Laser beam expander unit with secondary mirror focusing function and focusing mechanism debugging method

Abstract

The laser beam expander unit with secondary mirror focusing function and the focusing mechanism debugging method belong to the technical field of laser beam expansion, and aim to solve the problems that the existing technology has the non-parallel guide rail mounting surface, it is difficult to ensure the precision during the installation of the mechanism, frequent detection and adjustment are needed, and the conventional measuring tools cannot realize accurate measurement. The present application comprises: a secondary mirror unit, an intermediate force bearing cylinder and a primary mirror unit which are coaxially arranged from top to bottom; an axial motion driving mechanism connected between the outer surface of the primary force bearing cylinder of the primary mirror unit and the outer surface of the intermediate force bearing cylinder, which drives the secondary mirror unit and the intermediate force bearing cylinder to make axial motion relative to the primary mirror unit; a plurality of groups of sliding guide and limiting structures which are circumferentially distributed on the outer surface of the connection part of the primary force bearing cylinder and the intermediate force bearing cylinder of the primary mirror unit; and a focusing mechanism installation and debugging device which adjusts the parallelism between the sliding guide rails in the plurality of groups of sliding guide and limiting structures and the motion direction.

Description

Technical Field

[0001] This invention belongs to the field of laser beam expansion technology, specifically relating to a laser beam expansion unit with secondary mirror focusing function and a focusing mechanism debugging method. Background Technology

[0002] A laser beam expander can enlarge the diameter of a collimated input beam to obtain a larger diameter collimated output beam, commonly used in applications such as laser scanning, interferometry, or telemetry. During use, the collimated output beam needs to be focused, thus requiring a focusing function. Furthermore, during ground assembly and transportation, factors such as temperature, pressure, and vibration can cause the system to defocus, necessitating a focusing mechanism to compensate for the defocusing. Due to the small size and light weight of the secondary mirror, a focusing method using the secondary mirror is often employed for system focusing.

[0003] Common secondary mirror focusing methods include thermal focusing and mechanical focusing. Thermal focusing suffers from inadequate heat dissipation and insulation, leading to thermal deformation of the optomechanical structure and ultimately affecting image quality. Mechanical focusing schemes include cam drives and lead screw-nut drives. Cam drives offer advantages such as simple structure, high precision, and high load-bearing capacity, but they are bulky and difficult to manufacture. Lead screw-nut drives offer advantages such as compact structure, smooth transmission, high precision, and ease of manufacturing. Therefore, current research often uses lead screw-nut drives as the secondary mirror focusing mechanism. However, for secondary mirror focusing mechanisms with multi-point support, the following problems exist: the guide rail mounting surfaces are not parallel, requiring multiple guide rails to be simultaneously parallel and perpendicular to the load-bearing cylinder's reference plane, making it difficult to guarantee accuracy during installation; frequent inspection and adjustment are required during installation, and conventional gauges cannot achieve accurate measurements; assembly using a coordinate measuring machine is extremely time-consuming and cumbersome. Summary of the Invention

[0004] The purpose of this invention is to propose a laser beam expander unit with secondary mirror focusing function and a focusing mechanism debugging method, which solves the problems of non-parallel guide rail mounting surfaces, difficulty in ensuring accuracy during installation, the need for frequent testing and adjustment, and the inability of conventional gauges to achieve accurate measurement in the existing technology.

[0005] To achieve the above objectives, the laser beam expander unit with secondary mirror focusing function of the present invention includes:

[0006] The secondary mirror unit, the intermediate support cylinder, and the primary mirror unit are arranged coaxially from top to bottom.

[0007] An axial motion drive mechanism is connected between the outer surface of the main support cylinder and the outer surface of the intermediate support cylinder of the primary mirror unit. The axial motion drive mechanism drives the secondary mirror unit and the intermediate support cylinder to move axially relative to the primary mirror unit.

[0008] Multiple sets of sliding guide and limiting structures are evenly distributed on the outer surface of the connection between the main support cylinder and the intermediate support cylinder of the primary mirror unit. These sliding guide and limiting structures guide the movement of the secondary mirror unit and the intermediate support cylinder relative to the primary mirror unit and limit their vertical displacement.

[0009] And a focusing mechanism installation and debugging equipment, which is used to adjust the sliding guide rails in multiple sets of sliding guides and limiting structures to be parallel to the direction of movement.

