Laser-processing apparatus, methods for operating the same, and methods of processing workpieces using the same

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 DISCLOSURE 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, polish, roughen, carbonize, foam, or 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), may be laser processed to form vias therein. Rapid processing of a workpiece may require the use of a high power laser source to generate the laser energy, rapid changes in the location of the workpiece to which the laser energy is applied, and rapid changes in the properties of the laser energy (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 range 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 wavelength infrared range of the electromagnetic spectrum). It is with respect to these and other problems discovered by the inventors that the embodiments described herein have been developed.

[0004] One embodiment of the present invention may be characterized as a laser processing apparatus including a laser source capable of generating a beam of laser energy propagable 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 within a second primary angular range. The second primary angular range does not overlap with the first angular range 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 to 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 that includes 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 may be characterized as an integrated beam dump system comprising a frame having a first surface and at least one second surface, the first surface may be configured to reflect a laser energy beam, and the at least one second surface may be configured to absorb the laser energy beam.

[0007] Another embodiment of the invention comprises a mirror having a reflective surface, the shape of which can be characterized as a wavefront correcting optic 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 invention can be characterized as a wavefront correction optic 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 invention can be characterized as a wavefront correction optic 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 invention can be characterized as a wavefront correcting optics 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 invention may be characterized as a system including a first optical component transmissible 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, and an optical relay system arranged and configured to relay an image of the first optical component at a first plane to a second plane. The wavefront compensation optic may be located at the second plane. The first optical relay system may be configured such that a size of the image of the first optical component at the second plane is different from a 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 shrink an 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 an 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 an 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 propagable 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 and 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 description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram of a multi-head laser processing apparatus according to an embodiment. [Figure 2-3] 2 and 3 illustrate diagrammatically a beam path deflection scheme that can be realized using the first positioner according to an embodiment. [Figure 4] FIG. 4 illustrates a schematic 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 diagrammatically how a beam dump system according to an embodiment can be integrated into the first positioner. [Figure 7] 7 is a schematic 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 mutually orthogonal. [Figure 8-9] 8 and 9 are perspective views illustrating exemplary beam paths through which laser energy can propagate and be trapped within the integrated beam dump system shown in FIG. [Figure 10] 10 is a perspective view in an arbitrary u / v / w coordinate system, which shows a schematic diagram of an integrated beam dump system according to another embodiment, in which the u-axis, v-axis, and w-axis are mutually orthogonal. [Figure 11-14] 11 through 14 are perspective views illustrating exemplary beam paths through 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 ratios) of the fringe Zernike polynomials on temperature for 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 diagram illustrating a 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 of which is connected to a base. [Figure 20-24] 20, 21, 22, 23, and 24 show an optical relay system according to an embodiment. [Diagram 25] FIG. 25 illustrates an optical mount according to one embodiment. [Figure 26-29] 26, 27, 28, and 29 are schematic diagrams of beam path assemblies incorporating dispersion compensators according to certain embodiments. [Diagram 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 example frequency ranges over which the first and second AODs of the first positioner may be driven in accordance with certain embodiments. [Figure 35-41] 35, 35A, 35B, 36, 37, 38, 39, 40, and 41 illustrate schematic diagrams of an approach for performing pulse slicing according to one embodiment. Detailed Description

[0016] Hereinafter, examples of embodiments will 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 are exaggerated for ease of understanding. 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 drawings. Also, elements without reference numbers may be described with reference to other drawings.

[0017] The terms used in the specification are for the purpose of describing certain exemplary embodiments only and are not intended to be limiting. Unless otherwise defined, all terms (including technical and scientific terms) used in this specification 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 indicates otherwise. Furthermore, it should be understood that the terms "comprises" and / or "comprising", when used herein, specify the presence of the 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 described, 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 only used 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, formulations, 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 errors, and the like, and other factors known to those of skill in the art. Spatially relative terms such as "lower," "below," "lower side," "upper," and "above" may be used herein for ease of description in describing the relationship of an element or feature to another element or feature, as depicted in the figures. It should be understood that the spatially relative terms are intended to include different orientations in addition to those depicted in the figures. For example, an element described as being "lower" or "below" another element or feature would be oriented "above" the other element or feature if the object in the figure were inverted. Thus, the exemplary term "lower" may include both an upper and lower orientation. If the object is otherwise oriented (e.g., rotated 90 degrees or at another orientation), the spatially relative descriptors used herein may be interpreted accordingly.

[0019] Section headings used herein, unless specifically noted, 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 the present disclosure should not be construed as being limited to the example embodiments described 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 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments described herein generally relate to methods and apparatus for laser processing (or more simply, "machining") a workpiece. Generally, processing is 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 prior to or during processing, or may be entirely internal to the workpiece (i.e., not external to the workpiece) prior to or during processing.

[0021] Specific examples of processes that may be performed with the disclosed laser processing apparatus include drilling vias or other holes, 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. Features such as openings, slots, vias, holes, etc. may have any suitable or desirable shape when viewed from the top (e.g., circular, oval, square, rectangular, triangular, tubular, or the like, or any combination thereof). Furthermore, features such as openings, slots, vias, holes, etc. may extend completely through the workpiece (e.g., forming so-called "through vias", "through holes", etc.) or may extend only partially through the workpiece (forming so-called "blind vias", "blind holes", etc.).

[0022] The workpieces that may be machined may 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), fluorinated tetraethyl 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, polymer 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, and the like, or any combination thereof, lenses, mirrors, turbine blades, powders, films, foils, plates, forms (e.g., wax molds, forms for injection molding and investment casting processes, and the like), textiles (woven fabrics, felt, and the like), surgical instruments, medical implants, packaged products, shoes, bicycles, automobiles, automobile or aviation parts (e.g., frames, body panels, and the like), appliances (e.g., microwave ovens, ovens, refrigerators, and the like), device housings (e.g., for watches, computers, smartphones, tablet computers, wearable electronic devices, and the like, or any combination thereof).

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

[0025] With reference to the embodiment shown in FIG. 1, a laser processing apparatus 100 (also referred to herein simply as the “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 number of second positioners (e.g., second positioners 108a and 108b, each collectively referred to as “second positioners 108”), a third positioner 110, and a number 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 including only one second positioner 108, or may also be applied to 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 referred to collectively herein as "scan heads 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 the like, 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 in order 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 the laser energy in the laser energy beam as it propagates from the laser source 104 to the scan lens 112. In deflecting the beam path 114 to the second positioner 108a, the beam path 114 may be deflected at 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 may 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." In general, 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 of the primary angular ranges 116 is referred to herein as "beam divergence."

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

[0030] Laser energy deflected onto the scan lens 112 is typically focused by the scan lens 112 to impinge on the 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 the workpiece 102 can be characterized as having a Gaussian spatial intensity profile or a non-Gaussian (or "shaped") spatial intensity profile (e.g., a "top hat" spatial intensity profile, a super-Gaussian spatial intensity profile, etc.).

[0031] 1 shows multiple workpieces 102 arranged to intersect different beam axes, 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 shows multiple scan lenses 112 arranged to transmit laser energy propagating along beam paths deflected by different second positioners 108, it will be appreciated that apparatus 100 may be configured (e.g., using mirrors, prisms, beam splitters, etc., or any combination thereof) such that laser energy propagating along beam paths deflected by multiple second positioners 108 is transmitted through a common scan lens 112.

[0032] As used herein, the term "spot size" refers to the diameter or maximum spatial width of the laser energy beam impinging on a region of the workpiece 102 that is at least partially processed by the impinging laser energy beam at a location where the beam axis intersects the region (also called a "process spot," "spot location," or simply a "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 applied to 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 applied to 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), and the like, 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 comprised of a collection of transparent materials (which may be coated with anti-reflective coatings, etc., as appropriate) 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. Thus, the laser source 104 may include a pulsed laser source, a CW laser source, a QCW laser source, a burst mode laser, etc., or any combination thereof. When 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, but 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 generating 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, the laser source 104 may be broadly characterized as capable of generating a beam of laser energy, which may be represented as a series of laser pulses, or as a continuous or quasi-continuous laser beam, which may then propagate along the beam path 114. Although many of the embodiments described herein refer to laser pulses, it should be understood that a continuous or quasi-continuous beam may alternatively or additionally be used where appropriate or desired.

[0035] The laser energy output by the laser source 104 may have one or more wavelengths in the ultraviolet (UV), visible, or infrared (IR) portions of the electromagnetic spectrum. Laser energy in the UV portion 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 any wavelength between these values. Laser energy in the visible green portion 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 any wavelength between 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 duration (i.e., based on the full width at half maximum (FWHM) of the optical power in the pulse versus time) ranging from 10 fs to 900 ms, however, it will be understood that the pulse duration may be shorter than 10 fs or longer than 900 ms. In this manner, the at least one laser pulse output by the laser source 104 may be any of the following: 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 a value between any of these values.

