Multi-pass optical system of off-axis two-mirror disc laser and its adjusting method

Abstract

This invention relates to a multi-pass optical path system and its adjustment method for an off-axis dual-reflector disk laser, overcoming a series of problems associated with existing multi-pump schemes for disk lasers, such as high processing requirements, difficult system assembly and adjustment, and complex structure and difficult optical adjustment of the signal light amplification system. This invention employs a combination of a series of small-aperture spherical or aspherical mirrors and total reflection mirrors, utilizing a discrete adjustment method to uniformly distribute the pump spot across different mirror surfaces, achieving multi-pass pumping of the pump light and improving the beam quality of the output laser. Simultaneously, a focusless system structure is used to achieve multi-pass amplification of the signal light, improving the operability of optical adjustment. Furthermore, the system can achieve a common optical path for pumping and amplification, facilitating high-efficiency absorption of the pump light and optimal signal light gain amplification; it also allows for adjustment of the number of multi-passes, resulting in high system flexibility, low processing and debugging difficulty, convenient equipment maintenance, and ease of industrial application.

Description

Technical Field

[0001] This invention belongs to the field of laser technology, specifically relating to a multi-path optical system and its adjustment method based on an off-axis dual-reflection disk laser. Background Technology

[0002] Solid-state lasers, with their advantages of high output power, high beam quality, and compact and simple structure, are increasingly widely used in various fields such as large-scale mechanical cutting, precision surgery, and even laser ignition fusion. However, for traditional rod-shaped solid-state lasers, the radial temperature field distribution caused by their own structure and limited cooling methods will induce axial thermal elongation and radial refractive index gradient in the laser medium, resulting in a severe thermal lensing effect. This distorts the beam wavefront and polarization state, leading to a degradation in the beam quality of the emitted laser, which restricts the realization and application of higher-power solid-state lasers.

[0003] The invention of the disk laser provides a new approach for the further development of high-power solid-state lasers. Unlike traditional rod-shaped solid-state lasers, disk lasers employ an end-pump-like structure to achieve optimal heat dissipation in one-dimensional heat flow, and typically use a disk-shaped laser crystal with a thickness of only a few hundred micrometers as the gain medium. The large aspect ratio of the gain medium means that only a one-dimensional thermal gradient exists along the beam propagation direction within the disk medium, while the thermal gradient in the radial direction is negligible. This greatly improves cooling efficiency, suppresses the thermal effects of the gain medium, and alleviates effects such as thermal lensing and thermal distortion, maintaining high beam quality even at high output power. Due to the characteristics of the disk laser gain medium, its thickness in the beam propagation direction is very thin (typically 100-200 μm), resulting in low single-pass absorption efficiency of the pump light. Therefore, a multi-pass optical path is needed to allow the pump light to pass through the gain medium multiple times to improve pump absorption efficiency. Currently, multiple pumping methods for disk lasers mainly employ: single parabolic spatial rotation, multiple sets of folding prisms, combinations of parabolic mirrors and multiple sets of folding prisms, and large-aperture symmetrical parabolic mirrors. However, these pumping schemes suffer from uneven mirror heating and severe surface distortion due to the pump light passing through the same mirror group multiple times and the beam position shifting. This results in pump light distortion, affecting the output beam quality. Furthermore, the single parabolic spatial rotation scheme and the large-aperture symmetrical parabolic mirror scheme, using a single mirror group, are difficult to fabricate and debug, have low utilization of the effective mirror area, a fixed and limited number of pumping cycles, poor system flexibility, and low pump light absorption efficiency.

[0004] Furthermore, disk solid-state lasers can also achieve signal amplification through suitable multi-pass optical path schemes. To optimize mode matching, multi-pass amplification systems for lasers typically employ image transfer systems rather than free-transmission systems. Given the relatively simple structure of 4f imaging systems, multiple optical paths can be implemented using fewer optical components, and this system ensures that the light spot incident on the gain medium does not undergo significant deformation each time. Therefore, most mature disk solid-state laser amplification systems are currently based on 4f imaging systems. However, traditional 4f imaging systems have a significant drawback: the presence of a real focal point on their spectral plane. To prevent air breakdown and ionization, experiments typically use vacuum tubes to place the system in a vacuum environment, which significantly increases the system's complexity and introduces a series of challenges for optical adjustment.

