Laser beam expander

Abstract

The utility model relates to the technical field of laser equipment, and provides a laser beam expander, which comprises a seat body, a laser transmitter and a beam expander lens, the beam expanding lens comprises a first lens barrel which comprises a light inlet end and a light outlet end, and the inner diameter of the first lens barrel is gradually increased in the direction from the light inlet end to the light outlet end; the optical axis of the lens group coincides with the central axis of the first lens cone, the lens group comprises a first lens, a second lens and a third lens which are arranged in sequence, the first lens is arranged in the light inlet end, a first adhesive layer is arranged in the light outlet end, and the second lens and the third lens are arranged in the light outlet end and fixedly adhered to the first adhesive layer. The second lens and the third lens can be directly bonded and fixed in the light emitting end of the first lens barrel through the first adhesive layer, other connecting structures are not needed, the size and the weight of the laser beam expander are reduced, and the laser beam expander is smaller in size and lighter in weight.

Description

Technical Field

[0001] The utility model relates to the technical field of laser equipment, and more specifically to a laser beam expander. Background Art

[0002] Laser beam expander is a device that expands the diameter of laser beam and reduces the divergence angle of laser beam. Therefore, it is used in long-distance lighting or projection, as well as focusing system.

[0003] For laser beam expanders, it is necessary to consider the optical system design as well as the assembly structure of the beam expander. The optical system design can improve the values ​​of optical indicators such as beam expansion ratio and transmittance. However, from the perspective of the assembly structure, the existing technology generally has the problem that the overall size of the beam expander is large and bulky.

[0004] Therefore, the existing technology still needs to be improved and developed. Summary of the invention

[0005] The utility model aims to provide a laser beam expander to solve the technical problem of the overall size of the beam expander in the prior art being relatively large.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the utility model is: to provide a laser beam expander, comprising a base body and a laser emitter and a beam expander lens connected to the base body;

[0007] The beam expander lens comprises:

[0008] A first lens barrel, comprising a light-input end and a light-output end, wherein the inner diameter of the first lens barrel gradually increases in a direction from the light-input end to the light-output end;

[0009] A lens group, wherein the optical axis of the lens group coincides with the central axis of the first lens barrel, the lens group comprises a first lens, a second lens and a third lens arranged in sequence, the first lens is arranged in the light input end, a first adhesive layer is provided in the light output end, the second lens and the third lens are arranged in the light output end and are bonded and fixed on the first adhesive layer.

[0010] Furthermore, a first positioning portion is provided on the inner wall of the light-emitting end, the first adhesive layer is provided on the first positioning portion, and the second lens and the third lens are abutted and bonded to the first positioning portion.

[0011] Furthermore, the inner wall of the light emitting end is concave inwardly along the circumferential direction and forms the first positioning portion, the first positioning portion includes a first step portion and a second step portion, the inner diameter of the first step portion is smaller than the inner diameter of the second step portion, the first step portion and the second step portion constitute a stepped table top and are both provided with the adhesive layer, the edge of the second lens is stopped and bonded to the first step portion, and the edge of the third lens is stopped and bonded to the second step portion.

[0012] In some embodiments, a second lens barrel is further included, the first lens is arranged in the second lens barrel, the second lens barrel is provided with an external thread, the light input end is provided with a mounting hole with an internal thread, the second lens barrel is screwed in the mounting hole and is suitable for screwing in or out of the mounting hole.

[0013] Furthermore, the first lens is a double concave lens, the second lens and the third lens are positive meniscus lenses, the concave surfaces of the second lens and the third lens are light-incoming surfaces, and the convex surfaces of the second lens and the third lens are light-emitting surfaces.

[0014] In some embodiments, the air gap between the second lens and the third lens is 0.4 mm-0.6 mm.

[0015] Furthermore, the first lens, the second lens and the third lens are all coated with an anti-reflection film, and the transmittance of the first lens, the second lens and the third lens is not less than 90%, and the surface tolerance is less than 20nm.

