Method and apparatus for compensating for thermally induced beam pointing errors in a laser processing system

Abstract

A laser processing system for processing a workpiece is adapted to predict a thermal response of at least one of a number of beam path components to a laser energy beam during a predetermined processing interval as the workpiece is being processed, generate one or more commands based at least in part on the predicted thermal response, and output the one or more commands to one or more components of the system to process the workpiece during the processing interval.

Description

[Technical Field]

[0001] background I.Technical field FIELD OF THE INVENTION Embodiments of the present invention relate generally to systems and methods for positioning a laser energy beam, and more particularly, for positioning a laser energy beam to compensate for thermally induced beam pointing errors. [Background technology]

[0002] II. Description of Related Art Laser processing systems generally use a laser to process (e.g., cut, weld, drill, etc.) a workpiece, such as a printed circuit board, a metal plate, etc. Such systems typically include a beam positioning system (e.g., a pair of galvanometer mirrors oriented orthogonally to each other) for scanning or positioning the laser energy beam relative to the workpiece, and optical elements such as a scan lens for focusing the scanned laser energy beam on or near the workpiece. Other optical elements (e.g., mirrors, lenses, beam expanders, wave plates, polarizers, acousto-optic devices, etc.) are typically positioned in the beam path between a laser source (which generates the laser energy beam) and the beam positioning system. Optical elements such as a scan lens are often positioned in the beam path optically downstream of the beam positioning system to focus the laser energy beam on the workpiece, for example, so that the beam waist of the focused laser energy beam is located on or near the workpiece.

[0003] The optical elements in the laser processing systems described above typically absorb a portion of the optical power in the laser energy beam, which converts the absorbed optical power to heat within the optical elements. If the laser energy beam is sufficiently high-power (e.g., greater than 100 W), the absorbed optical power can induce thermal lensing or aberrations within some of the optical elements themselves. If the thermal gradients within the optical elements are relatively stable during workpiece processing, thermal lensing and other distortions or aberrations can typically be taken into account to ensure that the workpiece is processed successfully. However, the stability of the thermal gradient can be weakened by one or more factors related to the operation of the system, such as changes in the optical power used to process the workpiece or a temporary cessation of the propagation of laser energy through the scan lens (e.g., when switching to a new workpiece to be processed). If the thermal gradients within the optical elements are not sufficiently stable (i.e., "unstable"), the spatial deviation between the intended location of the beam waist of the laser energy beam relative to the workpiece and the location where the beam waist actually reaches the workpiece (i.e., "thermally induced beam pointing error") can become undesirably large. The absorbed optical power can also induce thermal distortions in mounting devices used to precisely position or orient optical elements within a laser processing system, which can also lead to thermally induced beam pointing errors.

[0004] One approach to avoiding thermally induced beam pointing errors is to design and operate a laser processing system so that the optical elements in the system are thermally stable when a workpiece is being processed. Generally, this solution requires that all optical elements in the system be exposed to a constant optical power from the laser energy beam, which is not always feasible. Other approaches to avoiding thermally induced beam pointing errors typically involve measuring the temperature of optical elements (e.g., galvanometer mirrors, scan lenses) in the beam path (e.g., with a temperature sensor) and adjusting the operation of the beam positioning system based on the measured temperature. However, such approaches cannot adequately accommodate gradual or sudden changes in the measured temperature. Summary of the Invention

[0005] overview One embodiment of the present invention can be broadly characterized as a laser processing system for processing a workpiece. The system can include a laser source operative to output a beam of laser energy propagable along a beam path and a plurality of beam path components disposed within the beam path. The plurality of beam path components can include a beam positioning system operative to deflect the beam path within a scan field in response to a position command, and a scan lens disposed to focus the beam laser energy deflected by the beam positioning system to thereby generate a focused laser energy beam having a beam waist. The system can further include a controller communicatively coupled to the beam positioning system. The controller can be configured to generate the position command based at least in part on a predicted thermal response of at least one of the plurality of beam path components to the laser energy beam during a predetermined processing interval, and to output the generated position command to the beam positioning system to operate the beam positioning system during the processing interval.

[0006] Another embodiment of the present invention can be broadly characterized as a laser processing system for processing a workpiece. The system can include a laser source operative to output a beam of laser energy propagable along a beam path and a plurality of beam path components disposed within the beam path, the plurality of beam path components including a scan lens disposed to focus the beam of laser energy deflected by the beam positioning system, thereby generating a focused laser energy beam having a beam waist. The system can further include at least one stage operative to impart relative movement between the beam waist and the workpiece in response to stage position commands, and a controller communicatively coupled to the at least one stage beam positioning system. The controller can be configured to generate the stage position commands based at least in part on a predicted thermal response of at least one of the plurality of beam path components to the beam of laser energy during a predetermined processing interval, and to output the generated stage position commands to the at least one stage to operate the at least one stage during the processing interval. [Brief explanation of the drawings]

[0007] BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1] FIG. 1 is a schematic diagram illustrating a laser processing system according to various embodiments of the present invention.

[0008] [Figure 2] FIG. 2 shows an embodiment of a beam modulator that can be incorporated into the laser processing system shown in FIG.

[0009] [Figure 3] FIG. 3 illustrates a laser beam monitoring system that may be incorporated as part of the laser processing system shown in FIG. 1, according to one embodiment of the present invention.

[0010] [Figure 4] FIG. 4 illustrates a schematic diagram of an application analysis module implemented by the controller shown in FIG. 1, according to one embodiment of the present invention.

[0011] [Figure 5] FIG. 5 is a schematic illustration of the thermal compensation module shown in FIG. 4, according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Detailed Description Examples of embodiments will now be described with reference to the accompanying drawings, in which, unless explicitly stated, the sizes, positions, etc. of components, features, elements, etc., and distances therebetween, are not necessarily drawn to scale and are exaggerated for clarity.

[0013] The terms used in the specification are for the purpose of describing particular exemplary embodiments only and are not intended to be limiting. As used herein, the singular is intended to include the plural unless the content clearly dictates otherwise. Furthermore, it should be understood that the terms "comprises" and / or "comprising," when used herein, identify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Unless otherwise indicated, when a range of values ​​is described, the range includes the upper and lower limits, as well as any subranges between the upper and lower limits of the range. Unless otherwise indicated, terms such as "first" and "second" are used merely to distinguish elements from one another. For example, one node may be referred to as a "first node," and similarly, another node may be referred to as a "second node," or vice versa. Section headings used herein, unless otherwise noted, are for organizational purposes only and should not be construed as limiting the subject matter described.

[0014] Unless otherwise indicated, "about," "around," and the like means that amounts, sizes, formulations, parameters, and other quantities and properties are not, and need not be, exact and may be approximate and / or larger or smaller, as appropriate, or to reflect tolerances, conversion factors, rounding, measurement error, and the like, as well as other factors known to those skilled in the art.