[0005] Based on the above problems, disk solid-state lasers urgently need a simple and effective multi-pass optical path method to realize the multi-pass pumping of pump light and the multi-pass amplification of signal light. Summary of the Invention

[0006] To overcome a series of problems existing in multiple-pump schemes of disk lasers, such as pump spot thermal distortion, high system fabrication and assembly difficulty, poor flexibility, low pump light absorption efficiency, and complex structure and difficult optical adjustment of signal light amplification based on 4f imaging systems, this invention provides a multi-pass optical path system and its adjustment method based on an off-axis dual-mirror disk laser. Based on the off-axis dual-mirror optical path system, a series of small-aperture spherical or aspherical mirrors and total reflection mirrors are used (it should be noted that "small-aperture" here refers to a smaller aperture than that used in existing technologies to achieve the same effect, and there is no specific numerical range). This disperses the pump spot across different mirror surfaces, avoiding the thermal distortion of the pump spot caused by multiple reflections of pump light by a single mirror, and improving the beam quality of the output laser. Meanwhile, the use of a focusless system structure enables pumping and amplification to share a common optical path, eliminating the need to consider air breakdown issues and facilitating high-power laser output and superior signal light gain amplification. On the other hand, this invention allows for adjustment of the number of multiple passes in the optical path, avoiding the problems of poor system flexibility and low conversion efficiency caused by the fixed and limited number of pumps in existing methods. This improves the quality of the output beam while reducing the difficulty of processing and debugging.

[0007] The technical solution of this invention is to provide a multi-path optical system based on an off-axis dual-reflection disk laser. The disk laser includes a disk laser crystal, and its special feature is that it includes n subsystems and m total reflection mirrors. The pump light passes through each subsystem to pump the disk laser crystal twice, and the signal light passes through each subsystem to be amplified twice within the disk laser crystal. Each total reflection mirror is used to reflect the pump light or signal light emitted from the previous subsystem to the next subsystem for further pump or signal light amplification. Wherein, n is an integer greater than or equal to 2, and m is an integer greater than or equal to 1.

[0008] Each subsystem includes a first mirror group and a second mirror group. The first mirror group includes two mirrors with the same focal length and adjustable angle, defined as the first mirror and the second mirror. The second mirror group includes two mirrors with the same focal length and adjustable angle, defined as the third mirror and the fourth mirror.

[0009] The centers of n first reflectors and n second reflectors are located on the first reference plane and are centrally symmetrically distributed; the centers of n third reflectors and n fourth reflectors are located on the second reference plane and are centrally symmetrically distributed.

[0010] The first reference plane, the second reference plane, and the plane containing the disk laser crystal are parallel to each other, and the centers of the first reference plane and the second reference plane are on the same horizontal line as the center of the disk laser crystal; the horizontal distance d1 between the first reference plane and the second reference plane is determined based on the afocal system.

[0011] In each subsystem, the optical axes of the first and second reflectors are parallel to each other, and the distance between the first and second reflectors and their center of symmetry on the first reference plane is greater than the distance between the third and fourth reflectors and their center of symmetry on the second reference plane. The pump light or signal light is incident horizontally on the first reflector parallel to its optical axis, and then is reflected sequentially by the third reflector, the disk laser crystal, the fourth reflector, and the second reflector, and exits along the optical axis of the second reflector.

[0012] The emitted light from the first subsystem is reflected by the total internal reflection mirror and enters the second subsystem for a second pump or signal amplification. The emitted light is then reflected by the total internal reflection mirror and enters the next subsystem for the next set of pump or signal amplification, and so on, until n sets of pump or signal amplification are completed.

[0013] Furthermore, for the beam-shrinking system, the first and second reflecting mirrors are both concave mirrors, and the third and fourth reflecting mirrors are both convex mirrors; for the beam-expanding system, the first and second reflecting mirrors are both convex mirrors, and the third and fourth reflecting mirrors are both concave mirrors.

