Amplification compensation repeater for controlling image position

Abstract

And the amplification compensation repeater is used for controlling the image position. Embodiments are disclosed that are configured to optically relay laser energy beams propagating along an optical path to a scanning lens. In one embodiment, a system includes a first locator configured to move a scanning lens, and an optical repeater system configured to relay a beam path to an entrance pupil of the scanning lens. The optical repeater system includes an optical repeater having a first lens, a second lens, a first retro-reflector configured to direct a beam path to the optical repeater, a second retro-reflector, and a third retro-reflector, the second retro-reflector and the third retro-reflector located on opposite sides of the scanning lens. A second retroreflector and a third retroreflector may be located between the first lens and the second lens. The first retro-reflector is movable relative to the second retro-reflector and the third retro-reflector, and the first positioner is configured to move the scanning lens relative to the second retro-reflector.

Description

INTERACTION WITH RELATED APPLICATIONS

[0001] This application claims priority to U.S. Application No. 63 / 516,148, filed July 28, 2023, entitled “Magnification Compensation Relay for Controlling Image Position,” the contents of which are incorporated herein by reference TECHNICAL FIELD

[0002] Embodiments described herein generally relate to laser processing apparatuses, optical relay systems, components thereof, and techniques for operating the same. BACKGROUND

[0003] Laser processing systems or apparatuses are used in a wide variety of applications, including printed circuit board (PCB) fabrication, additive manufacturing, and the like. Many laser processing systems include a scan lens for focusing a beam of laser energy onto a workpiece, and a positioner for moving the focused beam of laser energy relative to the material to be processed. In some laser processing systems, the scan lens can move while the positioner remains stationary, so the optical path length between the scan lens and the positioner can change depending on the movement of the scan lens. Changes in the optical path length can cause the beam of laser energy to rotate about a pivot point that is located outside of the entrance pupil of the scan lens (also referred to herein as the “scan lens entrance pupil,” or more simply “SLEP”). The pivot point being located outside of the SLEP can result in telecentricity errors, beam distortion at the workpiece, and unwanted beam clipping at the scan lens entrance pupil due to galvanometer. SUMMARY

[0004] One embodiment of the present invention is a system comprising a scan lens, a first positioner configured to move the scan lens, and an optical relay system configured to relay a beam of laser energy propagating along a beam path to a scan lens entrance pupil. The optical relay system comprises an optical relay comprising a first lens and a second lens, a first retroreflector configured to direct the beam path of the beam of laser energy to the optical relay, a second retroreflector located on a first side of the scan lens, and a third retroreflector located on a second side of the scan lens. The second retroreflector and the third retroreflector can be located between the first lens and the second lens, wherein the first retroreflector is movable relative to the second retroreflector and the third retroreflector, and wherein the first positioner is configured to move the scan lens relative to the second retroreflector.

[0005] The foregoing system can further include a second positioner configured to deflect a beam path of the laser energy beam about a pivot point. An optical relay system is arranged and configured to relay the pivot point to the entrance pupil of the scan lens. The second positioner can be an Acousto-Optic Deflector (AOD) system or a galvanometer mirror system. In one embodiment, a longitudinal magnification of the optical relay system is between 0.81 and 0.25. In another embodiment, a longitudinal magnification of the optical relay system is between 0.64 and 0.36. In another embodiment, a longitudinal magnification of the optical relay system is between 0.56 and 0.42. In another embodiment, a longitudinal magnification of the optical relay system is between 0.51 and 0.47. In another embodiment, a longitudinal magnification of the optical relay system is 0.499. The first back reflector can be mounted on a linear stage configured to move the first back reflector relative to the optical relay. The first positioner can include the linear stage. The optical relay system can include a mirror configured to direct the beam path of the laser energy beam from the third back reflector to the scan lens. The optical relay system can further include a third positioner for deflecting the beam path of the laser beam, wherein the third positioner is coupled to the first positioner.

[0006] The present disclosure provides a system comprising: a first lens and a second lens, a first back reflector, a second back reflector, and a third back reflector. The first back reflector is disposed to receive a laser energy beam propagating along a beam path and is configured to direct the beam path to the first lens. The second back reflector is disposed to receive the laser energy beam from the first lens and direct the beam path to the third back reflector, and the third back reflector is disposed to receive the beam path from the second back reflector and is configured to direct the beam path to the second lens. The first back reflector is movable relative to the second back reflector and the third back reflector. The second back reflector and the third back reflector are fixed in position relative to each other. The system further comprises a structure, wherein the first lens and the second lens are fixed in position relative to each other and are fixed in position relative to the structure.

