Laser beam expanding method, beam expanding lens group, processing equipment and storage medium

Abstract

The invention provides a laser beam expanding method, a beam expanding lens group, processing equipment and a storage medium, and the method comprises the steps: rotating a first zero-order half-wave plate assembly, emitting random polarization laser, and dividing a light beam into 1 / 2 reflected light a and 1 / 2 transmitted light b; 1 / 2 reflected light a is reflected to a third zero-order half-wave plate assembly through a first thin film polaroid and a second reflector, so that the light beam is divided into 1 / 4 transmitted light e and 1 / 4 reflected light f; 1 / 4 transmission light e is transmitted out from the third film polaroid; 1 / 4 reflected light f is reflected out through a third thin film polaroid and a third reflector; 1 / 2 transmission light b penetrates through the first thin film polaroid and is emitted to a rotating second zero-order half-wave plate assembly, so that 1 / 4 transmission light c is split and is transmitted out from the second thin film polaroid, and 1 / 4 reflection light d is reflected out through the second thin film polaroid and the first reflector in sequence. Therefore, parallel beam expansion with a larger beam expansion ratio can be realized in a shorter optical path.

Description

Technical Field

[0001] The invention relates to laser beam expansion technology, and in particular to a method for expanding laser beams by using multiple polarizations, a beam expansion lens group, and processing equipment and storage media made thereof. Background Art

[0002] Laser beam expansion technology is mainly used to expand the diameter of a parallel input beam to a larger parallel output beam. This technology is developed from the basis of an optical telescope by adopting an afocal system design, so that the light from an object at infinity enters the optical axis of the internal optical component in a parallel manner, and also leaves in a parallel manner. The entire system has no focal length. Therefore, this technology is particularly suitable for occasions where the diameter and divergence angle of the laser beam need to be adjusted, such as laser scanning, interferometry or telemetry applications. Through the design of different beam expansion schemes, the laser system can be more flexibly adapted to various application requirements, thereby improving the performance and efficiency of the laser system.

[0003] At present, for lasers with a small divergence angle, that is, infinitely close to perfect collimation, the existing laser beam expansion methods are mainly divided into: transmission beam expansion, such as the Galilean telescope structure and the Kepler telescope structure; reflection beam expansion, such as off-axis reflection and prism multi-pass reflection structure; grating beam expansion, such as polymer beam splitting DOE.

[0004] However, all of the above-mentioned existing technical solutions have the problem of being unable to achieve a large beam expansion ratio within a short optical path, and the polymer beam splitting DOE solution also has the disadvantages of low diffraction efficiency and high-order diffraction, and the outgoing light beam will be deflected, and there is a problem of dispersing the incident light beam into multiple lasers in different directions. Summary of the invention

[0005] To this end, the main purpose of the present invention is to provide a laser beam expansion method, a beam expansion lens assembly and processing equipment, and a storage medium to achieve parallel beam expansion with a larger beam expansion ratio within a shorter optical path.

[0006] In order to achieve the above-mentioned object, according to one aspect of the present invention, a laser beam expander lens group is provided, which comprises: a first zero-order half-wave plate component, a first thin-film polarizer, a second zero-order half-wave plate component, a second thin-film polarizer, a first reflector, a third zero-order half-wave plate component, a second reflector, a third reflector, and a third thin-film polarizer, wherein the first zero-order half-wave plate component is perpendicular to the optical axis and rotates to split the light, the first thin-film polarizer is arranged on its splitting light path and is arranged at an angle of 45° to the incident light axis; the first and second thin-film polarizers are arranged in a mirror image; the second zero-order half-wave plate component is arranged at an angle of 45° to the incident light axis The axis is vertical, and it is arranged between the first and second thin-film polarizers to rotate and split the light; the first reflector is arranged on the reflected light path of the second thin-film polarizer, and the two are arranged in parallel; the second reflector is arranged on the reflected light path of the first thin-film polarizer, and the two are arranged in parallel; the third zero-order half-wave plate component is perpendicular to the incident light axis, and it is arranged on the reflected light path of the second reflector to rotate and split the light; the third thin-film polarizer is arranged on the splitting light path of the third zero-order half-wave plate component, and is arranged at a 45° angle to the incident light axis; the third reflector is arranged on the reflected light path of the third thin-film polarizer, and the two are arranged in parallel.

