A laser beam module package comprising stamped metal free form reflective optical device

Abstract

An LBM package and a method for packaging an LBM using an array of stamped metal mirrors that fold a light beam, correct the shape of the light beam, fold and / or redirect the propagation of the light beam. An array of mirrors may be integrated or assembled within the LBM to provide beam shaping and redirection of the high power beam near the laser diode. The LBM includes a stamped metal free form mirror or reflector having an off-axis parabolic shape configured to fold and collimate the laser beam. Precision stamping processes are deployed to produce micro free form mirror arrays in mass applications. The mirror array simplifies the optical path and eliminates passive components such as refractive lenses and dichroic filters combining RGB beams. Stamped metal optical components with micro-scale free form mirrors in the LBM are resistant to high temperatures and can thermally diffuse heat away from the reflective surface for high power applications.

Description

Technical Field

[0001] 1. Priority claim

[0002] This application claims priority to (a) U.S. Provisional Patent Application No. 63 / 331,712, filed April 15, 2022; (b) U.S. Provisional Patent Application No. 63 / 481,141, filed January 23, 2023; and (c) U.S. Provisional Patent Application No. 63 / 481,146, filed January 23, 2023. These applications are fully incorporated herein by reference as if fully set forth herein. All publications mentioned below are fully incorporated herein by reference as if fully set forth herein. Background Art

[0003] The present invention relates to laser modules, and more particularly to laser module packages that include reflectors to enable laser beam reshaping and redirection.

[0004] Description of Related Technology

[0005] Figure 1A The laser beam output of a typical edge-emitting diode laser 2 is depicted. In particular, due to the different divergence angles in the orthogonal (xy) directions, the laser beam propagates to a beam spot with an elliptical cross-section rather than a circular cross-section. For example, Figure 1B As shown, the laser beam 6 emitted from the edge emitting diode laser 2 exhibits a slow axis divergence angle θ s and the fast axis divergence angle θ f , which are typically about 10 degrees and 25 degrees, respectively. In addition, the beam has astigmatism, where the slow axis focus is behind the fast axis focus and separated by an astigmatism distance. For some applications, it is desirable to shape the laser beam 6 to obtain a nearly perfectly collimated beam with a nearly circular (or square) cross-section (low divergence angle and nearly equal in both the fast and slow axes), and it may be further advantageous for some applications if the beam has uniform irradiance at the intended target location of the laser beam incidence.

[0006] The diode laser is packaged in a laser beam module (LBM). The LBM is equipped with a refractive lens inside or outside the LBM to shape and improve the quality of the folded laser beam. In addition, for an LBM with an edge-emitting diode laser mounted horizontally relative to the output path of the LBM, a glass prism with a flat reflective surface is assembled into the LBM to fold the source laser beam 90 degrees before shaping it with a refractive lens. Figure 2As shown, the prior art LBM 10 includes a housing frame 1, wherein an edge emitting laser 2 is mounted on a base 11, which is attached to a substrate 3, which also supports a glass prism 4 having a planar reflective surface 5. A divergent laser beam 6 propagates to the reflective surface 5, which is redirected by the reflective surface 5 to pass through a glass cover 7 of the housing 1. A plano-convex lens 8 is disposed above the glass cover 7 to reduce the divergence angle of the beam 6 into a more collimated beam 9 as the output of the LBM package 10. Therefore, current LBM packages involve a complex assembly of separate components including prisms and lenses and several bonded joints, requiring rigorous alignment and assembly processes. Therefore, additional considerations and challenges are required to meet the performance, tolerance, reliability and overall quality requirements of specific applications.

[0007] Augmented, virtual, and mixed reality (individually and collectively “XR”) displays require miniature light engines that can be worn near the eye. Typically, XR displays based on a laser beam scanner (LBS) architecture use light from a hermetically sealed LBM and scan the light into a combiner using a microelectromechanical system (MEMS) mirror. To date, LBMs for XR applications are hermetically sealed packages that encapsulate the red (λ r =640nm), green (λ g =520nm) and blue (λ b =450nm) laser diodes (LDs). LDs are usually edge-emitting and have a wavelength of approximately θ f = 22° and θ s =8° for the fast and slow axes. Therefore, it is necessary to shape the beams so that all three beams are nearly collimated and combined into a coincident circular spot on the scanning MEMS mirror. The light reflected from the (one or more) scanning mirrors is passed through a combiner to generate the display image. All three laser beams must be corrected to achieve a circular spot on the scanning mirror. To date, this has been achieved by optical components of the individual lasers sealed in corresponding hermetic packages, dichroic beam splitters, and refractive lenses for slow and fast axis correction lenses. Therefore, for a light engine based on an LBS architecture, the RGB LBM (each with Figure 2 The general structure of the LBM package 10 depicted in FIG. 1 utilizes a glass prism inside a separate laser module package (each with a different color) to fold the laser beam 90 degrees, and then three separate plano-convex lenses outside the three laser module packages are used to collimate the beam. All six components are individually aligned and secured with glue, which requires a rigorous alignment and assembly process.

[0008] Miniature light engines for XR are becoming more common and production volumes are rising. This requires new solutions for producing optics suitable for these applications with reduced weight and size on the light engine package.

[0009] Additionally, advances in high-power solid-state and fiber lasers continue to enable key technologies for society as the number of applications such as manufacturing processes, LiDAR, telecom / datacom, aerospace, and defense continues to increase. The power level depends on the specific requirements of the application, but can range from a fraction of a watt to over 10kW. High-power lasers have many applications in diverse fields such as optical communications, material processing (manufacturing), free-space optics, and 3D vision technologies such as LiDAR. These applications require optical components that change or redirect laser beams to withstand harsh environments, be stable to thermal variations, and tolerate high power levels that could otherwise damage materials or surfaces. Additionally, incoherent combinations of multiple laser beams, such as those used in directed energy weapons, can achieve even greater power levels.

[0010] However, since the beginning of laser technology, limitations in the power handling capabilities of optical components have been an obstacle to the development of laser systems and applications operating at high power levels and with improved beam quality. High-power lasers introduce substantial heat loads that cause thermal aberrations. For example, early thermal analysis found that even refractive optics made of fused silica and BK7 subjected to 1.5 kW of laser power could result in a temperature rise of about 2.5 K due to energy absorption. High-power lasers can damage optical components by melting, ablation, cracking, etc. Some of the laser damage mechanisms are thermal degradation effects, defect-induced damage, and nonlinear effects leading to catastrophic failure of optical media. Laser-induced damage (LID) is most often limited by defects at the surface or within thin-film coatings. Therefore, the limiting value of an optical component is often given by the damage threshold of its surface, which may be coated to affect the optical properties.

