Laser processing device, method of operating same, and method of using same to process a workpiece

Abstract

To provide a laser-processing apparatus and its components, and methods for operating the same.SOLUTION: A laser-processing apparatus comprises a positioner arranged within a beam path along which a laser energy beam can be propagated. A controller may be used to control the operation of the positioner to deflect the beam path within a first primary angular range and a second primary angular range and to deflect the beam path to a plurality of angles within each of the first primary angular range and the second primary angular range. An integrated beam dump system includes a frame, and a pickoff mirror and beam dump coupled to the frame.SELECTED DRAWING: Figure 1

Description

Related Applications

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 799,218, filed January 31, 2019, U.S. Provisional Patent Application No. 62 / 832,064, filed April 10, 2019, and U.S. Provisional Patent Application No. 62 / 854,579, filed May 30, 2019, each of which is incorporated by reference in its entirety. BACKGROUND

[0002] I.Technical field FIELD OF THE INVENTION The embodiments described herein relate generally to laser processing devices and components thereof, and to methods for operating the same.

[0003] II.Technical background Generally, laser processing of a workpiece is accomplished by applying laser energy to the workpiece to heat, melt, vaporize, ablate, crack, bleach, abrade, roughen, carbonize, foam, or otherwise modify one or more properties or characteristics of one or more materials forming the workpiece. For example, a workpiece, such as a printed circuit board (PCB), can be laser processed to form vias therein. Rapid workpiece processing may require the use of a high-power laser source to generate the laser energy, rapid variation of the workpiece location where the laser energy is applied, and rapid variation of the laser energy characteristics (e.g., pulse duration, pulse energy, pulse repetition rate, etc.). Additionally, the wavelength of the laser energy used during laser processing may be selected depending on the type of workpiece being processed. However, conventional components and methods developed for laser processing using laser energy in one particular wavelength range (e.g., wavelengths in the ultraviolet region of the electromagnetic spectrum) may not be suitable for performing the same laser processing using laser energy in another wavelength range (e.g., wavelengths in the long-wave infrared region of the electromagnetic spectrum). The embodiments described herein were developed with these and other problems discovered by the inventors in mind.

[0004] One embodiment of the present invention can be characterized as a laser processing apparatus including a laser source capable of generating a beam of laser energy propagated along a beam path, a first positioner disposed within the beam path and capable of deflecting the beam path, and a controller coupled to the first positioner. The controller may be configured to control operation of the first positioner to deflect the beam path within a first primary angular range and a second primary angular range. The second primary angular range does not overlap with and does not border the first primary angular range. The controller may be further configured to control operation of the first positioner to deflect the beam path to a plurality of first angles within the first primary angular range and a plurality of second angles within the second primary angular range.

[0005] Another embodiment of the present invention can be characterized as an integrated beam dump system including a frame, a pick-off mirror coupled to the frame and configured to reflect a laser energy beam, and a beam dump coupled to the frame and configured to absorb the laser energy beam.

[0006] Another embodiment of the present invention can be characterized as an integrated beam dump system comprising a frame having a first surface and at least one second surface, wherein the first surface can be configured to reflect a laser energy beam, and the at least one second surface can be configured to absorb the laser energy beam.

[0007] Another embodiment of the invention can be characterized as a wavefront correcting optic comprising a mirror having a reflective surface, the shape of the reflective surface being characterized by fringe Zernike Z4 and Z9 terms, the ratio of the coefficient of the Z9 term to the coefficient of the Z4 term being in the range of −0.1 to −0.3.

[0008] Another embodiment of the present invention can be characterized as a wavefront correction optical component including a deformable mirror having a reflective surface, a body, and a pocket defined within the body. The body can include a deformable membrane region between the reflective surface and the pocket. A central portion of the membrane region can have a first thickness and a peripheral portion of the membrane region can have a second thickness greater than the first thickness.

[0009] Another embodiment of the present invention can be characterized as a wavefront correction optical component including a deformable mirror having a reflective surface, a body including at least one rib, and a plurality of pockets defined within the body. The body can include a deformable membrane region between the reflective surface and the pocket. The at least one rib can be disposed between the plurality of pockets.

[0010] Another embodiment of the present invention can be characterized as a wavefront correction optical component system comprising: a membrane-type deformable mirror having a pressurizable pocket; a base coupled to the mirror, the base having at least one perforation extending therethrough, the at least one perforation being in fluid communication with the pressurizable pocket; and a mount plate coupled to the base and an optical mount assembly.

[0011] Another embodiment of the present invention can be characterized as a system including a first optical component transmissive to a laser energy beam, the first optical component being susceptible to thermal lensing, a wavefront compensation optic configured to compensate for wavefront aberrations in the laser energy beam transmitted through the first optical component due to the thermal lensing effect, and an optical relay system positioned and configured to relay an image of the first optical component at a first plane to a second plane. The wavefront compensation optic can be positioned at the second plane. The first optical relay system can be configured such that the size of the image of the first optical component at the second plane is different from the size of the image of the first optical component at the first plane.

[0012] Another embodiment of the present invention can be characterized as a system including an acousto-optic deflector (AOD), a dispersion compensator including at least one selected from the group consisting of a prism and a grating, a first optical component optically coupled to the dispersion compensator at a position optically upstream of the dispersion compensator, the first optical component configured to expand an incident laser energy beam, and a second optical component optically coupled to the dispersion compensator and the AOD at a position optically between the dispersion compensator and the AOD, the second optical component configured to reduce the incident laser energy beam.

[0013] Another embodiment of the present invention can be characterized as a system including: an acousto-optic deflector (AOD) capable of diffracting an incident laser energy beam and outputting the diffracted laser energy beam along a beam path, the AOD being capable of deflecting the beam path within a first angular range and a second angular range by variably diffracting the incident laser energy beam; a first dispersion compensator comprising at least one selected from the group consisting of a prism and a grating, the first dispersion compensator being optically coupled to the output of the AOD and positioned on the beam path deflected within the first angular range; and a second dispersion compensator comprising at least one selected from the group consisting of a prism and a grating, the second dispersion compensator being optically coupled to the output of the AOD and positioned on the beam path deflected within the second angular range.

[0014] Another embodiment of the present invention can be characterized as a system including a laser source capable of generating a laser energy beam propagated along a beam path; a positioner disposed within the beam path and capable of deflecting the beam path; the positioner including a first acousto-optic deflector (AOD) and a second AOD optically coupled to an output of the first AOD; and a controller coupled to the positioner, the controller configured to operate the first AOD and the second AOD to temporally divide the laser energy beam into at least one pulse slice during at least one slice period. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram of a multi-head laser processing device according to an embodiment. [Figure 2-3] 2 and 3 show schematic diagrams of beam path deflection schemes that can be implemented using the first positioner according to certain embodiments. [Figure 4] FIG. 4 is a schematic diagram of a multi-axis AOD system that may be incorporated into the first positioner according to one embodiment. [Figure 5-6] 5 and 6 show schematic diagrams of how a beam dump system according to an embodiment can be incorporated into the first positioner. [Figure 7] 7 is a perspective view of an integrated beam dump system according to one embodiment in an arbitrary u / v / w coordinate system, in which the u-axis, v-axis, and w-axis are orthogonal to one another. [Figure 8-9] 8 and 9 are perspective views illustrating exemplary beam paths along which laser energy can propagate and be trapped within the integrated beam dump system shown in FIG. [Figure 10] 10 is a perspective view of an integrated beam dump system according to another embodiment in an arbitrary u / v / w coordinate system, in which the u-axis, v-axis, and w-axis are orthogonal to one another. [Figure 11-14] 11-14 are perspective views illustrating exemplary beam paths along which laser energy can propagate and be trapped within the integrated beam dump system shown in FIG. [Figure 15] FIG. 15 shows a graph illustrating the experimentally determined dependence of the coefficients of the Z4 and Z9 terms (and their ratio) of the fringe Zernike polynomials on the temperature of a bulk transparent material. [Figure 16] FIG. 16 is a schematic plan view of a wavefront compensation optical component according to an embodiment. [Figure 16A] FIG. 16A is a schematic cross-sectional view of the wavefront compensation optical component shown in FIG. 16 taken along line XVIA-XVIA in FIG. [Figure 17] FIG. 17 is a schematic cross-sectional view of the wavefront compensation optic shown in FIG. 16 coupled to a base according to one embodiment. [Figure 18-19] 18 and 19 are schematic cross-sectional views of wavefront compensation optical components according to other embodiments, each connected to a base. [Figure 20-24] 20, 21, 22, 23, and 24 illustrate an optical relay system according to an embodiment. [Figure 25] FIG. 25 illustrates an optical mount according to one embodiment. [Figure 26-29] 26, 27, 28, and 29 are schematic illustrations of beam path assemblies incorporating dispersion compensators according to certain embodiments. [Figure 30] FIG. 30 is a schematic diagram of a beam path assembly for directing a beam path from a laser source to the first and second optical ports shown in FIG. 29 according to one embodiment. [Figure 31-34] 31, 32, 33, and 34 show graphs illustrating exemplary frequency ranges over which the first and second AODs of the first positioner can be driven, according to some embodiments. [Figure 35-41] 35, 35A, 35B, 36, 37, 38, 39, 40, and 41 schematically illustrate an approach for performing pulse slicing according to one embodiment. Detailed Description

[0016] Examples of embodiments will now be described with reference to the accompanying drawings. Unless explicitly stated, in the drawings, the sizes, positions, etc. of components, features, elements, etc., and the distances therebetween, are not necessarily to scale and have been exaggerated for clarity. Like numbers refer to like elements throughout the drawings. Thus, the same or similar numbers may be described with reference to other drawings even if they are not mentioned or described in the corresponding drawing. Also, elements without reference numbers may be described with reference to other drawings.

[0017] The terminology used in the specification is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. As used herein, the singular is intended to include the plural unless the content clearly dictates otherwise. Furthermore, it should be understood that the terms "comprises" and / or "comprising," when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Unless otherwise indicated, when a range of values ​​is recited, the range includes the upper and lower limits, as well as any subranges between the upper and lower limits of the range. Unless otherwise indicated, terms such as "first" and "second" are used merely to distinguish elements from one another. For example, one node can be referred to as a "first node," and similarly, another node can be referred to as a "second node," or vice versa.

[0018] Unless otherwise indicated, "about," "around," and the like mean that amounts, sizes, compositions, parameters, and other quantities and characteristics are not, and need not be, exact, but may be approximate and / or larger or smaller, as appropriate, or to reflect tolerances, conversion factors, rounding, measurement error, and the like, as well as other factors known to those skilled in the art. Spatially relative terms such as "below," "down," "lower," "upper," and "upper" may be used herein for ease of description when describing the relationship of an element or feature to another element or feature, as shown in the figures. It should be understood that spatially relative terms are intended to encompass different orientations in addition to those depicted in the figures. For example, an element described as being "below" or "below" another element or feature would be oriented "above" that other element or feature if the object in the figure were inverted. Thus, the exemplary term "below" can encompass both an orientation of above and below. If the object is oriented in other ways (e.g., rotated 90 degrees or at other orientations), the spatially relative descriptors used herein may be interpreted accordingly.

[0019] The section headings used herein, unless specifically stated, are for organizational purposes only and should not be construed as limiting the subject matter described. It will be understood that many different forms, embodiments, and combinations are possible without departing from the spirit and teachings of the present disclosure, and that the present disclosure should not be construed as limited to the example embodiments set forth herein. Rather, these examples and embodiments are provided so that this disclosure will be complete and all-inclusive, and will fully convey the scope of the disclosure to those skilled in the art.

[0020] I. Overview Embodiments described herein generally relate to methods and apparatus for laser processing (or, more simply, "processing") a workpiece. Processing is generally accomplished in whole or in part by applying laser radiation to the workpiece to heat, melt, vaporize, ablate, scratch, bleach, polish, roughen, carbonize, foam, or otherwise modify one or more characteristics or properties (e.g., chemical composition, atomic structure, ionic structure, molecular structure, electronic structure, microstructure, nanostructure, density, viscosity, refractive index, magnetic permeability, dielectric constant, texture, color, hardness, transmissivity to electromagnetic radiation, etc., or any combination thereof) of one or more materials forming the workpiece. The material being processed may be external to the workpiece before or during processing, or may be located entirely within the workpiece (i.e., not external to the workpiece) before or during processing.

[0021] Specific examples of processes that can be performed with the disclosed laser processing apparatus include via drilling or other hole formation, cutting, punching, welding, scribing, engraving, marking (e.g., surface marking, subsurface marking, etc.), laser-induced forward transfer, cleaning, bleaching, bright pixel repair (e.g., color filter darkening, OLED material modification, etc.), film removal, surface texturing (e.g., roughening, smoothing, etc.), or the like, or any combination thereof. Thus, one or more features that may be formed on or in a workpiece as a result of processing may include openings, slots, vias or other holes, grooves, trenches, scribe lines, kerfs, recesses, conductive traces, ohmic contacts, resistor patterns, human-readable or machine-readable indicia (e.g., comprising one or more areas in or on the workpiece having one or more visually or texturally distinct characteristics), or the like, or any combination thereof. Apertures, slots, vias, holes, and other features may have any suitable or desirable shape when viewed from above (e.g., circular, oval, square, rectangular, triangular, tubular, or the like, or any combination thereof). Furthermore, apertures, slots, vias, holes, and other features may extend completely through the workpiece (e.g., to form so-called "through vias," "through holes," etc.) or may extend only partially through the workpiece (e.g., to form so-called "blind vias," "blind holes," etc.).

[0022] The workpieces that can be machined can be generally characterized as being formed from one or more metals, polymers, ceramics, composites, or any combination thereof (e.g., whether alloys, compounds, mixtures, solutions, composites, etc.). Thus, materials that may be processed include one or more metals such as Al, Ag, Au, Cr, Cu, Fe, In, Mg, Mo, Ni, Pt, Sn, Ti, and the like, or any combination thereof (e.g., whether alloyed, composite, etc.), conductive metal oxides (e.g., ITO, etc.), transparent conductive polymers, ceramics, waxes, resins, interlayer dielectric materials (e.g., silicon oxide, silicon nitride, silicon oxynitride, etc., low-k dielectric materials such as methyl silsesquioxane (MSQ), hydrogen silsesquioxane (HSQ), fluorotetraethyl orthosilicate (FTEOS), etc., or any combination thereof), organic dielectric materials (e.g., SILK, benzocyclobutene, Nautilus (all manufactured by Dow), polyfluorotetraethylene (manufactured by DuPont), FLARE (Allied or any combination thereof), semiconductor or optical element substrate materials (e.g., Al2O3, AlN, BeO, Cu, GaAS, GaN, Ge, InP, Si, SiO2, SiC, Si 1-x Ge x(0.0001 < x < 0.9999), or any combination thereof or an alloy), glass (e.g., fused quartz, soda-lime glass, sodium borosilicate glass, lead oxide glass, aluminosilicate glass, germanium oxide glass, aluminate glass, phosphate glass, borate glass, chalcogenide glass, amorphous metal, etc., or any combination thereof), sapphire, polymeric materials (e.g., polyamide, polyimide, polyester, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyacetal, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, polyphenylene sulfide, polyethersulfone, polyetherimide, polyetheretherketone, liquid crystal polymer, acrylonitrile butadiene styrene, or any compound, composite, or alloy thereof), leather, paper, assembled materials (e.g., Ajinomoto build-up film also known as "ABF"), solder resist, etc., or any composite, laminate, or other combination thereof is included.

[0023] Specific examples of workpieces that may be processed include printed circuit board (PCB) panels (also referred to herein as "PCB panels"), PCBs, PCB laminates (e.g., FR4, high Tg epoxy, BT, polyimide, etc., or any combination thereof), PCB laminate prepregs, substrate-like PCBs (SLPs), flexible printed circuit (FPC) panels (also referred to herein as "FPC panels"), FPCs, coverlay films, integrated circuits (ICs), IC substrates, IC packages (ICPs), light emitting diodes (LEDs), LED packages, semiconductor wafers, electronic or optical device substrates, interposers, lead frames, lead frame blanks, display substrates (e.g., TFTs, color filters, , organic light emitting diode (OLED) arrays, quantum dot LED arrays, etc., or any combination thereof), lenses, mirrors, turbine blades, powders, films, foils, plates, molds (e.g., wax molds, molds for injection molding or investment casting processes, etc.), textiles (woven fabrics, felt, etc.), surgical instruments, medical implants, packaged products, shoes, bicycles, automobiles, automobile or aviation parts (e.g., frames, body panels, etc.), appliances (e.g., microwave ovens, ovens, refrigerators, etc.), device housings (e.g., for watches, computers, smartphones, tablet computers, wearable electronic devices, etc., or any combination thereof).

[0024] II. System Overview FIG. 1 is a schematic diagram of a laser processing device according to one embodiment of the present invention.

[0025] Referring to the embodiment shown in FIG. 1, a laser processing apparatus 100 (also referred to herein simply as an “apparatus”) for processing workpieces 102a and 102b (each collectively referred to as “workpiece 102”) can be characterized as including a laser source 104 that generates a laser energy beam, a first positioner 106, a plurality of second positioners (e.g., second positioners 108a and 108b, each collectively referred to as “second positioners 108”), a third positioner 110, and a plurality of scan lenses (e.g., scan lenses 112a and 112b, each collectively referred to as “scan lenses 112”). Although FIG. 1 illustrates an embodiment in which the laser processing apparatus 100 includes two second positioners 108, it will be understood that many of the embodiments disclosed herein may also be applied to laser processing apparatuses that include only one second positioner 108, or may also be applied to laser processing apparatuses that include more than two second positioners 108.

[0026] The scan lens 112 and the corresponding second positioner 108 may be integrated into a common housing or "scan head," if desired. For example, the scan lens 112a and the corresponding second positioner 108 (i.e., second positioner 108a) may be integrated into a common scan head 120a. Similarly, the scan lens 112b and the corresponding second positioner 108 (i.e., second positioner 108b) may be integrated into a common scan head 120b. As used herein, each of the scan heads 120a and 120b may also be collectively referred to herein as the "scan head 120."

[0027] 1 shows one third positioner 110 commonly supporting multiple workpieces 102, it will be appreciated that multiple third positioners 110 may be provided (e.g., for supporting different workpieces 102, for supporting a common workpiece 102, or for similar purposes, or any combination thereof). However, in light of the description below, it should be understood that the inclusion of any second positioner 108 or third positioner 110 is optional if the functionality provided by any second positioner 108 or third positioner 110 is not required.

[0028] As described in more detail below, the first positioner 106 is capable of diffracting, reflecting, refracting, or deflecting the laser energy beam to deflect the beam path 114 to one of the second positioners 108. As used herein, the term "beam path" refers to the path traversed by laser energy in the laser energy beam as it propagates from the laser source 104 to the scan lens 112. When deflecting the beam path 114 to the second positioner 108a, the beam path 114 can be deflected by any angle (e.g., measured relative to the beam path 114 entering the first positioner 106) within a first angular range (also referred to herein as a "first primary angular range 116a"). Similarly, when deflecting the beam path 114 to the second positioner 108b, the beam path 114 can be deflected at any angle (e.g., measured relative to the beam path 114 entering the first positioner 106) within a second angular range (also referred to herein as the “second primary angular range 116b”). As used herein, each of the first primary angular range 116a and the second primary angular range 116b is also referred to herein collectively as the “primary angular range 116.” Generally, the first primary angular range 116a does not overlap or border the second primary angular range 116b. The first primary angular range 116a may be greater than, less than, or equal to the second primary angular range 116b. As used herein, deflecting the beam path 114 within one or more primary angular ranges 116 is referred to herein as "beam divergence."

[0029] Each of the second positioners 108 is capable of diffracting, reflecting, refracting, or the like, or any combination thereof, the laser energy beam generated by the laser source 104 and deflected by the first positioner 106 (i.e., "deflecting" the laser energy beam), so as to deflect the beam path 114 to a corresponding scan lens 112. For example, second positioner 108a can deflect beam path 114 to scan lens 112a. Similarly, second positioner 108b can deflect beam path 114 to scan lens 112b. When deflecting beam path 114 to scan lens 112a, second positioner 108a can deflect beam path 114 at any angle (e.g., measured relative to the optical axis of scan lens 112a) within a first angular range (also referred to herein as “first secondary angular range 118a”). Similarly, when deflecting beam path 114 to scan lens 112b, second positioner 108b can deflect beam path 114 at any angle (e.g., measured relative to the optical axis of scan lens 112b) within a second angular range (also referred to herein as “second secondary angular range 118b”). First secondary angular range 118a can be greater than, less than, or equal to second secondary angular range 118b.

[0030] Laser energy deflected onto scan lens 112 is typically focused by scan lens 112 to impinge on workpiece 102 and transmitted to propagate along the beam axis. For example, laser energy deflected onto scan lens 112a impinges on workpiece 102a, while laser energy deflected onto scan lens 112b impinges on workpiece 102b. The laser energy impinging on workpiece 102 can be characterized as having a Gaussian spatial intensity profile or a non-Gaussian (i.e., "shaped") spatial intensity profile (e.g., a "top hat" spatial intensity profile, a super-Gaussian spatial intensity profile, etc.).

[0031] 1 depicts multiple workpieces 102 positioned such that each workpiece intersects a different beam axis, it will be appreciated that a single larger workpiece 102 may be machined with laser energy irradiated from multiple scan lenses. Additionally, while FIG. 1 depicts multiple scan lenses 112 positioned such that each scan lens 112 transmits laser energy propagating along a beam path deflected by a different second positioner 108, it will be appreciated that apparatus 100 may be configured such that laser energy propagating along a beam path deflected by multiple second positioners 108 transmits through a common scan lens 112 (e.g., using mirrors, prisms, beam splitters, etc., or any combination thereof).

[0032] As used herein, the term "spot size" refers to the diameter or maximum spatial width of the laser energy beam impinging on a location where the beam axis intersects an area of ​​the workpiece 102 that is at least partially processed by the impinging laser energy beam (also referred to as a "process spot," "spot location," or simply "spot"). For purposes of this description, spot size refers to the distance from the beam axis where the optical intensity is 1 / e of the optical intensity at the beam axis. 2The spot size of the laser energy beam is measured as the radial or transverse distance down to the beam waist. Generally, the spot size of the laser energy beam is smallest at the beam waist. When irradiated onto the workpiece 102, the laser energy in the beam can be characterized as striking the workpiece 102 with a spot size ranging from 2 μm to 200 μm. However, it will be understood that the spot size can be less than 2 μm or greater than 200 μm. Thus, the laser energy beam irradiated onto the workpiece 102 can have a spot size greater than, less than, or equal to 2 μm, 3 μm, 5 μm, 7 μm, 10 μm, 15 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 80 μm, 100 μm, 150 μm, 200 μm, etc., or any value between these values.

[0033] The apparatus 100 may also include one or more other optical components (e.g., beam traps, beam expanders, beam shapers, beam splitters, apertures, filters, collimators, lenses, mirrors, prisms, polarizers, phase retarders, diffractive optical elements (commonly known in the art as DOEs), refractive optical elements (commonly known in the art as ROEs), etc., or any combination thereof) to focus, expand, collimate, shape, polarize, filter, split, combine, crop, absorb, or otherwise modify, condition, etc., the laser energy beam as it propagates along the beam path 114. To the extent that optical components such as beam expanders, lenses, beam splitters, prisms, dichroic filters, windows, wave plates, DOEs, ROEs, etc. are constructed from a collection of transparent materials (which may be coated with anti-reflective coatings, etc., as needed) intended to transmit an incident laser energy beam, such optical components are collectively referred to herein as "transmissive optical components." As used herein, a collection of positioners and other optical components, when assembled together in laser processing apparatus 100, are considered to comprise a "beam path assembly."