[0014] Furthermore, the surface shape of the first, second, third, and fourth reflecting mirrors is spherical or aspherical, and the aspherical surface includes quadratic surface, higher-order aspherical surface, and freeform surface, etc.

[0015] Furthermore, the front surface of the disk laser crystal is coated with an anti-reflection film, and the rear surface is coated with an anti-reflection film, so that the pump light or signal light is reflected by the anti-reflection film on the rear surface after passing through the inside of the disk laser crystal.

[0016] Furthermore, the centers of the n first reflectors and the n second reflectors are located on the first reference plane and are centrally symmetrically distributed in the form of circles, rectangles, etc.; the arrangement of the n third reflectors and the n fourth reflectors is consistent with that of the first reflectors and the second reflectors.

[0017] Furthermore, the horizontal distance d1 between the first reference plane and the second reference plane is determined based on equation (1):

[0018] d1 / cosα=f1+f2 (1)

[0019] Where f1 and f2 are the focal lengths of the corresponding mirrors on the first and second reference planes, respectively, and α is the angle between the horizontal incident (exit) beam and the normal of the first (fourth) mirror.

[0020] Furthermore, the perpendicular distance d2 between the first and third mirrors, and between the second and fourth mirrors, satisfies equation (2):

[0021] d2 / d1=tanα (2)

[0022] The vertical distance d2 between the first and third reflecting mirrors is defined as the vertical distance between the centers of the first and third reflecting mirrors.

[0023] The present invention also provides an adjustment method for the multi-path optical system of the above-mentioned disk laser based on off-axis dual reflection, which is characterized by including the following steps:

[0024] Step 1: Adjust the pitch and deflection angles of the first and third reflectors of the first subsystem so that the pump light or signal light passes through the first and third reflectors in sequence and is incident on the disk laser crystal at an angle θ with the horizontal direction.

[0025] Step 2: Adjust the pitch and deflection angles of the fourth and second reflectors of the first subsystem so that the pump light or signal light emitted from the disk laser crystal passes through the fourth and second reflectors in sequence and is emitted along the optical axis of the second reflector.

[0026] Step 3: Adjust the total reflection mirror so that the emitted pump light or signal light enters the next subsystem;

[0027] Step 4: Repeat steps 1, 2 and 3 in the next subsystem, adjusting the corresponding reflectors until the emitted light is emitted along the optical axis of the second reflector of the nth subsystem, thus completing the amplification of n sets of pump or signal light.

[0028] The beneficial effects of this invention are:

[0029] 1. This invention utilizes a combination of a series of small-aperture spherical or aspherical mirrors and total reflection mirrors, and employs a discrete adjustment method to ensure that the pump spot is evenly distributed on different mirror surfaces. This ensures that each mirror surface only bears the pump light reflection once, avoiding the thermal distortion of the pump spot caused by multiple reflections of the pump light by a single mirror, and improving the beam quality of the output laser.

[0030] 2. Compared with using a pair (or individual) large-aperture parabolic mirrors, this method improves the utilization efficiency of the mirror surface area while reducing processing difficulty and precision. If a single mirror is damaged, the damaged component can be precisely replaced without reinstalling and debugging the system, extending its service life and significantly reducing system maintenance time and economic costs.

[0031] 3. Each reflector can be installed independently and adjusted flexibly. The number of optical passes can be controlled by adjusting the number of reflectors, their arrangement, pitch angle, and horizontal angle.

[0032] 4. This method can flexibly adjust the spatial dimensions of the system to meet actual needs by changing the focal length of each spherical or aspherical reflector and adjusting the positional relationship between the total reflection mirrors.

[0033] 5. During signal amplification, the multi-path optical system based on the focalless system with spatial arrangement avoids the solid focal point that occurs in the traditional 4f imaging method. Optical adjustment is easy to achieve, thereby improving the thermal stability of the system and the beam quality of the output laser. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the principle of a group of subsystems in a multi-channel optical path system based on an off-axis dual-reflection disk laser in an embodiment.

[0035] Figure 2 This is a schematic diagram of a multi-path optical system based on an off-axis dual-reflection disk laser in an embodiment.