[0011] The surface quality of reflectors or mirrors is critical to prevent component failure under high power operation. Due to the high intensity incident on optical components in LBM for high power applications, optical components usually require lenses and mirrors manufactured by expensive processes. In order to achieve the shape and surface quality requirements, expensive processes such as single-point machining or grinding followed by polishing have been used to date to achieve the shape and finish requirements in refractive or reflective materials. This is challenging for high-volume commercial products, especially when the application also has strict cost targets.

[0012] High-power laser systems for material processing, 3D imaging (such as LiDAR), and optical communications are becoming more common and production volumes are rising. This requires new solutions for producing reflective optics for these applications.

[0013] Therefore, there is a need for an improved method of packaging LBMs that can reduce costs for high-volume applications and further improve tolerances, manufacturability, and reliability. Summary of the invention

[0014] The present invention overcomes the shortcomings of the prior art and provides a new solution for producing LBMs with reflective optics suitable for high power and miniaturized applications. The present invention provides design flexibility for building LBMs while improving size, weight, reliability and cost.

[0015] In one aspect, the present invention provides an improved LBM package (e.g., a red, green, and blue (RGB) LBM) and method for packaging an LBM that uses a stamped metal mirror array that folds the beam, corrects the beam shape, and redirects the beam propagation (e.g., to a MEMS mirror). The mirror array can be assembled within a laser diode package to provide beam shaping and redirect high-power beams near the laser diode.

[0016] In one embodiment, the LBM of the present invention comprises a stamped metal free-form mirror or reflector (e.g., a stamped aluminum mirror) having an off-axis parabolic shape that is configured to fold and collimate a laser beam (e.g., a high-power laser similar to those used in LiDAR systems). The metal mirror tolerates high powers due to its high damage threshold and thermoelastic properties. The metal mirror performs much better than similar mirrors made of polymers or glass because it does not have the catastrophic transient temperature rise caused by high-power pulsed lasers and has less thermal aberration due to steady-state temperature rise. The stamped free-form mirror can reduce costs for high-volume applications.

[0017] In one embodiment, an ultra-high precision stamping process is deployed to manufacture arrays of micro-freeform mirrors for high-volume applications. The mirror array simplifies the optical path and eliminates passive components, such as refractive lenses for slow-axis and fast-axis correction, and dichroic filters for combining RGB beams. This new approach reduces the size, weight, and cost of LBMs for XR applications as well as for high-power applications. Stamped metal optical components with micro-scale freeform mirrors in LBMs withstand high temperatures and can dissipate heat from the reflective surface for high-power applications.

[0018] In one embodiment employing a free-form reflective surface, a specific mirror array with an aspherical shape is configured to fold and collimate the beams from three RGB laser diodes within the laser module package. Stamped metal mirrors shape the laser diode beams for better roundness and beam combining.

[0019] The present invention relates to a laser beam module package as defined in the claims, comprising: a laser array that outputs an incident laser beam having an elliptical cross-sectional beam profile due to astigmatism of the incident laser beam; a housing having a substrate that supports a frame having a top side, wherein the housing has a space defined by the frame, the space receiving the laser array and supporting the laser array on the substrate within the space; an optically transparent cover that is hermetically sealed to the top side of the frame; and a reflector array that includes a reflector body of a metallic material having a plurality of reflectors defined on a surface of the reflector body by metal stamping the surface of the reflector body to form an array of smooth free-form reflective surfaces of the reflector array, wherein the reflector body is supported by the housing and housed within the space of the housing, wherein the reflector array is optically aligned with the laser array, wherein the free-form reflective surface is configured to reflect and shape the beam profile of a corresponding incident laser beam to produce a corresponding output laser beam that is directed toward the cover for output from the laser beam module package.

[0020] In one embodiment, the free-form reflective surface is configured to correct astigmatism of a laser beam to produce an output laser beam that is more closely aligned with a collimated beam.

[0021] In one embodiment, the mirror body comprises a monolithic block of metallic material, wherein the mirror is defined by stamping a surface of the monolithic block to integrally and simultaneously form a plurality of mirrors, and wherein the mirror is defined on a surface of the mirror body facing a corresponding laser in the laser array. The mirror body is supported by a substrate and / or a frame.

[0022] In one embodiment, the monolithic block is a base that is structurally coupled to the frame, wherein the base is inserted through an opening in the frame, wherein the base is structurally coupled to the frame when stamped to define a reflector on the body. In one embodiment, the base surrounds an inner wall of the opening in the frame, thereby defining an opening in the reflector body to receive the laser array.

[0023] In another embodiment, the reflector body comprises a reflector array block having a bottom surface for attachment to a substrate and an angled surface facing a laser array, wherein the reflector array block comprises a monolithic block, and wherein the reflectors are defined by stamping the angled surface of the monolithic block to integrally and simultaneously form a plurality of reflectors before attaching the bottom surface of the reflector array block to the substrate. In another embodiment, the reflector array block further comprises an outer frame covering a surface of the monolithic block other than the angled surface, wherein the frame defines the bottom surface of the reflector array block for attachment to the substrate.

[0024] In one embodiment, the reflector is a concave aspherical reflective surface of the reflector body.

[0025] In one embodiment, the housing is made of a first material and the mirror body is made of a second material; wherein the second material is different from the first material. In a further embodiment, the substrate and frame are separate components made of different materials, and wherein the frame is hermetically sealed to the substrate.

[0026] In one embodiment, the mirror array includes a first mirror array and a second mirror array, the first mirror array includes a first group of free-form mirrors, the second mirror array includes a second group of free-form mirrors corresponding to and facing the first group of mirrors, wherein an incident laser beam is directed to the first group of mirrors, wherein the first group of mirrors collimates and reflects the incident laser beam to the second group of mirrors, wherein the second group of mirrors further collimates and directs the collimated output laser beam to the cover for output from the laser beam module package. In another embodiment, the first group of mirrors are free-form aspheric cylindrical mirrors, and the second group of mirrors are free-form aspheric cylindrical mirrors.

[0027] In one embodiment, the free-form reflective surface of the mirror array is configured to converge the output laser beam into a spot at a target plane at a reference distance from the laser beam module package.

[0028] In another aspect, the invention relates to a method or process of assembling a laser beam module package to obtain the above structure, including stamping to form a free-form reflective surface in a mirror array. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] For a more complete understanding of the nature and advantages of the present invention and the preferred mode of use, reference should be made to the following detailed description read in conjunction with the accompanying drawings.In the following drawings, the same reference numerals and / or numbers represent the same or similar parts throughout the drawings.

