Passive dispersion compensation for acousto-optic deflectors

Abstract

An optical scanner may include one or more acousto-optic deflectors (AODs) configured to deflect a light beam along one or more scanning directions, where a deflection angle of the light beam from the one or more AODs may be controlled by one or more drive signals applied to the one or more AODs. The scanner may further include a dispersion compensator wherein a dispersion of the dispersion compensator at least partially compensates for a dispersion of the one or more AODs to provide that the deflection angle of the light beam is constant for a wavelength of the light beam within a range of wavelengths within a first tolerance in a particular configuration of the one or more drive signals, and wherein at least one of the dispersion of the dispersion compensator or the transmittance of the dispersion compensator is independent of polarization of the light beam within a second tolerance.

Description

Technical Field

[0001] The present disclosure relates generally to a beam scanner, and more particularly to passive dispersion correction for a beam scanner in the presence of spectral variations of the scanning beam. Background Art

[0002] Acoustic optical deflectors (AODs) can be used as beam scanning devices in a wide range of applications. AODs advantageously provide relatively fast scanning speeds, but are sensitive to spectral variations of the scanned beam. Therefore, it would be desirable to develop systems and methods that address the above deficiencies. Summary of the invention

[0003] According to one or more illustrative embodiments of the present disclosure, an optical scanner is disclosed. In one illustrative embodiment, the scanner includes one or more acousto-optic deflectors (AODs), the one or more AODs being configured to deflect a light beam along one or more scanning directions, wherein the deflection angle of the light beam from the one or more AODs can be controlled by one or more drive signals applied to the one or more AODs. In another illustrative embodiment, the scanner includes a dispersion compensator, wherein the dispersion of the dispersion compensator at least partially compensates for the dispersion of the one or more AODs to provide that under a specific configuration of the one or more drive signals, the one or more AODs and the dispersion compensator are constant within a first tolerance for the wavelength of the light beam within a wavelength range, and wherein at least one of the dispersion of the dispersion compensator or the transmittance of the dispersion compensator is independent of the polarization of the light beam within a second tolerance.

[0004] A method is disclosed according to one or more illustrative embodiments of the present disclosure. In one illustrative embodiment, the method includes deflecting a light beam along one or more scanning directions with an AOD, wherein the deflection angle of the light beam from the AOD can be controlled by one or more drive signals applied to the AOD. In another illustrative embodiment, the method includes dispersing the light beam with a dispersion compensator, wherein the dispersion of the dispersion compensator at least partially compensates for the dispersion of the AOD, so that under a specific configuration of the one or more drive signals, the deflection angle of the light beam from the AOD and the dispersion compensator is constant within a first tolerance for the wavelength of the light beam within a wavelength range, and wherein at least one of the dispersion of the dispersion compensator or the transmittance of the dispersion compensator is independent of the polarization of the light beam within a second tolerance.

[0005] According to one or more illustrative embodiments of the present disclosure, an optical scanner is disclosed. In one illustrative embodiment, the scanner includes a dispersion compensator formed as a diffractive optical element (DOE), the diffractive optical element being configured to diffract a light beam into two or more diffracted light beams along two or more directions, wherein at least one of the dispersion of the dispersion compensator or the transmittance of the dispersion compensator is independent of the polarization of the light beam within a first tolerance. In another illustrative embodiment, the scanner includes two or more AODs to receive the two or more diffracted light beams and deflect the two or more diffracted light beams, wherein the deflection angle of the diffracted light beams from the two or more AODs can be controlled by a drive signal applied to the two or more AODs, and wherein the dispersion of the dispersion compensator at least partially compensates for the dispersion of the two or more AODs to provide that under a specific configuration of the one or more drive signals, the dispersion compensator and the two or more AODs are constant within a second tolerance for the wavelength of the light beam within a wavelength range.

[0006] A system is disclosed according to one or more illustrative embodiments of the present disclosure. In one illustrative embodiment, the system includes a light source configured to generate a light beam. In another illustrative embodiment, the system includes a scanner. In another illustrative embodiment, the scanner includes one or more AODs, the one or more AODs are configured to deflect the light beam along one or more scanning directions, wherein the deflection angle of the light beam from the one or more AODs can be controlled by one or more drive signals applied to the one or more AODs. In another illustrative embodiment, the scanner includes a dispersion compensator, wherein the dispersion of the dispersion compensator at least partially compensates for the dispersion of the one or more AODs, so that under a specific configuration of the one or more drive signals, the dispersion compensator and the one or more AODs are constant within a first tolerance for the wavelength of the light beam within a wavelength range, and wherein at least one of the dispersion of the dispersion compensator or the transmittance of the dispersion compensator is independent of the polarization of the light beam within a second tolerance. In another illustrative embodiment, the system includes one or more focusing optics configured to focus the light beam deflected by the one or more AODs to a sample.

[0007] It should be understood that both the foregoing summary and the following detailed description are exemplary and explanatory only and do not necessarily limit the invention as claimed.The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the summary serve to explain the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Those skilled in the art may better appreciate the numerous advantages of the present disclosure by referring to the accompanying drawings.

[0009] Figure 1 is a block diagram of an optical scanner according to one or more embodiments of the present disclosure.

[0010] Figure 2 is a simplified schematic diagram of an acousto-optic deflector (AOD) according to one or more embodiments of the present disclosure.

[0011] Figure 3A is a simplified schematic diagram of an AOD exhibiting dispersion according to one or more embodiments of the present disclosure.

[0012] Figure 3B According to one or more embodiments of the present disclosure Figure 3A Simplified schematic diagram of a dispersion compensator with opposite dispersion to the AOD.

[0013] Figure 4 is a block diagram of an optical scanner including a dispersion compensator 108 positioned before the AOD in the path of the optical beam, according to one or more embodiments of the present disclosure.

[0014] Figure 5 is a simplified schematic diagram of an optical scanner including a dispersion compensator before the AOD in the path of the optical beam in accordance with one or more embodiments of the present disclosure.

[0015] Fig. 6A is a block diagram of an optical scanner including an optical relay to image a dispersion compensator onto an AOD according to one or more embodiments of the present disclosure.

[0016] Figure 6B is a simplified schematic diagram of an optical scanner including an optical relay to image a dispersion compensator onto an AOD according to one or more embodiments of the present disclosure.

[0017] Figure 7 is a conceptual diagram of a dispersion compensator and relative dispersion directions of a single AOD arranged for 1D scanning in the YZ plane according to one or more embodiments of the present disclosure.

[0018] Figure 8 is a conceptual diagram of a dispersion compensator and relative dispersion directions of two AODs arranged for 2D scanning according to one or more embodiments of the present disclosure.

[0019] Fig. 9 is a block diagram of an optical scanner having a polarization-insensitive dispersion compensator arranged to provide dispersion compensation for two orthogonal polarization-sensitive AODs according to one or more embodiments of the present disclosure.

[0020] Fig.10 is a block diagram of an optical scanner including a beam splitter to split a received light beam into four channels, each channel including at least one AOD, according to one or more embodiments of the present disclosure.

[0021] Fig.11 is a block diagram of an optical scanner including a dispersion compensator that provides both dispersion compensation and beam splitting in accordance with one or more embodiments of the present disclosure.

[0022] Fig.12 is a block diagram of a system including an optical scanner according to one or more embodiments of the present disclosure.