[0037] The laser pulses output by the laser source 104 can have an average power in the range of 5 mW to 50 kW. However, it will be appreciated 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 the laser source 104 at a pulse repetition rate ranging from 5 kHz to 5 GHz. However, it will be appreciated that the pulse repetition rate may be less than 5 kHz or greater than 5 GHz. Thus, laser pulses may be output by the 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 irradiated to the workpiece 102 may be characterized by one or more other characteristics, such as pulse energy, peak power, etc. Such characteristics may include the optical intensity (W / cm2) sufficient to process the workpiece 102 (e.g., to form one or more features). 2 (measured in J / cm2) and fluence (J / cm2) 2 The laser beam may be selected (e.g., based on one or more other characteristics, such as wavelength, pulse duration, average power, pulse repetition rate, etc., as desired) to irradiate a process spot on the workpiece 102, such as at a wavelength of 100 nm (measured in Hz).

[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 mode-locked solid bulk or fiber lasers, dye lasers, mode-locked diode lasers, pulsed lasers (e.g., ms pulsed lasers, ns pulsed lasers, ps pulsed lasers, fs pulsed lasers), CW lasers, QCW 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, QCW mode, pulsed mode, or any combination thereof). Specific examples of laser sources that may 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), 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 manufactured by COHERENT, 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 manufactured by TRUMPF (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, FCPAμJEWEL 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 / or 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 (including, for example, GPLN-100-M, GPLN-500-QCW, GPLN-500-M, GPLN-500-R, GPLN-2000-S, etc.), manufactured by PHOTONICS, or the like, or any combination thereof.

[0041] B. First Positioner In general, the first positioner 106 is capable of moving the beam axis 118 relative to the workpiece 102 along an X-axis (or X-direction), a 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 length of each of the first branching period and the second branching period may 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 (which can be an integer of 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 one embodiment, 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 a value between any of 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 the laser pulse in the laser energy beam. However, in other embodiments, one or more branching periods may have a duration less than the pulse duration of the laser pulse in the laser energy beam. In such embodiments, the beam branching may result in the laser pulse being split in time. Thus, this beam branching may also be referred to as "pulse slicing." Pulse slicing is described in more detail below, and may be performed in conjunction with or separate from the 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 within the second primary angular range 116b). Thus, pulse slicing may be performed in conjunction with or separate from the beam branching. The periods over which the laser pulses are separated in time may 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 may be similarly 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 a process spot within a first scan area projected by the scan lens 112. In general, 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 in either the X or Y direction 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. As used herein, the term “beam size” refers to the diameter or width of the laser energy beam, the diameter or width 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 in other directions) may be greater than, equal to, or less than a corresponding maximum dimension (measured in the XY plane) of a feature (e.g., an 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 generally includes an AO cell formed from a material such as crystalline germanium (Ge), gallium arsenide (GaAs), pyrite (PbMoO4), tellurium dioxide (TeO2), quartz, vitreous SiO2, arsenic trisulfide (As2S3), lithium niobate (LiNbO3), or the like, or any combination thereof. The EOD of an EOD system generally 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 may be considered to be a type of transmissive optical component.

[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 (and thereby moves the beam axis) the process spot to any location 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." In this specification, the inverse of the first positioning rate is referred to as the "first positioning period" and means the shortest time it takes for the position of the process spot to change from one location in the first scan area to another location in 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., 1, 2, 3, 4, 5, 6, etc.) single-element AOD, at least one (e.g., 1, 2, 3, 4, 5, 6, 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 means 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 or along the Y-axis, or along any combination thereof) by deflecting the beam path 114 in a corresponding manner. In general, 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 a 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 a beam axis along one axis (e.g., along the X-axis) and a second AOD (e.g., a single-element or multi-element AOD system) capable of deflecting a 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 a 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 technologies (e.g., AODs, AOMs, etc.) utilize the diffraction effect caused 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) that is 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, and may also include other diffraction peaks of higher orders (e.g., second order, third order, etc.). As is 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 beam, etc.) propagate along different beam paths as they exit the AO cell (e.g., through the optical output side of the AO cell). For example, the zero order beam propagates along a zero order beam path, the first order beam propagates along a 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. The 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 the way in which an incident light wave is diffracted. For example, the frequency of a given RF drive signal determines the angle at which the beam path 114 is deflected. As known in the art, the angle Θ at which the beam path 114 is deflected can be calculated as follows:

number

[0050] The first beam path exiting the AO cell can typically be considered as 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 first 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. Thus, the AOD deflects the incident beam path 114 within a plane (also referred to herein as the “deflection plane”) that includes (or is otherwise substantially parallel to) the diffraction axis of the AO cell and the optical axis within the AO cell. The spatial extent 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. Thus, 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 can be considered to correspond to the combined scan area of ​​the multiple AODs (e.g., if the first positioner 106 includes multiple AODs).

[0051] It will be appreciated that the materials forming the AO cell will depend on the wavelength of the laser energy propagating along the 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] Beam axis movement by the second positioner 108 relative to the workpiece 102 is generally limited to scan, move, or position a process spot within a second scan area projected by the scan lens 112. In general, the second scan area may extend a greater distance in either the X or Y direction 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., an 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] In general, the positioning speed at which the second positioner 108 can position the process spot anywhere within the second scan region (thereby moving the beam axis within the second scan region and / or scanning the first scan region within the second scan region) 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 yet 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 can move the workpiece 102 (e.g., workpieces 102a and 102b) relative to the scan lens 112, which can then move 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 a 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 can extend in the X direction, the Y direction, or any combination thereof, to a distance greater than or equal to the corresponding distance of the second scan area. However, in general, 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, the 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 the 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. In general, 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 500 Hz (or about). For example, the third positioning bandwidth may be equal to or lower than 500Hz, 250Hz, 150Hz, 100Hz, 75Hz, 50Hz, 25Hz, 10Hz, 7.5Hz, 5Hz, 2.5Hz, 2Hz, 1.5Hz, 1Hz, 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 rotational 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 primary 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 discussed, the apparatus 100 may use a so-called “stacked” positioning system for the third positioner 110, which allows the workpiece 102 to be moved while the positions of other components, such as the first positioner 106, the second positioner 108, the scan lens 112, etc., remain stationary within the apparatus 100 relative to the workpiece 102 (e.g., via one or more supports, frames, etc., as known in the art). In other embodiments, the third positioner 110 may be arranged and operated to move one or more components, such as the first positioner 106, the second positioner 108, the scan lens 112, etc., or any combination thereof, and the 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 to move the workpiece 102 along a Y direction and an X stage to move the scan head along an X direction. Examples of split-axis positioning systems that may be beneficially or advantageously utilized in apparatus 100 include any 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 in 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 or may carry one or more of the other stages described above for moving or positioning the workpiece 102, or any combination thereof. In another embodiment 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 at the workpiece 102.

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

[0065] D. Scan Lens In general, 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 generate 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 generated 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 generated 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) capable of moving the scan lens 112 (e.g., to change the position of the beam waist along the beam axis). For example, the lens actuator may be provided as a voice coil capable of linearly translating the scan lens 112 along the Z direction. In this case, the scan lens 112 may be formed from materials such as fused silica, optical glass, zinc selenide, zinc sulfide, germanium, gallium arsenide, magnesium fluoride, etc. In another embodiment, 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. By changing the position of the beam waist along the beam axis, the spot size at the workpiece 102 can be changed.

[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 moveable relative to the housing in which second positioner 108 is integrated).

[0068] F. Controller Generally, the apparatus 100 includes one or more controllers, such as controller 122, for controlling or facilitating the control and operation of the apparatus 100. In one embodiment, the 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, or the like, or any combination thereof) to one or more components of the apparatus 100, 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., such that these components operate in response to one or more control signals output by the 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 motion 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 motion between the process spot and the workpiece 102 (thereby effecting a “compound relative motion” between the beam axis and the workpiece). Of course, at any one time, it is also possible to control only one positioner (e.g., the first positioner 106, the second positioner 108 or the third positioner 110) to cause relative motion between the process spot and the workpiece 102 (thereby causing "non-compound relative motion" between the beam axis and the workpiece).