[0034] A. Laser Source In one embodiment, the laser source 104 is capable of generating laser pulses. As such, the laser source 104 may include a pulsed laser source, a CW laser source, a QCW laser source, a burst-mode laser, or the like, or any combination thereof. If the laser source 104 includes a QCW or CW laser source, the laser source 104 may operate in a pulsed mode or may operate in a non-pulsed mode and may further include a pulse gating unit (e.g., an acousto-optic (AO) modulator (AOM), a beam chopper, etc.) that temporally modulates the beam of laser radiation output from the QCW or CW laser source. Although not shown, the apparatus 100 may optionally include one or more harmonic generation crystals (also known as “wavelength conversion crystals”) configured to convert the wavelength of the light output by the laser source 104. However, in other embodiments, the laser source 104 may be provided as a QCW or CW laser source and may not include a pulse gating unit. As such, laser source 104 can be broadly characterized as being capable of generating a beam of laser energy that can be represented as a series of laser pulses or as a continuous or quasi-continuous laser beam that can then propagate along beam path 114. While many of the embodiments described herein refer to laser pulses, it should be understood that a continuous or quasi-continuous beam can alternatively or additionally be used where appropriate or necessary.

[0035] The laser energy output by laser source 104 can have one or more wavelengths in the ultraviolet (UV), visible, or infrared (IR) regions of the electromagnetic spectrum. Laser energy in the UV region of the electromagnetic spectrum may have one or more wavelengths in the range of 10 nm (or thereabouts) to 385 nm (or thereabouts), such as 100 nm, 121 nm, 124 nm, 157 nm, 200 nm, 334 nm, 337 nm, 351 nm, 380 nm, etc., or wavelengths between any of these values. Laser energy in the visible green region of the electromagnetic spectrum may have one or more wavelengths in the range of 500 nm (or thereabouts) to 560 nm (or thereabouts), such as 511 nm, 515 nm, 530 nm, 532 nm, 543 nm, 568 nm, etc., or wavelengths between any of these values. Laser energy in the IR region of the electromagnetic spectrum may have one or more wavelengths in the range of 750 nm (or thereabouts) to 15 μm (or thereabouts), such as 600 nm to 1000 nm, 752.5 nm, 780 nm to 1060 nm, 799.3 nm, 980 nm, 1047 nm, 1053 nm, 1060 nm, 1064 nm, 1080 nm, 1090 nm, 1152 nm, 1150 nm to 1350 nm, 1540 nm, 2.6 μm to 4 μm, 4.8 μm to 8.3 μm, 9.4 μm, 10.6 μm, etc., or wavelengths between any of these values.

[0036] When the laser energy beam is represented as a train of laser pulses, the laser pulses output by the laser source 104 may have a pulse width or pulse duration (i.e., based on the full width at half maximum (FWHM) of the optical power in the pulse with respect to time) ranging from 10 fs to 900 ms, although it will be understood that the pulse duration may be shorter than 10 fs or longer than 900 ms. Thus, the at least one laser pulse output by the laser source 104 may be 10 fs, 15 fs, 30 fs, 50 fs, 100 fs, 150 fs, 200 fs, 300 fs, 500 fs, 600 fs, 750 fs, 800 fs, 850 fs, 900 fs, 950 fs, 1 ps, 2 ps, 3 ps, 4 ps, 5 ps, 7 ps, 10 ps, ​​15 ps, 25 ps, 50 ps, ​​75 ps, 100 ps, ​​200 ps, ​​500 ps, ​​1 ns, 1.5 ns, 2 ns, 5 ns, 10 ns, 20 ns, 50 ns, 10 The pulse duration may be shorter, longer, or equal to 0 ns, 200 ns, 400 ns, 800 ns, 1000 ns, 2 μs, 5 μs, 10 μs, 15 μs, 20 μs, 25 μs, 30 μs, 40 μs, 50 μs, 100 μs, 300 μs, 500 μs, 900 μs, 1 ms, 2 ms, 5 ms, 10 ms, 20 ms, 50 ms, 100 ms, 300 ms, 500 ms, 900 ms, 1 s, etc., or any value between these values.

[0037] The laser pulses output by the laser source 104 can have an average power ranging from 5 mW to 50 kW. However, it will be understood that the average power can be less than 5 mW or greater than 50 kW. Thus, the laser pulses output by the laser source 104 can have an average power less than, greater than, or equal to 5 mW, 10 mW, 15 mW, 20 mW, 25 mW, 50 mW, 75 mW, 100 mW, 300 mW, 500 mW, 800 mW, 1 W, 2 W, 3 W, 4 W, 5 W, 6 W, 7 W, 10 W, 15 W, 18 W, 25 W, 30 W, 50 W, 60 W, 100 W, 150 W, 200 W, 250 W, 500 W, 2 kW, 3 kW, 20 kW, 50 kW, etc., or any value between these values.

[0038] Laser pulses may be output by laser source 104 at a pulse repetition rate ranging from 5 kHz to 5 GHz. However, it will be understood that the pulse repetition rate may be less than 5 kHz or greater than 5 GHz. Thus, laser pulses may be output by laser source 104 at pulse repetition rates less than, greater than, or equal to 5 kHz, 50 kHz, 100 kHz, 175 kHz, 225 kHz, 250 kHz, 275 kHz, 500 kHz, 800 kHz, 900 kHz, 1 MHz, 1.5 MHz, 1.8 MHz, 1.9 MHz, 2 MHz, 2.5 MHz, 3 MHz, 4 MHz, 5 MHz, 10 MHz, 20 MHz, 50 MHz, 60 MHz, 100 MHz, 150 MHz, 200 MHz, 250 MHz, 300 MHz, 350 MHz, 500 MHz, 550 MHz, 600 MHz, 900 MHz, 2 GHz, 10 GHz, etc., or any value between these values.

[0039] In addition to wavelength, average power, and, if the laser energy beam is represented as a series of laser pulses, pulse duration and pulse repetition rate, the laser energy beam irradiating the workpiece 102 may be characterized by one or more other properties, such as pulse energy, peak power, etc. Such properties determine the optical intensity (W / cm) sufficient to process the workpiece 102 (e.g., to form one or more features). 2 (measured in J / cm) and fluence (J / cm 2 The wavelength, pulse duration, average power, pulse repetition rate, and other characteristics, as needed, can be selected (e.g., based on one or more other characteristics, such as wavelength, pulse duration, average power, pulse repetition rate, etc.) to irradiate a process spot on the workpiece 102, such as measured by the wavelength, pulse duration, average power, pulse repetition rate, and so on.

[0040] Examples of types of lasers that may characterize the laser source 104 include gas lasers (e.g., carbon dioxide lasers, carbon monoxide lasers, excimer lasers, etc.), solid-state lasers (e.g., Nd:YAG lasers, etc.), rod lasers, fiber lasers, photonic crystal rod / fiber lasers, passively modelocked solid-state bulk or fiber lasers, dye lasers, modelocked diode lasers, pulsed lasers (e.g., ms pulsed lasers, ns pulsed lasers, ps pulsed lasers, fs pulsed lasers), CW lasers, quasi-CW lasers, etc., or any combination thereof. In some configurations, gas lasers (e.g., carbon dioxide lasers, etc.) may be configured to operate in one or more modes (e.g., CW mode, quasi-CW mode, pulsed mode, or any combination thereof). Specific examples of laser sources that can be provided as laser source 104 include BOREAS, HEGOA, SIROCCO, or CHINOOK series lasers manufactured by EOLITE, PYROFLEX series lasers manufactured by PYROPHOTONICS, PALADIN Advanced 355 or DIAMOND series (e.g., DIAMOND E series, G series, J-2 series, J-3 series, J-5 series) manufactured by COHERENT, FLARE NX series, MATRIX QS DPSS series, MEPHISTO Q series, AVIA LX series, AVIA NX series, RAPID NX series, HYPERRAPID NX series, RAPID series, HELIOS series, FIDELITY series, MONACO series, OPERA series, or RAPID FX series lasers, SPECTRA ASCEND series, EXCELSIOR series, EXPLORER series, HIPPO series, NAVIGATOR series, QUANTA-RAY series, QUASAR series, SPIRIT series, TALON series, or VGEN series lasers manufactured by PHYSICS, PULSTAR series or FIRESTAR series lasers manufactured by SYNRAD, and TRUFLOW series lasers (e.g., TRUFLOW2000, 2600, 3000, 3200, 3600, 4000, 5000, 6000, 6000, 8000, 10000, 12000, 15000, 20000), TRUCOAX series lasers (e.g., TRUCOAX 1000) or TRUDISK series, TRUPULSE series, TRUDIODE series, TRUFIBER series, or TRUMICRO series lasers, FCPA μJEWEL or FEMTOLITE series lasers manufactured by IMRA AMERICA, TANGERINE and SATSUMA series lasers (and MIKAN and T-PULSE series oscillators) manufactured by AMPLITUDE SYSTEMES, IPG and one or more laser sources such as the CL series, CLPF series, CLPN series, CLPNT series, CLT series, ELM series, ELPF series, ELPN series, ELPP series, ELR series, ELS series, FLPN series, FLPNT series, FLT series, GLPF series, GLPN series, GLR series, HLPN series, HLPP series, RFL series, TLM series, TLPN series, TLR series, ULPN series, ULR series, VLM series, VLPN series, YLM series, YLPF series, YLPN series, YLPP series, YLR series, YLS series, FLPM series, FLPMT series, DLM series, BLM series, or DLR series lasers manufactured by PHOTONICS (including, for example, GPLN-100-M, GPLN-500-QCW, GPLN-500-M, GPLN-500-R, GPLN-2000-S, etc.), or the like, or any combination thereof.

[0041] B. First positioner Generally, the first positioner 106 is adapted to move the beam axis 118 relative to the workpiece 102 along the X-axis (or X-direction), the Y-axis (or Y-direction), or a combination thereof (e.g., by deflecting the beam path 114 within a first primary angular range 116a, a second primary angular range 116b, or a combination thereof). Although not shown, the Y-axis (or Y-direction) will be understood to mean an axis (or direction) that is orthogonal to the illustrated X-axis (or X-direction) and Z-axis (or Z-direction).

[0042] In one embodiment, the operation of the first positioner 106 may be controlled to deflect the beam path 114 to the second positioner 108a (e.g., during a first branching period) and to deflect the beam path 114 to the second positioner 108b (e.g., during a second branching period after the first branching period), or vice versa, or a combination thereof. In another example, the operation of the first positioner 106 may be controlled to simultaneously deflect the beam path 114 to the second positioner 108a and the second positioner 108b. In the embodiments described herein, the length of the first branching period may be longer, shorter, or equal to the length of the second branching period. The lengths of the first branching period and the second branching period may each be longer, shorter, or equal to the positioning period of the first positioner 106. In one embodiment, the length of each of the first and second branch periods can be characterized as an integer multiple of the positioning period of the first positioner 106 (this integer can be 1, 2, 3, 4, 5, 10, 20, 50, 100, etc., or any integer between any of these values). See the section below for further discussion regarding the "positioning period" of the first positioner 106. In some embodiments, the length of each branch period may be longer than, shorter than, or equal to 200 μs, 125 μs, 100 μs, 50 μs, 33 μs, 25 μs, 20 μs, 13.3 μs, 12.5 μs, 10 μs, 4 μs, 2 μs, 1.3 μs, 1 μs, 0.2 μs, 0.1 μs, 0.05 μs, 0.025 μs, 0.02 μs, 0.013 μs, 0.01 μs, 0.008 μs, 0.0067 μs, 0.0057 μs, 0.0044 μs, 0.004 μs, etc., or any value between these values.

[0043] When the laser energy beam output by the laser source 104 is represented as a series of laser pulses, each branching period may have a duration equal to or greater than the pulse duration of a laser pulse in the laser energy beam. However, in other embodiments, one or more branching periods may have a duration shorter than the pulse duration of a laser pulse in the laser energy beam. In such embodiments, beam branching may result in the laser pulse being separated in time. Therefore, this beam branching may also be referred to as “pulse slicing.” Pulse slicing, which will be described in more detail below, may be performed in conjunction with beam branching or separately from beam branching. That is, pulse slicing may be achieved when the first positioner 106 is operated to deflect the beam path 114 at different angles within a single primary angular range 116 (e.g., within the first primary angular range 116a or the second primary angular range 116b). In this manner, pulse slicing may be performed in conjunction with beam branching or separately from beam branching. The periods over which laser pulses are separated in time can be collectively referred to as “slice periods.” Although pulse slicing techniques are described herein as being applied to separate laser pulses in time, it will be understood that these techniques can equally be applied to separate in time beams of laser energy represented as continuous or quasi-continuous laser beams.

[0044] Beam axis movement by the first positioner 106 relative to the workpiece 102 is generally limited to scan, move, or position the process spot within a first scan area projected by the scan lens 112. Generally, depending on one or more factors such as the configuration of the first positioner 106, the location of the first positioner 106 along the beam path 114, and the beam size of the laser energy beam incident on the first positioner 106, the first scan area may extend to a distance less than, greater than, or equal to 0.01 mm, 0.04 mm, 0.1 mm, 0.5 mm, 1.0 mm, 1.4 mm, 1.5 mm, 1.8 mm, 2 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.2 mm, 5 mm, 10 mm, 25 mm, 50 mm, 60 mm, etc., or any value between these values, in either the X or Y direction. As used herein, the term "beam size" refers to the diameter or width of the laser energy beam, and refers to the distance from the beam axis where the optical intensity is 1 / e of the optical intensity at the axis of propagation along the beam path 114. 2 The maximum dimension of the first scan area (e.g., in the X or Y direction, or other direction) may be greater than, equal to, or less than a corresponding maximum dimension (measured in the XY plane) of a feature (e.g., opening, recess, via, trench, etc.) to be formed in the workpiece 102.

[0045] Generally, the first positioner 106 may be provided as a galvanometer mirror system, an AO deflector (AOD) system, an electro-optical (EO) deflector (EOD) system, a fast steering mirror (FSM) system, or the like, or any combination thereof. The AOD of an AOD system typically includes an AO cell formed from a material such as crystalline germanium (Ge), gallium arsenide (GaAs), pyrite (PbMoO), tellurium dioxide (TeO), quartz, vitreous SiO, arsenic trisulfide (AsS), lithium niobate (LiNbO), or the like, or any combination thereof. The EOD of an EOD system typically includes an EO cell formed from lithium niobate, potassium tantalite niobate, or the like. To the extent that the AO and EO cells are configured to transmit the incident laser energy beam, the AO and EO cells can be considered types of transmissive optical components.

[0046] The first positioner 106 can be characterized as having a "first positioning speed," which refers to the speed at which the first positioner 106 positions the process spot (and thereby moves the beam axis) anywhere within the first scan region. For example, the first positioning speed can be greater than or less than 8 kHz, 10 kHz, 20 kHz, 30 kHz, 40 kHz, 50 kHz, 75 kHz, 80 kHz, 100 kHz, 250 kHz, 500 kHz, 750 kHz, 1 MHz, 5 MHz, 10 MHz, 20 MHz, 40 MHz, 50 MHz, 75 MHz, 100 MHz, 125 MHz, 150 MHz, 175 MHz, 200 MHz, 225 MHz, 250 MHz, etc., or a value between any of these values. This range is also referred to herein as the first positioning bandwidth. During operation of the first positioner 106, a drive signal is repeatedly applied to the first positioner 106, and the first positioning bandwidth corresponds to (is equal to, or at least substantially equal to) the rate at which the drive signal is applied. The rate at which the drive signal is applied is also referred to as the “update rate” or “refresh rate.” As used herein, the inverse of the first positioning rate is referred to as the “first positioning period,” which refers to the shortest time it takes for the position of the process spot to change from one location within the first scan area to another location within the first scan area. Thus, the first positioner 106 can be characterized as having a first positioning period that is greater than or less than 200 μs, 125 μs, 100 μs, 50 μs, 33 μs, 25 μs, 20 μs, 15 μs, 13.3 μs, 12.5 μs, 10 μs, 4 μs, 2 μs, 1.3 μs, 1 μs, 0.2 μs, 0.1 μs, 0.05 μs, 0.025 μs, 0.02 μs, 0.013 μs, 0.01 μs, 0.008 μs, 0.0067 μs, 0.0057 μs, 0.0044 μs, 0.004 μs, etc., or a value between any of these values.

[0047] i. Embodiments Generally Relating to an AOD System as a First Positioner In one embodiment, the first positioner 106 is provided as an AOD system including at least one (e.g., one, two, three, four, five, six, etc.) single-element AOD, at least one (e.g., one, two, three, four, five, six, etc.) multi-element AOD, etc., or any combination thereof. As used herein, an AOD system including only one AOD is referred to as a "single-cell AOD system," and an AOD system including more than one AOD is referred to as a "multi-cell AOD system." As used herein, a "single-element" AOD refers to an AOD with only one ultrasonic transducer element acoustically coupled to an AO cell, and a "multi-element" AOD includes two or more ultrasonic transducer elements acoustically coupled to a common AO cell. The AOD system may be provided as a single-axis AOD system (e.g., capable of deflecting the beam axis along a single axis) or as a multi-axis AOD system (e.g., capable of deflecting the beam axis along one or more axes, e.g., along the X-axis, the Y-axis, or any combination thereof) by deflecting the beam path 114 in a corresponding manner. Generally, a multi-axis AOD system may be provided as a single-cell AOD system or a multi-cell AOD system. A multi-cell multi-axis AOD system typically includes multiple AODs, each capable of deflecting its beam axis along a different axis. For example, a multi-cell multi-axis system may include a first AOD (e.g., a single-element or multi-element AOD system) capable of deflecting its beam axis along one axis (e.g., along the X-axis) and a second AOD (e.g., a single-element or multi-element AOD) capable of deflecting its beam axis along a second axis (e.g., along the Y-axis). A single-cell multi-axis system typically includes a single AOD capable of deflecting its beam axis along two axes (e.g., along the X-axis and the Y-axis). For example, a single-cell multi-axis system may include two or more ultrasound transducer elements acoustically coupled to orthogonally arranged planar faces, facets, sides, etc. of a common AO cell.

[0048] As will be appreciated by those skilled in the art, AO technology (e.g., AODs, AOMs, etc.) utilizes the diffraction effect produced by one or more acoustic waves propagating through the AO cell (along the “diffraction axis” of the AOD) to diffract an incident light wave (i.e., in the context of this application, a laser energy beam) simultaneously propagating through the AO cell (along the “optical axis” within the AOD). Diffraction of the incident laser energy beam produces a diffraction pattern that typically includes zero- and first-order diffraction peaks, but may also include other diffraction peaks of higher orders (e.g., second, third, etc.). As known in the art, the portion of the laser energy beam diffracted at the zero-order diffraction peak is referred to as the “zero-order” beam, the portion of the laser energy beam diffracted at the first-order diffraction peak is referred to as the “first-order” beam, and so on. Generally, the zero-order beam and other order beams (e.g., first-order beams) propagate along different beam paths as they exit the AO cell (e.g., through the light output side of the AO cell). For example, the zero order beam propagates along the zero order beam path, the first order beam propagates along the first order beam path, and so on.

[0049] Acoustic waves are typically input to the AO cell by applying an RF drive signal (e.g., from one or more drivers of the first positioner 106) to an ultrasonic transducer element. Thus, an AOD system can be operated by applying an RF drive signal to one or more ultrasonic transducer elements of the AOD system. Characteristics (e.g., amplitude, frequency, phase, etc.) of the RF drive signal can be controlled (e.g., based on one or more control signals output by the controller 122, a component-specific controller, etc., or any combination thereof) to adjust how incident optical waves are diffracted. For example, the frequency of a given RF drive signal determines the angle by which the beam path 114 is deflected. As is known in the art, the angle Θ by which the beam path 114 is deflected can be calculated as follows:

number

[0050] The primary beam path exiting the AO cell can typically be considered to be the beam path 114 rotated or deflected within the AO cell. Unless otherwise indicated herein, the beam path 114 exiting the AO cell corresponds to the primary beam path. The axis (also referred to herein as the “rotation axis”) about which the beam path 114 exiting the AO cell is rotated (e.g., relative to the beam path 114 as it entered the AO cell) is orthogonal to both the diffraction axis of the AO cell and the optical axis along which the incident laser energy beam propagates within the AO cell when the AOD is operated or driven to diffract the incident laser energy beam. In this manner, the AOD deflects the incident beam path 114 within a plane (also referred to herein as the “deflection plane”) that contains (or is otherwise substantially parallel to) the diffraction axis of the AO cell and the optical axis within the AO cell. The spatial range over which the AOD can deflect the beam path 114 within the deflection plane is referred to herein as the “scan region” of the AOD. Therefore, the first scan area of ​​the first positioner 106 can be considered to correspond to the scan area of ​​a single AOD (e.g., if the first positioner 106 includes a single AOD), or to correspond to the combined scan area of ​​multiple AODs (e.g., if the first positioner 106 includes multiple AODs).

[0051] It will be appreciated that the material forming the AO cell will depend on the wavelength of the laser energy propagating along beam path 114 to be incident on the AO cell. For example, if the wavelength of the deflected laser energy is in the range of 2 μm (or thereabouts) to 20 μm (or thereabouts), materials such as crystalline germanium can be used; if the wavelength of the deflected laser energy is in the range of 1 μm (or thereabouts) to 11 μm (or thereabouts), materials such as gallium arsenide and arsenic trisulfide can be used; and if the wavelength of the deflected laser energy is in the range of 200 nm (or thereabouts) to 5 μm (or thereabouts), materials such as vitreous SiO2, quartz, lithium niobate, pyrite, and tellurium dioxide can be used.

[0052] C. Second positioner In general, the second positioner 108 can move the beam axis relative to the workpiece 102 along the X-axis (or X-direction), the Y-axis (or Y-direction), or a combination thereof (e.g., by deflecting the beam path 114 within a first secondary angular range 118a or a second secondary angular range 118b).

[0053] The beam axis movement relative to the workpiece 102 provided by the second positioner 108 is generally limited to scanning, moving, or positioning the process spot within a second scan area projected by the scan lens 112. Generally, the second scan area may extend a distance in either the X or Y direction that is greater than the corresponding distance of the first scan area, depending on one or more factors such as the configuration of the second positioner 108, the location of the second positioner 108 along the beam path 114, the beam size of the laser energy beam incident on the second positioner 108, and the spot size. In view of the above, the second scan area may extend in either the X or Y direction to a distance less than, greater than, or equal to 1 mm, 25 mm, 50 mm, 75 mm, 100 mm, 250 mm, 500 mm, 750 mm, 1 cm, 25 cm, 50 cm, 75 cm, 1 m, 1.25 m, 1.5 m, etc., or any value between these values. The maximum dimension of the second scan area (e.g., in the X or Y direction or other direction) may be greater than, equal to, or less than the maximum dimension (measured in the XY plane) of a feature (e.g., opening, recess, via, trench, scribe line, conductive trace, etc.) formed in the workpiece 102.

[0054] In view of the configurations described herein, the beam axis movement performed by the first positioner 106 can be superimposed on the beam axis movement performed by the second positioner 108. Thus, the second positioner 108 can scan the first scan area within the second scan area.

[0055] Generally, the positioning speed at which the second positioner 108 can position the process spot anywhere within the second scan area (thereby moving the beam axis within the second scan area and / or scanning the first scan area within the second scan area) ranges less than the first positioning bandwidth (also referred to herein as the "second positioning bandwidth"). In one embodiment, the second positioning bandwidth ranges from 500 Hz (or thereabouts) to 8 kHz (or thereabouts). For example, the second positioning bandwidth may be greater than, equal to, or less than 500 Hz, 750 Hz, 1 kHz, 1.25 kHz, 1.5 kHz, 1.75 kHz, 2 kHz, 2.5 kHz, 3 kHz, 3.5 kHz, 4 kHz, 4.5 kHz, 5 kHz, 5.5 kHz, 6 kHz, 6.5 kHz, 7 kHz, 7.5 kHz, 8 kHz, etc., or any value between these values.