[0007] The system further comprises a structure and a positioner coupled to the structure, wherein the first back reflector is coupled to the positioner and is movable by the positioner. The system further comprises a mirror coupled to the positioner and arranged and configured to direct the beam path. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 A laser processing apparatus according to an embodiment is outlined.

[0009] Figure 2 and Figure 3 Various position states of a laser processing apparatus according to an embodiment are shown. DETAILED DESCRIPTION

[0010] Example embodiments are described herein with reference to the accompanying drawings. Unless otherwise expressly stated, the size, position, and / or shape of a component, feature, element, and / or the like in a drawing is not intended to be limiting. In the drawings, like or similar elements are designated with identical reference numbers throughout the several views. Accordingly, the same or similar elements can be described with reference to other drawings even if they are not explicitly mentioned in connection with each of the other drawings. Furthermore, elements that are not explicitly shown or described can be found in the other drawings.

[0011] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. A range of values, when stated, includes the upper and lower limits of the range, as well as any sub-ranges therebetween, unless otherwise stated. Unless otherwise stated, terms such as "first", "second", and / or the like are used to distinguish elements from one another, and are not otherwise intended to denote a particular order or sequence. For example, a node can be referred to as a "first node", and similarly, another node can be referred to as a "second node", or vice versa.

[0012] Unless specifically stated otherwise, the terms "about," "substantially," and the like are used as terms of approximation and / or estimation and not as terms of exactness. The use of such terms in describing the quantities, dimensions, formulas, parameters, and other quantities and characteristics are not meant to be exact, but allow for approximations, conversion factors, rounding off, measurement error, and the like, as well as other factors which those having ordinary skill in the art will readily recognize. Spatially relative terms, such as "under", "below", "lower", "over", "upper" and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if a device described is turned over in use, a

[0013] The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. It is recognized that various modifications, examples, and combinations are possible in the light of the disclosure and this application is intended to embrace all such modifications and changes as can come within the scope of the following claims. These examples and embodiments are provided to make the disclosure thoroughly and completely understood and to convey the scope of the disclosure to others of ordinary skill in the art. I. OVERVIEW

[0014] Figure 1 A laser processing apparatus according to embodiments of the present application is generally depicted.

[0015] Referring to the embodiments shown in Figure 1 A laser processing apparatus 100 (also simply referred to herein as "apparatus") for processing a workpiece 102 can be characterized as including a laser source 104 for generating a beam of laser energy, one or more positioners (e.g., a first positioner 106, a second positioner 108, a third positioner 110, a fourth positioner 130, a fifth positioner 140, or any combination thereof), and a scan lens 112, with reference to the embodiments shown in

[0016] Laser energy transmitted along beam path 114 through scan lens 112 propagates along beam axis 118 for delivery to workpiece 102. Laser energy propagating along beam axis 118 can be characterized as having a Gaussian-type spatial intensity profile, or a non-Gaussian (i.e., "shaped") spatial intensity profile (e.g., a "flat-top," a Gauss-Bessel type, or a Bessel type spatial intensity profile). Regardless of the type of spatial intensity profile, the spatial intensity profile can also be characterized as a shape (i.e., a cross-sectional shape, also referred to herein as a "spot shape") of the laser energy beam propagating along beam axis 118 (or beam path 114), which can be circular, elliptical, square, rectangular, triangular, hexagonal, annular, etc., or any arbitrary shape. As used herein, the term "spot size" refers to the diameter or maximum spatial width of a delivered laser energy beam (also referred to as a "process spot," a "spot position," or more simply a "spot") at a location where beam axis 118 intersects a region of workpiece 102 to be (at least partially) processed by the delivered laser energy beam. For purposes of discussion herein, spot size is measured as the radial or lateral distance from beam axis 118 to a point where optical intensity drops to 1 / e 2 of the optical intensity at beam axis 118. Generally, the spot size of the laser energy beam will be smallest at the beam waist. Once delivered to workpiece 102, laser energy within the beam can be characterized as having a spot size impacting workpiece 102 in a range from 2 μm to 200 μm. However, it will be recognized that the spot size can be made smaller than 2 μm, or larger than 200 μm.