[0023] Fig.13 is a flow chart illustrating steps performed in a method for passive dispersion compensation for an acousto-optic deflector according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION

[0024] Reference will now be made in detail to the disclosed subject matter illustrated in the accompanying drawings. The present disclosure has been particularly shown and described with respect to specific embodiments and specific features thereof. The embodiments set forth herein should be regarded as illustrative rather than restrictive. It should be readily apparent to one of ordinary skill in the art that various changes and modifications in form and detail may be made without departing from the spirit and scope of the present disclosure.

[0025] Embodiments of the present disclosure relate to systems and methods for passive dispersion correction of an acousto-optic deflector (AOD) to compensate for spectral variations of a light beam (e.g., a laser beam or the like). In some embodiments, an optical scanner includes an acousto-optic deflector (AOD) and a dispersion compensator to receive and redirect a light beam (e.g., a scanning light beam).

[0026] The AOD may include one or more transducers to generate acoustic waves in a host material, wherein driving the transducers with a periodic drive signal may form a diffraction grating in the host material. In this way, an incident light beam may be redirected via diffraction, wherein the deflection angle of the light beam from the AOD (e.g., the diffraction angle from the diffraction grating) may be controlled based on the frequency of the drive signal, and the intensity of the light beam from the AOD may be controlled based on the amplitude of the drive signal.

[0027] It is contemplated herein that such an AOD may advantageously provide scanning speeds higher than mechanical scanners (e.g., galvanometers, rotating polygons, or the like), but may be highly sensitive to spectral variations of the scanned light beam. In particular, spectral variations of the light beam may result in changes in the diffraction angle of the light beam by the AOD and thus changes in the deflection angle of the light beam. However, the systems and methods disclosed herein may allow for passive compensation of spectral variations to provide fast and accurate optical scanning with the AOD, regardless of spectral variations.

[0028] In some embodiments, the optical scanner includes a dispersion compensator having an opposite dispersion to the AOD (e.g., dispersion of equal magnitude and opposite direction). Thus, light of different wavelengths from the dispersion compensator can be incident on the AOD at different angles to provide the same deflection angle for different wavelengths. Thus, the optical scanner can provide a precise deflection angle (e.g., pointing direction) regardless of the spectral variation of the scanned light beam.

[0029] In some embodiments, the dispersion compensator is polarization insensitive. In this way, the incident light beam can have any suitable polarization, and in some cases can be unpolarized. It is contemplated herein that polarization insensitivity can facilitate higher power of the light beam, particularly when the light beam from the light source is unpolarized.

[0030] In some embodiments, the dispersion compensator and AOD are compatible with operation in mid-infrared (MIR) wavelengths. For example, the dispersion compensator and AOD can be formed of a material suitable for operation with a beam from a CO2 laser (e.g., ZnSe or the like), which can operate at wavelengths in the 9 to 12 micron range.

[0031] Reference Figures 1 to 12 , according to one or more embodiments of the present disclosure, a system and method for passive dispersion correction of an acousto-optic deflector (AOD) are described in more detail.

[0032] Figure 1 is a block diagram of an optical scanner 100 according to one or more embodiments of the present disclosure.

[0033] In some embodiments, the optical scanner 100 is configured to receive a light beam 102 (eg, from a light source 104 ), the AOD 106 is used to control the deflection angle of the light beam 102 , and the dispersion compensator 108 has a dispersion opposite to that of the AOD 106 to at least partially compensate for the dispersion in the AOD 106 .

[0034] The light beam 102 may include light of one or more selected wavelengths, including but not limited to ultraviolet (UV) radiation, visible radiation, or infrared (IR) radiation. In addition, the light beam 102 from the light source 104 may have any temporal profile, including but not limited to a continuous wave (CW) profile, a pulse profile, or a modulated profile.

[0035] The light source 104 may generally include any type of illumination source suitable for providing at least one light beam 102, including but not limited to a laser source or a light emitting diode (LED). It should be noted that the light source 104 may be integrated into the optical scanner 100, the system 1200, or as an external component. In some embodiments, the light source 104 includes a narrowband laser source that provides light centered around a central wavelength. It is contemplated herein that the smaller the bandwidth of the light beam 102, the less spatial dispersion will be induced by a dispersive element (such as but not limited to the AOD 106).

[0036] In some embodiments, the light source 104 is a carbon dioxide (CO2) laser source. For example, a CO2 laser can provide a light beam 102 having a wavelength in the range of 9 to 12 microns, but this is intended to be illustrative and not limiting.

[0037] The optical scanner 100 may further include a controller 110 having one or more processors 112 configured to execute a set of program instructions maintained in a memory 114 (e.g., a memory device), wherein the controller 110 may generate at least one drive signal 116 for the AOD 106. In this manner, the controller 110 may direct or otherwise control the AOD 106 based on the drive signal 116 (e.g., based on the frequency of the drive signal 116) to direct the light beam 102 along a particular deflection angle, scanning pattern, or the like.

[0038] The one or more processors 112 of the controller 110 may include any processor or processing element known in the art. In this sense, the one or more processors 112 may include any microprocessor-type device configured to execute algorithms and / or instructions. For the purposes of this disclosure, the term "processor" or "processing element" may be broadly defined to encompass any device having one or more processing or logic elements (e.g., one or more microprocessor devices, one or more application specific integrated circuit (ASIC) devices, one or more field programmable gate arrays (FPGAs), or one or more digital signal processors (DSPs)). In this sense, the one or more processors 112 may include any device configured to execute algorithms and / or instructions (e.g., program instructions stored in a memory). In some embodiments, the one or more processors 112 may be embodied as a desktop computer, a mainframe computer system, a workstation, an image computer, a parallel processor, a networked computer, or any other computer system configured to execute a program configured to operate the optical scanner 100 or operate in conjunction with the optical scanner 100, as described throughout this disclosure. In addition, the different subsystems of the optical scanner 100 may include processors or logic elements suitable for implementing at least a portion of the steps described in the present disclosure. Therefore, the above description should not be interpreted as a limitation on the embodiments of the present disclosure but is merely illustrative. In addition, the steps described throughout the present disclosure may be implemented by a single controller or alternatively multiple controllers. In addition, the controller 110 may include one or more controllers housed in a common housing or multiple housings. In this way, any controller or combination of controllers can be separately packaged as a module suitable for integration into the optical scanner 100.

[0039] The memory 114 may include any storage media known in the art suitable for storing program instructions that can be executed by the associated one or more processors 112. For example, the memory 114 may include a non-transitory storage medium. By way of another example, the memory 114 may include, but is not limited to, a read-only memory (ROM), a random access memory (RAM), a magnetic or optical storage device (e.g., a disk), a tape, a solid-state drive, and the like. It should be further noted that the memory 114 may be housed in a common controller housing with the one or more processors 112. In some embodiments, the memory 114 may be remotely located relative to the physical location of the one or more processors 112 and the controller 110. For example, the one or more processors 112 of the controller 110 may access a remote memory (e.g., a server) that is accessible via a network (e.g., the Internet, an intranet, and the like).

[0040] Reference Figures 2 to 11 , according to one or more embodiments of the present disclosure, the operation of the AOD 106 and the dispersion compensator 108 for at least partially compensating for the dispersion of the AOD 106 are described in more detail.