[0056] In one embodiment, the second positioner 108 may be provided as a galvanometer mirror system including two galvanometer mirror components: a first galvanometer mirror component (e.g., an X-axis galvanometer mirror component) configured to move the beam axis along the X-axis relative to the workpiece 102, and a second galvanometer mirror component (e.g., a Y-axis galvanometer mirror component) configured to move the beam axis along the Y-axis relative to the workpiece 102. However, in other embodiments, the second positioner 108 may be provided as a galvanometer mirror system including only a single galvanometer mirror component configured to move the beam axis along the X-axis and the Y-axis relative to the workpiece 102. In still other embodiments, the second positioner 108 may be provided as a rotating polygon mirror system, or the like. Thus, it will be appreciated that depending on the particular configuration of the second positioner 108 and the first positioner 106, the second positioning bandwidth may be greater than or equal to the first positioning bandwidth.

[0057] D. Third Positioner The third positioner 110 moves the workpiece 102 (e.g., workpieces 102a and 102b) relative to the scan lens 112, thereby moving the workpiece 102 relative to the beam axis. The movement of the workpiece 102 relative to the beam axis is generally limited to allow scanning, moving, or positioning of the process spot within the third scan area. Depending on one or more factors, such as the configuration of the third positioner 110, the third scan area may extend in the X direction, the Y direction, or any combination thereof, a distance greater than or equal to the corresponding distance of the second scan area. However, typically, the maximum dimension of the third scan area (e.g., in the X direction or Y direction, or other direction) is greater than or equal to the corresponding maximum dimension (measured in the XY plane) of a feature formed on the workpiece 102. If desired, the third positioner 110 may be capable of moving the workpiece 102 relative to the beam axis within a scan region extending in the Z direction (e.g., over a range of 1 mm to 50 mm). Thus, the third scan region may extend along the X, Y, and / or Z directions.

[0058] It should be understood that, in view of the configurations described herein, movement of the process spot relative to the workpiece 102 (e.g., by the first positioner 106 and / or the second positioner 108) can be superimposed on movement of the workpiece 102 by the third positioner 110. Thus, the third positioner 110 can scan the first scan area and / or the second scan area within the third scan area. Generally, the positioning speed at which the third positioner 110 can position the workpiece 102 anywhere within the third scan area (thereby moving the workpiece 102 to scan the first scan area within the third scan area and / or scan the second scan area within the third scan area) ranges less than the second positioning bandwidth (also referred to herein as the "third positioning bandwidth"). In one embodiment, the third positioning bandwidth is less than (or about) 500 Hz. For example, the third positioning bandwidth may be equal to or lower than 500 Hz, 250 Hz, 150 Hz, 100 Hz, 75 Hz, 50 Hz, 25 Hz, 10 Hz, 7.5 Hz, 5 Hz, 2.5 Hz, 2 Hz, 1.5 Hz, 1 Hz, etc., or a value between any of these values.

[0059] In one embodiment, the third positioner 110 is provided as one or more linear stages (e.g., capable of imparting translational movement to the workpiece 102 along the X, Y, and / or Z directions, respectively), one or more rotary stages (e.g., capable of imparting rotational movement to the workpiece 102 about axes parallel to the X, Y, and / or Z directions, respectively), or any combination thereof. In one embodiment, the third positioner 110 includes an X stage for moving the workpiece 102 along the X direction, and a Y stage supported by the X stage (and thereby movable along the X direction by the X stage) for moving the workpiece 102 along the Y direction.

[0060] Although not shown, the apparatus 100 may optionally include a fixture (e.g., a chuck) coupled to a stage of the third positioner 110. The fixture may include a support area within which the workpiece 102 may be mechanically clamped, secured, held, affixed, or supported by the fixture. In one embodiment, the workpiece 102 may be clamped, secured, held, affixed, or supported in direct contact with a typically flat main support surface of the fixture. In other embodiments, the workpiece 102 may be clamped, secured, held, affixed, or supported away from the support surface of the fixture. In one embodiment, the workpiece 102 may be clamped, secured, held, affixed, or supported by a force (e.g., electrostatic, vacuum, magnetic) selectively applied to the workpiece 102 from the fixture or present between the workpiece 102 and the fixture.

[0061] As previously mentioned, apparatus 100 may use a so-called “stacked” positioning system for third positioner 110. This “stacked” positioning system allows workpiece 102 to be moved while other components, such as first positioner 106, second positioner 108, and scan lens 112, remain stationary within apparatus 100 relative to workpiece 102 (e.g., via one or more supports, frames, etc., as known in the art). In other embodiments, third positioner 110 may be positioned and operated to move one or more components, such as first positioner 106, second positioner 108, scan lens 112, etc., or any combination thereof, while workpiece 102 may remain stationary.

[0062] In yet other embodiments, the third positioner 110 may be provided as a so-called "split-axis" positioning system, in which one or more components, such as the first positioner 106, the second positioner 108, the scan lens 112, etc., or any combination thereof, are carried by one or more linear or rotary stages (e.g., mounted on a frame, gantry, etc.), and the workpiece 102 is carried by one or more other linear or rotary stages. In such embodiments, the third positioner 110 includes one or more linear or rotary stages positioned and operable to move one or more components, such as the scan head (e.g., including the second positioner 108 and the scan lens 112), and one or more linear or rotary stages positioned and operable to move the workpiece 102. For example, the third positioner 110 may include a Y-stage that moves the workpiece 102 along the Y-direction and an X-stage that moves the scan head along the X-direction. Examples of split-axis positioning systems that may be beneficially or advantageously utilized in apparatus 100 include any or any combination of those disclosed in U.S. Patent Nos. 5,751,585, 5,798,927, 5,847,960, 6,606,999, 7,605,343, 8,680,430, 8,847,113, or U.S. Patent Application Publication No. 2014 / 0083983, each of which is incorporated herein by reference in its entirety.

[0063] In one embodiment in which the third positioner 110 includes a Z stage, the Z stage may be positioned and configured to move the workpiece 102 along the Z direction. In this case, the Z stage may be carried by one or more of the other stages described above for moving or positioning the workpiece 102, or may carry one or more of the other stages described above for moving or positioning the workpiece 102, or any combination thereof. In other embodiments in which the third positioner 110 includes a Z stage, the Z stage may be positioned and configured to move the scan head along the Z direction. Thus, when the third positioner 110 is provided as a split-axis positioning system, the Z stage may carry or be carried by the X stage. Moving the workpiece 102 or the scan head along the Z direction can change the spot size on the workpiece 102.

[0064] In yet other embodiments, one or more components, such as first positioner 106, second positioner 108, and scan lens 112, may be carried by a multi-axis articulated robot arm (e.g., a two-axis, three-axis, four-axis, five-axis, or six-axis arm). In such embodiments, second positioner 108 and / or scan lens 112 may be carried by an end effector of the robot arm, as needed. In yet other embodiments, workpiece 102 may be carried directly on the end effector of the multi-axis articulated robot arm (i.e., without third positioner 110). In yet other embodiments, third positioner 110 may be carried on the end effector of the multi-axis articulated robot arm.

[0065] D. Scan lens Generally, the scan lens 112 (e.g., provided as either a simple lens or a compound lens) is typically configured to focus a laser energy beam directed along a beam path to produce a beam waist that may be located at or near a desired process spot. The scan lens 112 may be provided as an f-theta lens, a telecentric lens, an axicon lens (in which case a series of beam waists are produced, resulting in multiple process spots offset from one another along the beam axis), or the like, or any combination thereof. The scan lens 112 may be provided as a non-telecentric lens (as shown), an f-theta lens, a telecentric lens, an axicon lens (in which case a series of beam waists are produced, resulting in multiple process spots offset from one another along the beam axis), or the like, or any combination thereof.

[0066] In one embodiment, the scan lens 112 is provided as a fixed focal length lens and is coupled to a scan lens positioner (e.g., a lens actuator, not shown) that can move the scan lens 112 (e.g., to change the position of the beam waist along the beam axis). For example, the lens actuator can be provided as a voice coil that can linearly translate the scan lens 112 along the Z direction. In this case, the scan lens 112 can be formed from materials such as fused silica, optical glass, zinc selenide, zinc sulfide, germanium, gallium arsenide, magnesium fluoride, etc. In other embodiments, the scan lens 112 is provided as a variable focal length lens (e.g., a zoom lens or a so-called "liquid lens" incorporating technology currently offered by COGNEX, VARIOPTIC, etc.) that can be actuated (e.g., via a lens actuator) to change the position of the beam waist along the beam axis. Varying the position of the beam waist along the beam axis can change the spot size at the workpiece 102.

[0067] In embodiments in which apparatus 100 includes a lens actuator, the lens actuator may be coupled to scan lens 112 (e.g., to allow scan lens 112 to move relative to second positioner 108 within the scan head). Alternatively, the lens actuator may be coupled to scan head 120 (e.g., to allow the scan head itself to move, where scan lens 112 and second positioner 108 move together). In other embodiments, scan lens 112 and second positioner 108 are integrated into different housings (e.g., such that the housing in which scan lens 112 is integrated is movable relative to the housing in which second positioner 108 is integrated).

[0068] F. Controller Generally, apparatus 100 includes one or more controllers, such as controller 122, for controlling or facilitating the control and operation of apparatus 100. In one embodiment, controller 122 is communicatively coupled (e.g., via one or more wired or wireless serial or parallel communication links, such as USB, RS-232, Ethernet, Firewire, Wi-Fi, RFID, NFC, Bluetooth, Li-Fi, SERCOS, MARCO, EtherCAT, etc., or any combination thereof) to one or more components of apparatus 100, such as laser source 104, first positioner 106, second positioner 108, third positioner 110, lens actuator, scan lens 112 (if provided as a variable focal length lens), fixture, etc., such that these components operate in response to one or more control signals output by controller 122.

[0069] For example, the controller 122 may control the operation of the first positioner 106, the second positioner 108, or the third positioner 110, or any combination thereof, to effect relative movement between the beam axis and the workpiece, and to effect relative motion between the process spot and the workpiece 102 along a path or trajectory (also referred to herein as a "process trajectory") within the workpiece 102. It will be appreciated that any two of these positioners, or all three of these, may be controlled such that two positioners (e.g., the first positioner 106 and the second positioner 108, the first positioner 106 and the third positioner 110, the second positioner 108 and the third positioner 110) or all three positioners simultaneously effect relative movement between the process spot and the workpiece 102 (thereby effecting a "compound relative movement" between the beam axis and the workpiece). Of course, at any one time, it is also possible to control only one positioner (e.g., first positioner 106, second positioner 108, or third positioner 110) to cause relative movement between the process spot and workpiece 102 (thereby causing "non-compound relative movement" between the beam axis and the workpiece).

[0070] In one embodiment, the controller 122 may control the operation of the first positioner 106 to deflect the beam path 114 within each primary angular range 116 in a manner that results in compound or non-compound relative movement between the beam axis and each workpiece 102 (e.g., in conjunction with a corresponding second positioner 108, or in conjunction with a third positioner 110, or in conjunction with any combination thereof) to result in relative movement between the process spot and the workpiece 102 along a process trajectory within the workpiece 102. For example, the operation of the first positioner 106 can be controlled to deflect the beam path 114 within a first primary angular range 116a in a manner that causes compound or non-compound relative movement between the beam axis and the workpiece 102a (e.g., in coordination with a corresponding second positioner 108a, or in coordination with a third positioner 110, or in coordination with any combination thereof) to cause relative movement between the process spot and the workpiece 102a along a first process trajectory within the workpiece 102a. Similarly, operation of the first positioner 106 can be controlled to deflect the beam path 114 within a second primary angular range 116b in a manner that produces compound or non-compound relative motion between the beam axis and the workpiece 102b (e.g., in conjunction with a corresponding second positioner 108b, or in conjunction with a third positioner 110, or any combination thereof) to produce relative motion between the process spot and the workpiece 102b along a second process trajectory within the workpiece 102b. The first process trajectory may be the same as or different from the second process trajectory.

[0071] In other embodiments, the controller 122 may control the operation of the first positioners 106 to deflect the beam path 114 within each primary angular range 116 in a manner that compensates for tracking errors introduced by the corresponding second positioners 108. For example, the controller 122 may control the operation of the first positioners 106 to deflect the beam path 114 within the first primary angular range 116a in a manner that compensates for tracking errors introduced by the corresponding second positioner 108a. Similarly, the controller 122 may control the operation of the first positioners 106 to deflect the beam path 114 within the second primary angular range 116b in a manner that compensates for tracking errors introduced by the corresponding second positioner 108b.

[0072] Other examples of actions that can be controlled to be performed by one or more of the above-described components include those disclosed in the above-mentioned U.S. Patent Nos. 5,751,585, 5,847,960, 6,606,999, 8,680,430, and 8,847,113, or those disclosed in U.S. Patent Nos. 4,912,487, 5,633,747, 5,638,267, 5,917,300, 6,300, and 6,300. No. 14,463, No. 6,430,465, No. 6,600,600, No. 6,606,998, No. 6,816,294, No. 6,947,454, No. 7,019,891, No. 7,027,199 , No. 7,133,182, No. 7,133,186, No. 7,133,187, No. 7,133,188, No. 7,244,906, No. 7,245,412, No. 7,259,354, No. 7,611, 745, 7,834,293, 8,026,158, 8,076,605, 8,288,679, 8,404,998, 8,497,450, 8,648,277, 8,896,909, 8,928,853, 9,259,802, or as disclosed in U.S. Patent Application Publication Nos. 2014 / 0026351, 2014 / 0196140, 2 014 / 0263201, 2014 / 0263212, 2014 / 0263223, 2014 / 0312013, or in German Federal Patent No. DE102013201968B4, or in International Patent Publication No. WO2009 / 087392, or any combination thereof, each of which is incorporated herein by reference in its entirety.In another example, the controller 122 may control the operation of any positioner, including one or more AODs (e.g., in one embodiment, the first positioner 106, the second positioner 108, or a combination thereof), to vary the spot shape or spot size of the laser energy beam irradiated at the process spot (e.g., by chirping the RF signal applied to one or more ultrasonic transducer elements of one or more AODs, by applying a spectrally shaped RF signal to one or more ultrasonic transducer elements of one or more AODs, or the like, or any combination thereof), as disclosed, for example, in International Patent Publication No. WO 2017 / 044646 A1, which is incorporated herein by reference in its entirety. The applied RF signal may be chirped linearly or nonlinearly in any desired or suitable manner. For example, the applied RF signal may be chirped at a first rate and then at a second rate to diffract the laser energy beam passing through the AO cell in two different ways. In this case, the first speed may be slower or faster than the second speed.

[0073] Typically, the controller 122 includes one or more processors operable to execute instructions to generate the control signals described above. The processor may be provided as a programmable processor (e.g., one or more general-purpose computer processors, microprocessors, digital signal processors, etc., or any combination thereof) operable to execute instructions. The instructions executable by the processor may be implemented as software, firmware, etc., or any suitable form of circuitry (including digital, analog, or mixed analog / digital circuitry) including programmable logic devices (PLDs), field programmable gate arrays (FPGAs), field programmable object arrays (FPOAs), application-specific integrated circuits (ASICs), etc., or any combination thereof. Execution of the instructions may occur on a single processor, distributed across multiple processors, in parallel across multiple processors within a device or across a network of devices, or the like, or any combination thereof.

[0074] In one embodiment, the controller 122 includes tangible media, such as computer memory, accessible by the processor (e.g., via one or more wired or wireless communication links). As used herein, "computer memory" includes magnetic media (e.g., magnetic tape, hard disk drives, etc.), optical disks, volatile or non-volatile semiconductor memory (e.g., RAM, ROM, NAND flash memory, NOR flash memory, SONOS memory, etc.), etc., and may be locally accessible, remotely accessible (e.g., over a network), or any combination thereof. Generally, instructions may be stored as computer software (e.g., executable code, files, instructions, etc., library files, etc.). Such computer software may be written in, for example, C, C++, Visual Basic, Java, Python, Tel, Perl, Scheme, Ruby, assembly language, hardware description languages ​​(e.g., VHDL, VERILOG, etc.), etc., and may be readily produced by one of ordinary skill in the art from the description provided herein. Computer software is typically stored in one or more data structures carried by the computer memory.

[0075] Although not shown, one or more drivers (e.g., RF drivers, servo drivers, line drivers, power supplies, etc.) may be communicatively coupled to inputs of one or more components, such as the laser source 104, the first positioner 106, the second positioner 108, the third positioner 110, the lens actuator, the scan lens 112 (if provided as a variable focal length lens), the fixture, etc., to control such components. Accordingly, one or more components, such as the laser source 104, the first positioner 106, the second positioner 108, the third positioner 110, the lens actuator, the scan lens 112 (if provided as a variable focal length lens), the fixture, etc., may also be considered to include any suitable driver as known in the art. Each driver typically includes an input to which a controller 122 is communicatively coupled, such that the controller 122 is capable of generating one or more control signals (e.g., trigger signals, etc.). The control signals may be sent to inputs of one or more drivers associated with one or more components of the apparatus 100. In this manner, components such as the laser source 104, first positioner 106, second positioner 108, third positioner 110, lens actuator, scan lens 112 (if provided as a variable focal length lens), fixture, etc. are responsive to control signals generated by the controller 122.

[0076] Although not shown, one or more additional controllers (e.g., component-specific controllers) may optionally be communicatively coupled to inputs of drivers communicatively coupled to (and associated with) components such as laser source 104, first positioner 106, second positioner 108, third positioner 110, lens actuator, scan lens 112 (if provided as a variable focal length lens), fixture, etc. In this embodiment, each component-specific controller may be communicatively coupled to controller 122 and capable of generating one or more control signals (e.g., trigger signals, etc.) in response to one or more control signals received from controller 122. The one or more control signals may then be transmitted to inputs of the driver communicatively coupled thereto. In this embodiment, the component-specific controller may be operable in a manner similar to that described with respect to controller 122.

[0077] In other embodiments where one or more component-specific controllers are provided, a component-specific controller associated with a component (e.g., laser source 104) may be communicatively coupled to a component-specific controller associated with a component (e.g., first positioner 106, etc.). In this embodiment, one or more of the component-specific controllers may generate one or more control signals (e.g., trigger signals, etc.) in response to one or more control signals received from one or more other component-specific controllers.

[0078] III. Example Embodiments of the First Positioner A. AOD System Embodiments 2, when the first positioner 106 is provided as an AOD system (e.g., as described above), the first positioner 106 can be operated to implement a beam path deflection scheme in which the zero-order beam path 200 is located between the first primary angular range 116a and the second primary angular range 116b. In this deflection scheme, the first positioner 106 can be operated or driven to deflect the beam path 114 within the first primary angular range 116a or the second primary angular range 116b by reversing the phase of an applied RF drive signal (e.g., in response to an applied RF drive signal having a particular frequency). In the illustrated embodiment, the beam trap 202 is positioned to absorb laser energy propagating along the beam path 200.

[0079] 3, when the first positioner 106 is provided as an AOD system (e.g., as described above), the first positioner 106 can be operated to implement a beam path deflection scheme in which the zero-order beam path 300 is not located between the first primary angular range 116a and the second primary angular range 116b. In this deflection scheme, the first positioner 106 can be operated or driven to deflect the incident beam path 114 within the first primary angular range 116a or the second primary angular range 116b by varying the frequency of an applied RF drive signal (e.g., in response to an applied RF drive signal having a particular frequency) without reversing the phase of the applied RF drive signal. In the illustrated embodiment, the beam trap 202 is positioned to absorb laser energy propagating along the beam path 300.

[0080] In any of the embodiments described above with respect to Figures 2 and 3, the first positioner 106 may be provided as a single-axis AOD system or a multi-axis AOD system. Depending on the configuration of the AOD within the AOD system (e.g., as described above), the AOD may be characterized as a longitudinal mode AOD or a shear mode AOD and may be capable of diffracting a linearly or circularly polarized laser energy beam. Thus, depending on the wavelength of the laser energy beam and the material forming the AO cells of the AODs in the AOD system, the AODs within the AOD may be oriented so that the diffraction axis of the AO cells within the AOD is parallel or perpendicular (or at least substantially parallel or perpendicular) to the plane of polarization of the laser energy beam incident thereon. For example, if the wavelength of the laser energy beam is in the ultraviolet or visible green region of the electromagnetic spectrum and the AO cells of the AOD are formed from a material such as quartz, the AOD may be oriented so that the diffraction axis of the AO cells is perpendicular (or at least substantially perpendicular) to the plane of polarization of the incident laser energy beam. In another example, if the wavelength of the laser energy beam is in the so-called mid-wavelength infrared or long-wavelength infrared region of the electromagnetic spectrum (i.e., wavelengths ranging from 3 μm (or thereabouts) to 15 μm (or thereabouts)), and the AO cell of the AOD is formed from a material such as crystalline germanium, the AOD can be oriented so that the diffraction axis of the AO cell is parallel (or at least substantially parallel) to the plane of polarization of the incident laser energy beam.

[0081] 4, the multi-axis AOD system may be provided as a multi-cell multi-axis AOD system 400 including a first AOD 402 and a second AOD 404. Either of the first AOD 402 and the second AOD 404 may be provided by the methods described above. The first AOD 402 is positioned and operable to rotate an incident laser energy beam (e.g., propagating along beam path 114) by any angle (e.g., measured relative to beam path 114 incident on the first AOD 402) about a first axis of rotation within a first angular range (also referred to herein as "first AOD angular range 406") to transmit a primary beam propagating along a deflected beam path 114'. Similarly, the second AOD 404 is positioned and operable to rotate the incident laser energy beam (which may be a zero-order beam, a first-order beam, etc., or any combination thereof) transmitted through the first AOD 402 by any angle (e.g., measured relative to the beam path 114' incident on the second AOD 404) within a second angular range (also referred to herein as the "second AOD angular range 408") about a second rotation axis to transmit the first-order beam propagating along the deflected beam path 114". As will be appreciated, each of the beam path 114' and the beam path 114" represents a specific example of a path along which a laser energy beam may propagate. Accordingly, each of the beam path 114' and the beam path 114" may also be collectively referred to herein as the "beam path 114".

[0082] Typically, the second AOD 404 is oriented relative to the first AOD 402 such that the second axis of rotation is different from the first axis of rotation. For example, the second axis of rotation may be orthogonal to the first axis of rotation or oblique to the first axis of rotation. However, in other embodiments, the second AOD 404 is oriented relative to the first AOD 402 such that the second axis of rotation is parallel (or at least substantially parallel) to the first axis of rotation. In this case, one or more optical components may be positioned in the beam path 114′ to rotate the plane of polarization of the first AOD 402 (e.g., by 90 degrees or thereabouts) so that, when projected onto the second AOD 404, the plane of polarization of the first AOD 402 is rotated (e.g., by 90 degrees or thereabouts) relative to the direction of the plane of polarization of the second AOD 404. See, for example, International Publication No. WO2019 / 060590A1 for examples of how the deflection plane may be rotated as described above.

[0083] In general, the AO cells in the first AOD 402 are formed from materials that may be the same as or different from the AO cells in the second AOD 404. Furthermore, the type of acoustic waves (i.e., shear mode or longitudinal mode) that the first AOD 402 uses to polarize the incident laser energy beam may be the same as or different from the type of acoustic waves that the second AOD 404 uses to polarize the incident laser energy beam.

