Optomechanical assembly for temperature-robust laser beam combining and delivery

Abstract

An optomechanical assembly (100) for temperature-robust laser beam processing includes a base plate (110) and an optical plate (130). The base plate includes a source region (112) for housing a source (160) of a laser beam and a light processing region (114) located away from the source region and including a first anchor point (116) and a second anchor point (118). The optical plate is disposed in the light processing region and includes a first portion (132) and a second portion (134) and a flexible link (136) interconnecting the first and second portions. The first and second portions are fixed to the base plate at the first and second anchor points, respectively. The flexible link allows for a thermally induced change in distance between the first and second anchor points in the presence of different thermal expansions of the optical plate and the base plate. The assembly further includes a linear arrangement of optical elements (142) for manipulating the laser beam from the laser source. Each optical element is rigidly coupled with the first portion (132). A coefficient of thermal expansion (CTE) of the optical plate (130) is matched with a CTE of the optical elements (142).

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Patent Application Serial No. 63 / 143,670, filed January 29, 2021, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to laser beam shaping and guiding in the presence of temperature variations, and more particularly to optomechanical components suitable for reducing temperature-induced variations in the spatial characteristics of a laser beam. Background Technology

[0004] Lasers with high spatial coherence can be generated. High spatial coherence provides a level of spatial control that is impossible to achieve using incoherent light sources such as incandescent bulbs or even light-emitting diodes. For example, the laser beam can be tightly focused or formed into a well-collimated beam, thus maintaining a relatively small beam diameter over long distances. Therefore, the laser beam can be directed to a target location with very high precision, and furthermore, with well-defined lateral dimensions and convergence / divergence. However, this spatial control can be affected by variations in ambient temperature. When ambient temperature changes, or when heat is generated by internal components of the laser system, the optics used to manipulate the laser beam may expand or contract, and their positions may shift due to the thermal expansion or contraction of the structures supporting the optics. These temperature effects can cause various problems, such as laser beam pointing errors, collimation losses, and longitudinal focus shifts due to variations in convergence / divergence. Here, the terms "lateral" and "longitudinal" are defined relative to the local propagation direction of a reference laser beam.

[0005] Many laser-based technologies rely on the stable spatial properties of a laser beam. These technologies can utilize various methods to stabilize the spatial laser beam characteristics in the presence of temperature variations. The temperature of the laser system or one or more of its key subsystems can be actively controlled to maintain a constant temperature across a wide temperature range. The materials for the optical elements and / or support structures can be limited to those with relatively low coefficients of thermal expansion. Another option is to actively control certain optical elements to correct for temperature-induced variations. For example, this can be achieved by altering the laser beam pointing or laser beam parameters (e.g., waist size, waist position, and Rayleigh range).

[0006] Modern laser-based flow cytometry is an example of a technique requiring stable spatial characteristics of the laser beam. In flow cytometry, a laser beam is focused onto a flowing sample. Typically, as fluorescently labeled cells in the flowing sample pass through the laser beam focus, fluorescence, forward-scattered laser light, and side-scattered laser light are detected independently, allowing cell identification by their fluorescence properties and size. The lateral profile of the laser beam at its focus can be narrower in the dimension parallel to the sample flow path and finer in the dimension perpendicular to the sample flow path, with the narrow dimension being as small as approximately 10–15 micrometers. Reliable and accurate cell identification depends on the stability of the laser beam focus. Most commercially available flow cytometers are equipped with multiple lasers, each with a different wavelength, to be compatible with many different fluorophores and to process samples labeled with different combinations of fluorophores. Until recently, different laser beams intersected the sample flow path at different locations, and each laser channel had its own independent side-scattered fluorescence detection system. However, recently, so-called spectroscopic flow cytometers have been developed. Spectroscopic flow cytometers propagate all laser beams together and focus them onto the same plane intersecting the sample flow path. Compared to traditional flow cytometry, spectroscopic flow cytometry uses a single-sided scattering fluorescence detection system shared by all laser channels. This fluorescence detection system uses a spectrometer to distinguish different wavelengths. Invention Overview

[0008] This document discloses an optomechanical assembly for temperature-robust laser beam delivery. Current optomechanical assemblies employ a two-pronged approach to reduce the impact of temperature variations on sub-assemblies used to manipulate the laser beam: (1) the sub-assemblies are made of materials with relatively low coefficients of thermal expansion, and (2) mechanical decoupling between the sub-assemblies and the supporting substrate prevents thermal expansion or contraction of the substrate from forcing the sub-assemblies to expand, contract, or deform. For the remainder of this disclosure, unless otherwise stated, the term expansion encompasses both positive and negative expansion (i.e., contraction). The temperature of the optomechanical assembly can respond to changes in ambient temperature or as heat is generated from an internal source (e.g., a laser). Flow cytometers can utilize the currently disclosed assembly for temperature-robust laser beam delivery to maintain a stable laser beam focus at the intersection with the sample flow path.

