circulation fluid (not shown) through the mounting base 38A. Non-exclusive examples of suitable materials for the mounting base 38A include copper, Glidcop, Molybdenum-Copper (MoCu), molybdenum, copper tungsten (CuW), aluminum, and aluminum nitride (ALN).

[0055] The sub-mount 38B retains the multiple emitters 18 and secures the emitters 18 to the mounting base 38A. Additionally, in certain designs, the sub-mount 38B can electrically isolate the emitters 18 from the mounting base 38A. In one embodiment, the sub-mount 38B is rectangular plate shaped and is made of rigid material that has a relatively high thermal conductivity to act as a conductive heat spreader. In one non-exclusive embodiment, the sub-mount 38B has a thermal conductivity of at least approximately 170 watts/meter K. With this design, in addition to rigidly supporting the emitters 18, the sub-mount 38B also readily transfers heat away from the emitters 18 to the mounting base 38A. For example, the sub-mount 38B can be fabricated from a single, integral piece of copper, copper-tungsten (CuW), copper-moly, molybdenium, aluminum-nitride (AIN), beryllium oxide (BeO), diamond, silicon carbide (SiC), or other material having a sufficiently high thermal conductivity.

[0056] In certain embodiments, the material used for the sub-mount 38B can be selected so that its coefficient of thermal expansion matches the coefficient of thermal expansion of the emitters 18.

[0057] Additionally, the laser assembly 10 can include a thermal controller 40 (illustrated as a box) that controls the temperature of the mounting base 38A and/or the emitters 18. For example, the thermal controller 40 can include (i) one or more pumps (not shown), chillers (not shown), heaters (not shown), and/or reservoirs that cooperate to circulate a hot or cold circulation fluid (not shown) through the base passageways 38C to control the temperature of the mounting base 38A, and (ii) a temperature sensor 40A (e.g., a thermistor) that provides feedback for closed loop control of the temperature of the mounting base 38A and/or the emitters 18. With this design, the thermal controller 40 can be used to directly control the temperature of the mounting base 38A at a predetermined temperature. [0058] With this design, the thermal controller 40 can be used to maintain nearconstant temperature of the laser assembly 10 for purposes of maintaining optical alignment over (i) a range of environmental temperatures; (ii) a range of heat loads produced when powering the emitters 18; and/or (iii) a range of heat loads generated within the optical elements due to absorption, scattering, and stray light.

[0059] In the non-exclusive embodiment illustrated in Figure 1A, the thermal controller 40 is positioned outside the laser frame 14 and the temperature sensor 40A is positioned on the mounting base 38A. Alternatively, the thermal controller 40 can be in direct thermal contact with the mounting base 38A and/or positioned on or in the laser frame 14. Additionally, or alternatively, the thermal controller 40 can also include one or more cooling fans and/or vents to further remove the heat generated by the operation of the laser assembly 10. Further, the temperature sensor 40A can be placed in the coolant path, though other positions will also work.

[0060] The number, size, shape and design of the emitters 18 can be varied to achieve the desired characteristics of the assembly output beam 12. For example, the emitter array 17 can include between two and five hundred emitters 18 that are arranged in the array. In Figure 1A, for ease of illustration, the emitter array 17 includes six separate, spaced apart emitters 18. As alternative, non-exclusive examples, the laser assembly 16 can include at least 4, 5, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 50, 100, 150, 200, 250, 300, 400, or 500 separate emitters 18 that are arranged in the emitter array 17. In certain designs, the emitter array 17 can be accurately manufactured using lithography or other techniques.

[0061] Additionally, in alternative, non-exclusive embodiments, each emitter 18 can be designed and powered to generate at least approximately 0.5W, 1 W, 1.5W, 2W, 2.5W, 3W, 3.5W, 4W, 4.5W, 5W, 5.5W, 6W, 6.5W, 7W, 7.5W, 8W, 8.5W, 9W, 9.5W, 10W, 10.5W, 11W, 11.5W, 12W, 12.5W, 13W, 13.5W, 14W, 14.5W, 15W,

15.5W, 16W, 16.5W, 17W, 17.5W, 18W, 18.5W, 19W, 19.5W, 20W, 20.5W, 21W,

21 ,5W, 22W, 22.5W, 23W, 23.5W, 24W, 24.5W, 25W, 25.5W, 26W, 26.5W, 27W,

27.5W, 28W, 28.5W, 29W, 29.5W, or 30W of output power. However, other output powers are possible, such as less than 0.5W or greater than 30W.

[0062] As non-exclusive examples, each of the emitters 18 can be a Quantum Cascade (“QC”) gain medium, a laser diode (e.g. Gallium Antimony), or an interband cascade laser. Each emitter 18 can alternatively be referred to as a gain medium. Further, in one, non-exclusive embodiment, each emitter 18 is an infrared laser source that directly generates the emitter beam 20 having a center wavelength that is in the mid to far infrared wavelength range of three to thirty microns. In another nonexclusive embodiment, each emitter 18 is a mid-infrared laser source that directly generates the emitter beam 20 having a center wavelength that is in the mid-infrared wavelength range of two to twenty microns.

[0063] The density and spacing of the emitters 18 can be selected based on the ability to remove the heat with the thermal controller 40.

[0064] In certain embodiments, the emitters 18 can be bonded/mounted episide down to the sub-mount 38B to allow for (i) individually addressability of emitters 18; (ii) high duty factor optimization; (iii) high capacity liquid cooling of the emitters via the mounting base 38A; and/or (iv) maximum optical power while minimizing core/gain layer and facet optical temperature. For example, if each emitter 18 is a QC gain medium, each emitter 18 can be hard-soldered or soft-soldered to the sub-mount 38B directly with thin, highly-conductive solder such as Indium, orAuSn. Moreover, in this implementation, the emitter array 17 can be accurately manufactured using lithography or another process.

[0065] If the emitters 18 are individually addressable, (i) the laser assembly 10 will still be operational in the event of failure of one emitter 18 or a subset of the emitters 18; and (ii) the emitters 18 can be powered on or off individually by the system controller 28. Alternatively, the emitters 18 can be electrically connected such that all of the emitters 18 are powered on or off concurrently. In contrast, if each individual emitter 18 is sequentially powered, the center wavelength (wavenumber) of the assembly output beam 12 will change as each individual emitter 18 is powered because each emitter 18 will lase at a different center wavenumber as detailed below. This allows for discretized form of spectroscopy whereby light of distinct wavenumbers can be generated independently by the distinct emitters 18 and directed at an analyte (not shown). Spectral signatures of the analyte (e.g., absorption, reflection, birefringence, etc) may be correlated to the distinct wavenumbers via e.g., timedivision multiplexing i.e. , encoding the emission time of each individual emitter to the detector signal. Many other schemes of encoding are possible and well known to those skilled in the art of spectroscopy. Further, the emitters 18 may be turned on and off in subsets rather than individually to exploit possible further improvements in signal detection efficiency. [0066] Figure 1 B is an enlarged view of the plurality of emitters 18, and the plurality of lens 22 of Figure 1A. In this non-exclusive implementation, (i) the emitters 18 are aligned and spaced apart along a one-dimensional emitter array axis 17a (along the X axis), (ii) the emitters 18 are centered on an emitter array central axis 17b, and (iii) each emitter 18 generates a separate emitter beam 20. In the non-exclusive implementation of Figure 1 B, each emitter beam 20 is diverging as it exits the respective emitter 18.

[0067] As provided herein, the emitters 18 of the emitter array 17 are arranged to have an emitter pitch, which represents the distance between adjacent emitters 18 which is repeated in the emitter array 17. Stated differently, the emitters 18 of the emitter array 17 are arranged to have an emitter spacing 42 (also referred to as an “emitter separation distance”) between adjacent emitters 18. In implementation of Figure 1 B, the emitters 18 are aligned along the one dimensional, emitter array axis 17a (e.g., along the X axis). Further, the emitter spacing 42 can be varied based on the ability to remove the heat with the thermal controller 40 (illustrated in Figure 1A). As alternative, non-exclusive examples, the emitter spacing 42 can be less than approximately 0.1 , 0.2, 0.3, 0.4, 0.5, 0.75, 1 , 1.5, 2, 2.5, or 3 millimeters. Stated in another fashion, the emitter spacing 42 can be between approximately 0.1 and 3 millimeters.

[0068] In one non-exclusive implementation, the emitter array 17 is designed so that the emitters 18 are equally spaced (e.g., along the emitter array axis 17a) and the emitter array 17 is uniform. In this design, the emitter array 17 can be referred to as having a uniform spacing or uniform emitter pitch. Alternatively, the emitter spacing 42 between the emitter axis of adjacent pairs of emitters 18 (e.g., aligned along the one dimensional, emitter array axis 17a) can be a non-uniform distribution. In this design, the emitter array 17 can be referred to as having a non-uniform spacing or non-uniform emitter pitch.

[0069] For ease of discussion, moving top to bottom, the emitters 18 can be labeled (i) a first emitter 18A that is centered on a first emitter axis 44A, and that emits a first emitter beam 20A along and coaxial with the first emitter axis 44A; (ii) a second emitter 18B that is centered on a second emitter axis 44B, and that emits a second emitter beam 20B along and coaxial with the second emitter axis 44B; (iii) a third emitter 18C that is centered on a third emitter axis 44C, and that emits a third emitter beam 20C along and coaxial with the third emitter axis 44C; (iv) a fourth emitter 18D that is centered on a fourth emitter axis 44D, and that emits a fourth emitter beam 20D along and coaxial with the fourth emitter axis 44D; (v) a fifth emitter 18E that is centered on a fifth emitter axis 44E, and that emits a fifth emitter beam 20E along and coaxial with the fifth emitter axis 44E; and (vi) a sixth emitter 18F that is centered on a sixth emitter axis 44F, and that emits a sixth emitter beam 20F along and coaxial with the sixth emitter axis 44F. In the non-exclusive implementation of Figure 1 B, the emitter axes 44A-44F are substantially parallel to each other. The term emitter pitch refers to the emitter spacing referenced to the emitter axes.