[0030] Figure 1A and 1B A typical laser beam emitted from an edge-emitting laser diode is shown.

[0031] Figure 2 is a schematic configuration of a prior art LBM package.

[0032] Figure 3 is a schematic configuration of an LBM package with an aspheric stamped metal reflective surface according to one embodiment of the present invention.

[0033] Figures 4A to 4E FIG. 1 shows an LBM package according to an embodiment of the present invention, wherein Figure 4A It is an exploded view. Figure 4BIt is a perspective view. Figure 4C is a cross-sectional perspective view (without cover), Figure 4D is a top view, and Figure 4E It is a cross-sectional view.

[0034] Figure 5A An array of aspherical reflective surfaces is schematically depicted; Figure 5B Schematic depiction of the optical simulation for steering and shaping an incident laser beam; Figure 5C Schematic depiction of the optical simulation of steering and shaping an incident laser beam at a target plane using a stamped mirror array; Figure 5D Schematic depiction of the optical simulation of steering and shaping an incident laser beam through an optical aperture; Figure 5E Schematically shows Figure 5D Beam profile of a collimated beam in the optical simulation.

[0035] Fig. 6A Schematically depicts an optical simulation of combining RGB beams from a mirror array, where the RGB beams overlap at a target plane at a reference distance; Figure 6B Schematically shown are the RGB beam paths from the RGB lasers to the target plane at a reference distance.

[0036] Fig. 7A schematically illustrates a comparison of beam profiles of a laser beam reflected from an aspherical reflective surface and a faceted reflective surface; Figure 7B Schematically illustrated are beam paths of laser beams reflected from corresponding free-form mirrors having faceted reflective surfaces to achieve a target beam profile for the combined beam at a target distance from the reflective surface.

[0037] Figures 8A to 8D shows an LBM package according to another embodiment of the present invention, wherein Fig. 8A It is a perspective view. Figure 8B yes Fig. 8A A perspective view of the mirror array block in Figure 8C It is a cross-sectional perspective view. Fig.8D is a schematic diagram showing heat transfer from a mirror array block to a substrate and the environment; Fig. 8E is an alternative mirror array block according to another embodiment of the present invention.

[0038] Fig.9A is a schematic perspective layout of two complementary mirror arrays for steering and shaping multiple laser beams according to one embodiment of the present invention; Fig. 9B Schematically depicts the optical simulation of the beam profile at the target plane at a reference distance; Fig. 9C Schematically depicted the optical simulation of the residual wavefront of a collimated beam at the target plane at a reference distance.

[0039] Fig. 10A is a schematic perspective layout of two complementary mirror arrays for steering, shaping and redirecting / combining multiple laser beams at a target plane at a reference distance according to one embodiment of the present invention; Fig. 10B The beam overlap of the laser beams at the target plane at a reference distance is schematically depicted. DETAILED DESCRIPTION

[0040] The present invention is described below with reference to various embodiments with reference to the accompanying drawings. Although the present invention has been described according to the best mode for carrying out the purposes of the present invention, those skilled in the art will appreciate that variations can be implemented in light of these teachings without departing from the spirit or scope of the present invention.

[0041] The present invention is described below using an aspherical reflective surface as an example of a free-form reflective surface. This does not exclude the use of other types of free-form reflective surfaces according to the present invention.

[0042] In the illustrated embodiment, the present invention provides an improved method for packaging red, green and blue (RGB) LBMs using stamped mirror arrays that fold the beam, correct the beam shape and redirect the beam propagation (e.g., to MEMS mirrors). The mirror array simplifies the optical path and eliminates passive components such as dichroic filters and refractive / diffractive lenses, such as those used for slow-axis and fast-axis correction. This new approach reduces the size, weight and cost of LBMs, for example, for XR applications.

[0043] Figures 4A to 4E FIG. 4 shows an LBM package P according to an embodiment of the present invention, which can be made of Figure 3 Schematically indicated. Figure 3 As shown, the LBM package P includes a sealed housing including a frame F supported on a substrate S and a cover C supported on the frame F. The LBM package P also includes a laser array L (e.g., edge-emitting diode lasers corresponding to R, G, and B lamps) supported on a riser R on the substrate S. The array of lasers L may be included in a diode laser chip. An array of non-planar structured reflective surfaces or reflectors M is integrally and simultaneously defined by a base B of stamped metal material, which is optically aligned with the array of lasers L. In the illustrated embodiment, the base B is made of a monolithic block of metal (e.g., Al), wherein the reflectors M are integrally and simultaneously defined on the base B by a metal stamping process. The base B may be supported by the frame F and / or the substrate S, as shown in FIG. Figure 4C and 4E As shown, the laser array L / diode laser chip is located in the opening in the base B. An optically transparent plate is used as a cover C (eg, a glass cover). The LBM package P is hermetically sealed between the frame, the cover C, and the substrate S.

[0044] Each non-planar mirror M in the array is used to reflect and shape (e.g., collimate or focus) a divergent incident light beam without relying on any refractive and / or diffractive optical elements (i.e., no lens is required for shaping the incident light beam). Each reflector M is an exposed free surface of the base B (i.e., a surface exposed to the air or not inside the body of the base B), which has an exposed reflective free side facing the incident laser L, and wherein the exposed reflective free side includes a structured reflective surface profile, where light is guided to and from the corresponding laser L. Each reflector M bends, reflects and / or shapes the incident light beam from the laser L. Depending on the geometry and shape (e.g., curvature) of the structured reflective surface profile, the reflector M can collimate, expand or focus the incident light beam. For example, the structured reflective surface profile can include one of the following geometries / profiles: (a) elliptical, (b) off-axis parabolic, or (c) other free-form reflective optical surfaces. For example, to provide optical power, the mirror surface can have a surface parameter function of any of the following alone or in a superposition: an ellipsoidal or hyperbolic conical focus, an annular aspheric surface with various numbers of even or odd aspheric terms, an XY aspheric surface with various numbers of even or odd terms, Zernike polynomials of various orders, and various simpler surface families contained by these functions. The surface can also be a free-form surface that does not have symmetry along any plane or vector. For example, in the illustrated embodiment, the micro-reflector is typically free-form and concave.

[0045] The substrate S may be made of AlN (aluminum nitride) and its top surface is patterned with AuSn (gold / tin) plating for soldering to the bottom of the frame F. The cover C may be made of glass or quartz and its bottom surface is patterned with AuSn plating for soldering to the top of the frame F. The frame F may be made of Kovar with AuSn plated on the top and bottom surfaces facing the bottom surface of the cover C and the top surface of the substrate S, respectively. The AuSn plating facilitates soldering of the cover C and the substrate S to the frame.

