POWER AND SPECTRAL MONITORING IN WAVELENGTH BEAM COMBINING LASER SYSTEMS

Abstract

In various embodiments, monitoring of one or more secondary diffracted beams formed within a laser resonator provides information based at least in part on which a primary diffracted beam formed within the laser resonator is controlled.

Claims

1.-28. (canceled)

29. A method of operating a wavelength beam combining (WBC) laser system comprising (I) a plurality of beam emitters each configured to emit a beam, (ii) transform optics for converging chief rays of the emitted beams toward a diffraction grating, (iii) a diffraction grating for receiving the beams and producing, via diffraction of the beams incident on the diffraction grating, a primary first-order diffracted beam and a secondary first-order diffracted beam, and (iv) a partially reflective output coupler positioned to receive the primary first-order diffracted beam, transmit a first portion of the primary first-order diffracted beam as a multi-wavelength output beam, and reflect a second portion of the primary first-order diffracted beam back toward the plurality of beam emitters, the method comprising: detecting power and/or spectral information from the secondary first-order diffracted beam; and controlling the plurality of beam emitters and/or the primary first-order diffracted beam based at least in part on the information.

30. The method of claim 29, wherein controlling the plurality of beam emitters and/or the primary first-order diffracted beam comprises controlling power and/or current supplied to one or more of the beam emitters based at least in part on the power and/or spectral information.

31. The method of claim 29, wherein controlling the plurality of beam emitters and/or the primary first-order diffracted beam comprises controlling a position and/or a tilt angle of at least one of (i) one or more of the beam emitters, (ii) the transform optics, (iii) the diffraction grating, or (iv) the output coupler based at least in part on the power and/or spectral information.

32. The method of claim 29, wherein (i) the diffraction grating is a transmissive diffraction grating, (ii) the primary first-order diffracted beam is a first-order transmission, and (iii) the secondary first-order diffracted beam is a first-order reflection.

33. The method of claim 29, wherein (i) the diffraction grating is a reflective diffraction grating, (ii) the primary first-order diffracted beam is a first-order reflection, and (iii) the secondary first-order diffracted beam is a first-order transmission.

34. The method of claim 29, wherein the diffraction grating produces, via diffraction of the incident beams, a zeroth-order transmission and/or a zeroth-order reflection, and further comprising detecting power and/or spectral information from the zeroth-order transmission and/or the zeroth-order reflection.

35. The method of claim 34, further comprising controlling the plurality of beam emitters and/or the primary first-order diffracted beam based at least in part on the power and/or spectral information from the zeroth-order transmission and/or the zeroth-order reflection.

36. The method of claim 35, wherein controlling the plurality of beam emitters and/or the primary first-order diffracted beam comprises controlling power and/or current supplied to one or more of the beam emitters based at least in part on the power and/or spectral information from the zeroth-order transmission and/or the zeroth-order reflection.

37. The method of claim 35, wherein controlling the plurality of beam emitters and/or the primary first-order diffracted beam comprises controlling a position and/or a tilt angle of at least one of (i) one or more of the beam emitters, (ii) the transform optics, (iii) the diffraction grating, or (iv) the output coupler based at least in part on the power and/or spectral information from the zeroth-order transmission and/or the zeroth-order reflection.

38. The method of claim 29, wherein the diffraction grating is tilted in a WBC plane with respect to the incident beams at a non-Littrow angle, whereby an angle between the incident beams and the diffraction grating in the WBC plane is different from an angle between the secondary first-order diffracted beam and the diffraction grating in the WBC plane.

39. The method of claim 29, wherein the diffraction grating is tilted in a WBC plane with respect to the incident beams at a Littrow angle, whereby an angle between the incident beams and the diffraction grating in the WBC plane is equal to an angle between the secondary first-order diffracted beam and the diffraction grating in the WBC plane.