[0016] In some embodiments, the length of the beam expander lens is no more than 30 mm, and the length of the laser beam expander is no more than 70 mm.

[0017] Furthermore, a flange is provided on the outer periphery of the light emitting end, a connecting portion is provided on the base body, a through hole and a fixing hole surrounding the through hole are provided on the connecting portion, at least a portion of the light emitting end is accommodated in the through hole, and the flange is stopped on the connecting portion and is connected and fixed to the fixing hole by fasteners.

[0018] In some embodiments, the base body is symmetrically provided with a first positioning protrusion and a second positioning protrusion on both sides along the length direction, the laser emitter is clamped and fixed between the first positioning protrusion and the second positioning protrusion, and the light outlet of the laser emitter faces the light inlet end of the first lens barrel.

[0019] The beneficial effect of the laser beam expander provided by the present invention is at least that: the second lens and the third lens of the present application can be directly bonded and fixed in the light-emitting end of the first lens barrel through the first adhesive layer, and there is no need to set up other connecting structures. Compared with the above-mentioned fixing method through threaded rings or buckles, it is equivalent to eliminating the volume share of threaded rings and buckles, simplifying the volume and weight of the laser beam expander. The volume size of the laser beam expander of the present application is smaller and lighter. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of the three-dimensional structure of a laser beam expander provided in an embodiment of the present application;

[0022] Figure 2 for Figure 1 Schematic diagram of the three-dimensional structure of the laser beam expander at another angle;

[0023] Figure 3 for Figure 1 A schematic diagram of the three-dimensional structure of the laser beam expander at another angle;

[0024] Figure 4 A schematic diagram of the three-dimensional structure of the laser beam expander provided in an embodiment of the present application when no laser emitter is installed;

[0025] Figure 5 for Figure 4 The cross-sectional view of the laser beam expander in the AA direction;

[0026] Figure 6 for Figure 4 Schematic diagram of the three-dimensional structure of the laser beam expander at another angle;

[0027] Figure 7 for Figure 4 Schematic diagram of the three-dimensional structure of the laser beam expander at another angle.

[0028] Among them, the reference numerals in the figure are:

[0029] 1. Laser beam expander;

[0030] 2. seat body; 21. connection part; 22. through hole; 23. fixing hole; 24. first positioning protrusion; 25. second positioning protrusion;

[0031] 3. Laser transmitter;

[0032] 4. Beam expansion lens;

[0033] 41. first lens barrel; 411. light inlet end; 412. light outlet end; 413. mounting hole; 414. flange;

[0034] 42. first lens; 43. second lens; 44. third lens; 45. first adhesive layer;

[0035] 46, first positioning portion; 461, first step portion; 462, second step portion;

[0036] 47. Second lens barrel. DETAILED DESCRIPTION

[0037] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0038] It should be noted that when a component is referred to as being "fixed on" or "disposed on" another component, it may be directly or indirectly located on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The directions or positions indicated by the terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the accompanying drawings and are only for the convenience of description and cannot be understood as limitations on the present technical solution. The terms "first" and "second" are only used for the convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0039] The laser beam expander according to the embodiment of the utility model is described below in conjunction with the accompanying drawings.

[0040] See also Figure 1-Figure 3 , Figure 1 The schematic diagram of the three-dimensional structure of the laser beam expander 1 of the present application is shown. The laser beam expander 1 includes a base 2 and a laser emitter 3 and a beam expander lens 4 connected to the base 2. The laser emitter 3 is used to emit a laser beam to the beam expander lens 4, and the beam expander lens 4 is used to expand the laser beam, including diffusing the diameter of the laser beam and reducing the divergence angle of the laser beam.