[0010] The axial motion drive mechanism includes:

[0011] A stepper motor is fixed to the outer surface of the main load-bearing cylinder of the main mirror unit via a motor mount;

[0012] A lead screw shaft integrally mounted on the output shaft of a stepper motor;

[0013] A first nut is threadedly connected to the lead screw shaft, and the first nut is fixedly connected to the intermediate bearing cylinder through a first nut seat;

[0014] A second nut is threadedly connected to the lead screw shaft, and the second nut is fixedly connected to the intermediate bearing cylinder through a second nut seat;

[0015] And a compression spring fitted onto the lead screw shaft and located between the first nut and the second nut.

[0016] Each set of sliding guide and limiting structures includes:

[0017] The sliding guide rail is fixed to the boss on the outer cylindrical surface of the main load-bearing cylinder by screws;

[0018] A slider that slides in conjunction with the sliding guide rail;

[0019] The guide rail bearing plate has a U-shaped structure. The mounting surface of the guide rail bearing plate is fixedly connected by screws and sliders. One bearing surface is connected to the lower middle connecting lug of the middle bearing cylinder by screws. When the guide rail bearing plate moves to the two extreme positions relative to the sliding guide rail, the two opposite inner surfaces of the guide rail bearing plate respectively contact and limit the movement with the two end faces of the sliding guide rail.

[0020] The installation and commissioning equipment includes:

[0021] Marble countertop;

[0022] A mounting base set on a marble table, the mounting base including a bottom base and a support column, the support column having a protrusion on its side;

[0023] Linear guide rails are mounted on the bosses on the side of the support columns of the mounting base.

[0024] A guide rail slider that slides vertically in cooperation with the linear guide rail;

[0025] The dial indicator bracket is fixedly connected to the guide rail slider;

[0026] And a dial indicator mounted on a dial indicator bracket.

[0027] The laser beam expanding unit also includes:

[0028] Multiple support hinges are evenly distributed around the circumference. Each support hinge includes an upper connecting plate fixedly connected to the main load-bearing mounting flange of the main load-bearing cylinder, a lower connecting plate arranged parallel to the upper connecting plate, and an intermediate support plate connected between the upper connecting plate and the lower connecting plate. The intermediate support plate is provided with a straight groove.

[0029] The self-resetting potentiometer is fixed to the boss on the outer cylindrical surface of the main bearing cylinder by screws and is connected to the middle lower connecting lug of the intermediate bearing cylinder.

[0030] And an optical axis adjustment structure, the optical axis adjustment structure including a prism mounted on a boss on the outer cylindrical surface of the main bearing cylinder via a prism mounting seat, the normal of the prism being parallel to the optical axis of the main mirror unit.

[0031] The secondary mirror unit includes:

[0032] The secondary mirror support tube includes a hollow secondary mirror body, a secondary mirror support platform coaxially disposed within the secondary mirror body, three secondary mirror support plates connected between the secondary mirror body and the secondary mirror support platform and evenly distributed around the circumference, and three secondary mirror lower connecting ears evenly distributed around the circumference on the outer surface of the secondary mirror body near one end of the middle support tube.

[0033] And a secondary mirror that is coaxially connected to the secondary mirror bearing cylinder via a secondary mirror adapter hinge.

[0034] The secondary mirror adapter hinge includes:

[0035] The upper surface of the secondary mirror is bonded to the lower surface of the intermediate cylindrical boss of the secondary mirror transition hinge by optical epoxy adhesive.

[0036] A circular ring coaxially positioned outside the central cylindrical boss;

[0037] Multiple flexible hinges are connected between the central cylindrical boss and the ring and are evenly distributed around the circumference. The flexible hinges are machined with grooves for adjustment.

[0038] And three threaded bosses evenly distributed on the circumference of the ring, the three threaded bosses being connected to the secondary mirror support platform of the secondary mirror support cylinder by screws.

[0039] The intermediate support cylinder is a hollow cylinder with multiple reinforcing ribs evenly distributed around its outer surface. Three upper intermediate connecting ears are evenly distributed around the outer surface of the intermediate cylinder near the secondary mirror unit, and five lower intermediate connecting ears are evenly distributed around the outer surface of the intermediate cylinder near the primary mirror unit. The three lower secondary mirror connecting ears of the secondary mirror support cylinder correspond one-to-one with the three upper intermediate connecting ears of the intermediate support cylinder and are connected by screws. An adjustment shim is provided between each lower secondary mirror connecting ear and each upper intermediate connecting ear.