[0046] In the embodiment shown in Figure 4, the sealed LBM package P includes a stamped metal base B with three mirrors that simultaneously fold, redirect and shape each laser beam. In one embodiment, the base B is made of aluminum (Al), and the mirrors M are defined by the integrally stamped aluminum base B.

[0047] According to the present invention, the reflectors M are manufactured using an ultra-high precision stamping process that produces a free-form miniature or microscale reflector surface. During the stamping process, the punch and die squeeze the metal workpiece until the metal yields and undergoes plastic deformation, thereby imposing the shape of the punch and die into the workpiece. The stamped surface of each reflector is smooth, with a finish similar to a polished finish. (In alternative embodiments, the structured reflective surface may have defined corresponding to different equivalent reflective surfaces (e.g., combined Fig. 7A and 7B These aluminum mirrors M have a form error of better than 1 μm and a low R a 4nm surface roughness, folding and shaping (focusing, collimating or expanding) the light beam. In one embodiment, the stamped mirror M is made of high purity aluminum (4N aluminum with a purity of 99.99%). Aluminum has a low yield strength and is very ductile, which makes it suitable for stamping at room temperature. In addition, aluminum has high reflectivity throughout the optical spectrum 12, 90% to 92% in the UV range, dropping to about 86% around 0.8 microns, then rapidly increasing to about 94% at 1μm, and continuing to increase to about 98% around 10μm. For visible light applications, the reflectivity can be improved by depositing a gold film or a custom coating.

[0048] Dimensional tolerances sufficient for optical components with sub-micron tolerances in the size, form, and position of features can be achieved. This ultra-high precision stamping technology is used to manufacture metal optical benches (MOBs) for optical communications and metal optical reflectors (MORs) for LED lighting. The manufacturing technology can also be used to design and manufacture arrays of metal free-form mirrors, which can shape and redirect laser beams in laser beam modules. Micromirrors extend the utility of MOBs by enabling the beam to be folded or even shaped using aspheric mirrors that focus or expand the beam. This is achieved without any additional cost of refractive or diffractive lenses, and the mirrors are aligned to the bench features through the stamping process.

[0049] U.S. Patent No. 7,343,770 (which has been acquired by Senko Advanced Components, Inc., a common assignee of the present invention) discloses a novel precision stamping system for manufacturing close tolerance parts. This inventive stamping system can be implemented to produce the structures of the LBMs disclosed herein (including structures for the base B having the reflector M discussed above and similar stamped structures in the alternative embodiments discussed below). These stamping processes involve stamping a ductile bulk metal material (e.g., a metal blank or billet) to form final surface features of close (i.e., small) tolerances, including a reflective surface having a desired geometry that is precisely aligned with other defined surface features. U.S. Patent No. 9,782,814 (which has been acquired by Senko Advanced Components, Inc., a common assignee of the present invention) further discloses a composite structure comprising a main portion and an auxiliary portion (insert) of different metal materials. The auxiliary portion is formed by stamping. When the auxiliary portion is stamped, it interlocks with the main portion and simultaneously forms the desired structured features, such as a structured reflective surface, on the auxiliary portion. Using this approach, relatively more critical structural features on the auxiliary portion are more accurately formed with further consideration of defining dimensions, geometry, position relative to the main portion, and / or finish with relatively tight tolerances. The disclosed composite structure can be employed to produce a reflector M within a frame F disclosed herein.

[0050] refer to Figure 4E, and the stamping process discussed in U.S. Patent No. 9,782,814 (incorporated herein by reference in its entirety), the base B is in the form of an Al insert that is placed into a through opening in a frame F having an annular chamfered top edge CT and a bottom edge CB. The insert is then formed by stamping, including using a stamping punch that simultaneously defines all of the mirrors M in the array. When the insert is stamped, it interlocks with the chamfered edges CT and CB of the frame F, forming a rivet structure corresponding to the base B, thereby structurally coupling to the frame F and simultaneously forming an array of mirrors M on the base B. The base B is thereby fixedly coupled to the frame like a rivet against the annular top chamfered edge CT and the bottom chamfered edge CB. In this configuration, the base B surrounds the inner wall of the through opening in the frame, thereby defining an opening in the base to receive the array of lasers L. With this approach, the mirrors on the base B are simultaneously precisely formed relative to each other, and the size, geometry, position relative to the frame F, spatial relationship of the mirrors within the array, and / or finish are defined with relatively small tolerances. The stamping process may involve several separate stamping operations, but the final stamping operation simultaneously completes the precise definition of the size, geometry, and finish of all the mirrors M in the array and their positions relative to each other and the frame F. By precisely positioning the laser L (or laser diode chip) on the substrate S relative to the frame F and within the central opening in the base B, the relative position of the laser L and the mirror M can be precisely defined, and thus the desired optical alignment of the laser L and the mirror M (i.e., the optical axis of the components) can be precisely achieved. This simplifies the overall assembly process to improve manufacturability without compromising tolerances and reliability.

[0051] refer to Figure 4C, the micro-mirrors M may have different radii of curvature and different focal points of the XY axis (e.g., a dual-axis hyperbolic micro-mirror), which corrects the slow and fast axis variations of a specific target plane at a specific reference distance. The stamping process of the mirrors was designed using a combination of nonlinear finite element analysis and computer simulation. Based on typical results from simulations of the stamping process, the plastic strain is relatively uniform over most of the area inside the hole, which indicates a fairly uniform grain structure on the mirror surface; the plastic strain distribution between the center of the hole and the perimeter of the hole and beyond the hole can be predicted, so that the shape error across the surface of the mirror array can also be predicted from the analysis. The shape error is calculated by calculating the deviation between the predicted 3D shape of the stamped mirror array and the ideal 3D CAD model. The predicted shape error is corrected by adjusting the stamping tool. It has been found that the simulation matches the experimental observations and can be relied on as a reliable basis for compensating the stamping tool geometry. During the stamping process, the punch and die squeeze the metal workpiece until the metal yields and undergoes plastic deformation, thereby imposing the shape of the punch and die into the workpiece. Stamping tools can be produced that can form microscale features in the base B with position, size, and shape tolerances better than one micron. The mirrors can be as small as a few hundred microns in size with sub-micron precision and with surface finishes down to R a 4nm without secondary processing.

