Laser processing apparatus, method for operating the same, and method for processing a workpiece using the same.

Abstract

This relates to laser processing equipment and its components. [Solution] The laser processing apparatus includes a positioner positioned within a beam path through which a laser energy beam can propagate. 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 multiple angles within each of the first and second primary angular ranges. In other embodiments, the integrated beam dump system includes a frame and a pick-off mirror and beam dump connected to the frame. In yet another embodiment, the wavefront correction optical component includes a mirror having a reflective surface having a shape characterized by specific ratios of Fringe-Zernike terms Z4 and Z9. Many more embodiments are disclosed.

Description

Related applications

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

[0002] I.Technical field The embodiments described herein generally relate to laser processing apparatus and its components, and to methods for operating them.

[0003] II.Technical background Generally, laser processing of a workpiece is performed by irradiating the workpiece with laser energy to heat, melt, evaporate, ablate, crack, decolorize, polish, roughen, carbonize, foam, or modify one or more properties or characteristics of one or more materials that make up the workpiece. For example, laser processing can be performed on a workpiece such as a printed circuit board (PCB) to form vias inside it. To process a workpiece at high speed, it may be required to generate laser energy using a high-power laser source, rapidly change the position of the workpiece irradiated with laser energy, and rapidly change the characteristics of the laser energy (e.g., pulse duration, pulse energy, pulse repetition rate). In addition, 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 a specific wavelength range (e.g., wavelengths in the ultraviolet region of the electromagnetic spectrum) may not be suitable for performing the same laser processing using laser energy in other wavelength ranges (e.g., wavelengths in the long-wavelength infrared region of the electromagnetic spectrum). The embodiments described herein were developed in consideration of these problems and other problems discovered by the inventors.

[0004] One embodiment of the present invention can be characterized as a laser processing apparatus comprising a laser source capable of generating a laser energy beam propagating along a beam path, a first positioner positioned 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 the operation of the first positioner to deflect the beam path within a first primary angular range and a second primary angular range. The second primary angular range does not overlap with or touch the first angular range. The controller may be further configured to control the 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 comprising a frame, a pick-off mirror connected to the frame and configured to reflect a laser energy beam, and a beam dump connected to the frame and configured to absorb the laser energy beam.

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

[0007] Another embodiment of the present invention comprises a mirror having a reflective surface, the shape of which is characterized by the Fringe-Zernike terms Z4 and Z9, and the ratio of the coefficient of term Z9 to the coefficient of term Z4 is in the range of -0.1 to -0.3, which can be characterized as a wavefront correcting optical component.

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

[0009] Another embodiment of the present invention can be characterized as a wavefront correcting optical component comprising a shape-variable mirror having a reflective surface, a body including at least one rib, and a plurality of pockets defined within the body. The body may include a shape-variable membrane region between the reflective surface and the pockets. The at least one rib may be positioned between the plurality of pockets.

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

[0011] Another embodiment of the present invention can be characterized as a system comprising: a first optical component capable of transmitting a laser energy beam and susceptible to thermal lensing; a wavefront compensating optical component configured to correct wavefront aberrations in the laser energy beam transmitted through the first optical component, which are caused by the thermal lensing effect; and an optical relay system arranged and configured to relay the image of the first optical component in a first plane to a second plane. The wavefront compensating optical component may be arranged in the second plane. The first optical relay system may be configured such that the size of the image of the first optical component in the second plane is different from the size of the image of the first optical component in the first plane.

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

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

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

[0015] [Figure 1] Figure 1 schematically shows a multi-head laser processing apparatus according to one embodiment. [Figure 2-3] Figures 2 and 3 schematically illustrate a beam path deflection scheme that can be realized using a first positioner according to a certain embodiment. [Figure 4] Figure 4 schematically shows a multi-axis AOD system that can be incorporated into a first positioner according to one embodiment. [Figure 5-6] Figures 5 and 6 schematically show how a beam dump system according to an embodiment can be incorporated into a first positioner. [Figure 7] Figure 7 is a perspective view in an arbitrary u / v / w coordinate system schematically showing an integrated beam dump system according to an embodiment. In Figure 7, the u-axis, v-axis, and w-axis are orthogonal to each other. [Figure 8-9] Figures 8 and 9 are perspective views showing exemplary beam paths through which laser energy can propagate and be trapped within the integrated beam dump system shown in Figure 7. [Figure 10] Figure 10 is a perspective view in an arbitrary u / v / w coordinate system schematically showing an integrated beam dump system according to another embodiment. In Figure 10, the u-axis, v-axis, and w-axis are orthogonal to each other. [Figure 11-14] Figures 11 through 14 are perspective views showing exemplary beam paths through which laser energy can propagate and be trapped within the integrated beam dump system shown in Figure 10. [Figure 15] Figure 15 shows a graph depicting the experimentally determined dependence of the coefficients (and their ratio) of the Z4 and Z9 terms of the fringe Zernike polynomials on the temperature of a bulk transparent material. [Figure 16] Figure 16 schematically shows a plan view of a wavefront compensation optical component according to an embodiment. [Figure 16A] Figure 16A schematically shows a cross-sectional view of the wavefront compensation optical component shown in Figure 16 when cut along line XVIA-XVIA of Figure 16. [Figure 17] Figure 17 schematically shows a cross-sectional view of the wavefront compensation optical component shown in Figure 16 connected to a pedestal according to an embodiment. [Figure 18-19] Figures 18 and 19 schematically show cross-sectional views of wavefront compensation optical components according to other embodiments, each connected to a pedestal. [Figure 20-24] Figures 20, 21, 22, 23, and 24 show an optical relay system according to an embodiment. [Figure 25] FIG. 25 shows an optical mount according to one embodiment. [Figure 26-29] FIGS. 26, 27, 28, and 29 schematically show a beam path assembly incorporating a dispersion compensator according to an embodiment. [Figure 30] FIG. 30 schematically shows a beam path assembly for guiding a beam path from a laser source to a first optical port and a second optical port shown in FIG. 29 according to one embodiment. [Figure 31-34] FIGS. 31, 32, 33, and 34 show graphs illustrating exemplary frequency ranges capable of driving a first AOD and a second AOD of a first positioner according to an embodiment. [Figure 35-41] FIGS. 35, 35A, 35B, 36, 37, 38, 39, 40, and 41 schematically show a technique for performing pulse slicing according to an embodiment. Detailed Description

[0016] Examples of embodiments will be described below with reference to the accompanying drawings. Unless explicitly stated, in the drawings, the sizes, positions, etc. of components, features, elements, etc. and the distances between them are not necessarily to scale and are exaggerated for ease of understanding. The same numbers throughout the drawings mean the same elements. For this reason, even if the same or similar numbers are not mentioned or described in the corresponding drawings, they may be described by referring to other drawings. Also, even elements without reference numbers may be described by referring to other drawings.

[0017] The terms used in this specification are for the sole purpose of describing specific exemplary embodiments and are not intended to be limiting. Unless otherwise specifically defined, all terms used herein (including technical and scientific terms) have the same meaning as generally understood by those skilled in the art. Where used herein, singular nouns are intended to include plural nouns unless the context explicitly indicates otherwise. Furthermore, the terms “equipped with” and / or “equipped with” should be understood to identify the presence of a described feature, integer, step, operation, element, and / or component, but not to exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Unless otherwise specifically indicated, where a range of values ​​is given, that range includes the upper and lower limits, as well as the sub-range between the upper and lower limits of that range. Unless otherwise specifically indicated, terms such as “first” and “second” are used solely to distinguish elements from one another. For example, one node may be called the “first node,” and similarly another node may be called the “second node,” or vice versa.

[0018] Unless otherwise specified, “approximately” or “around” means that quantities, sizes, proportions, parameters, and other quantities and characteristics are not, and do not need to be, exact, and may be approximate, and may be larger or smaller, as needed, or to reflect tolerances, conversion factors, rounding, measurement errors, and other factors known to those skilled in the art. In this specification, spatially relative terms such as “below,” “down,” “below,” “up,” and “above” may be used to facilitate explanation when describing the relationship between one element or feature and another element or feature, as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations in addition to the orientations shown in the figures. For example, an element described as being “below” or “below” another element or feature would, if the object in the figure were inverted, face “above” the other element or feature. Thus, the exemplary term “below” may include both upward and downward orientations. If the object is facing a different direction (for example, if it is rotated 90 degrees or is in a different direction), the spatially relative descriptors used herein may be interpreted accordingly.

[0019] Section headings used herein are for organizational purposes only, unless otherwise specified, and should not be construed as limiting the subject matter discussed. It will be understood that many different forms, embodiments, and combinations are conceivable without departing from the spirit and teachings of this disclosure, and that this disclosure should not be construed as limiting to the examples of embodiments described herein. Rather, these examples and embodiments are provided to fully convey the scope of this disclosure to those skilled in the art, as it is complete and all-encompassing.

[0020] I. Overview The embodiments described herein generally relate to methods and apparatus for laser processing (or more simply, “processing”) a workpiece. Generally, the processing is carried out entirely or partially by irradiating the workpiece with laser radiation to heat, melt, evaporate, ablate, scratch, decolorize, polish, roughen, carbonize, foam, or modify one or more properties or characteristics (e.g., chemical composition, atomic structure, ionic structure, molecular structure, electronic structure, microstructure, nanostructure, density, viscosity, refractive index, permeability, relative permittivity, texture, color, hardness, transmittance to electromagnetic radiation, or any combination thereof) of one or more materials forming the workpiece. The material to be processed may be located outside the workpiece before or during processing, or it may be located entirely inside the workpiece before or during processing (i.e., not outside the workpiece).

[0021] Specific examples of processes that can be performed by the disclosed laser processing apparatus include via drilling or other hole formation, cutting, punching, welding, scribing, engraving, marking (e.g., surface marking, sub-surface marking), laser-induced forward transfer, cleaning, bleaching, high-luminance pixel repair (e.g., color filter darkening, OLED material modification), film removal, surface texturing (e.g., roughening, smoothing), or similar, or any combination thereof. Thus, one or more features that may be formed on or within a workpiece as a result of processing may include openings, slots, vias or other holes, grooves, trenches, scribe lines, grooves, recesses, conductive traces, ohmic contacts, resistance patterns, human-readable or machine-readable marks (e.g., comprising one or more areas within or on a workpiece having one or more distinguishable characteristics visually or tactilely), or similar, or any combination thereof. Features such as openings, slots, vias, and holes may have any preferred or desirable shape in a top view (e.g., circular, elliptical, square, rectangular, triangular, tubular, or similar, or any combination thereof). Furthermore, features such as openings, slots, vias, and holes may extend completely through the workpiece (e.g., to form a so-called "through via" or "through hole") or may extend only partially within the workpiece (e.g., to form a so-called "non-through via" or "non-through hole").

[0022] Workpieces that can be processed can be collectively characterized as being formed from one or more metals, polymers, ceramics, composites, or any combination thereof (for example, whether they are alloys, compounds, mixtures, solutions, composites, etc.). Therefore, the materials that can be processed include one or more metals such as Al, Ag, Au, Cr, Cu, Fe, In, Mg, Mo, Ni, Pt, Sn, Ti, or any combination thereof (whether alloy or composite, for example), conductive metal oxides (e.g., ITO), transparent conductive polymers, ceramics, waxes, resins, interlayer dielectric materials (e.g., low-k dielectric materials such as silicon dioxide, silicon nitride, silicon oxynitride, methylsilsesquioxane (MSQ), hydrogen silsesquioxane (HSQ), tetraethyl orthosilicate fluoride (FTEOS), or any combination thereof), organic dielectric materials (e.g., SILK, benzocyclobutene, Nautilus (all manufactured by Dow), polyfluorotetraethylene (manufactured by DuPont), FLARE (Allied (manufactured by Chemical Co., Ltd.) 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, assembly 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 can 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-type 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, and display substrates (e.g., TFTs, color filters). Examples include substrates on which organic LED (OLED) arrays, quantum dot LED arrays, or any combination thereof are formed, lenses, mirrors, turbine blades, powders, films, foils, plates, molds (e.g., wax molds, molds for injection molding processes and investment casting processes), fabrics (textiles, felt, etc.), surgical instruments, medical implants, packaged products, shoes, bicycles, automobiles, automotive or aerospace parts (e.g., frames, body panels, etc.), appliances (e.g., microwave ovens, ovens, refrigerators, etc.), and device housings (for example, watches, computers, smartphones, tablet computers, wearable electronic devices, or any combination thereof).

[0024] II. System Overview Figure 1 schematically shows a laser processing apparatus according to one embodiment of the present invention.

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

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

[0027] Figure 1 shows a single third positioner 110 that commonly supports multiple workpieces 102, but it can be understood that multiple third positioners 110 may be provided (for example, to support different workpieces 102, or to support a common workpiece 102, or for similar purposes, or for any combination thereof). However, in consideration of the explanation below, it should be understood that including any of the second positioners 108 or third positioners 110 is optional if the function provided by any of the second positioners 108 or third positioners 110 is not required.

[0028] As will be 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 108a. As used herein, the term “beam path” means the path through which the laser energy in the laser energy beam travels as it propagates from the laser source 104 to the scan lens 112. When deflecting the beam path 114 to the second positioner 108a, the beam path 114 can be deflected at any angle within a first angular range (also referred herein as the “first primary angular range 116a”) (for example, this is measured with respect to the beam path 114 incident on the first positioner 106). Similarly, when deflecting the beam path 114 to the second positioner 108b, the beam path 114 can be deflected at any angle within the second angular range (also referred to herein as the "second primary angular range 116b") (for example, this is measured relative to the beam path 114 incident on the first positioner 106). As used herein, the first primary angular range 116a and the second primary angular range 116b are collectively referred to herein as the "primary angular range 116". Generally, the first primary angular range 116a does not overlap with or touch the second primary angular range 116b. The first primary angular range 116a may be greater than, less than, or equal to the second primary angular range 116b. As used herein, deflecting the beam path 114 within one or more primary angular ranges from the primary angular range 116 is referred to as "beam splitting".

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

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

[0031] Figure 1 shows multiple workpieces 102 arranged so that each intersects a different beam axis, but it can be seen that one larger workpiece 102 may be processed by laser energy irradiated from multiple scan lenses. Furthermore, Figure 1 shows multiple scan lenses 112 arranged to transmit laser energy propagating along beam paths deflected by different second positioners 108, but it can be seen that the apparatus 100 may be configured (for example, using mirrors, prisms, beam splitters, or any combination thereof) so that laser energy propagating along beam paths deflected by multiple second positioners 108 passes through a common scan lens 112.

[0032] As used herein, the term “spot size” means the diameter or maximum spatial width of the laser energy beam irradiating a region of the workpiece 102 that is at least partially processed by the irradiated laser energy beam at the point where the beam axes intersect (also called the “process spot,” “spot position,” or simply “spot”). For the purposes of this specification, the spot size is defined as the optical intensity from the beam axis being 1 / e of the optical intensity at the beam axis. 2It is measured as the radial or transverse distance to where it drops down to. Generally, the spot size of a laser energy beam is smallest at the beam waist. When irradiated onto the workpiece 102, the laser energy in the beam can be characterized as hitting the workpiece 102 with a spot size in the range of 2 μm to 200 μm. However, it can be understood that the spot size can be smaller than 2 μm or larger than 200 μm. Thus, a laser energy beam irradiated onto the workpiece 102 can have a spot size greater than, smaller 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 (for example, beam traps, beam expanders, beam shapers, beam splitters, apertures, filters, collimators, lenses, mirrors, prisms, polarizers, phase retarders, diffractive optical elements (commonly known as DOEs in the art), refractive optical elements (commonly known as ROEs in the art), or any combination thereof) for focusing, expanding, collimating, shaping, polarizing, filtering, splitting, combining, cropping, absorbing, or modifying and adjusting the laser energy beam as it propagates along the beam path 114. Optical components such as beam expanders, lenses, beam splitters, prisms, dichroic filters, windows, waveplates, DOEs, and ROEs are collectively referred to herein as “transmissive optical components” insofar as they are composed of a collection of transparent materials (which may be coated with anti-reflective coatings as needed) intended to transmit the incident laser energy beam. As used herein, a collection of positioners and other optical components is considered to constitute a “beam path assembly” when assembled together in the laser processing apparatus 100.

[0034] A. Laser source In one embodiment, the laser source 104 can generate laser pulses. Therefore, the laser source 104 may include a pulsed laser source, a CW laser source, a QCW laser source, a burst-mode laser, or any combination thereof. If the laser source 104 includes a QCW laser source or a CW laser source, the laser source 104 may operate in pulsed mode or in 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 laser source 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 light output by the laser source 104. However, in other embodiments, the laser source 104 may be provided as a QCW laser source or a CW laser source and may not include a pulse gating unit. Thus, the laser source 104 can be broadly characterized as capable of generating a laser energy beam that can be represented as a series of laser pulses that can then propagate along the beam path 114, or as a continuous or quasi-continuous laser beam. Although many embodiments described herein refer to laser pulses, it should be understood that a continuous or quasi-continuous beam can be used as an alternative or additional method where appropriate or necessary.

[0035] The laser energy output by the laser source 104 may have one or more wavelengths in the ultraviolet (UV), visible, or infrared (IR) regions of the electromagnetic spectrum. The laser energy in the UV region of the electromagnetic spectrum may have one or more wavelengths in the range of 10 nm (or around) to 385 nm (or around), such as 100 nm, 121 nm, 124 nm, 157 nm, 200 nm, 334 nm, 337 nm, 351 nm, 380 nm, or wavelengths between any of these values. The laser energy in the visible green region of the electromagnetic spectrum may have one or more wavelengths in the range of 500 nm (or around) to 560 nm (or around), such as 511 nm, 515 nm, 530 nm, 532 nm, 543 nm, 568 nm, or wavelengths between any of these values. The laser energy in the IR region of the electromagnetic spectrum may have one or more wavelengths in the range of 750 nm (or around) to 15 μm (or around), 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, or wavelengths in any of these values.