[0040] The primary mirror unit includes:

[0041] The main load-bearing cylinder is a hollow cylindrical body with three annular ribs arranged axially inside. The outer surface of the main load-bearing cylinder is provided with a main load-bearing mounting boss for installation. The lower end of the main load-bearing cylinder is provided with a main load-bearing mounting flange.

[0042] The first and second primary mirrors are coaxially arranged with the main load-bearing cylinder. The lower surface of the first primary mirror and the upper surface of the second primary mirror are bonded together with optical epoxy adhesive. The outer cylindrical surface of the second primary mirror is connected to the main load-bearing mounting flange of the main load-bearing cylinder through a primary mirror adapter hinge.

[0043] The primary mirror adapter hinge includes:

[0044] The annular body has its inner ring surface and the outer cylindrical surface of the second primary mirror bonded together with optical epoxy adhesive. The annular body has evenly distributed arc-shaped grooves around its circumference.

[0045] And three L-shaped connecting ears evenly distributed on the outer surface of the annular body; the three L-shaped connecting ears are connected by screws and the main load-bearing mounting flange of the main load-bearing cylinder; a straight groove is machined on one end of the L-shaped connecting ear and the annular body, and the arc groove on the annular body and the straight groove on the L-shaped connecting ear serve as flexible links.

[0046] The debugging method for the focusing mechanism of the laser beam expander unit with secondary mirror focusing function is as follows: Grind the bottom surface of the mounting base and the mounting surface of the linear guide rail to make the bottom surface of the mounting base perpendicular to the mounting surface of the linear guide rail; install the linear guide rail and dial indicator, making the movement direction of the dial indicator perpendicular to the reference surface of the bottom surface of the mounting base; fix the mounting base on the marble platform; mount the laser beam expander unit on the marble platform through a support hinge; move the dial indicator up and down to measure the reference surfaces of the three sliding guide rails, and repeatedly adjust the position of the sliding guide rails according to the measured reference surfaces of the three sliding guide rails so that the three sliding guide rails are parallel to the movement direction of the secondary mirror unit and the intermediate support cylinder; after adjustment, record the data, and use a coordinate measuring machine for final data inspection to complete the debugging.

[0047] The beneficial effects of this invention are as follows: When secondary mirror focusing of the laser beam expander unit and focusing mechanism of this invention are required, a pulse signal is given to the stepper motor, causing the motor lead screw to rotate and drive the first nut and the second nut to move linearly. Simultaneously, due to the preload of the spring between the first and second nuts, the gap between the lead screw and the nut is eliminated, improving transmission accuracy. The secondary mirror, secondary mirror support cylinder, and intermediate support cylinder components move up and down along the guide rails evenly distributed on the outer side of the main support cylinder under the thrust of the nut, realizing the secondary mirror focusing function. The secondary mirror focusing is performed using a motor-driven, lead screw and nut transmission method, and the double-nut plus spring structure eliminates the gap between the lead screw and nut, offering advantages such as simple structure, high precision, and high reliability. Before focusing, the focusing mechanism is adjusted by installing and debugging equipment to ensure the parallelism of the three sliding guide rails. A testing device based on a dial indicator is built, offering advantages such as simple testing equipment, high installation and debugging efficiency, and high testing accuracy. Compared to conventional laser beam expanders, this invention adds a secondary mirror focusing function, allowing for focal length adjustment according to usage requirements, offering the advantage of flexible adjustment. The invention employs a motor-driven, lead screw and nut-driven focusing mechanism, which boasts advantages of simple structure and high precision. This invention uses three evenly arranged guide rail slider assemblies to focus the load-bearing cylinder, resulting in uniform and stable stress distribution and high reliability. This invention designs three flexible adjustment links: a secondary mirror adapter hinge, a primary mirror adapter hinge, and a support hinge, which reduces the impact of external factors such as installation and thermal deformation on the laser beam expander. Compared to other installation and debugging methods, the focusing mechanism installation and debugging method of this invention offers advantages such as simple testing equipment, high installation and debugging efficiency, and high testing accuracy. Attached Figure Description

[0048] Figure 1 This is an external view of the laser beam expander unit with secondary mirror focusing function of the present invention.