[0052] Furthermore, the free-form surfaces in the stamped aluminum reflector arrays of the present invention improve the quality of the beam beyond that which can be achieved with refractive lenses that are spherical or plano-convex lenses.In the illustrated embodiment, an off-axis parabola is used to achieve collimation of a diverging beam. Figure 5A schematically depicts an array of free-form reflective surfaces that may be similar to the mirrors M discussed above; Figure 5B Schematically depicting an optical simulation of a mirror M that deflects and shapes (collimates) an incident laser beam into a shaped beam LB; Figure 5C Schematically depicted is the optical simulation of a mirror M using a stamped mirror array (in Figure 5C , which can be defined in Figure 5C The mirror M is a mirror that is used to deflect and shape (collimate) the incident laser beam into a shaped beam LB at a target plane tp at a reference distance d, as discussed in the above embodiment shown in the figure. Each mirror M can be optimized for a specific divergence characteristic (divergence angle and amount of astigmatism) of the beam emitted from the laser diode array. Figure 5C The optical paths of three laser beams LBs shaped by the mirror array are shown in FIG. 1 using light rays simulated using commercially available software.

[0053] Due to the difference between the divergence angles of the fast and slow axes of the laser, the output beam from the stamped mirror reflector will have a beam profile that is elongated to the target plane tp (see Fig. 7A Beam profile on the left hand side). To achieve better roundness of the collimated beam, the optical aperture O can be used to tailor the spot size along the fast axis. Figure 5D An optical simulation in which a mirror M deflects and shapes an incident laser beam LB and passes the shaped beam LB through an optical aperture O is schematically shown. Figure 5D A ray tracing simulation is shown with the addition of an optical aperture O which obscures a portion of the shaped beam LB to achieve a better circularity of the collimated beam LB'. Figure 5E Schematically shows Figure 5D The beam profile of the synthetic collimated beam LB' in the optical simulation. Figure 5E As shown, the shape of the beam profile is no longer elongated and the width in both directions is approximately 0.62 mm1 / e 2 However, nearly 50% of the output power is lost due to the optical mask, which adversely affects power consumption, resulting in shorter battery life or larger batteries.

[0054] The optical path of LBM package P is Figure 3 , which has a stamped array of aspheric aluminum mirrors that simultaneously fold and collimate the beams from an array of lasers L. The entire aluminum mirror array can be packaged within a hermetic LBM package with a single attachment to a frame F (i.e., base B on which the mirrors are defined is "riveted" to frame F), thereby consolidating the functionality of separate independent prisms and refractive lenses required in prior art LBM packages (see Figure 2 ).

[0055] As an example, in Figure 4E In the embodiment shown, the height h of the frame F can be on the order of 1 mm. Micro-arrays of free-form reflectors can be produced for LBMs suitable for XR applications. For these applications, the reflectors fold, route and correct the beams using a single optical component to reduce the size and weight of the light engine. This new approach enables the size, weight, reliability and cost of LBMs to be reduced, and therefore the size, weight, reliability and cost of light engines for XR applications, by eliminating the need for collimating refractive lens assemblies; for some applications, it can also eliminate the assembly of dichroic filters that combine RGB beams. In addition, the assembly process is simplified to a single optical alignment between the mirror array and the laser diode, which reduces manufacturing costs.

[0056] In another aspect of the invention, a mirror M in an LBM package P can be configured to project a shaped laser beam LB from an array of lasers L (e.g., RGB lasers) to a spot sp on a target plane tp at a target or reference distance d from the lasers L. The geometry of the mirror M in this embodiment will be different than the corresponding mirror M in FIG5 to effectively rotate (tilt) the mirror M so that the reflected beams intersect at the target plane tp. The overlapping beams LB at the target plane can moderate the RGB components of the aiming point sp to achieve a desired color by moderating the relative intensities of the RGB laser beam outputs. Fig. 6A Schematically depicts an optical simulation of combining RGB beams from a mirror array, where the RGB beams overlap at a target plane tp at a reference distance d from the respective lasers L; Figure 6B Schematically shows the RGB beam paths from RGB lasers spaced at a pitch p to a target plane tp at a reference distance d. The beams from the blue laser and the red laser on both sides of the green laser converge to a spot sp at the target plane tp at a target angle a. The target distance d can range from a few millimeters to hundreds of millimeters.

[0057] In another embodiment, a faceted free-form mirror M' may provide an efficient way to achieve "flat-top" beam shaping. Fig. 7A A comparison of the beam profiles of a laser beam reflected from an aspherical reflective surface and a faceted reflective surface is schematically shown. Fig. 7A On the left hand side in , a light source (e.g., a green diode laser) is aimed at a target plane at a distance of 4 mm from the reflector M. Fig. 7A On the right-hand side in FIG, the same light source projects a beam at the same target plane at the same distance from reflector M' (i.e., 4 mm). Unlike reflector M, reflector M' has a 2 × 4 patch-faceted free-form reflective surface. The corresponding beam profile for reflector M' is shown as a flat "top hat" beam, where the intensity of the light is more uniform over a larger area, resulting in a less circular beam profile. Figure 7B Schematically illustrates the beam paths of laser beams (two are shown for simplicity) reflected from corresponding free-form mirrors M' having faceted reflective surfaces to achieve a target beam profile for the combined beam at a target distance from the mirror M'. Each facet is defined by a NURBS (Non-Uniform Rational B-Spline) surface patch that together form the composite surface of the mirror M'; each NURBS surface can be optimized to achieve a target beam profile at a target distance.

[0058] The present invention also provides a more reliable platform for high power LBMs. High power optical components are used in many applications with a range of power levels. For example, material processing such as laser cutting, welding, marking, drilling use lasers with powers in the 500W-750W range and are commercially available. In telecommunications, higher powers help achieve higher data rates over longer transmission distances. Pump lasers (980nm) are used in erbium-doped fiber amplifiers, which provide operating power levels of 100mW to 1.6W for telecommunications. Fiber-coupled diode lasers with powers of 10W-200W are used for laser pumping and material processing. Emerging autonomous vehicles require semiconductor lasers with hundreds of mW for light detection and ranging (LiDAR), while some other LiDAR applications (military, aerial terrain mapping, agriculture, space applications) may require even higher power levels (tens of kilowatts to tens of megawatts) using fiber lasers or solid-state lasers.