[0009] The same principle applies to optomechanical components used for the temperature-robust combination and delivery of multiple laser beams. In such beam-combining components, multiple distinct sub-components made of a material with a relatively low coefficient of thermal expansion are supported by a common substrate. Each sub-component manipulates a different, corresponding laser beam before it is combined with other laser beams to form a composite laser beam. Mechanical decoupling between each sub-component and the supporting substrate prevents thermal expansion of the substrate from forcing the sub-component to expand or deform. The currently disclosed beam-combining components are suitable for incorporation into spectroscopic flow cytometers, where they can maintain a stable focus of the composite multicolor laser beam at the intersection with the sample flow path.

[0010] On one hand, an optomechanical assembly for temperature-robust laser beam processing includes a substrate. The substrate includes a source region for housing a laser beam source and an optical processing region positioned away from the source region and including a first anchor point and a second anchor point. The assembly also includes an optical plate disposed in the optical processing region. The optical plate includes a first portion and a second portion, and a flexible connector interconnecting the first and second portions. The first and second portions are fixed to the substrate at the first and second anchor points, respectively. The flexible connector allows for thermally induced changes in the distance between the first and second anchor points in the presence of different thermal expansions in the optical plate and the substrate. Furthermore, the assembly includes a series of linearly arranged optical elements for manipulating a laser beam from a laser source. Each optical element is rigidly coupled to the first portion of the optical plate and arranged along the propagation axis of the laser beam, which coincides with the line between the first and second anchor points. The coefficient of thermal expansion (CTE) of the optical plate (a) matches the CTE of the optical elements to within 20%; (b) is lower than the CTE of the substrate.

[0011] On the other hand, a temperature-robust optomechanical assembly for laser beam combining includes a substrate having orthogonal longitudinal and lateral dimensions and comprising a series of source regions. The source regions are distributed along the lateral dimension and each is configured to house a laser source for generating a corresponding laser beam. The assembly also includes a sequence of corresponding optical sub-assemblies offset from the source region sequence in the longitudinal dimension. Each optical sub-assembly includes an optical plate fixed to the substrate. Each optical plate includes at least one flexure element to accommodate different thermal expansions of the optical plate and the substrate. At least one optical sub-assembly includes a linearly arranged series of optical elements, which (a) are rigidly coupled to the optical plate, (b) are characterized by a coefficient of thermal expansion (CTE) matching the CTE of the optical plate to within 20%, and (c) are configured to manipulate laser beams received from the corresponding source regions. The assembly also includes a mirror rigidly coupled to the optical plate of a first optical sub-assembly. Additionally, for each of one or more subsequent optical sub-assemblies, the assembly includes a corresponding beam combiner rigidly coupled to the optical plates of one or more subsequent optical sub-assemblies. The mirror and the one or more beam combiners are cooperatively configured to continuously combine laser beams. Attached Figure Description

[0012] The accompanying drawings, which are incorporated in and constitute a part of this specification, schematically illustrate preferred embodiments of the invention and, together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.

[0013] Figure 1 and Figure 2 An optomechanical assembly for temperature-robust transmission of a laser beam, according to an embodiment, is shown.

[0014] Figure 3 An optomechanical assembly for temperature-robust laser beam combination is shown according to an embodiment.

[0015] Figure 4 An optical plate according to an embodiment is shown, which is configured to house a series of optical elements and decouple these optical elements from the thermal expansion of the substrate supporting the optical plate.

[0016] Figure 5 and Figure 6 Another optical plate according to an embodiment is shown, comprising two flexures for decoupling a series of optical elements from the thermal expansion of a supporting substrate.

[0017] Figure 7 The direct integration of optical elements with an optical plate according to the embodiment is shown.

[0018] Figure 8 The optical element is shown to be indirectly coupled to the optical plate via a mounting component according to the embodiment.

[0019] Figure 9 An optical element according to an embodiment is shown to be indirectly coupled to an optical plate via two pillars that hold the optical element above the optical plate. Invention Details

[0021] Referring now to the accompanying drawings, the same parts are indicated by the same reference numerals. Figure 1 and Figure 2 This is a top view of an optomechanical assembly 100 for temperature-robust delivery of a laser beam. Assembly 100 can be advantageously implemented in a flow cytometer to deliver a laser beam to a sample flow path in a temperature-robust manner. Assembly 100 includes a substrate 110 and a sub-assembly 120 mounted on the substrate 110. Sub-assembly 120 is mounted to the substrate 110 in a light processing region 114. Sub-assembly 120 is configured to manipulate a laser beam 190 received from a laser source 160, which is mounted on the substrate 110 located in a source region 112. Assembly 100 may or may not include the laser source 160. Figure 1 and Figure 2 The state of component 100 at two different temperatures is shown. Figure 2 The relevant temperature is higher than that of Figure 1 The relevant temperature.