[0017] Generally, the aforementioned positioners (e.g., first positioner 106, second positioner 108, third positioner 110, fourth positioner 130, and fifth positioner 140) are configured to vary the relative position between the spot and workpiece 102. It will be recognized, in view of the following description, that inclusion of second positioner 108 is optional, provided that apparatus 100 includes first positioner 106 and optional third positioner 110, fourth positioner 130, and fifth positioner 140. Likewise, it will be recognized that inclusion of third positioner 110 is optional, provided that apparatus 100 includes first positioner 106 and optional second positioner 108, fourth positioner 130, and fifth positioner 140. One of ordinary skill in the art will recognize that inclusion of any of the positioners is optional, provided that apparatus 100 includes a combination of the other positioners.

[0018] The apparatus 100 can also include one or more other optical components (e.g., beam collectors, beam expanders, beam shapers, beam splitters, apertures, filters, collimators, lenses, mirrors, prisms, polarizers, phase retarders, retro-reflectors, diffractive optical elements (commonly referred to in the art as DOEs), refractive optical elements (commonly referred to in the art as ROEs), or the like, or any combination thereof) to focus, expand, collimate, shape, polarize, filter, split, combine, trim, absorb, or otherwise modify, condition, direct, etc. the laser energy beam as it propagates along the beam path 114. With respect to optical components such as beam expanders, lenses, beam splitters, prisms, dichroic filters, windows, wave plates, DOEs, ROEs, etc. that are formed from bulk transparent material intended to transmit the incoming laser energy beam (which can optionally be coated with one or more anti-reflection coatings or the like), such optical components are generally referred to herein as "transmissive optical components." As used herein, a collection of positioners and other optical components can be considered to constitute a "beam path assembly" when assembled together in the laser processing apparatus 100. A. Laser source

[0019] In one embodiment, the laser source 104 is operable to generate laser pulses. In this regard, the laser source 104 can include a pulsed laser source, a CW laser source, a QCW laser source, a burst mode laser, or the like, or any combination thereof. In the case where the laser source 104 includes a QCW or CW laser source, the laser source 104 can be operated in a pulsed mode, or can be operated in a non-pulsed mode, but further includes a pulse gating unit (e.g., an acousto-optic (AO) modulator (AOM), a beam chopper, etc.) to temporally modulate the laser radiation beam output from the QCW or CW laser source. Although not depicted, the apparatus 100 can optionally include one or more harmonic generation crystals (also known as "wavelength conversion crystals") configured to convert the wavelength of light output by the laser source 104 to a separate wavelength. In another embodiment, however, the laser source 104 can be provided as a QCW laser source or a CW laser source, and does not include a pulse gating unit. Thus, the laser source 104 can be broadly characterized as being operable to generate a laser energy beam that can be represented as a series of laser pulses, or as a continuous or quasi-continuous laser beam, which can then be propagated along the beam path 114. Although many of the embodiments discussed herein refer to laser pulses, it should be appreciated that continuous or quasi-continuous beams can be substituted or additionally employed whenever appropriate or desired. B. First positioner

[0020] The first positioner 106 is configured, positioned, or otherwise disposed in the beam path 114 and is operable to diffract, reflect, refract, or the like, or any combination thereof, the laser pulses produced by the laser source 104 (i.e., "steer" the laser pulses) so as to steer or impart movement of the beam path 114 (e.g., relative to the scan lens 112), and thus, the beam axis 118 relative to the workpiece 102. Generally, the first positioner 106 is operable to impart movement of the beam axis 118 relative to the workpiece 102 along an X-axis (or direction), a Y-axis (or direction), or a combination thereof. Although not depicted, the Y-axis (or Y-direction) will be understood to refer to an axis (or direction) that is orthogonal to the illustrated X- and Z-axes (or directions).

[0021] Generally, the first positioner 106 can be disposed as a galvanometer mirror system, an AO deflector (AOD) system, an electro-optic (EO) deflector (EOD) system, a fast-steering mirror (FSM) system, or the like, or any combination thereof. An AOD of an AOD system generally includes an AO cell formed of a material such as crystalline germanium (Ge), gallium arsenide (GaAs), molybdenum lead oxide (PbMo04), tellurium dioxide (Te02), crystalline quartz, glassy Si02, arsenic trisulfide (As2S3), lithium niobate (LiNb03), or the like, or any combination thereof. An EOD of an EOD system generally includes an EO cell formed of lithium niobate, potassium tantalum niobate, or the like. Insofar as the AO and EO cells are configured to transmit an incident laser energy beam, the AO and EO cells can be considered to be of the type of transmissive optical members. C. Second Positioner

[0022] The second positioner 108 is disposed in the beam path 114 and is operable to diffract, reflect, refract, or the like, or any combination thereof, the laser pulses produced by the laser source 104 and passed through the first positioner 106 (i.e., "steer" the laser pulses) so as to steer or impart movement of the beam path 114 (e.g., relative to the scan lens 112), and thus, the beam axis 118 relative to the workpiece 102. Generally, the second positioner 108 is operable to impart movement of the beam axis 118 relative to the workpiece 102 along an X-axis (or direction), a Y-axis (or direction), or a combination thereof.