[0015] Spatially relative terms such as "below," "down," "lower," "upper," and "above" may be used herein for ease of description when describing the relationship of an element or feature to other elements or features, as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations in addition to those depicted in the figures. For example, an element described as being "below" or "below" another element or feature would be oriented "above" the other element or feature if the object in the figure were inverted. Thus, the exemplary term "below" can encompass both an upward and downward orientation. If an object is oriented in another way (e.g., rotated 90 degrees or at another orientation), the spatially relative descriptors used herein may be interpreted accordingly.

[0016] Like numbers refer to like elements throughout the drawings, and thus, the same or similar numbers may be described with reference to other drawings even if they are not mentioned or described in the corresponding drawing, and elements without a reference number may be described with reference to other drawings.

[0017] It will be understood that many different forms and embodiments are possible without departing from the spirit and teachings of this disclosure, and that this disclosure should not be construed as limited to the example embodiments set forth herein. Rather, these examples and embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0018] I. Generally, embodiments relating to laser processing systems and related components 1, a laser processing system for processing a workpiece 101, such as system 100, includes a laser source 102, a beam modulator 104, one or more optical elements 106, a beam positioning system 108, a scan lens 110, and a controller 112. System 100 may also include a workpiece stage 114 for positioning or holding workpiece 101.

[0019] 1, laser energy output by laser source 102 propagates along beam path 103 (represented by a dashed-dotted line). Beam modulator 104, optical element(s) 106, beam positioning system 108, and scan lens 110 are disposed within beam path 103. As used herein, the term "beam path" refers to the path that the laser energy beam actually traverses as it propagates from laser source 102 to (and through) scan lens 110 (e.g., to workpiece 101), and also refers to the path that the laser energy beam would traverse when output by laser source 102. Optical element(s) 106, beam positioning system 108, and scan lens 110 are collectively referred to herein as "beam path components."

[0020] Generally, the laser source 102 is configured to generate a high-power laser energy beam and may be provided as a CO laser source, a CO laser source, a high-power fiber laser, a high-power disk laser, or the like. The laser source 102 outputs a laser energy beam, represented as a train of laser pulses or as a continuous wave (CW) or quasi-CW (QCW) laser energy beam. As used herein, characterizing a laser energy beam as being "high-power" indicates that the optical power in the laser energy beam is sufficient to induce beam pointing errors in one or more of the beam path components described above. In certain embodiments, a high-power laser energy beam, represented as a train of laser pulses, may be characterized as having a peak power of 1 kW or greater (e.g., 1.5 kW, 2 kW, 3 kW, etc., or greater than or equal to any value between these values). In other embodiments, a high power laser energy beam, referred to as a CW or QCW laser energy beam, may have an average power of 100 W or more (e.g., 150 W, 200 W, 300 W, 400 W, 500 W, etc., or any value between these values ​​or more). It will be appreciated that these power values ​​may vary depending on other factors, such as the wavelength or pulse duration of the laser energy beam, the pulse repetition rate, the beam diameter, the optical absorption characteristics of beam path components, or any combination thereof.

[0021] The beam modulator 104 operates to selectively and variably attenuate the laser energy beam output by the laser source 102 (e.g., in response to one or more control signals output by the controller 112). Once the laser energy beam is output from the beam modulator 104, it propagates from the beam modulator 104 along a beam path 103 to other components of the system 100 and ultimately to the workpiece 101. Examples of the beam modulator 104 include one or more systems such as a variable neutral density filter, an acousto-optic (AO) modulator (AOM), an AO deflector (AOD), an electro-optic (EO) modulator (EOM), an EO deflector (EOD), a liquid crystal variable attenuator (LCVA), a microelectromechanical system (MEMS) based VOA, an optical attenuator wheel, a polarizer / waveplate filter, or the like, or any combination thereof. The degree of attenuation that can be imparted to the laser energy beam by the beam modulator 104 can range from 0% to 100%, depending on the configuration of the beam modulator 104. As such, the beam modulator 104 can be selectively and variably operated to transmit some or all of the laser energy beam incident on the beam modulator 104 to the remaining beam path components or to completely block the transmission of the beam path components. In certain embodiments, the beam modulator 104 can operate as a "pulse picker" (e.g., to selectively transmit only some pulses in a train of laser pulses in the laser energy beam) or as a "pulse slicer" (e.g., to selectively transmit only one or more portions of one or more laser pulses, or to split a CW or QCW laser energy beam into multiple pulses).

[0022] In one embodiment, referring to FIG. 2, the beam modulator 104 may be provided as an AO device 200 , such as an AOM or AOD, and a driver circuit 202 electrically coupled to the AO device 200 .

[0023] AO device 200 includes an AO cell and at least one ultrasonic transducer attached to the AO cell, as known in the art. Generally, the material forming the AO cell depends on the wavelength of the laser energy beam to be attenuated. For example, if the laser energy beam has a wavelength in the range of 2 μm (or thereabouts) to 20 μm (or thereabouts), the AO cell may be formed from a material including crystalline germanium, as known in the art.

[0024] The drive circuit 202 may include one or more RF combiners and one or more amplifiers coupled to the outputs of the one or more RF combiners. Each RF combiner may be configured to generate an RF signal having any desired or suitable waveform, and each amplifier may be configured to amplify the RF signal output by the RF combiner and output an amplified RF signal. The amplified RF signal may be output as a drive signal to at least one transducer of the AO device 200.

[0025] As will be appreciated by those skilled in the art, AO devices such as AO device 200 modulate a laser energy beam incident on and propagating through an AO cell using diffraction events caused by one or more acoustic waves simultaneously propagating through the AO cell. In this case, acoustic waves can be launched into the AO cell by applying a drive signal to at least one transducer of AO device 200, as is known in the art. Diffraction of the incident laser energy beam produces a diffraction pattern that typically includes a zeroth-order diffraction peak and a first-order diffraction peak, and may also include other higher-order diffraction peaks (e.g., second-order, third-order, etc.). The amount of optical power diffracted into the first-order diffraction peak (e.g., compared to the zeroth-order diffraction peak) can be affected by one or more factors, such as the amplitude of the drive signal applied to at least one transducer of AO device 200, the frequency of the drive signal applied to at least one transducer of AO device 200, and, if multiple transducers are provided, the phase relationship between the drive signals simultaneously applied to the transducers of AO device 200. As is known in the art, the portion of the diffracted laser energy beam in the zeroth order diffraction peak is referred to as the "zeroth order" beam, the portion of the diffracted laser energy beam in the first order diffraction peak is referred to as the "first order" beam, and so forth.