[0041] AOD 106 may include any type of deflector known in the art suitable for controlling the deflection angle of light beam 102 by diffraction of acoustic waves in a material. Figure 2 is a simplified schematic diagram of the AOD 106 according to one or more embodiments of the present disclosure.

[0042] In some embodiments, AOD 106 includes at least one transducer 202 coupled to a body material 204. Body material 204 may include any type of material suitable for interacting with light beam 102, such as, but not limited to, glass or crystal. For example, body material 204 may be transparent to light beam 102. As an illustration, body material 204 may have an absorptivity of a wavelength associated with light beam 102 below a selected threshold and / or may have a transmittance of a wavelength associated with light beam 102 above a selected threshold.

[0043] Transducer 202 may be any component suitable for generating acoustic waves in body material 204. In some embodiments, transducer 202 is a piezoelectric material that can expand or contract in response to an applied voltage (eg, drive signal 116), which can generate acoustic waves in body material 204.

[0044] In some embodiments, the AOD 106 (e.g., one or more transducers in the AOD 106) is driven by the periodic drive signal 116 to generate a periodic distribution of acoustic waves in the bulk material 204, which may operate as a diffraction grating 206 suitable for diffracting the light beam 102. In particular, the periodic distribution of acoustic waves may provide a periodic distribution of refractive index in the bulk material 204 operating as the diffraction grating 206.

[0045] Diffraction of the light beam 102 by the diffraction grating 206 may generally result in any number of diffraction orders (e.g., zeroth order diffraction 208, first order diffraction 210, second order diffraction 212, or the like). Diffraction of the light beam 102 by the diffraction grating 206 in the AOD 106 may generally be governed by the grating equation:

[0046] d(sinθ i -sinθ m )=mλ (1)

[0047] Where d is the period of the diffraction grating 206, m is the diffraction order, λ is the wavelength of the light beam 102, θ i is the incident angle of the light beam 102, and θ m is the diffraction angle of the associated diffraction order of the light beam 102 .

[0048] In this configuration, any diffraction order can be used as the deflected beam 102. In this way, the deflection angle 214 of the beam 102 can correspond to the diffraction angle (θ m ).

[0049] In some embodiments, the AOD 106 is configured such that the light beam 102 interacts with the diffraction grating 206 at or near the Bragg angle such that a majority of the energy in the light beam 102 is diffracted into a first order diffraction 210 (e.g., a +1st order diffraction or a -1st order diffraction). Thus, the first order diffraction 210 may represent a deflected light beam 102, and a deflection angle 214 of the light beam 102 from the AOD 106 may correspond to a first order diffraction angle 216.

[0050] In this configuration, the deflection angle 214 corresponds to the first order diffraction angle 216:

[0051] 01=asin(sinθi-λ\d)(2)

[0052] More generally, equations (1) and (2) illustrate that the non-zero diffraction orders, including but not limited to the first order diffraction 210, are spectrally dispersed such that the diffraction angle θ varies based on the wavelength (λ) of the light beam 102. In other words, the AOD 106 may exhibit angular dispersion (D) that causes the deflection angle 214 of the light beam to vary as a function of wavelength (λ), which may be generally characterized as:

[0053]

[0054] Wherein m can be, but is not required to be, 1 to correspond to the first order diffraction 210 .

[0055] The power of the first order diffraction 210, and therefore the efficiency of the AOD 106 for deflecting the light beam 102, may depend on various factors, including, but not limited to, the magnitude of the change in the refractive index of the host material 204 associated with the diffraction grating 206 (Δn, where n is the refractive index of the host material 204), which may be referred to as the modulation depth of the diffraction grating 206. In the AOD 106, this modulation depth (Δn) may be based on the amplitude of the acoustic wave generated by the transducer 202.

[0056] For a given wavelength (λ) of the light beam 102, the first order diffraction angle 216, and thus the deflection angle 214 of the light beam 102 from the AOD 106, may be varied within a scanning range (e.g., a walking window) by adjusting the frequency of the drive signal 116. The period (d) of the diffraction grating 206 may be inversely related to the frequency of the drive signal 116. For example, the controller 110 may generate the drive signal 116 and may adjust the frequency of the drive signal 116 in any selected pattern to adjust the deflection angle 214 in any selected pattern.

[0057] It is contemplated herein that the light source 104 may exhibit various instabilities, such as, but not limited to, instabilities in the spectrum or beam size of the light beam 102. In the case of a laser source, such instabilities may, but are not required to, be associated with mode hopping between different supported modes, each of which may have a different wavelength (e.g., a central wavelength).

[0058] Variations in the spectrum of the light beam 102 (eg, associated with such instabilities of the light source 104, or more generally associated with any mechanism) may induce errors in the deflection angle of the light beam 102. Consider Figure 2 As a non-limiting example, based on equations (1) to (3), spectral variations of the light beam 102 may affect the first-order diffraction angle 216 and, therefore, the deflection angle 214 of the light beam 102 from the AOD 106. Therefore, a deviation of the wavelength (λ) of the light beam 102 from an expected value (e.g., due to spectral variations) may result in an error in the deflection angle 214 from the AOD 106.

[0059] While such deflection angle errors may be avoided by using wavelength insensitive scanning techniques (e.g., mechanical techniques, such as, but not limited to, galvanometers or rotating polygons) or selecting a light source 104 with reduced spectral variation, such approaches are not always desirable. For example, mechanical beam scanning techniques may generally have a slow positioning rate (e.g., scanning rate), and thus may limit the throughput of the system. As another example, techniques that provide a beam 102 with high spectral stability may limit the achievable power of the beam 102. In other words, mode hopping (and associated spectral instability) may be a result of high power operation of some laser sources (e.g., but not limited to CO2 laser sources).

[0060] Therefore, it may be desirable in some applications to utilize an optical scanner 100 including an AOD 106 in combination with a light source 104 that exhibits spectral variation.

[0061] In this manner, the light source 104 may be selected to provide a light beam 102 having a selected power without sacrificing scanning speed or accuracy, and without regard to spectral instabilities.

[0062] In some embodiments, the optical scanner 100 includes a dispersion compensator 108 to at least partially compensate for the dispersion of the AOD 106 to provide a deflection angle 214 that is insensitive to spectral variations of the light beam 102 (at least within selected tolerances and within selected operating conditions).

[0063] The dispersion compensator 108 may include any optical element known in the art suitable for introducing dispersion into the light beam 102. In some embodiments, the dispersion compensator 108 is a prism (e.g., a wedge-shaped window). In some embodiments, the dispersion compensator 108 is a diffractive optical element (DOE). It is contemplated herein that providing a prism as a dispersion compensator may be impractical or impossible for certain wavelength ranges, such as, but not limited to, the mid-infrared to far-IR spectral regions. As an illustration, designing a prism suitable for dispersion compensation of wavelengths associated with a light beam from a carbon dioxide (CO2) laser system may present challenges for dispersion compensation because the number of materials that are transparent to such wavelengths is limited (e.g., ZnSe or the like) and may not provide acceptable refractive index and / or damage resistance. However, it may be the case that a DOE may be fabricated to be nearly 100% transmissive to first order diffraction at these wavelengths, and may further withstand high powers.