[0070] In one embodiment, 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 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 motion 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 motion between the process spot and the workpiece 102a along a first process trajectory within the workpiece 102a. Similarly, the 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 in conjunction with 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 the tracking error introduced by the corresponding second positioner 108. For example, the operation of the first positioner 106 can be controlled to deflect the beam path 114 within the first primary angular range 116a in a manner that compensates for the tracking error introduced by the corresponding second positioner 108a. Similarly, the operation of the first positioner 106 can be controlled to deflect the beam path 114 within the second primary angular range 116b in a manner that compensates for the tracking error 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-mentioned 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, 6,3 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, 2014 / 01962140, 2014 / 0196351 ... 014 / 0263201, 2014 / 0263212, 2014 / 0263223, 2014 / 0312013, or in German Federal Patent Publication 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 positioners, including one or more AODs (e.g., in an 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 in, for example, International Patent Publication No. WO2017 / 044646A1, 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 chirped 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 generate the control signals described above upon execution of instructions. The processor may be provided as a programmable processor (e.g., including 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, 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 be performed 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 drive, etc.), optical disks, volatile or non-volatile semiconductor memory (e.g., RAM, ROM, NAND flash memory, NOR flash memory, SONOS memory, etc.), and the like, which may be locally accessible or remotely accessible (e.g., over a network), or any combination thereof. In general, 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 language (e.g., VHDL, VERILOG, etc.), etc., and may be readily produced by one of ordinary skill in the art from the description set forth 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. Thus, 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 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, which is capable of generating one or more control signals (e.g., trigger signals, etc.) that may be sent to inputs of one or more drivers associated with one or more components of the device 100. In this manner, 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), and the fixtures 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 be communicatively coupled to inputs of drivers communicatively coupled to (and associated with) 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., as desired. In this embodiment, each component-specific controller may be communicatively coupled to the 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 the 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 controllers may be operable in a manner similar to that described with respect to the 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 of an embodiment 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 inverting 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 provide 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 the applied RF drive signal (e.g., in response to an applied RF drive signal having a particular frequency) without inverting 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 may be oriented such 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, the wavelength of the laser energy beam is in the ultraviolet or visible green region of the electromagnetic spectrum, the AO cells of the AOD are formed from a material such as quartz, and the AOD may be oriented such 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, where 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 the 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 a "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 axis of rotation to transmit the first order beam propagating along a deflected beam path 114". As can be appreciated, each of beam path 114' and beam path 114" represent specific examples of paths along which a laser energy beam may propagate. Accordingly, each of beam path 114' and beam path 114" may also be collectively referred to herein as "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 can be positioned in the beam path 114' to rotate the deflection plane of the first AOD 402 (e.g., by 90 degrees or thereabouts) such that the deflection plane of the first AOD 402 is rotated (e.g., by 90 degrees or thereabouts) relative to the direction of the deflection plane of the second AOD 404 when projected onto 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 or different from the AO cells in the second AOD 404. Additionally, the type of acoustic waves (i.e., shear or longitudinal modes) that the first AOD 402 uses to polarize an 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 an incident laser energy beam.

[0084] It will be appreciated that at any given time the AOD system 400 may be operated such 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 may 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 a superposition of the deflections obtained from beam paths 114' and 114". Similarly, the primary angular range 116 may be considered to be solely the first AOD angular range 406, or solely the second AOD angular range 408, or a 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 sent 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 preferred 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 the first AOD 402, and the thermal load on the two AODs is often relatively equal, keeping the first AOD 402 on for the entire pulse duration may increase the average thermal load on the first AOD 402 and the second AOD 404. The increased thermal load on the AODs may result in potentially undesirable beam distortions (e.g., due to thermal lensing).

[0086] Notwithstanding the above, directing a 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 a 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 a 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, as required, 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, or the like, or any combination thereof.

[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. Traditionally, undesired laser energy propagating from the AOD is diverted using a pick-off mirror that reflects the laser energy (e.g., at its reflective surface) to a remote beam trap. The laser energy may be reflected directly from the pick-off mirror into the beam trap, or 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] 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 the zeroth order beam path 300 and the 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 a beam path, such as any of the beam paths 502, while continuing to propagate the laser energy propagating along the zeroth order beam path 300 and the first order beam path 114', respectively (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 the "second beam dump system") disposed 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 a 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 the zero order beam path 300 may propagate from the second AOD 404 along the 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 the 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, and the like, or any combination thereof.

[0092] i. Example of Beam Dump System Embodiments In one embodiment, the pick-off mirrors and the beam traps 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 above potential problems associated with separate components in a beam dump system, other embodiments of the beam dump system may integrate the pick-off mirrors, beam traps, and intervening relay mirrors (pre-aligned as necessary) into a common package. Such a beam dump system (also referred to herein as an "integrated beam dump system") can be easily integrated into a beam path assembly by any suitable method known in the art. The only alignment required then 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 separate pick-off mirrors, one or more beam traps, and optionally one or more relay mirrors between the pick-off mirrors and the beam traps, all mounted (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, carbon fiber reinforced polymer composites, etc., that provides a flat surface onto which optical components can be mounted (e.g., by screws, adhesives, clamps, etc., or any combination thereof). The optical breadboard is then mounted into 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, carbon fiber reinforced polymer composite, etc.), in which case the frame has 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, etc., 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, etc., 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, relay mirror, or any combination thereof), one or more light absorbing surfaces or structures (e.g., suitable to function as or part of a beam trap), 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 other examples, where 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 other examples, 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 the laser energy may cause the beam trap to heat up in an undesirable manner. Thus, 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, and 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 other embodiments, the one or more cooling systems may be integral to or mechanically coupled to the optical breadboard or frame.

[0099] ii. Example embodiments of integrated beam dump systems 7, an integrated beam dump system such as integrated beam dump system 700 may include a frame 702 formed from a material such as steel, brass, aluminum or aluminum alloy, copper or copper alloy, or the like, or any combination thereof. Frame 702 may be formed by any suitable or desired process known in the art (e.g., CNC milling, casting, welding, or the like, or any combination thereof) to form a plurality of surfaces such as surfaces 704, 706, 708, 710, 712, 714, 716. Generally, surfaces 704, 706, 708 are provided as reflective surfaces, and surfaces 710, 712, 714, 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 may function as pick-off mirrors, surface 708 may function as a relay mirror, and surfaces 710, 712, 714, 716 may 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 towards surface 708 , which reflects the redirected laser energy towards beam trap 718 .

[0100] Surfaces 704, 706, and 708 may be made reflective during or after formation of frame 702. For example, after frame 702 is formed, surfaces 704, 706, and 708 may be made reflective by subjecting the area of ​​frame 702 in which 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 by any combination thereof.

[0101] Surfaces 710, 712, 714, and 716 can be made absorbent during or after formation of frame 702. For example, frame 702 can be formed such that surfaces 704, 706, 708, 710, 712, 714, and 716 are reflective, and then surfaces 704, 706, and 708 can be masked to prevent a subsequent process applied to frame 702 (e.g., one or more etching, roughening, oxidation, anodizing, coating, and the like, or any combination thereof) from rendering surfaces 704, 706, and 708 optically absorbent. 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 are known in the art. After the surfaces 704, 706, and 708 are appropriately masked, the 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 the surfaces 704, 706, and 708, which are still reflective.

[0102] In one embodiment, frame 702 may 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 may be anodized to form an anodized layer of sufficient thickness to at least partially (or at least substantially) absorb an incident laser energy beam. Generally, the minimum thickness of the anodized layer required to provide the desired optical absorption of the 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 suitably absorb laser energy at a wavelength of 9.4 μm. After anodizing frame 702, the areas of frame 702 in which one or more of faces 704, 706, 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 frame 702 is anodized, 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] 8, surface 704 may act as a pick-off mirror to redirect laser energy propagating along an undesired beam path (e.g., beam path 800 propagating from the first AOD 402 or the second AOD 404) to surface 708. Surface 708 may act as a relay mirror to reflect laser energy reflected from surface 704 to beam trap 718 (e.g., to surface 716) where the laser energy is absorbed. Although 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 at surface 716. In this case, the laser energy reflects from surface 716 to surface 712, and the remaining energy is either fully absorbed or partially reflected back to surface 716 where it is at least partially absorbed.

[0104] Similarly, with reference to FIG. 9 , surface 706 may act as a pick-off mirror to redirect 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 act 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. Although 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 fully absorbed or partially reflected back to surface 710 where it is at least partially absorbed.

[0105] Returning to FIG. 7, the frame 702 may further include an aperture 720 that serves as an optical input for the integrated beam dump system 700. As shown, the aperture 720 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 paths 114 or 300 as shown in FIG. 7, or along other beam paths such as beam paths 800 or 900 as shown in FIG. 8 or FIG. 9, respectively, or along any combination thereof) to pass therethrough. The frame 702 may further include apertures 722 and 724 that each serve as an optical output for the integrated beam dump system 700. That is, the aperture 722 is positioned and sized to allow laser energy propagating along beam path 114 to pass therethrough. Similarly, the 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, 1020. Generally, surfaces 1004, 1006, 1008, 1010, 1012 are provided as reflective surfaces, and surfaces 1014, 1016, 1018, 1020 are provided as light absorbing surfaces. Any of the 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 the 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 pick-off 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 redirect laser energy propagating along undesired beam paths. In particular, surface 1004 is configured to reflect incident laser energy directly towards beam trap 1020, and surfaces 1006 and 1008 are configured to reflect incident laser energy towards surfaces 1010 and 1012, respectively. Surfaces 1010 and 1012 are then each configured to reflect the redirected laser energy towards beam trap 1022, respectively.

[0107] 11, surface 1004 may act 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) to surface 1014. Although FIG. 11 shows beam path 1100 as terminating at surface 1014 (thereby implying that all of the laser energy propagating along beam path 1100 is absorbed), it will be understood that some laser energy may be reflected at 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 is partially reflected back to surface 1014 and at least partially absorbed at surface 1014.