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

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

[0038] Laser pulses can be output by the laser source 104 at pulse repetition rates in the range of 5 kHz to 5 GHz. However, it can be understood that the pulse repetition rate may be lower than 5 kHz or higher than 5 GHz. Thus, laser pulses can be output by the laser source 104 at pulse repetition rates lower than, higher than, or equal to, values ​​in the range of 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 values ​​in between these values.

[0039] In addition to wavelength, average power, and pulse duration and pulse repetition rate when the laser energy beam is expressed as a series of laser pulses, the laser energy beam irradiated onto the workpiece 102 can be characterized by one or more other properties such as pulse energy and peak power. Such properties include sufficient light intensity (W / cm²) to process the workpiece 102 (for example, to form one or more features). 2 (measured in) and fluence (J / cm²) 2 To irradiate the process spot of the workpiece 102 (as measured by, for example, the wavelength, pulse duration, average power, pulse repetition rate, etc.), it can be selected (based on one or more other characteristics as needed, such as wavelength, pulse duration, average power, pulse repetition rate, etc.).

[0040] Examples of laser types 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, passive 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. Depending on the configuration, a gas laser (e.g., a carbon dioxide laser, 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, SPECTRA Lasers from the ASCEND series, EXCELSIOR series, EXPLORER series, HIPPO series, NAVIGATOR series, QUANTA-RAY series, QUASAR series, SPIRIT series, TALON series, or VGEN series manufactured by PHYSICS, lasers from the PULSTAR series or FIRESTAR series manufactured by SYNRAD, and lasers from the TRUFLOW series manufactured by TRUMPF (for example, TRUFLOWLasers (2000, 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 One or more laser sources include lasers from 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 (including, for example, GPLN-100-M, GPLN-500-QCW, GPLN-500-M, GPLN-500-R, GPLN-2000-S, etc.) manufactured by PHOTONICS, or similar lasers, or any combination thereof.

[0041] B. First positioner Generally, the first positioner 106 is configured to move the beam axis 118 relative to the workpiece 102 along the X-axis (or X direction), Y-axis (or Y direction), or a combination thereof, by deflecting the beam path 114 within, for example, 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) can be understood to mean an axis (or direction) perpendicular 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 (for example, during the first branching period) and to deflect the beam path 114 to the second positioner 108b (for example, during the second branching period after the first branching period), or vice versa, or a combination thereof. In other examples, the operation of the first positioner 106 may be controlled to deflect the beam path 114 to both the second positioner 108a and the second positioner 108b simultaneously. In the embodiments described herein, the length of the first branching period may be longer than, shorter than, or equal to the length of the second branching period. The lengths of the first branching period and the second branching period, respectively, may be longer than, shorter than, or equal to the positioning period of the first positioner 106. In one embodiment, the lengths of the first branching period and the second branching period can be characterized as integer multiples of the positioning period of the first positioner 106 (this integer may be an integer such as 1, 2, 3, 4, 5, 10, 20, 50, 100, or any integer between these values). See the following section for a further explanation of the “positioning period” of the first positioner 106. In one embodiment, the length of each branching period may be 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 longer than, shorter than, or equal to 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 longer than or equal to 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 shorter than the pulse duration of the laser pulse in the laser energy beam. In such embodiments, beam branching can result in the temporal division of the laser pulse. Therefore, this beam branching can also be called "pulse slicing." Pulse slicing, which will be described in more detail below, can be performed in conjunction with beam branching or independently of beam branching. That is, pulse slicing can 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 (for example, within a first primary angular range 116a or a second primary angular range 116b). Thus, pulse slicing can be performed in conjunction with beam branching or independently of beam branching. The period during which a laser pulse is divided in time can be collectively referred to as the "slice period." In this specification, pulse slicing techniques are described as being applied to divide a laser pulse in time, but it will be understood that these techniques can be similarly applied to divide a laser energy beam, which is represented as a continuous or quasi-continuous laser beam, in time.

[0044] The movement of the beam axis relative to the workpiece 102 performed by the first positioner 106 is generally limited so that the process spot can be scanned, moved, or positioned within a first scan area projected by the scan lens 112. Generally, depending on one or more factors such as the configuration of the first positioner 106, the position of the first positioner 106 along the beam path 114, and the beam size of the laser energy beam incident on the first positioner 106, the first scan area may extend to a distance shorter than, longer 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, or any of these values. As used herein, the term “beam size” means the diameter or width of a laser energy beam, where the optical intensity is 1 / e of the optical intensity along the propagation axis along the beam path 114, from the beam axis. 2 It can be measured as a radial or transverse distance down to the point where it drops down. The maximum dimension of the first scan area (for example, in the X or Y direction, or in any other direction) may be greater than, equal to, or less than the corresponding maximum dimension (measured in the XY plane) of a feature (e.g., an opening, a recess, a via, a trench, etc.) formed on the workpiece 102.

[0045] Generally, the first positioner 106 can 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 any combination thereof. The AOD in an AOD system generally includes an AO cell formed from materials such as crystalline germanium (Ge), gallium arsenide (GaAs), chalcite (PbMoO4), tellurium dioxide (TeO2), quartz, glassy SiO2, arsenic trisulfide (As2S3), lithium niobate (LiNbO3), or any combination thereof. The EOD in an EOD system generally includes an EO cell formed from lithium niobate, potassium tantalite niobate, or the like. Insofar as the AO cell and EO cell are configured to transmit the incident laser energy beam, they can be considered a type of transmissive optical component.

[0046] The first positioner 106 can be characterized as having a “first positioning speed,” which means the speed at which the first positioner 106 positions (and thereby moves the beam axis) a process spot to any position within the first scan area. For example, the first positioning speed may 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, or any value between these values. In this specification, this range is also referred to as the first positioning bandwidth. During the operation of the first positioner 106, a drive signal is repeatedly supplied 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 supplied. The rate at which the drive signal is supplied is also called the “update rate” or “refresh rate”. In this specification, the reciprocal of the first positioning rate is called the “first positioning period”, and means the shortest time it takes for the position of a process spot to change from one location in the first scan area to another location in the first scan area. Therefore, the first positioner 106 can be characterized as having a first positioning period that is longer than or less than a value between any of these values, such as 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.

[0047] i. Embodiments relating to AOD systems as a first positioner in general In one embodiment, the first positioner 106 is provided as an AOD system including at least one single-element AOD (e.g., one, two, three, four, five, six, etc.), at least one multi-element AOD (e.g., one, two, three, four, five, six, etc.), or any combination thereof. In this specification, 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 having only one ultrasonic converter element acoustically coupled to an AO cell, and a "multi-element" AOD includes two or more ultrasonic converter elements acoustically coupled to a common AO cell. An AOD system may be provided as a single-axis AOD system (for example, capable of deflecting the beam axis along a single axis) by deflecting the beam path 114 in a corresponding manner, or as a multi-axis AOD system (for example, capable of deflecting the beam axis along one or more axes, e.g., along the X-axis, along the Y-axis, or along any combination thereof). Generally, a multi-axis AOD system may be provided as a single-cell AOD system or a multi-cell AOD system. A multi-cell multi-axis AOD system typically includes multiple AODs, each capable of deflecting the 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 the beam axis along one axis (e.g., along the X-axis) and a second AOD (e.g., a single-element or multi-element AOD) capable of deflecting the 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 the beam axis along two axes (e.g., along the X-axis and Y-axis). For example, a single-cell multi-axis system may include two or more ultrasonic conversion elements acoustically coupled to orthogonally arranged planes, faces, or sides of a common AO cell.

[0048] As will be understood by those skilled in the art, optical optical (AO) technology (e.g., AOD, AOM, etc.) utilizes the diffraction effect caused by one or more sound waves propagating through the AO cell (along the "diffraction axis" of the AOD) to diffract an incident light wave (i.e., a laser energy beam in the context of this application) 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-order and first-order diffraction peaks, and may also include other higher-order (e.g., second-order, third-order, etc.) diffraction peaks. As is known in the art, the portion of the laser energy beam diffracted at the zero-order diffraction peak is called the "zero-order" beam, and the portion of the laser energy beam diffracted at the first-order diffraction peak is called the "first-order" beam, and so on. Generally, the zero-order beam and other-order beams (e.g., the first-order beam) 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 the zero-order beampath, and the primary beam propagates along the primary beampath.

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

number

[0050] The primary beam path exiting the AO cell can typically be considered as a beam path 114 rotated or deflected within the AO cell. Unless otherwise specified herein, the beam path 114 exiting the AO cell corresponds to the primary beam path. The central axis (also referred to herein as the “rotation axis”) around which the beam path 114 exiting the AO cell is rotated (for example, with respect to the beam path 114 when incident on the AO cell) is orthogonal to both the diffraction axis of the AO cell and the optical axis along the direction in 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 otherwise substantially parallel to) the diffraction axis of the AO cell and the optical axis within the AO cell. In this specification, the spatial range in which the AOD can deflect the beam path 114 within the deflection plane is referred to as the “scan region” of the AOD. Therefore, the first scan region of the first positioner 106 can be considered to correspond to the scan region of a single AOD (for example, when the first positioner 106 includes a single AOD), and can be considered to correspond to the combined scan region of multiple AODs (for example, when the first positioner 106 includes multiple AODs).

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

[0052] C. Second position Generally, 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 (for example, by deflecting the beam path 114 within the first secondary angular range 118a or the second secondary angular range 118b).

[0053] The movement of the beam axis relative to the workpiece 102 by the second positioner 108 is generally limited so that the process spot can be scanned, moved, or positioned within a second scan area projected by the scan lens 112. Generally, depending on one or more factors such as the configuration of the second positioner 108, the position 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, the second scan area may extend to a distance longer than the corresponding distance of the first scan area in either the X or Y direction. From the above perspective, the second scan area may extend in either the X or Y direction to a distance shorter than, longer 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, or any of these values. The maximum dimension of the second scan area (for example, in the X or Y direction, or in any other direction) may be greater than, equal to, or less than the maximum dimension (measured in the XY plane) of the features (e.g., openings, recesses, vias, trenches, scribe lines, conductive traces, etc.) formed on the workpiece 102.

[0054] In terms of the configuration 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. Therefore, the second positioner 108 can scan the first scan area within the second scan area.

[0055] Generally, the positioning speed at which the second positioner 108 can position a process spot at any position within the second scan area (thus moving the beam axis within the second scan area and / or scanning the first scan area within the second scan area) is smaller than the range of the first positioning bandwidth (also referred to herein as the "second positioning bandwidth"). In one embodiment, the second positioning bandwidth is in the range of 500 Hz (or around there) to 8 kHz (or around there). For example, the second positioning bandwidth may be higher than, equal to, or lower 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, or any of these values ​​or between them.

[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 both the X-axis and the Y-axis relative to the workpiece 102. In yet another embodiment, the second positioner 108 may be provided as a rotating polyhedron mirror system, etc. Thus, it can be understood that, depending on the specific 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 position The third positioner 110 moves the workpiece 102 (e.g., workpieces 102a and 102b) relative to the scan lens 112, thereby moving the workpiece 102 relative to the beam axis. The movement of the workpiece 102 relative to the beam axis is generally limited to enable scanning, moving, or positioning of process spots within the third scan region. Depending on one or more factors, such as the configuration of the third positioner 110, the third scan region may extend to a distance longer than or equal to the corresponding distance of the second scan region in the X, Y, or any combination thereof. However, generally, the maximum dimension of the third scan region (e.g., in the X, Y, or other directions) is greater than or equal to the corresponding maximum dimension (measured in the XY plane) of the features formed on the workpiece 102. If necessary, the third positioner 110 may be able to move the workpiece 102 relative to the beam axis within a scan area extending in the Z direction (for example, over a range of 1 mm to 50 mm). Thus, the third scan area may extend along the X, Y, and / or Z directions.

[0058] In terms of the configurations described herein, it should be understood that the movement of the process spot on the workpiece 102 (performed, for example, by the first positioner 106 and / or the second positioner 108) can be superimposed on the movement of the workpiece 102 performed by the third positioner 110. For this reason, the third positioner 110 can scan the first scan area and / or the second scan area within the third scan area. Generally, the positioning speed at which the third positioner 110 can position the workpiece 102 at any position within the third scan area (thus moving the workpiece 102, scanning the first scan area within the third scan area, and / or scanning the second scan area within the third scan area) is smaller 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 around that). For example, the third positioning bandwidth may be 500Hz, 250Hz, 150Hz, 100Hz, 75Hz, 50Hz, 25Hz, 10Hz, 7.5Hz, 5Hz, 2.5Hz, 2Hz, 1.5Hz, 1Hz, or equal to or lower than any of these values.

[0059] In one embodiment, the third positioner 110 is provided as one or more linear stages (each capable of providing translational movement to the workpiece 102 along the X, Y, and / or Z directions), one or more rotary stages (each capable of providing rotational movement to the workpiece 102 about axes parallel to the X, Y, and / or Z directions), 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 (making it 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) connected to the stage of a third positioner 110. The fixture may include a support area, within which the workpiece 102 can be mechanically clamped, fixed, held, secured, or supported by the fixture. In one embodiment, the workpiece 102 may be clamped, fixed, held, secured, or supported so as to be in direct contact with a typically flat main support surface of the fixture. In other embodiments, the workpiece 102 may be clamped, fixed, held, secured, or supported so as to be spaced apart from the support surface of the fixture. In one embodiment, the workpiece 102 may be fixed, held, or secured by forces (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 described above, the apparatus 100 may use a so-called "stacked" positioning system as the third positioner 110. This "stacked" positioning system allows the workpiece 102 to move while the positions of components other than the workpiece, such as the first positioner 106, the second positioner 108, and the scan lens 112, are stationary within the apparatus 100 (for example, 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, or any combination thereof, while keeping the workpiece 102 stationary.

[0062] In yet another embodiment, the third positioner 110 may be provided as a so-called “split-axis” positioning system in which one or more components, such as a first positioner 106, a second positioner 108, a scan lens 112, or any combination thereof, are transported by one or more linear or rotary stages (e.g., mounted on a frame or gantry), and the workpiece 102 is transported by one or more other linear or rotary stages. In such an embodiment, the third positioner 110 includes one or more linear or rotary stages that are arranged and operable to move one or more components, such as a scan head (e.g., including a second positioner 108 and a scan lens 112), and one or more linear or rotary stages that are arranged and operable to move the workpiece 102. For example, the third positioner 110 may include a Y-stage that moves the workpiece 102 along the Y-direction and an X-stage that moves the scan head along the X-direction. Examples of split-axis positioning systems that may be usefully or conveniently used in apparatus 100 include any of those disclosed in U.S. Patents No. 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 2014 / 0083983, or any combination thereof. Each of these documents is incorporated herein by reference in its entirety.

[0063] In one embodiment, the third positioner 110 includes a Z-stage, where 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 transported by one or more of the other stages described above for moving or positioning the workpiece 102, or transport one or more of the other stages described above for moving or positioning the workpiece 102, or any combination thereof. In another embodiment, the third positioner 110 includes a Z-stage, where 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 transport the X-stage, or be transported by the X-stage. By moving the workpiece 102 or the scan head along the Z-direction, the spot size on the workpiece 102 can be changed.

[0064] In yet another embodiment, one or more components, such as the first positioner 106, the second positioner 108, and the scan lens 112, may be transported by a multi-axis articulated robot arm (e.g., a 2-axis, 3-axis, 4-axis, 5-axis, or 6-axis arm). In such an embodiment, the second positioner 108 and / or the scan lens 112 may be transported by the end effector of the robot arm, if necessary. In yet another embodiment, the workpiece 102 may be transported directly on the end effector of the multi-axis articulated robot arm (i.e., without the third positioner 110). In yet another embodiment, the third positioner 110 may be transported on the end effector of the multi-axis articulated robot arm.

[0065] D. Scan Lens Generally, the scan lens 112 (for example, provided as either a simple lens or a composite lens) is typically configured to focus a laser energy beam directed along the 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 each other along the beam axis), or any combination thereof. The scan lens 112 may be provided as a non-telecentric lens (as illustrated), a 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 each other along the beam axis), or any combination thereof.

[0066] In one embodiment, the scan lens 112 is provided as a fixed focal length lens and is connected to a movable scan lens positioner (e.g., a lens actuator, not shown) 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 a material such as fused silica, optical glass, zinc selenide, zinc sulfide, germanium, gallium arsenide, or magnesium fluoride. 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 operated (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 on the workpiece 102 can be changed.

[0067] In embodiments where the device 100 includes a lens actuator, the lens actuator may be connected to the scan lens 112 (for example, to allow the scan lens 112 to move relative to the second positioner 108 within the scan head). Alternatively, the lens actuator may be connected to the scan head 120 (for example, to allow the scan head itself to move when the scan lens 112 and the second positioner 108 move together). In other embodiments, the scan lens 112 and the second positioner 108 are integrated into different housings (for example, so that the housing into which the scan lens 112 is integrated is movable relative to the housing into which the second positioner 108 is integrated).

[0068] F. Controller Generally, the device 100 includes one or more controllers, such as a controller 122, for controlling or facilitating the control and operation of the device 100. In one embodiment, the controller 122 is communicatively connected (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 any combination thereof) to one or more components of the device 100, such as a laser source 104, a first positioner 106, a second positioner 108, a third positioner 110, a lens actuator, a scanning lens 112 (if provided as a variable focal length lens), and fixtures, so 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 perform relative movement between the beam axis and the workpiece, and to generate relative motion between the process spot and the workpiece 102 along a path or trajectory (also referred to herein as the “process trajectory”) within the workpiece 102. It will be understood that any two or all three of these positioners may be controlled so 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 three positioners simultaneously generate relative movement between the process spot and the workpiece 102 (thus generating a “composite relative movement” between the beam axis and the workpiece). Of course, it is also possible to control only one positioner (e.g., a first positioner 106, a second positioner 108, or a third positioner 110) to cause a relative movement between the process spot and the workpiece 102 at any given time (thus causing a "non-compound relative movement" between the beam axis and the workpiece).