40. The method of claim 39, wherein the diffraction grating is tilted in a non-WBC plane with respect to the incident beams at a non-Littrow angle, whereby an angle between the incident beams and the diffraction grating in the non-WBC plane is different from an angle between the secondary first-order diffracted beam and the diffraction grating in the non-WBC plane.

41. A method of operating a laser resonator, the method comprising: emitting a plurality of beams from a plurality of beam emitters; diffracting the plurality of beams to form a primary beam and one or more secondary beams; propagating a first portion of the primary beam back to the plurality of beam emitters; outputting a second portion of the primary beam; detecting power and/or spectral information from at least one said secondary beam; and controlling the plurality of beam emitters and/or the primary beam based at least in part on the power and/or spectral information from the at least one said secondary beam.

42. The method of claim 41, wherein the primary beam comprises a first-order diffracted transmission, and the one or more secondary beams comprise at least one of (i) a first-order diffracted reflection, (ii) a zeroth-order diffracted transmission, or (iii) a zeroth-order diffracted reflection.

43. The method of claim 41, wherein the primary beam comprises a first-order diffracted reflection, and the one or more secondary beams comprise at least one of (i) a first-order diffracted transmission, (ii) a zeroth-order diffracted transmission, or (iii) a zeroth-order diffracted reflection.

44. The method of claim 41, wherein controlling the plurality of beam emitters and/or the primary beam comprises controlling power and/or current supplied to one or more of the beam emitters based at least in part on the power and/or spectral information from the at least one said secondary beam.

45. The method of claim 41, wherein (i) the plurality of beams are diffracted by a diffraction grating, and (ii) the diffraction grating is tilted in a WBC plane with respect to the incident beams at a non-Littrow angle.

46. The method of claim 41, wherein (i) the plurality of beams are diffracted by a diffraction grating, and (ii) the diffraction grating is tilted in a WBC plane with respect to the incident beams at a Littrow angle.

47. The method of claim 46, wherein the diffraction grating is tilted in a non-WBC plane with respect to the incident beams at a non-Littrow angle.

48.-88. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the present invention are described with reference to the following drawings, in which:

[0043] FIG. 1 is a schematic diagram of a wavelength beam combining (WBC) laser system in accordance with embodiments of the invention;

[0044] FIG. 2 is a schematic of diffracted beams resulting from diffraction at a diffraction beam in accordance with embodiments of the invention;

[0045] FIG. 3 is a schematic of a WBC laser system with integrated monitoring capability in accordance with embodiments of the invention;

[0046] FIG. 4 is a schematic of a WBC laser system with integrated monitoring capability in accordance with embodiments of the invention;

[0047] FIG. 5A is a schematic of a WBC laser system with integrated monitoring capability, viewed in the WBC plane, in accordance with embodiments of the invention; and

[0048] FIG. 5B is a schematic of the WBC laser system of FIG. 5A, viewed in a non-WBC plane, in accordance with embodiments of the invention.