[0049] Figure 2 This is a cross-sectional view of the laser beam expander unit with secondary mirror focusing function of the present invention.

[0050] Figure 3 This is an enlarged view of the axial motion drive mechanism in the laser beam expander unit with secondary mirror focusing function of the present invention.

[0051] Figure 4 This is a bottom view of the laser beam expander unit with secondary mirror focusing function of the present invention;

[0052] Figure 5 This is a structural diagram of the secondary mirror transition hinge in the laser beam expander unit with secondary mirror focusing function of the present invention.

[0053] Figure 6 This is a structural diagram of the primary mirror transition hinge in the laser beam expander unit with secondary mirror focusing function of the present invention.

[0054] Figure 7 This is a schematic diagram illustrating the installation and debugging of the focusing mechanism in the laser beam expander unit with secondary mirror focusing function of the present invention.

[0055] The components include: 1. Secondary mirror unit, 101. Secondary mirror support cylinder, 102. Secondary mirror lower connecting lug, 103. Secondary mirror transition hinge, 104. Secondary mirror, 105. Intermediate cylindrical boss, 106. Ring, 107. Flexible hinge, 108. Boss with threaded hole; 2. Intermediate support cylinder, 201. Intermediate upper connecting lug, 202. Intermediate lower connecting lug; 3. Primary mirror unit, 301. Primary support cylinder, 302. Primary support mounting flange, 303. First primary mirror, 304. Second primary mirror, 305. Primary mirror transition hinge, 306. Annular body, 307. L-shaped connecting lug, 308. Flexible link; 4. Axial motion drive mechanism. 401. Motor mount; 402. Stepper motor; 403. First nut; 404. First nut seat; 405. Second nut; 406. Second nut seat; 407. Compression spring; 5. Sliding guide and limiting structure; 501. Sliding guide rail; 502. Slider; 503. Guide rail support plate; 6. Installation and debugging equipment; 601. Marble table; 602. Mounting base; 603. Linear guide rail; 604. Guide rail slider; 605. Dial indicator bracket; 606. Dial indicator; 7. Adjusting shim; 8. Support hinge; 9. Self-resetting potentiometer; 10. Optical axis adjustment structure; 1001. Prism; 1002. Prism mounting base. Detailed Implementation

[0056] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0057] See Figures 1-7 The laser beam expander unit with secondary mirror focusing function of the present invention includes:

[0058] The secondary mirror unit 1, the intermediate load-bearing cylinder 2, and the primary mirror unit 3 are arranged coaxially from top to bottom.

[0059] An axial motion drive mechanism 4 is connected between the outer surface of the main support cylinder 301 and the outer surface of the intermediate support cylinder 2 of the main mirror unit 3. The axial motion drive mechanism 4 drives the secondary mirror unit 1 and the intermediate support cylinder 2 to move axially relative to the main mirror unit 3.

[0060] Multiple sets of sliding guide and limiting structures 5 are evenly distributed on the outer surface of the connection between the main support cylinder 301 and the intermediate support cylinder 2 of the main mirror unit 3. The sliding guide and limiting structures 5 guide the movement of the secondary mirror unit 1 and the intermediate support cylinder 2 relative to the main mirror unit 3 and limit the vertical displacement.

[0061] And the focusing mechanism installation and debugging equipment 6, through which the sliding guide rails 501 in the multiple sets of sliding guide and limiting structures 5 are adjusted to be parallel to the direction of movement.

[0062] The axial motion drive mechanism 4 includes:

[0063] A stepper motor 402 is fixed to the outer surface of the main load-bearing cylinder 301 of the main mirror unit 3 via a motor mount 401;

[0064] A lead screw shaft is integrally mounted on the output shaft of stepper motor 402;

[0065] A first nut 403 is threadedly connected to the lead screw shaft. The first nut 403 is fixedly connected to the intermediate bearing cylinder 2 via a first nut seat 404. The first nut seat 404 is fixedly connected to the intermediate bearing cylinder 2 via screws.