[0036] Figure 3 This is a front view of the multi-path optical system of an off-axis dual-reflection disk laser in an embodiment.

[0037] Figure 4 yes Figure 3 The left view.

[0038] The reference numerals in the diagram are as follows: 01, First reflector; 02, Third reflector; 3, Disk laser crystal; 04, Fourth reflector; 05, Second reflector; 1, First reflector of the first subsystem; 2, Third reflector of the first subsystem; 4, Fourth reflector of the first subsystem; 5, Second reflector of the first subsystem; 6, First total internal reflection mirror; 7, First reflector of the second subsystem; 8, Third reflector of the second subsystem; 9, Fourth reflector of the second subsystem; 10, Second reflector of the second subsystem; 11, Second total internal reflection mirror; 12, Third total internal reflection mirror; 13, First reflector of the third subsystem; 14, Third reflector of the third subsystem; 15, Fourth reflector of the third subsystem; 16, Second reflector of the third subsystem; 17, Fourth total internal reflection mirror; 18, First reflector of the fourth subsystem; 19, Third reflector of the fourth subsystem; 20, Fourth reflector of the fourth subsystem; 21, Second reflector of the fourth subsystem.

[0039] a. First reference plane; b. Second reference plane; d1. Horizontal distance between the first and second reference planes; d2. Vertical distance between the first and third reflecting mirrors; α. Angle between the horizontal incident (exit) beam and the normal of the first (second) reflecting mirror; F1′. Focal point of the first reflecting mirror; F5. Focal point of the second reflecting mirror. Detailed Implementation

[0040] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0041] like Figure 1 The diagram shown is a schematic representation of a set of subsystems in the multi-pass optical path system of the off-axis dual-reflection disk laser in this embodiment. Figure 2 and Figure 4 As shown, this embodiment uses a multi-path optical system based on an off-axis dual-reflection disk laser, comprising a total of 4 groups. Figure 1 The diagram shows the subsystem and four total reflection mirrors. In other embodiments, the number of subsystems can be adjusted according to the actual number of pumping and amplification cycles. The pump light performs two-pass pumping on the disk laser crystal 3 after passing through each set of subsystems, and the signal light undergoes two amplifications within the disk laser crystal 3 after passing through each set of subsystems. Each total reflection mirror reflects the pump light or signal light emitted from the previous set of subsystems to the next set of subsystems for the next pumping or signal light amplification. As shown above, by adding total reflection mirrors and subsystems, the off-axis dual-reflector subsystem can be continuously cycled until a satisfactory upper limit for the number of pumping (amplification) cycles is reached.

[0042] from Figure 1As can be seen, each subsystem in this embodiment includes four mirrors, which can be defined as the first mirror 01, the second mirror 05, the third mirror 02, and the fourth mirror 04. In each subsystem, the optical axes of the first mirror 01 and the second mirror 05 are parallel, have the same focal length, and are adjustable in angle; the third mirror 02 and the fourth mirror 04 have the same focal length and are adjustable in angle. This embodiment is a beam-shrinking system, therefore the first mirror 01 and the second mirror 05 are both concave mirrors, and the third mirror 02 and the fourth mirror 04 are both convex mirrors; for a beam-expanding system, the first mirror 01 and the second mirror 05 are both convex mirrors, and the third mirror 02 and the fourth mirror 04 are both concave mirrors. The surface shape of the first mirror 01, the second mirror 05, the third mirror 02, and the fourth mirror 04 is spherical or aspherical. Aspherical surfaces can be quadratic surfaces, higher-order aspherical surfaces, and freeform surfaces, etc. This embodiment uses a spherical mirror as an example for explanation.

[0043] For ease of description, the four subsystems are defined as the first subsystem, the second subsystem, the third subsystem, and the fourth subsystem, respectively. The four mirrors of the first subsystem are defined as mirror 1 (first mirror), mirror 5 (second mirror), mirror 2 (third mirror), and mirror 4 (fourth mirror); the four mirrors of the second subsystem are defined as mirror 7 (first mirror), mirror 10 (second mirror), mirror 8 (third mirror), and mirror 9 (fourth mirror); the four mirrors of the third subsystem are defined as mirror 13 (first mirror), mirror 16 (second mirror), mirror 14 (third mirror), and mirror 15 (fourth mirror); and the four mirrors of the fourth subsystem are defined as mirror 18 (first mirror), mirror 21 (second mirror), mirror 19 (third mirror), and mirror 20 (fourth mirror). Figures 2 to 4 As shown.