[0007] In a possible preferred embodiment, the third zero-order half-wave plate, the third reflector, and the third thin-film polarizer are arranged in a mirror-like parallelogram shape as are the second zero-order half-wave plate, the second thin-film polarizer, and the first reflector, so that the light beams reflected and transmitted respectively from the third reflector, the third thin-film polarizer, the second thin-film polarizer, and the first reflector are parallel and the light waists are tightly spliced.

[0008] In a possible preferred embodiment, the mirror size of the third zero-order half-wave plate is similar to that of the second zero-order half-wave plate; the mirror sizes of the first thin-film polarizer, the second thin-film polarizer, the first reflector, the second reflector, the third reflector, and the third thin-film polarizer are similar; the second reflector and the third thin-film polarizer are arranged in a right triangle with the third zero-order half-wave plate and the optical axis, respectively; the first thin-film polarizer and the second thin-film polarizer are arranged in a right triangle with the second zero-order half-wave plate and the optical axis, respectively.

[0009] In a possible preferred embodiment, the first, second and third zero-order half-wave plate assemblies respectively include: a zero-order half-wave plate and a rotating device, wherein the zero-order half-wave plate is connected to the rotating end of the rotating device, and driven by the rotating device, the zero-order half-wave plate rotates axially.

[0010] In a possible preferred embodiment, the beam expansion ratio of the laser beam expansion mirror assembly is 4.

[0011] In order to achieve the above object, according to another aspect of the present invention, a laser processing device is provided, which includes: a laser, a beam expansion system and a focusing system, wherein the beam expansion system adopts any of the laser beam expansion mirror groups described above.

[0012] In order to achieve the above object, according to another aspect of the present invention, a laser beam expansion method is also provided, the steps of which include:

[0013] The first zero-order half-wave plate assembly is rotated and a randomly polarized laser is injected into it to split the beam energy into two orthogonal linearly polarized beams: 1 / 2 reflected light a and 1 / 2 transmitted light b;

[0014] 1 / 2 reflected light a is sequentially reflected by the first thin film polarizer and the second reflector to the rotating third zero-order half-wave plate assembly, so as to split the light beam energy into two orthogonal linear polarized lights: 1 / 4 transmitted light e and 1 / 4 reflected light f;

[0015] 1 / 4 of the transmitted light e is transmitted from the third thin-film polarizer; 1 / 4 of the reflected light f is reflected from the third thin-film polarizer and the third reflector in sequence, and is parallel to the 1 / 4 of the transmitted light e, and the light waist is closely spliced;

[0016] 1 / 2 of the transmitted light b passes through the first thin film polarizer and is emitted to the rotating second zero-order half-wave plate assembly to split the light beam energy into two orthogonal linear polarized lights: 1 / 4 of the transmitted light c and 1 / 4 of the reflected light d;

[0017] 1 / 4 of the transmitted light c is transmitted through the second thin-film polarizer, and is parallel to the 1 / 4 of the transmitted light e, and the light waist is closely spliced; 1 / 4 of the reflected light d is reflected through the second thin-film polarizer and the first reflector in turn, and is parallel to the 1 / 4 of the transmitted light c, and the light waist is closely spliced.

[0018] In order to achieve the above-mentioned purpose, corresponding to the above-mentioned method, according to another aspect of the present invention, a computer-readable storage medium is also provided, wherein the computer-readable storage medium stores a computer program, wherein when the computer program is executed, the steps of the laser beam expansion method as described above are implemented.