[0026] Generally, the zero-order beam and other diffracted beam orders (e.g., first-order beams) propagate along different beam paths upon exiting 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 beam path, the first-order beam propagates along the first-order beam path, and so on. In FIG. 2 , the zero-order beam path is identified as 204, and the first-order beam path is identified as 206. As known in the art, the angle Θ (also referred to herein as the “deflection angle”) between the zero-order beam path 204 and the first-order beam path 103 can depend on one or more factors, such as the frequency of a drive signal applied to at least one transducer of the AO device 200. Although not shown, one or more beam traps may be provided to absorb or block laser energy propagating along the zero-order beam path 204 (and other higher-order beam paths) while allowing laser energy propagating along the first-order beam path 206 to proceed to various other components of the system 100 and ultimately to the workpiece 101. Thus, primary beam path 206 corresponds to beam path 103 shown in FIG. 1 at all positions optically downstream of beam modulator 104 .

[0027] In one embodiment, beam modulator 104 may be provided as a series of AO devices, such as AO device 200, arranged optically in series to deflect a laser energy beam propagating along beam path 103 within a two-dimensional scan field (e.g., relative to beam positioning system 108). For example, beam modulator 104 may be provided as a first AO device and a second AO device arranged optically “downstream” of the first AO device. Similar to AO device 200, each of the first and second AO devices may be electrically coupled to a driver circuit, such as driver circuit 202. The first AO device may be positioned and operative to deflect beam path 103 (e.g., relative to beam positioning system 108) within a first one-dimensional scan field of the two-dimensional scan field (e.g., within a one-dimensional scan field extending along a first axis, such as the X-axis). The second AO device may be positioned and operative to deflect beam path 103 (e.g., relative to beam positioning system 108) within a second one-dimensional scan field of the two-dimensional scan field (e.g., within a one-dimensional scan field extending along a second axis, such as the Y-axis). In this case, the first AO device diffracts the incident laser energy beam propagating from laser source 102, and the second AO device diffracts the first order beam generated by the first AO device. Although not shown, one or more beam traps are provided to absorb or block laser energy propagating along all beam paths other than the first order beam path from each of the first and second AO devices.

[0028] 1 , the optical element(s) 106 may include one or more components such as beam expanders, beam shapers, beam splitters, apertures, filters, collimators, lenses, mirrors, prisms, polarizers, phase retarders, diffractive optical elements, refractive optical elements, etc., or any combination thereof, to focus, expand, collimate, shape, polarize, filter, split, combine, crop, or otherwise modify, condition, absorb, reflect, diffract, refract, or otherwise act on the laser energy beam as it propagates along the beam path 103 from the beam modulator 104 to the beam positioning system 108. Although not shown, one or more optical elements 106 may also be disposed in the beam path 103 between the laser source 102 and the beam modulator 104. The optical element(s) 106 may be positioned in the beam path 103 using one or more associated devices, such as a housing, bracket, mount, frame, stage, etc. (each collectively referred to as a "mounting device"), as known in the art. Such mounting devices may then be attached to a frame (not shown) of the system 100 by any suitable method or by any method known in the art. For purposes of discussion, a mounting device will be considered to be part of its associated optical element 106.

[0029] Beam positioning system 108 operates to reflect, diffract, and / or refract (e.g., in response to one or more control signals output by controller 112) the incident laser energy beam propagating along beam path 103 to deflect beam path 103 (e.g., relative to scan lens 110) within a scan field extending along one or more axes (e.g., along the X-axis shown in FIG. 1 , along a Y-axis perpendicular to the X-axis and Z-axis shown in FIG. 1 , etc., or along any combination thereof). In one embodiment, beam positioning system 108 is implemented as a pair of galvanometer mirrors arranged in optical series. In certain embodiments, beam positioning system 108 may include one or more components such as galvanometer mirrors, fast steering mirrors, AODs, EODs, MEMS-based scanning systems, etc., or any combination thereof. For example, beam positioning system 108 may include a first galvanometer mirror positioned and operative to deflect beam path 103 within a first scan field extending along the X-axis, and a second galvanometer mirror positioned and operative to deflect beam path 103, previously deflected within the first scan field by the first galvanometer mirror, within a second scan field extending along the Y-axis. In this manner, beam positioning system 108 having the first and second galvanometer mirrors is configured to deflect beam path 103 within a two-dimensional scan field. It should be understood that when beam path 103 is deflected within the scan field of beam positioning system 108, the beam waist of the focused laser energy beam (as ultimately irradiated onto workpiece 101) necessarily lies or is positioned within the scan field of beam positioning system 108.Furthermore, in embodiments in which the beam modulator 104 is configured and operative to deflect the beam path 103 (e.g., as described above), it should be understood that the scan field associated with the beam modulator 104 is superimposed on the scan field of the beam positioning system 108 (e.g., such that the beam positioning system 108 deflects the scan field of the beam modulator 104).

[0030] In general, scan lens 110 is configured to focus the laser energy beam propagating along beam path 103 (e.g., so that a beam waist of the focused laser energy beam is located on or near workpiece 101). As such, scan lens 110 can be thought of as configured to focus the scan field of beam positioning system 108 onto workpiece 101. Scan lens 110 may be provided as an f-theta scan lens, a telecentric f-theta scan lens, or the like. In another embodiment, scan lens 110 may be replaced with a concave mirror positioned to reflect the laser energy beam onto workpiece 101 and focus the reflected laser energy beam.

[0031] Although not shown, system 100 may optionally include at least one optical stage positioned and operative to move scan lens 110 (e.g., in response to one or more control signals output by controller 112). For example, the at least one optical stage may be operative to translate scan lens 110 along one or more of an X-axis, a Y-axis, or a Z-axis, rotate scan lens 110 about one or more of an X-axis, a Y-axis, or a Z-axis, the like, or any combination thereof. In this case, scan lens 110 may be incorporated into a housing such as scan head 116 that houses beam positioning system 108, and the at least one optical stage may be mechanically coupled to scan head 116.

[0032] The workpiece stage 114 may include a chuck (e.g., a vacuum chuck, an electrostatic chuck, a mechanical chuck, etc.) capable of preventing or minimizing movement of the workpiece 101 when the workpiece 101 is supported on the workpiece stage 114. Additionally, the workpiece stage 114 may be implemented as one or more motion stages positioned and operative to move the workpiece 101 (e.g., in response to one or more control signals output by the controller 112). For example, the workpiece stage 114 may be operable to translate the workpiece 101 along one or more of an X-axis, a Y-axis, or a Z-axis, rotate the workpiece about one or more of an X-axis, a Y-axis, or a Z-axis, or the like, or any combination thereof.