[0041] Further, see Figure 1-Figure 5The collimator lens 4 includes a first lens barrel 41 and a lens group arranged in the first lens barrel 41. The first lens barrel 41 is a metal or plastic cylinder for fixing the lens group. The inner diameter of the first lens barrel 41 matches the caliber of the lens group. The length of the first lens barrel 41 varies depending on the focal length of the collimator lens 4. In other words, the spacing of the lens groups in the first lens barrel 41 affects the focal length of the collimator lens 4.

[0042] Specifically, see Figure 4 and Figure 5 The first lens barrel 41 includes a light input end 411 and a light output end 412. The inner diameter of the first lens barrel 41 gradually increases from the light input end 411 to the light output end 412. That is to say, the first lens barrel 41 is constructed as a horn, and the inner diameter of the light input end 411 is smaller than the inner diameter of the light output end 412, which just fits the scenario in which the beam expander lens 4 expands the laser beam. In addition, in order to improve the accuracy of beam expansion, the optical axis of the lens group coincides with the central axis of the first lens barrel 41.

[0043] Continue reading Figure 5 The lens group includes a first lens 42, a second lens 43 and a third lens 44 which are arranged in sequence. The first lens 42 is arranged in the light inlet end 411, and a first adhesive layer 45 is arranged in the light outlet end 412. The second lens 43 and the third lens 44 are arranged in the light outlet end 412 and are bonded and fixed on the first adhesive layer 45. It should be noted that the light inlet end 411 and the light outlet end 412 refer to the two ends of the first lens barrel 41. The laser beam emitted by the laser emitter 3 enters the first lens barrel 41 from the light inlet end 411. The laser beam is expanded after passing through the first lens 42, the second lens 43 and the third lens 44 in sequence in the first lens barrel 41. The expanded laser beam is emitted from the light outlet end 412.

[0044] Among them, the lens of the laser beam expander 1 in the related art is fixed on the first lens barrel 41 by a threaded ring, or the lens is fixed on the first lens barrel 41 by a buckle. No matter which of the above methods is used for connection, the threaded ring and the buckle need to occupy a part of the space. When the lens size is the same, the volume of the beam expander will be enlarged, which will cause the overall size of the laser beam expander 1 to be larger and heavier. The second lens 43 and the third lens 44 of the present application can be directly bonded and fixed in the light output end 412 of the first lens barrel 41 through the first adhesive layer 45, without the need to set other connection structures. Compared with the above-mentioned fixing method through the threaded ring or buckle, it is equivalent to eliminating the volume share of the threaded ring and the buckle, simplifying the volume and weight of the laser beam expander 1, and the volume size of the laser beam expander 1 of the present application is smaller and lighter.

[0045] At the same time, each lens of the lens group is a lens, and each lens is arranged at intervals to form a combined lens. The combined lens is used to expand the laser beam, and its beam expansion ratio is higher than that of a single lens. Compared with setting a single lens, a lens group composed of multiple lenses is also easier to correct spherical aberration.

[0046] Further, the first adhesive layer 45 is composed of an adhesive attached to the inner wall of the first lens barrel 41 (light output end 412), and the adhesive includes but is not limited to any one of polyurethane adhesive, epoxy resin adhesive, and phenolic resin adhesive or a combination thereof, so as to be able to bond and fix the second lens 43 and the third lens 44 to the inner wall of the first lens barrel 41. The adhesive can switch between a fluid and a solid state. For example, the epoxy resin adhesive is in a fluid state after heating and solidifies into a solid state at room temperature.

[0047] When installing the second lens 43 and the third lens 44, the adhesive is processed into a fluid form by heating or other means and coated on the inner wall of the first lens barrel 41, and then the edges of the second lens 43 and the third lens 44 are abutted against the position where the adhesive is coated on the first lens barrel 41. The adhesive forms a first adhesive layer 45 after curing. In this way, the second lens 43 and the third lens 44 can be bonded and fixed to the inner wall of the first lens barrel 41 (light output end 412) through the first adhesive layer 45.