[0070] In one embodiment, the controller 122 can control the operation of the first positioner 106 to deflect the beam path 114 within each primary angular range 116 in such a way that a composite relative movement or non-composite relative movement occurs between the beam axis and each workpiece 102 (for example, in conjunction with a corresponding second positioner 108, or a third positioner 110, or any combination thereof) to cause a relative movement between the process spot and the workpiece 102 along the 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 by causing a composite relative movement or non-composite relative movement between the beam axis and the workpiece 102a (for example, in conjunction with the corresponding second positioner 108a, or the third positioner 110, or any combination thereof) so as to cause a relative movement 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 causes a composite relative movement or non-composite relative movement between the beam axis and the workpiece 102b (for example, in conjunction with the corresponding second positioner 108b, or the third positioner 110, or any combination thereof) so as to cause a relative movement 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 positioner 106 to deflect the beam path 114 within each primary angular range 116 in a manner that compensates for tracking errors introduced by the corresponding second 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 tracking errors 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 tracking errors introduced by the corresponding second positioner 108b.

[0072] Other examples of operations that can be controlled to perform on one or more of the above-mentioned components include those disclosed in U.S. Patents No. 5,751,585, 5,847,960, 6,606,999, 8,680,430, and 8,847,113, or U.S. Patents No. 4,912,487, 5,633,747, 5,638,267, 5,917,300, and 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, As disclosed in U.S. Patent Publications No. 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, and 9,259,802, or in U.S. Patent Publications No. 2014 / 0026351, 2014 / 0196140, and 2 Examples include operations, functions, processes, and methods disclosed in Patent Nos. 014 / 0263201, 2014 / 0263212, 2014 / 0263223, 2014 / 0312013, or in German Federal Patent No. DE102013201968B4, or in International Patent Publication No. WO2009 / 087392, or any combination thereof. Each of these documents is incorporated herein by reference in its entirety.In other examples, the controller 122 may control the operation of any positioner, including one or more AODs (e.g., in one embodiment, a first positioner 106, a second positioner 108, or a combination thereof), for changing the spot shape or spot size of the laser energy beam irradiated onto the process spot (e.g., by chirpening an RF signal applied to one or more ultrasonic converters of one or more AODs, by applying a spectrally shaped RF signal to one or more ultrasonic converters of one or more AODs, or by similar methods, or by any combination thereof), as disclosed in, for example, International Patent Publication WO2017 / 044646A1. The above publication is incorporated herein by reference in its entirety. The applied RF signal may be chirp linearly or nonlinearly in a desired or preferred manner. For example, the applied RF signal may be chirp at a first speed and then chirp at a second speed 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] Generally, the controller 122 includes one or more processors capable of generating the aforementioned control signals when executing instructions. The processors may be provided as programmable processors capable of executing instructions (e.g., one or more general-purpose computer processors, microprocessors, digital signal processors, or any combination thereof). Instructions executable by the processors may be implemented as software, firmware, or in any preferred form of circuitry, including programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), field-programmable object arrays (FPOAs), application-specific integrated circuits (ASICs) (including digital circuits, analog circuits, and mixed analog / digital circuits), or any combination thereof. Instruction execution may occur on a single processor, distributed across multiple processors, in parallel across multiple processors within a single device or across a network of devices, or in similar manner, or in any combination thereof.

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

[0075] Although not shown in the figures, one or more drivers (e.g., RF drivers, servo drivers, line drivers, power supplies, etc.) may be communicatively coupled to the 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), and the fixture, in order 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), and the fixture, can also be considered to include any suitable drivers known in the art. Each driver typically includes an input to which a controller 122 is communicatively coupled, and the controller 122 is capable of generating one or more control signals (e.g., trigger signals). These control signals may be transmitted to the inputs of one or more drivers associated with one or more components of the device 100. Thus, 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 configured to respond to control signals generated by the controller 122.

[0076] Although not shown, one or more additional controllers (e.g., component-specific controllers) may, as needed, be communicably connected to the inputs of drivers communicably connected 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), and the fixture. In this embodiment, each component-specific controller may be communicably connected to controller 122 and capable of generating one or more control signals (e.g., trigger signals) in response to one or more control signals received from controller 122. These one or more control signals may then be transmitted to the inputs of drivers communicably connected to it. In this embodiment, the component-specific controllers may be operable in the same manner as described with respect to controller 122.

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

[0078] III. Examples of Embodiments relating to the First Positioner A. Embodiments relating to the AOD system Referring to Figure 2, if the first positioner 106 is provided as an AOD system (for example, as described above), the first positioner 106 can be operated to realize a beampath deflection scheme in which the zero-order beampath 200 is located between a first primary angular range 116a and a second primary angular range 116b. In this deflection scheme, the first positioner 106 can be operated or driven to deflect the beampath 114 within the first primary angular range 116a or the second primary angular range 116b by inverting the phase of the applied RF drive signal (for example, in response to an applied RF drive signal having a specific frequency). In the illustrated embodiment, the beam trap 202 is positioned to absorb the laser energy propagating along the beampath 200.

[0079] Referring to Figure 3, if the first positioner 106 is provided as an AOD system (for example, as described above), the first positioner 106 can be operated to realize 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 changing the frequency of the applied RF drive signal without inverting the phase of the applied RF drive signal (for example, in response to an applied RF drive signal having a specific frequency). In the illustrated embodiment, the beam trap 202 is positioned to absorb the 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 (for example, as described above), the AOD may be characterized as a longitudinal-mode AOD or a shear-mode AOD and may be capable of diffracting linearly polarized or circularly polarized laser energy beams. Thus, depending on the wavelength of the laser energy beam and the material forming the AO cells of the AOD in the AOD system, the internal AOD can be directed 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 incident laser energy beam. For example, the wavelength of the laser energy beam may be in the ultraviolet or visible-green region of the electromagnetic spectrum, and the AO cells of the AOD may be formed from a material such as quartz, and the AOD can be directed 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 other examples, if the wavelength of the laser energy beam is in the mid-wavelength infrared or long-wavelength infrared region of the so-called electromagnetic spectrum (i.e., wavelengths ranging from 3 μm (or around) to 15 μm (or around)), and the AOD's AO cell is formed from a material such as crystalline germanium, the AOD can be directed such that the diffraction axis of the AO cell is parallel (or at least substantially parallel) to the polarization plane of the incident laser energy beam.

[0081] With respect to Figure 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. Both the first AOD 402 and the second AOD 404 may be provided in the manner described above. The first AOD 402 is positioned and can be operated to rotate an incident laser energy beam (e.g., propagating along beam path 114) by any angle (e.g., measured with respect to beam path 114 incident on the first AOD 402) within a first angular range (also referred to herein as the "first AOD angular range 406") about a first axis of rotation, thereby transmitting a primary beam propagating along the deflected beam path 114'. Similarly, the second AOD404 is positioned and operated to rotate the incident laser energy beam that has passed through the first AOD402 (which may be a zero-order beam, a primary beam, or any combination thereof) by an arbitrary angle (for example, measured with respect to the beam path 114' incident on the second AOD404) within a second angular range (also referred to in this specification as the "second AOD angular range 408") about a second axis of rotation, thereby transmitting the primary beam propagating along the deflected beam path 114”. To be understood, beam path 114' and beam path 114” each represent specific examples of paths through which the laser energy beam can propagate. Thus, in this specification, beam path 114' and beam path 114” can also be collectively referred to as "beam path 114".

[0082] Generally, the second AOD404 is oriented relative to the first AOD402 such that the second axis of rotation is different from the first axis of rotation. For example, the second axis of rotation may be perpendicular to the first axis of rotation, or it may be oblique to the first axis of rotation. However, in other embodiments, the second AOD404 is oriented relative to the first AOD402 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' such that the deflection plane of the first AOD402 rotates (for example, by 90 degrees or by approximately 90 degrees) with respect to the direction of the deflection plane of the second AOD404 when projected onto the second AOD404. For example, regarding an example of a method for rotating the deflection plane as described above, please refer to International Publication No. WO2019 / 060590A1.

[0083] Generally, the AO cell in the first AOD402 is formed from the same or different material as the AO cell in the second AOD404. Furthermore, the type of sound wave (i.e., shear mode or longitudinal mode) used by the first AOD402 to polarize the incident laser energy beam may be the same as or different from the type of sound wave used by the second AOD404 to polarize the incident laser energy beam.

[0084] It can be understood that the AOD system 400 may be operated at any given time so that only the first AOD 402 generates the primary beam, or only the second AOD 404 generates the primary beam, or both the first AOD 402 and the second AOD 404 generate the primary beam. Therefore, the deflection of the beam path 114 produced by the first positioner 106 can be considered to result from the deflection obtained from beam path 114' alone, or from the deflection obtained from beam path 114'' alone, or from a superposition of the deflections obtained from beam paths 114' and 114''. Similarly, the primary angular range 116 can be considered to be only the first AOD angular range 406, or only 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 Figure 4 may be either the first primary angular range 116a or the second primary angular range 116b shown in either Figure 2 or Figure 3.

[0085] In the embodiment shown in Figure 4, the zero-order beam from the first AOD402 is sent to the second AOD404, and the zero-order beam that passes through the second AOD404 can be absorbed by a beam trap (not shown). However, in other embodiments, the zero-order beam that passes through the first AOD402 may be blocked (for example, by a beam trap or mirror, not shown, placed between the first AOD402 and the second AOD404) to prevent the laser energy propagating from the first AOD402 along the zero-order beam path from being sent to the second AOD404. Blocking the zero-order beam as described above may be preferable if the first AOD402 has a relatively high diffraction efficiency and can be kept on for the entire duration of the laser pulse. However, since the second AOD404 compensates for the first AOD402, the thermal loads on the two AODs are often relatively equal. Therefore, by keeping the first AOD402 on for the entire pulse duration, the average thermal load on both the first AOD402 and the second AOD404 may increase. This increased thermal load on the AODs can potentially lead to undesirable beam distortion (e.g., due to thermal lensing effects).

[0086] Notwithstanding the foregoing, directing a zero-order beam to a second AOD404 may help maintain the AO cell of the second AOD404 at the same temperature (or close to the same temperature) as the AO cell of the first AOD402. Directing a zero-order beam to a second AOD404 may help maintain a relatively uniform temperature distribution within the region of the AO cell of the second AOD404 through which the laser energy beam passes during the operation of the second AOD404. This can eliminate or reduce undesirable effects such as thermal lensing and beam drift during the operation of the second AOD404. From this perspective, directing a zero-order beam to a second AOD404 may be particularly advantageous if the material forming the AO cell has a relatively high absorption coefficient at the wavelength of the deflected laser energy beam. For example, crystalline germanium is known to have a relatively high absorption coefficient in the mid-wavelength infrared to long-wavelength infrared region of the electromagnetic wave spectrum (compared, for example, to the absorption coefficient of quartz in the near-UV to visible wavelength region of the electromagnetic wave spectrum).

[0087] If the first positioner 106 is provided as an AOD system such as AOD system 400, the first positioner 106 may include, as necessary, one or more other additional optical components such as beam traps, beam expanders, beam shapers, apertures, filters, collimators, lenses, mirrors, phase retarders, polarizers, or any combination thereof.

[0088] B. Embodiments relating to beam dump systems in general 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 undesirable beam path. Conventionally, undesirable laser energy propagating from the AOD has its path altered using a pick-off mirror that reflects the laser energy to a beam trap located at a distance (e.g., on its reflective surface). The laser energy may be reflected directly from the pick-off mirror to the beam trap, or it may be reflected indirectly to the beam trap via one or more additional relay mirrors. The pick-off mirror and beam trap (and the relay mirrors between them) constitute a beam dump system.

[0089] Referring to Figure 5, the first positioner 106 may include a beam dump system 500 (also referred to herein as the “first beam dump system”) located on the optical output side of the first AOD402. The first AOD402 typically operates to generate a zero-order beam and a primary beam propagating from the first AOD402 along the zero-order beampath 300 and the primary beampath 114', respectively, by diffracting the incident laser energy beam. In many cases, one or more beams of other diffraction orders are also generated. Each of these beams may propagate from the first AOD402 along one or more other beampaths collectively labeled 502 in Figure 5. The beam dump system 500 is configured to trap the laser energy propagating along any of the beampaths 502, while allowing the laser energy propagating along the zero-order beampath 300 and the primary beampath 114' to propagate (for example, to the second AOD404). In another embodiment, the beam dump system 500 may be configured to trap the laser energy propagating along the zero-order beampath 300 (i.e., to prevent the laser energy from propagating to the second AOD 404).

[0090] Referring to Figure 6, the first positioner 106 may include a beam dump system 600 (also referred to herein as the “second beam dump system”) located on the optical output side of the second AOD404. The second AOD404 typically operates to diffract the incident laser energy beam (for example, propagating from the first AOD402 along the primary beam path 114' and, if necessary, along the zero-order beam path 300 from the first AOD402). During the operation of the second AOD404, the incident laser energy beam propagating along beampath 114' is diffracted to generate a primary beam that propagates from the second AOD404 along primary beampath 114''. Similar to the first AOD402, one or more beams of other diffraction orders may also be generated during the operation of the second AOD404. Each of these beams may propagate from the second AOD404 along one or more other beampaths collectively designated 602 in Figure 6. In addition, at least a portion of the laser energy beam propagating from the first AOD402 along zero-order beampath 300 may propagate from the second AOD404 along zero-order beampath 300. The beam dump system 600 is configured to trap the laser energy propagating along beampaths such as beampaths 300 and 602 while allowing the laser energy propagating along primary beampath 114'' to continue propagating (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 it may include the second beam dump system 600 but not the first beam dump system 500. In this specification, the first beam dump system 500 and the second beam dump system 600 (collectively referred to as the "Beam Dump System" in this specification) are described as being incorporated into a first positioner 106 provided as a multi-cell multi-axis AOD system 400. However, it will be understood that any number of the beam dump systems described herein may be incorporated into a first positioner 106 containing only one AOD, or may be used in conjunction with other optical components such as prisms, lenses, galvanometer mirror systems, fast steering mirror systems, or any combination thereof.

[0092] i. Examples of embodiments relating to beam dump systems In one embodiment, the pick-off mirror and beam trap (and relay mirror between them) of the beam dump system are provided as physically separate components, each separately mounted on a common optical breadboard or the like (e.g., by screws, adhesive, clamps, or any combination thereof). While this provides a flexible solution, positioning these components can be a difficult and time-consuming process.

[0093] To address the aforementioned potential problems associated with separately provided components in a beam dump system, beam dump systems according to other embodiments may integrate (pre-aligned as necessary) pick-off mirrors, beam traps, and intervening relay mirrors into a common package. Such beam dump systems (also referred to herein as “integrated beam dump systems”) can be easily incorporated into beam path assemblies by any preferred method known in the art. In this case, the only alignment required is to align the optical input of the integrated beam dump system with the location of the undesirable beam path.

[0094] In one embodiment, the integrated beam damping system may include one or more separately provided pick-off mirrors, one or more beam traps, and optionally one or more relay mirrors between the pick-off mirrors and beam traps. All of these are attached to a common structure such as an optical breadboard (e.g., by screws, adhesives, clamps, or any combination thereof). As is known in the art, an optical breadboard is a substantially flat structure formed from a material such as steel, brass, aluminum or aluminum alloy, or carbon fiber reinforced polymer composite material, which provides a flat surface to which optical components can be attached (e.g., by screws, adhesives, clamps, or any combination thereof). The optical breadboard is then installed in the beam path assembly of the laser processing apparatus 100.

[0095] In other embodiments, the common structure to which the separately provided components are attached may be a frame (formed from a material such as steel, brass, aluminum or aluminum alloy, copper or copper alloy, or carbon fiber reinforced polymer composite). In this case, the frame has multiple surfaces (at least two of which are not coplanar) to which different components of the separately provided components can be attached (for example, by screws, adhesives, clamps, or any combination thereof). For example, the frame can be manufactured by any preferred or desired method known in the art, such as CNC milling, casting, welding, vacuum bagging, compression molding, or any combination thereof.

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

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

[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 beam trap may be undesirably heated when laser energy is absorbed. Therefore, the integrated beam dump system may include one or more cooling systems that are thermally coupled to the beam trap and configured to remove heat from the beam trap. Examples of suitable cooling systems include heat sinks, heat pipes, Peltier heat pumps, water blocks, or any combination thereof. In one embodiment, one or more cooling systems may be thermally coupled to the optical breadboard or frame. In other embodiments, one or more cooling systems may be integrated with or mechanically coupled to the optical breadboard or frame.

[0099] ii. Examples of embodiments relating to an integrated beam dump system Referring to Figure 7, an integrated beam dump system, such as the 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 any combination thereof. The frame 702 may be formed by any suitable or desired process known in the art (e.g., CNC milling, casting, welding, or any combination thereof) to form multiple surfaces such as surfaces 704, 706, 708, 710, 712, 714, and 716. Generally, surfaces 704, 706, and 708 are provided as reflective surfaces, and surfaces 710, 712, 714, and 716 are provided as absorbing surfaces as needed. For example, as described in detail with respect to Figures 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, and 716 may be arranged relative to each other to form a beam trap 718. In this way, surfaces 704 and 706 can direct the path of laser energy propagating along an undesirable beam path toward surface 708, and surface 708 reflects the diverted laser energy toward the beam trap 718.

