Systems and methods for thermally stable operation of acousto-optic deflectors with reduced acoustic intelligence

Abstract

A system is provided that includes an acousto-optic deflector (AOD) scanning system for deflecting a beam path and a controller for controlling the AOD scanning system. The controller may control operation of one driver of the AOD scanning system to deflect the beam path from a first position to a second position, and may control operation of another driver of the AOD scanning system to reduce transmission of laser energy in the deflected beam path during a period of time, wherein the period ends when operation of one of the first driver or the second driver is controlled to deflect the beam path from the first position to the second position.

Description

Technical Field

[0001] The specific examples of this invention generally relate to acousto-optic deflectors, laser processing equipment with acousto-optic deflectors, and their operating techniques. Background Technology

[0002] Referring to Figure 1, a laser processing apparatus 100 operable to process a workpiece 102 (e.g., to form one or more features, such as through-holes, slots, holes, grooves, gaskets, or the like or any combination thereof) typically includes a laser source 104, a positioner 106, and a scanning lens 108, as well as other components. The apparatus will also typically include a controller 110 operable to control the operation of the laser source 104 and the positioner 106. The positioner 106 is operable to reflect, refract, and / or diffract the laser energy beam to deflect the beam path 112, the laser energy in the beam traveling along the beam path as it propagates from the laser source 104 to the scanning lens 108. The laser energy deflected to the scanning lens 108 is focused by the scanning lens 108 and transmitted to the workpiece 102 such that the beam waist of the focused laser energy beam is located at or near the workpiece 102.

[0003] To achieve extremely rapid deflection of the beam path 112 relative to the workpiece 102 in two dimensions (e.g., along the X and Y axes, with the Y axis orthogonal to the plotted X and Z axes), the positioner 106 may include a galvanometer mirror scanning system and an acousto-optic deflector (AOD) scanning system optically configured "upstream" of the galvanometer mirror scanning system. The galvanometer mirror scanning system typically includes a pair of galvanometer mirrors optically connected in series (e.g., one galvanometer mirror operable to deflect the beam path 112 along the X-axis and the other galvanometer mirror operable to deflect the beam path 112 along the Y-axis). The AOD scanning system typically includes a pair of acousto-optic deflectors (AODs) optically connected in series. For example, and referring to FIG2, the AOD scanning system may include a first AOD 200 configured to deflect the beam path 112 along the X-axis, and a second AOD 202 configured to deflect the beam path 112 along the Y-axis.

[0004] Those skilled in the art will recognize that the AOD utilizes the diffraction effect caused by one or more acoustic waves propagating through the AO unit to diffract incident light waves (i.e., a laser energy beam in the context of this application) simultaneously propagating through the AO unit. After driving the AOD to diffract the incident laser energy beam, a diffraction pattern is generated, which typically includes zero-order and first-order diffraction peaks, and may also include other higher-order diffraction peaks (e.g., second-order, third-order, etc.). Typically, the amount of optical power diffracted into the first-order diffraction peak (e.g., compared to the zero-order diffraction peak) is determined by the manner in which the AOD is driven to diffract the incident laser energy beam. As known in the art, the portion of the diffracted laser energy beam in the zero-order diffraction peak is referred to as the "zero-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 on. Typically, the zero-order beam and other diffraction-order beams (e.g., the first-order beam) propagate along different beam paths after leaving the AO unit (e.g., through the optical output side of the AO unit). For example, a zero-order beam propagates along a zero-order beam path, a first-order beam propagates along a first-order beam path, and so on.

[0005] In Figure 2, the zero-order beam path of the first AOD 200 is identified by 204, and the zero-order beam path of the second AOD 202 is identified by 206. Similarly, the first-order beam paths of the first AOD 200 and the second AOD 202 are each identified by 112. Furthermore, the locator 106 shown in Figure 2 includes one or more optical components (e.g., one or more mirrors, lenses, etc., generally identified by 208) configured to relay the zero-order beam path 204 and the first-order beam path 112 of the first AOD 200 to the second AOD 202. The locator 106 shown in Figure 2 also includes a beam trap 210 configured to intercept (e.g., block, absorb, etc.) laser energy propagating along the zero-order beam path 206 (and laser energy propagating along second-order or higher-order beam paths), but not laser energy propagating along the first-order beam path 112.

[0006] The AO unit of the AOD absorbs a certain amount of laser energy beam propagating through the unit. If the laser energy beam is high enough in power, the absorbed energy can locally heat the material forming the AO unit and induce thermal lensing within the AO unit. Thermal lensing can cause the wavefront of the laser energy beam propagating along beam path 112 to focus, defocus, or otherwise distort. Thermal lensing within the AO unit is not necessarily bad. If the laser energy beam propagating to the AO unit is sufficiently stationary and the power in the laser energy beam is relatively constant (or varies periodically or otherwise predictably), the wavefront distortion effects (e.g., focusing, defocusing, or other wavefront distortions, as noted above) caused by the thermal gradient within the AO unit can be considered to be “stable” over time and can generally be compensated for to ensure that workpiece 102 is satisfactorily processed. However, if the laser energy beam propagating to the AO unit is not sufficiently stationary, or if the power in the laser energy beam is not sufficiently constant or unpredictable, or if the spatial power distribution of the laser energy incident on the AO unit changes significantly, the wavefront distortion effect caused by the thermal gradient within the AO unit becomes unstable and extremely difficult to compensate for to ensure that the workpiece 102 is satisfactorily processed.