[0048] In some embodiments, to facilitate the installation of the second lens 43 and the third lens 44, refer to Figure 5 A first positioning portion 46 is provided on the inner wall of the light-emitting end 412, a first adhesive layer 45 is provided on the first positioning portion 46, and the second lens 43 and the third lens 44 are abutted and bonded to the first positioning portion 46. The first positioning portion 46 is a structural body provided on the inner wall of the first lens barrel 41 (light-emitting end 412), and can be a convex block protruding from the inner wall of the first lens barrel 41, or a trapezoidal groove recessed in the inner wall of the first lens barrel 41.

[0049] The purpose of setting the first positioning portion 46 is to provide a positioning function for the installation of the second lens 43 and the third lens 44. It can be understood that when installing the second lens 43 and the third lens 44, the second lens 43 and the third lens 44 need to be placed into the first lens barrel 41 from the light-emitting end 412. After the first positioning portion 46 is set, the second lens 43 and the third lens 44 will stop on the first positioning portion 46 during the placement process, so that the positioning installation can be directly achieved. In addition, the first adhesive layer 45 is set on the first positioning portion 46. When the second lens 43 and the third lens 44 stop on the first positioning portion 46, they can be directly bonded to the adhesive layer, so that the installation accuracy of the second lens 43 and the third lens 44 is higher and the assembly process is more convenient.

[0050] Furthermore, the first positioning portion 46 is configured as a trapezoidal groove, see Figure 5 The inner wall of the light-emitting end 412 is concave inward along the circumferential direction and forms a first positioning portion 46. The first positioning portion 46 includes a first step portion 461 and a second step portion 462. The inner diameter of the first step portion 461 is smaller than the inner diameter of the second step portion 462. The first step portion 461 and the second step portion 462 form a stepped table and are both provided with an adhesive layer. The edge of the second lens 43 is stopped and bonded to the first step portion 461, and the edge of the third lens 44 is stopped and bonded to the second step portion 462. In the direction from the light-input end 411 to the light-emitting end 412, the inner diameter of the first lens barrel 41 at the light-emitting end 412 increases in a stepped manner. At the same time, the diameter of the third lens 44 is larger than the diameter of the second lens 43.

[0051] When installing the second lens 43 and the third lens 44, the second lens 43 is now placed into the first lens barrel 41 from the light-emitting end 412. The second lens 43 will pass through the position of the second step portion 462 and adhere to the first step portion 461. The second step portion 462 will not block the installation of the second lens 43. Then, the third lens 44 is placed into the first lens barrel 41 from the light-emitting end 412. The third lens 44 stops and adheres to the second step portion 462.

[0052] Furthermore, the first positioning portion 46 is an annular groove that is concave along the circumference of the first lens barrel 41, and the second lens 43 and the third lens 44 are both circular lenses. The end face edges of the second lens 43 and the third lens 44 can be directly bonded to the first positioning portion 46 to improve the firmness after bonding.

[0053] Of course, the first positioning portion 46 can also be set as a protrusion (not shown in the figure), which is arranged on the inner wall of the first lens barrel 41 along the circumference of the first lens barrel 41, and the protrusion includes a first boss and a second boss. The cross-section of the protrusion is a trapezoidal table top, and the protrusion height of the first boss is higher, that is, compared with the second boss, the first boss is farther away from the inner wall of the first lens barrel 41, and the first adhesive layer 45 is provided on the first boss and the second boss, the second lens 43 is stopped and bonded to the first boss, and the third lens 44 is stopped and bonded to the second boss.