[0100] Reflectivity can be made to surfaces 704, 706, and 708 during or after the formation of the frame 702. For example, reflectivity can be made to surfaces 704, 706, and 708 by applying one or more grinding or polishing treatments (for example, as described above) to the region of the frame 702 where one or more of surfaces 704, 706, and 708 are formed after the frame 702 has been formed, or by coating one or more of surfaces 704, 706, and 708 with a suitable reflective material (for example, as described above), or by any combination of these.

[0101] The surfaces 710, 712, 714, and 716 can be made absorbent during or after the formation of the frame 702. For example, the 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 subsequent processes applied to the frame 702 (e.g., one or more etching, roughening, oxidation, anodizing, coating, or any combination thereof) from imparting optical absorbency to surfaces 704, 706, and 708. Examples of masking materials that can be used to mask surfaces 704, 706, and 708 include tapes, waxes, lacquers, and masking resins, as are known in the art. After appropriately masking surfaces 704, 706, and 708, one or more treatments (for example, as described above) may be applied to surfaces 710, 712, 714, and 716 to impart optical absorbency. Subsequently, the mask material may be removed from surfaces 704, 706, and 708, which still retain their reflectivity.

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

[0103] Referring to Figure 8, surface 704 can function as a pick-off mirror, directing the path of laser energy propagating along an undesirable beam path (e.g., beam path 800 propagating from the first AOD 402 or the second AOD 404) towards surface 708. Surface 708 can function as a relay mirror, reflecting the laser energy reflected by surface 704 to a beam trap 718 (e.g., surface 716) where the laser energy is absorbed. Although Figure 8 shows that beam path 800 terminates at surface 716 (suggesting that all laser energy propagating along beam path 800 is absorbed), it can be seen that some laser energy may be reflected at surface 716. In this case, the laser energy is reflected from surface 716 to surface 712, and the remaining energy is either completely absorbed or partially reflected back to surface 716 and at least partially absorbed at surface 716.

[0104] Similarly, referring to Figure 9, surface 706 can function as a pick-off mirror to redirect laser energy propagating to surface 708 along an undesirable beam path (e.g., beam path 900 propagating from the first AOD 402 or the second AOD 404). Surface 708 can function as a relay mirror to reflect the laser energy reflected by surface 704 towards a beam trap 718 where the laser energy is absorbed (e.g., towards surface 710). Figure 9 illustrates that beam path 900 terminates at surface 710 (suggesting that all laser energy propagating along beam path 900 is absorbed), but it can be seen that some laser energy may be reflected at surface 710. In this case, the laser energy is reflected from surface 710 to surface 714, where the remaining laser energy is either completely absorbed or partially reflected back to surface 710 and at least partially absorbed there.

[0105] Returning to Figure 7, frame 702 may further include an aperture 720 that functions as the optical input section of the integrated beam dump system 700. As shown, aperture 720 is positioned and sized to allow laser energy propagating along the beam path from the first AOD 402 or the second AOD 404 (for example, along beam path 114 or 300 as shown in Figure 7, or along other beam paths such as beam path 800 or 900 as shown in Figure 8 or 9, respectively, or along any combination thereof) to pass through it. Frame 702 may further include apertures 722 and 724 that function as the optical output sections of the integrated beam dump system 700. That is, aperture 722 is positioned and sized to allow laser energy propagating along beam path 114 to pass through it. Similarly, aperture 724 is positioned and sized to allow laser energy propagating along beam path 300 to pass through it.

[0106] Referring to Figure 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 aluminum alloy, copper or copper alloy, or any combination thereof. The frame 1002 may be formed by any suitable or desired process known in the art (for example, in the manner described above with respect to frame 702) to form a plurality of surfaces such as surfaces 1004, 1006, 1008, 1010, 1012, 1014, 1016, 1018, and 1020. Generally, surfaces 1004, 1006, 1008, 1010, and 1012 are provided as reflective surfaces, and surfaces 1014, 1016, 1018, and 1020 are provided as light-absorbing surfaces. Any of surfaces 1004, 1006, 1008, 1010, and 1012 may be formed in any way (for example, in the same or similar way as described with respect to surfaces 704, 706, and 708) to suitably reflect the incident laser energy beam. Similarly, any of surfaces 1014, 1016, 1018, and 1020 may be formed in any way (for example, in the same or similar way as described with respect to surfaces 710, 712, 714, and 716) to suitably absorb the incident laser energy beam. Thus, as will be described in more detail with respect to Figures 11 to 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 each other to form a beam trap 1022. In this way, surfaces 1004, 1006, and 1008 can change the path of laser energy propagating along an undesirable beam path. Specifically, surface 1004 is configured to reflect the incident laser energy directly toward the beam trap 1020, while surfaces 1006 and 1008 are configured to reflect the incident laser energy toward surfaces 1010 and 1012, respectively. Surfaces 1010 and 1012 are then configured to reflect the diverted laser energy toward the beam trap 1022, respectively.

[0107] Referring to Figure 11, surface 1004 can function as a pick-off mirror, directing the path of laser energy propagating along an undesirable beam path (e.g., beam path 1100 propagating from the first AOD402 or the second AOD404) towards surface 1014. Although Figure 11 shows that beam path 1100 terminates at surface 1014 (suggesting that all of the laser energy propagating along beam path 1100 is absorbed), it can be seen that some of the laser energy may be reflected at surface 1014. In this case, the laser energy is reflected from surface 1014 to surface 1018, and the remaining laser energy is either completely absorbed at surface 1018 or partially reflected at surface 1014 and at least partially absorbed at surface 1014.

[0108] Similarly, referring to Figure 12, surface 1008 can function as a pick-off mirror, directing the path of laser energy propagating along an undesirable beam path (e.g., beam path 1200 propagating from the first AOD402 or the second AOD404) towards surface 1014. Although Figure 12 shows that beam path 1200 terminates at surface 1016 (suggesting that some of the laser energy propagating along beam path 1200 is reflected at surface 1014, and all of the laser energy propagating along beam path 1200 that is thus reflected is absorbed at surface 1016), it can be understood that some of the laser energy may be reflected at surface 1016. In this case, the laser energy is most likely to be reflected from surface 1016 to surface 1020, and the remaining laser energy is either completely absorbed at surface 1020 or partially reflected at surface 1016 and at least partially absorbed at surface 1016.

[0109] Referring to Figure 13, surface 1006 can function as a pick-off mirror, directing the path of laser energy propagating along an undesirable beam path (e.g., beam path 1300 propagating from the first AOD402 or the second AOD404) toward surface 1010. Surface 1010 can function as a relay mirror, reflecting the laser energy reflected by surface 1004 toward the beam trap 1022 where the laser energy is absorbed (e.g., toward surface 1016). Although Figure 13 shows beam path 1300 terminating at surface 1016 (suggesting that all of the laser energy propagating along beam path 1300 is absorbed), it will be understood that some of the laser energy may be reflected by surface 1016. In this case, the laser energy is reflected from surface 1016 to surface 1020, and the remaining laser energy is either completely absorbed by surface 1020 or partially reflected by surface 1016 and at least partially absorbed by surface 1016.

[0110] Similarly, referring to Figure 14, surface 1008 can function as a pick-off mirror, directing the path of laser energy propagating along an undesirable beam path (e.g., beam path 1400 propagating from the first AOD402 or the second AOD404) toward surface 1012. Surface 1012 can function as a relay mirror, reflecting the laser energy reflected by surface 1008 toward a beam trap 1022 where the laser energy is absorbed (e.g., toward surface 1016). Although Figure 14 shows beam path 1400 terminating at surface 1016 (suggesting that all laser energy propagating along beam path 1400 is absorbed), it will be understood that some laser energy may be reflected by surface 1016. In this case, the laser energy is reflected from surface 1016 to surface 1020, and the remaining laser energy is either completely absorbed by surface 1020 or partially reflected by surface 1016 and at least partially absorbed by surface 1016.

[0111] Returning to Figure 10, frame 1002 may further include an aperture 1024 that functions as the optical input section of the integrated beam dump system 1000. As shown, aperture 1024 is positioned and sized to allow laser energy propagating along the beam path from the first AOD402 or the second AOD404 (for example, along beam path 114 as shown in Figure 10, or along other beam paths such as beam paths 1100, 1200, 1300, 1400 as shown in Figures 11, 12, 13, or 14 respectively, or along any combination thereof) to pass through it. Frame 1002 may further include an aperture 1026 that functions as the optical output section of the integrated beam dump system 1000. That is, aperture 1026 is positioned and sized to allow laser energy propagating along beam path 114 to pass through it. In the integrated beam dump system 1000, the path of the zero-order beam path 300 (propagating, for example, from the first AOD402 or the second AOD404) is directed towards the beam trap 1022 and sent to the beam trap 1022. In this case, the zero-order beam path 300 can be represented, for example, by beam path 1200 or 1300.

[0112] From the above description of the integrated beam dump systems 700 and 1000, it will be understood that the surfaces provided by frames 702 and 1002 define internal regions from which laser energy can propagate toward their respective beam traps. For example, the surface provided by frame 702 defines internal region 726, and the surface provided by frame 1002 defines internal region 1028. To prevent or minimize the entry of undesirable dust or other particles or objects into these internal regions, either the integrated beam dump system 700 or 1000 may optionally include one or more plates extending into the internal regions. For example, the integrated beam dump system 700 may include a first plate 726 connected to the frame 702 (for example, on its first side), a second plate 728 (shown as a dotted line in Figure 7) connected to the frame 702 (for example, on a second side opposite to the first side) (for example, by screws, adhesive, clamps, etc., or any combination thereof), or a combination thereof. Similarly, the integrated beam dump system 1000 may include a first plate 1030 connected to the frame 1002 (for example, on its first side), a second plate 1032 (shown as a dotted line in Figure 10) connected to the frame 1002 (for example, on a second side opposite to the first side) (for example, by screws, adhesive, clamps, etc., or any combination thereof), or a combination thereof. With respect to the integrated beam dump system 1000, although the frame 1002 is described above as providing the surface 1008, the surface 1008 may also be provided by a block (e.g., block 1034) connected to the first plate 1030 (e.g., by screws, adhesives, clamps, or any combination thereof).

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

[0114] C. Embodiments relating to phase retarders in general Depending on the type of AOD included in the first positioner 106, it may be desirable to rotate the plane of polarization (i.e., the plane on which the electric field oscillates) within the primary beam path after passing through the AOD. Rotating the plane of polarization is desirable when the amount of RF drive power required to diffract a substantial portion of the incident laser energy beam into the primary beam largely depends on the polarization state of the deflected laser energy beam. Furthermore, if each AOD in a multi-cell AOD system contains an AO cell made of the same material, and if each AOD in a multi-cell AOD system uses the same type of sound wave to deflect the incident laser energy beam, and if it is preferable to linearize the polarization state in the primary beam that has passed through the first AOD in the multi-cell AOD system (e.g., the first AOD 402 in a multi-axis AOD system 400) and orient it in a specific direction with respect to the diffraction axis of the second AOD in the multi-cell AOD system (e.g., the second AOD 404 in a multi-axis AOD system 400), then it is equally preferable to rotate the polarization state in the primary beam that has passed through the second AOD with respect to the polarization state in the primary beam that has passed through the first AOD, just as the direction of the second AOD is rotated with respect to the direction of the first AOD.

[0115] Examples of phase retarders that can be incorporated into the first positioner 106 include one or more transmission phase retarders (e.g., half-wave plates, quarter-wave plates, eighth-wave plates, etc., or any combination thereof), one or more reflection phase retarders (configured to provide, for example, a 180-degree phase shift, a 90-degree phase shift, etc., or any combination thereof), or any combination thereof. Generally, if necessary, one or more phase retarders can be inserted into the beam path of the laser energy beam incident on the AOD (e.g., the primary beam path or others) to align the polarization plane of the linearly polarized laser energy beam incident on the AOD with the diffraction axis of the AO cell in the AOD. For example, one or more phase retarders may be placed on the beam path 114' between the first AOD and the second AOD to align the polarization plane of the linearly polarized laser energy beam that leaves the first AOD and is incident on the second AOD with the diffraction axis of the AO cell in the second AOD.

[0116] D. Embodiments relating to wavefront distortion compensation in general In many cases, transmissive optical components absorb some of the light incident on them. If the incident light is a high-power laser energy beam, the absorbed light heats the material constituting the transmissive optical component. Sometimes, if the laser energy beam has a non-uniform spatial intensity profile (for example, similar to a Gaussian spatial intensity profile), different regions of the beam heat different parts of the transmissive optical component to different temperatures. For example, the central region of a beam with a Gaussian spatial intensity distribution heats one region of the transmissive optical component more than the peripheral regions of the beam. Since the refractive index of many materials constituting 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 the transmissive optical component. In addition, relatively hot regions of the transmissive optical component may bulge (as a result of thermal expansion), and such expansion can cause the shape of the transmissive optical component to approach that of a lens. Furthermore, changes in the refractive index can occur due to thermally induced mechanical stress within the transmissive optical component (known as the photoelastic effect). In this specification, the heating of different parts of a transmissive optical component in different ways may also be referred to as “differential heating” of the transmissive optical component. Differential heating of a transmissive optical component can be achieved by means other than absorption of laser energy. For example, the transmissive optical component can be placed near a heat source. Transmissive optical components such as EO cells or AO cells may be heated in different ways, for example, when the system in which they are incorporated is in operation. As is known in the art, differential heating of a transmissive optical component can cause a specific change in the refractive index within the transmissive optical component, an effect also known as “thermal lensing.” Thermal lensing can undesirably focus, defocus, or distort the wavefront of the laser energy beam as it propagates along the beam path 114 and passes through the beam path assembly.

[0117] One way to address the potentially harmful effects associated with thermal lensing is to use a transmissive optical component that is substantially transparent to the wavelength of light in the incident laser energy beam (i.e., to prevent thermal lensing). Another approach is to simply reduce the power in the laser energy beam. However, these approaches may be difficult or impossible to implement if a substantially transparent transmissive optical component does not exist, or if a workpiece cannot be processed into the desired shape using a relatively low-power laser energy beam. For this reason, according to embodiments described in more detail below, one or more optical components (hereinafter referred to as "wavefront compensating optics") can be placed in the beam path 114 to compensate (i.e., fully or partially compensate) for wavefront distortion 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 transmission optical component is typically axially symmetric (i.e., round, or at least substantially round), and the distortion caused by the thermal lensing effect is often dependent on one or more phase aberrations, which are also axially symmetric. The phase aberrations occurring on the wavefront of the laser energy beam can be described by combining the Zernike polynomial with coefficients known in the art of appropriate magnitude, namely:

number

[0119] In the discussions herein, the j-th term of the Zernike polynomial is described using the "fringe" (also known as the "University of Arizona") numbering and normalization scheme. Since the following terms are the most notable, they are explicitly shown in Table 1 below. [Table 1] The reader will notice that these terms are rotationally symmetric and, thus, Z j (ρ,θ) does not depend on θ.

[0120] Through experiments conducted by the applicant, when a laser energy beam having a Gaussian spatial intensity profile heats the bulk transparent material of a transmissive optical component and causes a thermal lensing effect within the transmissive optical component, the sign of the coefficient of the Z9 term almost always becomes 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 coefficient of the Z4 term does not change significantly even when the amount of absorbed laser power changes. For this reason, independent arbitrary corrections of the coefficients of the Z4 and Z9 terms are not strictly necessary. These observations depend somewhat on the arbitrary choice of the aperture size that defines the fringe Zernike polynomial fit, but aperture sizes from a value slightly smaller than the 4σ width of the laser energy beam to about twice that value are most useful (for a completely Gaussian beam, the 4σ width is equal to the full width of the beam at the 1 / e 2 off-center point of the intensity at the peak).

[0121] For example, Figure 15 shows a set of experimental graphs illustrating how the coefficients (and their ratios) of the Z4 and Z9 terms change with temperature in a bulk transparent material formed from a block of crystalline germanium (e.g., the type used to form AO cells). In this case, a laser energy beam, generated 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. Since the block was being irradiated with the laser energy beam, the temperature of the germanium block was changed by changing the temperature of the cooling water circulating around the germanium block. In this way, increasing the temperature of the cooling water increased the amount of laser energy absorbed by the germanium. From the graphs shown in Figure 15, it can be seen that the sign of the coefficient of the Z9 term (i.e., the data labeled "a9") is always the opposite of 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. Furthermore, it can 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 significantly. It should be noted that the data in the graph is based on observations when the aperture is approximately 1.6 times the 4σ width of the incident laser energy beam.

[0122] While the above discussion of the thermal lensing effect was specifically based on a combination of a bulk transparent material formed from crystalline germanium and a high-power laser energy beam having a wavelength in the range of 8 μm to 12 μm, it is understandable that the thermal lensing effect can also be observed in other bulk transparent materials used to form AO cells, such as tellurium dioxide, depending on one or more factors (e.g., the presence of impurities in the bulk transparent material, the power of the laser energy beam propagating through the bulk transparent material, the wavelength of the laser energy beam propagating through the bulk transparent material, or any combination thereof). Furthermore, while the above discussion of the thermal lensing effect was specifically based on a bulk transparent material used in AO cells, it is understandable that the thermal lensing effect can also be observed in other transparent optical components formed from bulk transparent materials, such as lenses, beam splitters, prisms, dichroic filters, windows, waveplates, DOEs, ROEs, etc. (which may be coated with one or more anti-reflective coatings as needed), not just other optical components such as laser gain media. Therefore, methods for correcting or compensating for wavefront aberration of a laser energy beam caused by the thermal lensing effect can generally be applied to correct wavefront aberration of a laser energy beam generated by the laser source 104, regardless of which transparent optical component caused the thermal lensing effect.