[0084] It will be appreciated that the AOD system 400 may be operated at any one time so that only the first AOD 402 generates a primary beam, or only the second AOD 404 generates a primary beam, or both the first AOD 402 and the second AOD 404 generate primary beams. Thus, the deflection of the beam path 114 caused by the first positioner 106 can be considered to result solely from the deflection obtained from beam path 114′, or solely from the deflection obtained from beam path 114″, or from the superposition of the deflections obtained from beam paths 114′ and 114″. Similarly, the primary angular range 116 can be considered to be solely the first AOD angular range 406, or solely the second AOD angular range 408, or the superposition of the first AOD angular range 406 and the second AOD angular range 408. Finally, the primary angular range 116 shown in FIG. 4 may be either the first primary angular range 116a or the second primary angular range 116b shown in either FIG. 2 or FIG.

[0085] 4, the zero-order beam from the first AOD 402 is transmitted to the second AOD 404, and the zero-order beam transmitted through the second AOD 404 may be absorbed in a beam trap (not shown). However, in other embodiments, the zero-order beam transmitted through the first AOD 402 may be blocked (e.g., by a beam trap or mirror (not shown) positioned between the first AOD 402 and the second AOD 404) to prevent laser energy propagating along the zero-order beam path from the first AOD 402 from being transmitted to the second AOD 404. Blocking the zero-order beam as described above may be preferable if the first AOD 402 has a relatively high diffraction efficiency and can be left on for the entire duration of the laser pulse. However, because the second AOD 404 compensates for the first AOD 402, the heat load on the two AODs is often relatively equal, so keeping the first AOD 402 on for the entire pulse duration may increase the average heat load on the first AOD 402 and the second AOD 404. Increasing the heat load on the AODs may potentially cause undesirable beam distortion (e.g., due to thermal lensing).

[0086] Notwithstanding the above, directing the zero-order beam to the second AOD 404 may assist in maintaining the AO cell of the second AOD 404 at the same temperature (or close to the same temperature) as the AO cell of the first AOD 402. Directing the zero-order beam to the second AOD 404 may assist in maintaining a relatively uniform temperature distribution within the region of the AO cell of the second AOD 404 through which the laser energy beam passes during operation of the second AOD 404. This may eliminate or reduce undesirable effects such as thermal lensing and beam drift during operation of the second AOD 404. In view of the above, directing the zero-order beam to the second AOD 404 may be particularly advantageous when the material forming the AO cell has a relatively high absorption coefficient at the wavelength of the laser energy beam being deflected. For example, crystalline germanium is known to have a relatively high absorption coefficient at wavelengths in the mid- to long-infrared region of the electromagnetic spectrum (e.g., compared to the absorption coefficient of quartz at wavelengths in the near-UV to visible region of the electromagnetic spectrum).

[0087] When the first positioner 106 is provided as an AOD system such as AOD system 400, the first positioner 106 may include one or more other additional optical components, such as a beam trap, a beam expander, a beam shaper, an aperture, a filter, a collimator, a lens, a mirror, a phase retarder, a polarizer, etc., or any combination thereof, as needed.

[0088] B. Embodiments Generally Relating to Beam Dump Systems In one embodiment, the first positioner 106 includes one or more beam dump systems that capture and absorb (i.e., trap) laser energy propagating from the AOD along an undesired beam path. Conventionally, undesired laser energy propagating from the AOD is diverted using pick-off mirrors that reflect the laser energy (e.g., at their reflective surfaces) into a remote beam trap. The laser energy may be reflected directly from the pick-off mirrors into the beam trap, or it may be reflected indirectly into the beam trap via one or more additional relay mirrors. The pick-off mirrors and the beam traps (and the relay mirrors therebetween) comprise a beam dump system.

[0089] Referring to FIG. 5 , the first positioner 106 may include a beam dump system 500 (also referred to herein as the “first beam dump system”) disposed at the optical output side of the first AOD 402. The first AOD 402 typically operates to diffract an incident laser energy beam to generate a zeroth-order beam and a first-order beam that propagate from the first AOD 402 along a zeroth-order beam path 300 and a first-order beam path 114′, respectively. Often, one or more beams of other diffraction orders are also generated. Each of these beams may propagate from the first AOD 402 along one or more other beam paths, collectively labeled 502 in FIG. 5 . The beam dump system 500 is configured to trap laser energy propagating along any of the beam paths, such as beam path 502, while allowing laser energy propagating along the zeroth-order beam path 300 and the first-order beam path 114′, respectively, to continue propagating (e.g., to the second AOD 404). In other embodiments, the beam dump system 500 may be configured to trap laser energy propagating along the zero-order beam path 300 (i.e., to prevent the laser energy from propagating to the second AOD 404).

[0090] 6, the first positioner 106 may include a beam dump system 600 (also referred to herein as a "second beam dump system") located at the optical output side of the second AOD 404. The second AOD 404 typically operates to diffract an incident laser energy beam (e.g., propagating along the first order beam path 114' from the first AOD 402 and, optionally, propagating along the zero order beam path 300 from the first AOD 402). During operation of the second AOD 404, an incident laser energy beam propagating along beam path 114' is diffracted to generate a first order beam that propagates from the second AOD 404 along first order beam path 114". Similar to the first AOD 402, one or more beams of other diffraction orders may also be generated during operation of the second AOD 404. Each of these beams may propagate from the second AOD 404 along one or more other beam paths, collectively labeled 602 in FIG. 6. In addition, at least a portion of the laser energy beam propagating from the first AOD 402 along zero order beam path 300 may propagate from the second AOD 404 along zero order beam path 300. The beam dump system 600 is configured to trap laser energy propagating along beam paths such as beam paths 300 and 602, while continuing to propagate laser energy propagating along first order beam path 114" (e.g., to the second positioner 108).

[0091] In one embodiment, the first positioner 106 includes both the first beam dump system 500 and the second beam dump system 600. However, in other embodiments, the first positioner 106 may include the first beam dump system 500 but not the second beam dump system 600, or may include the second beam dump system 600 but not the first beam dump system 500. Although the first beam dump system 500 and the second beam dump system 600 (each collectively referred to herein as a "beam dump system") are described herein as being incorporated within the first positioner 106 provided as a multi-cell, multi-axis AOD system 400, it will be understood that any number of the beam dump systems described herein may be incorporated into a first positioner 106 that includes only one AOD, or may be used in conjunction with other optical components such as prisms, lenses, galvanometer mirror systems, fast steering mirror systems, etc., or any combination thereof.

[0092] i. Example of an embodiment of a beam dump system In one embodiment, the pick-off mirrors and the beam trap of the beam dump system (and the relay mirrors therebetween) are provided as physically separate components that are each separately mounted and attached (e.g., by screws, adhesives, clamps, etc., or any combination thereof) to a common optical breadboard or the like. While this provides a flexible solution, alignment between these components can be a difficult and time-consuming process.

[0093] To address the potential problems associated with separate beam dump system components, other beam dump system embodiments may integrate pickoff mirrors, beam traps, and intervening relay mirrors (pre-aligned as needed) into a common package. Such beam dump systems (also referred to herein as "integrated beam dump systems") can be easily incorporated into a beam path assembly by any suitable method known in the art. The only alignment required is to align the optical input of the integrated beam dump system with the undesired beam path location.

[0094] In an example embodiment, the integrated beam dump system may include one or more separately provided pickoff mirrors, one or more beam traps, and, optionally, one or more relay mirrors between the pickoff mirrors and the beam traps, all of which are attached (e.g., by screws, adhesives, clamps, etc., or any combination thereof) to a common structure such as an optical breadboard. As known in the art, an optical breadboard is a generally planar structure formed from materials such as steel, brass, aluminum or aluminum alloys, or carbon fiber reinforced polymer composites, which provides a flat surface to which optical components can be attached (e.g., by screws, adhesives, clamps, etc., or any combination thereof). The optical breadboard is then mounted within the beam path assembly of the laser processing apparatus 100.

[0095] In other example embodiments, the common structure to which the separate components are attached may be a frame (e.g., formed from a material such as steel, brass, aluminum or aluminum alloy, copper or copper alloy, or carbon fiber reinforced polymer composite), having multiple surfaces (at least two of which are non-coplanar) to which different ones of the separate components may be attached (e.g., by screws, adhesives, clamps, or the like, or any combination thereof). The frame may be fabricated by any suitable or desired method known in the art, such as, for example, CNC milling, casting, welding, vacuum bagging, compression molding, or the like, or any combination thereof.

[0096] In other example embodiments, the frame may be provided or processed in a manner to form one or more reflective surfaces (e.g., suitable to function as a pick-off mirror, a relay mirror, or any combination thereof), one or more light-absorbing surfaces or structures (e.g., suitable to function as a beam trap or part thereof), or the like, or any combination thereof. For example, if the frame is formed from a metallic material such as steel, brass, aluminum or an aluminum alloy, copper or a copper alloy, or the like, the surface of the frame may be ground and / or polished (e.g., chemically, mechanically, or any combination thereof) to form a reflective surface. In other examples, regardless of the material from which the frame is formed, the surface of the frame may be coated (e.g., via an electrolytic plating process, an electroless plating process, a vacuum deposition process, or the like, or any combination thereof) with a material that is reflective to the wavelength of light of the laser energy beam incident on that surface. Examples of materials that may be coated on the frame to form a reflective surface include aluminum, gold, silver, copper, or the like, or any combination thereof.

[0097] In another example, if the frame is formed from a metallic material such as steel, aluminum or an aluminum alloy, copper or a copper alloy, etc., the surface of the frame can be etched, roughened, oxidized, anodized, etc. to form a surface or other structure that is suitably absorbing of the incident laser energy beam (e.g., suitable for functioning as or part of a beam trap). In another example, regardless of the material from which the frame is formed, the surface of the frame can be coated (e.g., via an electrolytic plating process, an electroless plating process, a vacuum deposition process, a painting process, etc., or any combination thereof) with a material that is suitably absorbing of the laser energy beam incident on that surface.

[0098] Depending on one or more factors, such as the configuration of the beam trap and the power and wavelength of the laser energy beam absorbed by the beam trap, the absorption of laser energy may cause the beam trap to heat up in an undesirable manner. Therefore, the integrated beam dump system may include one or more cooling systems thermally coupled to the beam trap and configured to remove heat from the beam trap. Examples of suitable cooling systems include heat sinks, heat pipes, Peltier heat pumps, water blocks, or the like, or any combination thereof. In one embodiment, the one or more cooling systems may be thermally coupled to the optical breadboard or frame. In another embodiment, the one or more cooling systems may be integrated into or mechanically coupled to the optical breadboard or frame.

[0099] ii. Example Embodiments of Integrated Beam Dump Systems Referring to FIG. 7 , an integrated beam dump system such as integrated beam dump system 700 can include a frame 702 formed from a material such as steel, brass, aluminum or aluminum alloy, copper or copper alloy, etc., or any combination thereof. Frame 702 can be formed by any suitable or desired process known in the art (e.g., CNC milling, casting, welding, etc., or any combination thereof) to form multiple surfaces such as surfaces 704, 706, 708, 710, 712, 714, and 716. Generally, surfaces 704, 706, and 708 are provided as reflective surfaces, and surfaces 710, 712, 714, and 716 are provided as absorbing surfaces, as needed. For example, as described in detail with respect to FIGS. 8 and 9 , surfaces 704 and 706 can function as pickoff mirrors, surface 708 can function as a relay mirror, and surfaces 710, 712, 714, and 716 can be positioned relative to one another to form a beam trap 718. In this manner, surfaces 704 and 706 can redirect laser energy propagating along an undesired beam path toward surface 708, which reflects the diverted laser energy toward beam trap 718.

[0100] Surfaces 704, 706, and 708 can be made reflective during or after the formation of frame 702. For example, after frame 702 is formed, surfaces 704, 706, and 708 can be made reflective by subjecting the area of ​​frame 702 where one or more of surfaces 704, 706, and 708 are formed (e.g., as described above), or by coating one or more of surfaces 704, 706, and 708 with a suitable reflective material (e.g., as described above), or any combination thereof.

[0101] Surfaces 710, 712, 714, and 716 can be made absorptive during or after formation of frame 702. For example, frame 702 can be formed so that surfaces 704, 706, 708, 710, 712, 714, and 716 are reflective, and then surfaces 704, 706, and 708 can be masked to prevent subsequent processes applied to frame 702 (e.g., one or more etching, roughening, oxidation, anodizing, coating, etc., or any combination thereof) from rendering surfaces 704, 706, and 708 optically absorptive. Examples of masking materials that can be used to mask surfaces 704, 706, and 708 include tapes, waxes, lacquers, masking resins, and the like, as known in the art. After surfaces 704, 706, and 708 are appropriately masked, surfaces 710, 712, 714, and 716 may be subjected to one or more treatments (e.g., as described above) to render them optically absorptive. The masking material may then be removed from surfaces 704, 706, and 708, which are still reflective.

[0102] In one embodiment, frame 702 can be formed by machining (e.g., by CNC milling) a block (e.g., formed from aluminum or aluminum oxide), and the resulting faces of frame 702 can be anodized to form an anodized layer thick enough to at least partially (or at least substantially) absorb an incident laser energy beam. Generally, the minimum thickness of the anodized layer necessary to provide the desired optical absorption of laser energy depends on the wavelength of the laser energy being absorbed. For example, an anodized layer formed to a thickness of 45 μm or greater has been found to be sufficient to adequately absorb laser energy at a wavelength of 9.4 μm. After anodizing frame 702, the areas of frame 702 where one or more of faces 704, 706, and 708 are formed may be ground and / or polished to remove the anodized layer and form a suitably reflective surface. Alternatively, surfaces 704, 706, and 708 may be masked (e.g., as described above) before anodizing frame 702, and the masking material may be removed after the unmasked portions of frame 702 (e.g., surfaces 710, 712, 714, and 716) have been suitably anodized.

[0103] Referring to FIG. 8 , surface 704 may function as a pick-off mirror that redirects laser energy propagating along an undesired beam path (e.g., beam path 800 propagating from the first AOD 402 or the second AOD 404) toward surface 708. Surface 708 may function as a relay mirror that reflects laser energy reflected from surface 704 to beam trap 718 (e.g., to surface 716) where the laser energy is absorbed. While FIG. 8 shows beam path 800 as terminating at surface 716 (thereby suggesting that all laser energy propagating along beam path 800 is absorbed), it will be understood that some laser energy may be reflected from surface 716. In this case, the laser energy reflects from surface 716 to surface 712, and the remaining energy is either completely absorbed or partially reflected back to surface 716 and at least partially absorbed therein.

[0104] Similarly, with reference to FIG. 9 , surface 706 may function as a pick-off mirror to divert laser energy propagating along an undesired beam path (e.g., beam path 900 propagating from the first AOD 402 or the second AOD 404) to surface 708. Surface 708 may function as a relay mirror to reflect laser energy reflected from surface 704 toward beam trap 718 (e.g., toward surface 710) where the laser energy is absorbed. While FIG. 9 illustrates beam path 900 as terminating at surface 710 (thereby suggesting that all laser energy propagating along beam path 900 is absorbed), it will be understood that some laser energy may be reflected from surface 710. In this case, the laser energy reflects from surface 710 to surface 714, where the remaining laser energy is either completely absorbed or partially reflected back to surface 710 and at least partially absorbed by surface 710.

[0105] Returning to FIG. 7 , frame 702 may further include aperture 720, which serves as an optical input for integrated beam dump system 700. As shown, aperture 720 is positioned and sized to allow laser energy propagating along a beam path from first AOD 402 or second AOD 404 (e.g., along beam path 114 or 300 as shown in FIG. 7 , or along another beam path such as beam path 800 or 900 as shown in FIG. 8 or FIG. 9 , respectively, or along any combination thereof) to pass therethrough. Frame 702 may further include apertures 722 and 724, which each serve as an optical output for integrated beam dump system 700. That is, aperture 722 is positioned and sized to allow laser energy propagating along beam path 114 to pass therethrough. Similarly, aperture 724 is positioned and sized to allow laser energy propagating along beam path 300 to pass therethrough.

[0106] 10 , an integrated beam dump system such as integrated beam dump system 1000 may include a frame 1002 formed from a material such as steel, brass, aluminum or an aluminum alloy, copper or a copper alloy, or the like, or any combination thereof. Frame 1002 may be formed by any suitable or desired process known in the art (e.g., as described above with respect to frame 702) to form a plurality of surfaces, such as surfaces 1004, 1006, 1008, 1010, 1012, 1014, 1016, 1018, and 1020. Generally, surfaces 1004, 1006, 1008, 1010, and 1012 are provided as reflective surfaces, and surfaces 1014, 1016, 1018, and 1020 are provided as light-absorbing surfaces. Any of surfaces 1004, 1006, 1008, 1010, and 1012 may be configured in any manner (e.g., the same or similar manner as described with respect to surfaces 704, 706, and 708) to suitably reflect an incident laser energy beam. Similarly, any of surfaces 1014, 1016, 1018, and 1020 may be configured in any manner (e.g., the same or similar manner as described with respect to surfaces 710, 712, 714, and 716) to suitably absorb an incident laser energy beam. Thus, as described in more detail with respect to Figures 11-14, surfaces 1004, 1006, and 1008 may function as pickoff mirrors, surfaces 1010 and 1012 may function as relay mirrors, and surfaces 1014, 1016, 1018, and 1020 may be arranged relative to one another to form a beam trap 1022. In this manner, surfaces 1004, 1006, and 1008 can divert laser energy propagating along undesired beam paths. In particular, surface 1004 is configured to reflect incident laser energy directly toward beam trap 1020, and surfaces 1006 and 1008 are configured to reflect incident laser energy toward surfaces 1010 and 1012, respectively. Surfaces 1010 and 1012 are then each configured to reflect the diverted laser energy toward beam trap 1022.

[0107] 11 , surface 1004 can function as a pick-off mirror to redirect laser energy propagating along an undesired beam path (e.g., beam path 1100 propagating from the first AOD 402 or the second AOD 404) toward surface 1014. While FIG. 11 shows beam path 1100 as terminating at surface 1014 (thereby suggesting that all of the laser energy propagating along beam path 1100 is absorbed), it will be understood that some laser energy may be reflected from surface 1014. In this case, the laser energy reflects from surface 1014 to surface 1018, and the remaining laser energy is either completely absorbed at surface 1018 or partially reflected back to surface 1014 and at least partially absorbed by surface 1014.

[0108] 12 , surface 1008 can function as a pick-off mirror to redirect laser energy propagating along an undesired beam path (e.g., beam path 1200 propagating from the first AOD 402 or the second AOD 404) toward surface 1014. While FIG. 12 shows beam path 1200 as terminating at surface 1016 (thereby suggesting that some of the laser energy propagating along beam path 1200 is reflected from surface 1014 and that all of the laser energy so reflected propagating along beam path 1200 is absorbed at surface 1016), it will be understood that some laser energy may be reflected from surface 1016. In this case, the laser energy will most likely reflect from surface 1016 to surface 1020, with the remaining laser energy either being completely absorbed at surface 1020 or being partially reflected back to surface 1016 and at least partially absorbed at surface 1016.

[0109] 13, surface 1006 may act as a pick-off mirror that redirects laser energy propagating along an undesired beam path (e.g., beam path 1300 propagating from the first AOD 402 or the second AOD 404) toward surface 1010. Surface 1010 may act as a relay mirror that reflects laser energy reflected from surface 1004 toward beam trap 1022 (e.g., toward surface 1016) where the laser energy is absorbed. While FIG. 13 shows beam path 1300 as terminating at surface 1016 (which suggests that all of the laser energy propagating along beam path 1300 is absorbed), it will be understood that some laser energy may be reflected from surface 1016. In this case, laser energy reflects from surface 1016 to surface 1020 and the remaining laser energy is either completely absorbed by surface 1020 or partially reflected back to surface 1016 and at least partially absorbed by surface 1016 .

[0110] 14 , surface 1008 may act as a pick-off mirror that redirects laser energy propagating along an undesired beam path (e.g., beam path 1400 propagating from the first AOD 402 or the second AOD 404) toward surface 1012. Surface 1012 may act as a relay mirror that reflects laser energy reflected from surface 1008 toward beam trap 1022 (e.g., toward surface 1016) where the laser energy is absorbed. While FIG. 14 shows beam path 1400 as terminating at surface 1016 (which suggests that all of the laser energy propagating along beam path 1400 is absorbed), it will be understood that some laser energy may be reflected from surface 1016. In this case, laser energy reflects from surface 1016 to surface 1020 and the remaining laser energy is either completely absorbed by surface 1020 or partially reflected back to surface 1016 and at least partially absorbed by surface 1016 .

[0111] Returning to FIG. 10 , the frame 1002 may further include an aperture 1024 that serves as an optical input for the integrated beam dump system 1000. As shown, the aperture 1024 is positioned and sized to allow laser energy propagating along a beam path from the first AOD 402 or the second AOD 404 (e.g., along beam path 114 as shown in FIG. 10 , or along other beam paths such as beam paths 1100, 1200, 1300, or 1400 as shown in FIGS. 11 , 12 , 13 , or 14 , respectively, or along any combination thereof) to pass therethrough. The frame 1002 may further include an aperture 1026 that serves as an optical output for the integrated beam dump system 1000. That is, the aperture 1026 is positioned and sized to allow laser energy propagating along beam path 114 to pass therethrough. In the integrated beam dump system 1000, the path of the zero-order beam path 300 (e.g., propagating from the first AOD 402 or the second AOD 404) is directed to and sent to the beam trap 1022. In this case, the zero-order beam path 300 may be represented by, for example, beam path 1200 or 1300.

[0112] From the above description of integrated beam dump systems 700 and 1000, it will be understood that the surfaces provided by frames 702 and 1002 define interior regions through which laser energy may propagate toward the respective beam traps. For example, the surface provided by frame 702 defines interior region 726, and the surface provided by frame 1002 defines interior region 1028. To prevent or minimize the ingress of undesirable dust or other particles or objects into these interior regions, either integrated beam dump system 700 or 1000 may optionally include one or more plates spanning the interior regions. For example, integrated beam dump system 700 may include a first plate coupled to frame 702 (e.g., at a first side thereof). 728a second plate coupled (e.g., by screws, adhesive, clamps, etc., or any combination thereof) to frame 702 (e.g., on a second side thereof opposite the first side); 730 (shown by dashed lines in FIG. 7 ), or a combination thereof. Similarly, the integrated beam dump system 1000 may include a first plate 1030 coupled to the frame 1002 (e.g., at a first side thereof), a second plate 1032 (shown by dashed lines in FIG. 10 ) coupled to the frame 1002 (e.g., at a second side opposite the first side thereof) (e.g., by screws, adhesive, clamps, etc., or any combination thereof), or a combination thereof. With respect to the integrated beam dump system 1000, although the frame 1002 is described above as providing the surface 1008, the surface 1008 may instead be provided by a block (e.g., block 1034) coupled to the first plate 1030 (e.g., by screws, adhesive, clamps, etc., or any combination thereof).

[0113] In one embodiment, any of the above plates coupled to the frame of integrated beam dump system 700 or 1000 may be formed from a thermally conductive material (e.g., steel, brass, aluminum or aluminum alloy, copper or copper alloy, etc., or any combination thereof) to allow heat to be removed from the associated beam trap (i.e., beam trap 718 or 1022). In other embodiments, one or more cooling systems (e.g., heat sinks, heat pipes, Peltier heat pumps, water blocks, etc., or any combination thereof) may be coupled to or fully or partially integrated with one or more of plates 728, 730, 1030, 1032.