[0054] In some embodiments, to facilitate adjustment of the beam expansion ratio of the first lens barrel 41, refer to Figure 2-Figure 6 The laser beam expander 1 further includes a second lens barrel 47, the first lens 42 is disposed in the second lens barrel 47, the second lens barrel 47 is provided with an external thread, the light inlet end 411 is provided with a mounting hole 413 with an internal thread, and the second lens barrel 47 is screwed into the mounting hole 413 and is suitable for screwing into or out of the mounting hole 413. The second lens barrel 47 is used to adjust the position of the first lens 42 on the optical axis, that is, to adjust the distance between the first lens 42 and the second lens 43, thereby achieving different beam expansion ratios.

[0055] After the first lens 42 is installed in the second lens barrel 47, the second lens barrel 47 is screwed into the mounting hole 413 of the first lens barrel 41 to complete the assembly of the second lens barrel 47 and the first lens barrel 41. When the beam expansion magnification of the laser beam expander 1 needs to be adjusted, the second lens barrel 47 is screwed in and out of the mounting hole 413 to adjust the distance between the first lens 42 and the second lens 43, thereby achieving the effect of adjusting the beam expansion magnification, which is easy to operate.

[0056] Furthermore, a second adhesive layer (not shown) is provided in the second lens barrel 47, and the first lens 42 is fixed in the second lens barrel 47 by the second adhesive layer. Similar to the first adhesive layer 45 provided in the first lens barrel 41, the first lens 42 is also fixed in the second lens barrel 47 by bonding, thereby reducing the number of connecting parts 21, thereby achieving the effect of streamlining the volume of the second lens barrel 47, and the size of the second lens barrel 47 can be set to be smaller and lighter.

[0057] Further, similar to the first positioning portion 46, a second positioning portion (not shown) is provided in the second lens barrel 47, the second positioning portion has a third step portion, the second adhesive layer is provided on the third step portion, and after the first lens 42 is placed in the second lens barrel 47, the first lens 42 stops and adheres to the third step portion. The provided second positioning portion can play a role in positioning the installation of the first lens 42, improve the installation accuracy of the first lens 42, and make the assembly process more convenient.

[0058] Among them, the second positioning portion is a convex block protruding from the second lens barrel 47 and arranged around the inner wall of the second lens barrel 47. The convex block and the inner wall of the second lens barrel 47 are configured into a step-type structure. After the first lens 42 is placed in the second lens barrel 47, the edge of the first lens 42 is adapted to the inner wall of the second lens barrel 47, and the end face edges of the first lens 42 can all stop on the second positioning portion, thereby achieving the effect of improving the connection firmness.

[0059] In some embodiments, in order to increase the beam expansion ratio and reduce the spherical aberration, the first lens 42 of the lens group is a biconcave lens. The first lens 42 is set as a biconcave lens, which can have a good beam expansion effect on the laser beam, and compared with the plano-concave lens, the biconcave lens has a larger beam expansion ratio.

[0060] The second lens 43 and the third lens 44 are set as meniscus lenses, and a combined lens is formed by two meniscus lenses and a double concave lens. The second lens 43 and the third lens 44 cooperate to form an air gap doublet lens. The air gap doublet lens can correct the spherical aberration of the laser beam after the beam expansion by the double concave lens. After the laser beam passes through the second lens 43 and the third lens 44, that is, after being corrected by the two meniscus lenses, the spherical aberration correction effect of the laser beam is better.

[0061] It should be noted that the above-mentioned spherical aberration correction effect is better relative to correction through a meniscus lens. When the standards of the biconcave lens and the meniscus lens used are the same, after comparative experiments, the convergent spot size of a single biconcave lens is 240μm, the convergent spot size of a single biconcave lens plus a meniscus lens is 81μm, and the convergent spot size of a single biconcave lens plus two meniscus lenses is only 21μm. Therefore, the lens set of the present application has a good spherical aberration correction effect.