[0022] The shape of the substrate 110 can be consistent with Figure 1 and 2 The shapes shown are different. For example, as... Figure 1 and 2 As shown, it is not rectangular. The substrate 110 may include a plurality of through holes for mounting the component 100 to the support. Figure 1 Four exemplary through holes 111 are marked in the middle.

[0023] Subassembly 120 includes an optical plate 130 mounted to a substrate 110, and a series of optical elements 140 and 142 mounted to a portion 132 of the optical plate 130. Optical elements 140 and 142 are used to manipulate a laser beam 190 to generate a manipulated laser beam 192. Optical elements 140 and 142 are arranged in series along the laser beam 190 and include a final optical element 140 and one or more preceding optical elements 142. Figure 1 and Figure 2 In the depicted embodiment, optical element 140 is a mirror, and subassembly 120 includes three front optical elements 142(ac), wherein elements 142(a) and 142(b) are lenses, and element 142(c) may be a waveplate, polarizer, or filter. In this depicted embodiment, lenses 142(a) and 142(b) may form a telescope configured to change the size of a collimated laser beam. Subassembly 120 may alternatively be used with... Figure 1 and Figure 2 It is achieved by using different series of optical elements described in the text.

[0024] Optical elements 140 and 142 are rigidly coupled to a portion 132 of optical plate 130. Each of optical elements 140 or 142 may be coupled directly or indirectly to optical plate 130 via one or more mounting elements. When coupled indirectly to optical plate 130 via a mounting element, the optical element is rigidly coupled to the mounting element, the mounting element is rigidly coupled to optical plate 130, and the mounting element itself is rigid. The coefficient of thermal expansion (CTE) of optical plate 130 is matched to within 20% of the CTE of optical elements 140 and 142 to prevent significant differences between the thermal expansion of optical plate 130 and the thermal expansion of optical elements 140 and 142, and, for example, to prevent the bond from breaking during thermal expansion. For the same reason, the CTE of any mounting element used to couple optical elements 140 and 142 to optical plate 130 is also matched to within 20% of the CTE of optical elements 140 and 142. Such a mounting element may be made of the same material as optical elements 140 and 142.

[0025] Furthermore, the CTE of optical plate 130 and optical elements 140 and 142 is relatively low to limit changes in the relative positions of optical elements 140 and 142 caused by thermal expansion of optical plate 130 and / or optical elements 140 and 142 themselves. In one embodiment, the CTE of optical plate 130 and the CTE of each optical element 140 and 142 are less than 10. -5 K -1 .

[0026] In one embodiment, optical plate 130 is made of metal, and optical elements 140 and 142 are made of glass. In this embodiment, any mounting hardware used to attach one or more of optical elements 140 and 142 to optical plate 130 may also be made of metal or glass. Optical plate 130 may be made of titanium or a titanium alloy, such as α-β titanium alloy (e.g., Ti-6Al-4V). Optical elements 140 and 142 may be made of borosilicate glass, such as Schott N-BK7.

[0027] In addition to portion 132, optical plate 130 also includes portion 134 and a flexible connector 136 interconnecting portions 132 and 134. Portions 132 and 134 are secured to substrate 110 at corresponding anchor points 116 and 118. Anchor points 116 and 118 are located further away from and closer to source region 112, respectively. In one embodiment, portion 132 is secured to anchor point 116 of substrate 110 by fastener 156 passing through a hole in portion 132, and portion 134 is secured to anchor point 118 of substrate 110 by fastener 158 passing through a hole in portion 134. The flexible connector may include or consist of one or more flexures, each flexure interconnecting portions 132 and 134 while allowing variation in the distance between portions 132 and 134.

[0028] like Figure 1 and Figure 2 As shown by the differences, in the presence of different thermal expansions between substrate 110 and sub-assembly 120, the flexible connector 136 allows for thermally induced changes in the distance between anchor points 116 and 118. Significantly different thermal expansions may occur when the CTE of substrate 110 and the CTE of the optical plate differ by more than, for example, 20%—for instance, when the CTE of substrate 110 is at least twice the CTE of optical plate 130. Figure 1 At a lower temperature, substrate 110 has a length of 110L, portion 132 has a length of 132L, and portions 132 and 134 are separated by a distance of 136L. The lengths 110L, 132L, and distance 136L are measured in a dimension parallel to the propagation axis of the laser beam 190 between source region 112 and light processing region 114. (Substrate 110 may or may not have a side parallel to the length 110L.) Figure 2At higher temperatures, substrate 110 has a length of 110L', portion 132 has a length of 132L', and portions 132 and 134 are separated by a distance of 136L'. Since the CTE of optical plate 130 is less than the CTE of substrate 110, the relative length increase of portion 132, i.e., (132L'-132L) / 132L, is less than the relative length increase of substrate 110, i.e., (110L'–110L) / 110L. Anchor points 116 and 118 move with the thermal expansion of substrate 110, and the difference in the relative length increase between portion 132 and substrate 110 is adjusted by flexible connector 136. Figure 1 and Figure 2 As shown, in Figure 2 At higher temperatures, the distance 136L' between parts 132 and 134 exceeds the distance between them. Figure 1 The distance 136L between parts 132 and 134 at a lower temperature.