[0044] In this embodiment, the centers of all first and second reflectors are located on the same plane, which can be defined as the first reference plane a. The centers of all third and fourth reflectors are located on the same plane, which can be defined as the second reference plane b. (See...) Figure 1 .like Figure 4As shown, the first reflector 1, the second reflector 5, the first reflector 7, the second reflector 10, the first reflector 13, the second reflector 16, the first reflector 18, and the second reflector 21 of the fourth subsystem are coplanar, with their centers all located on the first reference plane a. They are arranged in a circular, centrally symmetrical distribution on the first reference plane a. In other embodiments, they may also be arranged in other forms, such as a rectangular, centrally symmetrical distribution. The third reflector 2, the fourth reflector 4, the third reflector 8, the fourth reflector 9, the third reflector 14, the fourth reflector 15, the third reflector 19, and the fourth reflector 20 of the fourth subsystem are coplanar, with their centers all located on the second reference plane b. They are also arranged in a circular, centrally symmetrical distribution on the second reference plane b. In other embodiments, they may also be arranged in other forms, such as a rectangular, centrally symmetrical distribution. It should be noted that the arrangement of the third and fourth reflectors must be consistent with the arrangement of the first and second reflectors.

[0045] Combination Figure 1 It can be seen that the plane containing the first reference plane a, the second reference plane b, and the disk laser crystal 3 is parallel to each other, and the centers of the first reference plane a and the second reference plane b are on the same horizontal line as the center of the disk laser crystal 3; the horizontal distance d1 between the first reference plane a and the second reference plane b is determined based on the afocal system.

[0046] d1 / cosα=f1+f2 (1)

[0047] Where f1 and f2 are the focal lengths of the corresponding mirrors on the first reference plane a and the second reference plane b, respectively, and α is the angle between the horizontal incident beam and the normal of the first mirror 01.

[0048] In each subsystem, the distance between the first reflector 01 and the second reflector 02 on the first reference plane a and their center of symmetry is greater than the distance between the third reflector 03 and the fourth reflector 04 on the second reference plane and their center of symmetry; the perpendicular distance d2 between the first reflector 01 and the third reflector 03, and between the second reflector 02 and the fourth reflector 04, satisfies equation (2):

[0049] d2 / d1=tanα (2)

[0050] Combination Figures 2 to 4 The specific pumping or amplification is achieved through the following adjustment process:

[0051] 1. Adjust the pitch and deflection angles of the first reflector 1, the third reflector 2, the fourth reflector 4, and the second reflector 5 of the first subsystem so that the pump light or signal light passes sequentially through the first reflector 1 and the third reflector 2 of the first subsystem and is incident on the disk laser crystal 3 at an angle θ (θ > 0) with the horizontal, and exits through the fourth reflector 4 and the second reflector 5 of the first subsystem, so that the pump light or signal light passes through the disk laser crystal 3 for the first time.

[0052] The front surface of the disk laser crystal 3 is coated with an anti-reflection film, and the rear surface is coated with an anti-reflection film. This allows the pump light or signal light to be reflected by the total internal reflection film on the rear surface after passing through the inside of the crystal. Therefore, the pump light or signal light passes through the disk crystal once, which corresponds to two passes inside the crystal, thus realizing two-pass pump or two-pass signal light amplification.

[0053] 2. Adjust the first total reflection mirror 6 so that the pump light or signal light after being emitted passes through the first total reflection mirror 6 and then enters the first reflection mirror 7 of the second subsystem.

[0054] 3. Adjust the first reflector 7, the third reflector 8, the fourth reflector 9, and the second reflector 10 of the second subsystem so that the pump light or signal light passes through the first reflector 7 and the third reflector 8 of the second subsystem in sequence and is incident on the disk laser crystal 3 for the second time, and exits through the fourth reflector 9 and the second reflector 10 of the second subsystem so that the pump light or signal light passes through the disk laser crystal 3 for the second time.