[0070] It should be noted that any of the emitters 18 can be referred to as the first, second, third, etc emitter 18. Somewhat similarly, any of the emitter beams 20 can be referred to as a first, second, third, etc. emitter beam 20, or as a first, second, third, etc. laser beam 20.

[0071] In Figure 1 B, (i) the first emitter axis 44A and the second emitter axis 44B are spaced apart a first emitter separation distance 42a along the emitter array axis 17a; (ii) the second emitter axis 44B and the third emitter axis 44C are spaced apart a second emitter separation distance 42b along the emitter array axis 17a; (iii) the third emitter axis 44C and the fourth emitter axis 44D are spaced apart a third emitter separation distance 42c along the emitter array axis 17a; (iv) the fourth emitter axis 44D and the first emitter axis 44E are spaced apart a fourth emitter separation distance 42d along the emitter array axis 17a; and (v) the fifth emitter axis 44E and the sixth emitter axis 44F are spaced apart a fifth emitter separation distance 42e along the emitter array axis 17a.

[0072] In the non-exclusive design of Figure 1A, the emitter array 17 is a onedimensional array with the emitters 18 being spaced apart along only the emitter array axis 17a. Alternatively, the emitter array 17 can be a two dimensional array with the emitters 18 being spaced apart along the emitter array axis 17a, and along the Y axis.

[0073] In one, non-exclusive embodiment, each emitter separation distance 42 can be less than approximately 0.05, 0.1 , 0.2, 0.3, 0.4, 0.5, 0.75, 1 , 1.5, 2, 2.5, or 3 millimeters. Stated differently, each emitter separation distance 42 can be between 0.05 and 3 millimeters. Further each emitter separation distance 42 can be the same or slightly different. In the non-exclusive implementation of Figure 1 B, the emitters 18 are equally spaced apart. As a result thereof, the emitter separation distances 42a- 42e are all equal. However, in the implementation with a non-uniform distribution, one or more of the emitter separation distances 42a-42e is different from one or more of the other emitter separation distances 42a-42e. As a non-exclusive example, the first emitter separation distance 42a can be different than one or more of the other separation distances 42b-42e.

[0074] In one embodiment, each emitter 18 has a back facet 18G and an opposed front facet 18H that faces the lens array 21 , and each emitter 18 is designed to only emit from the front facet 18H. In this embodiment, the back facet 18G is coated with a high reflectivity dielectric or metal/dielectric coating to minimize optical losses from the back facet 18G and to allow the back facet 18G of each emitter 18 to function a first laser cavity end of a cavity for each emitter 18. Further, the front facet 18H can include an anti-reflective dielectric coating to minimize coupled cavity effects within the laser assembly 10. For example, the coating on the front facet 18H can be optimized to minimize reflectivity across the available gain-bandwidth of the emitters 18. In one non-exclusive embodiment, the anti-reflective coating can have a reflectivity of less than approximately two percent, and the highly reflective coating can have a reflectivity of greater than ninety percent.

[0075] In certain implementations, each of the emitter beams 20 emitted from the emitters 18 is diverging and not-collimated. The lens array 21 individually collimates the laser beams 20 emitted from the emitters 18. In certain embodiments, (i) the lens array 21 includes a separate micro-lens 22 for each emitter 18, (ii) the lenses 22 are aligned and spaced apart (e.g., along a one-dimensional lens array axis 21 a), and (iii) the lens array 21 has a lens array central axis 21 b. In Figure 1 B, the lens array central axis 21 b is coaxial with the emitter array central axis 17b. Alternatively, the lens array central axis 21 b can be offset from the emitter array central axis 17b.

[0076] In Figure 1 B, the lenses 22 of the lens array 21 are slightly spaced apart (and adjacent to each other) along the lens array axis 21 a. Alternatively, the lens array 21 can be designed so that adjacent micro-lenses are in contact with each other (no spacing therebetween). As provided herein, the lenses 22 of the lens array 21 are spaced and arranged to have a lens pitch (referenced to the lens axes), which represents the distance between adjacent lenses 22 which is repeated in the lens array 21. Further, the lens pitch is different from the emitter pitch. Stated in a different fashion, the lens array 21 has a lens spacing (“lens separation distance”) 46 which is different from the emitter spacing (“emitter separation distance”) 42. [0077] For ease of discussion, moving top to bottom, the lenses 22 of the lens array 21 can labeled (i) a first lens 22A that has a first lens axis 48A, and that collimates the first laser beam 20A to provide a collimated first laser beam 50A directed at the beam combiner 24 (illustrated in Figure 1A); (ii) a second lens 22B that has a second lens axis 48B, and that collimates the second laser beam 20B to provide a collimated second laser beam 50B directed at the beam combiner 24; (iii) a third lens 22C that has a third lens axis 48C, and that collimates the third laser beam 20C to provide a collimated third laser beam 50C directed at the beam combiner 24; (iv) a fourth lens 22D that has a fourth lens axis 48D and that collimates the fourth laser beam 20D to provide a collimated fourth laser beam 50D directed at the beam combiner 24; (v) a fifth lens 22E that has a fifth lens axis 48E, and that collimates the fifth laser beam 20E to provide a collimated fifth laser beam 50E directed at the beam combiner 24; and (vi) a sixth lens 22F that has a sixth lens axis 48F, and that collimates the sixth laser beam 20F to provide a collimated sixth laser beam 50F directed at the beam combiner 24. Any of the lenses 22 can be referred to as the first, second, third, etc lens. In the non-exclusive implementation of Figure 1 B, the lens axes 48A-48F are parallel to each other.

[0078] In the non-exclusive design of Figure 1A, the lens array 21 is a onedimensional array with the lenses 22 being spaced apart along only the lens array axis 21 a. Alternatively, the lens array 21 can be a two array with the lenses 22 being spaced apart along the lens array axis 21 a, and along the Y axis.

[0079] As provided above, in certain embodiments, (i) one or more (e.g., a plurality) of lenses 22 of the lens array 21 is offset from its corresponding emitter 18 of the emitter array 17 or another axis; and/or (ii) the lens array 21 has a lens spacing 46 which is different from the emitter spacing 42. Stated in a different fashion, each lens axis 48A-48F is not coaxial (and is off center) with the emitter axis 44A-44F of its corresponding emitter 18. In this design, the angular boresight of each collimated beam 50A-50F is pointing at an angle relative to the corresponding emitter axis 44A- 44F. In Figure 1 B, as provided herein, in certain implementations, the emitters 18 are spaced apart along the emitter array axis 17a, the lenses 22 are spaced apart along the lens array axis 21a, and the lens array axis 21 a is substantially parallel to the emitter array axis 17a and the X axis.

[0080] Further, as provided herein, in Figure 1 B, (i) the first lens axis 48A is parallel to and spaced apart a first offset 52a from the first emitter axis 44A along an axis (e.g., the X axis); (ii) the second lens axis 48B is parallel to and spaced apart a second offset 52b from the second emitter axis 44B along an axis (e.g., the X axis); (iii) the third lens axis 48C is parallel to and spaced apart a third offset 52c from the third emitter axis 44C along an axis (e.g., the X axis); (iv) the fourth lens axis 48D is parallel to and spaced apart a fourth offset 52d from the fourth emitter axis 44D along an axis (e.g., the X axis); (v) the fifth lens axis 48E is parallel to and spaced apart a fifith offset 52d from the fifth emitter axis 44E along an axis (e.g., the X axis); and (vi) the sixth lens axis 48F is parallel to and spaced apart a sixth offset 52f from the sixth emitter axis 44F along an axis (e.g., the X axis).

[0081] Alternatively, depending on the design of the laser assembly 10, one or more of the lens axes can be coaxial with its corresponding emitter axis. For example, for an emitter 18 located in a center of the emitter array, its corresponding lens 22 can be aligned and coaxial. In a specific example, for an emitter array with seven emitters (not shown in Figure 1 B), (i) the fourth emitter can be centrally located and positioned on a fourth emitter axis; and (ii) its corresponding lens, e.g., the fourth lens can be positioned on a fourth lens axis that can be coaxial with the fourth emitter axis. With this design, the fourth emitter beam will be coaxial with the fourth emitter axis and the fourth lens axis.

[0082] The magnitude of each offset 52a-52f can be varied to suit the design requirements of the laser assembly 10. As provided herein, the offsets 52a-52f can be selected so that the collimated laser beams 50A-50F are directed to spatially overlap onto the combiner focal plane 24a (illustrated in Figure 1A). As alternative, non-exclusive examples, the magnitude of one or more of the offsets 52a-52f is at least 0.001 , 0.001 , 0.01 , 0.1 , 0.2, 0.3, 0.5, 1 , or 2 millimeters.

[0083] Further, each offset 52a-52f can be the same or different in magnitude. In the non-exclusive implementation of Figure 1 B, (i) the first offset 52a is equal to the sixth offset 52f; (ii) the second offset 52b is equal to the fifth offset 52e; (iii) the third offset 52c is equal to the fourth offset 52d; (iv) the first and sixth offsets 52a, 52f are greater than the second and fifth offsets 52b, 52e; and (v) the second and fifth offsets 52b, 52e are greater than the third and fourth offsets 52c, 52d.