[0023] In view of the above, it should be appreciated that the second positioner 108 can be provided as a microelectromechanical system (MEMS) mirror or mirror array, an AOD system, an electro-optic deflector (EOD) system, a fast steering mirror (FSM) element (e.g., incorporating a piezoelectric actuator, an electrostrictive actuator, a voice coil actuator, etc.), a galvanometer mirror system, a resonant scanning mirror system, a rotating polygon scanner, or the like, or any combination thereof.

[0024] In one embodiment, the second positioner 108 can be provided as a biaxial galvanometer mirror system including two galvanometer mirror components, i.e., a first galvanometer mirror component (e.g., an X-axis galvanometer mirror component) configured to impart movement of the beam axis 118 relative to the workpiece 102 along an X-axis, and a second galvanometer mirror component (e.g., a Y-axis galvanometer mirror component) configured to impart movement of the beam axis 118 relative to the workpiece 102 along a Y-axis. However, in another embodiment, the second positioner 108 can be provided as a galvanometer mirror system including only a single galvanometer mirror component configured to impart movement of the beam axis 118 relative to the workpiece 102 along both the X-axis and the Y-axis. In still other embodiments, the second positioner 108 can be provided as a rotating polygon mirror system, etc. D. Third Positioner

[0025] In the illustrated embodiment, the third positioner 110 includes one or more linear stages (e.g., each capable of imparting translational movement of the workpiece 102 along an X, Y, and / or Z direction), one or more rotational stages (e.g., each capable of imparting rotational movement of the workpiece 102 about an axis parallel to an X, Y, and / or Z direction), or the like, or any combination thereof, arranged and configured to impart relative movement between the workpiece 102 and the scan lens 112, and thus between the workpiece 102 and the beam axis 118.

[0026] In view of the configurations described herein, it should be appreciated that movement of the process spot relative to the workpiece 102 (e.g., as imparted by the first positioner 106 and / or the second positioner 108) can be superimposed by any movement of the workpiece 102 or scan lens 112 as imparted by the third positioner 110. E. Fourth Positioner

[0027] Figure 2An apparatus 100 according to an embodiment of the present application is generally depicted along with a fourth positioner 130. In the illustrated embodiment, the fourth positioner 130 includes one or more linear stages configured to impart translational movement of the scan head 120 in the Z direction (e.g., to move the beam waist of the laser energy beam relative to the workpiece 102). The fourth positioner 130 includes a carriage 134 mounted on linear guides 132, which is mounted on a carriage 144 of the fifth positioner 140 (as described below).

[0028] With the configurations described herein, it should be appreciated that movement of the process spot relative to the workpiece 102 (e.g., as imparted by the first positioner 106 and / or the second positioner 108) can be superimposed by any movement of the scan head 120 as imparted by the fourth positioner 130. F. Fifth Positioner

[0029] Figure 2 An apparatus 100 according to an embodiment of the present application is generally depicted along with a fifth positioner 140. In the illustrated embodiment, the fifth positioner 140 includes one or more linear stages configured to impart relative movement between the fourth positioner 130 (including the scan head 120) and the workpiece 102 in the X direction (e.g., to move the process spot relative to the workpiece 102). The fifth positioner 140 includes a carriage 144 mounted on linear guides 142, which are fixed to a structure 300 of the apparatus 100 (e.g., such as a frame or a stand).

[0030] With the configurations described herein, it should be appreciated that movement of the process spot relative to the workpiece 102 (e.g., as imparted by the first positioner 106, the second positioner 108, and / or the fourth positioner 130) can be superimposed by any movement of the scan lens 112 as imparted by the fifth positioner 140. G. Scan Lens

[0031] The scan lens 112 (e.g., configured as a simple lens, or a compound lens) is generally configured to focus the laser energy beam directed along the beam path 114, typically to produce an optical waist that can be positioned at or near the desired process spot. The scan lens 112 can be configured as a non-telecentric f-0 lens (as shown), a telecentric f-0 lens, an axicon lens (in which case a series of optical waists are produced, which produces a number of process spots that are offset from one another along the beam axis 118), or the like, or any combination thereof. As noted above, in one embodiment, the scan lens 112 and the second positioner 108 are integrated into a common scan head 120. H. Controller