[0029] With the flexible connector 136, the relative positions of optical elements 140 and 142 are unaffected by the thermal expansion of substrate 110, at least as long as the variation in the spacing between anchor points 116 and 118 is within the dynamic range of the flexible connector 136. The relative positions of optical elements 140 and 142 may still be affected by their inherent thermal expansion and the thermal expansion of part of 132. Without the flexible connector 136, substrate 110 and optical plate 130 would essentially act as bimetallic strips by being fixed to each other at anchor points 116 and 118. Therefore, without the flexible connector 136, the different thermal expansion of substrate 110 and optical plate 130 would result in deformations that alter the relative positions of optical elements 140 and 142, leading to deformation and / or misalignment of the laser beam 190.

[0030] In one embodiment, the CTE of optical plate 130 and the CTE of optical elements 140 and 142 are lower than the CTE of substrate 110. For example, substrate 110 may be made of aluminum or an aluminum alloy (e.g., 6061-T6), while optical plate 130 may be made of titanium or a titanium alloy, as described above. In this embodiment, the thermal expansion of optical plate 130 and substrate 110 is different, but flexible connector 136 accommodates the different thermal expansions and makes the relative position of optical elements 140 and 142 robust to the thermal expansion of substrate 110. Compared to assemblies where optical elements 140 and 142 are directly mounted to substrate 110, assembly 100 thus reduces the thermal expansion effects on the relative position of optical elements 140 and 142. The dynamic range of flexible connector 136 allows the spacing between anchor points 116 and 118 to vary up to at least several micrometers, for example, up to at least 5 micrometers.

[0031] Without departing from the scope of the invention, the CTE of substrate 110 may be similar to or less than the CTE of optical plate 130 and optical elements 140 and 142.

[0032] exist Figure 1 and Figure 2 In the illustrated embodiment, anchor points 116 and 118 are located on a line coinciding with the linear propagation axis of the laser beam 190. In another embodiment, one or both anchor points 116 and 118 are offset from this axis. Additionally, without departing from the scope of the invention, subassembly 120 may be configured such that the propagation path of the laser beam 190 between the optical elements mounted to portion 132 is folded, rather than as... Figure 1 and Figure 2 The linear propagation path is shown.

[0033] exist Figure 1 and Figure 2 In the illustrated embodiment, each of portions 132 and 134 is secured to the substrate 110 at a single anchor point. Without departing from the scope of the invention, since optical elements 140 and 142 are mounted to portion 132, portion 134 can be secured to the substrate 110 at two or more anchor points (and thus potentially subject to the thermal expansion of the substrate 110). For example, portion 134 can be secured to the substrate 110 at two anchor points 118 symmetrically offset from the linear propagation axis of the laser beam.

[0034] As the substrate 110 expands, the distance between portion 132 and source region 112 changes. As a result, when the substrate 110 expands, the point where optical elements 140 and 142 intersect with the laser beam 190 shifts along the propagation axis of the laser beam 190. In one scenario, the laser beam 190 is collimated (or at least approximately collimated) at the input of subassembly 120 such that the characteristics of the laser beam 192 are insensitive (or at least approximately insensitive) to this change in the distance between portion 132 and source region 112.

[0035] Optical element 140 defines an origin 198 from which subassembly 120 emits a manipulated laser beam 192 for direct use or for further processing outside subassembly 120. To stabilize the position of origin 198 relative to substrate 110, optical element 140 may be positioned close to anchor point 116 such that thermal expansion of portion 132 has minimal impact on the position of optical element 140 and origin 198 relative to anchor point 116. In one embodiment, optical element 140 is positioned such that origin 198 is directly above anchor point 116. Element 140 may be a mirror arranged to direct the manipulated laser beam 192 at a non-zero angle (e.g., approximately 90 degrees) to the propagation axis of the laser beam 190 between source region 112 and subassembly 120. Figure 1 and Figure 2 (As shown) Subassembly 120 is guided out. In this embodiment, the positioning of the optical element 140 near the anchor point 116 minimizes the lateral translation of the manipulated laser beam 192 caused by the thermal expansion of the portion 132. Specifically, it is contemplated that the incident and reflection points of the laser beam 190 on the optical element 140 are positioned directly above the anchor point 116 to eliminate this lateral translation. Furthermore, in this embodiment, the substrate 110 may have through-holes (for mounting the assembly 100 to the support) that are substantially aligned with the propagation axis of the manipulated laser beam 192 to increase temperature robustness. For example, the anchor point 116 and the two through-holes 111 of the substrate 110 may be located on a line that coincides with or is parallel to and close to the propagation axis of the manipulated laser beam.