[0123] i. Examples of embodiments relating to wavefront compensating optical components Having described the properties of aberrations in a laser energy beam that can be caused by the thermal lensing effect, numerous embodiments of wavefront compensating optical components that may be placed in the beam path 114 to compensate for aberrations are described below. However, generally, wavefront compensating optical components can be provided as one or more optical components such as one or more lenses, mirrors, or any combination thereof.

[0124] In one embodiment, the wavefront adaptive optics component has fringe Zernike terms (e.g., Z4, Z9, Z 16A reflective optical component (e.g., a spherical mirror or a curved mirror) having a reflective surface characterized by the following features (or any combination thereof). Here, the coefficients of the Fringe-Zernike term are selected to compensate for wavefront distortion in the laser energy beam. The shape of the reflective surface may be made by any suitable method known in the art (e.g., by high-precision diamond turning of the mirror or by high-precision polishing of the mirror substrate using a magnetorheological fluid method (MRF polishing)).

[0125] In other embodiments, the wavefront adaptive optics component has fringe Zernike terms (e.g., Z4, Z9, Z 16 It may be provided as a transmissive optical component (e.g., a spherical lens) having a reflective surface with a shape characterized by (or any combination thereof). Here, the coefficient of the Fringe-Zernike term is selected to compensate for wavefront distortion in the laser energy beam. In other embodiments, the transmissive optical component may include two or more spherical lenses set at a small distance apart to produce a coefficient of a desired value for the Z9 term.

[0126] In yet another embodiment, the wavefront compensating optical component may be provided as a combination of one or more reflective optical components (for example, provided as described above) and one or more transmissive optical components (for example, provided as described above). In this case, compensation for any amount of the coefficient for the Z4 term can be realized on one or more surfaces of the one or more transmissive optical components, and compensation for any amount of the coefficient for the Z9 term can 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 within the transmissive optical component and can therefore be considered examples of "static wavefront compensating optical components." In other embodiments, wavefront compensating optical components dynamically compensate for the effects caused by thermal lensing within the transmissive optical component and can therefore be considered "dynamic wavefront compensating optical components." In this case, the dynamic wavefront compensating optical component may include one or more variable focal length lenses or lens assemblies, one or more shape-shifting mirrors, and one or more light-transmitting spatial light modulators, either individually or in combination. Examples of shape-shifting mirrors include segmented shape-shifting mirrors (i.e., comprising independently drivable flat-plate mirrors, which may be formed by MEMS technology as needed) and membrane shape-shifting mirrors (i.e., comprising a reflective membrane that can be deformed mechanically, pneumatically, hydraulically, etc., by methods known in the art). Furthermore, the dynamic wavefront compensation optical components may include fixed focal length lenses or lens assemblies that are movable relative to each other, one or more shape-constant mirrors, or any combination thereof (for example, one or more zoom lenses).

[0128] Regardless of the type of optical components within the wavefront compensating optics component, the wavefront compensating optics component may be configured to compensate for (a) wavefront distortion accumulated by the laser energy beam at one or more locations in the “optically upstream” beampath 114 of the wavefront compensating optics component (i.e., before propagation to the wavefront compensating optics component), (b) wavefront distortion expected to accumulate by the laser energy beam at one or more locations in the “optically downstream” beampath 114 of the wavefront compensating optics component (i.e., after propagation from the wavefront compensating optics component), or (c) a combination of (a) and (b). As used herein, wavefront distortion accumulated by the laser energy beam before propagation to the wavefront compensating optics component is also called “actual wavefront distortion,” and wavefront distortion expected to accumulate by the laser energy beam after propagation from the wavefront compensating optics component is also called “expected wavefront distortion.”

[0129] a. Examples of embodiments relating to a membrane-type shape-shifting mirror In one embodiment, referring to Figures 16 and 16A, the membrane-type shape-shifting mirror may be provided as a mirror 1600. Generally, the mirror 1600 includes a reflective surface 1602, a body 1604, and a pocket 1606 formed within the body 1604 (for example, extending from the back surface of the body toward the reflective surface 1602). Thus, the body 1604 can be characterized as including a relatively thin membrane region 1608 (for example, formed between the reflective surface 1602 and the pocket 1606) and a relatively thick membrane region 1610 (for example, surrounding the periphery of the pocket 1606). In one embodiment, the body 1604 may be formed from a material such as copper. The reflective surface 1602 may also be formed from the same material as the body 1604 (for example, 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 by changing the pressure within the pocket 1606. For example, referring to Figure 17, the mirror 1600 may be connected to the base 1700 (e.g., via adhesive, one or more welds, one or more clamps, one or more screws, etc., or any combination thereof) to form a seal extending along the periphery of the pocket 1606 (i.e., at the periphery of the pocket 1606, the peripheral region 1610 of the mirror 1600 is biased against or in close contact with the surface 1702 of the base 1700). The base 1700 includes a perforation 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 sufficiently pressurized (e.g., when the pressure within the pocket 1606 is equal to the ambient pressure of the environment outside the pocket 1606), the reflective surface 1602 is substantially flat. When pocket 1606 is sufficiently pressurized (for example, when the pressure inside pocket 1606 is higher by a predetermined threshold amount than the ambient pressure of the environment outside pocket 1606), the shape of the reflective surface 1602 changes to have at least substantially the same characteristics as the wavefront distortion being compensated for (real wavefront distortion, predicted wavefront distortion, or any combination thereof). The geometric shape of the membrane region 1608 changes as the reflective surface 1602 changes, and the fringe Zernike terms (e.g., Z4, Z9, Z) that can be used to characterize the shape of the reflective surface 1602 are also changed. 16 The coefficients of such factors (or any combination thereof) can be configured to ensure that they change in a way that compensates for wavefront distortion (real wavefront distortion, predicted wavefront distortion, or any combination thereof) in the laser energy beam.

[0131] Generally, the pressure within pocket 1606 can be controlled by one or more control elements, such as a regulator (e.g., a constant pressure regulator or a variable pressure regulator), a control valve (e.g., an electronically controlled control valve that responds to one or more command signals output by controller 122 or other controllers), or any combination thereof. This control element can introduce pressurized air into pocket 1606 (e.g., when laser source 104 is operated to generate a laser energy beam for processing a workpiece) and depressurize pocket 1606 (e.g., when laser source 104 is stopped, or when laser source 104 is operated to generate a low-power beam laser energy to facilitate alignment). In this case, a first end of a hose (e.g., a pneumatic hose, a hydraulic hose) is typically connected to a base 1700 to fluidly communicate with the borehole 1704, and a second end of the hose (opposite the first end) is fluidly communicating with the control element.

[0132] In one embodiment, the device 100 may include a laser power monitor, a wavefront sensor, or any combination thereof, arranged and configured to generate measurement signals representing the power of the laser energy beam (in the case of a laser power monitor), the wavefront (in the case of a wavefront sensor), etc. (for example, at a position optically upstream of the first positioner 106, or at a position optically between the first positioner 106 and the second positioner 108, or at a position optically downstream of the second positioner 108, or a similar position, or any combination thereof) as needed. The measurement signals can be output to the controller 122, or to a component-specific controller associated with the regulator or control valve, or a similar device, 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) then outputs a control signal to the regulator and / or the control valve, and 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, the pressure in pocket 1606 can be increased.

[0133] Returning to Figures 16 and 16A, the geometric shape of the membrane region 1608 may, in one embodiment, be configured to ensure that one or more coefficients of the aforementioned Fringe-Zernike terms 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. Generally, the pressure in the pocket 1606 can vary from 0 psi (or around) to 85 psi (or around). In other embodiments, the geometric shape of the membrane region 1608 may be configured to ensure that the ratio (hereinafter also referred to herein as the “compensation ratio”) between two or more coefficients of the aforementioned Fringe-Zernike terms that can be used to characterize the shape of the reflective surface 1602 is within a predetermined range. For example, the geometric shape of the 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 above range based on the pressure in the pocket 1606, or it may be constant (or at least substantially constant) regardless of the pressure in the pocket 1606.

[0134] From the above viewpoint, the membrane region 1608 may be at least substantially circular when viewed in a plan view (i.e., as shown in Figure 16). The central portion of the membrane region 1608 may have a first thickness t1 that is smaller than the second thickness t2 of the peripheral portion of the membrane region 1608. The membrane region 1608 can be characterized as having a first radius r1, and the aforementioned central portion of the membrane region 1608 (i.e., the portion of the membrane region 1608 having the first thickness t1) can be characterized as having a second radius r2. The first thickness t1 may be in the range of 0.8 mm (or around there) to 0.3 mm (or around there), for example, 0.5 mm (or around there). The second thickness t2 may be in the range of 1.0 mm (or around there) to 2.0 mm (or around there), for example, 1.5 mm (or around there). The first radius r1 may be in the range of 3.0 mm (or around that) to 4.0 mm (or around that), for example, 3.5 mm (or around that). The second thickness r2 may be in the range of 16.0 mm (or around that) to 18.0 mm (or around that), for example, 17.0 mm (or around that). Generally, the mirror 1600 itself can be characterized as having a third radius r3 that is larger than the second radius r2, and the peripheral region 1610 of the mirror 1600 has a third thickness t3 that is much larger than the second thickness t2. For example, the third radius r3 may be in the range of 24 mm (or around that) to 26 mm (or around that) (for example, 25 mm or around that). The third thickness t3 may be in the range of 8 mm (or around that) to 10 mm (or around that) (for example, 10 mm or around that). Figure 16A shows small radii where two different surfaces meet (e.g., radii within the area enclosed by the dotted circle). These radii can reduce stress on the mirror substrate in these areas, thereby reducing the likelihood of crack formation and propagation to these areas. The presence of these radii is expected to extend the lifespan of the mirror 1600 in terms of the number of intermittent pressure cycles that the mirror 1600 can withstand before its shape is permanently altered.

[0135] In one embodiment, the mirror 1600 is formed by obtaining a disc-shaped body (for example, having at least a substantially parallel front and back surface), and then machining the body from the back surface to form a pocket 1606 including 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 methods known in the art (e.g., planar polishing, diamond turning, magnetorheological fluid finishing (MRF), or any combination thereof). If necessary, the polished front surface may be covered with one or more high-reflectivity coatings suitable for reflecting high-power laser energy beams.

[0136] In other embodiments, the mirror 1600 may be formed as described above, but instead of processing the main body to form the first cavity 1612 and the second cavity 1614, only the first cavity 1612 needs to be formed to form the membrane region 1608. Thereafter, one or more stiffeners of any suitable shape, stiffness, thickness, and material may be bonded to the surface of the first cavity 1612 opposite the desired reflective surface 1602. The shape, stiffness, thickness, and material of the stiffeners can be selected so as to ensure that the membrane region 1608 deforms in a manner that compensates for wavefront distortion (actual wavefront distortion, predicted wavefront distortion, or any combination thereof) in the laser energy beam by the method described above. In other embodiments, the mirror 1600 may be formed by attaching a deformable reflective membrane to a cylindrical body.

[0137] As configured as described above, the reflective surface 1602 of the membrane-type shape-deformable mirror 1600 deforms to take on 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, the configuration of the membrane-type shape-deformable mirror 1600 can be modified in any preferred way known in the art such that when the reflective surface 1602 is deformed, 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 Figure 18, a membrane-type shape-shifting mirror may be provided as mirror 1800. Mirror 1800 may be provided in the same manner as described with respect to mirror 1600. However, mirror 1800 may include a number of 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 each other by a pair of annular ribs 1808 and 1810 extending from the back surface of the deformable region 1608. Pockets 1802, 1804, and 1806 (and thus ribs 1808 and 1810) can be formed by any preferred method (for example, by machining the back surface of the body constituting mirror 1800). In other embodiments, pockets 1802, 1804, and 1806 can be formed by first machining a single cavity on the back of the main body constituting the mirror 1800 and then joining the annular ribs 1808 and 1810 to the back of the deformable region 1608.

[0139] When the mirror 1800 is suitably connected to the base 1700 (for example, via adhesive, one or more welds, one or more clamps, one or more screws, or any combination thereof), the peripheral region 1610 as well as the ribs 1808 and 1810 of the mirror 1800 are biased against or in close contact with the surface 1702 of the base 1700. As a result, multiple seals are formed extending along the periphery of the pockets 1802, 1804, and 1806 (in these seals, one or more ribs are biased against or in close contact with the surface 1702, and the peripheral region 1610 is biased against or in close contact with the surface 1702).

[0140] As shown in Figure 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 pocket 1802, the second perforation 1814 (if present) is in fluid communication with pocket 1804, and the third perforation 1816 is in fluid communication with pocket 1806. Pressure control within pockets 1802 and 1806 can be performed 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 illustrated above. If present, the second perforation 1814 is open to the external environment so that pocket 1804 is in fluid communication with the surrounding environment outside 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 depends on the pressure in pocket 1806, or the pressure in pocket 1806 can be controlled in a manner that depends on the pressure in pocket 1802. For example, the first perforation 1812 may be connected to a different control element than the second perforation 1816. In other examples, the first perforation 1812 and the second perforation 1816 are commonly connected to the same control element, which can pressurize or depressurize pocket 1802 relative to pocket 1806, or pressurize or depressurize pocket 1806 relative to pocket 1802, or pressurize or depressurize both pocket 1802 and pocket 1806 in common.

[0141] If pockets 1802 and 1806 are not sufficiently pressurized (for example, if the pressure inside pockets 1802 and 1806 is equal to the ambient pressure of the external environment outside pockets 1802 and 1806), the reflective surface 1602 is substantially flat. If pockets 1802 and 1806 are sufficiently pressurized (for example, if the pressure inside each of pockets 1802 and 1806 is higher by a predetermined threshold amount than the ambient pressure of the environment outside pocket 1804), the portion of the membrane region 1608 exposed by pockets 1802 and 1806 deforms convexly (for example, so as to curve outward away from the surface 1702 of the base 1700), and as a result, the portion of the membrane region 1608 exposed by pocket 1804 deforms concavely (for example, so as to curve inward toward the surface 1702 of the base 1700). In this case, the connection between the membrane region 1608 and the ribs 1808 and 1810 acts as an annular fulcrum, thereby allowing the membrane region 1608 to deform convexly at the positions corresponding to pockets 1802 and 1806, and to deform concavely at the position corresponding to pocket 1804. The geometric shape of the mirror 1800 can be configured to ensure that when 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.

[0142] In other embodiments, referring to Figure 19, the membrane-type shape-shifting mirror may be provided as mirror 1900. Mirror 1900 may be provided in the same manner as described with respect to mirror 1800. However, mirror 1900 includes only a single annular rib 1906 defining a pair of pockets (i.e., pockets 1902 and 1904). Pocket 1904 is annular in shape and extends along the periphery of pocket 1902. Pockets 1902 and 1904 (and thus rib 1906) can be formed by any preferred method (for example, as described with respect to mirror 1800).

[0143] When the mirror 1900 is suitably connected to the base 1700 (for example, via adhesive, one or more welds, one or more clamps, one or more screws, or any combination thereof), the peripheral region 1610 and rib 1906 of the mirror 1900 are biased against or in close contact with the surface 1702 of the base 1700. As a result, multiple seals are formed that extend along the periphery of the pockets 1902 and 1904.

[0144] As shown in Figure 19, the base 1700 includes a first perforation 1908 and a second perforation 1910. The first perforation 1908 is in fluid communication with pocket 1902, and the second perforation 1910 is in fluid communication with pocket 1904. The pressure in 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 illustrated above. In one embodiment, the pressure in pocket 1902 can be controlled independently of the pressure in pocket 1910, or the pressure in pocket 1910 can be controlled independently of the pressure in pocket 1902. In another embodiment, the pressure in pocket 1902 can be controlled in a manner that depends on the pressure in pocket 1904, or the pressure in pocket 1904 can be controlled in a manner that depends on the pressure in pocket 1902. For example, the first perforation 1908 may be connected to a different control element than the second perforation 1910. In other examples, the first perforation 1908 and the second perforation 1910 are connected to the same control element, which can pressurize or depressurize pocket 1902 relative to pocket 1904, or pocket 1904 relative to pocket 1902, or both pocket 1902 and pocket 1904 can be pressurized or depressurized together.

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

[0146] It will be understood that any of the membrane-type shape-shifting mirrors formed and constructed by the methods described above can be modified by any suitable method known in the art so that the shape of the deformed reflective surface 1602 can take on various shapes, not limited to the shape defined by the combination of radially symmetric Fringe-Zernike polynomials described above. For example, the pockets of the membrane-type shape-shifting mirrors described with respect to Figures 16, 18, and 19 are radially symmetric. If the membrane-type shape-shifting mirror is modified to have a non-radially symmetric pocket, the shape of the deformed reflective surface 1602 will not be radially symmetric.

[0147] ii. Embodiments relating to the use of optical relay systems in general Generally, wavefront aberration caused by thermal lensing effects within a transmissive optical component occurs at a specific location within the transmissive optical component, which can be approximated by a plane referred to herein as the “object plane” or “first plane.” Ideally, wavefront aberration is corrected in the object plane (i.e., where the wavefront aberration is generated). However, this is usually physically impossible. Therefore, the object plane is reprojected onto another plane located outside the transmissive optical component (referred to as the “image plane” or “second plane”), and wavefront compensating optical components are positioned in the image plane to compensate for wavefront aberration (e.g., by the method described above).

[0148] Therefore, in one embodiment, the beam path assembly may include an optical relay system located within the beam path 114 to relay or reproject the object plane to the wavefront compensating optical component (i.e., to position the image plane on the wavefront compensating optical component). Generally, An optical relay system may include any number of optical components (e.g., one or more mirrors, one or more lenses, or any combination thereof). The configuration and arrangement of the optical components within the optical relay system may be as known in the art to ensure that the size of the image of an object in the image plane is different from (e.g., larger or smaller than) the actual size of the object in the object plane.