[0064] The dispersion compensator 108 formed as a DOE may include any type of DOE known in the art. For example, the DOE may generally include a solid material that is transparent to the wavelength of interest of the particular light beam 102, the solid material including structures arranged to impart a selected spatial distribution of optical phase on the light beam 102, which can be used to control various properties of the output light beam 102, such as, but not limited to, propagation direction, beam profile, or focal properties. For example, the DOE may have a spatially varying optical path length based on any combination of spatially varying thickness or refractive index. In addition, the dispersion compensator 108 may be a passive device and, therefore, may have a fixed dispersion property (D DC ). In some embodiments, the dispersion compensator 108 formed as a DOE includes a periodic structure (e.g., a line, a circle, a contoured shape, or the like) having a period selected to diffract the light beam 102 into one or more diffraction orders. Thus, such a DOE may be more generally characterized as a diffraction grating or a diffraction element.

[0065] Furthermore, the dispersion compensator 108 formed as a DOE may be fabricated using any suitable technique. For example, a spatially varying thickness distribution may be fabricated using, but is not required to be fabricated using, a lithographic technique based on lithographic exposure of a photoresist and subsequent etching. As another example, a spatially varying thickness distribution may be fabricated using, but is not required to be fabricated using, direct laser writing techniques or exposing a photosensitive material with a desired light pattern to induce a desired structural change in a substrate.

[0066] In some embodiments, the dispersion compensator 108 is polarization-insensitive such that the incident light beam 102 may have any suitable polarization and / or may be unpolarized. In this way, at least one of the dispersion provided by the dispersion compensator 108 or the transmittance of the dispersion compensator 108 (e.g., the power of the light beam 102 exiting the dispersion compensator 108 relative to the power of the light beam 102 entering the dispersion compensator 108) may not depend on the polarization of the incident light beam 102 (at least within a specified tolerance). For example, the dispersion and / or transmittance of the polarization-insensitive dispersion compensator 108 may be constant within a tolerance of a selected percentage of different input polarizations of the light beam 102.

[0067] It is contemplated herein that the polarization-insensitive dispersion compensator 108 may reduce the need for polarization manipulation optics, such as, but not limited to, polarizers and / or polarization retarders (e.g., polarization rotators, wave plates, or the like) to manipulate the polarization of the light beam 102 prior to the dispersion compensator 108. For certain wavelengths and / or power ranges of the light beam 102, it may be impractical to manufacture such polarization manipulation optics. As an illustration, it may be impractical to provide such polarization manipulation optics for a light beam 102 from a CO2 laser, particularly at relatively high powers, such as, but not limited to, tens to hundreds of kilowatts. For example, it may be impractical to provide birefringent materials suitable for such wavelength and power ranges. However, the polarization-insensitive dispersion compensator 108 may enable operation with a light beam 102 having any polarization characteristics.

[0068] As about Figures 8 to 9 In more detail, the polarization-insensitive dispersion compensator 108 is particularly suitable for, but not limited to, providing dispersion compensation for multiple AODs 106 (eg, oriented in orthogonal directions) with a single element. In contrast, this application would require multiple polarization-sensitive dispersion compensators, which would reduce overall throughput and increase system cost.

[0069] The polarization-insensitive dispersion compensator 108 can also facilitate higher power of the light beam when the light beam 102 from the light source 104 is unpolarized. For example, in the case where the light beam 102 from the light source 104 is unpolarized, the conversion of the light beam 102 to linear polarization (e.g., using a polarizer) can significantly reduce the available power of the light beam 102 (e.g., by as much as 50%). In addition, the polarization-insensitive dispersion compensator 108 can eliminate power fluctuations associated with losses through polarization-sensitive components due to polarization shifts of the light beam 102.

[0070] The dispersion compensator 108 may operate as a transmissive element or a reflective element. A dispersion compensator 108 operating as a transmissive element may provide dispersed light as transmitted light and may have any structure known in the art. For example, a dispersion compensator 108 operating as a transmissive element may include a spatially varying refractive index variation in a pattern suitable for inducing diffraction. A dispersion compensator 108 operating as a reflective element may provide dispersed light as reflected light and may have any structure known in the art. For example, a dispersion compensator 108 operating as a reflective element may be formed as a substrate having surface features (e.g., a patterned surface) suitable for inducing diffraction. As an illustration, such a reflective dispersion compensator 108 may be formed as a semiconductor or metal surface having patterned surface features, which may be optionally coated with one or more additional layers (e.g., a dielectric layer and / or a metal layer) to control reflectivity. For some material types, a dispersion compensator 108 operating as a reflective element may be suitable for relatively higher power beams 102 compared to a transmissive element.

[0071] In some embodiments, dispersion compensator 108 provides a dispersion (D) having the same magnitude and opposite sign (eg, opposite sign) as AOD 106. DC ), which can be characterized by:

[0072]

[0073] For purposes of this disclosure, the dispersion compensator 108 is described as having an opposite dispersion to that of the AOD 106 when at least some operating conditions of the optical scanner 100 satisfy equation (4).

[0074] Figure 3A and 3B A dispersion compensator 108 is illustrated having an opposite dispersion to that of the AOD 106 for dispersion compensation. Figure 3A is a simplified schematic diagram of the AOD 106 exhibiting chromatic dispersion in accordance with one or more embodiments of the present disclosure. Figure 3B According to one or more embodiments of the present disclosure Figure 3A FIG. 1 is a simplified schematic diagram of a dispersion compensator 108 that provides opposite dispersion to the AOD 106 in FIG.

[0075] exist Figure 3A and 3B , a sign convention is used where angles measured in the clockwise direction are considered positive and angles measured in the negative direction are considered negative.

[0076] like Figure 3A, a light beam 102 incident on an AOD 106 exhibiting dispersion may be deflected at different angles based on wavelength. For example, light having a first wavelength (λ1) is deflected at a first deflection angle 214-1, and light having a second wavelength (λ2) is deflected at a second deflection angle 214-2, relative to the zero-order diffraction 208. Using the sign convention above, both the first deflection angle 214-1 and the second deflection angle 214-2 are positive angles. The dispersion of the AOD 106 may then correspond to D AOD =Δθ / (λ2-λ1), where Δθ corresponds to the difference between the second deflection angle 214-2 and the first deflection angle 214-1.

[0077] like Figure 3B , the dispersion compensator 108 providing the opposite dispersion to the AOD 106 can provide a deflection angle having the opposite sign to the AOD 106 for any sign convention. For example, Figure 3B Light having a first wavelength (λ1) is depicted being deflected at a first deflection angle 302-1 having the same magnitude but opposite sign as the first deflection angle 214-1 provided by the AOD 106 with respect to the zeroth order diffraction 208. Similarly, light having a second wavelength (λ2) is deflected at a second deflection angle 302-2 having the same magnitude but opposite sign as the second deflection angle 214-2 provided by the AOD 106 with respect to the zeroth order diffraction 304.

[0078] It is contemplated herein that the overall performance of an optical scanner 100 including an AOD 106 coupled to a passive dispersion compensator 108 having a fixed dispersion may vary based on operating conditions of the AOD 106, such as, but not limited to, the period (d) of the diffraction grating 206 in the AOD 106. As previously described herein, the deflection angle 214 of the light beam 102 by the AOD 106 may generally be controlled (e.g., during scanning) by adjusting the period (d) of the diffraction grating 206 by controlling the frequency of the drive signal 116 applied to the transducer 202. Thus, by controlling the frequency of the drive signal 116 within a commensurate range, the light beam 102 may be deflected within an operating range (e.g., a scanning range) of the deflection angle 214. However, adjusting the period (d) of the diffraction grating 206 may also change the dispersion (D ) of the AOD 106 for a particular wavelength. AOD Therefore, the fixed dispersion (D DC ) cannot fully compensate for the dispersion (D) of the AOD 106 for all frequencies of the driving signal 116. AOD ).