[0019] The laser beam expansion method, beam expansion lens group, processing equipment and storage medium provided by the present invention cleverly utilize the optical properties of the zero-order half-wave plate, the thin-film polarizer and the reflector, and design the lens combination structure accordingly, so that a 4-fold beam expansion effect can be achieved within an extremely short optical path. At the same time, since the transmission beam expansion method is not adopted and all surface-type planar optical elements are adopted, the light beam is not affected by the lens surface and will not produce aberrations. After beam expansion, the light power density has high uniformity and will not change the divergence angle of the initial light spot. Therefore, after beam expansion, a good beam quality can be maintained. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 It is a schematic diagram of the structure of the laser beam expansion lens assembly of the present invention;

[0022] Figure 2 A schematic diagram of the reflection and transmission paths of a light beam in the laser beam expansion lens assembly of the present invention;

[0023] Figure 3 It is a schematic diagram of axial rotation and beam splitting of the first zero-order half-wave plate component in the laser beam expander assembly of the present invention;

[0024] Figure 4 Schematic diagram of the steps of the laser beam expansion method of the present invention.

[0025] Description of Reference Numerals

[0026] Laser 1, first zero-order half-wave plate assembly 2, first thin-film polarizer 3, second zero-order half-wave plate assembly 4, second thin-film polarizer 5, first reflector 6, third zero-order half-wave plate assembly 7, second reflector 8, third reflector 9, third thin-film polarizer 10, 1 / 2 reflected light a, 1 / 2 transmitted light b, 1 / 4 transmitted light e, 1 / 4 reflected light f, 1 / 4 transmitted light c, 1 / 4 reflected light d. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the technical solution of the present invention, the specific technical solution of the present invention will be clearly and completely described in conjunction with the embodiments below to help those skilled in the art further understand the present invention. Obviously, the embodiments described in this case are only embodiments of a part of the present invention, not all of the embodiments. It should be pointed out that for those of ordinary skill in the art, the embodiments in this application and the features in the embodiments can be combined with each other without departing from the concept of the present invention and without conflicting with each other. Based on the embodiments in the present invention, all other embodiments obtained without creative work by those of ordinary skill in the art should belong to the disclosure and protection scope of the present invention.

[0028] In addition, the terms "first", "second", etc. in the specification, claims and drawings of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the features used in this way can be interchanged where appropriate, so that the embodiments of the present invention described here can be implemented in an order other than those described here. At the same time, the stages recorded in each step are not mandatory to be implemented in the same step. It should be understood that the implementation order of the contents in each step stage can be adjusted and interchanged without violating the inventive concept, so that the step embodiments of the present invention described here can be implemented in an order other than those described here. In addition, the terms "including" and "having" and any of their variations in the present invention are intended to cover non-exclusive inclusions. Unless otherwise clearly specified and limited, the terms "set", "layout", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this case can be understood according to specific circumstances and in combination with the prior art.

[0029] To achieve parallel beam expansion with a larger beam expansion ratio in a shorter optical path, please refer to Figures 1 to 3 As shown, the present invention proposes a laser beam expander lens group, an example of which includes: a first zero-order half-wave plate component 2, a first thin-film polarizer 3, a second zero-order half-wave plate component 4, a second thin-film polarizer 5, a first reflector 6, a third zero-order half-wave plate component 7, a second reflector 8, a third reflector 9, and a third thin-film polarizer 10.

[0030] Among them, Figure 1 to Figure 2 As shown, the first zero-order half-wave plate component 2 is arranged perpendicular to the optical axis and rotates continuously to split the randomly polarized laser beam emitted by the laser 1 at 50:50, forming two beams of orthogonal linear polarized light: 1 / 2 reflected light a and 1 / 2 transmitted light b. The first thin-film polarizer 3 is arranged on the splitting light path of the first zero-order half-wave plate component 2 and is arranged at an angle of 45° to the incident light axis, so as to reflect 1 / 2 reflected light a at 90° through the first thin-film polarizer 3 and allow 1 / 2 transmitted light b to be transmitted therefrom.

[0031] Among them, the first and second thin-film polarizers 3 and 5 are arranged in mirror images and are perpendicular to each other. The second zero-order half-wave plate component 4 is perpendicular to the incident light axis. It is arranged between the first and second thin-film polarizers 3 and 5, and rotates continuously to split the 1 / 2 transmitted light b directed to the second zero-order half-wave plate component 4 into two orthogonal linear polarized lights: 1 / 4 transmitted light c and 1 / 4 reflected light d.