[0114] C. Embodiments Generally Relating to Phase Retarder Depending on the type of AOD included in first positioner 106, it may be desirable to rotate the plane of polarization (i.e., the plane in which the electric field oscillates) in the primary beam path passed through the AOD. Rotating the plane of polarization is desirable when the amount of RF drive power required to diffract a significant portion of the incident laser energy beam into the primary beam is highly dependent on the polarization state of the laser energy beam being deflected. Furthermore, if each AOD in a multi-cell AOD system includes AO cells made of the same material, and if each AOD in the multi-cell AOD system uses the same type of acoustic waves to deflect the incident laser energy beam, and if it is preferable to linearize the polarization state in a first beam passing through a first AOD in the multi-cell AOD system (e.g., the first AOD 402 in the multi-axis AOD system 400) and orient it in a particular direction relative to the diffraction axis of a second AOD in the multi-cell AOD system (e.g., the second AOD 404 in the multi-axis AOD system 400), it is similarly preferable to rotate the polarization state in a first beam passing through the second AOD relative to the polarization state in a first beam passing through the first AOD, just as the orientation of the second AOD is rotated relative to the orientation of the first AOD.

[0115] Examples of phase retarders that can be incorporated into first positioner 106 include one or more transmissive phase retarders (e.g., half-wave plates, quarter-wave plates, eighth-wave plates, etc., or any combination thereof), one or more reflective phase retarders (e.g., configured to provide a 180-degree phase shift, a 90-degree phase shift, etc., or any combination thereof), etc. In general, one or more phase retarders can be inserted into the beam path (e.g., primary beam path or otherwise) of the laser energy beam incident on the AOD as needed to align the plane of polarization of the linearly polarized laser energy beam incident on the AOD with the diffraction axis of the AO cell within the AOD. For example, one or more phase retarders can be positioned on beam path 114′ between the first and second AODs to align the plane of polarization of the linearly polarized laser energy beam exiting the first AOD and entering the second AOD with the diffraction axis of the AO cell within the second AOD.

[0116] D. Embodiments Generally Relating to Compensating for Wavefront Distortion In many cases, transmissive optical components absorb a portion of the light incident on them. When the incident light is a high-power laser energy beam, the absorbed light heats the material comprising the transmissive optical component. Sometimes, when a laser energy beam has a non-uniform spatial intensity profile (e.g., similar to a Gaussian spatial intensity profile), different regions of the beam heat different parts of the transmissive optical component to different temperatures. For example, the central region of a beam with a Gaussian spatial intensity distribution heats one region of the transmissive optical component more than the peripheral regions of the beam. Because the refractive index of many materials comprising transmissive optical components changes with temperature (known as the thermo-optic effect), the wavefront of a high-power laser energy beam is modified as it passes through a transmissive optical component. In addition, relatively hot regions of a transmissive optical component can expand (as a result of thermal expansion), and such expansion can cause the shape of the transmissive optical component to approximate that of a lens. Also, changes in refractive index can occur due to thermally induced mechanical stresses within the transmissive optical component (known as the photoelastic effect). As used herein, the differential heating of different portions of a transmissive optical component may also be referred to as “differential heating” of the transmissive optical component. Differential heating of a transmissive optical component can be achieved by means other than absorption of laser energy. For example, the transmissive optical component can be placed near a heat source. Transmissive optical components such as EO or AO cells may be differentially heated, for example, when the system in which they are incorporated is operated. As known in the art, differential heating of a transmissive optical component can cause differential changes in the refractive index within the transmissive optical component, an effect also known as “thermal lensing.” Thermal lensing can undesirably focus, defocus, or distort the wavefront of a laser energy beam as it propagates along the beam path 114 and passes through the beam path assembly.

[0117] One way to address the potentially detrimental effects associated with thermal lensing is to use transmissive optical components that are substantially transparent to the wavelengths of light in the incident laser energy beam (i.e., to prevent thermal lensing). Another approach is to simply lower the power in the laser energy beam. However, these approaches may be difficult or impossible to implement if substantially transparent transmissive optical components do not exist or if the workpiece cannot be machined in the desired configuration using a relatively low-power laser energy beam. Therefore, according to embodiments described in more detail below, one or more optical components (referred to herein as “wavefront compensating optics”) may be positioned in the beam path 114 to compensate (i.e., fully or partially compensate) for wavefront distortions that may be caused by thermal lensing in one or more transmissive optical components of the beam path assembly.

[0118] In the embodiments described herein, the laser energy beam input to the transmissive optical component is typically axially symmetric (i.e., round, or at least substantially round), and the distortion caused by thermal lensing is often subject to one or more phase aberrations that are also axially symmetric. The phase aberrations induced in the wavefront of the laser energy beam can be described by Zernike polynomials combined with appropriately sized coefficients known in the art, namely:

number

[0119] In the discussion herein, the jth terms of the Zernike polynomials are described using the "fringe" (also known as "University of Arizona") numbering and normalization scheme. As the following terms are of most interest, they are explicitly shown in Table 1 below: [Table 1] The reader will note that these terms are radially symmetric and therefore Z j You will notice that (ρ,θ) does not depend on θ.

[0120] Through experiments conducted by applicant, it has been found that when a laser energy beam having a Gaussian spatial intensity profile heats the bulk transparent material of a transmissive optical component and causes thermal lensing within the transmissive optical component, the sign of the coefficient of the Z9 term is almost always opposite to the sign of the coefficient of the Z4 term, the magnitude of the coefficient of the Z9 term tends to be smaller than the magnitude of the coefficient of the Z4 term, and the ratio of the coefficient of the Z9 term to the Z4 term does not change appreciably as the amount of absorbed laser power changes. Therefore, independent and arbitrary correction of the coefficients of the Z4 and Z9 terms is not strictly necessary. These observations depend somewhat on the arbitrary choice of aperture size that defines the fringe Zernike polynomial fit, but aperture sizes from slightly less than to about twice the 4σ width of the laser energy beam are most useful (for a perfectly Gaussian beam, the 4σ width is 1 / e of the intensity at the peak). 2 (Equal to the full width of the beam at the off-center point of the

[0121] For example, FIG. 15 shows a set of graphs of experimental results illustrating how the coefficients of the Z4 and Z9 terms (and their ratio) vary with temperature for a bulk transparent material formed from a block of crystalline germanium (e.g., of the type used to form AO cells). In this case, a laser energy beam, generated from a CO2 laser source and having a wavelength ranging from 8 μm to 12 μm and a constant power, was irradiated onto the germanium block. As the block was irradiated with the laser energy beam, the temperature of the germanium block was varied by changing the temperature of the cooling water circulating around the germanium block. In this way, increasing the temperature of the cooling water increased the amount of laser energy absorbed by the germanium. From the graph shown in FIG. 15, it can be seen that the sign of the coefficient of the Z9 term (i.e., the data labeled "a9") is always opposite to the sign of the Z4 term (i.e., the data labeled "a4"), and the coefficient of the Z9 term tends to be smaller than the coefficient of the Z4 term. It can also be seen that the ratio of the coefficient of the Z9 term to the Z4 term (i.e., the data labeled "a9 / a4") does not change noticeably. It should be noted that the data in the graphs are based on observations when the aperture is approximately 1.6 times the 4σ width of the incident laser energy beam.

[0122] Although particular discussion of thermal lensing has been made above with respect to a bulk transparent material formed from crystalline germanium in combination with a high-power laser energy beam having a wavelength in the range of 8 μm to 12 μm, it will be appreciated that thermal lensing can also be observed in other bulk transparent materials used to form AO cells, such as tellurium dioxide (depending on one or more factors, e.g., the presence of impurities in the bulk transparent material, the power of the laser energy beam propagating through the bulk transparent material, the wavelength of the laser energy beam propagating through the bulk transparent material, etc., or any combination thereof). Furthermore, although particular discussion of thermal lensing has been made above with respect to a bulk transparent material used in AO cells, it will be appreciated that thermal lensing can also be observed in other transparent optical components, such as lenses, beamsplitters, prisms, dichroic filters, windows, wave plates, DOEs, ROEs, etc. (which may be coated, as needed, with one or more anti-reflective coatings, etc.) formed from bulk transparent materials. Therefore, the techniques for correcting or compensating for wavefront aberrations in a laser energy beam caused by thermal lensing can be generally applied to correct wavefront aberrations in a laser energy beam generated by a laser source 104, regardless of which transparent optical component the thermal lensing occurs in.

[0123] i. Example of an embodiment related to a wavefront adaptive optical component Having described the nature of aberrations in a laser energy beam that may be caused by thermal lensing, numerous embodiments of wavefront compensating optics that may be positioned in the beam path 114 to compensate for the aberrations are described below. In general, however, the wavefront compensating optics may be provided as one or more optical components, such as one or more lenses, mirrors, etc., or any combination thereof.

[0124] In one embodiment, the wavefront adaptive optics is a wavefront adaptive optic that is based on the fringe Zernike terms (e.g., Z4, Z9, Z 16The laser energy beam may be provided as a reflective optical component (e.g., a spherical mirror or a curved mirror) having a reflective surface with a shape characterized by a fringe Zernike term, where the coefficients of the fringe Zernike terms are selected to compensate for wavefront distortions in the laser energy beam. The shape of the reflective surface may be created by any suitable technique known in the art, such as by high-precision diamond turning of the mirror or by high-precision polishing of the mirror substrate using magnetorheological fluid (MRF) polishing.

[0125] In other embodiments, the wavefront adaptive optics may be modified to incorporate fringe Zernike terms (e.g., Z4, Z9, Z 16 The fringe Zernike term may be provided as a transmissive optical component (e.g., a spherical lens) having a reflective surface with a shape characterized by a coefficient of the Z9 term, such as a .alpha., ...

[0126] In yet other embodiments, the wavefront compensation optics may be provided as a combination of one or more reflective optical components (e.g., provided as described above) and one or more transmissive optical components (e.g., provided as described above), in which case any amount of compensation for the coefficients of the Z4 term may be realized on one or more surfaces of the one or more transmissive optical components, and any amount of compensation for the coefficients of the Z9 term may be realized on one or more surfaces of the one or more reflective optical components.

[0127] The reflective and transmissive optical components described above typically statically compensate for the effects caused by thermal lensing in the transmissive optical components and are therefore considered examples of "static wavefront adaptive optics." In other embodiments, the wavefront adaptive optics dynamically compensate for the effects caused by thermal lensing in the transmissive optical components and are therefore considered "dynamic wavefront adaptive optics." In this case, the dynamic wavefront adaptive optics may include one or more variable focal length lenses or lens assemblies, one or more deformable mirrors, and one or more transmissive spatial light modulators, either alone or in combination. Examples of types of deformable mirrors include segmented deformable mirrors (i.e., comprising independently actuable flat mirrors, which may be formed using MEMS technology as needed) and membrane deformable mirrors (i.e., comprising a reflective membrane that can be deformed mechanically, pneumatically, hydraulically, mechanically, etc., using methods known in the art). Additionally, the dynamic wavefront compensation optics may include fixed focal length lenses or lens assemblies that may be movable relative to one another, one or more shape-invariant mirrors, or the like, or any combination thereof (e.g., one or more zoom lenses).

[0128] Regardless of the type of optical components within the wavefront compensating optic, the wavefront compensating optic may be configured to compensate for (a) wavefront distortion accumulated by a laser energy beam at one or more locations in the beam path 114 "optically upstream" of the wavefront compensating optic (i.e., before propagating to the wavefront compensating optic), (b) wavefront distortion expected to be accumulated by a laser energy beam at one or more locations in the beam path 114 "optically downstream" of the wavefront compensating optic (i.e., after propagating from the wavefront compensating optic), or (c) a combination of (a) and (b). As used herein, the wavefront distortion accumulated by a laser energy beam before propagating to the wavefront compensating optic is also referred to as "actual wavefront distortion," and the wavefront distortion expected to be accumulated by a laser energy beam after propagating from the wavefront compensating optic is also referred to as "expected wavefront distortion."

[0129] a. Example of an embodiment related to a membrane-type deformable mirror 16 and 16A , in one embodiment, the membrane-type deformable mirror may be provided as a mirror 1600. Generally, the mirror 1600 includes a reflective surface 1602, a body 1604, and a pocket 1606 formed within the body 1604 (e.g., extending from the back surface of the body toward the reflective surface 1602). As such, the body 1604 may be characterized as including a relatively thin membrane region 1608 (e.g., formed between the reflective surface 1602 and the pocket 1606) and a relatively thick membrane region 1610 (e.g., surrounding the periphery of the pocket 1606). In one embodiment, the body 1604 may be formed from a material such as copper. Also, the reflective surface 1602 may be formed from the same material as the body 1604 (e.g., the body 1604 may be polished to form the reflective surface 1602). Alternatively, the reflective surface 1602 may be formed as a film or other coating formed on the body 1604.

[0130] The membrane region 1608 is configured to deform in response to changes in pressure within the pocket 1606. For example, referring to FIG. 17 , the mirror 1600 may be coupled to a base 1700 (e.g., via an adhesive, one or more welds, one or more clamps, one or more screws, or the like, or any combination thereof) to form a seal that extends along the periphery of the pocket 1606 (i.e., at the periphery of the pocket 1606, a peripheral region 1610 of the mirror 1600 is biased or sealed against a surface 1702 of the base 1700). The base 1700 includes perforations 1704 through which a fluid (e.g., air) can pass to pressurize or depressurize the pocket 1606, as is known in the art. When the pocket 1606 is not fully pressurized (e.g., when the pressure within the pocket 1606 is equal to the atmospheric pressure of the environment external to the pocket 1606), the reflective surface 1602 is substantially flat. When pocket 1606 is sufficiently pressurized (e.g., when the pressure within pocket 1606 is greater than the ambient pressure of the environment external to pocket 1606 by a predetermined threshold amount), the shape of reflective surface 1602 changes to have characteristics at least substantially identical to the wavefront distortion (actual wavefront distortion, predicted wavefront distortion, or any combination thereof) it is intended to compensate for. The geometry of membrane region 1608 changes the fringe Zernike terms (e.g., Z, Z, Z) that can be used to characterize the shape of reflective surface 1602 as it changes. 16 etc., or any combination thereof) is changed to compensate for wavefront distortions (actual wavefront distortions, predicted wavefront distortions, or any combination thereof) in the laser energy beam.

[0131] Generally, the pressure within pocket 1606 can be controlled by one or more control elements, such as a regulator (e.g., a constant pressure regulator or a variable pressure regulator), a control valve (e.g., an electronically controlled control valve responsive to one or more command signals output by controller 122 or another controller), or the like, or any combination thereof. The control element can introduce pressurized air into pocket 1606 (e.g., when laser source 104 is activated to generate a beam of laser energy to process the workpiece) and depressurize pocket 1606 (e.g., when laser source 104 is turned off or when laser source 104 is activated to generate a low-power beam of laser energy to facilitate alignment). In this case, a first end of a hose (e.g., a pneumatic hose, a hydraulic hose, etc.) is typically coupled to base 1700 in fluid communication with borehole 1704, and a second end of the hose (opposite the first end) is in fluid communication with the control element.

[0132] In one embodiment, apparatus 100 may include a laser power monitor, wavefront sensor, or the like, or any combination thereof, positioned and configured (e.g., at a location optically upstream relative to first positioner 106, or optically between first positioner 106 and second positioner 108, or optically downstream relative to second positioner 108, or the like, or any combination thereof) to generate measurement signals representative of the power (in the case of a laser power monitor), wavefront (in the case of a wavefront sensor), or the like, of the laser energy beam, as desired. The measurement signals may be output to controller 122, or to a component-specific controller associated with a regulator or control valve, or the like, or any combination thereof. Based on the received measurement signal, the controller (whether controller 122 or a component-specific controller associated with the regulator or control valve) can then output a control signal to the regulator and / or to the control valve to increase the pressure in pocket 1606 if the measurement signal indicates that the power of the laser energy beam has increased beyond, for example, a predetermined threshold power, or a predetermined wavefront, etc.

[0133] 16 and 16A , in one embodiment, the geometry of membrane region 1608 may be configured to ensure that the coefficients of one or more of the aforementioned fringe Zernike terms that can be used to characterize the shape of reflective surface 1602 have a linear (or at least substantially linear, or positively linear) dependence on the pressure in pocket 1606. Typically, the pressure in pocket 1606 may vary from 0 psi (or thereabouts) to 85 psi (or thereabouts). In other embodiments, the geometry of membrane region 1608 may be configured to ensure that the ratio (also referred to herein as the “compensation ratio”) between the coefficients of two or more of the aforementioned fringe Zernike terms that can be used to characterize the shape of reflective surface 1602 is within a predetermined range. For example, the geometry of membrane region 1608 can be configured to ensure that the compensation ratio of the coefficient of the Z9 term to the coefficient of the Z4 term (i.e., Z9:Z4) is in the range of −0.1 to −0.3 (e.g., −0.15 to −0.25, −0.18 to −0.23, −0.19 to −0.22, −0.19 to −0.21, etc.). This compensation ratio can vary within the ranges discussed above based on the pressure in pocket 1606, or can be constant (or at least substantially constant) regardless of the pressure in pocket 1606.

[0134] In view of the above, membrane region 1608 may be at least substantially circular when viewed in plan view (i.e., as shown in FIG. 16). A central portion of membrane region 1608 may have a first thickness t1 that is less than a second thickness t2 of a peripheral portion of membrane region 1608. Membrane region 1608 may be characterized as having a first radius r1, and the central portion of membrane region 1608 (i.e., the portion of membrane region 1608 having first thickness t1) may be characterized as having a second radius r2. First thickness t1 may be in the range of 0.8 mm (or thereabouts) to 0.3 mm (or thereabouts), e.g., 0.5 mm (or thereabouts). Second thickness t2 may be in the range of 1.0 mm (or thereabouts) to 2.0 mm (or thereabouts), e.g., 1.5 mm (or thereabouts). The first radius r1 can be in the range of 3.0 mm (or thereabouts) to 4.0 mm (or thereabouts), e.g., 3.5 mm (or thereabouts). The second thickness r2 can be in the range of 16.0 mm (or thereabouts) to 18.0 mm (or thereabouts), e.g., 17.0 mm (or thereabouts). Generally, the mirror 1600 itself can be characterized as having a third radius r3 that is greater than the second radius r2, and the peripheral region 1610 of the mirror 1600 has a third thickness t3 that is much greater than the second thickness t2. For example, the third radius r3 can be in the range of 24 mm (or thereabouts) to 26 mm (or thereabouts) (e.g., 25 mm or thereabouts). The third thickness t3 can be in the range of 8 mm (or thereabouts) to 10 mm (or thereabouts) (e.g., 10 mm or thereabouts). 16A illustrates small radii where two different surfaces meet (e.g., the radii within the dotted circled areas). These radii can reduce stress on the mirror substrate in these areas and reduce the likelihood of cracks forming and propagating to these areas. The presence of these radii is expected to result in a longer lifetime for the mirror 1600 in terms of the number of intermittent pressure cycles the mirror 1600 can withstand before permanently changing its shape.

[0135] In one embodiment, mirror 1600 is formed by obtaining a disk-shaped body (e.g., having at least a front and back surface that are substantially parallel to one another) and then machining the body from the back surface to form a pocket 1606 that includes a first cavity 1612 and a second cavity 1614 as shown. After forming pocket 1606, the front surface of the body is polished flat by one or more suitable techniques known in the art (e.g., flat grinding, diamond turning, magnetorheological finishing (MRF), etc., or any combination thereof). Optionally, the polished front surface may be coated with one or more highly reflective coatings suitable for reflecting a high-power laser energy beam.

[0136] In other embodiments, the mirror 1600 may be formed as described above, but rather than machining a body to form the first cavity 1612 and the second cavity 1614, only the first cavity 1612 need be formed to form the membrane region 1608. One or more stiffeners of any suitable shape, stiffness, thickness, and material may then be bonded to the face of the first cavity 1612 opposite the desired reflective surface 1602. The shape, stiffness, thickness, and material of the stiffeners may be selected to ensure that the membrane region 1608 deforms in a manner that compensates for wavefront distortions (actual wavefront distortions, predicted wavefront distortions, or any combination thereof) in the laser energy beam in the manner described above. In other embodiments, the mirror 1600 may be formed by attaching a deformable reflective membrane to a cylinder.

[0137] Configured as described above, the reflective surface 1602 of the membrane deformable mirror 1600 deforms to assume a shape (or range of shapes) that can be characterized by a combination of radially symmetric fringe Zernike polynomials, such as Z and Z. In other embodiments, the configuration of the membrane deformable mirror 1600 can be modified in any suitable manner known in the art so that, as the reflective surface 1602 deforms, the shape of the reflective surface 1602 can be suitably characterized by a single symmetric fringe Zernike polynomial (e.g., Z).

[0138] For example, referring to FIG. 18 , a membrane-type deformable mirror may be provided as mirror 1800. Mirror 1800 may be provided in a manner similar to that described with respect to mirror 1600. However, mirror 1800 may include multiple pockets, such as pockets 1802, 1804, and 1806. Pockets 1804 and 1806 are annular in shape and extend along the periphery of pocket 1802. Pockets 1802, 1804, and 1806 are radially spaced apart by a pair of annular ribs 1808 and 1810 extending from the back surface of deformable region 1608. Pockets 1802, 1804, and 1806 (and thus ribs 1808 and 1810) may be formed by any suitable method (e.g., by machining the back surface of the body that constitutes mirror 1800). In another embodiment, pockets 1802, 1804, and 1806 can be formed by first machining a single cavity in the back surface of the body that makes up mirror 1800, and then bonding annular ribs 1808 and 1810 to the back surface of deformable region 1608.

[0139] When mirror 1800 is suitably coupled to base 1700 (e.g., via adhesive, one or more welds, one or more clamps, one or more screws, etc., or any combination thereof), peripheral region 1610 as well as ribs 1808 and 1810 of mirror 1800 are biased or sealed against surface 1702 of base 1700. This results in the formation of multiple seals extending along the peripheries of pockets 1802, 1804, and 1806 (in which one or more ribs are biased or sealed against surface 1702 and peripheral region 1610 is biased or sealed against surface 1702).

[0140] 18 , the base 1700 includes a first perforation 1812, an optional second perforation 1814, and a third perforation 1816. The first perforation 1812 is in fluid communication with the pocket 1802, the second perforation 1814 (if present) is in fluid communication with the pocket 1804, and the third perforation 1816 is in fluid communication with the pocket 1806. Control of the pressure within the pocket 1802 and the pocket 1806 can be achieved using one or more hoses (e.g., connected to the first perforation 1812 and the third perforation 1816, respectively) and one or more control elements (e.g., connected to the hoses), as exemplarily described above. If present, the second perforation 1814 is open to the external environment such that the pocket 1804 is in fluid communication with the ambient environment outside the pocket 1804. In one embodiment, the pressure in pocket 1802 can be controlled independently of the pressure in pocket 1806. In other embodiments, the pressure in pocket 1802 can be controlled in a manner that is dependent on the pressure in pocket 1806, or the pressure in pocket 1806 can be controlled in a manner that is dependent on the pressure in pocket 1802. For example, first perforation 1812 can be coupled to a different control element than second perforation 1816. In other examples, first perforation 1812 and second perforation 1816 are commonly coupled to the same control element, which can pressurize or depressurize pocket 1802 relative to pocket 1806, or pressurize or depressurize pocket 1806 relative to pocket 1802, or which can commonly pressurize or depressurize pockets 1802 and 1806.