[0007] For example, in the context of the positioner 106 shown in Figure 2, the optical component 208 ensures that the optical power incident on the AO unit of the second AOD 202 is substantially constant. However, the position of the zero-order beam path 204 incident on the AO unit of the second AOD 202 can change slightly over time, and the optical power in the zero-order beam path 204 can vary depending on the deflection of the first-order beam path 112 given by the first AOD 200. Therefore, the thermal gradient within the AO unit of the second AOD 202 may not be sufficiently constant or static. Such instabilities in the thermal gradient within the AO unit of the second AOD 202 may adversely produce an asymmetric energy distribution around the optical axis of the laser energy beam ultimately delivered to the workpiece 102, and degrade the ability of the second AOD 202 (and thus the AOD scanning system with the second AOD) to accurately deflect the beam path 112 to the desired position relative to the workpiece 102, and degrade the ability of the AOD scanning system to ensure that the beam waist is ideally positioned at or near the workpiece 102. Summary of the Invention

[0008] One specific embodiment of the present invention can be broadly characterized as a system comprising an acousto-optic deflector (AOD) scanning system operable to deflect a beam path from which a laser energy beam propagates. The AOD scanning system may include: a first acousto-optic deflector (AOD) configured and operable in response to a first drive signal to deflect the beam path along a first axis; a second AOD configured and operable in response to a second drive signal to deflect the beam path deflected by the first AOD along a second axis; a first driver connected to the first AOD and operable to generate the first drive signal; a second driver connected to the second AOD and operable to generate the second drive signal; and a controller connected to the first driver and the second driver and operable to control the operation of the first driver and the second driver. The controller is operable to control an operation of one of the first driver or the second driver to deflect the beam path from a first position to a second position. The controller can also be operated to control the operation of the other of the first driver or the second driver to reduce the transmission of laser energy in the deflected beam path during a period of time. Typically, the period ends when the beam path deflects from the first position to the second position (or approximately when the beam path deflects from the first position to the second position).

[0009] Another specific embodiment of the invention can be broadly characterized as a controller for use with an acoustic optical deflector (AOD) scanning system. For example, the controller may include at least one processor and a memory accessible by the at least one processor. For example, the memory may store instructions thereon that, when executed by the at least one processor, cause the controller to control an operation of the AOD scanning system to: a) control an operation of one driver of the AOD scanning system to deflect a beam path from a first position to a second position, and b) control an operation of another driver of the AOD scanning system to reduce a transmission of laser energy in the deflected beam path by an AOD connected thereto during a time period. Typically, the time period ends when the beam path deflects from the first position to the second position (or approximately when the beam path deflects from the first position to the second position).

[0010] Another specific embodiment of the invention can be broadly characterized as a non-transitory computer-readable medium for use with a controller capable of controlling an acoustic optical deflector (AOD) scanning system. The non-transitory computer-readable medium may specifically implement instructions that, when executed by the controller, cause the controller to: a) control an operation of a driver of the AOD scanning system to deflect a beam path from a first position to a second position, and b) control an operation of another driver of the AOD scanning system to reduce a transmission of laser energy in the deflected beam path by an AOD connected thereto during a time period. Typically, the time period ends when the beam path deflects from the first position to the second position (or approximately when the beam path deflects from the first position to the second position). Attached Figure Description

[0011] Figure 1 schematically illustrates a laser processing apparatus of the related art, wherein a positioner according to a specific embodiment of the present invention can be incorporated into the laser processing apparatus and operates according to a specific embodiment of the present invention.

[0012] Figure 2 schematically illustrates a locator based on relevant technologies.

[0013] Figure 3 A locator according to a specific embodiment of the present invention is schematically illustrated.

[0014] Figure 4 A diagram illustrating a specific example of a control according to the present invention. Figure 3 The timing diagram of AOD in the AOD scanning system shown in the figure. Detailed Implementation

[0015] This document describes exemplary specific examples with reference to the accompanying drawings. Unless otherwise expressly stated, the size, position, etc., of components, features, elements, etc., and any distances between components, features, elements, etc., in the drawings are not necessarily drawn to scale, but are exaggerated for clarity.

[0016] The terminology used herein is for the purpose of describing specific, exemplary instances only and is not intended to be restrictive. As used herein, unless the context explicitly indicates otherwise, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well. It should be understood that the terms “comprises” and / or “comprising,” when used in this specification, designate the presence of stated features, integrals, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof. Unless otherwise specified, when describing a range of values, the range includes both the upper and lower limits of the range, and any subranges therein. Unless otherwise indicated, terms such as “first,” “second,” etc., are used only to distinguish one element from another. For example, a 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 are for organizational purposes only and should not be considered as limiting the subject matter described.