[0032] The first reflector 6 is arranged on the reflected light path of the second thin-film polarizer 5, and the two are arranged in parallel. At this time, the 1 / 4 transmitted light c is transmitted from the second thin-film polarizer 5 to form one beam expansion path, and the 1 / 4 reflected light d is reflected from the second thin-film polarizer 5 and the first reflector 6 in sequence to form another beam expansion path, and the 1 / 4 reflected light d and the 1 / 4 transmitted light c are parallel to each other and the light waists are closely spliced.

[0033] Among them, the second reflector 8 is arranged on the reflected light path of the first thin-film polarizer 3, and the two are arranged in parallel. The third zero-order half-wave plate component 7 is perpendicular to the incident light axis. It is arranged on the reflected light path of the second reflector 8 and continuously rotates the split light. At this time, 1 / 2 of the reflected light a reflected at 90° from the first thin-film polarizer 3 will be reflected by the second reflector 8 at 90° again to the third zero-order half-wave plate component 7, so as to split the light beam energy in half again into two beams of orthogonal linear polarized light: 1 / 4 transmitted light e, and 1 / 4 reflected light f.

[0034] The third thin-film polarizer 10 is arranged on the light splitting path of the third zero-order half-wave plate assembly 7 and is arranged at an angle of 45° to the incident light axis, and the third reflector 9 is arranged on the light reflecting path of the third thin-film polarizer 10, and the two are arranged in parallel. At this time, 1 / 4 of the transmitted light e is transmitted from the third thin-film polarizer 10 to form one beam expansion path, and 1 / 4 of the reflected light f is reflected from the third thin-film polarizer 10 and the third reflector 9 in sequence to form another beam expansion path, and the two beam expansion paths of 1 / 4 of the reflected light f and 1 / 4 of the transmitted light e are parallel and the light waists are closely spliced.

[0035] In this example, the first, second and third zero-order half-wave plate components 2, 4 and 7 respectively include: a zero-order half-wave plate and a rotating device, wherein the zero-order half-wave plate is connected to the rotating end of the rotating device and driven by the rotating device. Figure 3 As shown, the zero-order half-wave plate is axially rotatable. Since the rotatable zero-order half-wave plate component is an existing mature product, it will not be described in detail here.

[0036] In addition, in a preferred example, the third zero-order half-wave plate 7, the third reflector 9, the third thin-film polarizer 10, and the second zero-order half-wave plate 4, the second thin-film polarizer 5, and the first reflector 6 are arranged in a parallelogram-like shape that are mirror images of each other, so that the 1 / 4 transmitted light e and the 1 / 4 transmitted light c can be expanded in two ways and can be parallel and the light waists can be closely spliced, so that the light beams reflected and transmitted respectively from the third reflector 9, the third thin-film polarizer 10, the second thin-film polarizer 5, and the first reflector 6 can be parallel and the light waists can be closely spliced.

[0037] In addition, in order to ensure that the waists of the beams after beam expansion are equal, in a preferred example, the mirror size of the third zero-order half-wave plate 7 is similar to that of the second zero-order half-wave plate 4; the mirror sizes of the first thin-film polarizer 3, the second thin-film polarizer 5, the first reflector 6, the second reflector 8, the third reflector 9, and the third thin-film polarizer 10 are similar; the second reflector 8 and the third thin-film polarizer 10 are arranged in a right-angled triangle with the third zero-order half-wave plate 7 and the optical axis; the first thin-film polarizer 3 and the second thin-film polarizer 5 are arranged in a right-angled triangle with the second zero-order half-wave plate 4 and the optical axis. Thus, through this structural constraint, the waists of the beams after beam expansion of each path are equal.

[0038] With this setting, the laser beam expander group performs three-times polarization beam splitting, so that the initial laser can be expanded into four beams of equal power, equal light waist, and tightly spliced ​​at a shorter optical path, achieving a 4-fold beam expansion effect.