[0032] In general, the apparatus 100 includes one or more controllers (e.g., a controller 122) to control or facilitate control of the operation of the apparatus 100. In one embodiment, the controller 122 is communicatively coupled (e.g., through one or more wired or wireless, serial or parallel, communication links, such as USB, RS-232, Ethernet, Firewire, Wi-Fi, RFID, NFC, Bluetooth, Li-Fi, SERCOS, MARCO, EtherCAT, or the like, or any combination thereof) to one or more components of the apparatus 100, such as the laser source 104, the first positioner 106, the second positioner 108, the third positioner 110, the fourth positioner 130, the fifth positioner 140, the scan lens 112 (when configured as a variable focus lens), and the like, which can thus operate in response to one or more control signals output by the controller 122.

[0033] For example, the controller 122 can control operation of the first positioner 106, the second positioner 108, the third positioner 110, the fourth positioner 130, the fifth positioner 140, or any combination thereof, to impart relative movement between the beam axis 118 and the workpiece 102 so as to cause relative movement between the process spot and the workpiece 102 along a path or trajectory (also referred to herein as a "process trajectory") within the workpiece 102. It will be appreciated that any two, three, or four, or all five of the positioners can be controlled so that the positioners impart relative movement between the process spot and the workpiece 102 simultaneously (thereby imparting "compound relative movement" between the beam axis and the workpiece). Of course, it is possible to control only one positioner (e.g., the first positioner 106, the second positioner 108, the third positioner 110, the fourth positioner 130, or the fifth positioner 140) at any time to impart relative movement between the process spot and the workpiece 102 (thereby imparting "non-compound relative movement" between the beam axis and the workpiece).

[0034] In general, the controller 122 includes one or more processors that are operable to generate the aforementioned control signals upon execution of instructions. The processors can be provided as programmable processors (e.g., including one or more general purpose computer processors, microprocessors, digital signal processors, or the like, or any combination thereof) that are operable to execute instructions. The instructions that can be executed by the processors can be implemented as software, firmware, or the like, or implemented with any suitable 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, analog, and mixed analog / digital circuits - or the like, or any combination thereof. Execution of the instructions can be performed on the processors, distributed among the processors, made parallel across processors within a device or across devices over a network, or the like, or any combination thereof.

[0035] In one embodiment, the controller 122 includes a tangible medium, such as a computer memory, that is accessible to 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, magnetic hard disk, etc.), optical discs, volatile or non-volatile semiconductor memory (e.g., RAM, ROM, NAND-type flash memory, NOR-type flash memory, SONOS memory, etc.), and the like, and can be accessed locally, remotely (e.g., across a network), or a combination thereof. In general, the instructions can be stored as computer software (e.g., executable code, files, instructions, etc., library files, etc.), which can be readily written by a skilled artisan from the teachings provided herein, such as in C, C++, Visual Basic, Java, Python, Tel, Perl, Scheme, Ruby, a combination language, a hardware description language (e.g., VHDL, VERILOG, etc.), etc. The computer software is typically stored in one or more data structures that are communicated by the computer memory.

[0036] Although not shown, one or more drivers (e.g., RF drivers, servo drivers, line drivers, power supplies, etc.) can be communicatively coupled to inputs of one or more of the components, such as the laser source 104, the first positioner 106, the second positioner 108, the third positioner 110, the fourth positioner 130, the fifth positioner 140, and the scan lens 112 (when configured as a zoom lens), etc., for controlling such components. Thus, as is known in the art, one or more of the components, such as the laser source 104, the first positioner 106, the second positioner 108, the third positioner 110, the fourth positioner 130, the fifth positioner 140, and the scan lens 112 (when configured as a zoom lens), etc., can be considered to also include any appropriate drivers. Each of such drivers will typically include an input that is communicatively coupled to the controller 122, and the controller 122 is operable to generate one or more control signals (e.g., trigger signals, etc.) that can be sent to the input of the one or more drivers associated with one or more components of the apparatus 100. The components, such as the laser source 104, the first positioner 106, the second positioner 108, the third positioner 110, the fourth positioner 130, the fifth positioner 140, and the scan lens 112 (when configured as a zoom lens), etc., are thus responsive to the control signals generated by the controller 122.