DETAILED DESCRIPTION

[0049] FIG. 1 depicts an exemplary WBC laser system 100 that utilizes one or more lasers (or “emitters” or “beam emitters”) 105. FIG. 1 is presented to illustrate the basic mechanisms of WBC, and laser systems in accordance with embodiments of the present invention may include additional elements (e.g., additional optical elements, cross-talk mitigation systems, etc.). In the example of FIG. 1, laser 105 features a diode bar having four beam emitters emitting beams 110 (see magnified input view 115), but embodiments of the invention may utilize diode bars emitting any number of individual beams or two-dimensional arrays or stacks of diodes or diode bars. In view 115, each beam 110 is indicated by a line, where the length or longer dimension of the line represents the slow diverging dimension of the beam, and the height or shorter dimension represents the fast diverging dimension. A collimation optic 120 may be used to collimate each beam 110 along the fast dimension. Transform (or “focusing”) optic(s) 125, which may include, consist essentially of, or consist of, for example, one or more cylindrical or spherical lenses and/or mirrors, are used to combine each beam 110 along a WBC direction 130. The transform optics 125 then at least partially (and, typically, substantially) overlap the combined beam onto a dispersive element 135 (which may include, consist essentially of, or consist of, e.g., a reflective or transmissive diffraction grating, a dispersive prism, a prism (prism/grating), a transmission grating, or an Echelle grating), and the combined beam is then transmitted as single output profile onto an output coupler 140. The output coupler 140 then transmits the combined beams 145 as shown on the output front view 150. The output coupler 140 is typically partially reflective and acts as a common front facet for all the laser elements in this external cavity system 100. An external cavity is a lasing system where the secondary mirror is displaced at a distance away from the emission aperture or facet of each laser emitter. In some embodiments, additional optics are placed between the emission aperture or facet and the output coupler or partially reflective surface. The output beam 145 is a thus a multiple-wavelength beam (combining the wavelengths of the individual beams 110), and may be utilized as the input beam in a laser beam delivery systems, may be utilized to process a workpiece, and/or may be coupled into an optical fiber.

[0050] FIG. 2 depicts diffraction, by an exemplary diffraction grating 200, of an incoming laser beam 210. The normal 200a to the plane of diffraction grating 200 is depicted as a dot-dashed line in FIG. 2. Diffraction at the grating 200 obeys the following Equation 1:

sin a+sin b=mpl

where m is the diffraction order (0, ±1, ±2, . . . ), p is the grating pitch (i.e., the number of lines or grooves per unit length), l is the wavelength, and the angles a and b have the same sign (positive or negative) when at the same side of the grating normal 200a.

[0051] FIG. 2 depicts a first-order diffracted transmission 220, a first-order diffracted reflection 230, a zeroth-order transmission 240, and a zeroth-order reflection 250, The first-order transmission 220 and reflection 230 obey Equation 1 with m=1 or −1, and the zeroth-order transmission 240 and reflection 250 obey Equation 1 with m=0, For the first-order diffraction, the diffraction efficiency is typically optimized at the Littrow configuration, i.e., when the angle of incidence a is equal to the first-order diffraction angle b.

[0052] High-power WBC systems typically require high-efficiency diffraction, i.e., typically utilize either the transmission 220 or the reflection 230. If a WBC system utilizes a transmissive diffraction grating, the first-order transmission 220 is typically utilized as the resonator beam, and the first-order reflection 230 will exit the resonator and is typically discarded (e.g., directed to a beam dump and/or away from the resonator). If the WBC system utilizes a reflective diffraction grating, the first-order reflection 230 typically has the highest efficiency and is utilized as the resonator beam, while the first-order transmission 220 is discarded. (Thus, as utilized herein, “transmissive” diffraction gratings are capable of transmitting, and typically do transmit, a primary diffracted beam but also reflect one or more secondary, lower-power diffracted beams. In addition, as utilized herein, “reflective” diffraction gratings are capable of reflecting, and typically do reflect, a primary diffracted beam but also transmit one or more secondary, lower-power diffracted beams, Thus, diffraction gratings are designated as “transmissive” or “reflective” based on the formation mechanism for the primary, higher-power diffracted beam, and “transmissive” does not connote the inability to reflect and vice versa.) In various implementations, since reflective gratings may feature reflective metallic coatings and may have ground back surfaces, the first-order transmission 220 and/or the zeroth-order transmission 240 may be difficult to observe.

[0053] Diffraction gratings utilized in WBC systems typically have diffraction efficiencies larger than 90%. The remaining 10% or less becomes power loss and is mainly distributed among the zeroth-order transmission 240, the zeroth-order reflection 250, and the less-efficient (or “secondary”) first-order diffraction (related to either the transmission 220 or the reflection 230). Embodiments of the present invention utilize the secondary first-order diffraction for power and/or spectral monitoring within the WBC resonator. The secondary first-order diffraction is wavelength-combined, like the primary first-order diffraction beam, and thus perfectly indicates power fluctuations and the dynamics of spectral composition of the WBC resonator output.