[0108] Similarly, with reference to Figure 12, surface 1008 may act 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) to surface 1014. Although Figure 12 shows beam path 1200 as terminating at surface 1016 (thereby suggesting that a portion of the laser energy propagating along beam path 1200 is reflected off 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 off 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 fully 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 to redirect laser energy propagating along an undesired beam path (e.g., beam path 1300 propagating from the first AOD 402 or the second AOD 404) to surface 1010. Surface 1010 may act as a relay mirror to reflect laser energy reflected from surface 1004 towards beam trap 1022 (e.g., towards surface 1016) where the laser energy is absorbed. Although FIG. 13 shows beam path 1300 as terminating at surface 1016 (suggesting that all of the laser energy propagating along beam path 1300 is absorbed), it will be understood that some laser energy may be reflected at surface 1016. In this case, laser energy reflects from surface 1016 to surface 1020 and the remaining laser energy is either completely absorbed at surface 1020 or partially reflected back to surface 1016 and at least partially absorbed at surface 1016 .

[0110] 14, surface 1008 may act as a pick-off mirror to redirect laser energy propagating along an undesired beam path (e.g., beam path 1400 propagating from the first AOD 402 or the second AOD 404) to surface 1012. Surface 1012 may act as a relay mirror to reflect laser energy reflected from surface 1008 towards beam trap 1022 (e.g., towards surface 1016) where the laser energy is absorbed. Although FIG. 14 shows beam path 1400 as terminating at surface 1016 (suggesting that all of the laser energy propagating along beam path 1400 is absorbed), it will be understood that some laser energy may be reflected at surface 1016. In this case, laser energy reflects from surface 1016 to surface 1020 and the remaining laser energy is either completely absorbed at surface 1020 or partially reflected back to surface 1016 and at least partially absorbed at 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, 1400 as shown in FIG. 11, FIG. 12, FIG. 13, or FIG. 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 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] It will be appreciated from the above description of integrated beam dump systems 700 and 1000 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 include one or more plates spanning the interior regions, as desired. For example, the integrated beam dump system 700 may include a first plate 726 coupled to the frame 702 (e.g., at a first side thereof), a second plate 728 (shown in dashed lines in FIG. 7 ) coupled to the frame 702 (e.g., at a second side opposite the first side) (e.g., by screws, adhesive, clamps, etc., or any combination thereof), or any 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 in dashed lines in FIG. 10 ) coupled to the frame 1002 (e.g., at a second side opposite the first side) (e.g., by screws, adhesive, clamps, etc., or any combination thereof). Although the integrated beam dump system 1000 has been described above as the frame 1002 providing the surface 1008, the surface 1008 may alternatively be provided by a block (e.g., block 1034) that is 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 the 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 for the removal of heat from the associated beam trap (i.e., beam trap 718 or 1022). In other embodiment, 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 the 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 may be desirable if 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 constructed of the same material, and if each AOD in the multi-cell AOD system uses the same type of acoustic waves to deflect an incident laser energy beam, and if it is preferable to linearize the polarization state in a primary 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 the primary beam passing through the second AOD relative to the polarization state in the primary beam passing through the first AOD, in the same way that the orientation of the second AOD is rotated relative to the orientation of the first AOD.

[0115] Examples of phase retarders that may be incorporated into the 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 may 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 may be positioned on the 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 incident on the second AOD with the diffraction axis of the AO cell within the second AOD.

[0116] D. EMBODIMENTS GENERALLY RELATING TO COMPENSATION FOR WAVEFRONT DISTORTION In many cases, a transmissive optical component absorbs a portion of the light incident on it. When the incident light is a high-power laser energy beam, the absorbed light heats the material that makes up the transmissive optical component. Sometimes, when the 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, a central region of a beam with a Gaussian spatial intensity distribution heats one region of the transmissive optical component more than a peripheral region of the beam. Because the refractive index of many materials that make up 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 the transmissive optical component may expand (as a result of thermal expansion), and such expansion may cause the shape of the transmissive optical component to approximate the shape of a lens. Also, changes in refractive index may occur due to thermally induced mechanical stresses (known as the photoelastic effect) within the transmissive optical component. 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 may be achieved by means other than absorption of laser energy. For example, the transmissive optical component may be placed in proximity to 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 may cause a differential change in the refractive index within the transmissive optical component, an effect also known as "thermal lensing." Thermal lensing may undesirably focus or defocus the laser energy beam or distort its wavefront 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 from occurring). Another approach is to simply lower the power in the laser energy beam. However, these approaches may be difficult or impossible to implement in the absence of substantially transparent transmissive optical components or in the absence of a relatively low power laser energy beam that can machine the workpiece in the desired configuration. Thus, according to embodiments described in more detail below, one or more optical components (referred to herein as "wavefront compensation 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 on 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 j-th terms of the Zernike polynomials are described using the "fringe" (also known as the "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 should 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 performed by the 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 to induce 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. For this reason, 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 the 4σ width of the laser energy beam to about twice that width are most useful (for a perfect 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 ratios) 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 beam of laser energy produced from a CO2 laser source and having a wavelength in the range of 8 μm to 12 μm and 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 changed by varying the temperature of the cooling water circulating around the germanium block. Thus, 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 coefficients 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 graph is based on observations where 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 may also be observed in other bulk transparent materials used to form AO cells, such as tellurium dioxide (depending on one or more factors, such as, for example, 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, or any combination thereof.) Additionally, 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 may also be observed in other transparent optical components, such as lenses, beam splitters, prisms, dichroic filters, windows, wave plates, DOEs, ROEs, etc. (which may be coated, as appropriate, with one or more anti-reflective coatings, etc.) formed from bulk transparent materials (e.g., depending on one or more factors, such as, 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, or any combination thereof). 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 embodiment related to wavefront compensation optics Having described the nature of the aberrations in the laser energy beam that may be caused by thermal lensing, numerous embodiments of wavefront compensation optics that may be disposed in the beam path 114 to compensate for the aberrations are described below. In general, however, the wavefront compensation 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 compensation optics is a filter that reduces the fringe Zernike terms (e.g., Z4, Z9, Z 16The shape of the reflective surface may be provided as a reflective optical component (e.g., a spherical or 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 fluidic methods (MRF polishing).

[0125] In other embodiments, the wavefront adaptive optics may be modified to include fringe Zernike terms (e.g., Z4, Z9, Z 16 The transmissive optical component may be provided as a transmissive optical component (such as a spherical lens) having a reflective surface with a shape characterized by a Z9 term, where the coefficients of the fringe Zernike terms are selected to compensate for wavefront distortions in the laser energy beam. In other embodiments, the transmissive optical component may include two or more spherical lenses set a small distance apart to produce a desired value of the coefficient for the Z9 term.

[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 of the coefficient for the Z4 term may be realized on one or more surfaces of the one or more transmissive optical components, and any amount of compensation of the coefficient for 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 compensation optics". In other embodiments, the wavefront compensation optics dynamically compensate for the effects caused by thermal lensing in the transmissive optical components and are therefore considered examples of "dynamic wavefront compensation optics". In this case, the dynamic wavefront compensation optics may include one or more variable focal length lenses or lens assemblies, one or more deformable mirrors, and one or more optically 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 by MEMS technology as appropriate), membrane deformable mirrors (i.e., comprising a reflective membrane that can be deformed mechanically, pneumatically, hydraulically, mechanically, etc., by methods known in the art), and the like. Additionally, the dynamic wavefront compensation optics may include fixed focal length lenses or lens assemblies which 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 on 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 on 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 In one embodiment, referring to FIG. 16 and FIG. 16A, 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 in 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 varying pressure within the pocket 1606. For example, referring to FIG. 17, the mirror 1600 may be coupled (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 a base 1700 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 outside 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 distortions (actual wavefront distortions, expected wavefront distortions, or any combination thereof) that it is intended to compensate for. The geometry of membrane region 1608 changes the fringe Zernike terms (e.g., Z4, Z9, Z1, Z2, Z3, Z4, Z5, Z6, Z7, Z8, Z9, Z10, Z11, Z12, Z13, Z14, Z15, Z16, Z17, Z18, Z19, Z20, Z21, Z22, Z23, Z24, Z25, Z26, Z27, Z28, Z29, Z30, Z31, Z32, Z33, Z34, Z35, Z36, Z37, Z38, Z39, Z40, Z41, Z42, Z43, Z44, Z45, Z46, Z47, Z48, Z50, Z51, Z52, Z53, Z54, Z55, Z56, Z57, Z58, Z69, Z61, Z62, Z63, Z64, Z65, Z66, Z67, Z68, Z70, Z71, Z72, Z73, Z74, Z75, Z75, Z86, Z90, Z91, Z92, Z93, Z94, Z95, Z96, Z97, Z98, Z99, Z109, Z110, Z120, Z130, Z140, Z150, Z161, Z172, Z182, Z190, 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 the 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 the controller 122 or other controller), or the like, or any combination thereof. The control element can introduce pressurized air to the pocket 1606 (e.g., when the laser source 104 is activated to generate a beam of laser energy to process the workpiece) and reduce pressure to the pocket 1606 (e.g., when the laser source 104 is turned off or 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, or the like) is typically coupled to the pedestal 1700 in fluid communication with the perforation 1704, and a second end of the hose (opposite the first end) is in fluid communication with the control element.