[0036] The optical plate 130 can be integrally formed. In one such embodiment, the flexible connector 136 is in the form of one or more relatively thin and flexible connectors between portions 132 and 134. In another such embodiment, the flexible connector 136 is in the form of one or more connectors between portions 132 and 134, wherein the contact area between each connector and each of portions 132 and 134 has a small cross-sectional area to allow flexing in the region near the contact area.

[0037] In one application scenario, the flow cytometer includes component 100 to generate and shape a manipulated laser beam 192 for interrogation of a sample. In this scenario, the flow cytometer also includes a focusing lens that focuses the manipulated laser beam 192 onto the sample flow path. This focusing lens may be mounted on substrate 110 or external to component 100.

[0038] Figure 3 This is a top view of an optomechanical assembly 300 for temperature-robust laser beam combination. Assembly 300 is an extension of assembly 100, wherein a substrate supports a plurality of sub-assemblies 120 configured to manipulate different corresponding laser beams 190 and to continuously combine the manipulated laser beams. Assembly 300 can be advantageously implemented in a spectroscopic flow cytometer to combine multiple laser beams of different colors and deliver the resulting composite laser beam to the sample flow path in a temperature-robust manner.

[0039] Component 300 includes a substrate 310. Substrate 310 is an extension of substrate 110 and includes a plurality of source regions 112 and corresponding plurality of light processing regions 114. Each source region 112 is configured to accommodate a corresponding laser source 160. Component 300 may or may not include a laser source 160. Component 300 includes a plurality of sub-components 120, each sub-component 120 mounted in a different corresponding light processing region 114 to manipulate a laser beam 190 received from the laser source 160 of the corresponding source region 112. Each sub-component 120 of component 300 is constructed within the corresponding light processing region 114 of substrate 310 in the same manner as the sub-components 120 of component 100 are constructed within the light processing region 114 of substrate 110.

[0040] exist Figure 3 In the illustrated embodiment, component 300 includes three source regions 112 (1-3) and three light processing regions 114 (1-3). Each light processing region 114(i), i∈{1,2,3}, includes a sub-component 120(i) configured to manipulate a laser beam 190(i) received from a laser source 160(i) located in the source region 112. The last optical element 140 of sub-component 120(1) is implemented as a mirror 340M, which guides the manipulated laser beam 192(1) generated by the optical element 142 of sub-component 120(1) toward the last optical element 140 of sub-component 120(2). The last optical element 140 of sub-assembly 120(2) is implemented as a beam combiner 340C, which combines the manipulated laser beam 192(1) with the manipulated laser beam 192(2) generated by the optical element 142 of sub-assembly 120(2) to form a composite laser beam 394(2). The beam combiner 340C of sub-assembly 120(2) directs the composite laser beam 394(2) toward the last optical element 140 of sub-assembly 120(3). The last optical element 140 of sub-assembly 120(3) is implemented as a beam combiner 340C, which combines the composite laser beam 394(2) with the manipulated laser beam 192(3) generated by the optical element 142 of sub-assembly 120(3) to form a composite laser beam 394(3). Therefore, the mirror 340M of component 300 and each beam combiner 340C cooperate to serially combine the manipulated laser beams 192(1), 192(2) and 192(3) into a single composite laser beam 394(3).

[0041] In another implementation scheme, Figure 3As not shown, component 300 omits the intermediate sub-component 120 (2) and includes only a first sub-component 120 (1) and a last sub-component 120 (3) for combining two laser beams. Similarly, a sequence of sub-components 120 in component 300 may include more than one sub-component 120 between the first and last sub-components 120 for the serial combination of more than three laser beams. In such an embodiment, each beam combiner 340 of a non-first sub-component 120 combines the manipulated laser beam 192 generated by that sub-component 120 with a manipulated laser beam or composite laser beam received sequentially from the preceding sub-component 120. Furthermore, one or more sub-components 120 of component 300 may omit the optical element 142 and serve only as beam combiners, or, in the case of the first sub-component 120 (1), as guides the laser beam 190 (1) to a second sub-component 120 in the sequence for combination with another laser beam.

[0042] In one scenario, each laser beam 190 processed by component 300 is a collimated laser beam at the input of a corresponding sub-component 120, and manipulations performed by sub-components 120 (1-3) can at least partially alter the size of these collimated laser beams. For example, manipulations performed by sub-components 120 (1-3) can set the beam diameter of all collimated laser beams to the same value. In this scenario, each sub-component 120 may include a telescope. In some embodiments, component 300 matches the size of one or more collimated laser beams 190 to the size of one or more other collimated laser beams 190. For example, in an embodiment having three sub-components 120 processing three corresponding collimated laser beams 190, sub-component 120 (1) may omit optics 142, while optics 142 of sub-components 120 (2) and 120 (3) produce manipulated laser beams 192 having the same size as laser beam 190 (1).