[0084] Described in a different fashion, in the non-exclusive implementiaton of Figure 1 B, (i) the first lens axis 48A is substantially parallel to and spaced apart a first lens separation distance 46a from the second lens axis 48B; (ii) the second lens axis 48B is substantially parallel to and spaced apart a second lens separation distance 46b from the third lens axis 48C; (iii) the third lens axis 48C is substantially parallel to and spaced apart a third lens separation distance 46c from the fourth lens axis 48D; (iv) the fourth lens axis 48D is substantially parallel to and spaced apart a fourth separation distance 46d from the fifth lens axis 48E; and (v) the fifth lens axis 48E is substantially parallel to and spaced apart a fifth separation distance 46e from the sixth lens axis 48F. In one, non-exclusive embodiment, each lens separation distance 46a- 46e can be less than approximately 0.1 , 0.2, 0.3, 0.4, 0.5, 0.75, 1 , 1.5, 2, 2.5, or 3 millimeters. Stated differently, each lens separation distance 46a-46e can be between 0.05 and 3 millimeters.

[0085] Further, one or more of the beam separation distances 46a-46e can be the same or slightly different. In Figure 1 B, the lens array 21 has a non-uniform distribution, and one or more of the lens separation distances 46a-46e is different from the other lens separation distances 46a-46e. As a non-exclusive example, the first lens separation distance 46a can be different than one or more of the other lens separation distances 46b-46e.

[0086] In the non-exclusive implementation of Figure 1 B, the emitters 18 are equally spaced apart and lenses 22 are non-uniform ly spaced apart. Alternatively, the laser assembly 10 could be designed with the lens 22 being uniformly spaced apart, and the emitters 18 being non-uniformly spaced apart. Still alternatively, both the lenses 22 and emitters 18 can being non-uniformly spaced apart.

[0087] In the non-exclusive implementation of Figure 1 B, (i) the first lens separation distance 46a is different from (and not equal to) the first emitter separation distance 42a; (ii) the second lens separation distance 46b is different from (and not equal to) the second emitter separation distance 42b; (iii) the third lens separation distance 46c is different from (and not equal to) the third emitter separation distance 42c; (iv) the fourth lens separation distance 46d is different from (and not equal to) the fourth emitter separation distance 42d; (v) the fifth lens separation distance 46e is different from (and not equal to) the fifth emitter separation distance 42e; and (vi) the sixth lens separation distance 46f is different from (and not equal to) the fifth emitter separation distance 42f.

[0088] The amount of difference between the lens separation distance 46 and its corresponding emitter separation distance 42 can be varied to achieve the desired configuration of the laser assembly 10. As alternative, non-exclusive examples, the one or more of the lens separation distances 46a-46e can be approximately 0.0001 , 0.001 , 0.01 , 0.1 , 0.2, 0.5, 1 , 1.5, or 3 millimeters different from (greater or less than) its corresponding emitter separation distance 42a-42e. For example, the first lens separation distances 46a can be approximately 0.0001 , 0.001 , 0.01 , 0.1 , 0.2, 0.5, 1 , 1.5, or 3 millimeters different from (greater or less than) the first emitter separation distance 42a. Stated in a different fashion, as alternative, non-exclusive examples, the one or more of the lens separation distances 46a-46e can be at least approximately 0.01 , 0.1 , 1 , 2, 3, 5, 7, 10, 33, or 50 percent different from (greater or less than) its corresponding emitter separation distance 42a-42e.

[0089] With this design, the emitter array 17 and the lens array 32 are designed and aligned to direct the colliminated emitter beams 50A-50F to spatially overlap onto the combiner focal plane 24a of beam combiner 24.

[0090] Moreover, with the present design in Figure 1 B, (i) the first lens 22A directs the colliminated first laser beam 50A at a first beam angle 54a relative to the first emitter axis 444A, and the first lens axis 48A; (ii) the second lens 22B directs the colliminated second laser beam 50B at a second beam angle 54b relative to the second emitter axis 44B, and the second lens axis 48B; (iii) the third lens 22C directs the colliminated third laser beam 50C at a third beam angle 54c relative to the third emitter axis 44C, and the third lens axis 48C; (iv) the fourth lens 22D directs the colliminated fourth laser beam 50D at a fourth beam angle 54d relative to the fourth emitter axis 44D, and the fourth lens axis 48D; (v) the fifth lens 22E directs the colliminated fifth laser beam 50E at a fifth beam angle 54e relative to the fifth emitter axis 44E, and the fifth lens axis 48E; and (vi) the sixth lens 22F directs the colliminated sixth laser beam 50F at a sixth beam angle 54f relative to the sixth emitter axis 44F, and the fifth lens axis 48F.

[0091] As provided herein, the one or more (e.g., all) of the beam angles 54a- 54f has an absolute value that is not equal to zero. As alternative, non-exclusive examples, the absolute value of one or more of the beam angles 54a-54f can be at least approximately 1 , 4, 5, 10, 25, 50, 100, 150, 250, or 500 milliradians.

[0092] Further, one or more of the beam angles 54a-54f can be the same or slightly different in magnitude. In Figure 1 B, each of the beam angles 54a-54f is different from the other beam angles 54a-54f. In the non-exclusive implementation of Figure 1 B, (i) the absolute value of the first beam angle 54a is equal to the absolute value of the sixth beam angle 54f; (ii) the absolute value of the second beam angle 54b is equal to the absolute value of the fifth beam angle 54e; (iii) the absolute value of the third beam angle 54c is equal to the absolute value of the fourth beam angle 54d; (iv) the absolute values of the first and beam angles 54a, 54f is greater than the absolute values of the second and fifth beam angles 54b, 54e; and (v) the absolute values of the second and fifth beam angles 54b, 54e are greater than the absolute values of the third and fourth beam angles 54c, 54d.

[0093] In one, non-exclusive embodiment, each lens 22A-22F is a spherical lens having an optical axis that is offset from its corresponding emitter axis 44A- 44F. In one, non-exclusive embodiment, each lens 22A-22F has a diameter of between approximately 50 microns and 3 millimeters. For example, each lens 22A-22F has a working distance and the lens 22A-22F is spaced apart from its respective emitter 18A-18F a separation distance that is less than or equal to the working distance. In one, non-exclusive embodiment, each lens 22A-22F is spaced apart from the respective emitter 18A-18F and has a working distance of between approximately 10 microns and 500 microns. Stated in another fashion, in alternative, non-exclusive implementations, the each lens 22A-22F is spaced apart from the respective emitter 18A-18F a distance less than 10, 20, 40, 50, 100, 200, 250, 300, 400, or 500 microns.

[0094] The lens array 21 creates diffraction limited or near diffraction limited collimated beams 20A-20F that are directed at the beam combiner 24. As nonexclusive examples, each of the lens 22A-22F can (i) be aspheric; (ii) be conic; (iii) be spherical; (iv) be Plano-Convex, Bi-convex, a Meniscus lens, or double sided; (v) be transparent in lasing optical bandwidth of the laser beams 20A-20F; (vi) be anti- reflective coated on both sides; (vii) be fabricated using greyscale lithographically fabrication; (viii) be micro-machined using diamond turning; (ix) be molded; (x) be made of a low distortion substrate; (xi) dissipate heat and prevent thermal runaway at high power; (xii) have low insertion loss; (xiii) be spaced to match or differ from the emitter spacing; and (xiv) include metallization to allow soldering to reduce outgassing materials and to provide conductive heat path.

[0095] In one embodiment, each of the lenses 22A-22F can have a high numerical aperture (e.g. 0.75 or greater) and can be designed to match the output from the respective emitter 18A-18F to maximize collection efficiency. Stated in another fashion, the type of material used for each lens 22A-22F can be varied to match the wavelengths of the laser beams 20A-20F. For example, for infrared emitters 18A-18F, each lens 22A-22F can comprise materials selected from the group of germanium, silicon, sapphire, or ZnSe. However, other materials may also be utilized that are effective with the wavelengths of the beams 22A-22F.

[0096] Moreover, in certain embodiments, the lens array 21 with all of the lenses 22 can be accurately manufactured using grayscale lithography etching or other procedures. This allows for a stable and accurately made lens array 21 that can be maintained in precise alignment with the emitter array 17. This improves the reliability of the laser assembly 10, and allows the laser assembly 10 to be made relatively inexpensively.

[0097] In certain designs, the lens array 21 (i) can have attachment points designed to maintain alignment after temperature excursions/cycles; (ii) can have a heat path to inhibit overheating and misalignment due to thermal loading; (iii) can be bonded to a coefficient of thermal expansion matched lens frame (not shown) with a thin adhesive bond line, and/or (iv) can be attached by thermally-conductive epoxy or solder to a metal lens frame.

[0098] With reference to Figure 1C, with the present design, each of the colliminated laser beams 50A-50F will be incident on the beam combiner 24 on the combiner focal plane 24A at a different angle of incidence 56 (relative a normal 24B of a combiner surface 24C of the beam combiner 24). More specifically, with reference to Figure 1 C, (i) the collimated first laser beam 50A will have a first angle of incidence 56a relative to normal 24B of the beam combiner 24 (illustrated as a box); (ii) the collimated second laser beam 50B will have a second angle of incidence 56b relative to normal 24B of the beam combiner 24; (iii) the colliminated third laser beam 50C will have a third angle of incidence 56c relative to normal 24B of the beam combiner 24; (iv) the colliminated fourth laser beam 50D will have a fourth angle of incidence 56d relative to normal 24B of the beam combiner 24; (v) the colliminated fifth laser beam 50E will have a fifth angle of incidence 56e relative to normal 24B of the beam combiner 24; and (vi) the colliminated sixth laser beam 50E will have a sixth angle of incidence 56e relative to normal 24B of the beam combiner 24. Further, each angle of incidence 56a-56f will be different.