[0132] In one embodiment, the 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 the first positioner 106, or at a location optically between the first positioner 106 and the second positioner 108, or at a location optically downstream relative to the 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 a 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, the geometry of the membrane region 1608 may be configured in one embodiment to ensure that one or more coefficients of the fringe Zernike terms described above that can be used to characterize the shape of the reflective surface 1602 have a linear (or at least substantially linear, or positively linear) dependence on the pressure in the pocket 1606. In general, the pressure in the pocket 1606 may vary from 0 psi (or thereabouts) to 85 psi (or thereabouts). In other embodiments, the geometry of the membrane region 1608 may be configured to ensure that a ratio (also referred to herein as a "compensation ratio") between two or more coefficients of the fringe Zernike terms described above that can be used to characterize the shape of the reflective surface 1602 is within a predetermined range. For example, the geometry of membrane region 1608 may 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 may vary within the ranges discussed above based on the pressure in pocket 1606, or may be constant (or at least substantially constant) regardless of the pressure in pocket 1606.

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

[0135] In one embodiment, the 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 the 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 in the laser energy beam (either actual wavefront distortions, predicted wavefront distortions, or any combination thereof) 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 Z4 and Z9. In other embodiments, as the reflective surface 1602 deforms, the configuration of the membrane deformable mirror 1600 can be modified in any suitable manner known in the art such that the shape of the reflective surface 1602 can be suitably characterized by a single symmetric fringe Zernike polynomial (e.g., Z9).

[0138] For example, referring to FIG. 18, the membrane-type deformable mirror may be provided as mirror 1800. Mirror 1800 may be provided in a similar manner as 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 from one another by a pair of annular ribs 1808 and 1810 that extend 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 , 1806 can be formed by first machining a single cavity into 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 an adhesive, one or more welds, one or more clamps, one or more screws, or the like, 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 a number of seals extending along the peripheries of pockets 1802, 1804, 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] As shown in FIG. 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 in 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 surrounding 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, the first perforation 1812 can be coupled to a different control element than the second perforation 1816. In other examples, the first perforation 1812 and the second perforation 1816 are commonly coupled to the same control element that can pressurize or depressurize pocket 1802 relative to pocket 1806, or pressurize or depressurize pocket 1806 relative to pocket 1802, or 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 atmospheric pressure of the external 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 atmospheric pressure of the environment outside pocket 1804 by a predetermined threshold amount), the portions of membrane area 1608 exposed by pockets 1802 and 1806 deform convexly (e.g., bend outwardly away from surface 1702 of pedestal 1700), which causes the portions of membrane area 1608 exposed by pocket 1804 to deform concavely (e.g., bend inwardly toward surface 1702 of pedestal 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 deforming 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, in another embodiment, the membrane-type deformable mirror may be provided as mirror 1900. Mirror 1900 may be provided similarly 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, or the like, or any combination thereof), peripheral region 1610 and ribs 1906 of mirror 1900 are biased or sealed against surface 1702 of base 1700. This results in the formation of a number of seals that extend along the peripheries of pockets 1902 and 1904.

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

[0145] When pockets 1902 and 1904 are not fully pressurized (e.g., when the pressure within pockets 1902 and 1904 is equal to the atmospheric pressure of the external environment outside pockets 1902 and 1904), reflective surface 1602 is substantially flat. When pockets 1902 and 1904 are fully pressurized (e.g., when the pressure in each of pockets 1902 and 1904 is greater than the atmospheric 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 in a convex manner (e.g., bending outwardly away from surface 1702 of pedestal 1700). In this case, the connection between membrane region 1608 and rib 1906 acts as an annular fulcrum, which allows membrane region 1608 to deform in a convex manner as described above, and rib 1906 to deform membrane region 1608 in a concave manner as described above. The geometry of the mirror 1900 can 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 in the manner described above can be modified in any suitable manner known in the art such that the shape of the deformed reflective surface 1602 can have a variety of shapes, including but not limited to shapes 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 In general, wavefront aberrations caused by thermal lensing in a transmissive optical component occur at a specific location in 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 are corrected at the object plane (i.e., where the wavefront aberrations are generated). However, this is usually physically impossible. Therefore, the object plane is reprojected to another plane (referred to as the "image plane" or "second plane") located outside the transmissive optical component, and a wavefront compensation optic is located 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 compensation optics (i.e., to place the image plane on the wavefront compensation 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). The configuration and arrangement of the optical components in 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 of an optical relay system 20, an optical relay system such as optical relay system 2000 may include a first optical relay 2000a, a second optical relay 2000b, or a combination of the first optical relay 2000a and the second optical relay 2000b. The optical relay system 2000 is incorporated into a beam path assembly that includes a wavefront compensation optic 2002 and one or both of a first optical component 2004a and a second optical component 2004b. In general, at least one of the first optical component 2004a and the second optical component 2004b represents an optical component that may distort the wavefront of an incident laser energy beam due to thermal lensing effects (e.g., as described above). Thus, the wavefront compensation 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 2004a, or compensate for expected wavefront distortions accumulated by the laser energy beam as a result of thermal lensing in the second optical component 2004b, or a combination thereof. The wavefront compensation optic 2002 may be provided as static wavefront compensation optics, dynamic wavefront compensation optics, or the like, or any combination thereof. Generally, however, the wavefront compensation 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. Although FIG. 20 shows 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 compensation 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 compensation 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 2004a and the second optical component 2004b, but may be incorporated into a beam path assembly that includes the 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 the laser energy beam as a result of thermal lensing in the first optical component 2004a, or compensate for expected wavefront distortions accumulated by the laser energy beam as a result of thermal lensing in the second optical component 2004b, 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 compensation optic 2100 may be a membrane-type deformable mirror provided by any suitable method (exemplary of which are mentioned above).

[0152] According to the embodiment exemplarily shown in FIG. 20 and FIG. 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 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 the optical relay system 2200 may include the first optical relay 2200a and the 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 an 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 an 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 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 2200a and the second optical relay 2200b 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.

[0154] 22 illustrates first optical relay 2200a and second optical relay 2200b each 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 first optical relay 2200a and second optical relay 2200b. For example, referring to FIG. 23, optical relay system 2200 described above may be modified (thereby forming optical relay system 2300) to incorporate multiple mirrors (e.g., mirrors 2302 and 2304) disposed along beam path 114 between second lens 2204 and third lens 2206.

[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 any one or more of the transmissive optical components described above, laser gain media, 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, PbMoO4, TeO2, quartz, glassy SiO2, As2S3, LiNbO3, etc.) of any of the AOD systems described above. For example, the first optical component 2004a may be provided as an AO cell of the first AOD 402 described above. The second optical component 2004b may be provided as an 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 embodiment, the AO cells of the first AOD 402 and the second AOD 404 can both be made of 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 to be disposed 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 any combination thereof.

[0156] In the case where 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., shown in FIG. 4). Similarly, a beam dump (not shown) may be provided to absorb the zero order beam (also not shown) propagating from the first optical component 2004a. In other embodiments, the zero order beam may be allowed to propagate from the first optical component 2004a to the second optical component 2004b (e.g., 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 a beam dump system as exemplarily described above).