[0017] Unless otherwise indicated, the terms “about,” “approximately,” “substantially,” etc., mean that quantities, sizes, formulations, parameters, and other quantities and characteristics are not and need not be precise, but may be approximate and / or larger or smaller as required, thereby reflecting tolerances, conversion factors, rounding, measurement errors and the like, and other factors known to those skilled in the art.

[0018] Spatial relative terms such as “below,” “under,” “lower,” “above,” and “upper,” and similar terms, may be used herein for ease of description to describe the relationship of one element or feature to another, as illustrated in the figures. It should be understood that spatial relative terms are intended to encompass different orientations other than those depicted in the figures. For example, if the objects in the figures are flipped, the element described as “below” or “under” other elements or features will then be oriented “above” other elements or features. Thus, the illustrative term “below” may encompass both the orientations of “above” and “below.” Objects may be oriented in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein may be interpreted accordingly.

[0019] The same numbering throughout the text refers to the same component. Therefore, other diagrams can be consulted to describe the same or similar numbers, even if these numbers are neither mentioned nor described in the corresponding diagrams. Furthermore, even components not represented by reference numbers can be described by referring to other diagrams.

[0020] It should be understood that many different forms and specific examples are possible without departing from the spirit and teaching of this disclosure, and therefore this disclosure should not be considered as limited to the exemplary specific examples set forth herein. Rather, such examples and specific examples are provided so that this disclosure will be thorough and complete, and will convey the scope of this disclosure to those skilled in the art.

[0021] I. General Discussion on Positioners

[0022] According to a specific embodiment of the present invention, an AOD scanning system in the locator 106 described above with respect to FIG1 can be provided, such as Figure 3 The example shown is (i.e., as an AOD scanning system 300).

[0023] See Figure 3 The AOD scanning system 300 includes a first AOD 302 configured to deflect the beam path 112 along a first axis (e.g., the aforementioned X-axis), and a second AOD 304 configured to deflect the beam path 112 along a second axis orthogonal to the first axis (e.g., the aforementioned Y-axis). Figure 3 In the first AOD 302, the zero-order beam path is identified by 306, and the zero-order beam path of the second AOD 304 is identified by 308. Similarly, the first-order beam path of the first AOD 302 is identified as 112', and the first-order beam path of the second AOD 304 is identified as 112"". It should be understood that each of the first-order beam path 112' and the first-order beam path 112" represents a specific example of the beam path along which the laser energy beam can propagate (e.g., propagate to the scanning lens 108); therefore, each of the beam path 112' and the beam path 112" can also be generally referred to herein as "beam path 112", and thus, the first AOD 302 is configured and configured such that the first-order beam path 112' is deflected along the first axis of the AOD scanning system 300, and the second AOD 304 is configured and configured such that the first-order beam path 112" is deflected along the second axis of the AOD scanning system 300. An optical relay system 305 is disposed between a first AOD 302 and a second AOD 304 such that the pivot point of the first AOD 302 (i.e., located within the AO cell of the first AOD 302) is imaged at the pivot point of the second AOD 304 (i.e., located within the AO cell of the second AOD 304), as is known in the art.

[0024] also, Figure 3The AOD scanning system 300 shown includes: a first beam trap 310 configured to intercept laser energy propagating along a zero-order beam path 306 (and laser energy propagating along a second-order or higher-order beam path), but not to intercept laser energy propagating along a first-order beam path 112'; and a second beam trap 312 configured to intercept laser energy propagating along a zero-order beam path 308 (and laser energy propagating along a second-order or higher-order beam path), but not to intercept laser energy propagating along a first-order beam path 112'. Energy; and a third beam trap 314 (also referred to herein as a “moving beam trap”), configured and configurable to intercept laser energy propagating along a first-order beam path 112” to which it is selectively deflected (e.g., as indicated by arrow 315, and described in more detail below). Although not shown, a galvanometer mirror scanning system (e.g., comprising a pair of galvanometer mirrors configured and configurable to deflect the laser energy beam along two axes, as known in the art) may be located optically downstream of the second AOD 304 and upstream of the scanning lens 108 in the beam path 112”.

[0025] Typically, the AO units of each of the first AOD 302 and the second AOD 304 are formed of a material susceptible to thermal lensing (e.g., as described above) in the presence of a laser energy beam with sufficiently high optical power propagating along the beam path 112. For example, the AO units of each of the first AOD 302 and the second AOD 304 may be formed of crystalline germanium. In this example, the laser energy beam propagating along the beam path 112 will have a wavelength in the range of 2 μm (or about 2 μm) to 20 μm (or about 20 μm) and a sufficiently high average power (e.g., greater than or equal to 150 W, or about 150 W) to induce thermal lensing within the AO units of the first AOD 302 and the second AOD 304. In this configuration, the laser energy beam can be generated by a laser source (e.g., laser source 104), which is provided, for example, a suitable high-power carbon dioxide or carbon monoxide gas laser. Typically, the high-power carbon dioxide or carbon monoxide gas laser is configured to generate a continuous wave (CW) or quasi-CW (QCW) laser energy beam, or to generate a laser energy beam comprising discrete pulses (typically tens of microseconds or longer in duration).