[0079] In some embodiments, the dispersion compensator 108 is tuned to the operating range of the AOD 106. For example, the dispersion compensator 108 may, but is not required to, be tuned to the center of the operating range of the AOD 106 (e.g., the center period (d) of the diffraction grating 206 associated with the corresponding center frequency of the drive signal 116). As an illustration, in the case of considering a dispersion compensator 108 formed with a DOE, the period of the DOE may be selected to be equal to the period (d) of the diffraction grating 206 in the AOD 106 associated with the center of the operating range of the AOD 106.

[0080] In this configuration, the dispersion compensator 108 can provide the most accurate dispersion compensation when the AOD 106 operates at the drive signal 116 frequency at the center of the operating range, while the accuracy of the dispersion compensation can decrease as the frequency of the drive signal 116 deviates from this center value. However, it is contemplated herein that in many applications, a performance degradation near the edge of the operating range may be acceptable. In some cases, the performance degradation near the edge of the operating range may be about 3 to 5 times.

[0081] Reference Figure 4 6 , the dispersion compensator 108 may be placed at any location suitable for compensating for the dispersion of the AOD 106 .

[0082] In some embodiments, the dispersion compensator 108 is positioned after the AOD 106 in the path of the light beam 102. In this way, the dispersion compensator 108 can at least partially remove the dispersion induced by the AOD 106. In some embodiments, the dispersion compensator 108 is positioned before the AOD 106 in the path of the light beam 102. In this way, the dispersion compensator 108 can introduce dispersion into the light beam 102 such that after the light beam 102 is deflected by the AOD 106, this dispersion is at least partially removed.

[0083] Figure 4 1 is a block diagram of an optical scanner 100 including a dispersion compensator 108 positioned before an AOD 106 in the path of a light beam 102 according to one or more embodiments of the present disclosure. In some embodiments, the dispersion compensator 108 is physically positioned near the AOD 106. For example, Figure 5 1 is a simplified schematic diagram of an optical scanner 100 including a dispersion compensator 108 before an AOD 106 in the path of a light beam 102 in accordance with one or more embodiments of the present disclosure.

[0084] like Figure 5 As shown in FIG. 1 , the dispersion (D DC ) may cause light of different wavelengths (e.g., λ1 and λ2) to reach the AOD 106 at different angles, making the dispersion (DAOD ) results in a constant deflection angle 214 for light of different wavelengths. In this way, spectral variations of the light beam 102 do not affect the deflection angle 214.

[0085] It is contemplated herein that placing the dispersion compensator 108 in close proximity to the AOD 106 may facilitate simple alignment and may not require additional components to provide dispersion compensation. Figure 5 , this configuration can result in a slight lateral displacement (Δl) 502 between light with different wavelengths exiting the AOD 106. In this way, light of different wavelengths can have the same deflection angle 214, but may not be co-linear. Instead, the resulting light beam 102 will be spatially dispersed across the beam profile. The magnitude of this lateral displacement (Δl) 502 depends on the dispersion (D DC ) and the distance between the dispersion compensator 108 and the AOD 106. Therefore, the effect of this lateral displacement (Δl) 502 can be reduced by placing the dispersion compensator 108 as physically close as possible to the AOD 106. In some applications, this lateral displacement (Δl) 502 can be relatively small compared to the size of the light beam 102 and can fall within the application tolerance.

[0086] It is further contemplated herein that in this configuration, the dispersion from the dispersion compensator 108 ( Figure 5 The zeroth order diffraction of the deflected beam 102 (not shown in the figure) may be incident on the AOD 106 and may thus be deflected by the AOD 106. In some cases, this zeroth order diffraction may be close to or partially overlap the deflected beam 102 (e.g., may be in the working area of ​​the AOD 106). However, the dispersion compensator 108 formed as a DOE may potentially be highly efficient so that the power of this zeroth order diffraction is negligible relative to the power of the deflected beam 102. For example, in simulations for wavelengths associated with the beam 102 from a CO2 laser, this zeroth order diffraction may have a power that is 0.2% less than the deflected beam 102.

[0087] In some embodiments, the optical scanner 100 includes one or more components between the dispersion compensator 108 and the AOD 106 , which may enable further manipulation of the light beam 102 .

[0088] Fig. 6A is a block diagram of an optical scanner 100 including an optical relay 602 to image the dispersion compensator 108 onto the AOD 106 according to one or more embodiments of the present disclosure. Figure 6B is a simplified schematic diagram of an optical scanner 100 including an optical relay 602 to image the dispersion compensator 108 onto the AOD 106 according to one or more embodiments of the present disclosure.

[0089] In some embodiments, the optical scanner 100 includes an optical relay 602 to generate an image of the dispersion compensator 108 (e.g., the operating plane of the dispersion compensator 108) onto the AOD 106 (e.g., the operating plane of the AOD 106). In this way, there is no Figure 5 The lateral displacement (Δl) 502 depicted in FIG. Instead, light of different wavelengths may be caused by dispersion D DC The optical repeaters 602 may be configured to maintain the dispersion (D ) induced by the dispersion compensator 108. DC ), so that light of different wavelengths incident on the AOD 106 is deflected at a common deflection angle 214.

[0090] The optical relay 602 may include any type of relay known in the art, and may include, but is not limited to, two or more lenses and / or focusing mirrors.

[0091] In some embodiments, the optical scanner 100 further includes a filter 604 formed of one or more elements (e.g., apertures, beam stops, or the like) to block undesirable light from the dispersion compensator 108, such as, but not limited to, undesirable diffraction orders (e.g., zeroth order diffraction or diffraction orders not associated with the light beam 102). Such elements may be positioned at any location suitable for blocking undesirable light, including, but not limited to, a pupil plane (e.g., a diffraction plane, a Fourier plane, or the like). For example, Figure 6B , the optical relay 602 may include a pair of lenses 606 or other focusing optics separated by twice their focal lengths (eg, in a 4-F arrangement) to produce a pupil plane 608 suitable for spatial filtering of undesired light.

[0092] The multi-directional operation of the optical scanner 100 is described in more detail according to one or more embodiments of the present disclosure.

[0093] The dispersion compensator 108 may be used for one-dimensional (1D) or two-dimensional (2D) scanning of one or more AODs 106. In general, when the dispersion (D DC ) has a dispersion (D) corresponding to the AOD 106 in the particular plane in which the beam 102 is scanned. AOD ) of the same magnitude but opposite sign (e.g. Figure 5 When the opposite angles are shown in the figure, dispersion compensation can be achieved.

[0094] Reference again Figure 2 and 3A , Figure 2 and 3AAOD 106 is depicted providing ID scanning in the YZ plane (eg, scan plane). Specifically, AOD 106 provides a diffraction grating 206 in the XY plane, where the grating direction (eg, periodicity direction) is along the Y direction and the thickness of the diffraction grating 206 is along the Z direction.