[0033] The controller 112 operates to generate and output one or more control signals to one or more components of the system 100, such as the laser source 102, the beam modulator 104, the beam positioning system 108, the workpiece stage 114, the optical stage, etc., or any combination thereof, to control the operation of such component(s) in any suitable manner or manner known in the art.

[0034] According to an embodiment of the present invention, the control signals output by the controller 112 communicate commands generated by an application analysis module of the controller 112. The application analysis module (not shown) operates to access a computer file containing a set of application data describing (e.g., in terms of size, shape, location, orientation, etc.) one or more features (e.g., slots, trenches, vias, holes, openings, scribe lines, etc.) to be formed in the workpiece 101 during processing of the workpiece 101. In one embodiment, the computer file may also include workpiece data describing certain characteristics of the workpiece 101 being processed (e.g., in terms of type, material composition, dimensions, etc.). In other embodiments, the workpiece data may be added to or associated with the set of application data via user interaction with a user interface (not shown) of the system 100. The application analysis module operates in any suitable manner known in the art to process or analyze the application data and workpiece data (e.g., as described in a computer file) to obtain, acquire, or generate (by any suitable manner or manner known in the art) a set of commands intended to coordinate and control the operation of one or more components of system 100 (e.g., laser source 102, beam modulator 104, beam positioning system 108, optical stage, workpiece stage 114, etc., or any combination thereof) so that workpiece 101 is processed to form feature(s) therein.

[0035] For example, the application analysis module may generate one or more commands that, when output to the laser source 102, cause the laser source 102 to output a laser energy beam having a particular average power, peak power, temporal power profile, pulse duration, duty cycle, etc. The commands output to the laser source 102 are collectively referred to as "laser commands." Laser commands intended to control the average power, instantaneous power, or peak power of the output laser energy beam are generally referred to herein as "laser power commands."

[0036] In another example, the application analysis module may output one or more commands that, when output to the beam modulator 104, cause the beam modulator 104 to attenuate the optical power of the laser energy beam incident thereon. If desired, the degree to which the laser energy beam is attenuated may take into account one or more factors, such as the average power, peak power, temporal power profile, pulse duration, etc. of the laser energy beam output by the laser source 102, predetermined known optical absorption characteristics of beam path components, etc., or any combination thereof. Such commands output to the beam modulator 104 are referred to as "transmission commands."

[0037] In an embodiment in which the beam modulator 104 is implemented as the AO device 200 and driver circuitry 202 described above with respect to FIG. 2, to the extent that the frequency of the drive signal applied to the at least one transducer of the AO device 200 can vary the deflection angle Θ, the application analysis module is operative to generate and output one or more commands to the driver circuitry 202 to vary at least one frequency of the one or more drive signals applied to the at least one transducer of the AO device 200 (e.g., to deflect the beam path 103 to a desired position). Such commands would be output to the driver circuitry 202 simultaneously with one or more corresponding transmission commands (e.g., as described above) and are referred to as "frequency modulation position commands." In embodiments in which the beam modulator 104 is provided as one or more of the AO devices (and associated drive circuits) described above, to the extent that the deflection angle Θ can be varied by varying the frequency of the drive signal applied to at least one transducer of the AO device, the application analysis module may output a first frequency modulation position command to the drive circuit associated with the first AO device and a second frequency modulation position command to the drive circuit associated with the second AO device.

[0038] In another example, the application analysis module may output one or more commands that, when output to the beam positioning system 108, cause the beam positioning system 108 to deflect the beam path 103 within its scan field (e.g., at a desired speed, to a desired position, etc.). Such commands output to the beam positioning system are collectively referred to as “beam position commands.” In embodiments in which the beam positioning system 108 is implemented as a pair of galvanometer mirrors as described above, the application analysis module may output a first beam position command to the first galvanometer mirror and a second beam position command to the second galvanometer mirror. Because the beam position command and the frequency modulation position command described above may affect the relative position between the workpiece 101 and the beam waist of the focused laser energy beam propagating from the scan lens 110, the beam position command and the frequency modulation position command described above may be considered different embodiments of a “position command.”

[0039] In another example, the application analysis module may output one or more commands to the optical stage, causing the optical stage to move the scan lens 110 or the scan head 116 (e.g., at a desired velocity, to a desired position, etc.). Such commands output to the optical stage system are referred to as "optical stage position commands." In yet another example, the application analysis module may output one or more commands to the workpiece stage 114, causing the workpiece stage 114 to move the workpiece 101 (e.g., at a desired velocity, to a desired position, etc.). Such commands are referred to as "workpiece stage position commands." The optical stage position commands and the workpiece stage position commands may be collectively referred to herein as "stage position commands." Because the stage position commands may affect the relative position between the workpiece 101 and the beam waist of the focused laser energy beam propagating from the scan lens 110, the stage position commands may be considered a different embodiment of a "position command."

[0040] The control signals conveying the above-described commands may be coordinated and sequentially output (by any suitable method or methods known in the art) to process the workpiece 101 to form feature(s) therein. When the workpiece 101 is processed, a laser energy beam is applied to multiple locations on the workpiece 101 (e.g., as a series of laser pulses and / or as a CW or QCW laser energy beam). The total time during which workpiece 101 is processed may be at least conceptually divided into a series of processing periods of any duration or predetermined duration, which may take into account update rates of one or more of the above-described components of system 100, as needed. In one embodiment, a processing period may range from 0.5 μs (or thereabouts) to 150 μs (or thereabouts), such as 0.5 μs, 1 μs, 5 μs, 10 μs, 25 μs, 50 μs, 75 μs, 100 μs, 150 μs, etc., or values ​​between any of these values.

[0041] Generally, the controller 112 includes one or more processors that operate to generate the command and control signals described above (e.g., upon execution of one or more instructions). The processor may be implemented as a programmable processor (e.g., one or more general-purpose computer processors, microprocessors, digital signal processors, or any suitable form of circuitry (including digital, analog, or mixed analog / digital circuitry) including programmable logic devices (PLDs), central processing units (CPUs), graphics processing units (GPUs), advanced processing units (APUs), real-time processing units (RPUs), field programmable gate arrays (FPGAs), field programmable object arrays (FPOAs), application specific integrated circuits (ASICs), or the like) that operates to execute the instructions. Execution of the instructions may occur on a single processor, distributed across multiple processors, in parallel across multiple processors within a device or across a network of devices, or the like, or any combination thereof.

[0042] Generally, instructions may be embodied as software (e.g., executable code, files, library files, etc., or any combination thereof), hardware configurations (e.g., in the case of FPGAs, ASICs, etc.), or any combination thereof, which may be readily identified by one of ordinary skill in the art from the disclosure herein (written in a hardware description language such as C, C++, Visual Basic, Java, Python, Tel, Perl, Scheme, Ruby, assembly language, LUCID, VHDL, VERILOG, etc.). Software is typically stored in one or more data structures carried by tangible media, such as computer memory, accessible by a processor (e.g., via one or more wired or wireless communication links). Examples of tangible media include 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.), or any combination thereof, which may be locally accessible or remotely accessible (e.g., over a network), or any combination thereof.