[0039] On the other hand, corresponding to the above-mentioned laser beam expanding mirror group example, the present invention also provides a laser processing equipment, which includes: a laser 1, a beam expanding system and a focusing system, wherein the beam expanding system adopts the laser beam expanding mirror group described in the above example.

[0040] On the other hand, corresponding to the above-mentioned laser beam expansion lens group example, Figure 4 As shown, the present invention also provides a laser beam expansion method, the steps of which include:

[0041] The first zero-order half-wave plate assembly 2 is rotated and a randomly polarized laser is injected thereto to split the beam energy in half into two orthogonal linearly polarized beams: 1 / 2 reflected light a and 1 / 2 transmitted light b.

[0042] 1 / 2 of the reflected light a is sequentially reflected by the first thin-film polarizer 3 and the second reflector 8 to the rotating third zero-order half-wave plate assembly 7, so as to split the light beam energy into two orthogonal linear polarized lights: 1 / 4 transmitted light e and 1 / 4 reflected light f.

[0043] 1 / 4 of the transmitted light e is transmitted from the third thin-film polarizer 10 ; 1 / 4 of the reflected light f is reflected from the third thin-film polarizer 10 and the third reflector 9 in sequence, and is parallel to the 1 / 4 of the transmitted light e and closely connected with the light waist.

[0044] 1 / 2 of the transmitted light b passes through the first thin-film polarizer 3 and is emitted to the rotating second zero-order half-wave plate assembly 4, so as to split the light beam energy into two orthogonal linear polarized lights: 1 / 4 of the transmitted light c and 1 / 4 of the reflected light d.

[0045] Among them, 1 / 4 of the transmitted light c is transmitted from the second thin film polarizer 5, and is parallel to 1 / 4 of the transmitted light e and the light waist is closely spliced; 1 / 4 of the reflected light d is reflected by the second thin film polarizer 5 and the first reflector 6 in turn, and is parallel to 1 / 4 of the transmitted light c and the light waist is closely spliced.

[0046] On the other hand, corresponding to the above-mentioned laser beam expansion method example, the present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, wherein when the computer program is executed, the steps of the laser beam expansion method as described above are implemented.

[0047] In summary, the laser beam expansion method, beam expansion lens group, processing equipment, and storage medium provided by the present invention cleverly utilize the optical properties of the zero-order half-wave plate, the thin-film polarizer, and the reflector, and design a corresponding lens combination structure, so that a 4-fold beam expansion effect can be achieved within an extremely short optical path. At the same time, since the transmission beam expansion method is not adopted and all surface-type planar optical elements are used, the light beam is not affected by the lens surface and will not produce aberrations. After beam expansion, the light power density has a high uniformity and will not change the divergence angle of the initial light spot. Therefore, after beam expansion, a good beam quality can be maintained.

[0048] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is only limited by the claims and their full scope and equivalents. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0049] Those skilled in the art can understand that, in addition to implementing the system, device, unit and its various modules provided by the present invention in a purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers and embedded microcontrollers by logically programming the method steps. Therefore, the system, device and its various modules provided by the present invention can be considered as a hardware component, and the modules included therein for implementing various programs can also be regarded as structures within the hardware component; the modules for implementing various functions can also be regarded as both software programs for implementing the method and structures within the hardware component.

[0050] In addition, all or part of the steps in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including a number of instructions to enable a single-chip microcomputer, a chip or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, RandomAccess Memory), disk or optical disk and other media that can store program codes.

[0051] In addition, various implementations of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed in the embodiments of the present invention.