[0141] When pockets 1802 and 1806 are not sufficiently pressurized (e.g., when the pressure within pockets 1802 and 1806 is equal to the ambient pressure of the environment outside pockets 1802 and 1806), reflective surface 1602 is substantially flat. When pockets 1802 and 1806 are sufficiently pressurized (e.g., when the pressure in each of pockets 1802 and 1806 is greater than the ambient pressure of the environment outside pocket 1804 by a predetermined threshold amount), the portions of membrane region 1608 exposed by pockets 1802 and 1806 deform convexly (e.g., bow outward, away from surface 1702 of base 1700), which causes the portions of membrane region 1608 exposed by pocket 1804 to deform concavely (e.g., bow inward, toward surface 1702 of base 1700). In this case, the connections between membrane region 1608 and ribs 1808 and 1810 act as annular fulcrums, allowing membrane region 1608 to deform convexly at locations corresponding to pockets 1802 and 1806, and to deform membrane region 1608 concavely at locations corresponding to pocket 1804. The geometry of mirror 1800 can be configured to ensure that as the shape of reflective surface 1602 changes, the coefficient of the fringe Zernike term Z9 changes to compensate for spherical aberration in the laser energy beam.

[0142] 19, the membrane-type deformable mirror may be provided as mirror 1900. Mirror 1900 may be provided in a similar manner as described with respect to mirror 1800. However, mirror 1900 includes only a single annular rib 1906 that defines a pair of pockets (i.e., pocket 1902 and pocket 1904). Pocket 1904 is annular in shape and extends along the periphery of pocket 1902. Pockets 1902 and 1904 (and thus rib 1906) may be formed by any suitable method (e.g., as described with respect to mirror 1800).

[0143] When mirror 1900 is suitably coupled to base 1700 (e.g., via an adhesive, one or more welds, one or more clamps, one or more screws, etc., or any combination thereof), peripheral region 1610 and ribs 1906 of mirror 1900 are biased or sealed against surface 1702 of base 1700, thereby forming a number of seals that extend along the peripheries of pockets 1902 and 1904.

[0144] As shown in FIG. 19 , base 1700 includes first perforation 1908 and second perforation 1910. First perforation 1908 is in fluid communication with pocket 1902, and second perforation 1910 is in fluid communication with pocket 1904. Control of the pressure in pockets 1902 and 1904 can be achieved using one or more hoses (e.g., connected to first perforation 1908 and second perforation 1910, respectively) and one or more control elements (e.g., connected to the hoses), as exemplarily described above. In one embodiment, the pressure in pocket 1902 can be controlled independently of the pressure in pocket 1910, or the pressure in pocket 1910 can be controlled independently of the pressure in pocket 1902. In other embodiments, the pressure in pocket 1902 can be controlled in a manner that is dependent on the pressure in pocket 1904, or the pressure in pocket 1904 can be controlled in a manner that is dependent on the pressure in pocket 1902. For example, first perforation 1908 may be coupled to a different control element than second perforation 1910. In other examples, first perforation 1908 and second perforation 1910 are commonly coupled to the same control element, which can pressurize or depressurize pocket 1902 relative to pocket 1904, or pocket 1904 relative to pocket 1902, or which can commonly pressurize or depressurize pocket 1902 and pocket 1904.

[0145] When pockets 1902 and 1904 are not sufficiently pressurized (e.g., when the pressure within pockets 1902 and 1904 is equal to the ambient pressure of the environment outside pockets 1902 and 1904), reflective surface 1602 is substantially flat. When pockets 1902 and 1904 are sufficiently pressurized (e.g., when the pressure in each of pockets 1902 and 1904 is greater than the ambient pressure of the environment outside pockets 1902 and 1904 by a predetermined threshold amount), the portion of membrane region 1608 exposed by pockets 1902 and 1904 deforms convexly (e.g., bending outward away from surface 1702 of base 1700). In this case, the connection between membrane region 1608 and rib 1906 acts as an annular fulcrum, allowing membrane region 1608 to deform convexly as described above, and rib 1906 to deform membrane region 1608 concavely as described above. The geometry of the mirror 1900 may be configured to ensure that as the shape of the reflective surface 1602 changes, the coefficient of the fringe Zernike term Z9 changes to compensate for spherical aberration in the laser energy beam.

[0146] It will be appreciated that any of the above membrane-based deformable mirrors formed and constructed according to the above methods can be modified by any suitable method known in the art so that the shape of the deformed reflective surface 1602 can assume a variety of shapes, including but not limited to those defined by combinations of radially symmetric fringe Zernike polynomials described above. For example, the pockets of the membrane-based deformable mirrors described with respect to Figures 16, 18, and 19 are radially symmetric. If the membrane-based deformable mirror is modified to have a pocket that is not radially symmetric, the shape of the deformed reflective surface 1602 will not be radially symmetric.

[0147] ii. Embodiments generally relating to the use of optical relay systems Generally, wavefront aberrations caused by thermal lensing in a transmissive optical component occur at a specific location within the transmissive optical component, which can be approximated by a plane referred to herein as the "object plane" or "first plane." Ideally, the wavefront aberrations would be corrected at the object plane (i.e., the location where the wavefront aberrations were generated). However, this is usually physically impossible. Therefore, the object plane is reprojected onto another plane (referred to as the "image plane" or "second plane") located outside the transmissive optical component, and wavefront compensation optics are positioned at the image plane to compensate for the wavefront aberrations (e.g., by the methods described above).

[0148] Thus, in some embodiments, the beam path assembly may include an optical relay system disposed in the beam path 114 to relay or re-project the object plane to the wavefront adaptive optics (i.e., to place the image plane on the wavefront adaptive optics). The optical relay system may include any number of optical components (e.g., one or more mirrors, one or more lenses, etc., or any combination thereof), and the configuration and arrangement of the optical components within the optical relay system may be as known in the art to ensure that the size of the image of an object at the image plane is different from (e.g., larger or smaller than) the size of the actual object at the object plane.

[0149] a. Example of an embodiment related to an optical relay system 20 , an optical relay system such as optical relay system 2000 may include a first optical relay 2000 a, a second optical relay 2000 b, or a combination of first and second optical relays 2000 a, 2000 b. Optical relay system 2000 is incorporated into a beam path assembly that includes a wavefront compensation optic 2002 and one or both of first and second optical components 2004 a, 2004 b. Generally, at least one of first and second optical components 2004 a, 2004 b represents an optical component that may distort the wavefront of an incident laser energy beam due to thermal lensing (e.g., as described above). As such, the wavefront compensating optic 2002 may be configured to compensate for actual wavefront distortions accumulated by the laser energy beam as a result of thermal lensing in the first optical component 2004 a, or to compensate for expected wavefront distortions accumulated by the laser energy beam as a result of thermal lensing in the second optical component 2004 b, or a combination thereof. The wavefront compensating optic 2002 may be provided as a static wavefront compensating optic, a dynamic wavefront compensating optic, or the like, or any combination thereof. Generally, however, the wavefront compensating optic 2002 is transmissive to the laser energy beam incident thereon and is configured to transmit the incident laser energy beam.

[0150] As illustratively shown, each of the first optical relay 2000a and the second optical relay 2000b is provided as a pair of lenses. While FIG. 20 illustrates each of the first optical relay 2000a and the second optical relay 2000b as including no optical components between the lenses, in other embodiments, one or more optical components (e.g., mirrors, etc.) may be interposed between the lenses of one or both of the first optical relay 2000a and the second optical relay 2000b. The first optical relay 2000a is positioned and configured to relay an image of the laser energy beam at the first object plane (i.e., at a plane within the first optical component 2004a) to a first image plane (i.e., a plane located at or within the wavefront adaptive optic 2002) such that the image of the relayed laser energy beam at the first image plane is larger than the image at the first object plane. The second optical relay 2000b is positioned and configured to relay the image of the laser energy beam at the second object plane (i.e., at the plane at the wavefront compensating optic 2002 (which may be the same as the first image plane)) to a second image plane (i.e., a plane located at or within the second optical component 2004b) such that the image of the relayed laser energy beam at the second image plane is smaller than the image at the second object plane. In one embodiment, the first optical relay 2000a and the second optical relay 2000b are positioned and configured such that the size of the image of the relayed laser energy beam at the second image plane is the same as the size of the image of the laser energy beam at the first object plane. In other embodiments, the first optical relay 2000a and the second optical relay 2000b may be positioned and configured such that the size of the image of the relayed laser energy beam at the second image plane is larger or smaller than the size of the image of the laser energy beam at the first object plane.

[0151] 21 , the optical relay system 2000 described above includes one or both of the first optical component 2004 a and the second optical component 2004 b, but may be incorporated into a beam path assembly that includes a wavefront compensating optic 2100 instead of the wavefront compensating optic 2002. Similar to the wavefront compensating optic 2002, the wavefront compensating optic 2100 may be configured to compensate for actual wavefront distortions accumulated by a laser energy beam as a result of thermal lensing in the first optical component 2004 a, or to compensate for expected wavefront distortions accumulated by a laser energy beam as a result of thermal lensing in the second optical component 2004 b, or a combination thereof. Furthermore, the wavefront compensating optic 2100 may be provided as a static wavefront compensating optic, a dynamic wavefront compensating optic, or the like, or any combination thereof. However, in the illustrated embodiment, the wavefront compensating optic 2100 is configured to reflect (as opposed to transmit) the laser energy beam incident thereon. In this embodiment, the wavefront compensating optic 2100 may be a membrane-type deformable mirror provided by any suitable method (exemplary as described above).

[0152] According to the exemplary embodiment shown in FIGS. 20 and 21, the first optical relay 2000a and the second optical relay 2000b are provided as completely separate components. That is, the first optical relay 2000a and the second optical relay 2000b do not physically incorporate any common components (e.g., lenses, mirrors, etc.). However, in other embodiments, the first optical relay 2000a and the second optical relay 2000b may incorporate one or more common components (e.g., lenses, mirrors, etc., or any combination thereof). For example, referring to FIG. 22, an optical relay system such as optical relay system 2200 may include a first optical relay 2200a and a second optical relay 2200b. In this case, the first optical relay 2200a incorporates a first lens 2202 and a second lens 2204, and the second optical relay 2200b incorporates a second lens 2204 and a third lens 2206. The optical relay system 2200 is incorporated into a beam path assembly that includes a wavefront compensation optical component (e.g., the wavefront compensation optical component 2100 described above) and one or both of the first optical component 2004a and the second optical component 2004b.

[0153] The first optical relay 2200a is positioned and configured to relay the image of the laser energy beam (e.g., propagating along the beam path 114) at the first object plane (i.e., at a plane within the first optical component 2004a) to a first image plane (i.e., a plane located at or within the wavefront compensation optic 2100) such that the image of the relayed laser energy beam at the first image plane is larger than the image at the first object plane. The second optical relay 2200b is positioned and configured to relay the image of the laser energy beam at the second object plane (i.e., at a plane at the wavefront compensation optic 2100, which may be the same as the first image plane), to a second image plane (i.e., a plane located at or within the second optical component 2004b) such that the image of the relayed laser energy beam at the second image plane is smaller than the image at the second object plane. In one embodiment, the first optical relay 2200a and the second optical relay 2200b are positioned and configured so that the size of the image of the relayed laser energy beam at the second image plane is the same as the size of the image of the laser energy beam at the first object plane. In other embodiments, the first optical relay 2200a and the second optical relay 2200b can be positioned and configured so that the size of the image of the relayed laser energy beam at the second image plane is larger or smaller than the size of the image of the laser energy beam at the first object plane.

[0154] 22 illustrates first optical relay 2200a and second optical relay 2200b each as including no optical components between their lenses, in other embodiments, one or more optical components (e.g., mirrors, etc.) may be interposed between the lenses of one or both of first optical relay 2200a and second optical relay 2200b. For example, referring to FIG. 23, optical relay system 2200 described above may be modified to incorporate multiple mirrors (e.g., mirrors 2302 and 2304) positioned along beam path 114 between second lens 2204 and third lens 2206 (thereby forming optical relay system 2300).

[0155] In general, one or both of the first optical component 2004a and the second optical component 2004b shown in any of Figures 20, 21, 22, 23, and 24 may be provided as one or more of the transmissive optical components described above, a laser gain medium, etc., or any combination thereof. In one embodiment, at least one of the first optical component 2004a and the second optical component 2004b is provided as an AO cell (e.g., made of crystalline Ge, GaAs, PbMoO, TeO, quartz, vitreous SiO, AsS, LiNbO, etc.) of any of the AOD systems described above. For example, the first optical component 2004a may be provided as the AO cell of the first AOD 402 described above. The second optical component 2004b may be provided as the AO cell of the second AOD 404 described above. Thus, the first optical component 2004a can be considered to be part of the first AOD 402, and the second optical component 2004b can be considered to be part of the second AOD 404. In one example, the AO cells of the first AOD 402 and the second AOD 404 can both be formed from the same material (e.g., Ge, GaAs, PbMoO4, TeO2, quartz, SiO2, As2S3, LiNbO3, etc., or any combination thereof). In such a case, although not shown, one or more additional optical components such as a phase retarder (e.g., for the purposes described above) may be provided in the beam path between the first optical component 2004a and the second optical component 2004b (e.g., in the beam path 114 shown in either FIG. 22 or FIG. 23, or in the beam path 114' shown in FIG. 24). For example, one or more phase retarders, such as those described above, may be positioned in the beam path at a position between the first optical component 2004a and the first lens 2202, or at a position between the second optical component 2004b and the third lens 2206, or at a position between the first lens 2202 and the third lens 2206, or at a similar position, or at any combination thereof.

[0156] If the first optical component 2004a and the second optical component 2004b are provided as AO cells of the first AOD 402 and the second AOD 404, respectively, as described above, the beam path 114 propagating from the first optical component 2004a shown in FIG. 23 may correspond to the first order beam 114' propagating from the first AOD 402 (e.g., as shown in FIG. 4). Similarly, a beam dump (not shown) may be provided to absorb the zeroth order beam (also not shown) propagating from the first optical component 2004a. In other embodiments, the zeroth order beam may be allowed to propagate from the first optical component 2004a to the second optical component 2004b (e.g., as shown in FIG. 24).

[0157] 24, the placement and configuration of the mirrors 2302 and 2304, as well as the placement and configuration of the lenses 2202, 2204, 2206, are such that the magnitude and direction of the angular difference between the first order beam path 114 and the zero order beam path 300 in the second optical component 2004b is the same (or at least substantially the same) as if all intervening optical components were removed and the second optical component 2004b were simply placed at the optical output of the first optical component 2004a. This can be useful in facilitating the capture and absorption (i.e., trapping) of laser energy propagating along undesired beam paths from the second optical component 2004b (e.g., using the beam dump system exemplarily described above).

[0158] 24, the zero-order beam path 300 does not follow the same sequence of optical components as the first-order beam path 114′. That is, the zero-order beam path 300 does not propagate through the optical relay system 2300 or be reflected by the wavefront compensation optics 2100, whereas the first-order beam path 114′ propagates through the optical relay system 2300 and is reflected by the wavefront compensation optics 2100. As a result, the thermal lensing effect (which may include focusing effects, among other distortions, as described above) accumulated by the first-order beam in the first optical component 2004a is compensated for by the time the first-order beam reaches the second optical component 2004b, but the thermal lensing effect (which may also include focusing effects) accumulated by the zero-order beam in the first optical component 2004a is not compensated for by the time the zero-order beam reaches the second optical component 2004b. As a result, the zero-order beam propagating from the first optical component 2004a is much smaller than the first-order beam by the time the two beams reach the second optical component 2004b. To compensate for this difference, the optical relay system 2300 may be modified (or configured) to include a lens 2402 (e.g., a single diverging lens) positioned in the zero-order beam path 300 propagating from the first optical component 2004a to adjust the size of the zero-order beam that ultimately propagates to the second optical component 2004b. In one embodiment, the position and / or orientation of the lens 2402 may be adjustable to shift the location at which the zero-order beam enters the second optical component 2004b.

[0159] 24, the zero-order beam path 300 does not follow the same sequence of optical components as the first-order beam path 114', it will be appreciated that in other embodiments the zero-order beam path 300 may follow the same sequence of optical components as the first-order beam path 114'. For example, (e.g., the zero-order beam path 300 passes through the second lens 2204 to compensationOne or more optical elements (e.g., one or more mirrors) may be provided to transmit the zero-order beam path 300 exiting the first optical component 2004a (towards optical element 2100, towards mirror 2302, towards mirror 2304, through third lens 2206, and towards second optical component 2004b) to the first lens 2202 along a direction at least generally parallel to the first order beam path 114'. In this case, lens 2402 may be omitted from the beam path assembly. In another example, the first lens 2202, the second lens 2204, the wavefront compensation The size and location of at least one of optical component 2100, mirror 2302, mirror 2304, and third lens 2206 may be adjusted to be located in both zero-order beam path 300 and first-order beam path 114'.

[0160] E. Optical Component Mounting Embodiments Any of the optical components described above, such as lenses, windows, phase retarders, filters, mirrors, etc., can be held in place within the beam path assembly using optical mounts. Optical mounts are typically coupled to the frame or wall of the apparatus 100, to an optical breadboard integrated within the apparatus 100, or the like. Often, mounts are configured to exert one or more compressive forces on the optical components to hold and maintain their position over a range of environmental conditions. However, the optical surfaces of some optical components can be so sensitive to mechanical stress that even relatively small compressive forces can deform the optical surfaces in undesirable ways. As used herein, "optical surface" can refer to a reflective surface (e.g., if the optical component is a mirror) or a refractive surface (e.g., if the optical component is a lens, etc.).

[0161] One particular type of optical component having optical surfaces that are particularly susceptible to undesirable deformation is a membrane-type deformable mirror. Accordingly, in one embodiment illustratively shown in FIG. 25 , a mount 2500 for holding a membrane-type deformable mirror can include a base, such as base 1700 shown and described with respect to FIG. 17 , and a mount plate 2502 coupled to base 1700. Mount plate 2502 is coupled to base 1700 at a connector 2504 of base 1700. In one embodiment, connector 2504 is threaded, and mount plate 2502 includes an internally threaded bore configured to engage threaded connector 2504. In other embodiments, connector 2504 is secured within the bore of mount plate 2502 by other attachment means (e.g., adhesive, welding, one or more clamps, one or more screws, etc.). Mount plate 2502 may be coupled to any suitable or known fixed or adjustable optical mount assembly (not shown) by any method known in the art (e.g., via one or more screws, clamps, springs, adhesives, etc.). In embodiments in which coupling portion 2504 is threaded into a threaded bore in mount plate 2502, mount 2500 may also include a locking nut 2506. Locking nut 2506 may be threaded into the threaded bore in mount plate 2502 to help lock coupling portion 2504 within the threaded bore in mount plate 2502.

[0162] In the illustrated embodiment, the membrane-type deformable mirror 1600 is coupled to the base 1700 such that stress (or significant stress) is not induced in the membrane region 1608 of the mirror 1600. Additionally, the perforations 1704 are shown extending from the surface 1702 the entire length of the coupling portion 2504, allowing fluid (e.g., air) to pass through the perforations 1704 to pressurize or depressurize the pocket 1606 in the manner described above. A fitting 2508 may be inserted into one end of the perforations 1704 to facilitate transferring fluid through the perforations 1704. The fitting 2508 may be configured to couple to a hose (e.g., to a first end of a hose such as the pneumatic hose, hydraulic hose, etc. described above) in any suitable or known manner.

[0163] While Figure 25 shows mount 2500 as being coupled to base 1700 shown in Figure 17 (for securing mirror 1600), it will be understood that mount 2500 may be coupled to other bases for securing mirror 1600 or other membrane-based deformable mirrors. For example, mount 2500 may be coupled to base 1700 shown in Figure 18 (for securing mirror 1800) or to base 1700 shown in Figure 19 (for securing mirror 1900). Also, while mount 2500 is described above as including a base for use in securing a membrane-based deformable mirror, it will be understood that mount 2500 may include any other suitable base for use in securing other optical components.

[0164] F. Embodiments Generally Relating to Chromatic Dispersion Compensation It should be understood that the AOD is a spectrally dispersive element, such that the angle at which the laser energy beam is deflected by the AOD depends on the wavelength of the laser energy beam. If the spectral linewidth of the laser energy beam incident on the AOD is too large, diffraction of the incident beam within the AOD will result in a deflected laser energy beam that can be spatially distorted in an undesirable manner (e.g., resulting in an undesirable distortion such as an elongated process spot on the workpiece 102) or spatially resolved into many beamlets having different wavelengths or spectral linewidths. Therefore, for laser processing applications such as those described above, it is preferable that the laser energy beam ultimately incident on the AOD in the first positioner 106 have a suitably narrow spectral linewidth to minimize or eliminate the above-mentioned adverse effects of AOD diffraction events on a wide linewidth laser energy beam. The spectral linewidth can be measured, for example, based on the full width at half maximum (FWHM) of the optical power spectral intensity within the laser energy beam.

[0165] Many conventional laser sources 104 capable of producing laser output in the ultraviolet, visible, or NIR regions of the electromagnetic spectrum produce laser energy beams with spectral linewidths that are suitably narrow for laser processing applications. Laser sources 104, such as high-power CW gas lasers (e.g., carbon dioxide or carbon monoxide CW lasers having average powers greater than about 300 W) and other low-power CW or pulsed gas lasers (e.g., having average powers less than about 300 W), can, in some cases, produce laser pulses with spectral linewidths in the SWIR, MWIR, or LWIR regions that are suitably narrow for laser processing applications. In these cases, the narrow spectral linewidths output by such gas lasers are achieved by incorporating one or more spectrally selectable devices (e.g., etalons or gratings) into the laser resonator of the laser source 104.

[0166] However, in certain embodiments, the spectral linewidth of the laser energy beam ultimately incident on the AOD is not suitably narrow for laser processing applications. For example, laser energy beams generated by gas lasers (e.g., high- or low-power CW or pulsed carbon dioxide or carbon monoxide gas lasers) lacking an appropriate spectrally selectable device may produce laser energy beams with undesirably broad spectral linewidths. If an AOD (e.g., incorporating an AO cell formed from crystalline germanium) is used to deflect such beams, the AOD may produce a deflected laser energy beam that may be spatially distorted or spatially resolved in undesirable ways, as described above. In such embodiments, the beam path assembly may include one or more chromatic dispersion compensators (each also referred to herein simply as a “dispersion compensator”) disposed in the beam path 114. Typically, dispersion compensators may be provided as prisms, gratings, or the like, or any combination thereof. It will be appreciated that the configuration of the dispersion compensator will vary depending on one or more factors, such as the wavelength of the laser energy beam propagating along beam path 114, the beam size of the laser energy beam, etc. For example, if the laser energy beam propagating along beam path 114 has a wavelength in the infrared region of the electromagnetic spectrum (e.g., in the MWIR or LWIR regions spanning wavelengths such as those ranging from 3 μm (or thereabouts) to 15 μm (or thereabouts)), the dispersion compensator may be provided as a dispersive prism formed from materials such as fused lime, silicon, calcium fluoride, magnesium fluoride, germanium, zinc selenide, zinc sulfide, potassium bromide, sapphire, sodium chloride, etc.

[0167] i. Example of Dispersion Compensator 26, in one embodiment, a dispersion compensator 2600 is positioned on the beam path 114 at a position optically upstream of the AOD 2602. Generally, the dispersion compensator 2600 should be oriented to disperse the laser energy beam in a plane parallel (or at least generally or substantially parallel) to the deflection plane of the AOD 2602. In the embodiment shown in FIG. 26, the AOD 2602 is an AOD of the first positioner 106 (e.g., the first AOD 402 or the second AOD 404).