[0026] Although not shown, each of the first AOD 302 and the second AOD 304 includes at least one transducer attached to its AO unit. Typically, the transducer is a piezoelectric transducer operable to vibrate in response to an externally applied RF signal (i.e., a drive signal). The transducer is attached to the AO unit of the AOD such that the vibrating transducer generates a corresponding acoustic wave propagating within the AO unit. Those skilled in the art will understand that the amplitude, frequency, and duration of the acoustic wave correspond to the amplitude and frequency of the RF power in the applied drive signal, and the duration of the applied drive signal itself.

[0027] A drive signal can be applied to the input of a transducer by an associated RF driver. Therefore, the AOD scanning system 300 may, for example, include a first RF driver 316 electrically connected to each transducer of the first AOD 302, and a second RF driver 318 electrically connected to each transducer of the second AOD 304. Typically, each of the RF drivers 316 and 318 may include an RF synthesizer, an amplifier coupled to the output of the RF synthesizer, and an impedance matching circuit coupled to the output of the amplifier. The RF synthesizer (e.g., a DDS synthesizer) generates and outputs a preliminary signal having a desired frequency; the amplifier amplifies the preliminary signal to the desired amplitude, thereby converting the preliminary signal into a drive signal; and the drive signal is applied to the input of the transducer via the impedance matching circuit.

[0028] The operation of the first RF driver 316 and the second RF driver 318 can be controlled in response to a command signal output by a controller (e.g., controller 320) to generate drive signals with different frequencies and amplitudes, which can be rapidly applied to the transducers of their respective AODs. Typically, the rates at which different drive signals can be applied to the transducers of the AOD can be greater than, equal to, or less than 8kHz, 10kHz, 20kHz, 30kHz, 40kHz, 50kHz, 75kHz, 80kHz, 100kHz, 250kHz, 500kHz, 750kHz, 1MHz, 5MHz, 10MHz, 20MHz, 40MHz, 50MHz, 75MHz, 100MHz, 125MHz, 150MHz, 175MHz, 200MHz, 225MHz, 250MHz, etc., or between any of these values. Therefore, the duration of any drive signal applied to the transducer of the AOD can be greater than, equal to or less than 200μs, 125μs, 100μs, 50μs, 33μs, 25μs, 20μs, 15μs, 13.3μs, 12.5μs, 10μs, 4μs, 2μs, 1.3μs, 1μs, 0.2μs, 0.1μs, 0.05μs, 0.025μs, 0.02μs, 0.013μs, 0.01μs, 0.008μs, 0.0067μs, 0.0057μs, 0.0044μs, 0.004μs, etc., or between any of these values. The controller 320 will therefore replace the controller 110 shown in FIG1, and can control the operation of the laser source 104 in addition to controlling the operation of any other scanning system (such as the aforementioned galvanometer mirror scanning system) of the AOD scanning system 300 and the positioner 106.

[0029] For the purposes of this disclosure, the action of applying a drive signal to the transducer of the AOD is also referred to herein as “driving” the AOD. Therefore, when the first AOD 302 is driven by a drive signal applied from the first RF driver 316, a portion of the laser energy incident on the AO unit of the first AOD 302 is diffracted to propagate along its first-order beam path 112' to the AO unit of the second AOD 304, and another portion of the incident laser energy propagates along the zero-order beam path 306. If no drive signal is applied from the first RF driver 316, the laser energy incident on the AO unit of the first AOD 302 propagates only along the zero-order beam path 306. Similarly, when the second AOD 304 is driven by a drive signal applied from the second RF driver 318, a portion of the laser energy incident on the AO unit of the second AOD 304 (i.e., propagating along the first-order beam path 112') is diffracted to propagate along its first-order beam path 112" (and eventually propagates to the scanning lens 108), and another portion of the incident laser energy propagates along the zero-order beam path 308. If no drive signal is applied from the second RF driver 318, the laser energy incident on the AO unit of the second AOD 304 propagates only along the zero-order beam path 308.

[0030] Typically, when the AOD is driven in response to an applied drive signal, the ratio of the optical power diffracted into the first-order beam path 112 to the optical power diffracted into the zero-order beam path is determined by the amplitude of the RF power in the applied drive signal and, in some cases, by the frequency of the RF power in the applied drive signal. Furthermore, the amount of optical power diffracted into the first-order beam path 112 increases with increasing RF power until it reaches a maximum value at a certain saturation point of the RF power. The action of setting or otherwise modulating the amplitude of the RF power in the drive signal to be applied to the AOD is referred to herein as "amplitude modulation control." The action of setting or otherwise adjusting the amount of optical power diffracted into the first-order beam path 112 can be considered as setting or adjusting the "transmission" of the AOD.