[0054] FIG. 3 depicts a WBC resonator 300 in accordance with various embodiments of the invention. In the WBC resonator 300, multiple emitters 305 emit laser beams represented in FIG. 3 by chief rays 310. Although FIG. 3 depicts the use of four emitters 305, embodiments of the invention feature two, three, or more than four emitters 305. The chief rays 310 are overlapped at or proximate a diffraction grating 315 (or other dispersive element) by transform optics 320. In various embodiments of the invention, transform optics 320 include, consist essentially of, or consist of one or more cylindrical and/or spherical lenses and/or one or more other optical elements. A partially reflective output coupler 325 provides feedback to the emitters 305 of the WBC resonator 300 to lock the emitter wavelengths (which are each typically unique, i.e., different from each other) so that all of the first-order diffractions are combined into a first-order transmission beam 330 and a first-order reflection beam 335. In the exemplary embodiment illustrated in FIG. 3, grating 315 is a transmissive diffraction grating, and thus the output coupler 325 is positioned on the transmission side (i.e., the side opposite the emitters 305) to receive the first-order transmission beam 330 from the grating 315. Thus, in the illustrated embodiment, the first-order reflection 335 is the secondary beam used for power and/or spectral monitoring.

[0055] In various embodiments of the invention, the WBC resonator may include an optical system 340 located downstream of the grating 315 (e.g., between the grating 315 and the output coupler 325) for beam resizing and/or mitigation of cross-coupling. For example, the optical system 340 may include, consist essentially of, or consist of one or more lenses and/or any of the components utilized for cross-coupling mitigation and described in U.S. patent application Ser. No. 14/964,700, filed on Dec. 10, 2015, the entire disclosure of which is incorporated by reference herein.

[0056] As shown, the WBC resonator 300 also includes a power detector 345 that receives all or a portion of the first-order reflection 335 and is utilized to monitor WBC power fluctuations based thereon. The power detector 345 may include, consist essentially of, or consist of, for example, one or more photodiodes and/or one or more thermopiles. In various embodiments of the invention, the WBC resonator 300 also includes an optical system 350 in the optical path from the grating 315 to the detector 345. The optical system 350 may include optics for beam redirection, imaging, focusing, and/or power attenuation, and/or components (e.g., one or more slits) for blocking stray light or other beams such as the zeroth-order transmission beam 355 and the zeroth-order reflection beam 360 from reaching the detector 345.

[0057] In various embodiments, the detector 345 is coupled to a control system (or “controller”) 365 that controls one or more components and/or functions of the WBC resonator 300 based on the detected power. For example, the controller 365 may automatically shut off power supplied to the system (e.g., to the emitters 305) in the event of a fluctuation or diminishment of the power level detected by detector 345. In other embodiments, the controller 365 may block propagation of the combined multi-wavelength beam 330 transmitted by the output coupler 325 (e.g., to an optical fiber or to a workpiece to be processed) in the event of power fluctuations, e.g., during initial stages of operation of the WBC resonator 300, where power fluctuations may occur as various components heat up. For example, the controller 365 may be configured to block the propagation of beam 330 via operation of a shutter, a mirror, or other occlusion or redirection mechanism that prevents the beam 330 from exiting the resonator 300 from its beam exit. In various embodiments, the controller 365 may be configured to block propagation of beam 330 and/or shut off power to system 300 in the event of power fluctuations that exceed ±20% of a typical or desired output power level, ±10% of the typical or desired output power level, or ±5% of the typical or desired output power level.

[0058] In various embodiments, the controller 365 may adjust the diffraction grating 315 (e.g., a tilt angle of the grating) and/or the transform optics 320 (e.g., a position and/or angle of one or more lenses or mirrors) in response to the detected power level. For example, the WBC resonator 300 may include one or more positioning systems that are responsive to commands from the controller 365 and that control the position (e.g., tilt angle, location, etc.) of components such as the grating 315 and the transform optics 320. In various embodiments, the positioning system may include, consist essentially of, or consist of, e.g., tip/tilt mounts with one or more actuators.