[0066] The second nut 405 is threadedly connected to the lead screw shaft. The second nut 405 is fixedly connected to the intermediate support cylinder 2 via the second nut seat 406. The second nut seat 406 is fixedly connected to the intermediate support cylinder 2 via screws. By rotating the screws, the distance between the first nut seat 404 and the second nut seat 406 is adjusted, the compression amount of the compression spring 407 is adjusted, and thus the tightness of the fit between the first nut 403 and the second nut 405 and the lead screw is adjusted.

[0067] And a compression spring 407, which is sleeved on the lead screw shaft and located between the first nut 403 and the second nut 405, is used to eliminate the gap between the first nut 403, the second nut 405 and the lead screw.

[0068] Each set of sliding guide and limiting structures 5 includes:

[0069] The sliding guide rail 501 is fixed to the boss on the outer cylindrical surface of the main bearing cylinder 301 by screws;

[0070] Slider 502 that slides in cooperation with the sliding guide rail 501;

[0071] And a U-shaped guide rail support plate 503, the mounting surface of the guide rail support plate 503 is fixedly connected to the slider 502 by screws, and one support surface is connected to the middle lower connecting ear 202 of the middle support cylinder 2 by screws. When the guide rail support plate 503 moves to the two extreme positions relative to the sliding guide rail 501, the two opposite inner surfaces of the guide rail support plate 503 respectively contact and limit the two end faces of the sliding guide rail 501.

[0072] The installation and commissioning equipment 6 includes:

[0073] Marble countertop 601;

[0074] A mounting base 602 is provided on a marble table 601. The mounting base 602 includes a bottom base and a support column. The support column has a protrusion on its side.

[0075] Linear guide rail 603 is installed on the boss on the side of the support column of the mounting base 602;

[0076] A guide rail slider 604 that slides vertically in cooperation with the linear guide rail 603;

[0077] The dial indicator bracket 605 is fixedly connected to the guide rail slider 604;

[0078] And a dial indicator 606 mounted on a dial indicator bracket 605.

[0079] The laser beam expanding unit also includes:

[0080] Multiple support hinges 8 are evenly distributed around the circumference. Each support hinge 8 includes an upper connecting plate fixedly connected to the main load-bearing mounting flange 302 of the main load-bearing cylinder 301, a lower connecting plate arranged parallel to the upper connecting plate, and an intermediate support plate connected between the upper and lower connecting plates. The intermediate support plate is provided with a straight groove. The support hinge 8 has the functions of transition and flexible adjustment, wherein the flexible support plate can reduce the impact of installation unevenness and thermal deformation.

[0081] The self-resetting potentiometer 9 is fixed to the boss on the outer cylindrical surface of the main bearing cylinder 301 by screws and is connected to the middle lower connecting lug 202 of the intermediate bearing cylinder 2.

[0082] And an optical axis adjustment structure 10, the optical axis adjustment structure 10 including a prism 1001 mounted on a boss on the outer cylindrical surface of the main support cylinder 301 via a prism mounting base 1002, the normal of the prism 1001 being parallel to the optical axis of the main mirror unit 3. The prism 1001 is used to adjust the optical axis.

[0083] The secondary mirror unit 1 includes:

[0084] Secondary mirror support cylinder 101 includes a hollow secondary mirror 104 cylinder, a secondary mirror 104 support platform coaxially disposed inside the secondary mirror 104 cylinder, three secondary mirror 104 support plates connected between the secondary mirror 104 cylinder and the secondary mirror 104 support platform and evenly distributed around the circumference, and three secondary mirror lower connecting lugs 102 evenly distributed around the circumference of the outer surface of the secondary mirror 104 cylinder near one end of the intermediate support cylinder 2.

[0085] And a secondary mirror 104 coaxially connected to the secondary mirror support cylinder 101 via a secondary mirror adapter hinge 103.

[0086] The secondary mirror adapter hinge 103 includes:

[0087] The middle cylindrical boss 105 is located in the middle, and the upper surface of the secondary mirror 104 is bonded to the lower surface of the middle cylindrical boss 105 of the secondary mirror transition hinge 103 by optical epoxy adhesive.

[0088] A ring 106 is coaxially disposed on the outside of the central cylindrical boss 105;

[0089] Multiple flexible hinges 107 are evenly distributed around the circumference between the central cylindrical boss 105 and the ring 106. The flexible hinges 107 are machined with grooves for adjustment. The central cylindrical boss 105 can be freely adjusted under the action of the flexible hinges 107.