[0031] In a specific example where the AOD comprises multiple transducers, the transmission of the AOD can also be adjusted by applying drive signals to each of the transducers, wherein the applied drive signals have the same RF frequency but are slightly out of phase with each other. Therefore, the acoustic waves generated within the AO unit of the AOD interfere with each other in at least a slightly destructive manner. This destructive interference has the effect of reducing the transmission of the AOD, and thus the degree to which the AOD transmission is reduced corresponds to the degree to which the acoustic waves destructively interfere with each other within the AO unit. The act of selecting or otherwise modulating the phase relationship of the drive signals to be applied to the different transducers of the common AOD is referred to herein as "phase modulation control." However, it should be noted that phase modulation control cannot be used to completely prevent optical power from diffracting into the first-order beam path 112.

[0032] By using drive signals of different frequencies to successively drive the first AOD 302 and the second AOD 304 (e.g., during a workpiece processing cycle), the AOD scanning system 300 can be operated to rapidly deflect the first-order beam path 112" to different positions within a two-dimensional scanning field that can be projected onto the workpiece 102 by the scanning lens 108. During the workpiece processing cycle, amplitude modulation control and / or phase modulation control (e.g., varying according to the frequency of the drive signals) can be used to drive one or both of the first AOD 302 and the second AOD 304 to ensure that the amount of optical power propagating along the first-order beam path 112" is at least substantially constant, regardless of the frequency of the drive signals applied to the first AOD 302 and the second AOD 304. Alternatively, during the workpiece processing cycle, amplitude modulation control and / or phase modulation control (e.g., varying according to the frequency of the drive signal) can be used to drive one or both of the first AOD 302 and the second AOD 304 to modulate the optical power propagating along the first-order beam path 112" in any desired or suitable manner, regardless of the frequency of the drive signal applied to the first AOD 302 and the second AOD 304.

[0033] As described above, the first beam trap 310 of the AOD scanning system 300 prevents the zero-order beam path 306 from reaching the AO cell of the second AOD 304, thereby avoiding the problem discussed above with respect to Figure 2 (regarding the unsuitable constant or static thermal gradient within the AO cell of the second AOD 304). However, since Figure 3It will be apparent that the AO unit of the first AOD 302 will always be exposed to laser energy propagating along the beam path 112, while the AO unit of the second AOD 304 will only be exposed to laser energy propagating from the first AOD 302 along the first-order beam path 112'. That is, when the first AOD 302 is driven by the first RF driver 316 to generate a first-order beam propagating along the first-order beam path 112', the AO unit of the second AOD 304 will only be exposed to the laser energy beam. Therefore, the wavefront distortion effect caused by the thermal gradient within the AO unit of the second AOD 304 can become undesirably unstable and lead to problems such as those discussed above.

[0034] To advantageously stabilize the wavefront distortion effect caused by the thermal gradient within the AO unit of the second AOD 304 according to a specific embodiment of the invention, the first AOD 302 is driven (in response to one or more drive signals applied by the first RF driver 316 as commanded by the controller 320) to propagate the laser energy beam along the first-order beam path 112' to the AO unit of the second AOD 304 continuously (or almost continuously, as will be discussed in more detail below), regardless of whether the laser energy beam is being used to process the workpiece 102. Thus, the laser energy beam propagating along the first-order beam path 112' is continuously (or almost continuously) deflected into the AO unit of the second AOD 304 to increase the stability of the thermal gradient therein.

[0035] The second AOD 304, illuminated by the laser energy beam propagating from the first-order beam path 112', can thus be driven (in response to one or more drive signals applied by the second RF driver 318 in response to a command from the controller 320) to propagate the laser energy beam along the first-order beam path 112'. For example, if workpiece 102 is to be processed (e.g., during a workpiece processing cycle), the second AOD 304 can be driven in any known or otherwise suitable manner to deflect the first-order beam path 112' to the galvanometer mirror scanning system (which in turn deflects the incident laser energy beam to the scanning lens 108). In another instance, the second AOD 304 may be driven in any known or otherwise suitable manner to deflect the first-order beam path 112" to the moving beam trap 314 (e.g., if there is a long distance between features to be formed sequentially in workpiece 102 during workpiece processing, while workpiece 102 is being removed from (or loaded into) the system, etc.). As used herein, the period during which the first-order beam path 112" deflects to the moving beam trap 314 is referred to herein as the "beam trap motion period".

[0036] Figure 4 A timing diagram is shown for driving the first AOD 302 and the second AOD 304 during workpiece handling and beam trap motion cycles. Figure 4 In this diagram, the transmission of the first AOD 302, driven in response to a series of drive signals successively applied to the first AOD 302 by the first RF driver 316, is indicated by line 400. Similarly, the frequency of each RF drive signal successively applied to the transducer of the second AOD 304 by the second RF driver 318 is indicated by line 402. Furthermore, the workpiece processing cycle is represented by cycle 404 (e.g., a first workpiece processing cycle 404 that begins at a time point before time t1 and ends at time t1, and a second workpiece processing cycle 404 that begins at time t4 and ends at a time point after time t4, as illustrated). The beam trap motion cycle is represented by cycle 406, which begins at time t2 and ends at time t3.