[0099] In the non-exclusive implementation of Figure 1 C, the angle of incidence 56a-56f increases from first angle of incidence 56a to the sixth angle of incidence 56f.

[00100] The amount of difference between the angles of incidence 56a-56f can be varied to achieve the desired configuration of the laser assembly 10. As alternative, non-exclusive examples, a difference in angle of incidence 56a-56f between adjacent beams can be at least approximately 0.01 , 0.1 , 1 , 3, 5, 10, or 15 degrees.

[00101] Figure 1 C also illustrates that the beam combiner 24 has transformed and combined the collimated emitter beams 50A-50F into a multi-specral combination beam 58 that is directed along the output axis 12A. Stated differently, in Figure 1 C, the emitter beams 50A-50F overlap on the beam combiner 24 (e.g., wavelength anguler dispersive element), and each emitter beam 50A-50F is incident at a different angle on the beam combiner 24.

[00102] In the embodiment of Figure 1 C, the combination beam 58 is made up of the colliminated laser beams 50A-50F that are directed by the beam combiner 24 to be substantially parallel and overlapping. Further, the combination beam 58 has minimal degradation when compared to the original laser beams 50A-50F. In certain embodiments, the beam quality of the combination beam 58 is not greatly degraded over the beam quality of the individual beams 50A-50F. In one specific embodiment, a M-squared value of the combination beam 58 is not much larger than a M-squared value of an individual beam. For example, the M-squared value of the combined beam can be between 1.1 -1.2 and the M-squared value of each of the individual beams can be between 1.1-1 .2.

[00103] With reference back to Figure 1A, in this implementation, the beam combiner 24 has directed the combination beam 58 at the output coupler 26. The design of the beam combiner 24 can be varied to adjust the characteristics of the assembly output beam 12. In one embodiment, the beam combiner 46 is a wavelength selective, dispersive beam combiner, such as a diffraction grating (i) having high diffraction efficiency for a wide range of angles of incidences; (ii) that can handle forward and reverse propagating beams; (iii) that is designed for high power; (iv) that is photo-etched, ruled, replicated, gray scale, binary; (v) that has low scatter; (vi) that has a low coefficient of thermal expansion, (vii) that has high optical flatness, and/or (vii) that is optimized for the wavenumbers of the emitters 18. In Figure 1A, the beam combiner 24 is a reflective diffraction grating that can be aluminum, silver, or gold coated. In this embodiment, the diffraction grating 24 is a plate that includes a large number of very fine parallel grooves that have an inter-groove spacing referred to as the grating pitch (“GP”).

[00104] Alternatively, the beam combiner 24 can be a wavelength selective, transmission grating that is transmissive to the wavelengths generated by the emitter 18 and coated on both sides with appropriate anti-reflective coatings. Still alternatively, the beam combiner 24 can be a single prism, or diffractive optical element (DOE).

[00105] With reference to Figures 1A and 1 B, the beam combiner 24 can be positioned so that its focal plane 24A is (i) substantially parallel to the emitter array axis 17a; (ii) substantially parallel to the lens array axis 21 a; (iii) substantially perpendicular to each emitter axis 44A-44F; and/or (iv) substantially perpendicular to each lens axis 48A-48F.

[00106] It should be noted that with the design illustrated in Figure 1A, each beam 50A-50F will exit the beam combiner 246 at substantially the same angle relative to focal plane 24A to form the combination beam 58.

[00107] With reference to Figure 1 A, the output coupler 26 (i) transmits a portion of the combination beam 58 as the assembly output beam 12, and (ii) redirects a portion of the combination beam 58 as a multi-spectral, redirected beam 60 (dashed arrow) back at the beam combiner 24 and subsequently to the respective emitters 18. With this design, the output coupler functions as a common, second cavity end for each emitter 18. As a result thereof, each emitter 18 has a separate external cavity that is defined by the back facet 18G (illustrated in Figure 1 B) of the respective emitter 18, and the common output coupler 26. Thus, each emitter 18 operates in a separate external cavity independent from the other emitters 18.

[00108] Further, as provided herein, the length of the external cavity for each emitter 18 is slightly different. Thus, each emitter 18 will lase at a different center wavenumber, even if the characteristics of each of the emitters 18 are identical. More specifically, the first emitter beam 20A, the second emitter beam 20B, the third emitter beam 20C, the fourth emitter beam 20D, the fifth emitter beam 20E, and the emitter laser beam 20F will each lase at a different center wavenumber. Stated in a different fashion, the specific center wavenumber of the emitter beam 20 generated by each emitter 18 is tied to an angle of incidence 56 (illustrated in Figure 1C) of its respective collimated beam 50A-50F on the beam combiner 24. Further, the angle of incidence of each collimated beam 50A-50F on the beam combiner 24 is tied to emitter pitch and the lens pitch.

[00109] It should be noted that the spacing of the emitters 18 will create different external cavity lengths, and each emitter 18 will lase at a slightly different center frequency. Further, the wavelength selectivity of the beam combiner 24 (e.g., grating) will allow for the different lasing frequencies. Thus, together, the beam combiner 24 and the different cavity length for each of the emitters 18 will result in the multispectral output beam 12.

[00110] In the external cavity arrangements disclosed herein, the design of the beam combiner 24, and the angle of incidence 56a-56f (illustrated in Figure 1 C) of each collimated laser beam 50A-50F on the beam combiner 24 will dictate what wavelength will experience the least loss per round trip in the external cavity and thus dominate the center wavenumber of the respective emitter 20. Thus, the spectral width of the assembly output beam 12, and the individual center wavenumber that each emitter 18 is lasing at, can be selected by the arrangement of the emitter array 17 and the lens array 38.

[00111] In Figure 1A, the output coupler 26 is positioned on the output axis 12A and functions as the second defining boundary of the external cavity for each emitter 18. In the simplified illustration of Figure 1A, the output coupler 26 is an optical element that includes a first coupler side 26A that is coated with a partly reflective coating that is optimized to maximize extraction efficiency for all emitters 18, and a second coupler side 28B that is coated with an anti-reflective coating. With this design, the first coupler side 28A cooperates with the back facet 18G (illustrated in Figure 1 B) of each emitter 18 to form the external cavity for each emitter 18. Stated in another fashion, in this design, the first coupler side 26A redirects at least a portion of the combination beam 58 back to the beam combiner 24 as the multi-spectral redirected beam 60 (illustrated as a dashed line), and transmits a portion of the combination beam 58 as the multi-spectral assembly output beam 12 along the output axis 12A.

[00112] In one non-exclusive embodiment, (i) the first coupler side 26A has a reflectivity of between approximately one to thirty percent, (ii) the output coupler 26 has a high thermal conductivity; and (iii) the anti-reflective coated second coupler side 26B reduces optical losses.

[00113] The redirected beam 60 reflected by the output coupler 60 retraces the path back to the beam combiner 24, with the beam combiner 24 now acting as chromatic beam splitter which directs the returning beams of distinct wavenumbers to their respective emitters 18. Explicitly, the multi-spectral redirected beam 60 is incident on the beam combiner 24 at the same angle (e.g. relative to normal 24B), but will create different laser beams exiting from the beam combiner 24 at different angles (which correspond to the angle of incidences 56a-56f), based on the respective wavenumbers in the redirected beam 60. Stated in another fashion, each laser beam returning from the beam combiner 24 will be at a different return angle based on wavenumber, these angles being, by wavenumber, the same as the incident angles. In turn, the wavenumber-distinct optical feedback to each of the individual emitters creates the lowest-loss condition for that emitter thereby driving the individual emitter 18 to resonate (“lase”) at that wavenumber. Thus, with the present design, each emitter 18 in combination with the external optics comprises a laser lasing with a center wavenumber dictated by geometry, and specifically dictated by the position of the individual emitter 18 and its corresponding lens 22 within the array.

[00114] In certain implementations, as provided herein, the output coupler 26 can be uniquely designed to be optomechanically insensitive to the position of the output coupler 26 relative to the multispectral combination beam 58 about one or more axes. For example, the output coupler 26 can be designed to be insensitive to the angular position of the output coupler 26 relative to the incoming beam 58 in the pitch, yaw, and roll. With this design, slight drifts in the relative position of the beam combiner 24, the output coupler 26, the emitters 18, and/or the lenses 22 will not result in significant loss of intensity of the output beam 12, and will not cause the external cavities to become unstable. As a result, the laser assembly 10 is optomechanically insensitive to slight movement of the components.

[00115] As provided herein, the desirable modes of the external cavity propagate between the high reflectivity coated facet of their respective individual emitter 18 and the output coupler 26, in a manner that for each mode the beam is normal to the output coupler 26. The portions of the beams transmitted thru the output coupler 26 travel concentrically and colinearly to each other, forming the high quality assembly output beam 12. The portions of the beams reflected off of the output coupler 26 return to their corresponding emitters 18, rather than neighboring emitters 18.