[0168] 27, the dispersion compensator 2600 is disposed between components of the optical relay system on the beam path 114 at a position optically upstream of the AOD 2602. For example, the optical relay system may include a first beam expander 2700 disposed at a position optically upstream of the dispersion compensator 2600 and a second beam expander 2702 disposed at a position optically downstream of the dispersion compensator 2600. The first beam expander 2700 is positioned and configured to expand the laser energy beam propagating along the beam path 114 (e.g., from a first beam size to a second beam size larger than the first beam size), and the second beam expander 2702 is positioned and configured to reduce (or “de-reduc”) the laser energy beam propagating along the beam path 114 from the dispersion compensator 2600 (e.g., from at or around the second beam size to the first beam size or to a third beam size). The third beam size may be smaller than the second beam size, and may be smaller or larger than the first beam size. Similar to the embodiment shown in Figure 26, the AOD 2602 shown in Figure 27 is an AOD (e.g., first AOD 402 or second AOD 404) of the first positioner 106. If the beam size expansion provided by the first beam expander 2700 is sufficiently large, the design specifications of the dispersion compensator 2600 can be advantageously relaxed (which generally reduces the cost of manufacturing the dispersion compensator 2600).

[0169] In some cases, the primary laser energy beam diverges as it propagates along the beam path 114′. Thus, the beam size of the primary laser energy beam at a first position along the primary beam path 114′ (e.g., at the optical input of the second positioner 108) may be larger than the beam size of the laser energy beam at the surface of the AOD 2602 (e.g., if the AOD 2602 is the first AOD 402 described above). In such cases, referring to FIG. 28 , a dispersion compensator 2600 can be positioned on the beam path 114 at a position optically downstream of the AOD 2602. In the embodiment shown in FIG. 28 , the AOD 2602 is the second AOD 404 of the first positioner 106. Accordingly, beam path 114 corresponds to primary beam path 114". As such, the illustrated distance "d" (also referred to herein as "path length") represents the length along beam path 114 (e.g., primary beam path 114") between the optical output of second AOD 404 and the optical input of second beam positioner 108 (e.g., second positioner 108a or second positioner 108b). Typically, distance "d" may be in the range of 1 m (or thereabouts) to 5 m (or thereabouts). However, it will be appreciated that distance "d" may be shorter, for example, if one or more defocusing elements (e.g., one or more suitable lenses, mirrors, etc.) are inserted into beam path 114.

[0170] In the embodiments shown in Figures 26 to 28, the dispersion compensator 2600 is provided as a dispersing prism (e.g., an equilateral dispersing prism), although it will be appreciated that other suitable prism geometries (e.g., an equilateral triangular prism) or other types of dispersion compensators, such as a grating, may be used.

[0171] In embodiments in which the apparatus 100 includes multiple second positioners 108 (e.g., second positioners 108a and 108b as described above with respect to FIG. 1), the beam path assembly of the apparatus 100 may include a corresponding number of dispersion compensators 2600. For example, with reference to FIG. 29, the beam path assembly may include a first dispersion compensator 2600a and a second dispersion compensator 2600b. The first dispersion compensator 2600a is disposed on the beam path 114 deflected within the first primary angular range 116a, and the second dispersion compensator 2600b is disposed on the beam path 114 deflected within the second primary angular range 116b. In embodiments in which the beam path 114 is a beam path deflected by the first positioner 106 (as described above with respect to FIG. 4), the beam path 114 corresponds to the primary beam path 114″ described above.

[0172] 29, the first dispersion compensator 2600a and the second dispersion compensator 2600b are each mounted to the optical wall 2902 (e.g., on a first side 2904 thereof). Similarly, the second positioners 108a and 108b may, but need not, be mounted to the first side 2904 of the optical wall 2902. The beam path 114 deflected by the first positioner 106 may be deflected within a first primary angular range 116a or a second primary angular range 116b. When beam path 114 is deflected within a first primary angular range, it is relayed through an optical port formed in optical wall 2902 (i.e., first optical port 2906a) and then directed to first dispersion compensator 2600a (e.g., reflected by a set of first mirrors such as mirrors 2908a1, 2908a2, and 2908a3 (each collectively referred to as “first mirror 2908a”)). Similarly, when beam path 114 is deflected within a second primary angular range 116b, it is relayed through an optical port formed in optical wall 2902 (i.e., second optical port 2906b) and then directed to second dispersion compensator 2600b (e.g., reflected by a set of second mirrors such as mirrors 2908b1, 2908b2, and 2908b3 (each collectively referred to as “second mirror 2908b”)). Beam path 114 exiting first dispersion compensator 2600a is directed to second positioner 108a (e.g., reflected by mirror 2910a). Similarly, beam path 114 exiting second dispersion compensator 2600b is directed to second positioner 108b (e.g., reflected by mirror 2910b).

[0173] In the embodiment shown in FIG. 29, each of mirrors 2908a, 2908b, 2910a, and 2910b is mounted to first side 2904 of optical wall 2902. However, it will be understood that such optical components may be provided on beam path 114 using other suitable techniques. Furthermore, it will be understood that the beam path assembly shown in FIG. 29 may be provided in different configurations (e.g., with different locations for mirrors 2908a, 2908b, 2910a, and 2910b, different locations for second positioner 108, more or fewer mirrors than shown, or the like, or any combination thereof). In one embodiment, the orientation of the first dispersion compensator 2600a (e.g., relative to the first mirror 2908a3) is different from the orientation of the second dispersion compensator 2600a (e.g., relative to the first mirror 2908b3), accounting for the difference in dispersion introduced into the primary laser energy beam when the first positioner 106 is operated to deflect the beam path 114 within the first primary angular range 116a versus when the first positioner 106 is operated to deflect the beam path 114 within the second primary angular range 116b.

[0174] G. Additional Beam Path Assembly Embodiments 29 , the apparatus 100 may include one or more mirrors disposed on a second side of the optical board 2902 (opposite the first side 2904) between the optical output of the first positioner 106 and the first optical port 2906 a for directing the beam path 114 deflected within the first primary angular range 116 a to the first optical port 2906 a. Similarly, the apparatus 100 may include one or more mirrors disposed on the second side of the optical board 2902 between the optical output of the first positioner 106 and the second optical port 2906 b for directing the beam path 114 deflected within the second primary angular range 116 b to the second optical port 2906 b. An exemplary embodiment of a beam path assembly on the second side of the optical board 2902 will be described with reference to FIG. 30 .

[0175] Referring to Figure 30, a second side of the optical board 2902 is identified at 3000. Also shown are a first optical port 2906a, a second optical port 2906b, a first optical component 2004a, a second optical component 2004b, and the laser source 104 described above. In the embodiment shown in Figure 30, the first optical component 2004a is provided as the AO cell of the first AOD 402 (e.g., as described above), and the second optical component 2004b is provided as the AO cell of the second AOD 404 (e.g., as described above). Thus, the first optical component 2004a can be considered to be part of the first AOD 402, and the second optical component 2004b can be considered to be part of the second AOD 404.

[0176] As exemplarily shown in FIG. 30, multiple mirrors may be provided to facilitate directing the beam path 114 from the laser source 104 to the first optical port 2906a and the second optical port 2906b. For example, a first set of mirrors 3004a and 3004b may be provided to direct the beam path 114 from the laser source 104 to the first optical component 2004a, a second set of mirrors 3006a and 3006b may be provided to direct the beam path 114 from the first optical component 2004a to the second optical component 2004b, a third set of mirrors 3008a, 3010a, 3012a may be provided to direct the beam path 114 from the second optical component 2004a to the first optical port 2906a (if deflected within the first primary angular range 116a), and a fourth set of mirrors 3008b, 3010b, 3012b may be provided to direct the beam path 114 from the second optical component 2004a to the second optical port 2906b (if deflected within the second primary angular range 116b). In the beam path assembly shown in FIG. 30, mirror 3008a may be provided as a pick-off mirror.

[0177] Optical components such as first optical component 2004a, second optical component 2004b, and mirrors 3004a, 3004b, 3006a, 3006b, 3008a, 3008b, 3010a, 3010b, 3012a, and 3012b may be attached to second side 3000 of optical board 2902 by any suitable technique described herein or known in the art. However, it will be understood that other suitable techniques may be used to provide such optical components on beam path 114. Furthermore, it will be appreciated that the beam path assembly shown in FIG. 30 may be provided in different configurations (e.g., different arrangements of mirrors 3004a, 3004b, 3006a, 3006b, 3008a, 3008b, 3010a, 3010b, 3012a, 3012b, different arrangements of optical components 2004a and 2004b, more or fewer mirrors than shown, or the like, or any combination thereof). For example, first optical component 2004a may be positioned on beam path 114 at a position between mirror 3006b and second optical component 2004b. In another example, second optical component 2004b may be positioned on beam path 114 at a position between first optical component 2004a and mirror 3006a.

[0178] i. Discussion of the First and Second Optical Components In one embodiment, the first optical component 2004a is oriented relative to the second optical component 2004b in the beam path assembly shown in Figure 30 so that the second axis of rotation associated with the second AOD 404 incorporating the second optical component 2004b is parallel (or at least substantially parallel) to the first axis of rotation associated with the first AOD 402 incorporating the first optical component 2004a. In this case, the mirrors 3006a and 3006b are oriented to ensure that the plane of deflection of the first AOD 402, when projected onto the second AOD 404, is different from (e.g., perpendicular to or oblique to) the plane of deflection of the second AOD 404. See, for example, International Publication WO 2019 / 060590 A1 for how the plane of deflection may be rotated.

[0179] In another embodiment, the first optical component 2004a is oriented relative to the second optical component 2004b in the beam path assembly shown in Figure 30 so that the second axis of rotation associated with the second AOD 404 incorporating the second optical component 2004b is orthogonal (or at least substantially orthogonal or oblique to) the first axis of rotation associated with the first AOD 402 incorporating the first optical component 2004a. In this case, the mirrors 3006a and 3006b are oriented to ensure that the deflection plane of the first AOD 402, when projected onto the second AOD 404, remains orthogonal to (or at least substantially orthogonal to) the deflection plane of the second AOD 404. See, for example, International Publication WO 2019 / 060590 A1 for how rotation of the deflection plane may be prevented.

[0180] ii. Discussion of additional optical components Although not shown, the beam path assembly shown in FIG. 30 may include one or more other optical components (e.g., beam traps, beam dump systems, beam expanders, shapers, beam splitters, apertures, filters, collimators, lenses, mirrors, prisms, polarizers, phase retarders, DOEs, ROEs, etc., or any combination thereof) to focus, expand, collimate, shape, polarize, filter, split, combine, crop, absorb, or otherwise modify, condition, direct, etc., the laser energy beam as it propagates along beam path 114 (e.g., from laser source 104 to one or both of optical ports 2906a and 2906b). Additional optical components that may be incorporated into the beam path assembly shown in FIG. 30 are briefly described below. It will be understood that a beam path assembly may include one or more or all of these optical components in any combination.

[0181] In one embodiment, an optical component such as a beam expander, collimator, etc., or any combination thereof, may be positioned on the beam path 114 at a position between the mirror 3004b and the first optical component 2004a.

[0182] In other embodiments, one or more beam trap or beam dump systems may be provided to trap or absorb laser energy propagating along undesired beam paths from the first optical component 2004 a, or from the second optical component 2004 b, or a combination thereof. For example, a first beam trap or beam dump system may be positioned between mirror 3006 b and the second optical component 2004 b to selectively trap laser energy propagating from the first optical component 2004 a along all beam paths other than the first order beam path 114′ (and optionally the zero order beam path 300 (not shown)). Similarly, a second beam trap or beam dump system may be positioned between second optical component 2004b and mirror 3008a to trap laser energy propagating from second optical component 2004b along beam paths other than primary beam path 114″. In one embodiment, the first beam dump system is provided as integrated beam dump system 700 and the second beam dump system is provided as integrated beam dump system 1000.

[0183] In other embodiments, wavefront compensation optics such as wavefront compensation optics 2002 or 2100, or any combination thereof, may be provided to compensate for actual or predicted wavefront distortions (e.g., as described above) (e.g., located at a position on beam path 114 between first optical component 2004a and second optical component 2004b, i.e., at a position on beam path 114').

[0184] In other embodiments, one or more optical components comprising an optical relay system, such as optical relay systems 2000, 2200, 2300, or 2400 described above with respect to any of Figures 20, 21, 22, 23, or 24, may include wavefront compensation optics to facilitate compensation for wavefront distortions (e.g., as described above).

[0185] 30, one or more phase retarders (e.g., as described above) may be disposed on the beam path 114 to rotate the plane of polarization of the laser energy beam incident on the second optical component 2004b (e.g., depending on the wavelength of the laser energy beam and the material forming the second optical component 2004b, as described above) to ensure that the plane of polarization of the laser energy beam is parallel or perpendicular (or at least substantially parallel or perpendicular) to the diffraction axis of the second optical component 2004b. If desired, one or more phase retarders may also be disposed on the beam path 114 (e.g., depending on the wavelength of the laser energy beam and the material forming the first optical component 2004a, as described above) to rotate the plane of polarization of the laser energy beam incident on the first optical component 2004a to ensure that the plane of polarization of the laser energy beam is parallel or perpendicular (or at least substantially parallel or perpendicular) to the diffraction axis of the first optical component 2004a. In one example embodiment, first optical component 2004a and second optical component 2004b are formed from an AO cell material such as crystalline germanium, and the laser energy beam incident on first optical component 2004a and second optical component 2004b is characterized as having a wavelength in the range of 9 μm (or thereabouts) to 11 μm (or thereabouts) and an average power in the range of 20 W (or thereabouts) to 20 kW (or thereabouts). In such an example embodiment, one of mirrors 3006a and 3006b may be provided as a reflective phase retarder (e.g., configured to provide a 180 degree phase shift). Alternatively, both mirrors 3006a and 3006b may be provided as reflective phase retarders (e.g., configured to provide a 90 degree phase shift).However, it will be understood that the first optical component 2004a and the second optical component 2004b may be formed from other suitable AO cell materials, and the laser energy beam incident on the first optical component 2004a and the second optical component 2004b may be characterized as having other suitable wavelengths (e.g., in the UV or visible regions of the electromagnetic spectrum) and power characteristics (e.g., average power, peak power, etc.) sufficient to process the workpiece (e.g., as described above).

[0186] iii. Laser Sensor System Embodiments Optionally, apparatus 100 further includes one or more laser sensor systems, such as laser sensor systems 3014a and 3014b. In this embodiment, mirrors 3010a and 3010b are provided as partially transmitting mirrors configured to reflect a majority of the light in an incident laser energy beam and transmit a small amount of light (e.g., 2% or thereabouts), and the laser sensor systems are positioned to receive the light transmitted through the corresponding partially transmitting mirror. For example, laser sensor system 3014a is positioned to receive the light transmitted through mirror 3010a, and laser sensor system 3014b is positioned to receive the light transmitted through mirror 3010b.

[0187] Generally, each of laser sensor systems 3014a and 3014b includes a photodetector configured to detect or measure laser energy or power transmitted therethrough and generate sensor data based on the detection or measurement. The sensor data is output by suitable means to controller 122, where it may then be processed to support various functions of apparatus 100, such as real-time pulse energy control (e.g., to compensate for changes in laser power), system calibration (e.g., to compensate for transmission changes in the AOD system of first positioner 106, for RF power, frequency, etc.), or any combination thereof.

[0188] Because the laser sensor systems 3014a and 3014b are located optically downstream of the first optical component 2004a and the second optical component 2004b, respectively, which are the AODs of the first positioner 106, the photodetector readings may vary depending on the position and angle of the energy beam incident on the photodetectors. As such, movement of the incident laser energy beam on the photodetectors may result in reading errors, which may lead to erroneous power control, system calibration, etc. To reduce or eliminate spatial and directional sensitivity associated with the photodetectors, each of the laser sensor systems may include a beam expander and / or diffuser positioned to expand and / or diverge the laser energy beam before it strikes the photodetector.

[0189] In other embodiments, each of the laser sensor systems 3014a and 3014b may include an integrating sphere 3016 positioned optically upstream of the photodetector to reduce spatial and directional sensitivity associated with the photodetector. The integrating sphere 3016 may be provided as an alternative to or a complement to the use of the beam expander / diffuser described above. As generally known in the art, the integrating sphere 3016 is an optical component that includes a hollow spherical (or at least substantially spherical) cavity, the inner surface of which is coated with a diffusely reflective coating. The integrating sphere 3016 includes an illumination port (shown but not labeled) and a detection port. The integrating sphere 3016 is positioned such that light propagating from the partially transmitting mirror (i.e., from mirror 3010a or 3010b) can pass through the illumination port and into the corresponding cavity of the integrating sphere 3016. Light incident on any point on the interior surface of the cavity is scattered and ultimately exits the integrating sphere 3016 at the detection port and is incident on a photodetector (identified as 3018 in this embodiment).

[0190] H. AOD Driving Method Embodiments i. Beam Splitting Embodiments As noted above, Figure 4 generally illustrates deflection of the beam path 114 incident on the multi-axis AOD system 400 within a primary angular range 116. To achieve the deflection scheme described above with respect to Figure 3, the AOD 402 may be operated or driven by a first applied RF drive signal having a drive frequency within one of a plurality of first frequency ranges, and the second AOD 404 may be operated or driven by a second applied RF drive signal having a drive frequency within a corresponding one of a plurality of second frequency ranges. For example, with reference to Figures 1, 4, and 31, the first RF drive signal applied to the first AOD 402 may have a first drive frequency f1 within the first frequency range 3102a to deflect the beam path 114 incident on the multi-axis AOD system 400 within the first primary angular range 116a (to the second positioner 108a). The second RF drive signal applied to the second AOD 404 may have a second drive frequency f2 within a corresponding second frequency range 3104a. To deflect the beam path 114 entering the multi-axis AOD system 400 within a second primary angular range 116b (to the second positioner 108b), the first RF drive signal applied to the first AOD 402 may have a first drive frequency f1 within the first frequency range 3102b. The second RF drive signal applied to the second AOD 404 may have a second drive frequency f2 within a corresponding second frequency range 3104b.

[0191] In general, the first frequency range 3102a does not overlap with and is not adjacent to the first frequency range 3102b. Similarly, the second frequency range 3104a does not overlap with and is not adjacent to the second frequency range 3104b. Thus, there are “gaps” between the first frequency range 3102a and the first frequency range 3102b and between the second frequency range 3104a and the second frequency range 3104b. In general, the gap between the first frequency range 3102a and the first frequency range 3102b (i.e., the “first frequency range gap”) may be larger, smaller, or equal to the gap between the second frequency range 3104a and the second frequency range 3104b (i.e., the “second frequency range gap”). Either the first frequency range gap or the second frequency range gap may have a width of 0.3 MHz, 0.5 MHz, 0.7 MHz, 0.9 MHz, 1 MHz, 2 MHz, 5 MHz, 10 MHz, etc., or any value between these values.

[0192] Generally, the first frequency range 3102a, the first frequency range 3102b, the second frequency range 3104a, and the second frequency range 3104b span a range of frequencies. For example, any of the first frequency range 3102a, the first frequency range 3102b, the second frequency range 3104a, and the second frequency range 3104b may be equal to 3 MHz, 5 MHz, 7 MHz, 9 MHz, 10 MHz, 12 MHz, 15 MHz, 20 MHz, etc., or a value between these values. The first frequency range 3102a may be greater than, less than, or equal to the first frequency range 3102b. Similarly, the second frequency range 3104a may be greater than, less than, or equal to the second frequency range 3104b. The first frequency range 3102a may be greater than, less than, or equal to the second frequency range 3104a. Similarly, the first frequency range 3102b may be greater than, less than, or equal to the second frequency range 3104b.

[0193] 31 , in response to a first applied RF drive signal having a first drive frequency f within a first frequency range 3102a, the first AOD 402 deflects the beam path 114 by an angle within a first AOD angular range 406a by rotating the incident laser energy beam about a first axis of rotation. Similarly, in response to a first applied RF drive signal having a first drive frequency f within a first frequency range 3102b, the first AOD 402 deflects the beam path 114 by another angle within a first AOD angular range 406b by rotating the incident laser energy beam about the first axis of rotation. As will be appreciated, each of the first AOD angular ranges 406a and 406b represents a specific embodiment of the “first AOD angular range 406” described above, and thus may be collectively referred to as the “first AOD angular range 406.”

[0194] Similarly, in response to a second applied RF drive signal having a second drive frequency f2 within the second frequency range 3104a, the second AOD 404 rotates the incident laser energy beam about the second axis of rotation, thereby deflecting the beam path 114' by another angle within the second AOD angular range 408a. Similarly, in response to a second applied RF drive signal having a second drive frequency f2 within the second frequency range 3104b, the second AOD 404 rotates the incident laser energy beam about the second axis of rotation, thereby deflecting the beam path 114' by another angle within the second AOD angular range 408b. It will be appreciated that each of the second AOD angular ranges 408a and 408b represents a specific embodiment of the "second AOD angular range 408" described above, and thus may be collectively referred to as the "second AOD angular range 408."

[0195] As described above, by driving the first AOD 402 (by applying a first drive frequency to the first AOD 402 that is within either the first frequency range 3102a or the first frequency range 3102b) and driving the second AOD 404 (by applying a second drive frequency to the second AOD 404 that is within either the second frequency range 3104a or the second frequency range 3104b), the resulting scan area of ​​the multi-axis AOD system 400 is effectively divided into multiple sub-scan areas (i.e., the first sub-scan area 3106a and the second sub-scan area 3106b).

[0196] a. Additional discussion on bias and dispersion As described above, the AOD is a spectrally dispersive element that can distort (e.g., elongate) the process spot that ultimately impinges on the workpiece 102. The degree to which the process spot is distorted is proportional to the spectral linewidth of the laser energy beam and can be characterized, at least in part, as proportional to the deflection caused by the AOD (or by the sum of the deflections caused by multiple AODs). For example, the spectral dispersion caused by the sum of the deflections of the first AOD 402 and the second AOD 404 can be expressed as: Relative to TIFF0007819261000004.tif8170.

[0197] Although a dispersion compensator 2600, such as a prism, can compensate for spectral dispersion as described above, a given prism in combination with a given beam size can only compensate for a fixed amount of spectral dispersion. Thus, the act of driving the AOD to deflect the laser energy beam may still impart some distortion to the process spot on the workpiece 102. The amount of distortion imparted to the process spot on the workpiece 102 can be kept sufficiently low (e.g., so as not to adversely affect processing of the workpiece 102) by orienting the first dispersion compensator 2600a (e.g., relative to the first mirror 2908a3) to optimally compensate for spectral dispersion resulting from deflection at or near the center of the first sub-scan region 3106a, and orienting the second dispersion compensator 2600b (e.g., relative to the first mirror 2908b3) to optimally compensate for spectral dispersion resulting from deflection at or near the center of the second sub-scan region 3106b, while balancing the sizes of the first sub-scan region 3106a and the second sub-scan region 3106b with the spectral linewidth of the laser energy beam.

[0198] In one embodiment, the drive frequencies (i.e., f1 and f2) that define the centers of the first and second sub-scan regions 3106a and 3106b are: TIFF0007819261000005.tif8170 is the second sub-scan area 3106b TIFF0007819261000006.tif8170. f1 for the first sub-scan area 3106a may be selected to be equal to (or at least substantially equal to) f2 for the second sub-scan area 3106b. Similarly, f2 for the first sub-scan area 3106a may be selected to be equal to (or at least substantially equal to) f1 for the second sub-scan area 3106b. TIFF0007819261000007.tif8170 is the second sub-scan area 3106b TIFF0007819261000008.tif8170, the magnitude of the spectral dispersion imparted to the laser energy beam deflected within the first sub-scan region 3106a is equal to (or at least substantially equal to) the magnitude of the spectral dispersion imparted to the laser energy beam deflected within the second sub-scan region 3106b, but the directions of the spectral dispersion are different. Thus, the first dispersion compensator 2600a may have the same configuration as the second dispersion compensator 2600b, but the orientation of the first dispersion compensator 2600a (e.g., relative to the first mirror 2908a3) is different from the orientation of the second dispersion compensator 2600b (e.g., relative to the first mirror 2908b3). That is, the orientation of the first dispersion compensator 2600a (e.g., relative to the first mirror 2908a3) may correspond to the direction of spectral dispersion imparted to a laser energy beam deflected at or near the center of the first sub-scan region 3106a. The orientation of the second dispersion compensator 2600b (e.g., relative to the first mirror 2908b3) may correspond to the direction of spectral dispersion imparted to a laser energy beam deflected at or near the center of the second sub-scan region 3106b.