[0037] During workpiece processing cycle 404, the frequency of any drive signal applied to the second AOD 304 is within a first frequency range (also referred to herein as the "first processing frequency range" or "fproc"), and during beam trap motion cycle 406, the frequency of any drive signal applied to the second AOD 304 is within a second frequency range (also referred to herein as the "motion frequency range" or "fex"). The first processing frequency range f... proc The frequency range traversed (i.e., the difference between the maximum and minimum frequencies of the first processing frequency range) is greater than the frequency range f of the movement. ex The frequency range traversed (i.e., the difference between the maximum and minimum frequencies of the movement frequency range).

[0038] Typically, the first processing frequency range f proc With motion frequency range f ex They are not continuous or adjacent. That is, the first processing frequency range f proc The maximum frequency (i.e., f) proc_max ) and the range of motion frequency f ex The minimum frequency (i.e., f) ex_min There is a step size difference between them. The maximum frequency f in the first processing frequency range. proc_max The minimum frequency f in the range of motion frequencies ex_minThe magnitude of the step difference between the two (i.e., the threshold value). If the magnitude of the frequency difference between any two drive signals (e.g., the first drive signal and the second drive signal) to be successively applied to the second AOD 304 is greater than or equal to the threshold value, one or more transient acoustic waveforms will be generated in the AO unit of the second AOD 304. Such a transition between the frequencies of the first and second drive signals, which causes the generation of transient acoustic waveforms, is referred to herein as a "transient event". If the laser energy beam propagating through the AOD unit of the second AOD 304 is diffracted by such transient acoustic waveforms, the spatial power distribution of the light spot illuminating the workpiece 102 will become undesirably distorted, thereby preventing the workpiece 102 from being satisfactorily processed. Transient acoustic waveforms can also be generated in the AO unit of the first AOD 302 by driving the first AOD 302 in the same manner as described with respect to the second AOD 304.

[0039] To prevent transient acoustic waveforms within the AO unit of the second AOD 304 from adversely affecting the ability to satisfactorily process workpiece 102, the transmission of the first AOD 302 is reduced by implementing amplitude modulation control, phase modulation control, or any combination thereof during the operation of the first AOD 302, or by ceasing the application of drive signals to the first AOD 302 only during a period prior to a transient event (also referred to herein as the "transient decay period"). For example, the controller 320 may analyze data representing the distance along a second axis or otherwise associated with each pair of spot positions at workpiece 102 to be successively irradiated after the operation of the AOD scanning system 300 (or only the second AOD 304), and if the analysis indicates that a transient event will occur, the controller 320 may output a control signal to reduce the transmission of the first AOD 302.

[0040] As the name suggests, the duration of the transient decay period is long enough that by the time the transient event is about to occur, any acoustic waves within the AO unit of the first AOD 302 will have attenuated (e.g., attenuated to zero amplitude or close to zero amplitude). Therefore, by the time the transient event is about to occur, the first AOD 302 will not output any first-order laser energy beam along the first-order beam path 112' to the AO unit of the second AOD 304 (or if it outputs a first-order laser energy beam, the power in the output laser energy beam will be insufficient to affect the processing of the workpiece 102). According to a specific embodiment of the invention, the duration of the transient decay period 408 may be equal to or about 2 μs, 1 μs, 0.5 μs, 0.25 μs, 0.1 μs, etc., or between these values, depending on one or more factors, such as the amplitude and velocity of the acoustic wave propagating in the AO unit of the first AOD 302, the size of the optical aperture of the first AOD 302, the diameter of the incident laser energy beam incident on the AO unit of the first AOD 302, or similar factors, or any combination thereof. Figure 4 In the example, the transient decay period is shown as 408, and the transient event is shown illustratively as occurring at times t2 and t4.

[0041] exist Figure 4 In the exemplary specific examples shown, the first processing frequency range f proc The maximum frequency (i.e., f) proc_max ) and the first processing frequency range f proc The minimum frequency (i.e., f) proc_min The difference between the values ​​is less than the aforementioned threshold value. However, in another specific instance, the first processing frequency range f proc The maximum frequency (i.e., f) proc_max ) and the first processing frequency range f proc The minimum frequency (i.e., f) proc_min The magnitude of the difference between the two values ​​can be greater than or equal to the threshold value. In such specific instances, the frequency difference between the drive signals to be successively applied to the second AOD 304 will typically be less than the threshold value. However, there may be times when the frequency difference between the drive signals to be successively applied to the second AOD 304 will typically be greater than or equal to the threshold value (e.g., when the distance between the features to be successively formed in the workpiece 102, measured along the aforementioned second axis during the workpiece processing cycle 404, is relatively long). In such cases, the first AOD 302 is operated (e.g., as discussed above) to allow the transient acoustic wave to ideally attenuate during the transient attenuation period prior to the transient event.

[0042] although Figure 4The transmission of the first AOD 302 is illustrated as constant (or substantially constant) during each workpiece processing cycle 404 and beam trap motion cycle 406, but it should be understood that the transmission of the first AOD 302 may be adjusted during any workpiece processing cycle 404 or beam trap motion cycle 406 (e.g., by implementing amplitude modulation control, phase modulation control or any combination thereof).