[0059] By using stamped mirrors made of high-purity aluminum (4N aluminum with a purity of 99.99%), heat transfer is significantly improved to reduce damage from high-power lasers. Even when the incident laser power is not close to the potential damage threshold, the aluminum mirror still has significant optical advantages. Aluminum is an excellent thermal conductor; it easily dissipates any absorption of optical power from the mirror surface. Heat can flow out of the mirror and into the substrate or into the surrounding environment by thermal conduction or convection. This can minimize temperature rise in steady-state and transient applications. In addition, the high thermal diffusivity of aluminum prevents severe transient temperature spikes in pulsed high-power laser applications. These benefits are particularly evident when compared to mirrors made of polymers commonly used for injection molding, such as commercially available polyetherimide (PEI). It has been found that the thermal diffusivity a of aluminum is more than several hundred times greater than that of PEI (e.g., about 800 times). The coefficient of thermal expansion (CTE) of aluminum is only about 35-40% of that of PEI. The impact of these properties is taken into account when designing mirrors for LiDAR applications using the concepts of the present invention.

[0060] According to another aspect of the present invention, a free-form mirror is developed to accommodate high power applications, such as LiDAR applications. Figures 8A to 8D FIG. 1 shows an LBM package according to another embodiment of the present invention, wherein Fig. 8A It is a perspective view. Figure 8B yes Fig. 8A A perspective view of the mirror array block in Figure 8C It is a cross-sectional perspective view. Fig.8D is a schematic diagram showing heat dissipation from a mirror array block to a substrate and the environment; Fig. 8E is an alternative mirror array block according to another embodiment of the present invention.

[0061] exist Fig. 8AIn the LBM package P' shown, a mirror array block MB defining an array of free-form mirrors M" is placed within a frame F' and attached (e.g., by welding) to a substrate S, which is hermetically sealed to the base of the frame F'. A plurality of lasers L' (e.g., configured in laser diodes) are positioned on the substrate S. In this embodiment, four lasers L are shown, corresponding to the four mirrors M" on the mirror array block MB (see also Figure 8B ). Also refer to Figure 8C , an optically transparent plate cover C (as in the previous embodiments of the LBM package P) is provided to hermetically seal the package P". Figure 8C A cross section through the laser L' and the free-form mirror M" is shown. Reference features f may be provided on the mirror array block MB to facilitate identification of the orientation of the mirror array block MB. The entire assembly is shown to be hermetically sealed between the frame F', cover C and substrate S.

[0062] The mirror array block MB is made of metal (e.g. 4N aluminum), as is the case with the base B in the previous embodiment. In the illustrated embodiment, the mirror array block MB is made of a monolithic block of metal (e.g. Al) with the mirrors M" integrally and simultaneously defined thereon by a metal stamping process. Figure 8C A similar reflector is shown that corrects and redirects the light beam emitted within a high power laser diode package. Similar reflector design considerations and stamping processes and procedures apply to this embodiment. Unlike earlier embodiments, the reflector array M" is pre-defined simultaneously on a separate aluminum block (MB) before the reflector array block is attached to the substrate S to complete the formation of the reflector array block having the reflector array M". The stamping process and procedure may be modified from the process and procedure applied to the previous embodiments. It should be noted that the stamping process used for this embodiment will define (e.g., simultaneously / integrally form) the geometry and position of the reflector M" and the geometry and relative position of the outer surface of the reflector array block MB (having an overall generally triangular cylindrical structure). Therefore, the bottom surface of the reflector array block MB is the reference surface, and the optical axis of the reflector M" is defined relative to this reference surface during the stamping process. After this bottom surface of the mirror array block MB is attached to the substrate S, the optical axis of the mirror M" is known relative to this bottom surface, thereby facilitating optical alignment of the mirror M" with the laser L' also attached to the substrate S.

[0063] This embodiment can also be suitable for XR applications. As an example, based on this embodiment, the size of the stamped mirror can be about 2.1 × 5 × 0.9 mm, and the volume is about 5.9 mm 3 ; When made of high purity aluminum with a density of 2.7 g / cm3, the mass is about 16 mg. In prior art LBMs, the volume of the prism is estimated to be about 1 mm 3, with a mass of about 2.5 mg, and the volume and mass of each lens are about 1.26 mm 3 and 3.4 mg. Therefore, compared with the aluminum reflector array block MB of the present invention, which has a total mass of about 16 mg, the total mass of a set of three prisms and three lenses in the prior art LBM package is about 17.7 mg (excluding the fixture and epoxy resin for the lens). In addition, the reduced bill of materials (BOM) and simplified packaging process further reduce the assembly complexity of the entire light engine and improve reliability due to fewer bonding joints.

[0064] Thermomechanical finite element analysis (FEA) is used to evaluate the changes in mirror shape due to changes in operating temperature and incident flux. The optical performance is compared to polymer mirrors under steady-state conditions (such as a continuous wave laser beam) and transient conditions (such as pulsed lasers used in LiDAR applications). Thermomechanical shape changes are subsequently used in optical simulations to evaluate thermal aberrations in the wavefront.

[0065] There are two thermomechanical mechanisms that can degrade the optical performance of stamped mirrors used in high power applications. The first mode is transient thermal phenomena that can occur with pulsed lasers, and the second mode is steady-state phenomena that can occur with continuous wave (CW) lasers. These phenomena are:

[0066] a. damage to the mirror surface due to short pulses of high peak power, which can lead to local but very high transient temperature increases, and

[0067] b. Thermal aberrations due to thermal expansion and the change in the form of the reflecting surface when light power is absorbed into the mirror and causes the temperature to rise.

[0068] Both phenomena are analyzed for optical designs with two alternative materials. Results for a mirror stamped from high purity 4N aluminum are compared to a mirror made by injection molding using a PEI polymer. In both cases, the mirror is assumed to be coated to achieve 99% reflectivity at the operating wavelength. Finite element analysis (FEA) is performed for both transient pulse phenomena and steady state (static) phenomena. Fig.8D is a schematic diagram showing heat transfer from the mirror array block to the substrate and the environment. Fig.8D As shown, the corresponding mirror array block (aluminum vs polymer) is assumed to be mounted to a thermally conductive substrate made of 2mm thick aluminum alloy with thermally conductive contact between the mirrors and the substrate. All surfaces are set to free convection to ambient air at a temperature of 20°C. The incident laser beam is modeled as a heat flux equal to 1% of the total laser power.