[0037] Although not shown, one or more additional controllers (e.g., component-specific controllers) can optionally be communicatively coupled to inputs of drivers that are communicatively coupled to components (and thus associated with the components), such as the laser source 104, the first positioner 106, the second positioner 108, the third positioner 110, the fourth positioner 130, the fifth positioner 140, and the scan lens 112 (when configured as a zoom lens), etc. In such an embodiment, each component-specific controller can be communicatively coupled to the controller 122 and operable to generate one or more control signals (e.g., trigger signals, etc.) in response to one or more control signals received from the controller 122, which can then be sent to inputs of drivers to which the component-specific controller is communicatively coupled. In such an embodiment, the component-specific controllers can operate similarly as described with respect to the controller 122.

[0038] In another embodiment in which one or more component-specific controllers are provided, a component-specific controller associated with a component (e.g., the laser source 104) can be communicatively coupled to a component-specific controller associated with a component (e.g., the first positioner 106, etc.). In such an embodiment, one or more of the component-specific controllers can operate to generate one or more control signals (e.g., trigger signals, etc.) in response to one or more control signals received from one or more other component-specific controllers. II. Embodiments to address positioning errors of pivot points relative to the SLEP

[0039] In certain embodiments of the apparatus 100, when the scan lens 112 is moved while the first positioner 106 is maintained stationary, an optical path length between the first positioner 106 and an entrance pupil of the scan lens 112 can change as a function of movement of the scan lens 112.

[0040] In embodiments where the scan lens is mounted to an X stage (e.g., the fifth positioner 140), the X stage moves the scan head 120 along an X axis, the pivot point can be offset relative to the entrance pupil, which results in a telecentricity error of the beam path 114, causing an error in the position of the process spot on the workpiece 102. In addition, in some embodiments, the first positioner 106 can be configured as a pair of AODs that are capable of increased deflection range of the beam path 114 relative to AODs of the prior art. For example, in such embodiments where the second positioner 108 is configured as a pair of galvanometer mirrors, when the pivot point is offset from the entrance pupil (due to the X direction movement of the scan lens 112 changing the optical path length), the increased range of deflection of the beam path 114 can cause the beam path 114 to miss the galvanometer mirrors at or near the farthest range of beam path deflection. One solution to this problem is to increase the size of the galvanometer mirrors. However, because the galvanometer mirrors undergo very high acceleration during operation, the additional mass of larger mirrors can contribute to the wobble of the mirrors, which can detrimentally affect the positioning accuracy of the process spot on the workpiece 102.

[0041] In the following, exemplary embodiments of an optical relay system are discussed that are operable to compensate for the increase in optical path length caused by the movement of the scan lens 112 relative to the first positioner 106 to ensure that the laser energy beam 116 propagating along the beam path 114 is rotated about the pivot point located at or at least near the entrance pupil of the scan lens 112, so that the beam path 114 does not miss the galvanometer mirrors.

[0042] In general, an optical relay with a fixed magnification of M = 1 is used to image an object (e.g., the deflection pivot point of the AOD) to a new plane (e.g., the image plane located at the entrance pupil of the scan lens), for example, to ensure proper telecentricity of the beam path 114 at the workpiece 102. Such a relay is generally fixed relative to the first positioner 106 and the scan lens 112. However, if the scan lens 112 is moved relative to the first positioner 106 and relative to the fixed relay with a magnification of 1, the pivot point will move relative to the scan lens 112, which results in an offset of the pivot point relative to the entrance pupil of the scan lens.

[0043] Figure 2A view showing an overview of an embodiment of the apparatus 100 in a first position state. In this embodiment, the apparatus 100 includes an optical relay system 200 that is operable to automatically position the pivot point 124 at the entrance pupil 126 of the scan lens during movement of the scan head 120 along the X axis relative to the first positioner 106. The apparatus 100 includes the first positioner 106, the second positioner 108, the fourth positioner 130, the fifth positioner 140, and the optical relay system 200. The first positioner 106 directs the laser energy beam 116 (e.g., its overview is depicted as an arrow) along the beam path 114. The apparatus 100 further includes a structure 300 (e.g., such as a frame or a stand) that includes two structural portions 302 (e.g., portions of the frame or stand, or another structure such as an optical wall). The fifth positioner 140 includes a rail 142 mounted to the structure 300, and a carriage 144 configured to move along the rail 142 along the X axis. A fold mirror 212 configured to direct the beam path 114 from the optical relay system 200 to the scan head 120 is also mounted on the carriage 144. The fourth positioner 130 is mounted to the carriage 144, and is operable to move the scan head 120 (including the second positioner 108 and the scan lens 112 having the entrance pupil 126) along the Z axis as necessary to set the beam waist relative to the workpiece 102. In this embodiment, for the purpose of illustration of the present invention, the fifth positioner 140 is positioned such that the beam path 114 of the laser energy beam 116 intersecting the workpiece 102 is any distance XI = 110 mm from the first positioner 106 in the position state shown in Figure 2