[0043] Although not illustrated, it should be understood that the frequencies of the RF drive signals successively applied from the first RF driver 316 to the transducer of the first AOD 302 during workpiece processing cycle 404 may be within a frequency range (also referred to herein as the "second processing frequency range"). The second processing frequency range may be the same as or different from the first processing frequency range. For example, the frequencies spanned by the second processing frequency range may be the same as or different from the frequencies spanned by the first processing frequency range, the magnitude of the second processing frequency range may be the same as or different from the magnitude of the first processing frequency range, or similar to, or any combination thereof.

[0044] Typically, the difference between the maximum frequency and the minimum frequency of the second processing frequency range can be less than, equal to, or greater than the aforementioned threshold value. If the frequency difference between the drive signals to be successively applied to the first AOD 302 is greater than or equal to the threshold value (e.g., when the distance between the features to be successively formed in the workpiece 102, measured along the aforementioned first axis during the workpiece processing cycle 404, is relatively long), the second AOD 304 can be operated (e.g., as discussed above with respect to the first AOD 302) to allow the transient acoustic wave to ideally attenuate during the transient attenuation period prior to the transient event in the first AOD 302.

[0045] Although not shown, the drive signal applied from the second RF driver 318 to the transducer of the second AOD 304 can cause the second AOD 304 to operate with a constant (or substantially constant) or variable transmission during any workpiece processing cycle 404 or beam trap motion cycle 406 (e.g., by implementing amplitude modulation control, phase modulation control or any combination thereof).

[0046] VII. Additional Notes

[0047] Typically, controller 320 includes one or more processors operable to (e.g., immediately after executing one or more instructions) generate the aforementioned commands and control signals. The processor may be provided as a programmable processor operable to execute instructions (e.g., including one or more general-purpose computer processors, microprocessors, digital signal processors, or any other suitable form of circuit system, including programmable logic devices (PLDs), central processing units (CPUs), graphics processing units (GPUs), accelerated processing units (APUs), real-time processing units (RPUs), field-programmable gate arrays (FPGAs), field-programmable object arrays (FPOAs), application-specific integrated circuits (ASICs)—including digital, analog, and mixed-signal analog / digital circuit systems—or similarities, or any combination thereof). Instruction execution may occur on a single processor, distributed among multiple processors, across processors within a device, or across a network of devices in parallel, or similar combinations thereof.

[0048] Typically, instructions can be implemented as software (e.g., executable code, files, library files, or the like, or any combination thereof), hardware configuration (e.g., in the case of FPGA, ASIC, etc.), or the like thereof, or any combination thereof, which can be readily specified by those skilled in the art based on the description provided herein (e.g., written in C, C++, Visual Basic, Java, Python, Tel, Perl, Scheme, Ruby, assembly languages, hardware description languages ​​such as LUCID, VHDL, or VERILOG, etc.). Software is typically stored in one or more data structures conveyed by tangible media such as computer memory, which can be accessed 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 discs, volatile or non-volatile semiconductor memories (e.g., RAM, ROM, NAND flash memory, NOR flash memory, SONOS memory, etc.), or the like thereof, or any combination thereof, and can be accessed locally, remotely (e.g., across a network), or any combination thereof.

[0049] VIII. Conclusion

[0050] The foregoing describes specific examples and embodiments of the present invention and should not be construed as limiting the specific examples and embodiments of the present invention. Although several specific examples and embodiments have been described with reference to the drawings, those skilled in the art will readily understand that many modifications and other specific embodiments are possible to the disclosed specific examples and embodiments without substantially departing from the novel teachings and advantages of the present invention. For example, although specific examples relating to motion operations have been described above as being related to... Figure 3 The beam traps shown in Figure 2 are used together, but it should be understood that the first AOD 200 in the beam trap 106 shown in Figure 2 can also be driven to perform the motion operations described herein. In another example, although beam trap motion has been described above as involving the use of a moving beam trap 314 of the AOD scanning system 300, it should be understood that in another specific example, the moving beam trap 314 can be replaced by one or more optical components (e.g., one or more mirrors, lenses, or the like, or any combination thereof) configured to intercept laser energy propagating along the first beam path 112" during beam trap motion operation and to redirect the laser energy to the first beam trap 310 or the second beam trap 312. In yet another specific example, the second beam trap 312 can be configured to intercept laser energy propagating from the second AOD 304 along the first beam path 112" during beam trap motion operation.

[0051] Therefore, all such modifications are intended to be included within the scope of the invention as defined in the claims. For example, those skilled in the art will understand that the subject matter of any sentence, paragraph, instance, or specific example may be combined with some or all of the subject matter of other sentences, paragraphs, instances, or specific examples, unless such combinations are mutually exclusive. Therefore, the scope of the invention should be determined by the following claims, wherein the equivalents of the claims are included in the claims.