[0069] For the transient case of a pulsed laser, the laser is assumed to produce 5kW peak optical power, with a repetition rate of 1kHz, a duty cycle of 0.05%, and a pulse width of 500ns. This is representative of lasers used in LiDAR applications. A single cycle (pulse followed by cooling) is simulated as a 500ns laser pulse followed by 0.9995 ms of cooling. During the pulse, the incident heat flux from the laser is set to a 50W (1% absorption of the 5kW laser power) incident flux onto the mirror. Comparing the response of the aluminum mirror and the polymer mirror, the aluminum mirror shows a much lower peak temperature of 65°C compared to the peak temperature of the polymer (reaching 237°C during the single pulse exposure). In this case, the center of the polymer mirror reaches a temperature of 210°C above its glass transition temperature, which will definitely cause permanent damage and aberrations. In contrast, the peak temperature of 65°C on the aluminum mirror is still well within its safe range operating range limited by the damage threshold (such as the melting temperature of 660°C). Furthermore, due to the much higher thermal diffusivity, the aluminum mirror returns to the ambient temperature of 20°C at the end of the cycle. The polymer mirror, on the other hand, cools much slower and still has a temperature close to 39°C at the start of the next pulse.

[0070] For the steady-state case where thermal aberrations are caused when thermal expansion occurs during temperature rise, a constant heat flux of 0.01 Watt is assumed for a 1 Watt CW beam incident on a 99% reflective coating of the mirror. The steady-state temperature distribution within the mirror is observed for the polymer mirror and the aluminum mirror. For the time to reach the equilibrium temperature of the two mirrors, the polymer mirror reaches a much higher temperature in the hole area, and it has a larger temperature gradient across the surface of the mirror. These temperature distributions cause thermoelastic deformations due to the CTE of the materials.

[0071] The shape of the mirror at equilibrium is exported from the FEA software as a 3D mesh and then input into the ray tracing software. The beam propagation is used to calculate the optical results as a distortion of the wavefront. To validate the technique, the wavefront of the original mirror is checked using the mesh geometry. The results for the faceted mesh of the original mirror (without thermal aberration) are negligible with only about 0.02 waves of distortion from a perfectly flat wavefront across the beam. The wavefront distortion is due to thermal aberrations of the stamped aluminum mirror. The thermal aberrations and changes in beam propagation direction are significantly worse for the polymer mirror. The wavefront before adjusting for errors in beam propagation direction is about twice that of the aluminum wavefront. The wavefront of the polymer mirror with distortion in a collimated beam is about five times that of the aluminum mirror wavefront.

[0072] Fig. 8Eis an alternative reflector array block MB' according to another embodiment of the present invention. In this embodiment, the reflector array block MB' has a composite structure. The array of free-form reflectors M" is integrally and simultaneously defined on a monolithic block of metal (e.g., 4N Al) B' within a low CTE metal frame CF of different materials by a metal stamping process to improve thermal expansion effects. The frame CF can be made of Kovar / Invar. The outer frame CF covers the surfaces of the monolithic block except for the angled surfaces defined by the reflectors M". The reflectors M" are formed with similar design considerations to the previous embodiments. The frame CF is attached to the substrate S to replace Figure 8B The reflector array block MB in FIG.

[0073] In another embodiment of the present invention, an alternative method to improve the roundness of the output beam is to collimate the slow axis and the fast axis separately at different positions. Fig.9A is a schematic perspective layout of two complementary mirror array blocks for steering and shaping (collimation) of multiple laser beams according to one embodiment of the present invention. Fig.9A As shown, the mirror array includes two stamped mirror array blocks MB1 and MB2 in the form of a metal optical bench (MOB), each of which has a set of mirrors to achieve overall slow-axis collimation, fast-axis collimation, and beam folding / steering. Fig.9A As depicted in , there are three lasers L, but in Fig.9A Only one is visible in the view in . The other two lasers are each between two sub-blocks of mirror M2. Fig.9A The mirror array configuration in can be incorporated into a hermetically sealed LBM package (e.g., including a frame, a cover, and a substrate, as in the previously discussed embodiments (e.g., Fig. 8A )

[0074] In this embodiment, the fast axis of the laser beam from laser L is first collimated and reflected sideways by three free-form aspheric cylindrical mirrors M1 on mirror array block MB1. Then, the slow axis of the laser beam is collimated and the laser beam is folded upward by another set of free-form aspheric cylindrical mirrors M2 on mirror array block M2. The beam profile and residual wavefront of the collimated beam are respectively Fig. 9B and 9C Shown in. Fig. 9B Schematically depicts an optical simulation of a beam profile at a target plane at a reference distance (e.g., at 10 mm from the laser L); Fig. 9C Schematically depicted the optical simulation of the residual wavefront of a collimated beam at the target plane at a reference distance.

[0075] exist Fig.9AIn the embodiment, the second reflector array block MB2 is schematically shown as three separate sub-blocks to avoid shielding the reflective surface of the reflector M2. It should be understood that two or more sub-blocks may be included in a single integral / monoblock without departing from the scope and spirit of the present invention. Fig.9A In the embodiment, the first reflector array block MB1 and the second reflector array block MB2 are schematically shown as two separate sub-blocks to avoid blurring the understanding of the structure. It should be understood that the two reflector array blocks MB1 and MB2 can be included in a single integral / monoblock without departing from the scope and spirit of the present invention.

[0076] In this embodiment, if the fast-axis collimating mirror M1 and the slow-axis collimating mirror M2 are integrated into a single component (i.e., the mirror array block MB2 is integrated into a single monolithic component), then the optical alignment of the mirrors M1 and M2 can be achieved through a precision stamping process. In essence, for each laser beam, two aspheric mirrors are integrated into a single stamped optical stage to collimate and beam shape the light from the corresponding laser. During assembly, no active alignment is required between the slow-axis mirror M1 and the fast-axis mirror M2. This improves cost and reliability by eliminating adhesive joints and curing operations.

[0077] Fig. 10A is a schematic perspective layout of two complementary mirror array blocks for steering, shaping, redirecting and combining multiple laser beams at a target plane at a reference distance (e.g., a distance of 30 mm from the height of the laser L) according to one embodiment of the present invention. Fig. 10A As shown, the mirror array includes two stamped mirror array blocks MB1' and MB2' in the form of metal optical tables (MOBs), each of which has a set of mirrors to achieve overall slow-axis collimation, fast-axis collimation, and beam folding and redirection to combine the beams at a target plane. Fig. 10B Schematically depicts the beam overlap of the laser beams at the target plane at a reference distance. Fig. 10A As depicted in , there are three lasers L, but in Fig. 10A Only one is visible in the view in . The other two lasers are each between two sub-blocks of mirrors M2'. Fig. 10A The mirror array configuration in can be incorporated into a hermetically sealed LBM package (e.g., including a frame, a cover, and a substrate, as in the previously discussed embodiments (e.g., Fig. 8A )

[0078] In this embodiment, the fast axis of the laser beam from the laser L is first collimated and reflected sideways by three free-form aspheric cylindrical mirrors M1' on the mirror array block MB1'. For this set of mirrors M1', it can have a reflection profile similar to the reflection profile of the set of mirrors M1 in the previous embodiment. Then, the slow axis of the laser beam is collimated, and the laser beam is folded upward and redirected by another set of free-form aspheric cylindrical mirrors M2' on the mirror array block M2'. The beam profile of the collimated beam is Fig. 10B , showing the three beams at the reference target plane tp with 1 / e 2 Intensity beams overlap.