[0043] Although component 300 can be configured to operate with at least some laser beams 190 not parallel, Figure 3 The parallel construction depicted in the image suggests a more compact and easier-to-build and manipulate design. Figure 3In the illustrated embodiment, source regions 112 are distributed along a lateral dimension parallel to the y-axis of coordinate system 302, and each optical processing region 114 is offset from the corresponding source region 112 along a longitudinal dimension parallel to the x-axis of coordinate system 302. In this embodiment, the propagation paths of the manipulated laser beam and the combined laser beam between sub-assemblies 120 and from the last sub-assembly 120 can conveniently be substantially along the lateral dimension. Furthermore, the propagation path of the laser beam 190 between the source regions 112 and the corresponding optical processing regions 114 can be substantially along the longitudinal dimension, such that the beam combiner 140 of each non-first sub-assembly 120 combines two laser beams incident on the beam combiner from mutually orthogonal directions. To increase temperature robustness, the two screw holes of the substrate 110 can be collinear with the anchor point 116.

[0044] Figure 4 This is a top view of an optical plate 400 configured to house a series of optical elements and decouple these optical elements from the thermal expansion of a substrate supporting the optical plate. The optical plate 400 is an embodiment of the optical plate 130 and can be implemented in assemblies 100 and 300 on substrates 110 and 310, respectively. The optical plate 400 includes portions 432 and 434 and two flexures 436. Each flexure 436 is connected between portions 432 and 434. Portion 432 is configured to house optical elements 140 and 142. Portion 432 defines a through-hole 466 configured to receive fasteners for securing portion 432 to the substrate, and portion 434 defines a through-hole 468 configured to receive fasteners for securing portion 434 to the substrate. In operation, the distance 460D between through-holes 466 and 468 changes as the substrate expands. The flexure 436 absorbs this change, so that the length 432L of the portion 432 remains unaffected by the thermal expansion of the substrate.

[0045] The optical plate 400 can be integrally formed, for example, machined from a single piece of solid metal such as titanium or a titanium alloy. One or more of portions 432, 434, and the flexural member 436 can have the same characteristics as... Figure 4 The different shapes depicted do not deviate from their scope.

[0046] In one application scenario, the flow cytometer includes component 300 to generate a composite laser beam 394 for interrogating a sample. In this scenario, the flow cytometer also includes a focusing lens that focuses the composite laser beam 394(3) after emission from the beam combiner 340C of the laser sub-component 120(3). This focusing lens may be mounted on substrate 310 or external to component 300. In a preferred embodiment, the optical axis of the focusing lens is aligned with the propagation axis of the composite laser beam 294(3).

[0047] Figure 5 and Figure 6 This is a top view of another optical plate 500, which includes two flexures for decoupling a series of optical elements from the thermal expansion of a supporting substrate. Figure 5 and Figure 6 Optical plate 500 is shown at two different temperatures; the structural changes are exaggerated for clarity. Figure 6 The relevant temperature is higher than that of Figure 5 The relevant temperature. Optical plate 500 is an embodiment of optical plate 400 defining slit 570. Slit 570 defines (a) portion 532, which defines a through hole 466 and is configured to receive optical elements 140 and 142, and (b) portion 534, which defines a through hole 468, and (c) two flexures 536(1) and 536(2), each flexure being connected between portions 532 and 534.

[0048] More specifically, the slit 570 partially surrounds the through-hole 468, with an edge-shaped section of portion 534 located between the slit 570 and the through-hole 468. The slit 570 extends away from the through-hole 468 in two opposite directions to two corresponding ends 572(1) and 572(2). The slit 570 thus separates portions 532 and 534 from each other. Each flexure 536 extends from portion 534 to portion 532 at a corresponding end of the two ends 572. The slit 570 can be formed by line etching.

[0049] During operation, as the substrate expands, the distance 460 between vias 466 and 468 changes from... Figure 5 The distance in the middle 460L is changed to Figure 6 The distance in the middle is 460L'. The flexural element 536 absorbs this change, such as... Figure 6 As shown, this ensures that the length 532L of portion 532 remains unaffected by the thermal expansion of the substrate (although the length 532L can be extended from the optical plate 500 itself due to thermal expansion). Figure 5 The length of 532L in the middle increased to Figure 6 The length of the flexure 532 is 532L'. Each flexure 536 may flex primarily at its corresponding end 572 and / or at its junction with the portion 536 near the edge around the through hole 468. Alternatively, a large portion of the flexure may be distributed along the length of each flexure 536 between portions 532 and 534.