[0158] As exemplarily shown in Fig. 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 and is not 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. Thus, 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 (and the optical relay system 2400 may be configured) to include a lens 2402 (e.g., a single diverging lens) located 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 where 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', but 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, one or more optical elements (e.g., one or more mirrors) may be provided to transmit the zero-order beam path 300 leaving the first optical component 2004a to the first lens 2202 along a direction at least generally parallel to the first-order beam path 114' (e.g., so that the zero-order beam path 300 propagates sequentially through the second lens 2204, to the wavefront correction optics 2100, to the mirror 2302, to the mirror 2304, through the third lens 2206, and to the second optical component 2004b). In this case, the lens 2402 may be omitted from the beam path assembly. In another example, the size and position of at least one of the first lens 2202, the second lens 2204, the wavefront correction optical component 2100, the mirror 2302, the mirror 2304, and the third lens 2206 may be adjusted to be located in both the zero-order beam path 300 and the 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., may be held in place in the beam path assembly using optical mounts. The optical mounts are then typically coupled to a frame or wall of the apparatus 100, an optical breadboard integrated into the apparatus 100, or the like. Often, the mounts are configured to exert one or more compressive forces on the optical components to hold and maintain the position of the optical components over a range of environmental conditions. However, the optical surfaces of some optical components may be so sensitive to mechanical stress that even relatively small compressive forces may deform the optical surfaces in an undesirable manner. As used herein, "optical surface" may 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. Thus, in one embodiment exemplarily shown in FIG. 25, a mount 2500 for holding a membrane type deformable mirror may 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 coupling 2504 of base 1700. In one embodiment, coupling 2504 is threaded, and mount plate 2502 includes a female-threaded bore configured to screw into threaded coupling 2504. In other embodiments, coupling 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.). The mount plate 2502 may be coupled to any suitable or known fixed or adjustable optical mount assembly (not shown) in any manner known in the art (e.g., via one or more screws, clamps, springs, adhesives, etc.). In embodiments in which the coupling 2504 is threaded into a threaded hole in the mount plate 2502, the mount 2500 may also include a locking nut 2506. The locking nut 2506 may be threaded into the threaded hole in the mount plate 2502 to help lock the coupling 2504 within the threaded hole in the 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 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 be coupled 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] Although Fig. 25 shows mount 2500 as being coupled to pedestal 1700 shown in Fig. 17 (for securing mirror 1600), it will be understood that mount 2500 may be coupled to other pedestals for securing mirror 1600 or other membrane deformable mirrors. For example, mount 2500 may be coupled to pedestal 1700 shown in Fig. 18 (for securing mirror 1800) or to pedestal 1700 shown in Fig. 19 (for securing mirror 1900). Also, although mount 2500 is described above as including a pedestal for use in securing a membrane deformable mirror, it will be understood that mount 2500 may include any other suitable pedestal 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 may be spatially distorted in an undesirable manner (e.g., resulting in an undesirable form of distortion such as an elongated process spot in the workpiece 102) or may be spatially resolved into many beamlets having different wavelengths or spectral linewidths. Thus, for laser processing applications such as those described above, it is preferred that the laser energy beam ultimately incident on the AOD at the first positioner 106 has a suitably narrow spectral linewidth to minimize or eliminate the above-mentioned adverse effects of AOD intra-diffraction events on a wide linewidth laser energy beam. The spectral linewidth may 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 ranges 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) may produce laser pulses with spectral linewidths in the SWIR, MWIR, or LWIR ranges that are suitably narrow for laser processing applications in some cases. 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, a laser energy beam produced by a gas laser (e.g., a high or low power CW or pulsed carbon dioxide or carbon monoxide gas laser) lacking an appropriate spectrally selectable device may produce a laser energy beam having an undesirably broad spectral linewidth. If an AOD (e.g., incorporating an AO cell formed from crystalline germanium) is used to deflect such a beam, the AOD produces a deflected laser energy beam that may be spatially distorted or spatially resolved in an undesirable manner 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. In general, the 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 may vary depending on one or more factors, such as the wavelength of the laser energy beam propagating along the beam path 114, the beam size of the laser energy beam, etc. For example, if the laser energy beam propagating along the beam path 114 has a wavelength in the infrared region of the electromagnetic spectrum (e.g., in the MWIR or LWIR region spanning wavelengths such as 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 Embodiments In one embodiment, referring to Figure 26, a dispersion compensator 2600 is positioned on the beam path 114 at a position optically upstream of the AOD 2602. In general, 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 Figure 26, the AOD 2602 is an AOD of the first positioner 106 (e.g., the first AOD 402 or the second AOD 404).

[0168] In another embodiment, referring to FIG. 27, the dispersion compensator 2600 is disposed between components of the optical relay system on the beam path 114 at a location optically upstream of the AOD 2602. For example, the optical relay system may include a first beam expander 2700 disposed at a location optically upstream of the dispersion compensator 2600 and a second beam expander 2702 disposed at a location 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 “shrink”) the laser energy beam propagating along the beam path 114 from the dispersion compensator 2600 (e.g., from at or about 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. As with the embodiment shown in Figure 26, the AOD 2602 shown in Figure 27 is an AOD of the first positioner 106 (e.g., the first AOD 402 or the second AOD 404). If the beam size expansion provided by the first beam expander 2700 is large enough, 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 a case, referring to FIG. 28, a dispersion compensator 2600 may 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 in beam path 114.

[0170] In the embodiments shown in Figures 26 to 28, the dispersion compensator 2600 is provided as a dispersion prism (e.g., an equilateral dispersion 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 a plurality of second positioners 108 (e.g., second positioners 108a and 108b as described above in relation to FIG. 1), the beam path assembly of the apparatus 100 may correspondingly include a plurality 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 in relation 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 the beam path 114 is deflected within a first primary angular range, it is relayed through an optical port (i.e., first optical port 2906a) formed in the optical wall 2902 and then directed to the 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 the beam path 114 is deflected within a second primary angular range 116b, it is relayed through an optical port (i.e., second optical port 2906b) formed in the optical wall 2902 and then directed to the 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 the first dispersion compensator 2600a is directed to the second positioner 108a (e.g., reflected by mirror 2910a). Similarly, beam path 114 exiting the second dispersion compensator 2600b is directed to the second positioner 108b (e.g., reflected by mirror 2910b).

[0173] In the embodiment shown in Figure 29, each of the mirrors 2908a, 2908b, 2910a, 2910b is attached to the first side 2904 of the optical wall 2902. However, it will be understood that such optical components may be provided on the beam path 114 using other suitable techniques. Furthermore, it will be understood that the beam path assembly shown in Figure 29 may be provided in different configurations (e.g., with different locations of the mirrors 2908a, 2908b, 2910a, 2910b, different locations of the 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 second primary angular range 116b relative to when the first positioner 106 is operated to deflect the beam path 114 within the first primary angular range 116a.

[0174] G. Additional Beam Path Assembly Embodiments Although not shown in FIG. 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 2906a to direct the beam path 114 deflected within the first primary angular range 116a to the first optical port 2906a. Similarly, the apparatus 100 may include one or more mirrors disposed on a second side of the optical board 2902 between the optical output of the first positioner 106 and the second optical port 2906b to direct the beam path 114 deflected within the second primary angular range 116b to the second optical port 2906b. An exemplary embodiment of a beam path assembly on the second side of the optical board 2902 is described with respect 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 an AO cell of a first AOD 402 (e.g., as described above), and the second optical component 2004b is provided as an AO cell of a 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, 3012b may be attached to the second side 3000 of the optical board 2902 by any suitable technique described herein or known in the art. However, it will be appreciated that other suitable techniques may be used to provide such optical components on the beam path 114. It will be further understood 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 location between mirror 3006b and second optical component 2004b. In another example, second optical component 2004b may be positioned on beam path 114 at a location 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 FIG. 30 such 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 deflection plane of the first AOD 402, when projected onto the second AOD 404, is different from (e.g. perpendicular to or oblique to) the deflection plane of the second AOD 404. See, for example, International Publication WO 2019 / 060590 A1 for how the deflection plane 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 FIG. 30 such 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 (or at least substantially orthogonal or oblique) to the deflection plane of the second AOD 404. See, for example, International Publication WO 2019 / 060590 A1 for how rotating the deflection plane can be prevented.

[0180] ii. Discussion of Additional Optical Components Although not shown, 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) may be provided within the beam path assembly shown in FIG. 30 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 the beam path 114 (e.g., from the laser source 104 to one or both of the optical ports 2906a and 2906b). The following briefly describes additional optical components that may be incorporated into the beam path assembly shown in FIG. 30. It will be appreciated that the 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 2004a, or from the second optical component 2004b, or a combination thereof. For example, a first beam trap or beam dump system may be disposed at a location between mirror 3006b and second optical component 2004b to selectively trap laser energy propagating from the first optical component 2004a 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 the second optical component 2004b and mirror 3008a to trap laser energy propagating from the second optical component 2004b along a beam path other than the primary beam path 114". In one embodiment, the first beam dump system is provided as an integrated beam dump system 700 and the second beam dump system is provided as an 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 constituting an optical relay system, such as optical relay systems 2000, 2200, 2300, 2400 described above with respect to any of Figures 20, 21, 22, 23, and 24, may include wavefront compensation optics to facilitate compensation of wavefront distortions (e.g., as described above).

[0185] In other embodiments, as exemplarily shown in Fig. 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 necessary, one or more phase retarders may also be disposed on the beam path 114 to rotate the plane of polarization of the laser energy beam incident on the first optical component 2004a (e.g., depending on the wavelength of the laser energy beam and the material forming the first optical component 2004a, 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 first optical component 2004a. In an example embodiment, the first optical component 2004a and the second optical component 2004b are formed from an AO cell material such as crystalline germanium, and the laser energy beam incident on the first optical component 2004a and the 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 the mirrors 3006a and 3006b may be provided as a reflective phase retarder (e.g., configured to provide a 180 degree phase shift). Alternatively, both of the 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 range 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, the apparatus 100 further includes one or more laser sensor systems, such as laser sensor systems 3014a and 3014b. In this embodiment, the 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, the laser sensor system 3014a is positioned to receive the light transmitted through the mirror 3010a, and the laser sensor system 3014b is positioned to receive the light transmitted through the mirror 3010b.

[0187] Generally, each of the 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 the controller 122 where it may be processed to support various functions of the 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 the first positioner 106 for RF power, frequency, etc.), or any combination thereof.