[0043] It should be noted that various functions performed by the controller 112 are described as being performed by a module. This division of modules is for illustrative purposes only. In other embodiments, the functionality performed by a particular module may be divided among multiple modules. Also, in other embodiments, two or more modules described herein may be combined into a single module. Each module described herein may be implemented using hardware (e.g., an FPGA device, an ASIC, etc.), software (e.g., processor-executable instructions), or any combination thereof.

[0044] Although system 100 has been described above as including a single beam positioning system 108 and scan lens 110 (e.g., integrated within a single, common scan head 116), it will be appreciated that in other embodiments, system 100 may include multiple scan heads 116 (independently movable, if necessary, by separate optical stages), each having its own beam positioning system 108 and scan lens 110. In such other embodiments, an optical switch may be positioned and operable to selectively deflect beam path 103 (e.g., from the beam positioning system 108 of one scan head 116 to the beam positioning system 108 of another scan head 116, or vice versa). In this case, the optical switch would be positioned in beam path 103 either optically upstream or downstream of beam modulator 104 and communicatively coupled to controller 112 (e.g., to be able to deflect beam path 103 in response to one or more commands output by the application analysis module). Alternatively, in embodiments in which the beam modulator 104 is provided as a device capable of deflecting the beam path 103 (e.g., an AOM, AOD, EOM, EOD, etc. as described above), the beam modulator 104 may be operated to selectively deflect the beam path 103 from the beam positioning system 108 of one scan head 116 to the beam positioning system 108 of another scan head 116, and vice versa (e.g., in response to one or more frequency modulation position commands output by the application analysis module).

[0045] 1, system 100 may optionally include a laser beam monitoring system operative to measure the optical power or energy in the laser energy beam propagating along beam path 103. In one embodiment, the laser beam monitoring system may be provided as laser beam monitoring system 300 shown in FIG.

[0046] Referring to FIG. 3, laser beam monitoring system 300 includes mirror 302 and laser sensor 304. Mirror 302 is disposed within beam path 103 and is provided as a partially transmitting mirror configured to reflect a majority of the light in an incident laser energy beam propagating along beam path 103 (to beam path 103r) and transmit a small amount of light (e.g., 2% or thereabouts) to beam path 103t. In FIG. 3, mirror 302 may be disposed within beam path 103 anywhere optically “upstream” or “downstream” of beam modulator 104. In this case, beam path 103r corresponds to beam path 103 illustrated and described above with respect to FIG. 1. Laser sensor 304 is disposed to receive laser energy transmitted through mirror 302 (e.g., propagating along beam path 103t).

[0047] In one embodiment, the laser sensor 304 is configured to measure the instantaneous optical power in the laser energy beam incident thereon and generate sensor data based on the detection or measurement. The sensor data may be output to the controller 112 by any suitable means (e.g., via wired or wireless communication as known in the art). The controller 112 may store the sensor data (e.g., locally within the controller 112, on some computer memory within the system 100 accessible to the controller 112, or on some computer memory located remotely from the system 100 but communicatively connected to the system 100 via one or more networks). In other embodiments, the sensor data output to the controller 112 may be further processed (e.g., time-integrated) by the controller 112 to obtain energy components of the laser energy beam incident on the laser sensor 304 (e.g., over a predetermined period of time) and store the processed sensor data (e.g., as described above).

[0048] In other embodiments, the laser sensor 304 is implemented as an integrating detector (e.g., configured to measure the instantaneous optical power in a laser energy beam incident thereon and integrate the measured optical power to obtain the energy content of the beam) to generate sensor data, which may be output to the controller 112 by any suitable means (e.g., via wired or wireless communication as known in the art) and stored (e.g., as described above).

[0049] In certain embodiments, sensor data acquired, processed, obtained, stored, or accessible by the controller 112 may be monitored (e.g., periodically, during preventive maintenance periods, the like, or any combination thereof) to determine whether the laser source 102 is operating properly. If it is determined that the laser source 102 is not operating properly, the controller 112 may control the operation of the beam modulator 104 to compensate for the operation of the laser source 104. For example, if the sensor data indicates that the measured or obtained power or energy is below a target threshold, the controller 112 may adjust the operation of the beam modulator 104 to decrease the degree to which the beam modulator 104 attenuates the incident laser energy beam. Similarly, if the sensor data indicates that the measured or obtained power or energy is above a target threshold, the controller 112 may adjust the operation of the beam modulator 104 to increase the degree to which the beam modulator 104 attenuates the incident laser energy beam.

[0050] In embodiments in which the mirror 302 is located optically downstream of the beam modulator 104, and the beam modulator 104 is provided as described above with respect to Figure 2, the mirror 302 is located in the first order beam path 206. However, in other embodiments, the mirror 302 may be located in the zero order beam path 204.

[0051] II. EMBODIMENTS FOR COMPENSATION OF THERMALLY INDUCED BEAM POINTING ERRORS According to embodiments described herein, one or more of the beam path components described above absorb at least a portion of the energy in the high-power laser energy beam propagating from the beam modulator 104 along the beam path 103. This can reduce the stability of thermal gradients in the beam path components (e.g., depending on one or more factors related to the operation of the system, as described above), which can cause thermally induced beam pointing errors to occur that can adversely affect the accuracy and / or quality of processing of the workpiece 101.

[0052] The inventors have discovered that the thermally induced beam pointing errors described above can be generally categorized as errors associated with “drift,” “shift,” or “scaling.” As described in more detail below, embodiments of the present invention provide thermal compensation techniques that can compensate for (i.e., prevent or reduce the effects of) one or more of these thermally induced beam pointing errors much faster than the conventional techniques described above.

[0053] As used herein, "drift" refers to movement of the beam waist of the focused laser energy beam along one or more axes (e.g., the X and / or Y axes described above) of the scan field projected onto the workpiece 101 by the scan lens 110. Drift in one axis may differ from drift in other axes. Similarly, drift in any axis may vary from system 100 to system 100 and between different scan heads 116 of the same system 100 (e.g., depending on how the components in the beam path 103 of any system 100 are mounted and aligned). In some cases, heat buildup in optical components 106 (e.g., mirrors) or mounting devices associated with the optical components 106 can cause undesired drift.