[0050] In one embodiment, the width 532W of the optical plate 500 is in the range of 5 mm to 100 mm, and the dynamic range of the flexure 536 can accommodate a change of at least a few micrometers, such as at least 5 micrometers, in the distance 460L.

[0051] Figure 7The configuration 700 is shown in a side view, in which optical element 740 is directly coupled to the top surface 750 of portion 132 of optical plate 130. According to configuration 700, either optical element 140 or 142 may be directly coupled to portion 132.

[0052] Figure 8 The configuration 800 is shown in a side view, in which the optical element 740 is indirectly coupled to the top surface 750 of portion 132 of the optical plate 130 only via a mount 860. In configuration 800, the optical element 740 is directly coupled to surface 852 of the mount 860, and the mount 860 is directly coupled to the top surface 750 of portion 132. The mount 860 may be made of the same or similar material as the optical element 740. For example, both the optical element 740 and the mount 860 may be made of low CTE glass, such as borosilicate glass. Alternatively, the mount 860 may be made of the same or similar material as portion 132. The mount 860 may even be an integral feature of portion 132. According to configuration 800, either optical element 140 or 142 may be coupled to portion 132.

[0053] Figure 9 The configuration 900 is shown in a side view, in which the optical element 740 is indirectly coupled to the top surface 750 of the portion 132 of the optical plate 130 only via two posts 960 that hold the optical element 740 above the top surface 750. In configuration 900, the optical element 740 is sandwiched between the posts 960, wherein the optical element 740 is directly coupled to the side surface 952 of each post 960. Each post 960 is directly coupled to the top surface 750. Either of the optical elements 140 and 142 may be coupled to the portion 132 according to configuration 900.

[0054] Each direct bond in constructions 700, 800, and 900 may include an adhesive or be adhesive-free (e.g., formed by contact bonding). Optical elements 140 and 142 may be configured according to... Figure 7-9 The different and more complex bonding structures shown are used to indirectly bond with the top surface 750 of part 132, provided that the bonding is rigid.

[0055] The present invention has been described above through preferred embodiments and other embodiments. However, the present invention is not limited to the embodiments described and depicted herein. Rather, the present invention is limited only by the appended claims.

Claims

1. An optomechanical assembly for temperature-robust laser beam processing, comprising: A substrate, the substrate comprising: Source region, the source region being used to house the source of the laser beam, and A light processing region, the light processing region being positioned away from the source region and including a first anchor point and a second anchor point; An optical plate, disposed in the light processing area, includes a first portion and a second portion, and a flexible connector interconnecting the first and second portions. The first and second portions are respectively fixed to the substrate at a first anchor point and a second anchor point. The flexible connector allows for thermally induced changes in the distance between the first and second anchor points in the event of different thermal expansion between the optical plate and the substrate. A linearly arranged series of optical elements for manipulating a laser beam from a laser source, each of the optical elements being rigidly coupled to the first portion of the optical plate and arranged along the propagation axis of the laser beam, the propagation axis coinciding with the line between the first anchor point and the second anchor point; The coefficient of thermal expansion (CTE) of the optical plate is (a) matched to the CTE of the optical element within 20%, and (b) is lower than the CTE of the substrate.

2. The component according to claim 1, wherein, At least one of the optical elements is rigidly coupled to the optical plate via one or more rigid mounts, the rigid mounts having a CTE matching the corresponding optical element to within 20%.

3. The component according to claim 1, wherein, Each of the substrate and the optical plate is made of metal, and the optical element is made of glass.

4. The component according to claim 3, wherein, Each optical element is rigidly attached to the optical plate, either directly or via two glass pillars.

5. The component according to claim 4, wherein, The one or more glass pillars and the optical element are made of the same material.

6. The component according to claim 3, wherein, The optical plate and the optical element have a density of less than 10. -5 K -1 CTE.

7. The component according to claim 3, wherein, The optical plate is made of titanium or a titanium alloy, and the substrate is made of aluminum or an aluminum alloy.

8. The component according to claim 3, wherein, The optical plate is made of titanium or titanium alloy, and the optical element is made of borosilicate glass.

9. The component according to claim 3, wherein, The optical plate is made of α-β titanium alloy, and the optical element is made of borosilicate glass.

10. The component of claim 1, wherein, The flexible connector includes a pair of flexures, each flexure interconnecting the first portion and the second portion.

11. The component of claim 1, wherein, The optical plate defines: The first through hole located at the first anchor point; The second through hole is located at the second anchor point; as well as A slit (a) partially surrounds the second through-hole, wherein a segment of the second portion is located between the slit and the second through-hole, and (b) extends away from the second through-hole in two opposite directions to two respective ends, such that the slit separates the first portion and the second portion from each other and defines two flexures forming the flexible connector, each flexure extending from the second portion to the first portion at a respective end of the two ends.