[0044] ​The optical relay system 200 includes an optical relay 201 configured in optical communication with the first positioner 106. In this embodiment, the optical relay 201 includes a first lens 202 mounted on one of the structure sections 302 and a second lens 204. The optical relay system 200 further includes a first return reflector 206, a second return reflector 208, and a third return reflector 210. The first return reflector 206 includes a first mirror 206a and a second mirror 206b. The second return reflector 208 is mounted on one of the structure sections 302 and includes a first folding mirror 208a and a second folding mirror 208b. The third return reflector 210 is mounted on another one of the structure sections 302 and includes a first folding mirror 210a and a second folding mirror 210b. The first return reflector 206 and the folding mirror 212 are mounted on the carriage 144, which can then be moved along the X-axis relative to the first positioner 106, the second return reflector 208, the third return reflector 210, and the optical relay 201 by the fifth positioner 140 (e.g., in response to one or more commands output by the controller 122). In another embodiment, the first return reflector 206 and the folding mirror 212 can be mounted to a secondary stage (not shown) instead of the fifth positioner 140.

[0045] As noted above, the optical relay is used to image the object (e.g., the pivot point of the deflection of the AOD) to a new plane (the image plane of the entrance pupil 126 of the scan lens) at a lateral magnification M. If the object distance in Z (the direction of light propagation) changes, the image distance in Z also changes, but by the square of the lateral magnification M times the change in object distance. Typically, the beam axis 114 is aligned to the stage so that the beam propagates parallel to the stage travel, and the optical path length changes, but the beam nominally does not move over the optical elements mounted on the stage. This means that in the coordinate system of the stage, the main thing that changes as the stage moves through the full range of travel is the image position (the pivot point of the deflection) moves in the direction that the laser energy beam 116 propagates (and the direction that the stage travels, since they are parallel).

[0046] The optical repeater system 200 operates by guiding the beam path 114 to the first retroreflector 206, which then guides the beam path 114 back in the opposite direction to the optical repeater 201. Because the beam path is folded, the change in the object distance (from the AOD to the optical repeater 201) is twice the movement of the scanning head 120 on the fifth positioner 140. In this embodiment, the optical repeater 201 is designed to have a lateral magnification set at M = sqrt(2) / 2 = 0.707. This lateral magnification produces M 2 A magnification of 0.5 is used to change the image distance (the distance from the optical repeater 201 to the pivot point 124) to be exactly the amount of movement of the beam path 114 relative to the workpiece 102 (e.g., as the fifth positioner 140 moves the scanning head 120 along the X-axis), thereby maintaining the position of the pivot point 124 at the entrance pupil 126 of the scanning lens.

[0047] Figure 3 exhibit Figure 2 The diagram shows a schematic view of an embodiment of the device 100 in a second position state, wherein the fifth positioner 140 has moved the scanning head 120 (and the optical path 114 incident on the workpiece 102) to a distance X from the first positioner 106. 2 At a distance of 160mm, that is, a change of 50mm in the X direction. Because the first retroreflector 206 is mounted on the bracket 144, and after receiving the laser energy beam 116 from the first locator 106, it guides the laser energy beam 116 propagating along the beam path 114 back toward the optical repeater 201, the object distance ΔO (the distance between the first locator 106 and the optical repeater 201) increases by 100mm. In this embodiment, because the optical repeater 201 has a lateral magnification set at M=0.707 (this produces M... 2 =0.5 vertical magnification). The change in the image distance ΔI (the change in distance between the optical repeater 201 and the entrance pupil 126) is half the change in the object distance (M). 2 ∙ΔO). In this embodiment, this causes the image distance to move by 0.5∙100=50mm in the X direction, the same amount as the change in position of the scanning head 120 mounted on the fifth locator 140, thereby maintaining the position of the pivot point 124 in the entrance pupil 126.