[0054] As used herein, "shift" refers to a movement of the beam waist of the focused laser energy beam along the beam path 103 as it propagates from the scan lens 110. Generally, heat accumulation within the transmissive optical component 106 (e.g., a lens, prism, etc.) or the scan lens 110 can cause the beam waist to move away from the workpiece 110 (e.g., in a direction toward the scan lens 110), thereby changing (typically increasing) the size of the spot of the laser energy beam at the workpiece 101. Similarly, a loss of thermal energy within the transmissive optical component 106 or the scan lens 110 can cause the beam waist to move away from the scan lens 110 (e.g., in a direction toward the workpiece 101), thereby changing (typically decreasing) the size of the spot of the laser energy beam at the workpiece 101.

[0055] As used herein, "scaling" refers to the degree to which the intended size of the scan field projected by scan lens 110 is reduced or increased (e.g., by correspondingly shortening or lengthening the focal length of scan lens 110, as described above). Generally, heat buildup within scan lens 110 may reduce the scan field (e.g., beam positioning system 108) projected through scan lens 110 onto workpiece 101. Similarly, loss of thermal energy within scan lens 110 may expand the scan field (e.g., beam positioning system 108) projected through scan lens 110 onto workpiece 101.

[0056] To the extent that the thermally induced beam pointing errors described above can be undesirably large, embodiments of the present invention compensate for these effects, for example, by canceling out or minimizing or reducing thermally induced drift, shift and / or scaling.

[0057] A. Generally, embodiments relating to a thermal compensation module 4, in accordance with an embodiment of the present invention, the application analysis module includes a thermal compensation module 400 that operates to implement one or more thermal compensation techniques. As described in more detail below, the thermal compensation module 400 processes the laser power data 402 (and, optionally, the beam position data 404) to predict the thermal response (e.g., of one or more beam path components, or of the system 100 generally, or any combination thereof) during a given processing period. As used herein, "thermal response" is a measure of how quickly thermal gradients (e.g., in one or more beam path components, or of the system 100 generally, or any combination thereof) may build up, dissipate, or change during a given period (e.g., in the presence or absence of optical power in the laser energy beam) to result in one or more of the thermally induced beam pointing errors described above.

[0058] The thermal compensation module 400 may then apply one or more correction functions (also described in more detail below) to the predicted thermal response(s) and optionally input preliminary position commands 406 to generate one or more position command corrections 408. For example, in one embodiment shown in FIG. 5, the thermal compensation module 400 may include one or more thermal response modules 500 that operate to predict the thermal response of the system 100 and a correction function module 502 that operates to apply the correction function(s) to the predicted thermal response(s).

[0059] Because the thermal compensation technique does not involve measuring the temperature of any of the beam path components, system 100 does not include temperature sensors (e.g., thermocouples, thermistors, resistance temperature detectors, pyrometers, infrared thermometers, etc.) for measuring (directly or indirectly) the temperature of any of the above-mentioned beam path components of system 100, and can quickly and accurately compensate for thermally induced beam pointing errors during processing of workpiece 101.

[0060] The laser power data 402 represents, is associated with, or correlates to, the amount of optical power or energy in one or more of the beam path components during a particular processing period. The laser power data 402 may be obtained (e.g., by an application analysis module) or may correspond to a laser power command, a transmission command, sensor data, or the like, or any combination thereof.

[0061] The beam position data 404 represents or is associated with or correlates to the position of one or more of the beam path components of the beam path 103 during a particular processing period. The beam position data 404 may be obtained (e.g., by an application analysis module) from or correspond to a beam position command, a position command such as a frequency modulation position command, or the like, or any combination thereof.

[0062] If desired, any of the position commands described above (e.g., beam position commands, frequency modulation position commands, optical stage position commands, workpiece stage position commands, or any combination thereof) may be input to thermal compensation module 400 to facilitate prediction of the thermal response of system 100 during a given processing period. Such position commands input to thermal compensation module 400 are also referred to herein as "preliminary position commands" 406.

[0063] Generally, the position command correction values ​​408 output by the thermal compensation module 400 correspond to preliminary position commands associated with one or more of the beam path components, the beam modulator 104, or any combination thereof described above. Accordingly, the application analysis module operates to generate corrected position commands 412 by applying (e.g., adding as shown at 410) each position command correction value 408 generated by the thermal compensation module 400 to the corresponding preliminary position command 406. Applying the position command correction value 408 to the corresponding preliminary position command 406 adjusts the preliminary position command 406 based on the predicted thermal response of one or more of the beam path components during a given processing period, which adjustment compensates for one or more of the thermally induced beam pointing errors described above.

[0064] For example, one or more preliminary position commands 406 (e.g., first beam position command and / or first frequency modulation position command) may be adjusted 410 to compensate for predicted drift in the positive X-axis direction (i.e., toward the right as shown in FIG. 1 ) during a given processing period. This adjustment, when processed by the beam positioning system 108 or beam modulator 104, compensates for the predicted drift by generating one or more corrective position commands 412 that offset the predicted drift in the negative X-axis direction (i.e., toward the left as shown in FIG. 1 ) during a given processing period. While the above examples describe compensating for predicted drift in the positive X-axis direction, it should be understood that predicted drift in the negative X-axis direction can be compensated for in a similar manner. Furthermore, while the above examples describe compensating for predicted drift in the positive X-axis direction, it should be understood that compensation for predicted drift along the Y-axis can be performed in a similar manner.

[0065] In another example, one or more preliminary position commands 406 (e.g., first beam position command and / or first frequency modulation position command) may be adjusted 410 to compensate for predicted scaling that will cause a reduction in the size of the scan field along the X-axis during a given positioning period. This adjustment, when processed by the beam positioning system 108 or beam modulator 104, compensates for the predicted scaling by generating one or more correction position commands 412 that offset the predicted scaling by increasing the deflection of the beam path 103 along the X-axis during a given period. While the above example describes compensating for predicted scaling (i.e., reduction) of the size of the scan field along the X-axis, it should be understood that a predicted expansion of the size of the scan field along the X-axis may be compensated for in a similar manner. Furthermore, while the above example describes compensating for predicted scaling along the X-axis, it should be understood that compensation for predicted scaling (i.e., a reduction or expansion of the size of the scan field along the Y-axis) may be performed in a similar manner.

[0066] In another example, one or more preliminary position commands 406 (e.g., optical stage position commands and / or workpiece stage position commands) may be adjusted 410 to compensate for a predicted shift that will move the beam waist toward scan lens 110 during a given positioning period. This adjustment, when processed by the optical stage and / or workpiece stage 114, compensates for the predicted shift by generating one or more corrective position commands 412 that offset the predicted shift by moving scan lens 110 toward workpiece 101 and / or moving workpiece 101 toward scan lens 110 during a given period. While the above example describes compensating for a predicted shift toward scan lens 110 (i.e., in the positive or upward direction of the Z axis as shown in FIG. 1), it should be understood that a shift predicted to occur in the negative Z axis direction may be compensated for in a similar manner.