12. The component according to claim 1, wherein, The optical elements include a telescope.

13. Temperature-robust optomechanical components for laser beam assemblies, including: The component of claim 1, wherein the substrate forms several instances of the source regions, and the component includes the optical plate and several corresponding instances of the series of optical elements coupled thereto, the several instances of the series of optical elements being configured to manipulate several corresponding instances of laser beams received from respective source regions; as well as A mirror is rigidly coupled to a first instance of the optical plate, and for one or more subsequent instances of the optical plate, one or more corresponding beam combiners are rigidly coupled to one or more subsequent instances of the optical plate to combine the laser beams in an operational sequence.

14. Temperature-robust optomechanical components for laser beam combining, including: A substrate having orthogonal longitudinal and transverse dimensions, and including a series of source regions distributed along the transverse dimension, each source region being configured to accommodate a laser source for generating a corresponding laser beam; A corresponding sequence of optical sub-assemblies, the optical sub-assemblies being offset from the source region sequence in the longitudinal dimension, each optical sub-assembly including an optical plate fixed to the substrate, each optical plate including at least one flexure to accommodate different thermal expansions of the optical plate and the substrate, at least one of the optical sub-assemblies including a linearly arranged series of optical elements, the series of optical elements (a) being rigidly coupled to the optical plate, (b) characterized in that the coefficient of thermal expansion (CTE) is matched to the CTE of the optical plate within 20%, and (c) configured to manipulate a laser beam received from the corresponding source region; as well as A mirror, rigidly coupled to the optical plate of a first optical sub-assembly in the optical sub-assembly, and a corresponding beam combiner, rigidly coupled to the optical plate of one or more subsequent optical sub-assemblies for each of the subsequent optical sub-assemblies, the mirror and the one or more beam combiners being cooperatively configured to continuously combine the laser beam.

15. The component of claim 14, wherein, The mirror and the one or more beam combiners are aligned with the general lateral propagation path of the laser beam.

16. The component of claim 15, wherein, Each laser beam has a longitudinal propagation path from the corresponding source region to a series of optical elements of the corresponding optical subassembly.

17. The component of claim 14, wherein, The substrate includes at least two source regions, and the optical sub-assembly sequence includes at least two optical sub-assemblies having a series of optical elements arranged in a corresponding linear configuration for manipulating the respective laser beams.

18. The component of claim 14, wherein, The substrate forms at least three source regions and the optical sub-assembly sequence includes at least three optical sub-assemblies.

19. The component of claim 14, wherein, For each optical sub-assembly, (a) the optical plate includes a first portion and a second portion connected to each other via the at least one flexure, each of the first portion and the second portion being fixed to the substrate at a corresponding single anchor point, and (b) the optical element being rigidly coupled to the first portion.

20. The component of claim 19, wherein, The mirror and the one or more beam combiners are coupled to a corresponding optical plate at the anchor point of the first portion to minimize displacement caused by thermal expansion of the mirror and the one or more beam combiners in the longitudinal dimension.

21. The component of claim 14, wherein, The optical plate has a lower CTE than the substrate.

22. The component of claim 14, wherein, Each series of optical elements includes multiple lenses for changing at least one of the size and divergence of the laser beam.

23. The component of claim 22, wherein, Each of the lenses is rigidly coupled to the optical plate directly or via one or more rigid mounts, each rigid mount having a CTE matching the optical element to within 20%.

24. The component of claim 14, wherein, The laser beam provided by the beam combiner of the last optical subassembly in the optical subassembly is collimated.

25. The component of claim 24, further comprising a laser source associated with each source region, wherein each laser source is configured to transmit a corresponding laser beam as a collimated input laser beam to a corresponding optical sub-component, and wherein at least a series of optical elements includes a telescope for changing the diameter of the laser beam while maintaining collimation.

26. Flow cytometer, including: The component of claim 14 further includes the laser source associated with each source region for generating a composite laser beam consisting of continuously combined laser beams; as well as A focusing element for focusing the composite laser beam onto the sample flow path.

27. An optomechanical assembly for temperature-robust laser beam processing, comprising: A substrate, the substrate comprising: Source region, the source region being used to house the source of the laser beam, and A light processing region, the light processing region being positioned away from the source region and including a first anchor point and a second anchor point; An optical plate, disposed in the light processing area and comprising a first portion and a second portion, and a flexible connector between the first and second portions, wherein the first and second portions are respectively fixed to the substrate at a first anchor point and a second anchor point, wherein the flexible connector allows for thermally induced changes in the distance between the first and second anchor points in the event of different thermal expansion between the optical plate and the substrate; and A linearly arranged series of optical elements for manipulating a laser beam from a laser source, each of the optical elements being rigidly coupled to the first portion of the optical plate; The coefficient of thermal expansion (CTE) of the optical plate is matched to the CTE of the optical element within 20%.

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