[00116] It should be noted that when the output coupler 26 is misaligned, crosstalk can occur. Crosstalk is a phenomenon when, for example, when beams are reflected off of the output coupler 26 at the slightly wrong angle. This can cause one or more emitters 18 to lase at one or more undesirable modes. This can reduce the intensity of the output beam 12 and reduce the lasing stability of the emitters 18. Also, crosstalk can occur in an aligned cavity depending on the cavity geometry and the efficiency of one emitter to couple into another emitter. These are undesired because those modes wll hurt the beam quality (brightness) of the laser assembly 10. [00117] A number of non-excluisve examples, of the optomechanically insensitive output couplers 26 are described in more detail below.

[00118] The system controller 28 controls the operation of the components of the laser assembly 10. For example, the system controller 28 can include one or more processors 28A, and one or more electronic storage devices 28B. In certain embodiments, the system controller 28 can control the electron injection current to the individual emitters 18, and control the thermal controller 40 to control the temperature of the mounting base 38A. The system controller 28 can be a centralized or distributed system.

[00119] In certain embodiments, the system controller 28 individually directs current to each of the emitters 18. For example, the system controller 28 can continuously direct power to one or more of the emitters 18. Alternatively, for example, the system controller 28 can direct power in a pulsed fashion to one or more of the emitters 18. In one embodiment, the duty cycle is approximately fifty percent. Alternatively, the duty cycle can be greater than or less than fifty percent.

[00120] It should be noted that in the pulsed mode of operation, the system controller 28 can simultaneous direct pulses of power to each of the emitters 18 so that each of the emitters 18 generates the respective emitter beams 20 at the same time. In this design, the assembly output beam 12 is multi-spectral and made up the combined individual emitter beams 20.

[00121] Alternatively, the system controller 28 can direct pulses of power to one or more of the emitters 18 at different times so that the emitters 18 generate the respective emitter beam 20 at different times. In this design, the characteristics of the assembly output beam 12 can be controlled by which of the emitters 18 are currently activated. For example, in this design, each of the emitters 18 can be activated sequentially to generate an assembly output beam 12 having a center wavenumber that changes over time. This design allows for individually controllable emitter 18 (channels) for individual wavenumber generation for spectroscopy or other applications.

[00122] As provided herein, the system controller 28 can accept analog, digital or software transmitted commands to pulse the assembly output beam 12 with the desired pulse width and repetition rate. This feature allows the user to precisely adjust the characteristics of the assembly beam 12 to meet the system requirements of the laser assembly 10. [00123] The system controller 28 can utilize voltage or light-sensing circuitry to shut down in case of failure of one or more of the emitters 18, to balance power, and/or to allow ‘digital’ spectroscopy whereby individual wavenumbers can be operated independently.

[00124] Figure 1 D is a simplified graph that illustrates a non-exclusive set of different center wavenumbers of the emitter beams 20A-20F generated by the emitters 18 (illustrated in Figure 1A). In this example, the assembly output beam 12 (illustrated in Figure 1A) will have a spectral width 62.

[00125] Figure 1 E is a simplified graph that illustrates of a non-exclusive set of different center wavenumbers versus angle of incidence. In this embodiment, the laser beams collectively have a range 64 of angles of incidence.

[00126] It should be noted that with the present design, the emitter pitch and the lens pitch can be selected to achive the desired characteristics of the assembly output beam 12.

[00127] Figure 2A is a simplified top illustration of another implementation of a laser assembly 210 that generates an assembly output beam 212 along an output axis 212A. In this implementation, the laser assembly 210 includes a laser frame 214, an emitter array 217, a lens array 221 , a system controller 228, a power supply 230, a mount 232, and a temperature controller 240 that are somewhat similar to the corresponding components described above in reference to Figure 1A. However, in the implementation of Figure 2A, the laser assembly 210 is designed without the beam combiner 24 (illustrated in Figure 1A) and the output coupler 26 (illustrated in Figure 1A).

[00128] Similarto the design of Figure 1A, (i) the emitter array 217 has an emitter pitch, (ii) the lens array 221 has a lens pitch, and (ii) the lens pitch is different from the emitter pitch. As a result thereof, the collimated beams 250 spatially overlap at a focal plane 224A. With this design, the lens array 221 will collimate each individual emitter beam 220 and point the collimated beams 250 at the focal plane 224A.

[00129] In one implementation, each emitter 218 of the emitter array 217 can be a fabry perot type laser. In this design, the front facet 218H of each emitter 218 is coated with a partly reflective coating and the back facet 218G is highly reflective. With this design, the wavelength of each emitter beam 420 will depend on the design of each emitter 418. As a result thereof, the spectral characteristics of the output beam 212 will depend upon the design of each emitter 218. [00130] In the non-exclusive implementation of Figure 2A, for example, the emitter can be designed so that the emitter beam is diverging at a first diversion rate along the X axis, and at a second (different) diversion rate along the Y axis. With this design, its corresponding lens can be designed to colliminate its beam along the Y axis, while allowing for a slight divergence along the X axis. In this design, the pitch difference between the emitter pitch and lens pitch cause the divergence in the X axis to be manipulated to be able to create a top hat shaped beam, or another beam shape. As a result thereof, each emitter beam of the assembly output beam 212 in the far field is diverging along the X axis and is collimated along the Y axis. With this design, the assembly output beam 212 will have a somewhat rectangular profile. This beam configuration can be useful for a LIDAR application or another application. Alternatively, if the lens collimates along both the X and Y axis, the assembly output beam 212 would appear as an array of spots in the far field. Thus, the lens array 221 can be designed to achieve the desired profile of the assembly output beam 212.

[00131] Figure 2B is a graph that illustrates the far field intensity of an assembly output beam along an X axis for the laser assembly of Figure 2A. Further, Figure 2C is a graph that illustrates the far field intensity of an assembly output beam along a Y axis for the laser assembly of Figure 2A. With reference to these Figures, the assembly output beam in the far field is diverging along the X axis and is collimated along the Y axis.

[00132] Figure 3 is a simplified top illustration of another embodiment of a laser assembly 310 that generates an assembly output beam 312 along an output axis 312A. In this implementation, the laser assembly 310 includes a laser frame 314, an emitter array 317, a lens array 321 , a system controller 328, a power supply 330, a mount 332, and a temperature controller 340 that are somewhat similar to the corresponding components described above in reference to Figures 1A and 2A. In the implementation of Figure 3, the laser assembly 310 is designed without the beam combiner 24 (illustrated in Figure 1A).

[00133] Similar to the designs of Figures 1A and 2A, (i) the emitter array 317 has an emitter pitch, (ii) the lens array 321 has a lens pitch, and (ii) the lens pitch is different from the emitter pitch. As a result thereof, the collimated beams 350 spatially overlap at a focal plane 324A. With this design, the lens array 321 will collimate each individual emitter beam 320 and point the collimated beams 350 at the focal plane 324A. [00134] In the implementation of Figure 3, (i) the laser assembly 310 includes an output coupler 326 that is positioned at the focal plane 324A; (ii) the front facet 318H of each emitter 318 is coated with an anti-reflective coating; and (iii) the back facet 318G is highly reflective. With this design, the output coupler 326 (i) transmits a portion of the collimated beams 350 as the assembly output beam 312, and (ii) redirects a portion of the collimated beams 350 as a multi-spectral, redirected beam back at the lens array 321 and the emitter array 317. With this design, the output coupler functions as a common, second cavity end for each emitter 318. As a result thereof, each emitter 318 has a separate external cavity that is defined by the back facet 318G (illustrated in Figure 1 B) of the respective emitter 318, and the common output coupler 326. Thus, each emitter 318 operates in a separate external cavity independent from the other emitters 318.

[00135] Further, as provided herein, the length of the external cavity for each emitter 318 is slightly different. Thus, each emitter 318 will lase at a different center wavenumber, even if the characteristics of each of the emitters 318 are identical, and the output beam 312 will be multi-spectral. This is due to the different allowed laser mode structure for each cavity length. Moreover, depending on the design of each emitter 318, each emitter 318 might have multiple wavelengths since there might not be much frequency selectivity in the emitter aside from the gain profile, unless there is some frequency selective element built into the emitter 318. With this design, the degree of being multi-spectral may be insignificant compared to the broad lasing profiles of the emitters 318 if they are not frequency selectivity.

[00136] In the non-exclusive implementation of Figure 3, the assembly output beam 312 in the far field can be diverging along the X axis, and collimated along the Y axis. Alternatively, the lens array 321 can be designed to achieve a different configuration of the assembly output beam 312 in the far field.

[00137] Figure 4 is a simplified top illustration of another embodiment of a laser assembly 410 that generates an assembly output beam 412 along an output axis 412A. In this implementation, the laser assembly 410 includes a laser frame 414, an emitter array 417, a lens array 421 , a system controller 428, a power supply 430, a mount 432, and a temperature controller 440 that are somewhat similar to the corresponding components described above in reference to Figures 1 A, 2A, and 3. In the implementation of Figure 4, the laser assembly 410 is again designed without the beam combiner 24 (illustrated in Figure 1A) and the output coupler 26 (illustrated in Figure 1A).

[00138] Similar to the designs of Figures 1A, 2A, and 3, (i) the emitter array 417 has an emitter pitch, (ii) the lens array 421 has a lens pitch, and (ii) the lens pitch is different from the emitter pitch. As a result thereof, the collimated beams 450 spatially overlap at a focal plane 424A. With this design, the lens array 421 will collimate each individual emitter beam 420 and point the collimated beams 450 at the focal plane 424A.