[0199] b. Additional discussion on subscan areas In the embodiment shown in Figure 31, first frequency ranges 3102a and 3102b are selected in coordination with second frequency ranges 3104a and 3104b to generate a pair of square-shaped sub-scan areas 3106a and 3106b that are spatially offset from one another in a first direction (e.g., by an angle corresponding to the first frequency range gap) and in a second direction (e.g., by an angle corresponding to the second frequency range gap). When the first frequency range gap is equal to the second frequency range gap, the closest point between sub-scan areas 3106a and 3106b (i.e., the lower right corner of first sub-scan area 3106a and the upper left corner of second sub-scan area 3106b, as shown in Figure 31) is 41% larger than either the first frequency range gap or the second frequency range gap. Also, the closest point between sub-scan areas 3106a and 3106b is actually a point, not a line. Thus, if beam distortion occurs due to beam clipping on a pickoff mirror (e.g., mirror 3008a) used to selectively reflect a laser energy beam deflected within the first sub-scan region 3106a (i.e., within the first primary angular range 116a) relative to a laser energy beam deflected within the second sub-scan region 3106b (i.e., within the second primary angular range 116b), such distortion will occur much less frequently than if the beam distortion occurs only at one corner of the sub-scan region, rather than along the entire edge of the sub-scan region. However, it will be appreciated that the size of one or both of the first and second frequency range gaps can be increased or decreased independently or in concert, as needed, depending on the sensitivity (or insensitivity) of the workpiece processing to such distortions.

[0200] Although the above has been described with respect to an arrangement of sub-scan areas consisting of a pair of equally sized square sub-scan areas 3106a and 3106b spatially offset from one another in a first direction (e.g., by an angle corresponding to a first frequency range gap) and in a second direction (e.g., by an angle corresponding to a second frequency range gap), as shown in Figure 31, it will be appreciated that other embodiments are also contemplated.

[0201] For example, the arrangement of sub-scan areas 3106a and 3106b may be different from that shown in Figure 31 (e.g., as shown in Figure 32). In other examples, the frequency range at which the AOD is driven may be selected to generate more than two square-shaped sub-scan areas, or to generate one or more sub-scan areas having shapes other than square (e.g., rectangular, circular, oval, triangular, hexagonal, etc.), or to generate sub-scan areas of different sizes, or the like, or any combination thereof.

[0202] 33, the first AOD 402 may be driven by a first applied RF drive signal having a drive frequency within the first frequency range 3300, and the second AOD 404 may be driven by a second applied RF drive signal having a drive frequency within a corresponding one of the plurality of second frequency ranges 3104a and 3104b described above. Thus, to deflect the beam path 114 entering the multi-axis AOD system 400 within the first primary angular range 116a (to the second positioner 108a), the first RF drive signal applied to the first AOD 402 may have a first drive frequency f1 within the first frequency range 3300, and the second RF drive signal applied to the second AOD 404 may have a second drive frequency f2 within the second frequency range 3104a. In order to deflect the beam path 114 entering the multi-axis AOD system 400 within the second primary angular range 116b (to the second positioner 108b), the first RF drive signal applied to the first AOD 402 may have a first drive frequency f1 within the first frequency range 3300, and the second RF drive signal applied to the second AOD 404 may have a second drive frequency f2 within the second frequency range 3104b. By driving the first AOD 402 (by applying a first drive frequency within the first frequency range 3300 to the first AOD 402) and driving the second AOD 404 (by applying a second drive frequency within the second frequency range 3104a or the second frequency range 3104b to the second AOD 404), the resulting scan area of ​​the multi-axis AOD system 400 is effectively divided into multiple sub-scan areas (i.e., first sub-scan area 3302a and second sub-scan area 3302b). It will also be appreciated that the AODs of the multi-axis AOD system 400 can be similarly driven by applying drive frequencies within the ranges illustratively shown in Figure 34.

[0203] Driving the AODs of the multi-axis AOD system 400 with the drive frequency ranges shown in Figure 33 or 34 can be useful, for example, in correcting or at least partially compensating for noticed telecentricity errors when the second positioner 108 includes a galvanometer mirror system. In such applications, frequencies within one or more sub-ranges of the first frequency range 3300 (e.g., within the first sub-range 3304a, the second sub-range 3304b, etc., or any combination thereof) may be applied to the first AOD 402 (e.g., as shown in Figure 33) to correct for telecentricity errors present along one axis (e.g., the X-axis), or to the second AOD 404 (e.g., as shown in Figure 34) to correct for telecentricity errors present along another axis (e.g., the Y-axis).

[0204] ii. Pulse Slicing Embodiments As described above, the first positioner 106 can be operated to perform pulse slicing, i.e., to temporally divide a common laser pulse (also referred to herein as a “mother laser pulse”) into at least two laser pulses. The temporally divided portions of the common mother laser pulse are also referred to herein as “pulse slices.” One embodiment of pulse slicing is exemplarily shown in FIG. 35 , in which a mother laser pulse 3500 is temporally divided into two pulse slices. Specifically, during a first slice period p1, the mother laser pulse 3500 is divided into a first pulse slice 3500a, and during a second slice period p2, the mother laser pulse 3500 is divided into a second pulse slice 3500b. As will be appreciated, the pulse duration of a pulse slice generally corresponds to the length of the slice period separated in time from the mother laser pulse. Thus, for example, a first pulse slice 3500a can be characterized as having a pulse duration equal to a first slice period p1, and a second pulse slice 3500b can be characterized as having a pulse duration equal to a second slice period p2.

[0205] The sequentially successive slice periods may occur consecutively (i.e., one slice period begins immediately after the preceding slice period), intermittently (i.e., one slice period begins after a delay immediately following the preceding slice period), or a combination thereof. When the sequentially successive slice periods occur intermittently, it will be appreciated that the length of the delay can be characterized as an integer multiple of the positioning period of the first positioner 106 (this integer may be any integer, such as 1, 2, 3, 4, 5, 10, 20, 50, 100, etc., or any value therebetween). The embodiment shown in FIG. 35 is an example in which the sequentially successive slice periods p1 and p2 occur intermittently. The total time applied to the common mother laser pulse from the start of the first slice period to the end of the last slice period is less than or equal to the pulse duration of the mother laser pulse (based on the full width at half maximum (FWHM) of the optical power with respect to time). Thus, the mother laser pulse can generally be characterized as having a pulse duration longer than the positioning period of the first positioner 106. In certain embodiments, the pulse duration of the mother laser pulse is longer than, equal to, or shorter than 1 μs, 2 μs, 5 μs, 10 μs, 15 μs, 20 μs, 25 μs, 30 μs, 40 μs, 50 μs, 100 μs, 300 μs, 500 μs, 900 μs, 1 ms, 2 ms, 5 ms, 10 ms, 20 ms, 50 ms, 100 ms, 300 ms, 500 ms, 900 ms, 1 s, etc., or any value therebetween.

[0206] In one embodiment, the length of each slice period (and thus the pulse duration of each pulse slice) is an integer multiple of the positioning period of the first positioner 106 (e.g., the integer is 1, 2, 3, 5, 10, 20, 50, 100, 150, 200, 300, etc., or a value therebetween). In certain embodiments, the length of each slice period is greater than, equal to, or less than 200 μs, 125 μs, 100 μs, 50 μs, 33 μs, 25 μs, 20 μs, 13.3 μs, 12.5 μs, 10 μs, 4 μs, 2 μs, 1.3 μs, 1 μs, 0.2 μs, 0.1 μs, 0.05 μs, 0.025 μs, 0.02 μs, 0.013 μs, 0.01 μs, 0.008 μs, 0.0067 μs, 0.0057 μs, 0.0044 μs, 0.004 μs, etc., or any value therebetween. In general, the length of one or more slice periods of a mother laser pulse may be the same as or different from the length of one or more other slice periods of the same mother laser pulse. For example, although FIG. 35 illustrates the first slice period p1 as being equal to the second slice period p2, the length of the first slice period p1 may be longer or shorter than the duration of the second slice period p2.

[0207] Outside of the slicing period, the first positioner 106 may be operated by any method known in the art to attenuate the incident laser energy beam so that the laser energy beam propagating along the beam path 114 has insufficient energy to process the workpiece 102 when ultimately deflected by the first positioner 106. Additionally or alternatively, outside of the slicing period, the first positioner 106 may be operated to deflect the beam path 114 towards a beam trap, a beam dump system, or the like, or any combination thereof, as described herein or known in the art. In embodiments in which the first positioner 106 is provided as an AOD system as described herein, outside of the slice period, one or more of the AODs in the AOD system may be driven (or may not be driven as the case may be) to send the laser energy beam to a zero-order beam path (e.g., zero-order beam path 200 or 300), or to one or more higher-order beam paths (e.g., secondary beam path, tertiary beam path, etc.), or to a beam trap, or to a beam dump system (e.g., integrated beam dump system 700 or 1000, etc.), or any combination thereof, as needed.

[0208] As described above, pulse slicing can be performed in conjunction with beam splitting, or can be performed separately from beam splitting. Thus, the operation of the first positioner 106 can be controlled to deflect different pulse slices to different angles within the same primary angular range 116 (e.g., to deflect different pulse slices to the same second positioner 108), or to deflect different pulse slices to angles within different primary angular ranges 116 (e.g., to deflect different pulse slices to different positioners of the second positioner 108), or any combination thereof. For example, the operation of the first positioner 106 can be controlled to deflect the first pulse slice 3500 a and the second pulse slice 3500 b to different angles within the first primary angular range 116 a (e.g., to deflect the first pulse slice 3500 a and the second pulse slice 3500 b to the second positioner 108 a). In another example, the operation of the first positioner 106 may be controlled to deflect the first pulse slice 3500a by an angle within the first primary angular range 116a (e.g., deflect the first pulse slice 3500a to the second positioner 108a), and then deflect the second pulse slice 3500b by an angle within the second primary angular range 116b (e.g., deflect the second pulse slice 3500b to the second positioner 108b). Thus, the pulse slice 3500a having the optical power profile shown in Figure 35A can propagate to the second positioner 108a, and the pulse slice 3500b having the optical power profile shown in Figure 35B can propagate to the second positioner 108b.When the pulse slice is deflected within a primary angular range 116, the operation of the first positioner 106 may be controlled to deflect the beam path 114 (and thus the pulse slice propagating along the beam path 114) in any suitable or desired manner within any selected primary angular range 116 (e.g., to compensate for positioning errors of the second positioner corresponding to the selected primary angular range 116, or to cause relative movement along a process trajectory between the process spot and the workpiece 102a during processing of the workpiece 102, or any combination thereof).

[0209] While FIG. 35 illustrates laser pulse 3500 being temporally divided into only two pulse slices (i.e., first pulse slice 3500a and second pulse slice 3500b), it will be appreciated that laser pulse 3500 may be temporally divided into more than two pulse slices (e.g., three pulse slices, five pulse slices, eight pulse slices, ten pulse slices, twenty-five pulse slices, thirty pulse slices, fifty pulse slices, etc., or the like, or any number therebetween). For example, referring to FIG. 36, laser pulse 3500 may be temporally divided into four pulse slices 3600a, 3600b, 3600c, and 3600d. In one embodiment, operation of first positioner 106 is controlled such that successive pulse slices are deflected within different primary angular ranges 116. For example, pulse slice 3600a can be deflected into the first primary angular range 116a, then pulse slice 3600b can be deflected into the second primary angular range 116b, then pulse slice 3600c can be deflected into the first primary angular range 116a, then pulse slice 3600d can be deflected into the second primary angular range 116b. However, in other embodiments, the operation of the first positioner 106 is controlled so that successively divided pulse slices are deflected within the same primary angular range 116 or within different primary angular ranges 116. For example, pulse slice 3600a can be deflected into the first primary angular range 116a, then pulse slices 3600b and 3600c can be deflected into the second primary angular range 116b, then pulse slice 3600d can be deflected into the first primary angular range 116a.

[0210] Although pulse slicing has been described above with respect to a single mother laser pulse (i.e., laser pulse 3500), it will be appreciated that first positioner 106 may be operated to perform pulse slicing with respect to a series of successively propagating mother laser pulses, in which successive mother laser pulses may be separated in time in any desired manner, and two successive mother laser pulses may be separated in time in the same manner or in different manners.

[0211] In embodiments in which the first positioner 106 is implemented as a multi-cell AOD system, pulse slicing may be achieved by coordinated operation or actuation of at least two AODs in the multi-cell AOD system. For example, with reference to FIG. 37 , in embodiments in which the multi-cell AOD system is implemented as the AOD system 400 described above, the first AOD 402 and the second AOD 404 may be operated (e.g., as described above) during the slice period to deflect the beam path 114 within one or more of the primary angular ranges 116. The horizontal range of block 3700 indicates the period during which the first AOD 402 is operated to deflect the laser energy beam incident on the first AOD 402, and the horizontal range of block 3702 indicates the period during which the second AOD 404 is operated to deflect the laser energy beam incident on the second AOD 404. In FIG. 37, the horizontal extent of blocks 3700 and 3702 is equal to a slice period (eg, the first slice period p1, second slice period p2, etc. described above).

[0212] However, in other embodiments, one or both of the first AOD 402 and the second AOD 404 may be operated for a period longer than the slice period to deflect the beam path 114 within one or more of the primary angular ranges 116, but such that the periods during which they are driven overlap for a period equal to the slice period. See, for example, Figures 38, 39, 40, and 41.

[0213] iii. Discussion on diffraction efficiency As used herein, the term “diffraction efficiency” refers to the fraction of energy in a laser energy beam incident on an AOD that is diffracted into a first-order beam within the AO cell of the AOD. Thus, diffraction efficiency may be expressed as the ratio of the optical power of the first-order beam generated by the AOD to the optical power of the incident laser energy beam incident on the AOD. In general, the amplitude of an applied RF drive signal may have a nonlinear effect on the diffraction efficiency of an AOD, and the diffraction efficiency of an AOD may also vary as a function of the frequency of the RF drive signal applied to drive the AOD. In view of the above, in an embodiment in which the first positioner 106 is provided as the AOD system 400 described above, the first RF drive signal applied to drive the first AOD 402 may be characterized as having a certain amplitude (also referred to herein as the “first amplitude”), and the second RF drive signal applied to drive the second AOD 404 may be characterized as having a certain amplitude (also referred to herein as the “second amplitude”).

[0214] Generally, the first amplitude may be selected or set based on one or more factors such as a first drive frequency of the first RF drive signal, a first frequency range to which the first drive frequency belongs, a desired diffraction efficiency when the first AOD 402 is driven by the first RF drive signal, a peak optical power of the laser energy beam deflected during the period when the first AOD 402 is driven by the first RF drive signal, an average optical power of the laser energy beam deflected during the period when the first AOD 402 is driven by the first RF drive signal, or any combination thereof. Similarly, the second amplitude may be selected or set based on one or more factors such as the second drive frequency of the second RF drive signal, the second frequency range to which the second drive frequency belongs, the desired diffraction efficiency when the second AOD 404 is driven by the second RF drive signal, the peak optical power of the laser energy beam deflected during the time period when the second AOD 404 is driven by the second RF drive signal, the average optical power of the laser energy beam deflected during the time period when the second AOD 404 is driven by the second RF drive signal, etc. When the AOD system 400 is operated to perform pulse slicing (e.g., as described above), the first amplitude, the second amplitude, or a combination thereof may be selected or set as needed based on the desired pulse duration of the pulse slice separated in time from the laser energy beam.

[0215] In embodiments in which the AOD system 400 is driven to perform beam splitting (e.g., as described with respect to any of FIGS. 3, 31, 32, 33, or 34), the first RF drive signal can be characterized as having a first amplitude a1a if the first RF drive signal has a first drive frequency f1 within the first frequency range 3102a. Similarly, the first RF drive signal can be characterized as having a first amplitude a1b if the first RF drive signal has a first drive frequency f1 within the first frequency range 3102b. In this case, the first amplitude a1a can be higher than the first amplitude a1b. Alternatively, the first amplitude a1a can be lower than or equal to the first amplitude a1b. Similarly, if the second RF drive signal has a second drive frequency f2 within the second frequency range 3104a, the second RF drive signal can be characterized as having a second amplitude a2a, and if the second RF drive signal has a second drive frequency f2 within the second frequency range 3104b, the second RF drive signal can be characterized as having a second amplitude a2b. In this case, the second amplitude a2a can be lower than the second amplitude a2b. Alternatively, the second amplitude a2a can be higher than or equal to the second amplitude a2b.

[0216] When operating the AOD system 400 to perform beam splitting (e.g., as described above), the first amplitude of the first RF drive signal may be selected so that the optical power of the laser energy beam propagating along the primary beam path 114′ deflected within the first AOD angular range 406 a is higher than, lower than, or at least substantially equal to, the optical power of the laser energy beam propagating along the primary beam path 114′ deflected within the first AOD angular range 406 b. The first amplitude of the first RF drive signal may vary or may be maintained at a constant (or at least substantially constant) level while the primary beam path 114′ is deflected within either the first AOD angular range 406 a or 406 b. Similarly, the second amplitude of the second RF drive signal may be selected so that the optical power of the laser energy beam propagating along the primary beam path 114" deflected within the second AOD angular range 408a is higher than, lower than, or at least substantially equal to, the optical power of the laser energy beam propagating along the primary beam path 114" deflected within the second AOD angular range 408b. The second amplitude of the second RF drive signal may vary or may be maintained at a constant (or at least substantially constant) level while the primary beam path 114" is deflected within either the second AOD angular range 408a or 408b.

[0217] IV. Conclusion The foregoing describes embodiments and examples of the present invention and is not to be construed as limiting thereof. While several specific embodiments and examples have been described with reference to the drawings, those skilled in the art will readily recognize that many modifications to the disclosed embodiments and examples and other embodiments are possible without materially departing from the novel teachings and advantages of the present invention. Accordingly, all such modifications are intended to be included within the scope of the present invention as defined in the claims. For example, those skilled in the art will understand that the subject matter of any sentence, paragraph, example, or embodiment can be combined with part or all of the subject matter of any other sentence, paragraph, example, or embodiment, except where such combinations are mutually exclusive. Therefore, the scope of the present invention should be determined by the following claims and any equivalents of such claims to be included therein.

Claims

1. a first optical component that is a transmissive optical component that is transmissive to a laser energy beam, the first optical component being susceptible to thermal lensing caused by the transmissive laser energy beam; wavefront compensation optics configured to compensate for wavefront aberrations in the laser energy beam due to the thermal lensing effect within the first optical component; an optical relay system arranged and configured to relay an image of the first optical component to the wavefront compensation optic; Equipped with The optical relay system includes: configured such that a size of the image of the first optical component at the wavefront compensation optics is different from a size of the image of the first optical component at the first optical component. system.

2. 2. The system of claim 1, wherein a size of the image of the first optical component at the wavefront compensation optics is larger than a size of the image of the first optical component at the first optical component.

3. The system of claim 1 , wherein the wavefront compensating optic is configured to transmit the laser energy beam.

4. The system of claim 1 , wherein the wavefront compensating optic is configured to reflect the laser energy beam.

5. The system of claim 1 , wherein the wavefront compensation optic comprises a static wavefront compensation optic.

6. The system of claim 1 , wherein the wavefront adaptive optic comprises a dynamic wavefront adaptive optic.

7. a second optical component that is a transmissive optical component that is transmissive to the laser energy beam; the optical relay system is arranged and configured to relay an image of the first optical component at the wavefront compensation optic to the second optical component. The system of claim 1 .

8. 8. The system of claim 7, wherein the optical relay system is configured such that a size of the image of the first optical component at the wavefront compensation optics is the same as a size of the image of the first optical component at the second optical component.

9. the wavefront compensating optic is configured to reflect the laser energy beam; The optical relay system includes: a first optical relay including two lenses configured to relay the image of the first optical component to the wavefront compensation optic; a second optical relay including two lenses configured to relay the image of the first optical component at the wavefront compensation optic to the second optical component; and Including, The system of claim 7.

10. 10. The system of claim 9, wherein the first optical relay and the second optical relay share a common lens.

11. The system of claim 9 , wherein the optical relay system further includes at least one mirror disposed between two lenses of the second optical relay.

12. The system of claim 7 , wherein the second optical component is susceptible to thermal lensing caused by the transmissive laser energy beam.

13. 13. The system of claim 12, wherein the wavefront compensating optics is further configured to compensate for wavefront aberrations in the laser energy beam due to the thermal lensing effect within the second optical component.

14. The system of claim 1 , wherein the first optical component comprises an acousto-optic (AO) cell.

15. The system of claim 7 , wherein the second optical component comprises an acousto-optic (AO) cell.

16. The system of claim 1 , wherein the wavefront compensating optic is disposed optically downstream of the first optical component.

17. The system of claim 1 , wherein the wavefront compensating optic is disposed optically upstream of the first optical component.

18. a first optical component and a second optical component, each of which is a transmissive optical component capable of transmitting a laser energy beam and which is susceptible to thermal lensing caused by the transmissive laser energy beam; wavefront compensation optics configured to compensate for wavefront aberrations in the laser energy beam due to the thermal lensing effect within the first optical component and the second optical component; an optical relay system arranged and configured to relay an image of the first optical component to the wavefront compensation optic; Equipped with the wavefront compensating optic is located on a beam path along which the laser energy beam can propagate from the first optical component to the second optical component; The optical relay system is configured such that a size of the image of the first optical component at the wavefront compensation optic is different from a size of the image of the first optical component at the first optical component.

19. a first optical component and a second optical component, each of which is a transmissive optical component capable of transmitting a laser energy beam and which is susceptible to thermal lensing caused by the transmissive laser energy beam; wavefront compensation optics configured to compensate for wavefront aberrations in the laser energy beam due to the thermal lensing effect within the first optical component and the second optical component; an optical relay system arranged and configured to relay an image of the wavefront compensation optic to the second optical component; Equipped with The wavefront compensating optic is positioned on a beam path along which the laser energy beam can propagate from the first optical component to the second optical component.

20. 20. The system of claim 19, wherein the optical relay system is configured such that a size of the image of the wavefront compensation optic at the second optical component is different from a size of the image of the wavefront compensation optic at the wavefront compensation optic.

21. a first optical component and a second optical component, each of which is a transmissive optical component capable of transmitting a laser energy beam and which is susceptible to thermal lensing caused by the transmissive laser energy beam; wavefront compensation optics configured to compensate for wavefront aberrations in the laser energy beam due to the thermal lensing effect within the first optical component and the second optical component; a first optical relay including two lenses configured to relay an image of the first optical component to the wavefront compensation optic; a second optical relay including two lenses configured to relay the image of the first optical component at the wavefront compensation optic to the second optical component; and A system comprising:

22. 22. The system of claim 21, wherein the first optical relay and the second optical relay share a common lens.

23. a first optical component and a second optical component, each of which is a transmissive optical component capable of transmitting a laser energy beam and which is susceptible to thermal lensing caused by the transmissive laser energy beam; wavefront compensation optics configured to compensate for wavefront aberrations in the laser energy beam due to the thermal lensing effect within the first optical component and the second optical component; Equipped with The system, wherein the first optical component and the second optical component each include an acousto-optic (AO) cell.

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