[0067] While the above examples describe exemplary processes that can generate and output corrective position commands 412 to compensate for thermally induced drift, shift, and scaling individually, it will be appreciated that these embodiments may be combined as needed or preferred to generate corrective beam position commands adapted to compensate for one or more of thermally induced drift, shift, and scaling along one or more axes. The application analysis module operates to output the corrective position command(s) 412 (e.g., as position commands conveyed by one or more control signals) to one or more of the beam modulator 104, the beam positioning system 108, the optical stage, the workpiece stage 114, or any combination thereof (e.g., in a coordinated manner as described above) to ensure that the workpiece 101 is processed during a given processing period in a manner that compensates for one or more of the thermally induced beam pointing errors described above.

[0068] B. Thermal Response Prediction Embodiments As described above, the thermal compensation module 400 processes the laser power data 402 (and optionally the beam position data 404) to predict one or more thermal responses of the system 100 during a given processing period, to the extent that the thermal response is associated with one or more of the thermally induced beam pointing errors described above.

[0069] In one embodiment, the thermal response of system 100 can be predicted by predicting the thermal response of one or more of the beam path components of system 100. Thus, for example, the thermal response of system 100 during an nth processing period can be described as the sum of all predicted thermal responses of the beam path components in system 100, e.g., given by the following function (1):

number

[0070] In one embodiment, the time constant α is set to 0 insofar as the thermally induced beam pointing error caused by the beam path components is a response of the beam path components to heat. i can be considered as a parameter that characterizes how quickly a thermally induced beam pointing error occurs in response to heat input. However, the inventors have discovered that, depending on the beam path components and / or the thermally induced beam pointing error, the thermally induced beam pointing error can occur due to multiple responses of the beam path components to the heat input. The multiple responses are associated with different time scales. Therefore, the time constant α i may be a single value, or if the thermally induced beam pointing error is caused by multiple responses, the time constant α i may be represented as a combination (eg, linear or otherwise) of multiple values ​​(eg, each value associated with one of different time scales).

[0071] In other embodiments, the time constant α can be adjusted to a value greater than 0.01, insofar as different thermally induced beam pointing errors caused by beam path components may occur on different timescales.i may be expressed as a combination (e.g., linear or otherwise) of multiple values ​​(e.g., each value associated with one of different time scales). However, in other embodiments, different time constants α (whether expressed as a single value as described above or as a combination of multiple values) may be used in different instances of function (1) to predict different thermal responses of system 100 during a given processing period. i may be used. For example, the first example of function (1) may be used to predict the thermal response of system 100 that will cause drift (i.e., the sum of the thermal responses of all beam path components). The second example of function (1) may be used to predict the thermal response of system 100 that will cause shift (i.e., the sum of the thermal responses of all beam path components). The third example of function (1) may be used to predict the thermal response of system 100 that will cause scaling (i.e., the sum of the thermal responses of all beam path components). If a beam path component does not contribute to a particular thermally induced beam pointing error, the time constant α for that beam path component may be used. i becomes zero. The first example of function (1) is also referred to herein as the "drift prediction function," the second example of function (1) is also referred to herein as the "shift prediction function," and the third example of function (1) is also referred to herein as the "scaling prediction function."

[0072] In another embodiment, a common time constant α (whether expressed as a single value as described above or as a combination of multiple values) is used in a common instance of function (1) to predict the thermal response of system 100 during a given processing period that will cause different thermally induced beam pointing errors to occur, to the extent that different thermally induced beam pointing errors caused by beam path components may occur on the same time scale. iFor example, a common instance of function (1) may be used to predict the common thermal response of system 100 (i.e., the sum of the thermal responses of all beam path components) that cause shift and scaling. The common instance of function (1) in this embodiment may also be referred to herein as the "shift / scaling prediction function." Again, if a beam path component does not contribute to any of the different thermally induced beam pointing errors, the time constant α for that beam path component may be used. i becomes zero.

[0073] As mentioned above, if a beam path component does not contribute to a particular thermally induced beam pointing error, the time constant α for that beam path component can be i will be zero. In another embodiment, if a beam path component contributes less than a predetermined threshold amount to a particular thermally induced beam pointing error, the contribution of the predicted thermal response for that beam path component is not included in each of functions (1). For example, the beam positioning system 108 may not contribute (or contribute less than a predetermined threshold amount) to shift and scaling, and therefore the predicted thermal response of the beam positioning system 108 need not be included in the shift and / or scaling prediction functions. In another example, the scan lens 110 may not contribute (or contribute less than a predetermined threshold amount) to drift, and therefore the predicted thermal response of the scan lens need not be included in the drift prediction functions.

[0074] Generally, each beam path optical component absorbs a portion of the optical power in the laser energy beam propagating along the beam path 103. Therefore, the laser power data P(n) for one beam path component during a given processing period may differ from the power data for a different beam path component during the same processing period. Furthermore, because the difference in the laser power data for at least two of the m beam path components may be relatively small or insignificant depending on the system configuration, in other embodiments the same laser power data associated with a given processing period may be used for at least two of the m beam path components.

[0075] In other embodiments, the thermal response of the entire system 100 can be predicted without explicitly accounting for the individual thermal responses of each beam path component of system 100. In this sense, the thermal response of system 100 is simply related to one or more thermally induced beam pointing errors detected (e.g., through direct or indirect observation, measurement, etc.) at the output position (e.g., at workpiece 101) relative to scan lens 110. Thus, the thermal response of system 100 during the nth processing period is given by the following function (2):

number

[0076] As will be appreciated, functions (1) and (2) above are examples of first-order infinite impulse response (IIR) filters. The filters may be implemented as digital filters, analog filters, or the like, or any combination thereof. However, embodiments of the present invention are not limited to the use of IIR filters to predict thermal responses associated with system 100. For example, other filters (whether implemented digitally or analogically) that may be used include biquad filters, Butterworth filters, or the like, or any combination thereof. The coefficients and orders of the filters implemented in each thermal response module 500 are selected or set empirically or by any suitable method or method known in the art.

[0077] C. Correction Function Embodiments As described above, the thermal compensation module 400 operates to apply one or more correction functions to the predicted thermal response(s) and, if necessary, the input preliminary position commands 406 to generate one or more position command corrections 408. Generally, the correction functions may be provided as any suitable function or combination of basis functions to model thermally induced beam pointing errors due to drift, shift, or scaling. Examples of suitable functions include a first-order linear regression function, an nth-order polynomial function (n being 2 or greater), etc.