[0059] In various embodiments, the controller 365 utilizes the monitored power level as feedback to stabilize the WBC output beam via control of the power or current supplied to the emitters 305, for example, via control of a power supply 370 supplying power to the emitters 305, That is, the controller 365 may increase the power or current supplied to the emitters 305 if the sensed output power decreases and vice versa. In various embodiments, the controller 365 may monitor the output power and, in the event of the output power gradually diminishing, the controller 365 may utilize the sensed output power as feedback to predict the operational lifetime of the system. For example, the controller 365 may forecast when the decreasing output power of the system (or, similarly, the increasing power supplied to the emitters 305 to counteract the decreased output power) will reach a level outside of the specified operating power range for the system (e.g., exceed or fall below a predetermined threshold power level) and predict the lifetime of the system 300 based on the power forecast and the service time of the system (e.g., based on one or more of total usage time, usage patterns, etc.).

[0060] The controller 365 may be provided as either software, hardware, or some combination thereof. For example, the system may be implemented on one or more conventional server-class computers, such as a PC having a CPU board containing one or more processors such as the Pentium or Celeron family of processors manufactured by Intel Corporation of Santa Clara, Calif., the 680×0 and POWER PC family of processors manufactured by Motorola Corporation of Schaumburg, Ill., and/or the ATHLON line of processors manufactured by Advanced Micro Devices, Inc., of Sunnyvale, Calif. The processor may also include a main memory unit for storing programs and/or data relating to the methods described herein. The memory may include random access memory (RAM), read only memory (ROM), and/or FLASH memory residing on commonly available hardware such as one or more application specific integrated circuits (ASIC), field programmable gate arrays (FPGA), electrically erasable programmable read-only, memories (EEPROM), programmable read-only memories (PROM), programmable logic devices (PLD), or read-only memory devices (ROM). In some embodiments, the programs may be provided using external RAM and/or ROM such as optical disks, magnetic disks, as well as other commonly used storage devices. For embodiments in which the functions are provided as one or more software programs, the programs may be written in any of a number of high level languages such as PYTHON, FORTRAN, PASCAL, JAVA, C, C++, C#, BASIC, various scripting languages, and/or HTML. Additionally, the software may be implemented in an assembly language directed to the microprocessor resident on a target computer; for example, the software may be implemented in Intel 80×86 assembly language if it is configured to run on an IBM PC or PC clone. The software may be embodied on an article of manufacture including, but not limited to, a floppy disk, a jump drive, a hard disk, an optical disk, a magnetic tape, a PROM, an EPROM, EEPROM, field-programmable gate array, or CD-ROM.

[0061] In various embodiments of the invention, spectral information from the secondary diffracted beam in the WBC resonator may be monitored in addition to or instead of power. FIG. 4 depicts a WBC resonator 400 in which the secondary diffracted beam, corresponding in the illustrated embodiment to the first-order reflection 335, is utilized to monitor both power and spectral information of the main diffracted beam (i.e., first-order transmission 330). In FIG. 4, the secondary beam 335 propagates to a fiber coupler 405 (illustrated as a 1×2 fiber coupler), or other beam-splitter, which divides the beam such that a portion of the beam is received by the power detector 345, and a second portion of the beam is received by a spectrometer 410. As in resonator 300 of FIG. 3, the controller 365 may be coupled to the power detector 345, and the controller 365 may also be coupled to the spectrometer 410, such that the detected power and spectral information may be utilized by the controller as input to control various functionality and/or components of the WBC resonator 400. Since the emitters 305 for the resonator each may emit at a different wavelength, the spectral information from the spectrometer 410 may be utilized to monitor and/or control individual emitters 305. For example, if a particular portion of the spectrum detected by the spectrometer 410 exhibits a power level that is too high or too low, the controller 365 may utilize the spectral information to modulate the operating power of an individual emitter 305 or group of emitters. In various embodiments of the invention, the monitored spectral information may be utilized to differentiate power fluctuations or drops due to overall degradations of the system 400 from failures of particular emitters 305 or emitter groups. For example, if failure or performance diminishment is detected of particular emitters 305, the controller 365 may alert the operator and/or shut down power to the system so that the particular emitters may be replaced.