[0079] exist Fig. 10A In the embodiment of the present invention, the second reflector array block MB2' is schematically shown as three separate sub-blocks to avoid shielding the reflective surface of the reflector M2'. It should be understood that two or more sub-blocks may be included in a single integral / monoblock without departing from the scope and spirit of the present invention. Fig. 10A In the embodiment, the first reflector array block MB1' and the second reflector array block MB2' are schematically shown as two separate sub-blocks to avoid blurring the understanding of the structure. It should be understood that the two reflector array blocks MB1' and MB2' can be included in a single integral / monoblock without departing from the scope and spirit of the present invention.

[0080] In this embodiment, if the fast-axis collimating mirror M1' and the slow-axis collimating mirror M2' are integrated into a single component (i.e., the mirror array block MB2' is integrated into a single monolithic component), the optical alignment of the mirrors M1' and M2' can be achieved through a precision stamping process. In essence, for each laser beam, two aspheric mirrors are integrated into a single stamped optical stage to collimate and beam shape the light from the corresponding laser. Active alignment between the slow-axis mirror M1' and the fast-axis mirror M2' will not be required during assembly. This improves cost and reliability by eliminating adhesive joints and curing operations.

[0081] As can be further appreciated, further improvements in size, weight, reliability, and cost can be achieved if the RGB beams are combined without the use of a dichroic filter assembly. The stamped mirror array of the present invention essentially applies rigid body rotation of two sets of mirror surfaces to overlap the beams at a desired location (e.g., a scanning mirror for an XR application), thereby eliminating any need for a separate dichroic filter assembly.

[0082] Although the present invention has been described with reference to illustrated embodiments of aspherical reflective surfaces as examples of free-form reflective surfaces, other free-form reflective optical surfaces may be employed without departing from the scope and spirit of the present invention.

[0083] Although the present invention has been specifically shown and described with reference to preferred embodiments, it will be appreciated by those skilled in the art that various changes may be made in form and detail without departing from the spirit, scope and teachings of the present invention. Therefore, the disclosed invention is considered to be illustrative only and limited only to the scope specified in the appended claims.

Claims

1. A laser beam module package, comprising: a laser array that outputs an incident laser beam having an elliptical cross-sectional beam profile due to astigmatism of the incident laser beam; a housing having a base plate supporting a frame having a top side, wherein the housing has a space defined by the frame, the space receiving the laser array and supporting the laser array on the base plate within the space; an optically transparent cover hermetically sealed to the top side of the frame; and A reflector array, the reflector array comprising a reflector body of metal material, the reflector body having a plurality of reflectors, the plurality of reflectors being defined on the surface of the reflector body by metal stamping the surface of the reflector body to form an array of smooth free-form reflective surfaces of the reflector array, wherein the reflector body is supported by the housing and housed within a space of the housing, wherein the reflector array is optically aligned with the laser array, wherein the free-form reflective surface is configured to reflect and shape a beam profile of a corresponding incident laser beam to generate a corresponding output laser beam, the corresponding output laser beam being directed toward the cover to be output from the laser beam module package.

2. The laser beam module package according to claim 1, wherein: The free-form reflective surface is configured to correct astigmatism of the laser beam to produce an output laser beam that is more closely aligned with a collimated beam.

3. The laser beam module according to claim 2, wherein: The reflector body is supported by the substrate and / or the frame.

4. The laser beam module package according to any one of claims 1 to 3, wherein: The reflector body comprises a monolithic block of metallic material, wherein the reflectors are defined by stamping a surface of the monolithic block to integrally and simultaneously form the plurality of reflectors, and wherein the reflectors are defined on a surface of the reflector body facing a corresponding laser in the laser array.

5. The laser beam module package according to claim 4, wherein: The monolithic block is a base that is structurally coupled to the frame, wherein the base is inserted through an opening in the frame, wherein the base is structurally coupled to the frame when stamped to define the reflector on the body.

6. The laser beam module package according to claim 5, wherein: The base surrounds an inner wall of the opening in the frame, thereby defining an opening in the reflector body to receive the laser array.

7. The laser beam module package according to claim 4, wherein: The reflector body comprises a reflector array block having a bottom surface for attachment to the substrate and an angled surface facing the laser array, wherein the reflector array block comprises the monolithic block, and wherein the reflector is defined by stamping the angled surface of the monolithic block to integrally and simultaneously form the plurality of reflectors prior to attaching the bottom surface of the reflector array block to the substrate.

8. The laser beam module package according to claim 7, wherein: The reflector array block further includes an outer frame covering a surface of the monolithic block other than the angled surface, wherein the frame defines a bottom surface of the reflector array block for attachment to the substrate.

9. The laser beam module package according to any one of the preceding claims, wherein: The base plate and the frame are separate components made of different materials, and wherein the frame is hermetically sealed to the base plate.

10. The laser beam module package according to any one of the preceding claims, wherein: The housing is made of a first material and the mirror body is made of a second material; wherein the second material is different from the first material.

11. The laser beam module package according to any one of the preceding claims, wherein: The reflector array includes a first reflector array and a second reflector array, the first reflector array includes a first group of free-form reflectors, the second reflector array includes a second group of free-form reflectors corresponding to and facing the first group of reflectors, wherein an incident laser beam is directed to the first group of reflectors, wherein the first group of reflectors collimates and reflects the incident laser beam to the second group of reflectors, wherein the second group of reflectors further collimates and directs the collimated output laser beam to the cover to be output from the laser beam module package.

12. The laser beam module package according to any one of claims 1 to 5, wherein: The first group of mirrors are free-form aspheric cylindrical mirrors and the second group of mirrors are free-form aspheric cylindrical mirrors.

13. The laser beam module package according to any one of the preceding claims, wherein: The free-form reflective surface of the mirror array is configured to converge the output laser beam into a spot at a target plane at a reference distance from the laser beam module package.

14. The laser beam module package according to any one of the preceding claims, wherein: The reflector is a concave aspherical reflective surface of the reflector body.

15. A method of assembling a laser beam module package as claimed in any preceding claim, comprising stamping to form the free form reflective surface in the mirror array.

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