[00139] In the implementation of Figure 4, (i) the front facet 418H of each emitter 418 is coated with a partly reflective coating that emits a portion of the emitter beam 420; (ii) the back facet 418G of each emitter 418 is coated with a non-reflective coating; and (iii) each emitter 418 includes a separate, wavelength selective element 466 (illustrated as a box) spaced apart from the back facet 418G. With this design, each emitter 418 is an external cavity laser that lases between its front facet 418H and its wavelength selective element 466. For example, each wavelength selective element 466 can include a diffraction grating or another type of wavelength selective element. Additionally, each emitter 418 can include an actuator that moves the grating 466 to select (tune) the center wavelength of each emitter 418 in a closed loop fashion.

[00140] With this design, the wavelength of each emitter beam 420 will depend on the design of each emitter 418, and the design and/or control of each wavelength selective element 466. Stated in another fashion, in this design, the laser assembly 410 includes a plurality of individually tunable emitters 418 that cooperate to generate the plurality of spaced apart collimated beams 450. As a result thereof, the spectral characteristics of the output beam 412 will depend upon the design and control of the emitters 418.

[00141] In the non-exclusive implementation of Figure 4, the assembly output beam 412 in the far field can be diverging along the X axis and collimated along the Y axis. Alternatively, the lens array 421 can be designed to achieve a different configuration of the assembly output beam 412 in the far field.

[00142] Figure 5A is a simplified side illustration of an output coupler 526 with a combination beam 558, a redirected beam 560, and the output beam 512. In Figure 5A, (i) the combination beam 558 is directed at and incident on the output coupler 526, and moving left to right; (ii) the redirected beam 560 is exiting the output coupler 526 moving right to left; and (iii) the output beam 512 is exiting the output coupler 526 and moving left to right.

[00143] It should be noted that the output coupler 526 of Figure 5A can be used in the laser assembly 10 of Figure 1A instead of the output coupler 26 (illustrated in Figure 1A), the laser assembly 310 of Figure 3, or in another type of laser assembly. For example, the laser assembly can be designed to have one or more emitters, and the output coupler 526 of Figure 5A that forms one end of an external cavity for the one or more emitters. In more specific example, the output coupler 526 can be used in laser assemblies in which the emitter pitch matches the lens pitch. In a nonexclusive implementation, the ouput coupler 526 illustrated in Figure 5A can be used in any of the laser assemblies illustrated and described in U.S. Patent Publication No. US2021/0351571 and entitled “Laser Assembly with Beam Combining”. As far as permitted, the contents of US2021/0351571 are incorporated herein by reference.

[00144] In Figure 5A, a central combination beam axis 558A of the combination beam 558; an output axis 512A of the output beam 512; and a central, coupler axis 526C of the output coupler 526 are also illustrated. At this time, the output coupler 526 is precisely aligned with the comination beam 558. As a result thereof, the coupler coupler axis 526C is coaxial with the central combination beam axis 558A and the output axis 512A.

[00145] Figure 5A also includes a beam orientation system that is referenced to the combination beam 558. In Figure 5, the beam orientation system illustrates a first beam axis (“b1 axis”), a second beam axis (“b2 axis”) that is orthogonal to the b1 axis, and a third beam axis (“b3 axis”) that is orthogonal to the b1 and b2 axes. It should be noted that any of these beam axes can also be referred to as the first, second, and/or third axes. In Figure 5A, the b3 axis is parallel to the combination beam axis 558A, and the b1 and be2 axes are perpendicular to the combination beam axis 558.

[00146] Figure 5A illustrates a non-exclusive implementation of the output coupler 526 that is uniquely designed to be optomechanically insensitive to the position of the output coupler 526 relative to the combination beam 558 about two of more axes. For example, the output coupler 526 can be designed to be insensitive to the angular position of the output coupler 526 relative to the incoming beam 558 in the pitch (rotation about the b2 axis), yaw (rotation about the b1 axis), roll (rotation about the b3 aixs). With this design, slight drifts in the relative position of the beam combiner 24 (illustrated in Figure 1A) output coupler 526, the emitters 18 (illustrated in Figure 1 A), and/or the lenses 22 (illustrated in Figure 1A) will not result in significant loss of intensity of the output beam 512, and will not cause the external cavities to become unstable and/or lose power.

[00147] The design of the output coupler 526 can be varied pursuant to the teachings provided herein. In the non-excluisve implementation of Figure 5A, the output coupler 526 includes (i) a first optical element 526D that focuses light, (ii) a partially reflective element 526E, and (iii) a second optical element 526F that are spaced apart along the coupler axis 526C. For example, each element 526D, 526F can be a axisymeteric, and can be a spherical lens, an aspherical lens, or a mirror. In a specific example, the second optical element 526F can be a collimating lens.

[00148] Further, for example, the partially reflective element 526E can be a transmissive element 526G that includes a partly reflective coating 526H that is optimized to maximize extraction efficiency for all emitters, and a second coupler side that is coated with an anti-reflective coating. In one non-exclusive embodiment, (i) the reflective coating 526H has a reflectivity of between approximately one to thirty percent, (ii) the element 526E has a high thermal conductivity; and (iii) the anti- reflective coated second coupler side reduces optical losses.

[00149] With the design of Figure 5A, the output coupler 526 is insensitive to (i) misalignment in yaw to maintain the wavelength stability of each emitter; and misalignment in pitch to maintain the power output stability.

[00150] Figure 5B is a simplified illustration of a front view of the partially refective element 526E with the combination beam 558 directed thereon. In the design of Figure 5A, the first focusing element 526D focuses the combination beam 558 as a spot at the center of the partially refective element 526E. Thus, the spot will have a high power intensity, and the partially reflective element 526E must be designed to withstand the localized heat. The localized heat can damage the partly reflective coating of the partially reflective element 526E unless the partially reflective element 526E is properly designed. Moreover, the localized heat can change the optical properties of the partially reflective element 526E unless the partially reflective element 526E is properly designed.

[00151] Futher, with reference to Figures 5A and 5B, because the combination beam 558 is focused as a spot, the redirected beam 560 will reflect from the partially reflective element 526E and return back and through the first focusing element 526D along the combination beam axis 558A even if misaligned in pitch and yaw. [00152] Figure 6A is a simplified side illustration of another implementation of an output coupler 626 with a combination beam 658, a redirected beam 660, and the output beam 612. In Figure 6A, (i) the combination beam 658 is directed at and incident on the output coupler 626, and moving left to right; (ii) the redirected beam 660 is exiting the output coupler 626 moving right to left; and (iii) the output beam 612 is exiting the output coupler 626 and moving left to right.

[00153] It should be noted that the output coupler 626 of Figure 6A can be used in the laser assembly 10 of Figure 1A instead of the output coupler 26 (illustrated in Figure 1A), the laser assembly 310 of Figure 3, or in another type of laser assembly. For example, the laser assembly can be designed to have one or more emitters, and the output coupler 626 of Figrue 6A that forms one end of an external cavity for the one or more emitters. In more specific example, the output coupler 626 can be used in laser assemblies in which the emitter pitch matches the lens pitch. In a nonexclusive implementation, the ouput coupler 626 illustrated in Figure 6A can be used in any of the laser assemblies illustrated and described in U.S. Patent Publication No. US2021/0351571 and entitled “Laser Assembly with Beam Combining”.

[00154] In Figure 6A, a central combination beam axis 658A of the combination beam 658; an output axis 612A of the output beam 612; and a central, coupler axis 626C of the output coupler 626 are also illustrated. At this time, the output coupler 626 is precisely aligned with the comination beam 658. As a result thereof, the coupler coupler axis 626C is coaxial with the central combination beam axis 658A and the output axis 612A.

[00155] Figure 6A also includes the same beam orientation system as described above in reference to Figure 5A.

[00156] Figure 6A illustrates a non-exclusive implementation of the output coupler 626 that is uniquely designed to be optomechanically insensitive to the position of the output coupler 626 relative to the combination beam 658 about only two axes. For example, the output coupler 626 can be designed to be insensitive to the angular position of the output coupler 626 relative to the incoming beam 658 in the pitch (rotation about the b2 axis), and roll (rotation about the b3 aixs). With this design, slight drifts in the relative position of the beam combiner 24 (illustrated in Figure 1A) output coupler 626, the emitters 18 (illustrated in Figure 1A), and/or the lenses 22 (illustrated in Figure 1 A) will not result in significant loss of intensity of the output beam 612. [00157] The design of the output coupler 626 can be varied pursuant to the teachings provided herein. In the non-excluisve implementation of Figure 6A, the output coupler 626 includes (i) a first optical element 626D that focuses light, (ii) a partially reflective element 626E, and (iii) a second optical element 626F that are spaced apart along the coupler axis 626C that are somewhat similar to the corresponding components described above and illustrated in Figure 5A. However, in the implementation of Figure 6A, each element 626D, 626F can be a single axis optical element, and can be a cylindrical lens, an acylidrical lens, or a mirror.

[00158] With the design of Figure 6A, the output coupler 626 is insensitive to misalignment in pitch to maintain the power output stability.

[00159] Figure 6B is a simplified illustration of a front view of the partially refective element 626E with the combination beam 658 directed thereon. In the design of Figure 6A, the first focusing element 626D focuses the combination beam 658 as a single focused line on the partially refective element 626E. Thus, In Figure 6B, the heat from the combination beam 658 is more distributed. Because the heat is distributed on the partly reflective coating of the partially reflective element 526E, the partly reflective coating is less likely to overheat and fail, and/or the optical properties of the partially reflective element 526E is less likely to change.