[0062] Exemplarily, the second lens 43 and the third lens 44 are positive meniscus lenses, the concave surfaces of the second lens 43 and the third lens 44 are light-incoming surfaces, and the convex surfaces of the second lens 43 and the third lens 44 are light-outgoing surfaces. That is to say, after passing through the first lens 42, the laser beam enters the second lens 43 from the concave surface of the second lens 43, and then is emitted from the convex surface of the second lens 43, thereby realizing the first spherical aberration correction, and then the laser beam enters the third lens 44 from the concave surface of the third lens 44, and then is emitted from the convex surface of the third lens 44, thereby realizing the second spherical aberration correction.

[0063] Furthermore, the air gap between the second lens 43 and the third lens 44 is 0.4 mm-0.6 mm. In layman's terms, the distance between the second lens 43 and the third lens 44 is 0.4 mm-0.6 mm. A smaller air gap allows the overall size of the laser beam expander 1 to be set smaller.

[0064] Furthermore, in order to improve the transmittance of the lens group, the first lens 42, the second lens 43 and the third lens 44 are all coated with an anti-reflection film, and the transmittance of the first lens 42, the second lens 43 and the third lens 44 is not less than 90%, and the surface tolerance is less than 20nm. The laser beam expander 1 can achieve high-magnification beam expansion while ensuring high transmittance, and the lens group has good surface quality, thereby improving the overall beam expansion effect of the laser beam expander 1.

[0065] Based on the arrangement of the lens group in the above-mentioned embodiment, under the premise of achieving the same beam expansion ratio, the laser beam expander 1 of the present application can be arranged to be more compact, and a clearer image with better focusing effect can be obtained.

[0066] The length of the beam expander lens 4 is not more than 30 mm, and the length of the laser beam expander 1 is not more than 70 mm. Therefore, the laser beam expander 1 of the present application has a high beam expansion ratio and transmittance, and also has a compact size and lighter weight, which is more convenient to carry while meeting the functionality.

[0067] In some embodiments, the laser beam expander 1 of the present application can achieve overall size reduction not only through the beam expander lens 4, but also through the base 2. Figure 1-Figure 7A flange 414 is provided on the outer periphery of the light emitting end 412, a connecting portion 21 is provided on the base body 2, a through hole 22 and a fixing hole 23 surrounding the through hole 22 are provided on the connecting portion 21, at least a portion of the light emitting end 412 is accommodated in the through hole 22, and the flange 414 is stopped on the connecting portion 21 and is connected and fixed to the fixing hole 23 through fasteners.

[0068] When the beam expander lens 4 is mounted on the base 2, the light emitting end 412 is extended into the through hole 22, and the flange 414 is abutted and screwed to the connecting portion 21, thereby fixing the beam expander lens barrel on the base 2. Among them, since at least a portion of the light emitting end 412 is accommodated in the through hole 22, that is, the through hole 22 can provide an escape channel for the light emitting end 412, when the beam expander lens 4 is mounted on the base 2, it is no longer necessary to provide additional installation space for the light emitting end 412, so it is equivalent to offsetting a portion of the volume of the light emitting end 412, thereby achieving the effect of reducing the volume of the laser beam expander 1.

[0069] Combined with the through hole 22 on the base 2 and the mounting structure of the lens assembly, the volume and size of the laser beam expander 1 can be further reduced.

[0070] Further, see Figure 1-Figure 7 The base body 2 is symmetrically provided with a first positioning protrusion 24 and a second positioning protrusion 25 on both sides along the length direction. The laser emitter 3 is clamped and fixed between the first positioning protrusion 24 and the second positioning protrusion 25. The light outlet of the laser emitter 3 faces the light inlet end 411 of the first lens barrel 41.

[0071] The first positioning protrusion 24 includes a first positioning protrusion and a first cushion block, the first cushion block is an elastic block arranged on the top of the first positioning protrusion, and the second positioning protrusion 25 includes a second positioning protrusion and a second cushion block, the second cushion block is an elastic block arranged on the top of the second positioning protrusion. The laser emitter 3 is placed on the base 2 and is located between the first positioning protrusion and the second positioning protrusion. The first cushion block and the second cushion block clamp the laser emitter 3 through elastic action, thereby fixing the laser emitter 3 on the base, firmly installing it while improving assembly efficiency.