[0090] And three bosses 108 with threaded holes are evenly distributed on the circumference of the ring 106. The three bosses 108 with threaded holes are connected to the secondary mirror 104 support platform of the secondary mirror support cylinder 101 by screws.

[0091] The intermediate support cylinder 2 is a hollow intermediate cylinder with multiple reinforcing ribs evenly distributed around its outer surface. Three upper intermediate connecting ears 201 are evenly distributed around the outer surface of the intermediate cylinder near the secondary mirror unit 1, and five lower intermediate connecting ears 202 are evenly distributed around the outer surface of the intermediate cylinder near the primary mirror unit 3. The three lower secondary mirror connecting ears 102 of the secondary mirror support cylinder 101 correspond one-to-one with the three upper intermediate connecting ears 201 of the intermediate support cylinder 2 and are connected by screws. An adjustment shim 7 is provided between each lower secondary mirror connecting ear 102 and the upper intermediate connecting ear 201.

[0092] The primary mirror unit 3 includes:

[0093] The main load-bearing cylinder 301 is a hollow main load-bearing cylindrical body. Three annular ribs are arranged axially inside the main load-bearing cylindrical body. The outer surface of the main load-bearing cylindrical body is provided with a main load-bearing mounting boss for installation. The lower end of the main load-bearing cylindrical body is provided with a main load-bearing mounting flange 302.

[0094] The first primary mirror 303 and the second primary mirror 304 are coaxially arranged with the main load-bearing cylinder 301. The lower surface of the first primary mirror 303 and the upper surface of the second primary mirror 304 are bonded together with optical epoxy adhesive. The outer cylindrical surface of the second primary mirror 304 is connected to the main load-bearing mounting flange 302 of the main load-bearing cylinder 301 through the primary mirror adapter hinge 305.

[0095] The primary mirror adapter hinge 305 includes:

[0096] The annular body 306 has its inner annular surface and the outer cylindrical surface of the second primary mirror 304 bonded together with optical epoxy adhesive. The annular body 306 has evenly distributed arc-shaped grooves around its circumference.

[0097] And three L-shaped connecting ears 307 evenly distributed on the outer surface of the annular body 306; the three L-shaped connecting ears 307 are connected by screws and the main load-bearing mounting flange 302 of the main load-bearing cylinder 301; a straight groove is machined on one end of the L-shaped connecting ear 307 and the annular body 306, and the arc groove on the annular body 306 and the straight groove on the L-shaped connecting ear 307 serve as flexible links 308.

[0098] The primary mirror adapter hinge 305 has the functions of installing the primary mirror, adapter, and flexible adjustment. The flexible link 308 can reduce the impact of external factors such as installation and thermal deformation on the primary mirror.

[0099] The straight grooves and arc grooves mentioned in this embodiment are preferably formed by wire electrical discharge machining.

[0100] The debugging method for the focusing mechanism of the laser beam expander unit with secondary mirror focusing function is as follows: Grind the bottom surface of the mounting base 602 and the mounting surface of the linear guide rail 603 so that the bottom surface of the mounting base 602 is perpendicular to the mounting surface of the linear guide rail 603; install the linear guide rail 603 and the dial indicator 606 so that the movement direction of the dial indicator 606 is perpendicular to the reference plane of the bottom surface of the mounting base 602; fix the mounting base 602 on the marble table 601; the laser beam expander unit is installed on the marble table 601 through the support hinge 8; move the dial indicator 606 up and down to measure the reference plane of the three sliding guide rails 501, and repeatedly adjust the position of the sliding guide rails 501 according to the measured reference plane of the three sliding guide rails 501 so that the movement direction of the three sliding guide rails 501 is parallel to that of the secondary mirror unit 1 and the intermediate support cylinder 2; after the adjustment is completed, record the data, and use a coordinate measuring machine to perform final data inspection to complete the debugging.