[0062] The exemplary embodiments shown in FIGS. 3 and 4 also illustrate the zeroth-order transmission beam 355 and zeroth-order reflected beam 360 produced by the diffraction at the grating 315. In various embodiments, these beams may not be ideal for WBC power and spectral monitoring, because they are independent of the WBC resonator. That is, alterations of power within these beams may not be directly correlated with fluctuations of the main WBC beam and the WBC output power. However, in various embodiments, one or more of the zeroth-order beams 355, 360 are used to monitor emitter power (i.e., emitter power incident on the grating 315), which is not affected by the WBC resonator. For example, resonator misalignment (e.g., misalignment, blockage, or even removal of the output coupler 325) will typically decrease WBC output power and thus the signal detected by power detector 345, but such misalignment will typically not reduce the power level of the zeroth-order beams. Therefore, in various embodiments, one or more of the zeroth-order beams 355, 360 (i.e., reflection and/or transmission) may also be monitored (e.g., via a dedicated power detector and/or spectrometer) for a more complete picture of power variations and the possible causes. For example, differences in power and/or spectral information detected via monitoring of the zeroth-order beams may be used in combination with such differences detected using the secondary first-order beam in order to diagnose the root cause(s) of the fluctuations. In an example embodiment, the controller 365 may modulate the power supplied to (and thus output from) one or more of the emitters 305 based on a signal (e.g., power and/or spectral information) received from one or more of the zeroth-order beams 355, 360, and the controller 365 may also adjust the position (e.g., location and/or tilt) of one or more other components (e.g., the grating 315, transform optics 320, coupler 325, etc.) based on a signal (e.g., power and/or spectral information) received from the secondary beam 335.

[0063] The example WBC resonators 300, 400 depicted in FIGS. 3 and 4 utilize the diffraction grating 315 configured at an angle not corresponding to the Littrow configuration discussed above in relation to FIG. 2. That is, the angle of incidence with respect to the grating (i.e., angle a in FIG. 2) is not equal to the first-order diffraction angle (i.e., angle b in FIG. 2) in order to spatially separate the secondary first-order reflected beam 335 from the incident beam 310. While this off-Littrow configuration facilitates the capture of the secondary diffracted beam without interference with or from the incident beam, the off-Littrow configuration may result in lower grating efficiency and thus lower output power of the WBC resonator.

[0064] Embodiments of the invention address this potential inefficiency by tilting the diffraction grating away from the Littrow configuration in the non-WBC direction (or “dimension”) while maintaining the grating in the Littrow configuration within the WBC plane. This embodiment of the invention is depicted in FIGS. 5A and 5B, in which the secondary beam (first-order reflection 335) is spatially separated from the incident beam 310 in the non-WBC direction (but not in the WBC direction), facilitating the monitoring of the secondary beam by the power detector 345 (and/or the spectrometer 410, not shown in FIGS. 5A and 5B).