[0048] Although the horizontal magnification of M = sqrt(2) / 2 (which produces M) 2= 0.5 in combination with folding the beam path to double the change in the object distance as the scan head 120 moves in the X direction results in the pivot point 124 being located at the entrance pupil 126, but in other embodiments the optical relay 201 can be designed to have a longitudinal magnification M that is not equal to 0.5 2 While these settings of the lateral magnification can not be optimal for maintaining the pivot point 124 at the location of the entrance pupil 126, such settings of the magnification can be selected for other reasons (e.g., to achieve a particular beam diameter at the process spot). Thus, in various embodiments the optical relay 201 can be provided with a lateral magnification M such that the longitudinal magnification M of the optical relay 201 is between about 0.81 and about 0.25, between 0.64 and about 0.36, between about 0.56 and about 0.42, or between about 0.51 and about 0.47. 2 In another embodiment, the longitudinal magnification of the optical relay 201 is about 0.499. In other embodiments, the optical relay 201 can have a variable focus that can be set manually by an operator or set by the controller 122. III. CONCLUSION

[0049] The foregoing is a description of embodiments and examples of the invention and should not be construed as limiting. While some specific embodiments and examples have been described with reference to the figures, one of ordinary skill in the art will readily appreciate that many modifications to the disclosed embodiments and examples are possible without materially departing from the novel teachings and advantages of the invention. Accordingly, all such modifications are intended to be included within the scope of the invention as defined by the following claims. For example, one of ordinary skill in the art will readily comprehend that the subject matter of any sentence, paragraph, example or embodiment can be combined with the subject matter of any other sentence, paragraph, example or embodiment unless such a combination is mutually exclusive. Thus, the scope of the present invention should be determined by the following claims and equivalents thereof.

Claims

1. A system comprising: a scan lens; a first positioner configured to move the scan lens; and an optical relay system configured to relay a laser energy beam propagating along a beam path of the laser energy beam to an entrance pupil of the scan lens, wherein the optical relay system includes: an optical relay including a first lens and a second lens; a first back reflector configured to direct the beam path of the laser energy beam to the optical relay; and a second back reflector positioned on a first side of the scan lens; and a third back reflector positioned on a second side of the scan lens, wherein the second back reflector and the third back reflector are positioned between the first lens and the second lens, wherein the first back reflector is movable relative to at least one selected from the group consisting of the second back reflector and the third back reflector, wherein the first positioner is configured to move the scan lens relative to the second back reflector and the third back reflector.

2. The system of claim 1, further comprising a second positioner configured to deflect the beam path of the laser energy beam about a pivot point.

3. The system of claim 2, wherein the optical relay system is arranged and configured to relay the pivot point to the entrance pupil of the scan lens.

4. The system of claim 2, wherein the second positioner is at least one selected from the group consisting of an acousto-optic deflector system and a galvanometer mirror system.

5. The system of claim 1, wherein the optical relay has a longitudinal magnification between 0.81 and 0.

25.

6. The system of claim 5, wherein the optical relay has a longitudinal magnification between 0.64 and 0.

36.

7. The system of claim 6, wherein the optical relay has a longitudinal magnification between 0.56 and 0.

42.

8. The system of claim 7, wherein the optical relay has a longitudinal magnification between 0.51 and 0.

47.

9. The system of claim 8, wherein the optical relay has a longitudinal magnification of 0.

499.

10. The system of claim 1, wherein the first back reflector is mounted on a linear stage configured to move the first back reflector relative to the optical relay.

11. The system of claim 10, wherein the first positioner includes the linear stage.

12. The system of claim 1, wherein the optical relay system includes a mirror configured to direct the beam path of the laser energy beam from the third back reflector to the scan lens.

13. The system of claim 1, further comprising a third positioner configured to deflect the beam path of the laser energy beam, wherein the third positioner is coupled to the first positioner.

14. A system comprising: a first lens and a second lens; and a first back reflector, a second back reflector, and a third back reflector, wherein: ​ ​ ​ the first retro-reflector is arranged to receive a laser energy beam propagating along a beam path, and is configured to direct the beam path to the first lens, the second retro-reflector is configured to receive the laser energy beam from the first lens, and is configured to direct the beam path to the third retro-reflector, and the third retro-reflector is configured to receive the beam path from the second retro-reflector, and is configured to direct the beam path to the second lens, wherein the first retro-reflector is movable relative to at least one selected from the group consisting of the second retro-reflector and the third retro-reflector.

15. The system of claim 14, wherein the second retro-reflector and the third retro-reflector are fixed in position relative to each other.

16. The system of claim 14, further comprising a structure, wherein the first lens and the second lens are fixed in position relative to each other.

17. The system of claim 14, further comprising: a structure; and a positioner coupled to the structure, wherein the first retro-reflector is coupled to the positioner and is movable by the positioner.

18. The system of claim 17, further comprising a mirror coupled to the positioner and arranged and configured to direct the beam path. ​

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