[0188] Because the laser sensor systems 3014a and 3014b are 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 photodetector. As such, movement of the incident laser energy beam on the photodetector 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 spread the laser energy beam before it strikes the photodetector.

[0189] In another embodiment, each of the laser sensor systems 3014a and 3014b may include an integrating sphere 3016 disposed 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 to complement the use of the beam expander / diffuser described above. Generally, as 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 diffuse reflective coating. The integrating sphere 3016 includes a light collection 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 light collection port into the cavity of the corresponding integrating sphere 3016. Light incident on any point on the inner 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 i. Beam Splitting Embodiments As mentioned above, Fig. 4 generally illustrates the deflection of the beam path 114 within a first angular range 116 incident on the multi-axis AOD system 400. To achieve the deflection scheme described above with respect to Fig. 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 Figs. 1, 4, and 31, the first RF drive signal applied to the first AOD 402 to deflect the beam path 114 incident on the multi-axis AOD system 400 within a first first angular range 116a (to the second positioner 108a) may have a first drive frequency f1 within a first frequency range 3102a. 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 a value between these values.

[0192] In general, 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] As shown in Fig. 31, in response to a first applied RF drive signal having a first drive frequency f1 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 f1 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 a first axis of rotation. As will be appreciated, each of the first AOD angular ranges 406a and 406b represents a particular 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 deflects the beam path 114' by an angle within the second AOD angular range 408a by rotating the incident laser energy beam about the second axis of rotation. 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 deflects the beam path 114' by another angle within the second AOD angular range 408b by rotating the incident laser energy beam about the second axis of rotation. As will be appreciated, each of the second AOD angular ranges 408a and 408b represents a particular 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. Further discussion on bias and variance As discussed above, the AOD is a spectrally dispersive element that can distort (e.g., elongate) the process spot that is ultimately impinged on the workpiece 102. The degree to which the process spot is distorted can be characterized, at least in part, as proportional to the spectral linewidth of the laser energy beam and proportional to the deflection caused by the AOD (or 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: Proportional to TIFF2025000607000005.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 made sufficiently low (e.g., so as not to adversely affect the 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 TIFF2025000607000006.tif8170 is the second sub-scan area 3106b TIFF2025000607000007.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. TIFF2025000607000008.tif8170 is the second sub-scan area 3106b TIFF2025000607000009.tif8170, the magnitude of the spectral dispersion imparted to the laser energy beam deflected in 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 in the second sub-scan region 3106b, but the direction of the spectral dispersion is different. Thus, the first dispersion compensator 2600a may have an identical 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 regions In the embodiment shown in FIG. 31, the first frequency ranges 3102a and 3102b are selected in concert with the 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 the sub-scan areas 3106a and 3106b (i.e., the lower right corner of the first sub-scan area 3106a and the upper left corner of the second sub-scan area 3106b as shown in FIG. 31) is 41% larger than either the first frequency range gap or the second frequency range gap. Also, the closest point between the sub-scan areas 3106a and 3106b is actually a point, not a line. Thus, if beam distortion occurs due to beam clipping on a pick-off 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) 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 occurred only at one corner of the sub-scan region, as opposed to 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 made larger or smaller, independently or in concert, as desired, 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-shaped 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 FIG. 31, it will be appreciated that other embodiments are contemplated.

[0201] For example, the arrangement of sub-scan regions 3106a and 3106b may be different than 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 regions, or to generate one or more sub-scan regions having shapes other than a square (e.g., rectangular, circular, oval, triangular, hexagonal, etc.), or to generate sub-scan regions 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 (to the second positioner 108a) within the first primary angular range 116a, 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. 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 to the first AOD 402 within the first frequency range 3300) and driving the second AOD 404 (by applying a second drive frequency to the second AOD 404 within the second frequency range 3104a or the second frequency range 3104b), the resulting scan region of the multi-axis AOD system 400 is effectively divided into multiple sub-scan regions (i.e., the first sub-scan region 3302a and the second sub-scan region 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 FIG.

[0203] Driving the AODs of the multi-axis AOD system 400 with the drive frequency ranges shown in Figure 33 or Figure 34 may be useful, for example, in correcting or at least partially compensating for noticed telecentric 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, within 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 telecentric 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 telecentric errors present along the other 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 split in time a common laser pulse (also referred to herein as a "mother laser pulse") into at least two laser pulses. The time-split 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 split in time into two pulse slices. Specifically, during a first slice period p1, the mother laser pulse 3500 is split into a first pulse slice 3500a, and during a second slice period p2, the mother laser pulse 3500 is split 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 split in time from its 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 successive slice periods may occur consecutively (i.e., one slice period begins immediately after the preceding slice period), or may occur intermittently (i.e., one slice period begins after a delay immediately after the preceding slice period), or a combination thereof. When the successive slice periods occur intermittently, it will be understood that the length of the delay can be characterized as an integer multiple of the positioning period of the first positioner 106 (the integer can 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 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 may be generally 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 some 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 the slicing period, the first positioner 106 may be operated by any method known in the art to attenuate the incident laser energy beam such 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 the slicing period, the first positioner 106 may be operated to deflect the beam path 114 towards a beam trap, 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 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 appropriate.

[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 angle 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 angle 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 3500a and the second pulse slice 3500b to different angles within the first primary angle range 116a (e.g., to deflect the first pulse slice 3500a and the second pulse slice 3500b to the second positioner 108a). 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 FIG. 35A may propagate to the second positioner 108a, and the pulse slice 3500b having the optical power profile shown in FIG. 35B may 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 a positioning error 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] Although FIG. 35 illustrates the laser pulse 3500 being split in time into only two pulse slices (i.e., a first pulse slice 3500a and a second pulse slice 3500b), it will be appreciated that the laser pulse 3500 may be split in time 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, or the like, or any value therebetween). For example, referring to FIG. 36, the laser pulse 3500 may be split in time into four pulse slices 3600a, 3600b, 3600c, and 3600d. In one embodiment, the operation of the first positioner 106 is controlled such that the successively split pulse slices are deflected within different primary angular ranges 116. For example, pulse slice 3600a can be deflected to the first primary angle range 116a, then pulse slice 3600b can be deflected to the second primary angle range 116b, then pulse slice 3600c can be deflected to the first primary angle range 116a, then pulse slice 3600d can be deflected to the second primary angle range 116b. However, in other embodiments, the operation of the first positioner 106 is controlled so that pulse slices that are subsequently divided in sequence are deflected within the same primary angle range 116 or within different primary angle ranges 116. For example, pulse slice 3600a can be deflected to the first primary angle range 116a, then pulse slices 3600b and 3600c can be deflected to the second primary angle range 116b, then pulse slice 3600d can be deflected to the first primary angle 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 the first positioner 106 may be operated to perform pulse slicing on 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 provided as a multi-cell AOD system, pulse slicing may be performed by coordinated operation or actuation of at least two AODs in the multi-cell AOD system. For example, referring to FIG. 37, in embodiments in which the multi-cell AOD system is provided 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 extent 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 extent 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., discussed 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, e.g., 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 the applied RF drive signal may have a non-linear effect on the diffraction efficiency of the AOD, which 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 an 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 an 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 AOD402 is driven by the first RF drive signal, a peak optical power of the laser energy beam deflected during the period when the first AOD402 is driven by the first RF drive signal, an average optical power of the laser energy beam deflected during the period when the first AOD402 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 a second drive frequency of the second RF drive signal, a second frequency range within which the second drive frequency falls, a desired diffraction efficiency when the second AOD 404 is driven by the second RF drive signal, a 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, an 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, or any combination thereof. When operating the AOD system 400 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 a 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 FIG. 3, FIG. 31, FIG. 32, FIG. 33, or FIG. 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 the AOD system 400 is operated to provide beam splitting (e.g., as described above), the first amplitude of the first RF drive signal may be selected such that the optical power of the laser energy beam propagating along the primary beam path 114' deflected within the first AOD angular range 406a 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 406b. 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 406a or 406b. Similarly, the second amplitude of the second RF drive signal may be selected such 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 be varied 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 above is a description of the embodiments and examples of the present invention, and should not be construed as being limiting thereto. Although some 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 significantly 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 some or all of the subject matter of any other sentence, paragraph, example, or embodiment, except where such combinations are mutually exclusive. Thus, the scope of the present invention should be determined by the following claims and the equivalents of such claims to be included therein.

Claims

1. a laser source capable of generating a beam of laser energy propagable along a beam path; a first positioner disposed in the beam path and operable to deflect the beam path; a controller coupled to the first positioner; Equipped with the controller is configured to control operation of the first positioner to deflect the beam path within a first primary angular range and within a second primary angular range, the second primary angular range not overlapping the first angular range and not bordering the first primary angular range; the controller is 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 to a plurality of second angles within a second primary angular range. Laser processing equipment.

2. The apparatus of claim 1 , wherein the laser source is capable of producing a beam of laser energy having a wavelength in the ultraviolet (UV) portion of the electromagnetic spectrum.

3. The apparatus of claim 1 , wherein the laser source is capable of producing a beam of laser energy having a wavelength in the long wavelength infrared (LWIR) portion of the electromagnetic spectrum.