Claims

1. A laser beam expander lens assembly, comprising: A first zero-order half-wave plate component, a first thin-film polarizer, a second zero-order half-wave plate component, a second thin-film polarizer, a first reflector, a third zero-order half-wave plate component, a second reflector, a third reflector, and a third thin-film polarizer, wherein the first zero-order half-wave plate component is perpendicular to the optical axis and rotates the light, the first thin-film polarizer is arranged on its light-splitting optical path and is arranged at a 45° angle to the incident optical axis; the first and second thin-film polarizers are arranged in a mirror image; the second zero-order half-wave plate component is perpendicular to the incident optical axis and is arranged between the first and second thin-film polarizers to rotate the light; the first reflector is arranged on the reflected light path of the second thin-film polarizer, and the two are arranged in parallel; the second reflector is arranged on the reflected light path of the first thin-film polarizer, and the two are arranged in parallel; the third zero-order half-wave plate component is perpendicular to the incident optical axis, and is arranged on the reflected light path of the second reflector to rotate the light; the third thin-film polarizer is arranged on the light-splitting optical path of the third zero-order half-wave plate component and is arranged at a 45° angle to the incident optical axis; the third reflector is arranged on the reflected light path of the third thin-film polarizer, and the two are arranged in parallel.

2. The laser beam expander lens assembly according to claim 1, wherein the third zero-order half-wave plate, the third reflector, and the third thin-film polarizer, as well as the second zero-order half-wave plate, the second thin-film polarizer, and the first reflector are arranged in a parallelogram-like shape that are mirror images of each other, so that the light beams reflected and transmitted respectively from the third reflector, the third thin-film polarizer, the second thin-film polarizer, and the first reflector are parallel and the light waists are closely spliced.

3. The laser beam expander lens assembly according to claim 2, wherein the mirror size of the third zero-order half-wave plate is similar to that of the second zero-order half-wave plate; the mirror sizes of the first thin-film polarizer, the second thin-film polarizer, the first reflector, the second reflector, the third reflector, and the third thin-film polarizer are similar; the second reflector and the third thin-film polarizer are arranged in a right-angled triangle with the third zero-order half-wave plate and the optical axis, respectively; the first thin-film polarizer and the second thin-film polarizer are arranged in a right-angled triangle with the second zero-order half-wave plate and the optical axis, respectively.

4. The laser beam expander assembly according to any one of claims 1 to 3, wherein the first, second and third zero-order half-wave plate components respectively comprise: A zero-order half-wave plate and a rotating device, wherein the zero-order half-wave plate is connected to the rotating end of the rotating device and driven by the rotating device to rotate axially. The laser beam expander assembly according to claim 1 , wherein the beam expansion ratio of the laser beam expander assembly is 4.

6. A laser processing device, comprising: A laser, a beam expansion system and a focusing system, wherein the beam expansion system adopts the laser beam expansion mirror assembly as described in any one of claims 1 to 5.

7. A laser beam expansion method, comprising the steps of: The first zero-order half-wave plate assembly is rotated and a randomly polarized laser is injected into it to split the beam energy into two orthogonal linearly polarized beams: 1 / 2 reflected light a and 1 / 2 transmitted light b; 1 / 2 reflected light a is sequentially reflected by the first thin film polarizer and the second reflector to the rotating third zero-order half-wave plate assembly, so as to split the light beam energy into two orthogonal linear polarized lights: 1 / 4 transmitted light e and 1 / 4 reflected light f; 1 / 4 of the transmitted light e is transmitted from the third thin-film polarizer; 1 / 4 of the reflected light f is reflected from the third thin-film polarizer and the third reflector in sequence, and is parallel to the 1 / 4 of the transmitted light e, and the light waist is closely spliced; 1 / 2 of the transmitted light b passes through the first thin film polarizer and is emitted to the rotating second zero-order half-wave plate assembly to split the light beam energy into two orthogonal linear polarized lights: 1 / 4 of the transmitted light c and 1 / 4 of the reflected light d; 1 / 4 of the transmitted light c is transmitted through the second thin-film polarizer, and is parallel to the 1 / 4 of the transmitted light e, and the light waist is closely spliced; 1 / 4 of the reflected light d is reflected through the second thin-film polarizer and the first reflector in turn, and is parallel to the 1 / 4 of the transmitted light c, and the light waist is closely spliced.

8. A computer-readable storage medium storing a computer program, wherein when the computer program is executed, the steps of the laser beam expansion method according to claim 7 are implemented.

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