Claims

1. A laser beam expander unit with secondary mirror focusing function, characterized in that, include: The secondary mirror unit (1), the intermediate support cylinder (2), and the primary mirror unit (3) are arranged coaxially from top to bottom. An axial motion drive mechanism (4) is connected between the outer surface of the main support cylinder (301) and the outer surface of the intermediate support cylinder (2) of the main mirror unit (3). The axial motion drive mechanism (4) drives the secondary mirror unit (1) and the intermediate support cylinder (2) to move axially relative to the main mirror unit (3). Multiple sets of sliding guide and limiting structures (5) are evenly distributed on the outer surface of the connection between the main support cylinder (301) and the intermediate support cylinder (2) of the main mirror unit (3). The sliding guide and limiting structures (5) guide the movement of the secondary mirror unit (1) and the intermediate support cylinder (2) relative to the main mirror unit (3) and limit the vertical displacement. And the focusing mechanism installation and debugging equipment (6), through the focusing mechanism installation and debugging equipment (6), adjust the sliding guide rail (501) in the multiple sets of sliding guide and limiting structures (5) to be parallel to the direction of movement; The installation and commissioning equipment (6) includes: Marble countertop (601); A mounting base (602) is provided on a marble table (601), the mounting base (602) includes a bottom base and a support column, and the support column has a protrusion on its side; Linear guide rail (603) is installed on the boss on the side of the support column of the mounting base (602). A guide rail slider (604) that slides vertically in cooperation with the linear guide rail (603). The dial indicator bracket (605) is fixedly connected to the guide rail slider (604). And a dial indicator (606) mounted on a dial indicator bracket (605).

2. The laser beam expander unit with secondary mirror focusing function according to claim 1, characterized in that, The axial motion drive mechanism (4) includes: A stepper motor (402) is fixed to the outer surface of the main support cylinder (301) of the main mirror unit (3) via a motor mount (401). A lead screw shaft is integrally mounted on the output shaft of the stepper motor (402); The first nut (403) is threadedly connected to the lead screw shaft, and the first nut (403) is fixedly connected to the intermediate bearing cylinder (2) through the first nut seat (404); The second nut (405) is threadedly connected to the lead screw shaft, and the second nut (405) is fixedly connected to the intermediate bearing cylinder (2) through the second nut seat (406); And a compression spring (407) fitted on the lead screw shaft and located between the first nut (403) and the second nut (405).

3. The laser beam expander unit with secondary mirror focusing function according to claim 1, characterized in that, Each set of sliding guide and limiting structures (5) includes: The sliding guide rail (501) is fixed to the boss on the outer cylindrical surface of the main bearing cylinder (301) by screws. A slider (502) that slides in cooperation with the sliding guide rail (501); And a U-shaped guide rail support plate (503), the mounting surface of the guide rail support plate (503) is fixedly connected by screws and slider (502), and one support surface is connected by screws and the middle lower connecting ear (202) of the middle support cylinder (2). When the guide rail support plate (503) moves to the two extreme positions relative to the sliding guide rail (501), the two opposite inner surfaces of the guide rail support plate (503) respectively contact and limit the two end faces of the sliding guide rail (501).

4. The laser beam expander unit with secondary mirror focusing function according to any one of claims 1-3, characterized in that, The laser beam expanding unit also includes: Multiple support hinges (8) are evenly distributed around the circumference. Each support hinge (8) includes an upper connecting plate fixedly connected to the main load-bearing mounting flange (302) of the main load-bearing cylinder (301), a lower connecting plate arranged parallel to the upper connecting plate, and an intermediate support plate connected between the upper connecting plate and the lower connecting plate. The intermediate support plate is provided with a straight groove. The self-resetting potentiometer (9) is fixed to the boss on the outer cylindrical surface of the main bearing cylinder (301) by screws and is connected to the middle lower connecting ear (202) of the intermediate bearing cylinder (2). And an optical axis adjustment structure (10), the optical axis adjustment structure (10) includes a prism (1001) mounted on a boss on the outer cylindrical surface of the main bearing cylinder (301) via a prism mounting base (1002), the normal of the prism (1001) being parallel to the optical axis of the main mirror unit (3).