[0095] In some embodiments, the dispersion compensator 108 is arranged to provide dispersion (D) exclusively on the same axis as the AOD 106. DC ). Figure 7 1 is a conceptual diagram of the relative dispersion directions of a dispersion compensator 108 and a single AOD 106 arranged for 1D scanning in the YZ plane according to one or more embodiments of the present disclosure. In particular, Figure 7 The dispersion (D AOD ) is depicted as a vector pointing in the -Y direction, which is similar to Figure 2 and 3A Therefore, the light source 104 incident on the AOD 106 propagating along the YZ plane can be deflected in the -Y direction, where different wavelengths have different deflection angles 214, where the angular spread is determined by D AOD The value of is determined. Figure 7 Furthermore, the dispersion (D DC ) is depicted as a vector pointing in the +Y direction, which is similar to Figure 3B Therefore, the light source 104 incident on the dispersion compensator 108 propagating along the YZ plane can be deflected in the +Y direction, where different wavelengths have different deflection angles 214, where the angular spread is determined by D DC The value of is determined. Figure 7 As depicted in AOD and D DC When the magnitudes of are equal, the portions of the light beam 102 having different wavelengths are deflected at a common deflection angle 214 after propagating through both the dispersion compensator 108 and the AOD 106.

[0096] In some embodiments, the dispersion compensator 108 is arranged to provide dispersion (D) in a direction different from any particular AOD 106. DC In this way, a single dispersion compensator 108 can provide dispersion compensation for multiple AODs 106. Figure 8 1 is a conceptual diagram of the relative dispersion directions of the dispersion compensator 108 and two AODs 106 arranged for 2D scanning according to one or more embodiments of the present disclosure. In particular, Figure 8 Depict the two orthogonal scanning directions D AOD,1 and D AOD,2The associated dispersion may be provided by a single AOD 106 (eg, having multiple transducers 202) or two AODs 106, each providing a different deflection direction. Figure 8 Further description and suitable for simultaneously compensating D AOD,1 and D AOD,2 The dispersion (D DC ). For example, D DC Directed to D AOD,1 and D AOD,2 The angle between them is 135 degrees and equal to In this way, D DC The projections along the X-axis and Y-axis have the same value as D AOD,1 and D AOD,2 Both have the same magnitude but opposite signs.

[0097] Now generally refer to Figures 7 to 9 , the effect of polarization sensitivity of the dispersion compensator 108 and / or AOD 106 is described in more detail. Many AODs 106 are polarization sensitive and therefore benefit from or require a particular input polarization of the light beam 102. In this case, scanning along two directions (e.g., orthogonal directions) requires correspondingly rotating the polarization of the light beam 102 between the AODs 106. In addition, dispersion compensation can generally use multiple dispersion compensators 108 placed in front of the multiple AODs 106 and oriented at an angle relative to the AODs 106 (e.g., one per AOD 106, such as Figure 7 ) or a single dispersion compensator 108 (e.g., as Figure 8 to achieve this.

[0098] When the dispersion compensator 108 is also polarization sensitive, such that the transmittance and / or dispersion depends on the polarization of the beam 102, it may further be necessary to rotate the polarization of the beam 102 before or after the dispersion compensator 108 to provide the desired polarization for all elements. Figure 8 As described in the above, the polarization of the light beam 102 can be rotated to the orientation required by the polarization-sensitive dispersion compensator 108 (e.g., along the dispersion direction D DC ), then rotated to the orientation required by the first AOD 106 (e.g., along the Y direction), and then rotated to the orientation required by the second AOD 106 (e.g., along the X direction). In a general sense, the optical scanner 100 may include a wave plate or other suitable polarization rotation element for polarization control of the light beam 102.

[0099] However, it is contemplated herein that polarization management may be difficult or impractical for some applications. For example, providing arbitrary polarization rotation of the beam 102 from a CO2 laser may be difficult or impractical, particularly at relatively high powers (e.g., tens or hundreds of watts). In particular, wave plates (e.g., half-wave plates) suitable for operation in the 9 to 12 μm spectral range may be difficult to manufacture, costly, or may have an unsuitable damage threshold. Figure 8 In this case, the polarization of the light beam 102 is directed in the dispersion direction D of the dispersion compensator 108. DC Rotating 135 degrees about the Y-axis of the first AOD 106 may be difficult or impractical.

[0100] In some embodiments, the dispersion compensator 108 is polarization-insensitive such that the transmittance and / or dispersion does not depend on the polarization of the light beam 102 (at least within a selected tolerance). It is contemplated herein that such a polarization-insensitive dispersion compensator 108 may be well suited for, but is not limited to, providing simultaneous dispersion compensation for multiple AODs 106 (e.g., Figure 8 In this configuration, the dispersion compensator 108 may be oriented along any desired angle to provide dispersion compensation for the AOD 106 without having to adjust the polarization of the light beam 102 for efficient operation of the dispersion compensator 108.

[0101] continue Figure 8 , the polarization-insensitive dispersion compensator 108 will not require a specific polarization of the light beam 102 to operate within a selected tolerance. For example, the light beam 102 can be aligned along the Y axis before the dispersion compensator 108 and then incident on the first AOD 106 without further adjustment.

[0102] In applications that include two polarization-sensitive AODs 106 oriented to deflect in different (e.g., orthogonal) directions, the polarization of the light beam 102 must generally be rotated between the two AODs 106, regardless of the nature of the dispersion compensator 108. It is further contemplated herein that a 90 degree polarization rotation may be practical even when arbitrary polarization control (e.g., with a waveplate) is not possible or practical, such as in the case of a light beam 102 from a CO2 laser.

[0103] Fig. 9 is a block diagram of an optical scanner 100 having a polarization-insensitive dispersion compensator 108 arranged to provide dispersion compensation for two orthogonal polarization-sensitive AODs 106 in accordance with one or more embodiments of the present disclosure. Fig. 9 Also illustrated is an optical relay 602 between the dispersion compensator 108 and the first AOD 106 (e.g., as described with respect to Fig. 6A and 6B) to avoid any lateral displacement (Δl) 502 between different wavelengths in the beam 102 during scanning. Although the dispersion compensator 108 is Fig. 9 106, but this is merely illustrative and the dispersion compensator 108 may be positioned at any suitable location, including after or between the AODs 106.

[0104] In some embodiments, the optical scanner 100 includes a polarization rotator 902 between the first and second AODs 106 to rotate the polarization of the light beam 102 to be oriented as required by the second AOD 106. As an example, in an application with orthogonal AODs 106, the polarization rotator 902 may rotate the polarization of the light beam 102 by 90 degrees. In this way, a single polarization-insensitive dispersion compensator 108 may be used to achieve dispersion-compensated bidirectional scanning.

[0105] The polarization rotator 902 may include any component suitable for rotating the polarization of the light beam 102. In some embodiments, the polarization rotator 902 includes one or more rhombuses (e.g., Fresnel rhombuses) or prisms formed of a material that transmits the spectrum of the light beam 102 and designed to rotate the polarization of the light beam 102 by 90 degrees. For example, the polarization rotator 902 may include a half-wave (e.g., λ / 2) rhombus or two quarter-wave (e.g., λ / 4) rhombuses. As another example, the polarization rotator 902 may include one or more reflective phase retarders. The reflective phase retarders may include reflective materials that are designed to provide a phase shift between orthogonal polarization components after reflection, and may generally be designed for a wide range of wavelengths, powers, and phase retardation values. For example, quarter-wave (e.g., λ / 4) reflective phase retarders are commonly used in high power CO2 laser applications to convert a linearly polarized light beam into a circularly polarized light beam. The polarization rotator 902 may include two quarter wave reflective phase retarders to provide a half wave phase delay to rotate the polarization of the light beam 102 by 90 degrees. For example, orienting the first quarter wave reflective phase retarder so that the linear polarization direction of the light beam 102 is oriented at a 45 degree angle relative to the plane of incidence may provide a circularly polarized light beam 102. Similarly, orienting the second quarter wave reflective phase retarder at a 45 degree angle may provide the light beam 102 with a linear polarization that has been rotated 90 degrees relative to the input state. This polarization rotator 902 may maintain the scanning direction.