[0149] a. Examples of embodiments relating to optical relay systems Referring to Figure 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. Optical relay system 2000 is incorporated into a beam path assembly that includes a wavefront compensating optics component 2002 and one or both of the first optical component 2004a and the second optical component 2004b. Generally, at least one of the first optical component 2004a and the second optical component 2004b represents an optical component that can distort the wavefront of the incident laser energy beam by thermal lensing (as described above, for example). Therefore, the wavefront compensating optics component 2002 may be configured to compensate for real wavefront distortion accumulated by the laser energy beam as a result of the thermal lensing effect in the first optical component 2004a, or to compensate for expected wavefront distortion accumulated by the laser energy beam as a result of the thermal lensing effect in the second optical component 2004b, or a combination thereof. The wavefront compensating optics component 2002 may be provided as a static wavefront compensating optics component, a dynamic wavefront compensating optics component, or any combination thereof. However, generally, the wavefront compensating optics component 2002 is transparent to the laser energy beam incident upon it and is configured to transmit the incident laser energy beam.

[0150] As illustrated, each of the first optical relay 2000a and the second optical relay 2000b is provided as a pair of lenses. Figure 20 shows that each of the first optical relay 2000a and the second optical relay 2000b does not include any optical components between the lenses, but in other embodiments, one or more optical components (e.g., mirrors) 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 arranged and configured to relay the image of the laser energy beam in the first object plane (i.e., in the plane within the first optical component 2004a) to the first image plane (i.e., the plane located in or within the wavefront compensating optical component 2002) such that the image of the relayed laser energy beam in the first image plane is larger than the image in the first object plane. The second optical relay 2000b is positioned and configured to relay the image of the laser energy beam in the second object plane (i.e., in the plane of the wavefront adaptive optics component 2002 (which may be identical to the first image plane)) to the 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 in the second image plane is smaller than the image in 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 in the second image plane is the same as the size of the image of the laser energy beam in 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 in the second image plane is larger or smaller than the size of the image of the laser energy beam in the first object plane.

[0151] Referring to Figure 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 a wavefront compensating optics component 2100 instead of the wavefront compensating optics component 2002. Similar to the wavefront compensating optics component 2002, the wavefront compensating optics component 2100 may be configured to compensate for real wavefront distortion accumulated by the laser energy beam as a result of the thermal lensing effect in the first optical component 2004a, or to compensate for expected wavefront distortion accumulated by the laser energy beam as a result of the thermal lensing effect in the second optical component 2004b, or a combination thereof. Furthermore, the wavefront compensating optics component 2100 may be provided as a static wavefront compensating optics component, a dynamic wavefront compensating optics component, or any combination thereof. However, in the illustrated embodiment, the wavefront compensating optics component 2100 is configured to reflect the laser energy beam incident on it (in contrast to transmitting the incident laser energy beam). In this embodiment, the wavefront compensating optical component 2100 may be a membrane-type shape-shifting mirror provided by any preferred method (as illustrated above).

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

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

[0154] Figure 22 shows that the first optical relay 2200a and the second optical relay 2200b each do not include any optical components between their lenses, but in other embodiments, one or more optical components (e.g., mirrors) may be interposed between the lenses of one or both of the first optical relay 2200a and the second optical relay 2200b. For example, referring to Figure 23, the optical relay system 2200 described above may be modified (thus constituting the optical relay system 2300) to incorporate a plurality of mirrors (e.g., mirrors 2302 and 2304) arranged along the beam path 114 between the second lens 2204 and the third lens 2206.

[0155] Generally, one or both of the first optical component 2004a and the second optical component 2004b shown in any of Figures 20, 21, 22, 23, and 24 may be provided as one or more of the above-described transmission optical components, a laser gain medium, 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 for any of the above-described AOD systems (for example, consisting of crystalline Ge, GaAs, PbMoO4, TeO2, quartz, glassy SiO2, As2S3, LiNbO3, etc.). For example, the first optical component 2004a may be provided as an AO cell for the first AOD402 described above. The second optical component 2004b may be provided as an AO cell for the second AOD404 described above. Therefore, the first optical component 2004a can be considered as part of the first AOD402, and the second optical component 2004b can be considered as part of the second AOD404. In one specific example, the AO cells of the first AOD402 and the second AOD404 can both be formed from the same material (e.g., Ge, GaAs, PbMoO4, TeO2, quartz, SiO2, As2S3, LiNbO3, etc., or any combination thereof). In such a case, although not shown in the figures, one or more additional optical components, such as a phase retarder, may be provided in the beam path between the first optical component 2004a and the second optical component 2004b (e.g., in the beam path 114 shown in either Figure 22 or Figure 23, or in the beam path 114' shown in Figure 24) (for example, for the purposes described above). For example, one or more phase retarders, such as the phase retarder described above, may be positioned in the beam path between the first optical component 2004a and the first lens 2202, or between the second optical component 2004b and the third lens 2206, or between the first lens 2202 and the third lens 2206, or similar positions, or any combination thereof.

[0156] When the first optical component 2004a and the second optical component 2004b are provided as AO cells for the first AOD402 and the second AOD404 as described above, the beam path 114 propagating from the first optical component 2004a shown in Figure 23 may correspond to the primary beam 114' propagating from the first AOD402 (for example, shown in Figure 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 (for example, shown in Figure 24).

[0157] Referring to Figure 24, in addition to the arrangement and configuration of mirrors 2302 and 2304, the arrangement and configuration of lenses 2202, 2204, and 2206 are such that the magnitude and direction of the angular difference between the primary beam path 114 and the zero-order beam path 300 within 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 section of the first optical component 2004a. This may be useful in facilitating the capture and absorption (i.e., trapping) of laser energy propagating along undesirable beam paths from the second optical component 2004b (for example, using the beam dump system illustrated above).

[0158] As illustrated in Figure 24, the zero-order beam path 300 does not follow the same sequence of optical components as the primary 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 compensating optical component 2100, while the primary beam path 114' propagates through the optical relay system 2300 and is reflected by the wavefront compensating optical component 2100. Therefore, the thermal lensing effect accumulated by the primary beam in the first optical component 2004a (which may include the focusing effect among the distortions as described above) is compensated by the time the primary beam reaches the second optical component 2004b, but the thermal lensing effect accumulated by the zero-order beam in the first optical component 2004a (which may also include the focusing effect) is not compensated 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 becomes significantly smaller than the primary 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 to include a lens 2402 (e.g., a single divergent lens) positioned in the zero-order beam path 300 propagating from the first optical component 2004a to adjust the size of the zero-order beam that ultimately propagates to the second optical component 2004b (thus configuring the optical relay system 2400). In one embodiment, the position and / or orientation of the lens 2402 may be adjustable to shift the position at which the zero-order beam enters the second optical component 2004b.

[0159] In the embodiment described with respect to Figure 24, the zero-order beam path 300 does not follow the same order of optical components as the primary beam path 114', but it will be understood that in other embodiments, the zero-order beam path 300 may follow the same order of optical components as the primary 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, which has left the first optical component 2004a, to the first lens 2202 along a direction at least generally parallel to the primary beam path 114' (for example, the zero-order beam path 300 propagates sequentially through the second lens 2204, toward the wavefront correction optical component 2100, toward the mirror 2302, toward the mirror 2304, through the third lens 2206, toward the second optical component 2004b). In this case, lens 2402 may be omitted from the beam path assembly. In other examples, the size and arrangement of at least one of the first lens 2202, the second lens 2204, the wavefront correcting optical component 2100, the mirrors 2302, 2304, and the third lens 2206 may be adjusted to be located in both the zero-order beampath 300 and the primary beampath 114'.

[0160] E. Embodiments relating to the mounting of optical components Any of the aforementioned optical components, such as lenses, windows, phase retarders, filters, and mirrors, can be held in the appropriate position within the beam path assembly using an optical mount. The optical mount is typically attached to the frame or wall of the apparatus 100, or to an optical breadboard incorporated within the apparatus 100. Often, the mount is configured such that one or more compressive forces act on the optical component to hold and maintain its position under a range of environmental conditions. However, the optical surfaces of some optical components can be very sensitive to mechanical stress, so even relatively small compressive forces can deform the optical surface in an undesirable manner. As used herein, “optical surface” may mean a reflective surface (for example, if the optical component is a mirror) or a refractive surface (for example, if the optical component is a lens).

[0161] One particular type of optical component having an optical surface that is particularly susceptible to undesirable deformation is a membrane-type variable-shape mirror. Thus, in one embodiment illustrated in Figure 25, a mount 2500 for holding a membrane-type variable-shape mirror may include a base such as the pedestal 1700 shown and described with respect to Figure 17, and a mount plate 2502 connected to the pedestal 1700. The mount plate 2502 is connected to the pedestal 1700 by a connecting portion 2504 of the pedestal 1700. In one embodiment, the connecting portion 2504 is threaded, and the mount plate 2502 includes a hole with a female thread configured to screw into the threaded connecting portion 2504. In other embodiments, the connecting portion 2504 is fixed within the hole in the mount plate 2502 by other connecting means (e.g., adhesive, welding, one or more clamps, one or more screws, etc.). The mounting plate 2502 can be connected to any suitable or known fixed or adjustable optical mount assembly (not shown) by any method known in the art (e.g., via one or more screws, clamps, springs, adhesives, etc.). In embodiments in which the connecting portion 2504 is screwed into a threaded hole in the mounting plate 2502, the mount 2500 may also include a lock nut 2506. The lock nut 2506 can be screwed into the threaded hole in the mounting plate 2502 to assist in locking the connecting portion 2504 within the threaded hole in the mounting plate 2502.

[0162] In the illustrated embodiment, the membrane-type variable-shape mirror 1600 is connected to the base 1700 so as not to induce stress (or significant stress) within the membrane region 1608 of the mirror 1600. Furthermore, the perforation 1704 is shown to extend from the surface 1702 along the entire length of the connecting portion 2504, allowing a fluid (e.g., air) to pass through the perforation 1704 to pressurize or depressurize the pocket 1606 in the manner described above. To facilitate the transfer of fluid through the perforation 1704, a fitting 2508 may be inserted at one end of the perforation 1704. The fitting 2508 may be configured to connect to a hose (e.g., to the first end of a hose such as the pneumatic hose, hydraulic hose, etc., described above) by any preferred or known method.

[0163] Figure 25 shows the mount 2500 connected to the base 1700 shown in Figure 17 (for fixing the mirror 1600), but it will be understood that the mount 2500 may be connected to other bases for fixing the mirror 1600 or other membrane-type variable-shape mirrors. For example, the mount 2500 may be connected to the base 1700 shown in Figure 18 (for fixing the mirror 1800), or to the base 1700 shown in Figure 19 (for fixing the mirror 1900). Also, although the mount 2500 is described above as including a base for use in fixing a membrane-type variable-shape mirror, it will be understood that the mount 2500 may include any other suitable base for use in fixing other optical components.

[0164] F. Embodiments relating to chromatic dispersion compensation in general The AOD is a spectrally dispersive element, and as a result, it should be understood 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 can result in a deflected laser energy beam that can be spatially distorted in an undesirable manner (for example, causing an undesirable distortion such as an elongated process spot in the workpiece 102) or a deflected laser energy beam that can be spatially resolved into many beamlets with different wavelengths or spectral linewidths. For this reason, for the laser processing applications described above, it is preferable that the laser energy beam ultimately incident on the AOD in the first positioner 106 has a suitablely narrow spectral linewidth to minimize or eliminate the aforementioned adverse effects of events within the AOD diffraction on a broad-linewidth laser energy beam. The spectral linewidth can be measured, for example, based on the full width at half maximum (FWHM) of the optical power spectral intensity within the laser energy beam.

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

[0166] However, in some embodiments, the spectral linewidth of the laser energy beam ultimately incident on the AOD is not preferably narrow for laser processing applications. For example, a laser energy beam generated by a gas laser lacking a suitable spectrally selectable device (e.g., a high-power or low-power CW or pulsed carbon dioxide or carbon monoxide gas laser) may produce a laser energy beam with 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 will produce a deflected laser energy beam that can be spatially distorted or spatially resolved in the undesirable manner described above. In such embodiments, the beam path assembly may include one or more wavelength dispersion compensators (each also referred to herein simply as "dispersion compensator") positioned in the beam path 114. Generally, dispersion compensators may be provided as prisms, gratings, or any combination thereof. It can be understood that the configuration of the dispersion compensator will vary depending on one or more factors such as the wavelength of the laser energy beam propagating along the beampath 114 and the beam size of the laser energy beam. For example, if the laser energy beam propagating along the beampath 114 has wavelengths in the infrared region of the electromagnetic spectrum (e.g., the MWIR or LWIR region, with wavelengths ranging from 3 μm (or around) to 15 μm (or around)), the dispersion compensator may be provided as a dispersion prism formed from a material such as molten lime, silicon, calcium fluoride, magnesium fluoride, germanium, zinc selenide, zinc sulfide, potassium bromide, sapphire, or sodium chloride.

[0167] i. Examples of embodiments relating to dispersion compensators In one embodiment, referring to Figure 26, the dispersion compensator 2600 is positioned on the beam path 114 at an optically upstream position of the AOD 2602. Generally, the dispersion compensator 2600 must be directed to disperse the laser energy beam on 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 the AOD of the first positioner 106 (e.g., the first AOD 402 or the second AOD 404).

[0168] In other embodiments, referring to Figure 27, the dispersion compensator 2600 is positioned optically upstream of the AOD 2602 and between components of an optical relay system on the beampath 114. For example, the optical relay system may include a first beam expander 2700 positioned optically upstream of the dispersion compensator 2600 and a second beam expander 2702 positioned 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 beampath 114 (for example, 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 from the dispersion compensator 2600 along the beampath 114 (for example, from a second beam size or around it to a first beam size, or to a third beam size). The third beam size may be smaller than the second beam size, and may be smaller or larger than the first beam size. Similar to the embodiment shown in Figure 26, the AOD2602 shown in Figure 27 is the AOD of the first positioner 106 (e.g., the first AOD402 or the second AOD404). If the beam size expansion provided by the first beam expander 2700 is sufficiently large, the design specifications of the dispersion compensator 2600 can be advantageously relaxed (which generally reduces the cost of manufacturing the dispersion compensator 2600).

[0169] In some cases, the primary laser energy beam diverges as it propagates along the beam path 114'. Therefore, 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 AOD2602 (e.g., when AOD2602 is the first AOD402 described above). In such cases, referring to Figure 28, a dispersion compensator 2600 can be placed on the beam path 114 at a position optically downstream of AOD2602. In the embodiment shown in Figure 28, AOD2602 is the second AOD404 of the first positioner 106. Therefore, the beam path 114 corresponds to the primary beam path 114''. Thus, the illustrated distance "d" (also referred to herein as "path length") represents the length along the beam path 114 (e.g., primary beam path 114'') between the optical output section of the second AOD404 and the optical input section of the second beam positioner 108 (e.g., the second positioner 108a or the second positioner 108b). Generally, the distance "d" can range from 1 m (or around that) to 5 m (or around that). However, it can be understood that the distance "d" may be shorter if, for example, one or more defocus elements (e.g., one or more suitable lenses, mirrors, etc.) are inserted into the 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), but it will be understood that other types of dispersion compensators, such as other suitable prism geometric shapes (e.g., equilateral triangular prisms) or gratings, can be used.

[0171] In embodiments where the apparatus 100 includes a plurality of second positioners 108 (for example, second positioners 108a and 108b as described above with reference to Figure 1), the beam path assembly of the apparatus 100 may include a plurality of dispersion compensators 2600 accordingly. For example, referring to Figure 29, the beam path assembly may include a first dispersion compensator 2600a and a second dispersion compensator 2600b. The first dispersion compensator 2600a is positioned on a beam path 114 deflected within a first primary angular range 116a, and the second dispersion compensator 2600b is positioned on a beam path 114 deflected within a second primary angular range 116b. In embodiments where the beam path 114 is a beam path deflected by a first positioner 106 (as described above with reference to Figure 4), the beam path 114 corresponds to the primary beam path 114” described above.

[0172] In the embodiment shown in Figure 29, the first dispersion compensator 2600a and the second dispersion compensator 2600b are each mounted on the optical wall 2902 (for example, on its first side surface 2904). Similarly, the second positioners 108a and 108b may, but are not required to, be mounted on the first side surface 2904 of the optical wall 2902. The beam path 114 deflected by the first positioner 106 can 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 formed in the optical wall 2902 (i.e., the first optical port 2906a) and then guided to the first dispersion compensator 2600a (after being reflected by a set of first mirrors, such as mirrors 2908a1, 2908a2, 2908a3, each collectively referred to as the "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 formed in the optical wall 2902 (i.e., the second optical port 2906b) and then guided to the second dispersion compensator 2600b (after being reflected by a set of second mirrors, such as mirrors 2908b1, 2908b2, 2908b3, each collectively referred to as the "second mirror 2908b"). The beam path 114 exiting the first dispersion compensator 2600a is led to the second positioner 108a (after being reflected, for example, by the mirror 2910a). Similarly, the beam path 114 exiting the second dispersion compensator 2600b is led to the second positioner 108b (after being reflected, for example, by the mirror 2910b).

[0173] In the embodiment shown in Figure 29, each of the mirrors 2908a, 2908b, 2910a, and 2910b is mounted on 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 by other preferred methods. Furthermore, it will be understood that the beam path assembly shown in Figure 29 may be provided in different forms (for example, by different arrangements of the mirrors 2908a, 2908b, 2910a, and 2910b, by different arrangements of the second positioner 108, by increasing or decreasing the number of mirrors from those shown, or in similar forms, or by any combination thereof). In one embodiment, the orientation of the first dispersion compensator 2600a (for example, with respect to the first mirror 2908a3) is different from the orientation of the second dispersion compensator 2600a (for example, with respect to the first mirror 2908b3), resulting in a difference in dispersion introduced into the primary laser energy beam when the first positioner 106 is operated to deflect the beam path 114 within a second primary angular range 116b compared to when the first positioner 106 is operated to deflect the beam path 114 within a first primary angular range 116a.