5. The laser beam expander unit with secondary mirror focusing function according to claim 1, characterized in that, The secondary mirror unit (1) includes: Secondary mirror support cylinder (101), the secondary mirror support cylinder (101) includes a hollow secondary mirror (104) cylinder, a secondary mirror (104) support platform coaxially arranged in the secondary mirror (104) cylinder, three secondary mirror (104) support plates evenly distributed circumferentially between the secondary mirror (104) cylinder and the secondary mirror (104) support platform, and three secondary mirror (104) lower connecting ears (102) evenly distributed circumferentially on the outer surface of the secondary mirror (104) cylinder near one end of the middle support cylinder (2). And a secondary mirror (104) coaxially connected to the secondary mirror support cylinder (101) via a secondary mirror adapter hinge (103). The secondary mirror adapter hinge (103) includes: The upper surface of the secondary mirror (104) is bonded to the lower surface of the middle cylindrical boss (105) of the secondary mirror transition hinge (103) by optical epoxy adhesive. A ring (106) is coaxially arranged on the outside of the central cylindrical boss (105). Multiple flexible hinges (107) are connected between the central cylindrical boss (105) and the ring (106) and are evenly distributed around the circumference. The flexible hinges (107) are machined with grooves for adjustment. And three threaded bosses (108) evenly distributed on the circumference of the ring (106), the three threaded bosses (108) are connected to the secondary mirror (104) support platform of the secondary mirror support cylinder (101) by screws.

6. The laser beam expander unit with secondary mirror focusing function according to claim 5, characterized in that, The intermediate support cylinder (2) is a hollow intermediate cylinder with multiple reinforcing ribs evenly distributed on its outer surface. Three intermediate upper connecting ears (201) are evenly distributed on the outer surface of the intermediate cylinder near the secondary mirror unit (1), and five intermediate lower connecting ears (202) are evenly distributed on the outer surface of the intermediate cylinder near the primary mirror unit (3). The three secondary lower connecting ears (102) of the secondary mirror support cylinder (101) correspond one-to-one with the three intermediate upper connecting ears (201) of the intermediate support cylinder (2) and are connected by screws. An adjustment shim (7) is provided between each secondary lower connecting ear (102) and the intermediate upper connecting ear (201).

7. The laser beam expander unit with secondary mirror focusing function according to claim 1, characterized in that, The primary mirror unit (3) includes: The main load-bearing cylinder (301) is a hollow main load-bearing cylindrical body. Three annular ribs are arranged axially inside the main load-bearing cylindrical body. The outer surface of the main load-bearing cylindrical body is provided with a main load-bearing mounting boss for installation. A main load-bearing mounting flange (302) is provided at the lower end of the main load-bearing cylindrical body. The first primary mirror (303) and the second primary mirror (304) are coaxially arranged with the main load-bearing cylinder (301). The lower surface of the first primary mirror (303) and the upper surface of the second primary mirror (304) are bonded together with optical epoxy adhesive. The outer cylindrical surface of the second primary mirror (304) is connected to the main load-bearing mounting flange (302) of the main load-bearing cylinder (301) through the primary mirror adapter hinge (305).

8. The laser beam expander unit with secondary mirror focusing function according to claim 7, characterized in that, The primary mirror adapter hinge (305) includes: The annular body (306) has its inner ring surface and the outer cylindrical surface of the second primary mirror (304) bonded together with optical epoxy adhesive. The annular body (306) has evenly distributed arc-shaped grooves around its circumference. And three L-shaped connecting ears (307) evenly distributed on the outer surface of the annular body (306); the three L-shaped connecting ears (307) are connected by screws and the main load-bearing mounting flange (302) of the main load-bearing cylinder (301); a straight groove is machined on one end of the L-shaped connecting ear (307) and the annular body (306), and the arc groove on the annular body (306) and the straight groove on the L-shaped connecting ear (307) serve as flexible links (308).

9. A method for adjusting the focusing mechanism of a laser beam expander unit with secondary mirror focusing function as described in claim 1, characterized in that, The adjustment method of the focusing mechanism is as follows: grind the bottom surface of the mounting base (602) and the mounting surface of the linear guide rail (603) so that the bottom surface of the mounting base (602) is perpendicular to the mounting surface of the linear guide rail (603); install the linear guide rail (603) and the dial indicator (606) so that the movement direction of the dial indicator (606) is perpendicular to the reference surface of the bottom surface of the mounting base (602); fix the mounting base (602) on the marble table (601); the laser beam expander unit is installed on the marble table (601) through the support hinge (8); move the dial indicator (606) up and down to measure the reference surface of the three sliding guide rails (501), and repeatedly adjust the position of the sliding guide rails (501) according to the measured reference surface of the three sliding guide rails (501) so that the movement direction of the three sliding guide rails (501) is parallel to that of the secondary mirror unit (1) and the intermediate support cylinder (2); after the adjustment is completed, record the data, and use a coordinate measuring machine to perform final data inspection to complete the adjustment.

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