[0072] Furthermore, both sides of the laser emitter 3 along the length direction are provided with a card slot, and the first positioning protrusion 24 and the second positioning protrusion 25 are engaged in the card slot. Among them, at least the first cushion block and the second cushion block are engaged in the card slot, and the laser emitter 3 is not only positioned and installed by clamping, but also the first positioning protrusion 24 and the second positioning protrusion 25 cooperate with the card slot, which can reduce the risk of displacement of the laser emitter 3 relative to the base 2, and further improve the stability of the laser emitter 3 after positioning and installation.

[0073] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser beam expander, characterized in that: It comprises a base body, a laser emitter and a beam expander lens connected to the base body; The beam expander lens comprises: A first lens barrel, comprising a light-input end and a light-output end, wherein the inner diameter of the first lens barrel gradually increases in a direction from the light-input end to the light-output end; A lens group, wherein the optical axis of the lens group coincides with the central axis of the first lens barrel, the lens group comprises a first lens, a second lens and a third lens arranged in sequence, the first lens is arranged in the light input end, a first adhesive layer is provided in the light output end, the second lens and the third lens are arranged in the light output end and are bonded and fixed on the first adhesive layer.

2. The laser beam expander according to claim 1, characterized in that: The inner wall of the light-emitting end is provided with a first positioning portion, the first adhesive layer is arranged on the first positioning portion, and the second lens and the third lens are abutted and bonded to the first positioning portion.

3. The laser beam expander according to claim 2, characterized in that: The inner wall of the light emitting end is concave along the circumferential direction and forms the first positioning portion, the first positioning portion includes a first step portion and a second step portion, the inner diameter of the first step portion is smaller than the inner diameter of the second step portion, the first step portion and the second step portion constitute a stepped table surface and are both provided with the first adhesive layer, the edge of the second lens is stopped and bonded to the first step portion, and the edge of the third lens is stopped and bonded to the second step portion.

4. The laser beam expander according to claim 2, characterized in that: It also includes a second lens barrel, the first lens is arranged in the second lens barrel, the second lens barrel is provided with external threads, the light inlet end is provided with a mounting hole with internal threads, the second lens barrel is screwed in the mounting hole and is suitable for screwing in or out of the mounting hole.

5. The laser beam expander according to claim 1, characterized in that: The first lens is a double concave lens, the second lens and the third lens are positive meniscus lenses, the concave surfaces of the second lens and the third lens are light-incoming surfaces, and the convex surfaces of the second lens and the third lens are light-outgoing surfaces.

6. The laser beam expander according to claim 1, characterized in that: The air gap between the second lens and the third lens is 0.4 mm-0.6 mm.

7. The laser beam expander according to claim 1, characterized in that: The first lens, the second lens and the third lens are all coated with an anti-reflection film, and the transmittance of the first lens, the second lens and the third lens is not less than 90%, and the surface tolerance is less than 20nm.

8. The laser beam expander according to claim 1, characterized in that: The length of the beam expander lens is not more than 30 mm, and the length of the laser beam expander is not more than 70 mm.

9. The laser beam expander according to claim 1, characterized in that: The outer periphery of the light emitting end is provided with a flange, the base body is provided with a connecting portion, the connecting portion is provided with a through hole and a fixing hole surrounding the through hole, at least a portion of the light emitting end is accommodated in the through hole, the flange stops on the connecting portion and is connected and fixed to the fixing hole through a fastener.

10. The laser beam expander according to claim 1, characterized in that: The base body is symmetrically provided with a first positioning protrusion and a second positioning protrusion on both sides along the length direction, the laser emitter is clamped and fixed between the first positioning protrusion and the second positioning protrusion, and the light outlet of the laser emitter faces the light inlet end of the first lens barrel.

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