[0174] G. Additional embodiments relating to beam path assemblies Although not shown in Figure 29, the apparatus 100 may include one or more mirrors positioned on the second side of the optical board 2902 (opposite to the first side 2904) between the optical output of the first positioner 106 and the first optical port 2906a, for guiding the beam path 114, deflected within a first primary angular range 116a, to the first optical port 2906a. Similarly, the apparatus 100 may include one or more mirrors positioned on the second side of the optical board 2902 between the optical output of the first positioner 106 and the second optical port 2906b, for guiding the beam path 114, deflected within a second primary angular range 116b, to the second optical port 2906b. An exemplary embodiment relating to the beam path assembly on the second side of the optical board 2902 is described with reference to Figure 30.

[0175] Referring to Figure 30, the second side of the optical board 2902 is identified as 3000. The first optical port 2906a, the second optical port 2906b, the first optical component 2004a, the second optical component 2004b, and the aforementioned laser source 104 are also illustrated. In the embodiment shown in Figure 30, the first optical component 2004a is provided as the AO cell of the first AOD402 (e.g., described above), and the second optical component 2004b is provided as the AO cell of the second AOD404 (e.g., described above). Thus, the first optical component 2004a can be considered as part of the first AOD402, and the second optical component 2004b can be considered as part of the second AOD404.

[0176] As illustrated in Figure 30, multiple mirrors may be provided to facilitate the guidance of 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 guide 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 guide the beam path 114 from the first optical component 2004a to the second optical component 2004b, a third set of mirrors 3008a, 3010a, and 3012a may be provided to guide 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, and 3012b may be provided to guide 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 Figure 30, mirror 3008a may be provided as a pick-off mirror.

[0177] Optical components such as the first optical component 2004a, the 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 preferred method described herein or known in the art. However, it will be understood that such optical components may be provided on the beam path 114 by other preferred methods. Furthermore, it will be understood that the beam path assembly shown in Figure 30 may be provided in different forms (for example, by different arrangements of mirrors 3004a, 3004b, 3006a, 3006b, 3008a, 3008b, 3010a, 3010b, 3012a, 3012b, by different arrangements of optical components 2004a and 2004b, by increasing or decreasing the number of mirrors from that shown, or in similar forms, or by any combination thereof). For example, the first optical component 2004a may be positioned on the beam path 114 between mirror 3006b and the second optical component 2004b. In another example, the second optical component 2004b may be positioned on the beam path 114 between the first optical component 2004a and mirror 3006a.

[0178] i. Discussion regarding the first and second optical components In one embodiment, the first optical component 2004a is oriented relative to the second optical component 2004b in the beam path assembly shown in Figure 30 such that the second rotation axis associated with the second AOD404 incorporating the second optical component 2004b is parallel (or at least substantially parallel) to the first rotation axis associated with the first AOD402 incorporating the first optical component 2004a. In this case, the mirrors 3006a and 3006b are oriented to ensure that when the deflection plane of the first AOD402 is projected onto the second AOD404, it is different from (e.g., perpendicular to or oblique to) the deflection plane of the second AOD404. For example, see International Publication WO2019 / 060590A1 for how the deflection plane can rotate.

[0179] In other embodiments, the first optical component 2004a is oriented relative to the second optical component 2004b in the beam path assembly shown in Figure 30 such that the second rotation axis associated with the second AOD404 incorporating the second optical component 2004b is perpendicular (or at least substantially perpendicular or obliquely intersecting) the first rotation axis associated with the first AOD402 incorporating the first optical component 2004a. In this case, the mirrors 3006a and 3006b are oriented to ensure that when the deflection plane of the first AOD402 is projected onto the second AOD404, they remain perpendicular (or at least substantially perpendicular or obliquely intersecting) with the deflection plane of the second AOD404. For example, see International Publication WO2019 / 060590A1 for how rotation of the deflection plane can be prevented.

[0180] ii. Discussion regarding additional optical components Although not shown in the illustration, the beam path assembly shown in Figure 30 may include one or more other optical components (e.g., beam traps, beam dump systems, beam expanders, beam shapers, beam splitters, apertures, filters, collimators, lenses, mirrors, prisms, polarizers, phase retarders, DOEs, ROEs, or any combination thereof) for focusing, expanding, collimating, shaping, polarizing, filtering, splitting, combining, cropping, absorbing, modifying, adjusting, or directing 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 Figure 30. It will be understood that the beam path assembly may include one or more of these optical components in any combination.

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

[0182] In other embodiments, one or more beam traps or beam dump systems may be provided to capture or absorb laser energy propagating from the first optical component 2004a, the second optical component 2004b, or a combination thereof along undesirable beam paths. For example, a first beam trap or beam dump system may be positioned between the mirror 3006b and the second optical component 2004b to selectively trap laser energy propagating from the first optical component 2004a along all beam paths except the primary 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 the mirror 3008a to trap laser energy propagating from the second optical component 2004b along beam paths 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 compensating optical components such as wavefront compensating optical components 2002 or 2100, or any combination thereof, may be provided to compensate for real wavefront distortion or predicted wavefront distortion (for example, as described above) (for example, they may be located on the beam path 114 between the first optical component 2004a and the second optical component 2004b, i.e., on the beam path 114').

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

[0185] In other embodiments, as illustrated in Figure 30, one or more phase retarders (e.g., as described above) may be placed on the beam path 114 to rotate the polarization plane 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 polarization plane 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 similarly be placed on the beam path 114 to rotate the polarization plane 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 deflection plane of the laser energy beam is parallel or perpendicular (or at least substantially parallel or perpendicular) to the diffraction axis of the first optical component 2004a. In one embodiment, the first optical element 2004a and the second optical element 2004b are formed from an AO cell material such as crystalline germanium, and the laser energy beam incident on the first optical element 2004a and the second optical element 2004b is characterized by having a wavelength in the range of 9 μm (or around) to 11 μm (or around) and an average power in the range of 20 W (or around) to 20 kW (or around). In such an embodiment, one of the mirrors 3006a and 3006b may be provided as a reflection phase retarder (configured to give, for example, a 180-degree phase shift). Alternatively, both mirrors 3006a and 3006b may be provided as reflection phase retarders (configured to give, for example, 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., UV or visible regions of the electromagnetic spectrum) and power characteristics (e.g., average power, peak power, etc.) sufficient to process the workpiece (e.g., as described above).

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

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

[0188] Since the laser sensor systems 3014a and 3014b are located optically downstream of the first optical component 2004a and the second optical component 2004b, which are AODs of the first positioner 106, respectively, the readings from the photodetector may vary depending on the position and angle of the energy beam incident on the photodetector. As a result, reading errors may occur as the incident laser energy beam moves across the photodetector, which may lead to incorrect power control or system calibration. To reduce or eliminate the spatial and directional hypersensitivity associated with the photodetector, each of the laser sensor systems may include a beam expander and / or diffuser positioned to expand and / or diffuse the laser energy beam before it strikes the photodetector.

[0189] In other embodiments, each of the laser sensor systems 3014a and 3014b may include an integrating sphere 3016 positioned optically upstream of the photodetector to reduce spatial and directional hypersensitivity 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 is known in the art, the integrating sphere 3016 is an optical component comprising a hollow spherical (or at least substantially spherical) cavity whose inner surface is coated with a diffuse reflection coating. The integrating sphere 3016 includes a light-gathering port (illustrated but not referenced) and a detection port. The integrating sphere 3016 is positioned so that light propagating from a partially transparent mirror (i.e., from mirror 3010a or 3010b) can enter the corresponding cavity of the integrating sphere 3016 through the light-gathering port. Light incident on any point on the inner surface of the cavity is scattered and eventually exits the integrating sphere 3016 at the detection port and enters a photodetector (specified as 3018 in this embodiment).

[0190] Embodiments relating to the H.AOD driving method i. Embodiments relating to beam splitting As described above, Figure 4 generally illustrates the deflection of the beam path 114 within the primary angular range 116 incident on the multi-axis AOD system 400. With respect to Figure 3, in order to realize the deflection scheme described above, the AOD 402 can 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 can be operated or driven by a second applied RF drive signal having a drive frequency within one of a plurality of second frequency ranges. For example, referring to Figures 1, 4, and 31, in order to deflect the beam path 114 incident on the multi-axis AOD system 400 within the first primary angular range 116a (to the second positioner 108a), the first RF drive signal applied to the first AOD 402 may have a first drive frequency f1 within the first frequency range 3102a. A second RF drive signal applied to the second AOD 404 may have a second drive frequency f2 within the corresponding second frequency range 3104a. A 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 second primary angle range 116b (to the second positioner 108b) may have a first drive frequency f1 within the first frequency range 3102b. A second RF drive signal applied to the second AOD 404 may have a second drive frequency f2 within the corresponding second frequency range 3104b.

[0191] Generally, the first frequency range 3102a does not overlap with the first frequency range 3102b, nor is it adjacent to the first frequency range 3102b. Similarly, the second frequency range 3104a does not overlap with the second frequency range 3104b, nor is it adjacent to the second frequency range 3104b. Therefore, 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. Generally, the gap between the first frequency range 3102a and the first frequency range 3102b (i.e., the “first frequency range gap”) may be greater than, less than, or equal to the gap between the second frequency range 3104a and the second frequency range 3104b (i.e., the “second frequency range gap”). Both the first and second frequency range gaps may have values ​​such as 0.3 MHz, 0.5 MHz, 0.7 MHz, 0.9 MHz, 1 MHz, 2 MHz, 5 MHz, 10 MHz, or a range between these values.

[0192] Generally, the first frequency range 3102a, the first frequency range 3102b, the second frequency range 3104a, and the second frequency range 3104b span a range of frequencies. For example, any of the frequency ranges 3102a, 3102b, 3104a, and 3104b may be equal to 3MHz, 5MHz, 7MHz, 9MHz, 10MHz, 12MHz, 15MHz, 20MHz, or values ​​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 Figure 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 the first AOD angular range 406a by rotating the incident laser energy beam around a first rotation axis. 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 the first AOD angular range 406b by rotating the incident laser energy beam around a first rotation axis. As can be understood, the first AOD angular ranges 406a and 406b each represent specific embodiments of the “first AOD angular range 406” described above, and for this reason, they can 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 around the second rotation axis. 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 around the second rotation axis. As can be understood, each of the second AOD angular ranges 408a and 408b represents a specific embodiment of the “second AOD angular range 408” described above, and for this reason, they can be collectively referred to as the “second AOD angular range 408”.

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

[0196] a. Additional discussion on bias and variance As described above, AODs are spectral dispersion elements capable of distorting (e.g., elongating) the process spot ultimately irradiated onto the workpiece 102. The degree of process spot distortion can be characterized, at least partially, as being 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 produced by multiple AODs). For example, the spectral dispersion resulting from the sum of the deflections of the first AOD 402 and the second AOD 404 is, if f1 is the first drive frequency and f2 is the second drive frequency, It is proportional to TIFF2026086632000005.tif8170.

[0197] While a dispersion compensator 2600, such as a prism, can compensate for the spectral dispersion described above, a given prism combined with a given beam size can only compensate for a fixed amount of spectral dispersion. Therefore, the operation of driving the AOD to deflect the laser energy beam can still impart some distortion to the process spot in the workpiece 102. The amount of strain applied to the process spot in the workpiece 102 can be made sufficiently low (for example, so as not to adversely affect the processing of the workpiece 102) by orienting the first dispersion compensator 2600a to optimally compensate for spectral dispersion resulting from deflection at or near the center of the first subscan region 3106a (for example, relative to the first mirror 2908a3), and by orienting the second dispersion compensator 2600b to optimally compensate for spectral dispersion resulting from deflection at or near the center of the second subscan region 3106b (for example, relative to the first mirror 2908b3), while balancing the sizes of the first subscan region 3106a and the second subscan 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 subscan region 3106a and the second subscan region 3106b are, relative to the first subscan region 3106a. TIFF2026086632000006.tif8170 is for the second subscan region 3106b It may be selected to be equal to (or at least substantially equal to) TIFF2026086632000007.tif8170. f1 for the first subscan region 3106a may be equal to (or at least substantially equal to) f2 for the second subscan region 3106b. Similarly, f2 for the first subscan region 3106a may be equal to (or at least substantially equal to) f1 for the second subscan region 3106b. TIFF2026086632000008.tif8170 is for the second subscan region 3106b If the result is equal to (or at least substantially equal to) TIFF2026086632000009.tif8170, then the magnitude of spectral dispersion imparted to the laser energy beam deflected in the first subscan region 3106a is equal to (or at least substantially equal to) the magnitude of spectral dispersion imparted to the laser energy beam deflected in the second subscan region 3106b, but the direction of spectral dispersion is different. For this reason, the first dispersion compensator 2600a may have the same configuration as the second dispersion compensator 2600b, but the direction of the first dispersion compensator 2600a (for example, with respect to the first mirror 2908a3) is different from the direction of the second dispersion compensator 2600b (for example, with respect to the first mirror 2908b3). That is, the direction of the first dispersion compensator 2600a (for example, relative to the first mirror 2908a3) may correspond to the direction of spectral dispersion given to the laser energy beam deflected at or near the center of the first subscan region 3106a. The direction of the second dispersion compensator 2600b (for example, relative to the first mirror 2908b3) may correspond to the direction of spectral dispersion given to the laser energy beam deflected at or near the center of the second subscan region 3106b.

[0199] b. Additional discussion regarding subscan regions In the embodiment shown in Figure 31, the first frequency ranges 3102a and 3102b are selected in coordination with the second frequency ranges 3104a and 3104b to generate a pair of square subscan regions 3106a and 3106b that are spatially offset from each other 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 subscan regions 3106a and 3106b (i.e., the lower right corner of the first subscan region 3106a and the upper left corner of the second subscan region 3106b, as shown in Figure 31) is 41% larger than either the first or second frequency range gap. Furthermore, the closest point between subscan regions 3106a and 3106b is actually a point, not a line. Therefore, 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 in the first subscan region 3106a (i.e., within the first primary angular range 116a) with respect to a laser energy beam deflected in the second subscan region 3106b (i.e., within the second primary angular range 116b), the frequency of such distortion is much lower than if the beam distortion occurs only at one corner of the subscan region rather than along the entire edge of the subscan region. However, it can be understood that the size of one or both of the first and second frequency range gaps can be increased or decreased independently or in conjunction as needed, depending on the sensitivity (or insensitivity) of the workpiece processing to such distortion.

[0200] The above has described the arrangement of subscan regions consisting of a pair of identically sized square subscan regions 3106a and 3106b that are spatially offset from each other in a first direction (for example, by an angle corresponding to a first frequency range gap) and a second direction (for example, by an angle corresponding to a second frequency range gap), as shown in Figure 31. However, it can be understood that other embodiments are also possible.

[0201] For example, the arrangement of subscan regions 3106a and 3106b may differ from the arrangement shown in Figure 31 (for example, as shown in Figure 32). In other examples, the frequency range over which the AOD is driven may be selected to generate more than two square subscan regions, or to generate one or more subscan regions of shapes other than squares (e.g., rectangles, circles, ellipses, triangles, hexagons, etc.), or to generate subscan regions of different sizes, or similar arrangements, or any combination thereof.

[0202] In other examples, referring to Figure 33, the first AOD 402 can be driven by a first applied RF drive signal having a drive frequency within the first frequency range 3300, and the second AOD 404 can be driven by a second applied RF drive signal having a drive frequency within the range of the corresponding second frequency range 3104a and 3104b described above. For this reason, in order to deflect the beam path 114 incident on the multi-axis AOD system 400 within the first primary angle range 116a (to the second positioner 108a), the first RF drive signal applied to the first AOD 402 may have a first drive frequency f1 within the first frequency range 3300, and the second RF drive signal applied to the second AOD 404 may have a second drive frequency f2 within the second frequency range 3104a. To deflect the beam path 114 incident on 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 a first frequency range 3300, and the second RF drive signal applied to the second AOD 404 may have a second drive frequency f2 within a second frequency range 3104b. By driving the first AOD 402 (by applying a first drive frequency within the first frequency range 3300 to the first AOD 402) and driving the second AOD 404 (by applying a second drive frequency within the second frequency range 3104a or the second frequency range 3104b to the second AOD 404), the resulting scan area of ​​the multi-axis AOD system 400 is effectively divided into multiple subscan areas (i.e., the first subscan area 3302a and the second subscan area 3302b). It will also be understood that the AODs of the multi-axis AOD system 400 can be similarly driven by applying drive frequencies within the ranges illustrated in Figure 34.

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

[0204] ii. Embodiments relating to pulse slicing As described above, the first positioner 106 can be operated to perform pulse slicing, that is, to temporally divide a common laser pulse (also referred to herein as the “mother laser pulse”) into at least two laser pulses. Hereinafter, the temporally divided portions of the common mother laser pulse are also referred to as “pulse slices.” One embodiment of pulse slicing is illustrated in Figure 35, where the mother laser pulse 3500 is temporally divided into two pulse slices. Specifically, the mother laser pulse 3500 is divided into a first pulse slice 3500a during a first slice period p1, and the mother laser pulse 3500 is divided into a second pulse slice 3500b during a second slice period p2. As can be understood, the pulse duration of a pulse slice generally corresponds to the length of the slice period from which it is temporally divided from the mother laser pulse. Therefore, for example, the first pulse slice 3500a can be characterized as having a pulse duration equal to the first slice period p1, and the second pulse slice 3500b can be characterized as having a pulse duration equal to the second slice period p2.