4. The first positioner includes: a first acousto-optic deflector (AOD); and a second AOD optically coupled to the output of the first AOD; Equipped with the first AOD and the second AOD are capable of deflecting the beam path along a same axis; 2. The apparatus of claim 1.

5. a first scan head including a scan lens; a second scan head including a scan lens; at least one optical component positioned to direct the beam path deflected within the first angular range to the first scan head; at least one optical component positioned to direct the beam path deflected within the second angular range to the second scan head; The apparatus of claim 1 , further comprising:

6. 6. The apparatus of claim 5, wherein at least one selected from the group consisting of the first scan head and the second scan head includes a second positioner capable of deflecting the beam path.

7. The apparatus of claim 6 , wherein the second positioner comprises a galvanometer mirror system.

8. A frame, a pick-off mirror coupled to the frame and configured to reflect a beam of laser energy; a beam dump coupled to the frame and configured to absorb the laser energy beam; An integrated beam dump system comprising:

9. The integrated beam dump system of claim 8 , wherein the pick-off mirror is positioned to reflect the laser energy beam to the beam dump.

10. 9. The integrated beam dump system of claim 8, further comprising a relay mirror coupled to the frame and positioned to receive the laser energy beam reflected by the pickoff mirror and reflect the received laser energy beam to the beam dump.

11. The integrated beam dump system of claim 8 , wherein the pick-off mirror includes a coating formed on the frame.

12. a frame having a first surface and at least one second surface; the first surface is configured to reflect a beam of laser energy; the at least one second surface is configured to absorb the laser energy beam. Integrated beam dump system.

13. 13. The integrated beam dump system of claim 12, wherein the first surface is positioned to reflect the laser energy beam to the at least one second surface.

14. 13. The integrated beam dump system of claim 12, wherein the frame has a third surface configured to reflect the laser energy beam, the third surface positioned to receive the laser energy beam reflected by the first surface and reflect the received laser energy beam to the at least one second surface.

15. 13. The integrated beam dump system of claim 12, further comprising a cooling system coupled to the frame, the cooling system being in thermal contact with a portion of the frame having the at least one second surface.

16. The frame is an optical input port; an optical output port disposed adjacent the first surface; Further comprising: the optical input port and the optical output port are disposed on a common axis along which the laser energy beam can propagate.

13. The integrated beam dump system of claim 12.

17. 1. A wavefront correcting optical component 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.

18. 18. The wavefront correcting optical component of claim 17, wherein the ratio of the coefficient of the Z9 term to the coefficient of the Z4 term is in the range of -0.18 to -0.

23.

19. The wavefront correcting optic of claim 17 , wherein the reflective surface is deformable.

20. A deformable mirror is provided, A reflective surface; The main body, a pocket defined within said body; Including, the body includes a shape-changeable membrane region between the reflective surface and the pocket; a central portion of the membrane region having a first thickness and a peripheral portion of the membrane region having a second thickness greater than the first thickness; Wavefront corrected optical components.

21. a base coupled to the body of the deformable mirror, the base having a bore therethrough; the perforation is in fluid communication with the pocket; 21. The wavefront correcting optical component of claim 20.

22. A deformable mirror is provided, A reflective surface; a body including at least one rib; a plurality of pockets defined within said body; Including, the body includes a shape-changeable membrane region between the reflective surface and the pocket; the at least one rib is disposed between the plurality of pockets. Wavefront corrected optical components.

23. 23. The wavefront correcting optical component of claim 22, wherein a central portion of the membrane region has a first thickness and a peripheral portion of the membrane region has a second thickness that is greater than the first thickness.

24. The wavefront correcting optic of claim 22 , wherein the body includes a plurality of ribs.

25. a base coupled to the body of the deformable mirror, the base having at least one perforation therethrough; the at least one perforation is in fluid communication with at least one of the plurality of pockets; 23. The wavefront correcting optic of claim 22.

26. a membrane-type deformable mirror having a pressurizable pocket; a pedestal coupled to the mirror, the pedestal having at least one perforation extending therethrough, the at least one perforation being in fluid communication with the pressurizable pocket; a mount plate coupled to the base and to the optical mount assembly; A wavefront correction optical system comprising:

27. The base is inserted into a hole formed in the mount plate, the at least one bore extends to the hole formed in the mounting plate; 27. The system of claim 26.

28. 30. The system of claim 27, further comprising a fitting inserted into the at least one bore.

29. 30. The system of claim 28, further comprising a hose coupled to an end of the fitting.

30. a first optical component transmissible to the beam of laser energy, the first optical component being susceptible to thermal lensing; a wavefront compensation optic configured to correct wavefront aberrations in the laser energy beam transmitted through the first optical component that are due to the thermal lensing effect; an optical relay system arranged and configured to relay an image of the first optical component at a first plane to a second plane; Equipped with the wavefront compensation optical component is disposed on the second plane; the first optical relay system is configured such that a size of the image of the first optical component at the second plane is different from a size of the image of the first optical component at the first plane. system.

31. 31. The system of claim 30, wherein a size of the image of the first optical component at the second plane is greater than a size of the image of the first optical component at the first plane.

32. 31. The system of claim 30, wherein a size of the image of the first optical component at the second plane is smaller than a size of the image of the first optical component at the first plane.

33. 31. The system of claim 30, wherein the wavefront compensating optic is configured to transmit the laser energy beam.

34. 31. The system of claim 30, wherein the wavefront compensating optic is configured to reflect the laser energy beam.

35. The system of claim 30 , wherein the wavefront compensation optics comprises a static wavefront compensation optic.

36. The system of claim 30 , wherein the wavefront adaptive optics comprises a dynamic wavefront adaptive optic.

37. a second optical component 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 second plane to a third plane; the second optical component is disposed in the third plane.

31. The system of claim 30.

38. 38. The system of claim 37, wherein the optical relay system is configured such that a size of the image of the first optical component at the second plane is the same as a size of the image of the first optical component at the third plane.

39. the wavefront compensating optic is configured to reflect the laser energy beam; The optical relay system includes: a first optical relay including two lenses; a second optical relay including two lenses; Including, 38. The system of claim 37.

40. 40. The system of claim 39, wherein the first optical relay and the second optical relay share a common lens.

41. 40. The system of claim 39, wherein the optical relay system further includes at least one mirror disposed between two lenses of the second optical relay.

42. The system of claim 30 , wherein the first optical component comprises an acousto-optic (AO) cell.

43. 38. The system of claim 37, wherein the second optical component comprises an acousto-optic (AO) cell.

44. 38. The system of claim 37, wherein the first optical component includes an acousto-optic (AO) cell, and the second optical component is positioned such that a zero order beam path of the AO cell of the first optical component is incident on the second optical component.

45. the first optical component includes an acousto-optic (AO) cell capable of transmitting a first laser energy beam along a first order beam path and a second laser energy beam along a zero order beam path; the second optical component is positioned such that the zero-order beam path of the AO cell of the first optical component is incident on the second optical component.

45. The system of claim 44.

46. 46. ​​The system of claim 45, wherein the optical relay system includes a lens disposed on the zero-order beam path of the first optical component, the lens being not a part of the first optical relay or the second optical relay.

47. 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 location optically upstream of the dispersion compensator, the first optical component configured to expand an incident laser energy beam; a second optical component optically coupled to the dispersion compensator and the AOD at a location optically between the dispersion compensator and the AOD, the second optical component configured to demagnify an incident laser energy beam; A system comprising:

48. 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 variably diffracting the incident laser energy beam to deflect the beam path within a first angular range and a second angular range; a first dispersion compensator including at least one selected from the group consisting of a prism and a grating, the first dispersion compensator being optically coupled to an output of the AOD and positioned on the beam path deflected within the first angle range; a second dispersion compensator including at least one selected from the group consisting of a prism and a grating, the second dispersion compensator being optically coupled to an output of the AOD and positioned on the beam path deflected within the second angle range; A system comprising:

49. 50. The system of claim 48, further comprising a first positioner optically coupled to an output of the first dispersion compensator, the first positioner capable of deflecting the diffracted laser energy beam.

50. 50. The system of claim 49, further comprising a second positioner optically coupled to an output of the second dispersion compensator, the second positioner capable of deflecting the diffracted laser energy beam.

51. a laser source capable of generating a beam of laser energy propagable along a beam path; a positioner disposed in 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; 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; A system comprising:

52. 52. The system of claim 51 , wherein the controller is configured to operate the first AOD and the second AOD to temporally divide the laser energy beam into a plurality of pulse slices during a plurality of slice periods, successive slice periods occurring intermittently.

53. 52. The system of claim 51, wherein the controller is configured to operate the first AOD and the second AOD to temporally divide the laser energy beam into pulse slices for different periods of time.

54. 52. The system of claim 51 , wherein the controller is configured to operate at least one selected from the group consisting of the first AOD and the second AOD to temporally divide the laser energy beam into pulse slices for a period of time longer than a slice period.

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