[0065] As shown in the top view of resonator 500 in FIG. 5A, the diffraction grating 510 is configured at the Littrow angle in the WBC plane. Therefore, the first-order reflection 335, i.e., the secondary beam utilized for monitoring, propagates back toward the beam source (i.e., the emitters 305) when viewed in the WBC plane. As shown in the side view of FIG. 5B, the grating 510 is tilted by an angled in the non-WBC plane, which introduces a “walk-off angle” equal to 2d for the first-order reflection 335 relative to the incident beam 310, thereby enabling the first-order reflection 335 to be more easily propagated to the power detector 345 (and/or spectrometer 410, not shown in FIGS. 5A and 5B). In various embodiments, the grating angle d in the non-WBC plane is relatively small in order to minimize or substantially eliminate possible deleterious side effects such as aberration and/or beam twist. For example, in various embodiments the angle d is less than 5°, less than 3°, less than 2°, or even less than 1°. In various embodiments, the angle d may be at least 0.001°, at least 0.005°, at least 0.01°, at least 0.05°, at least 0.1°, or even at least 0.5°. In typical embodiments, the angled grating as depicted in FIGS. 5A and 5B has little or no effect on the power and direction of the zeroth-order beams 355, 360.

[0066] As utilized herein, the “WBC plane” corresponds to the plane in which input beams are spectrally combined in a WBC resonator in accordance with embodiments of the present invention. In addition, a “non-WBC plane” is a plane different from the WBC plane, e.g., a plane substantially perpendicular to the WBC plane.

[0067] In various embodiments of the invention, the layout depicted in FIGS. 5A and 5B may be utilized for a WBC resonator incorporating a reflective diffraction grating. In such embodiments, the positions of the output coupler 325 and optical system 340 are exchanged with those of the power detector 345 and optical system 350, respectively, because the first-order reflection 335 is utilized as the main output beam of the WBC resonator, while the first-order transmission 330 is utilized for power and/or spectral monitoring.

[0068] Laser systems in accordance with embodiments of the present invention may utilize the primary diffracted beam 335 for processing of a workpiece and/or may couple the primary beam 335 into an optical fiber. The controller 365 may, in accordance with the embodiments of the invention, control the power and/or spectrum of the beam 335 based on information received from detector 345 and/or spectrometer 410 (as detailed above), and also based on the type of desired processing (e.g., cutting, welding, etc.) and/or on one or more characteristics (e.g., materials parameters, thickness, material type, etc.) of the workpiece to be processed (or being processed) and/or of a desired processing path mapped out for the output beam 335. Such process and/or material parameters may be selected by a user from a stored database in a memory associated with controller 365 or may be entered via an input device (e.g., touchscreen, keyboard, pointing device such as a computer mouse, etc.). One or more processing paths may be provided by a user and stored in an onboard or remote memory associated with controller 365. After workpiece and/or processing path selection, the controller 365 queries the database to obtain the corresponding parameter values. The stored values may include an output power or output-beam spectrum suitable to the material and/or to one or more processing paths or processing locations on the material.

[0069] The controller 365 may, in some embodiments, receive feedback regarding the position and/or processing efficacy of the beam relative to the workpiece from a feedback unit connected to suitable monitoring sensors. In response to signals from the feedback unit, the controller 365 may alter the power and/or spectrum of the beam as detailed herein. Embodiments of the invention may also incorporate aspects of the apparatus and techniques disclosed in U.S. patent application Ser. No. 14/639,401, filed on Mar. 5, 2015, U.S. patent application Ser. No. 15/261,096, filed on Sep. 9, 2016, and U.S. patent application Ser. No. 15/649,841, filed on Jul. 14, 2017, the entire disclosure of each of which is incorporated by reference herein.

[0070] In addition, the laser systems in accordance with embodiments of the invention may incorporate one or more systems for detecting the thickness of the workpiece and/or heights of features thereon. For example, the laser system may incorporate systems (or components thereof) for interferometric depth measurement of the workpiece, as detailed in U.S. patent application Ser. No. 14/676,070, filed on Apr. 1, 2015, the entire disclosure of which is incorporated by reference herein. Such depth or thickness information may be utilized by the controller to control the beam power and/or spectrum to optimize the processing (e.g., cutting or welding) of the workpiece, e.g., in accordance with records in the database corresponding to the type of material being processed.

[0071] The terms and expressions employed herein are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.