Claims

1. A system comprising: An acousto-optic deflector scanning system operable to deflect a beam path from which a laser energy beam can propagate, the acousto-optic deflector scanning system comprising: A first acousto-optic deflector is configured and operable to deflect the beam path along a first axis in response to a first drive signal; A second acousto-optic deflector is configured and operable in response to a second drive signal to deflect the beam path deflected by the first acousto-optic deflector along a second axis. A first driver is connected to the first acousto-optic deflector and is operable to generate the first drive signal. A second driver is connected to the second acousto-optic deflector and is operable to generate the second drive signal; and A controller, connected to and operable to control the operation of the first driver and the second driver. The controller is operable to control the operation of one of the first driver or the second driver to deflect the beam path from a first position to a second position, and The controller is operable to control the operation of the first driver or the other of the second drivers to reduce the transmission of laser energy in the deflected beam path during a period of time, wherein the period of time ends when the operation of the first driver or the second driver is controlled to deflect the beam path from the first position to the second position.

2. The system of claim 1, wherein one of the first driver or the second driver is the first driver, and the other of the first driver or the second driver is the second driver.

3. The system of claim 1, wherein one of the first driver or the second driver is the second driver, and the other of the first driver or the second driver is the first driver.

4. The system of claim 1, wherein the controller is operable to control the operation of the other of the first driver or the second driver by means of an amplitude modulation that generates a drive signal, so that the acousto-optic deflector connected thereto reduces the transmission of laser energy.

5. The system of claim 1, wherein the controller is operable to control the operation of the other of the first driver or the second driver by phase modulation of the generated drive signal, so that the acousto-optic deflector connected thereto reduces the transmission of laser energy.

6. The system of claim 1, wherein the time period corresponds to the decay period of the transient acoustic wave within the acousto-optic deflector connected to the first driver or the second driver.

7. The system of claim 1, wherein the time period is between 2 μs and 0.1 μs.

8. The system of claim 1, further comprising a first beam trap configured to intercept laser energy propagating along the zero-order beam path of the first acousto-optic deflector.

9. The system of claim 8, further comprising at least one optical component configured and configurable to redirect the laser energy propagation beam path deflected by the second acousto-optic deflector to the first beam trap.

10. The system of claim 1, further comprising a second beam trap configured to intercept laser energy propagating along the zero-order beam path of the second acousto-optic deflector.

11. The system of claim 10, wherein the second beam trap is configured to intercept laser energy propagating along the beam path deflected by the second acousto-optic deflector.

12. The system of claim 10, further comprising a third beam trap configured to intercept the laser energy propagation beam path deflected by the second acousto-optic deflector.

13. The system of claim 10, further comprising at least one optical component configured and configurable to redirect the laser energy propagation beam path deflected by the second acousto-optic deflector to the second beam trap.

14. The system of claim 10, further comprising an optically disposed downstream of the acousto-optic deflector scanning system, the scanning lens being configured to focus laser energy propagating along the beam path deflected by the acousto-optic deflector scanning system.

15. The system of claim 14, further comprising a scanning system optically disposed between the acousto-optic deflector scanning system and the scanning lens, the scanning system being operable to deflect the beam path deflected by the acousto-optic deflector scanning system.

16. A controller for use with an acousto-optic deflector scanning system operable to deflect a beam path from which a laser energy beam can propagate, the acousto-optic deflector scanning system comprising: a first acousto-optic deflector configured and operable in response to a first drive signal to deflect the beam path along a first axis; and a second acousto-optic deflector configured and operable in response to a second drive signal to deflect the beam path deflected by the first acousto-optic deflector along a second axis. A first driver connected to the first acousto-optic deflector and operable to generate the first drive signal; and a second driver connected to the second acousto-optic deflector and operable to generate the second drive signal, the controller comprising: At least one processor; and A memory accessible by the at least one processor, wherein the memory stores instructions that, when executed by the at least one processor, cause the controller to control the operation of the acousto-optic deflector scanning system to: Controlling the operation of one of the first driver or the second driver to deflect the beam path from the first position to the second position, and The operation of the first driver or the other of the second drivers is controlled to reduce the transmission of laser energy in the deflected beam path during a period of time, wherein the period of time ends when the operation of the first driver or the second driver is controlled to deflect the beam path from the first position to the second position.

17. A non-transitory computer-readable medium for use with a controller, the controller being capable of controlling an acousto-optic deflector scanning system operable to deflect a beam path from which a laser energy beam can propagate, the acousto-optic deflector scanning system comprising: a first acousto-optic deflector configured and operable to deflect the beam path along a first axis in response to a first drive signal; a second acousto-optic deflector configured and operable to deflect the beam path deflected by the first acousto-optic deflector along a second axis in response to a second drive signal; a first driver connected to the first acousto-optic deflector and operable to generate the first drive signal; and a second driver connected to the second acousto-optic deflector and operable to generate the second drive signal, the non-transitory computer-readable medium specifically implementing instructions that, when executed by the controller, cause the controller to: Controlling the operation of one of the first driver or the second driver to deflect the beam path from the first position to the second position, and The operation of the first driver or the other of the second drivers is controlled to reduce the transmission of laser energy in the deflected beam path during a time period, wherein the time period ends when the operation of the first driver or the second driver is controlled to deflect the beam path from the first position to the second position.

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