[0106] The multi-channel operation of the optical scanner 100 is described in more detail according to one or more embodiments of the present disclosure. In some embodiments, the optical scanner 100 includes multiple channels, each channel including at least one AOD 106. In addition, the AOD 106 in any particular channel can provide 1D or 2D scanning. In a general sense, the optical scanner 100 can include any number of AODs 106 in any number of channels.

[0107] In some embodiments, the optical scanner 100 includes a single dispersion compensator 108 to use, for example, but not limited to, Figure 7 and 8 The configuration depicted in provides dispersion compensation for all AODs 106. In some embodiments, the optical scanner 100 includes a plurality of dispersion compensators 108 positioned at any suitable location, including but not limited to locations before or within any channel.

[0108] The optical scanner 100 may utilize any one or more components to separate the light beam 102 into multiple channels. Fig.10 is a block diagram of an optical scanner 100 including a beam splitter 1002 to split a received light beam 102 into four channels, each channel including at least one AOD 106, according to one or more embodiments of the present disclosure. Fig.10 Further depicted is a configuration in which a single dispersion compensator 108 is positioned before the beam splitter 1002 to provide dispersion compensation for all of the AODs 106 .

[0109] In some embodiments, the dispersion compensator 108 formed as a DOE may further operate as a beam splitter to facilitate multi-channel operation. For example, the DOE may include a periodic structure along one or more directions to diffract the beam 102 into multiple diffraction orders. In this configuration, each diffraction order will then exhibit a dispersion (D DC ), as described throughout this disclosure.

[0110] Fig.11 is a block diagram of an optical scanner 100 including a dispersion compensator 108 that provides both dispersion compensation and beam splitting, according to one or more embodiments of the present disclosure.

[0111] In this paper, the dispersion (D DC ) may vary for different diffraction orders. Therefore, in some embodiments, the dispersion compensator 108 formed as a DOE may diffract the light beam 102 into multiple light beams having the same diffraction order, such that the dispersion (D) of each light beam is DC ) are the same in magnitude. For example, the dispersion compensator 108 formed as a DOE may separate the incident light beam 102 into two first-order diffraction beams: a +1-order diffraction beam having a dispersion vector along the +Y axis and a -1-order diffraction beam having a dispersion vector along the -Y axis. As another example, the dispersion compensator 108 formed as a DOE may separate the incident light beam 102 into four first-order diffraction beams: a +1-order diffraction beam having a dispersion vector along the +Y axis, a -1-order diffraction beam having a dispersion vector along the -Y axis, a +1-order diffraction beam having a dispersion vector along the +X axis, and a -1-order diffraction beam having a dispersion vector along the -X axis.

[0112] Reference Fig.12 , the optical scanner 100 may be adapted to operate within a larger system, such as, but not limited to, a laser material processing system. Fig.12 is a block diagram of a system 1200 including an optical scanner 100 according to one or more embodiments of the present disclosure.

[0113] In some embodiments, the system 1200 includes a stage 1202 to hold a sample 1204. In some embodiments, the system 1200 includes one or more focusing optics 1206 to focus the light beam 102 from the optical scanner 100 onto the sample 1204. Thus, the system 1200 can direct or scan the light beam 102 across the sample 1204 in any pattern, wherein the AOD 106 within the optical scanner 100 is adjusted to compensate for spectral variations of the light beam 102 so that the position of the light beam 102 on the sample 1204 can be consistent regardless of spectral variations.

[0114] The focusing optics 1206 may include any number or type of focusing optics suitable for focusing the light beam 102 onto the sample 1204. In some embodiments, the focusing optics 1206 include a f-focus lens to provide consistent focusing of the light beam 102 across a flat plane and linear displacement across the sample 1204 depending on the input angle (e.g., associated with the deflection angle of the light beam 102 from the optical scanner 100).

[0115] In some embodiments, system 1200 includes one or more additional components to provide additional control over the position of beam 102 on sample 1204. For example, stage 1202 may include a translation stage having one or more linear or angular actuators to adjust the position of sample 1204 along any number of degrees of freedom. As another example, system 1200 may include additional deflectors 1208, such as, but not limited to, Fig.12 In this way, the scanning range can be increased beyond the range of the optical scanner 100. For example, Fig.12 A mechanical beam scanner using a stage 1202 or galvanometer as depicted in FIG. 1 may provide a larger scanning range than the optical scanner 100 , but with a relatively slower scanning rate.

[0116] The system 1200 may further include any number of additional optical devices to control various aspects of the light beam 102, such as, but not limited to, polarizers, spectral filters, spatial filters, or apodizers. Although not explicitly stated, such additional optical devices may be distributed throughout the system 1200 and / or at any suitable locations within the optical scanner 100.

[0117] In addition, if Fig.12, controller 110 may be communicatively coupled with any component in system 1200. In this manner, controller 110 may provide drive signals to any component (e.g., drive signal 116 and / or additional drive signal 1110), receive data from any component, or the like.

[0118] Reference Fig.13 , Fig.13 is a flow chart illustrating steps performed in a method 1300 for passive dispersion compensation of an acousto-optic deflector according to one or more embodiments of the present disclosure. Applicants should note that the embodiments and implementation techniques previously described herein in the context of the optical scanner 100 should be interpreted as extending to the method 1300. However, it should be further noted that the method 1300 is not limited to the architecture of the optical scanner 100.

[0119] In some embodiments, the method 1300 includes a step 1302 of deflecting the light beam 102 along one or more scanning directions with the AOD 106 , wherein the deflection angle 214 of the light beam 102 from the AOD 106 may be controlled by one or more drive signals applied to the AOD 106 .

[0120] In some embodiments, method 1300 includes step 1304 of dispersing light beam 102 with a dispersion compensator 108, wherein the dispersion of the dispersion compensator 108 at least partially compensates for the dispersion of the AOD 106, such that under a particular configuration of one or more drive signals, a deflection angle 214 of the light beam 102 from the AOD 106 and the dispersion compensator 108 is constant within a tolerance (e.g., a first tolerance) for a wavelength of the light beam 102 within a wavelength range, and wherein at least one of the dispersion of the dispersion compensator 108 or the transmittance of the dispersion compensator 108 is independent of the polarization of the light beam 102 within a tolerance (e.g., a second tolerance).

[0121] For example, as described with respect to optical scanner 100, dispersion compensator 108 may include any component or combination of components suitable for providing dispersion (eg, angular dispersion) suitable for at least partially compensating for the dispersion of AOD 106, and may include, but is not limited to, a DOE or a prism.