[0078] The correction functions used to generate the position command corrections 408 may vary depending on the predicted thermal response to which the correction function is applied, the type of thermally induced beam pointing error being compensated for, the preliminary position command to which the correction function is adjusting, the like, or any combination thereof. Examples of correction functions that may be applied to compensate for drift in the X and Y axes during a given processing period n can be described by the following correction functions (3) and (4):

number

number

[0079] An example of a correction function that can be applied to compensate for a shift (eg, in the Z axis) during a given processing period n can be described by the following correction function (5):

number

[0080] Examples of correction functions that can be applied to compensate for scaling in the X and Y axes during a given machining period can be described by the following correction functions (6) and (7).

number

number

[0081] The coefficients of correction functions (3) through (7) may be empirically established, modeled, or determined (e.g., via system calibration) using suitable techniques or techniques known in the art. Furthermore, the coefficients of correction functions (3) through (7) may vary depending on the size, number, and density of features formed in workpiece 101, the placement of workpiece 101 on workpiece stage 114, the utilization of scan field(s) projected by scan lens 110, the position of the scan field (or the position of the scan field's center of gravity) within the scan lens during processing, the like, or any combination thereof.

[0082] III. Conclusion The foregoing is a description of embodiments and examples of the present invention and is not to be construed as limiting thereof. Although several specific embodiments and examples have been described with reference to the drawings, those skilled in the art will readily appreciate that many modifications to the disclosed embodiments and examples, as well as other embodiments, are possible without significantly departing from the novel teachings and advantages of the present invention.

[0083] For example, the embodiments described above provide systems and techniques for real-time compensation of thermally induced beam pointing errors. It will be appreciated that these embodiments may also be adapted for non-real-time compensation of thermally induced beam pointing errors. For example, the application analysis module may generate a set of preliminary position commands (e.g., as described above) necessary to form a feature in a desired configuration on the workpiece 101 and input these preliminary position commands to the thermal compensation module 400. The thermal compensation module 400 may process the preliminary position commands (e.g., as described above) in sets to generate a set of position command corrections 408. The application analysis module may then apply (e.g., at 410, as described above) each position command correction 408 to a corresponding preliminary position command to generate a set of corrected position commands 412. After the set of corrected position commands 412 is generated, the corrected position commands 412 may be sequentially output as described above (e.g., to the beam modulator 104, the beam positioning system 108, the optical stage and / or the workpiece stage 114) in a manner coordinated with commands output to other components of the system 100 (e.g., the laser source 102) so that the workpiece 101 is processed to form (one or more) features in the desired form on the workpiece 101.

[0084] In another example, although compensation for the predicted shift has been described above as being affected by adjusting the position of the optical stage and / or workpiece stage 114, it will be appreciated that the shift may be compensated for in other ways. For example, in embodiments in which the beam modulator 104 includes the first and second AO devices (and associated drive circuitry) described above, the beam modulator 104 may be operated to rapidly move the beam waist toward or away from the scan lens 110 by "chirping" the frequency of the drive signals applied to the first and second AO devices by any suitable method or method known in the art.

[0085] Accordingly, all such modifications are intended to be included within the scope of the present invention as defined in the claims. For example, those skilled in the art will understand that the subject matter of any sentence, paragraph, example, or embodiment may be combined with some or all of the subject matter of any other sentence, paragraph, example, or embodiment, except where such combinations would be mutually exclusive. The scope of the present invention should therefore be determined by the following claims and any equivalents of such claims to be included therein.

Claims

1. 1. A laser processing system for processing a workpiece, comprising: a laser source operative to output a beam of laser energy propagable along a beam path; a plurality of beam path components disposed in the beam path, a beam positioning system operative to deflect the beam path within a scan field in response to position commands; a scan lens positioned to focus the beam laser energy deflected by the beam positioning system, thereby producing a focused beam of laser energy having a beam waist; a plurality of beam path components including: a controller communicatively coupled to the beam positioning system, the controller configured to generate the position commands based at least in part on a predicted thermal response of at least one of the plurality of beam path components to the laser energy beam during a predetermined processing interval, and to output the generated position commands to the beam positioning system to operate the beam positioning system during the processing interval; A laser processing system comprising:

2. The system of claim 1 , wherein the at least one of the plurality of beam path components includes the scan lens.

3. The system of claim 1 , wherein the at least one of the plurality of beam path components includes the beam positioning system.

4. The system of claim 1 , wherein the controller is further configured to predict the thermal response of the at least one of the plurality of beam path components.

5. 5. The system of claim 4, wherein the controller is configured to predict the thermal response of the at least one of the plurality of beam path components based at least in part on laser power data corresponding to an amount of optical power or energy present in the at least one of the plurality of beam path components during the processing period.

6. 6. The system of claim 5, wherein the controller is configured to predict the thermal response of the at least one of the plurality of beam path components based at least in part on beam position data corresponding to a position of the beam path in the at least one of the plurality of beam path components during the processing period.

7. 6. The system of claim 5, wherein the controller is configured to predict the thermal response of the at least one of the plurality of beam path components based at least in part on preliminary position command beam position data corresponding to a position of the beam path at the at least one of the plurality of beam path components during the processing period.

8. The system of claim 1 , further comprising a beam modulator operative to attenuate the laser energy.

9. The system of claim 1 , further comprising a laser beam monitoring system operative to measure an optical quality of the laser energy beam and to generate sensor data representative of the measured optical quality.

10. The system of claim 9 , wherein the controller is configured to predict the thermal response of the at least one of the plurality of beam path components based at least in part on the sensor data.

11. The system of claim 1 , wherein the system does not include a temperature sensor configured to sense a temperature of the beam positioning system or the scan lens.

12. The system of claim 1 , further comprising at least one stage operative to provide relative movement between the beam waist and the workpiece in response to stage position commands.

13. The system of claim 12 , wherein the at least one stage is operable to move the workpiece.

14. The system of claim 12 , wherein the at least one stage is operative to move the scan lens.

15. 13. The system of claim 12, wherein the controller is communicatively coupled to the at least one stage beam positioning system, and the controller is configured to generate the stage position commands based at least in part on a predicted thermal response of at least one of the plurality of beam path components to the laser energy beam during the predetermined processing period, and to output the generated stage position commands to the at least one stage to operate the at least one stage during the processing period.

16. 1. A laser processing system for processing a workpiece, comprising: a laser source operative to output a beam of laser energy propagable along a beam path; a plurality of beam path components disposed in the beam path, a scan lens positioned to focus the beam laser energy deflected by the beam positioning system, thereby producing a focused beam of laser energy having a beam waist; a plurality of beam path components including: at least one stage operative to provide relative movement between said beam waist and said workpiece in response to stage position commands; a controller communicatively coupled to the at least one stage beam positioning system, the controller configured to generate the stage position commands based at least in part on a predicted thermal response of at least one of the plurality of beam path components to the laser energy beam during a predetermined processing interval, and to output the generated stage position commands to the at least one stage to operate the at least one stage during the processing interval; A laser processing system comprising:

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