[0205] The sequential slicing periods may occur continuously (i.e., one slicing period begins immediately after the preceding slicing period), or intermittently (i.e., one slicing period begins after a delay immediately following the preceding slicing period), or a combination of both. If the sequential slicing periods occur intermittently, it can be understood that the length of the delay can be characterized as an integer multiple of the positioning period of the first positioner 106 (this integer can be any integer such as 1, 2, 3, 4, 5, 10, 20, 50, 100, or any value in between). The embodiment shown in Figure 35 is an example where the sequential slicing periods p1 and p2 occur intermittently. The total time applied to a common mother laser pulse from the start of the first slicing period to the end of the last slicing 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). Therefore, the mother laser pulse can generally be characterized as having a pulse duration longer than the positioning period of the first positioner 106. In some embodiments, the pulse duration of the mother laser pulse may be 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 longer than, equal to, or shorter than values ​​in between these.

[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 (for example, this integer is 1, 2, 3, 5, 10, 20, 50, 100, 150, 200, 300, or a value in between). In one embodiment, the length of each slice period may be 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 longer than, equal to, or shorter than, values ​​in between these. Generally, 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, Figure 35 shows the first slicing period p1 as being equal to the second slicing period p2, but the length of the first slicing period p1 may be longer than or shorter than the second slicing period p2.

[0207] Outside the slicing period, the first positioner 106 can be operated in any manner known in the art to attenuate the incident laser energy beam so that when the laser energy beam propagating along the beam path 114 is finally deflected by the first positioner 106, it has insufficient energy to process the workpiece 102. In addition to or instead of this, outside the slicing period, the first positioner 106 can be operated to deflect the beam path 114 toward a beam trap, beam dump system, or any combination thereof, as described herein or known in the art. In embodiments in which the first positioner 106 is provided as an AOD system as described herein, outside of the slicing period, one or more AODs in the AOD system may be driven (or may not be driven) to direct the laser energy beam to a zero-order beampath (e.g., zero-order beampath 200 or 300), or to one or more higher-order beampaths (e.g., a second-order beampath, a third-order beampath, etc.), or to a beam trap, or to a beam dump system (e.g., an integrated beam dump system 700 or 1000, etc.), or to any combination thereof, as needed.

[0208] As described above, pulse slicing can be performed in conjunction with beam splitting, or it can be performed separately from beam splitting. Therefore, 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 (for example, to deflect different pulse slices to the same second positioner 108), or to deflect different pulse slices to different angles within different primary angle ranges 116 (for example, to deflect different pulse slices to different positioners of the second positioner 108), or to combine these arbitrarily. 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 (for example, to deflect the first pulse slice 3500a and the second pulse slice 3500b to the second positioner 108a). In other examples, the operation of the first positioner 106 may be controlled to deflect the first pulse slice 3500a by an angle within a first primary angular range 116a (for example, deflecting the first pulse slice 3500a to the second positioner 108a), and then deflect the second pulse slice 3500b by an angle within a second primary angular range 116b (for example, deflecting the second pulse slice 3500b to the second positioner 108b). Thus, a pulse slice 3500a having the optical power profile shown in Figure 35A can propagate to the second positioner 108a, and a pulse slice 3500b having the optical power profile shown in Figure 35B can propagate to the second positioner 108b.If 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) within any selected primary angular range 116 in any preferred or desired manner (for example, to compensate for a positioning error of the second positioner corresponding to the selected primary angular range 116, or to cause relative movement along the process trajectory between the process spot and the workpiece 102a during machining of the workpiece 102, or any combination thereof).

[0209] Figure 35 shows that the laser pulse 3500 is temporally divided into only two pulse slices (i.e., a first pulse slice 3500a and a second pulse slice 3500b), but it can be understood that the laser pulse 3500 may be temporally divided into more than two pulse slices (for example, into three pulse slices, five pulse slices, eight pulse slices, ten pulse slices, twenty-five pulse slices, thirty pulse slices, fifty pulse slices, etc., or similar pulse slices, or pulse slices with values ​​in between). For example, referring to Figure 36, the laser pulse 3500 may be temporally divided into four pulse slices 3600a, 3600b, 3600c, and 3600d. In one embodiment, the operation of the first positioner 106 is controlled so that the pulse slices that are divided sequentially are deflected within different primary angular ranges 116. For example, pulse slice 3600a can be deflected to a first primary angular range 116a, then pulse slice 3600b can be deflected to a second primary angular range 116b, then pulse slice 3600c can be deflected to the first primary angular range 116a, and then pulse slice 3600d can be deflected to the second primary angular range 116b. However, in other embodiments, the operation of the first positioner 106 is controlled so that pulse slices that are subsequently divided are deflected within the same primary angular range 116 or within different primary angular ranges 116. For example, pulse slice 3600a can be deflected to a first primary angular range 116a, then pulse slices 3600b and 3600c can be deflected to a second primary angular range 116b, and then pulse slice 3600d can be deflected to the first primary angular range 116a.

[0210] While pulse slicing has been described above in relation to a single mother laser pulse (i.e., laser pulse 3500), it can be understood that the first positioner 106 may be operated to perform pulse slicing with respect to a series of mother laser pulses that propagate sequentially. In this series of pulses, the sequentially propagating mother laser pulses may be temporally divided in any desired manner, and two sequentially propagating mother laser pulses may be temporally divided in the same or different manner.

[0211] In embodiments where the first positioner 106 is provided as a multi-cell AOD system, pulse slicing can be performed by the coordinated operation or driving of at least two AODs within the multi-cell AOD system. For example, referring to Figure 37, in embodiments where the multi-cell AOD system is provided as the AOD system 400 described above, the first AOD 402 and the second AOD 404 can be operated during the slicing period (for example, as described above) to deflect the beam path 114 within one or more of the primary angular ranges 116. The horizontal range of block 3700 indicates the period during which the first AOD 402 is operated to deflect the laser energy beam incident on the first AOD 402, and the horizontal range of block 3702 indicates the period during which the second AOD 404 is operated to deflect the laser energy beam incident on the second AOD 404. In Figure 37, the horizontal range of blocks 3700 and 3702 is equal to the slicing period (for example, the first slicing period p1, the second slicing period p2, etc., as described above).

[0212] However, in other embodiments, one or both of the first AOD402 and the second AOD404 may be operated for a period longer than the slicing period to deflect the beam path 114 within one or more of the primary angular range 116, but the periods during which they are driven overlap with the slicing period. See, for example, Figures 38, 39, 40, and 41.

[0213] iii. Discussion on diffraction efficiency As used herein, the term “diffraction efficiency” means the proportion of energy in the laser energy beam incident on the AOD that is diffracted into the primary beam within the AO cell of the AOD. Thus, diffraction efficiency can be expressed as the ratio of the optical power of the primary beam generated by the AOD to the optical power of the incident laser energy beam incident on the AOD. Generally, the amplitude of the applied RF drive signal can have a nonlinear effect on the diffraction efficiency of the AOD, and the diffraction efficiency of the AOD can also vary as a function of the frequency of the RF drive signal applied to drive the AOD. From this viewpoint, in embodiments 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 can be characterized as having a certain amplitude (also referred to herein as the “first amplitude”), and the second RF drive signal applied to drive the second AOD 404 can be characterized as having a certain amplitude (also referred to herein as the “second amplitude”).

[0214] Generally, the first amplitude can be selected or set based on one or more factors, such as the first drive frequency of the first RF drive signal, the first frequency range to which the first drive frequency belongs, the desired diffraction efficiency when the first AOD402 is driven by the first RF drive signal, the peak optical power of the deflected laser energy beam during the period in which the first AOD402 is driven by the first RF drive signal, the average optical power of the deflected laser energy beam during the period in which 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 the second drive frequency of the second RF drive signal, the second frequency range to which the second drive frequency belongs, the desired diffraction efficiency when the second AOD 404 is driven by the second RF drive signal, the peak optical power of the deflected laser energy beam during the period when the second AOD 404 is driven by the second RF drive signal, the average optical power of the deflected laser energy beam during the period when the second AOD 404 is driven by the second RF drive signal, or any combination thereof. When the AOD system 400 is operated to perform pulse slicing (for example, as described above), the first amplitude, the second amplitude, or a combination thereof may be selected or set as necessary based on the desired pulse duration of the pulse slices that are temporally divided from the laser energy beam.

[0215] In embodiments where the AOD system 400 is driven to perform beam splitting (for example, as described with respect to Figure 3, Figure 31, Figure 32, Figure 33, or Figure 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 a first frequency range 3102a. Similarly, if the first RF drive signal has a first drive frequency f1 within a first frequency range 3102b, the first RF drive signal can be characterized as having a first amplitude a1b. In this case, the first amplitude a1a may be higher than the first amplitude a1b, or the first amplitude a1a may be lower than or equal to the first amplitude a1b. Similarly, if the second RF drive signal has a second drive frequency f2 within a 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 a 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 may be lower than the second amplitude a2b, or the second amplitude a2a may be higher than or equal to the second amplitude a2b.

[0216] When the AOD system 400 is operated to perform beam splitting (for example, 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 beampath 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 beampath 114' deflected within the first AOD angular range 406b. While the primary beampath 114' is deflected within either the first AOD angular range 406a or 406b, the first amplitude of the first RF drive signal may vary or be maintained at a constant (or at least substantially constant) level. Similarly, the second amplitude of the second RF drive signal can be selected such that the optical power of the laser energy beam propagating along the primary beampath 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 beampath 114” deflected within the second AOD angular range 408b. While the primary beampath 114” is deflected within either the second AOD angular range 408a or 408b, the second amplitude of the second RF drive signal can vary or be maintained at a constant (or at least substantially constant) level.

[0217] IV. Conclusion The foregoing describes embodiments and examples of the present invention and should not be construed as limiting thereto. While several specific embodiments and examples have been described with reference to the drawings, those skilled in the art will readily recognize that many improvements are possible to the disclosed embodiments and examples and other embodiments without departing largely from the novel teachings and advantages of the present invention. Therefore, all such improvements are intended to fall 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 or paragraph, example or embodiment can be combined with the subject matter of some or all of the other sentences or paragraphs, examples or embodiments, unless such combinations are mutually exclusive. Therefore, the scope of the present invention should be determined by the following claims and their equivalents.

Claims

1. A laser source capable of generating a laser energy beam that can propagate along a beam path, A first positioner is positioned within the beam path and capable of deflecting the beam path, A controller connected to the first positioner and Equipped with, The controller is configured to control the operation of the first positioner so as to deflect the beam path within a first primary angular range and a second primary angular range, wherein the second primary angular range does not overlap with the first angular range and does not touch the first primary angular range. The controller is further configured to control the operation of the first positioner so as to deflect the beam path to a plurality of first angles within the first primary angle range and to a plurality of second angles within the second primary angle range. Laser processing equipment.

2. The apparatus according to claim 1, wherein the laser source is capable of generating a laser energy beam having wavelengths in the ultraviolet (UV) region of the electromagnetic wave spectrum.

3. The apparatus according to claim 1, wherein the laser source is capable of generating a laser energy beam having a wavelength in the long-wavelength infrared (LWIR) region of the electromagnetic wave spectrum.

4. The first positioner is, The first acousto-optic deflector (AOD), A second AOD is 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 the same axis. The apparatus according to claim 1.

5. A first scan head including a scan lens, A second scan head including a scan lens, At least one optical component arranged to guide the beam path deflected within the first angular range to the first scan head, At least one optical component arranged to guide the beam path deflected within the second angular range to the second scan head, The apparatus according to claim 1, further comprising:

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 includes a galvanometer mirror system.

8. Frame and, A pick-off mirror connected to the frame and configured to reflect the laser energy beam, A beam dump connected to the frame and configured to absorb the laser energy beam, An integrated beam dump system equipped with [the following features].

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

10. The integrated beam dump system according to claim 8, further comprising a relay mirror connected to the frame, the relay mirror being arranged to receive the laser energy beam reflected by the pick-off mirror and to 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. The frame comprises a first surface and at least one second surface, The first surface is configured to reflect the laser energy beam, The at least one second surface is configured to absorb the laser energy beam. Integrated beam dump system.

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

14. 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 being arranged to receive the laser energy beam reflected by the first surface and to reflect the received laser energy beam to at least one of the second surfaces.

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

16. The aforementioned frame is Optical input port, An optical output port arranged adjacent to the first surface and It further includes, The optical input port and the optical output port are arranged on a common axis through which the laser energy beam can propagate. The integrated beam dump system according to claim 12.

17. A wavefront correcting optical component comprising a mirror having a reflective surface, wherein the shape of the reflective surface is characterized by the Fringe-Zernike terms Z4 and Z9, and the ratio of the coefficient of the Z9 term to the coefficient of the Z4 term is in the range of -0.1 to -0.

3.

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 optical component according to claim 17, wherein the reflective surface is deformable.

20. It is equipped with a shape-changing mirror, and the shape-changing mirror is Reflective surface and, The main unit and Pockets defined within the main body and Includes, The main body includes a shape-variable membrane region between the reflective surface and the pocket. The central portion of the membrane region has a first thickness, and the peripheral portion of the membrane region has a second thickness that is greater than the first thickness. Wavefront correction optical component.

21. A base connected to the main body of the shape-changing mirror, further comprising a base having a perforation that penetrates the base, The aforementioned perforation is in fluid communication with the pocket, Wavefront correction optical component according to claim 20.

22. It is equipped with a shape-changing mirror, and the shape-changing mirror is Reflective surface and, A body including at least one rib, Multiple pockets defined within the main body and Includes, The main body includes a shape-variable membrane region between the reflective surface and the pocket. The at least one rib is positioned between the plurality of pockets, Wavefront correction optical component.

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

24. The wavefront correction optical component according to claim 22, wherein the main body includes a plurality of ribs.

25. A base connected to the body of the shape-changing mirror, further comprising a base having at least one perforation penetrating the base, The at least one of the perforations is in fluid communication with at least one of the plurality of pockets. Wavefront correction optical component according to claim 22.

26. A membrane-type shape-shifting mirror having a pressurizable pocket, A base connected to the mirror, having at least one perforation penetrating the base, the at least one perforation being in fluid communication with the pressurizable pocket, Mounting plate connected to the base and optical mount assembly A wavefront correction optical component system equipped with the above.

27. The base is inserted into the hole formed in the mounting plate. The at least one perforation extends into the hole formed in the mounting plate. The system according to claim 26.

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

29. The system according to claim 28, further comprising a hose connected to the end of the fitting.

30. A first optical component capable of transmitting a laser energy beam, which is susceptible to the thermal lensing effect, A wavefront compensating optical component configured to correct wavefront aberrations in the laser energy beam transmitted through the first optical component, which are wavefront aberrations caused by the thermal lensing effect, An optical relay system arranged and configured to relay the image of the first optical component in the first plane to the second plane. Equipped with, The wavefront compensating optical component is arranged in the second plane, The first optical relay system is configured such that the size of the image of the first optical component in the second plane is different from the size of the image of the first optical component in the first plane. system.

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

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

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

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

35. The system of claim 30, wherein the wavefront compensating optical component includes a static wavefront compensating optical component.

36. The system of claim 30, wherein the wavefront compensating optical component includes a dynamic wavefront compensating optical component.

37. The system further comprises a second optical component capable of transmitting the aforementioned laser energy beam, The optical relay system is arranged and configured to relay the image of the first optical component in the second plane to the third plane. The second optical component is arranged in the third plane, The system according to claim 30.

38. The optical relay system according to claim 37, wherein the size of the image of the first optical component in the second plane is the same as the size of the image of the first optical component in the third plane.

39. The wavefront compensating optical component is configured to reflect the laser energy beam, The aforementioned optical relay system is, A first optical relay including two lenses, A second optical relay including two lenses and including, The system according to claim 37.

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

41. The optical relay system further includes at least one mirror positioned between the two lenses of the second optical relay, according to claim 39.

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

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

44. The system of claim 37, wherein the first optical component includes an acousto-optics (AO) cell, and the second optical component is arranged 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 first optical component includes an acousto-optics (AO) cell capable of transmitting a first laser energy beam along the primary beam path and a second laser energy beam along the zeroth beam path. The second optical component is arranged such that the zero-order beam path of the AO cell of the first optical component is incident on the second optical component. The system according to claim 44.

46. The optical relay system includes a lens positioned on the zero-order beam path of the first optical component, wherein the lens is not part of the first optical relay or the second optical relay, according to claim 45.

47. an acousto-optic deflector (AOD); A dispersion compensator comprising at least one selected from the group consisting of prisms and gratings, A first optical component optically connected to the dispersion compensator at an optically upstream position of the dispersion compensator, the first optical component configured to expand the incident laser energy beam, A second optical component optically connected to the dispersion compensator and the AOD at a position optically between the dispersion compensator and the AOD, the second optical component configured to reduce the incident laser energy beam. A system that includes these features.

48. An acousto-optic deflector capable of diffracting an incident laser energy beam and outputting the diffracted laser energy beam along a beam path, wherein the acousto-optic deflector (AOD) is 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 prisms and gratings, the first dispersion compensator being optically coupled to the output of the AOD and positioned on the beam path deflected within a first angular range, A second dispersion compensator comprising at least one selected from the group consisting of prisms and gratings, wherein the second dispersion compensator is optically coupled to the output of the AOD and positioned on the beam path deflected within the second angular range. A system that includes these features.

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

50. The system of claim 49, further comprising a second positioner optically coupled to the 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 laser energy beam that can propagate along a beam path, A positioner positioned within the beam path and capable of deflecting the beam path, and a positioner including a first acousto-optic deflector (AOD) and a second AOD optically coupled to the output of the first AOD, A controller connected to the positioner, configured to operate the first AOD and the second AOD so as to temporally divide the laser energy beam into at least one pulse slice during at least one slice period. A system that includes these features.

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 pulsed slices during a plurality of slice periods, the sequentially occurring slice periods occurring intermittently.

53. 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. 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 pulsed slices for a period of time longer than the slicing period.

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