[00160] Futher, with reference to Figures 6A and 6B, because the combination beam 658 is focused as a line, the redirected beam 660 will reflect from the partially reflective element 626E and return back and through the first focusing element 626D along the combination beam axis 658A even if misaligned in pitch.

[00161] Figure 7A is a simplified side illustration of yet another implementation of an output coupler 726 with a combination beam 758, a redirected beam 760, and the output beam 712. In Figure 7A, (i) the combination beam 758 is directed at and incident on the output coupler 726, and moving left to right; (ii) the redirected beam 760 is exiting the output coupler 726 moving right to left; and (iii) the output beam 712 is exiting the output coupler 726 and moving left to right.

[00162] It should be noted that the output coupler 726 of Figure 7A can be used in the laser assembly 10 of Figure 1A instead of the output coupler 26 (illustrated in Figure 1A), the laser assembly 310 of Figure 3, or in another type of laser assembly. For example, the laser assembly can be designed to have one or more emitters, and the output coupler 726 of Figrue 7A that forms one end of an external cavity for the one or more emitters. In more specific example, the output coupler 726 can be used in laser assemblies in which the emitter pitch matches the lens pitch. In a nonexclusive implementation, the ouput coupler 726 illustrated in Figure 7A can be used in any of the laser assemblies illustrated and described in U.S. Patent Publication No. US2021/0351571 and entitled “Laser Assembly with Beam Combining”.

[00163] In Figure 7A, a central combination beam axis 758A of the combination beam 758; an output axis 712A of the output beam 712; and a central, coupler axis 726C of the output coupler 726 are also illustrated. At this time, the output coupler 726 is precisely aligned with the comination beam 758. As a result thereof, the coupler coupler axis 726C is coaxial with the central combination beam axis 758A and the output axis 712A.

[00164] Figure 7A also includes the same beam orientation system as described above in reference to Figure 5A.

[00165] Figure 7A illustrates another, non-exclusive implementation of the output coupler 726 that is uniquely designed to be optomechanically insensitive to the position of the output coupler 726 relative to the combination beam 758 about two axes. For example, the output coupler 726 can be designed to be insensitive to the angular position of the output coupler 726 relative to the incoming beam 758 in the pitch (rotation about the b2 axis), and roll (rotation about the b3 aixs). With this design, slight drifts in the relative position of the beam combiner 24 (illustrated in Figure 1A) output coupler 726, the emitters 18 (illustrated in Figure 1A), and/or the lenses 22 (illustrated in Figure 1 A) will not result in significant loss of intensity of the output beam 712.

[00166] In the non-excluisve implementation of Figure 7A, the output coupler 726 includes (i) a partiallly reflective prism 726I, (ii) a first triangular shaped element 726J; and (iii) a second triangular shaped element 726K that are arranged to form a rectangular cube. In this implementation, the partially reflective prism 726I can be a partially reflective porro prism that receives the combination beam 758, redirects at least a portion of the combination beam 758 back as the redirected beam 760, and transmits a portion of the combination beam 758 as the assembly output beam 712. In this design, the porro prism 728I has a triangular shaped cross-section and includes (i) an anti-reflective front surface 728la, (ii) a first partially reflective surface 726I b; and (iii) a second partially reflective surface 726lc. Each partially reflective surface 726lb, 726lc can be similar to the partially reflective surfaces described above. Each triangular shaped element 726J, 726K can be transparent to the wavelengths of the combination beam 758.

[00167] With the design of Figure 7 A, the output coupler 726 is insensitive to misalignment in pitch to maintain the power output stability.

[00168] It should be noted that with the design of Figure 7A, the combination beam 758 incident on the partially reflective surfaces surfaces 726lb, 726lc of the partially reflective prism 726I will also result in a first transverse portion 770a and a second transverse portion 770b exiting the output coupler 726 transverse to the coupler axis 726C.

[00169] Figure 7B is a simplified illustration of a front view of the partially refective surfaces 726lb, 726lc with the combination beam 758 directed thereon. In the design of Figure 7A, the combination beam 758 is distribued on the partially refective surfaces 726lb, 726I and thus are subjected to low power intensity on the coatings. Thus, In Figure 7B, the heat from the combination beam 658 is more distributed.

[00170] Figure 8 is a simplified side illustration of still another implementation of an output coupler 826 with a combination beam 858, a redirected beam 860, and the output beam 812. In Figure 8, (i) the combination beam 858 is directed at and incident on the output coupler 826, and moving left to right; (ii) the redirected beam 860 is exiting the output coupler 826 moving right to left; and (iii) the output beam 812 is exiting the output coupler 826 and moving left to right.

[00171] It should be noted that the output coupler 826 of Figure 8 can be used in the laser assembly 10 of Figure 1A instead of the output coupler 26 (illustrated in Figure 1A), the laser assembly 310 of Figure 3, or in another type of laser assembly. For example, the laser assembly can be designed to have one or more emitters, and the output coupler 826 of Figrue 8 that forms one end of an external cavity for the one or more emitters. In more specific example, the output coupler 826 can be used in laser assemblies in which the emitter pitch matches the lens pitch. In a non-exclusive implementation, the ouput coupler 826 illustrated in Figure 8 can be used in any of the laser assemblies illustrated and described in U.S. Patent Publication No. US2021/0351571 and entitled “Laser Assembly with Beam Combining”.

[00172] In Figure 8, a central combination beam axis 858A of the combination beam 858; an output axis 812A of the output beam 812; and a central, coupler axis 826C of the output coupler 826 are also illustrated. At this time, the output coupler 826 is precisely aligned with the comination beam 858. As a result thereof, the coupler coupler axis 826C is coaxial with the central combination beam axis 858A and the output axis 812A.

[00173] Figure 8 also includes the same beam orientation system as described above in reference to Figure 5A.

[00174] Figure 8 illustrates another, non-exclusive implementation of the output coupler 826 that is uniquely designed to be optomechanically insensitive to the position of the output coupler 826 relative to the combination beam 858 about two axes. For example, the output coupler 826 can be designed to be insensitive to the angular position of the output coupler 826 relative to the incoming beam 858 in the pitch (rotation about the b2 axis), and roll (rotation about the b3 aixs). With this design, slight drifts in the relative position of the beam combiner 24 (illustrated in Figure 1A) output coupler 826, the emitters 18 (illustrated in Figure 1A), and/or the lenses 22 (illustrated in Figure 1 A) will not result in significant loss of intensity of the output beam 812.

[00175] Similar to the implementation of Figure 7A, the output coupler 826 in Figure 8 includes (i) a partiallly reflective prism 826I, (ii) a first triangular shaped element 826J; and (iii) a second triangular shaped element 826K that are arranged to form a rectangular cube. These components can be similar to the corresponding components described above and illustrated in Figure 7A.

[00176] With the design of Figure 8, the output coupler 826 is insensitive to misalignment in pitch to maintain the power output stability.

[00177] It should be noted that with the design of Figure 8, the combination beam 858 incident on the partially reflective surfaces surfaces 826I b, 826lc of the partially reflective prism 826I will also result in a first transverse portion 870a and a second transverse portion 870b exiting the partially reflective prism 826I transverse to the coupler axis 826C.

[00178] However, in the implementation of Figure 8, the output coupler 826 can additionally include (i) a first beam redirector 826L that redirects the first transverse portion 870a back to the partly reflective prism 826I; and (ii) a second beam redirector 826M that redirects the second transverse portion 870b back to the partly reflective prism 826I. With this design, the transverse portion 870a, 870b are returned as a portion of the output beam 812 and a portion of the redirected beam 860. This improves the efficiency of the laser assembly by not wasting light. [00179] As non-exclusive examples, each beam redirector 826L, 826M can be a total internal reflective porro prism or another type of retro- reflector.

[00180] It should be noted that in certain embodiments, that the beam redirectors 826L, 826M are aligned and positioned for constructive interference of all three output beams.

[00181] While the particular designs as shown and disclosed herein is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.

Claims

What is claimed is:

1. A laser assembly that generates an assembly output beam, the laser assembly comprising: an emitter array including a first emitter that generates a first emitter beam along a first emitter axis, and a second emitter that generates a second emitter beam along a second emitter axis, wherein the first emitter axis and the second emitter axis are spaced apart a first emitter separation distance; and a lens array including a first lens that colliminates the first emitter beam, and a second lens that colliminates the second emitter beam, wherein the first lens has a first lens axis and the second lens has a second lens axis, and wherein the first lens axis and the second lens axis are spaced apart a first lens separation distance that is different from the first emitter separation distance.

2. The laser assembly of claim 1 wherein the emitter array including a third emitter that generates a third emitter beam along a third emitter axis; wherein the third emitter axis and the second emitter axis are spaced apart a second emitter separation distance; wherein the lens array includes a third lens that colliminates the third laser beam; wherein the third lens has a third lens axis; and wherein the third lens axis and the second lens axis are spaced apart a second lens separation distance that is different from the second emitter separation distance.

3. The laser assembly of claim 1 wherein the first laser beam is in a first spectral range and the second laser beam is in a second spectral range that is different from the first spectral range.

4. The laser assembly of claim 1 wherein the first lens directs the collimated first emitter beam at a first beam angle relative to the first emitter axis; wherein the second lens directs the collimated second emitter beam at a second beam angle relative to the second emitter axis; and wherein at least one of the beam angles has an absolute value that is not zero.

5. The laser assembly of claim 4 wherein each of the beam angles has an absolute value that is not zero.

6. The laser assembly of claim 4 wherein at least one of the beam angles has an absolute value that is greater than one milliradians.