[0122] The objects described herein sometimes illustrate different components contained in or connected to other components. It should be understood that such depicted architectures are exemplary only, and in fact many other architectures that realize the same functionality can be implemented. In a conceptual sense, any arrangement of components to realize the same functionality is effectively "associated" so that the desired functionality is realized. Therefore, without considering the architecture or intermediate components, any two components combined to realize a specific functionality herein can be considered to be "associated" with each other so that the desired functionality is realized. Similarly, any two components so associated can also be considered to be "connected" or "coupled" to each other to realize the desired functionality, and any two components that can be so associated can also be considered to be "coupleable" to each other to realize the desired functionality. Specific examples that can be coupled include but are not limited to components that can physically interact and / or physically interact and / or components that can wirelessly interact and / or wirelessly interact and / or components that can logically interact and / or logically interact.

[0123] It is believed that the present disclosure and its many attendant advantages will be appreciated from the foregoing description, and it will be appreciated that various changes may be made to the form, construction and arrangement of components without departing from the disclosed object or sacrificing all of its significant advantages. The described form is illustrative only, and it is intended that such changes be covered and included by the appended claims. Furthermore, it should be understood that the invention is defined by the appended claims.

Claims

1. An optical scanner, comprising: one or more acousto-optic deflectors (AODs) configured to deflect a light beam along one or more scanning directions, wherein a deflection angle of the light beam from the one or more AODs can be controlled by one or more drive signals applied to the one or more AODs; and A dispersion compensator, wherein the dispersion of the dispersion compensator at least partially compensates for the dispersion of the one or more AODs to provide, under a specific configuration of the one or more drive signals, the deflection angle of the light beam by the one or more AODs and the dispersion compensator is constant within a first tolerance for the wavelength of the light beam within a wavelength range, wherein at least one of the dispersion of the dispersion compensator or the transmittance of the dispersion compensator is independent of the polarization of the light beam within a second tolerance.

2. The optical scanner according to claim 1, wherein the dispersion compensator comprises: Diffractive optical element.

3. The optical scanner of claim 1 , wherein the dispersion compensator comprises: Prism.

4. An optical scanner according to claim 1, wherein the magnitude of the dispersion of any one of the one or more AODs varies within an operating range associated with a corresponding one of the one or more drive signals, and wherein the magnitude of the dispersion projected by the dispersion compensator along the dispersion direction associated with a specific one of the one or more AODs is equal to the magnitude of the dispersion of the specific one of the one or more AODs for at least one value of the corresponding operating range.

5. The optical scanner of claim 1, wherein the dispersion compensator is positioned before the one or more AODs.

6. The optical scanner of claim 1, wherein the dispersion compensator is positioned after the one or more AODs.

7. The optical scanner of claim 1, wherein the dispersion compensator is positioned adjacent to one of the one or more AODs.

8. The optical scanner according to claim 1, further comprising: An optical relay is interposed between the dispersion compensator and at least one of the one or more AODs.

9. The optical scanner of claim 8, wherein the dispersion compensator comprises a diffractive optical element (DOE), wherein the optical scanner further comprises a filter to block at least a zeroth order diffraction from the DOE.

10. The optical scanner of claim 1, wherein the one or more AODs comprise a single AOD, wherein the one or more scanning directions of the one or more AODs comprise a single scanning direction.

11. The optical scanner of claim 1, wherein the one or more scanning directions of the one or more AODs include a first scanning direction and a second scanning direction.

12. The optical scanner of claim 11, wherein the one or more AODs include two AODs, wherein the first scanning direction and the second scanning direction are orthogonal, wherein the optical scanner further comprises: A polarization rotator is interposed between the two AODs to rotate the polarization of the light beam by 90 degrees.

13. The optical scanner according to claim 12, wherein the polarization rotator comprises: At least one of one or more reflective phase retarders or one or more rhombohedrons.

14. The optical scanner of claim 1, wherein the dispersion compensator is a transmissive element.

15. The optical scanner of claim 1, wherein the dispersion compensator is a reflective element.

16. The optical scanner of claim 1, wherein the light beam has a wavelength in the range of 9 to 12 microns.

17. A method comprising: deflecting a light beam along one or more scanning directions using an acousto-optic deflector (AOD), wherein the deflection angle of the light beam from the AOD can be controlled by one or more drive signals applied to the AOD; The light beam is dispersed by a dispersion compensator, wherein the dispersion of the dispersion compensator at least partially compensates for the dispersion of the AOD, so that under a specific configuration of the one or more driving signals, the deflection angle of the light beam from the AOD and the dispersion compensator is constant within a first tolerance for the wavelength of the light beam within a wavelength range, wherein at least one of the dispersion of the dispersion compensator or the transmittance of the dispersion compensator is independent of the polarization of the light beam within a second tolerance.

18. The method according to claim 17, further comprising: The dispersive element is positioned adjacent to the AOD.

19. The method of claim 17, further comprising: The light beam is relayed between the dispersion compensator and the AOD using an optical relay.

20. The method of claim 17, further comprising: wherein the dispersion compensator comprises a diffractive optical element (DOE), wherein the method further comprises: At least the zeroth order diffraction from the DOE is filtered.

21. The method of claim 17, wherein the light beam has a wavelength in the range of 9 to 12 microns.

22. An optical scanner comprising: a dispersion compensator formed as a diffractive optical element (DOE) configured to diffract a light beam into two or more diffracted light beams along two or more directions, wherein at least one of a dispersion of the dispersion compensator or a transmittance of the dispersion compensator is independent of a polarization of the light beam within a first tolerance; Two or more acousto-optic deflectors (AODs) for receiving the two or more diffracted light beams and deflecting the two or more diffracted light beams, wherein the deflection angles of the diffracted light beams from the two or more AODs can be controlled by driving signals applied to the two or more AODs, wherein the dispersion of the dispersion compensator at least partially compensates for the dispersion of the two or more AODs to provide, under a specific configuration of the one or more driving signals, the deflection angles of the diffracted light beams by the dispersion compensator and the two or more AODs are constant within a second tolerance for the wavelength of the light beams within a wavelength range.

23. The optical scanner of claim 22, wherein each of the two or more diffracted beams corresponds to a first order diffraction of the DOE.

24. The optical scanner of claim 22, wherein the two or more diffracted beams comprise: Two diffracted beams.

25. The optical scanner of claim 22, wherein the two or more diffracted beams comprise: Four diffracted beams.

26. The optical scanner of claim 22, wherein the DOE is a transmissive element.

27. The optical scanner of claim 22, wherein the DOE is a transmissive element.

28. The optical scanner of claim 22, wherein the light beam has a wavelength in the range of 9 to 12 microns.

29. A system comprising: a light source configured to generate a light beam; A scanner comprising: one or more acousto-optic deflectors (AODs) configured to deflect a light beam along one or more scanning directions, wherein a deflection angle of the light beam from the one or more AODs can be controlled by one or more drive signals applied to the one or more AODs; and a dispersion compensator, wherein the dispersion of the dispersion compensator at least partially compensates for the dispersion of the one or more AODs, such that under a specific configuration of the one or more drive signals, the deflection angle of the light beam by the dispersion compensator and the one or more AODs is constant within a first tolerance for a wavelength of the light beam within a wavelength range, wherein at least one of the dispersion of the dispersion compensator or the transmittance of the dispersion compensator is independent of the polarization of the light beam within a second tolerance; and One or more focusing optics configured to focus the light beam deflected by the one or more AODs onto a sample.

30. The system of claim 29, wherein the light beam has a wavelength in the range of 9 to 12 microns.

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