7. The laser assembly of claim 4 wherein at least one of the beam angles has an absolute value that is greater than twenty-five milliradians.

8. The laser assembly of claim 1 wherein the first lens axis is spaced apart a first offset from the first emitter axis.

9. The laser assembly of claim 8 wherein the second lens axis is spaced apart a second offset from the second emitter axis.

10. The laser assembly of claim 8 wherein the first offset is at least 0.001 millimeters.

11. The laser assembly of claim 8 wherein the first offset is at least 0.1 millimeters.

12. The laser assembly of claim 1 wherein the first lens separation distance is at least 0.1 percent different than the first emitter separation distance.

13. The laser assembly of claim 1 wherein the first lens separation distance is at least one percent different than the first emitter separation distance.

14. The laser assembly of claim 1 further comprising a beam combiner that combines the collimated first emitter beam and the collimated second emitter beam into a combination beam, wherein the beam combiner has a combiner surface having a normal; wherein the first lens directs the collimated first emitter beam at a first angle of incidence relative to normal on the beam combiner; wherein the second lens directs the collimated second emitter beam at a second angle of incidence relative to normal on the beam combiner; and wherein the second angle of incidence is different from the first angle of incidence.

15. The laser assembly of claim 11 further comprising an output coupler (i) that receives the combination beam from the beam combiner, (ii) that transmits a portion of the combination beam to provide the assembly output beam, and (ii) that redirects a portion of the combination beam back at the beam combiner; wherein the output coupler is optomechanically insensitive to the position of the output coupler relative to the combination beam along at least one axis.

16. A laser assembly that generates an assembly output beam, the laser assembly comprising: an emitter array including (i) a first emitter that generates a first emitter beam, the first emitter having a first emitter axis, and (ii) a second emitter that generates a second emitter beam, the second emitter having a second emitter axis; and a lens array including (i) a first lens that colliminates the first emitter beam and directs the collimated first emitter beam at a first beam angle relative to the first emitter axis; and (ii) a second lens that colliminates the second emitter beam and directs the collimated second emitter beam ata second beam angle relative to the second emitter axis; wherein at least one of the beam angles has an absolute value that is not zero.

17. The laser assembly of claim 16 wherein each of the beam angles has an absolute value that is not zero.

18. The laser assembly of claim 16 wherein at least one of the beam angles has an absolute value that is greater than four milliradians.

19. The laser assembly of claim 16 wherein at least one of the beam angles has an absolute value that is greater than twenty-five milliradians.

20. The laser assembly of claim 16 further comprising a beam combiner that combines the collimated first emitter beam and the collimated second emitter beam into a combination beam, wherein the beam combiner has a combiner surface having a normal; wherein the first lens directs the collimated first emitter beam at a first angle of incidence relative to normal on the beam combiner; wherein the second lens directs the collimated second emitter beam at a second angle of incidence relative to normal on the beam combiner; and wherein the second angle of incidence is different from the first angle of incidence.

21 . The laser assembly of claim 20 further comprising an output coupler (i) that receives the combination beam from the beam combiner, (ii) that transmits a portion of the combination beam to provide the assembly output beam, and (ii) that redirects a portion of the combination beam back at the beam combiner; wherein the output coupler is optomechanically insensitive to the position of the output coupler relative to the combination beam about at least one axis.

22. A laser assembly that generates an assembly output beam, the laser assembly comprising: a laser array including a first emitter that generates a first emitter beam along a first emitter axis, and a second emitter that generates a second emitter beam along a second emitter axis; and a lens array including a first lens that colliminates the first emitter beam, and a second lens that colliminates the second emitter beam, wherein the first lens has a first lens axis and the second lens has a second lens axis, and wherein the first lens axis is spaced apart a first offset from the first emitter axis.

23. The laser assembly of claim 22 wherein the second lens axis is spaced apart a second offset from the second emitter axis.

24. The laser assembly of claim 22 wherein the first offset is at least 0.001 millimeters.

25. The laser assembly of claim 22 further comprising a beam combiner that combines the collimated first emitter beam and the collimated second emitter beam into a combination beam, wherein the beam combiner has a combiner surface having a normal; wherein the first lens directs the collimated first emitter beam at a first angle of incidence relative to normal on the beam combiner; wherein the second lens directs the collimated second emitter beam at a second angle of incidence relative to normal on the beam combiner; and wherein the second angle of incidence is different from the first angle of incidence.

26. The laser assembly of claim 25 further comprising an output coupler (i) that receives the combination beam from the beam combiner, (ii) that transmits a portion of the combination beam to provide the assembly output beam, and (ii) that redirects a portion of the combination beam back at the beam combiner; wherein the output coupler is optomechanically insensitive to the position of the output coupler relative to the combination beam about at least one axis.

27. A laser assembly that generates an assembly output beam, the laser assembly comprising: an emitter array including a plurality of emitters that are spaced apart to have an emitter pitch, the emitters cooperating to emit a plurality of emitter beams when power is directed to the emitter array; and a lens array that collimates the plurality of emitter beams, the lens array including a plurality of lenses that are spaced apart to have a lens pitch that is different from the emitter pitch.

28. The laser assembly of claim 27 further comprising a beam combiner that combines the collimated emitter beams into a combination beam, wherein the beam combiner has a combiner surface having a normal; and wherein the lens array directs the collimated emitter beams to overlap on the beam combiner with each of the collimated emitter beams having a different angle of incidence relative to normal.

29. The laser assembly of claim 28 further comprising an output coupler (i) that receives the combination beam from the beam combiner, (ii) that transmits a portion of the combination beam to provide the assembly output beam, and (iii) that redirects a portion of the combination beam back at the beam combiner; wherein the output coupler is optomechanically insensitive to the position of the output coupler relative to the combination beam along at least one axis.

30. A laser assembly that generates an assembly output beam, the laser assembly comprising: a laser array that generates a combination beam; and an output coupler that acts as an output coupler for the laser array; the output coupler receiving the combination beam, redirecting at least a portion of the combination beam back to the laser array, and transmitting a portion of the combination beam as the assembly output beam; wherein the output coupler is optomechanically insensitive to the position of the output coupler relative to the combination beam about at least two axes.

31. The laser assembly of claim 30 wherein the output coupler is optomechanically insensitive to the position of the output coupler relative to the combination beam about three axes.

32. The laser assembly of claim 30 wherein the output coupler includes a first optical element, a partly reflective element and a second optical element that are positioned along a coupler axis.

33. The laser assembly of claim 32 wherein the first optical element is an axisymmetric focusing element that focuses the combination beam at an area on the partly reflective element.

34. The laser assembly of claim 32 wherein the first optical element focuses the combination beam along one axis on the partly reflective element.

35. The laser assembly of claim 30 wherein the output coupler includes a partly reflective prism that receives the combination beam, redirects at least a portion of the combination beam back to the laser array, and transmits a portion of the combination beam as the assembly output beam.

36. The laser assembly of claim 35 wherein the partly reflective prism directs a transverse portion of the comination beam traverse to coupler axis, and wherein the output coupler includes a beam redirector that redirects the transverse portion back to the partly reflective prism.

37. A method for generating an assembly output beam, the method comprising: generating a first emitter beam along a first emitter axis with a first emitter; generating a second emitter beam along a second emitter axis with a second emitter, wherein the first emitter axis and the second emitter axis are spaced apart a first emitter separation distance; colliminating the first emitter beam with a first lens having a first lens axis; and colliminating the second emitter beam with a second lens having a second lens axis, wherein the first lens axis and the second lens axis are spaced apart a first lens separation distance that is different from the first emitter separation distance.

38. The method of claim 37 comprising (i) generating a third emitter beam along a third emitter axis with a third emitter; wherein the third emitter axis and the second emitter axis are spaced apart a second emitter separation distance; and (ii) colliminating the third laser beam with a third lens having a third lens axis; and wherein the third lens axis and the second lens axis are spaced apart a second lens separation distance that is different from the second emitter separation distance.

39. A method for generating an assembly output beam, the method comprising: generating a first emitter beam along a first emitter axis with a first emitter; generating a second emitter beam along a second emitter axis with a second emitter; colliminating and directing the first emitter beam with a first lens at a first beam angle relative to the first emitter axis; and colliminating and directing the second emitter beam with a second lens at a second beam angle relative to the second emitter axis; wherein at least one of the beam angles has an absolute value that is not zero.

40. The method of claim 39 wherein each of the beam angles has an absolute value that is not zero.

41. A method for generating an assembly output beam, the method comprising: generating a first emitter beam along a first emitter axis with a first emitter; generating a second emitter beam along a second emitter axis with a second emitter; colliminating the first emitter beam with a first lens having a first lens axis, wherein first lens axis is spaced apart a first offset from the first emitter axis; and colliminating the second emitter beam with a second lens having a second lens axis is spaced apart a second offset from the second emitter axis.

42. A method for generating an assembly output beam, the method comprising: generating a plurality of emitter beams with an emitter array including a plurality of emitters when power is directed to the emitters, wherein the plurality of emitters are spaced apart to have an emitter pitch; and collimating the plurality of emitter beams with a lens array that includes a plurality of lenses that are spaced apart to have a lens pitch that is different from the emitter pitch.

43. A method for generating an assembly output beam, the method comprising: generating a combination beam with a laser array; and providing an output coupler for the laser array; the output coupler receiving the combination beam, redirecting at least a portion of the combination beam back to the laser array, and transmitting a portion of the combination beam as the assembly output beam; wherein the output coupler is optomechanically insensitive to the position of the output coupler relative to the combination beam about at least two axes.