[0055] 4. By adjusting the pitch and deflection angles of the second total reflection mirror 11 and the third total reflection mirror 12, the pump light or signal light is incident on the first reflection mirror 13 of the third subsystem after passing through the second total reflection mirror 11 and the third total reflection mirror 12.

[0056] 5. Adjust the first reflector 13, the third reflector 14, the fourth reflector 15, and the second reflector 16 of the third subsystem so that the pump light or signal light passes through the first reflector 13 and the third reflector 14 of the third subsystem for the second time into the disk laser crystal 3, and exits through the fourth reflector 15 and the second reflector 16 of the third subsystem, so that the pump light or signal light passes through the disk laser crystal 3 for the third time.

[0057] 6. By adjusting the fourth total internal reflection mirror 17, the pump light passes through the fourth total internal reflection mirror 17 and then enters the first reflection mirror 18 of the fourth subsystem.

[0058] 7. Adjust the first reflector 18, the third reflector 19, the fourth reflector 20, and the second reflector 21 of the fourth subsystem so that the pump light or signal light passes through the first reflector 18 and the third reflector 19 of the fourth subsystem for the fourth time into the disk laser crystal 3, and exits through the fourth reflector 20 and the second reflector 21 of the fourth subsystem, so that the pump light or signal light passes through the disk laser crystal 3 for the fourth time.

[0059] To more clearly describe the transmission characteristics of pump light or signal light in this system. Figure 3 and Figure 4 The front and left views of this multi-path optical example are described respectively. In this example, the order in which the light passes through the optical elements during transmission is: 1→2→3→4→5→6→7→8→3→9→10→11→12→13→14→3→15→16→17→18→19→3→20→21. From the route diagram, it can be calculated that the pump light or signal light passes through the disk laser crystal 3 4 times. Since one reflection of the pump light or signal light in the disk crystal corresponds to two transits inside the crystal, the number of times the disk laser crystal 3 is pumped (amplified) reaches 4*2=8 times.

[0060] As can be seen from the optical path transmission process, by reasonably setting the number and arrangement of total reflection mirrors, concave mirrors and convex mirrors, the number of times the multi-channel optical path is adjusted can be flexibly adjusted, thereby controlling the number of times the pump light or signal light passes through the disk laser crystal 3.

[0061] The above description is merely an embodiment of the present invention. It should be noted that any modifications made by those skilled in the art without departing from the concept of the present invention, such as changes to the arrangement of concave and convex mirrors, structural features involving positional changes, or other implementation details of the present invention, are all within the scope of protection of the present invention.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A multi-path optical system based on an off-axis dual-reflection disk laser, wherein the disk laser comprises a disk laser crystal, characterized in that: It includes n subsystems and m total internal reflection mirrors; the pump light passes through each subsystem to pump the disk laser crystal twice, and the signal light passes through each subsystem to be amplified twice within the disk laser crystal; each total internal reflection mirror is used to reflect the pump light or signal light emitted from the previous subsystem to the next subsystem for the next pump or signal light amplification; where n is an integer greater than or equal to 2, and m is an integer greater than or equal to 1; Each subsystem includes a first mirror group and a second mirror group. The first mirror group includes two mirrors with the same focal length and adjustable angle, defined as the first mirror and the second mirror. The second mirror group includes two mirrors with the same focal length and adjustable angle, defined as the third mirror and the fourth mirror. The centers of n first reflectors and n second reflectors are located on the first reference plane and are centrally symmetrically distributed; the centers of n third reflectors and n fourth reflectors are located on the second reference plane and are centrally symmetrically distributed. The first reference plane, the second reference plane, and the plane containing the disk laser crystal are parallel to each other, and the centers of the first reference plane and the second reference plane are on the same horizontal line as the center of the disk laser crystal; the horizontal distance d1 between the first reference plane and the second reference plane is determined based on the afocal system. In each subsystem, the optical axes of the first and second reflectors are parallel to each other, and the distance between the first and second reflectors and their center of symmetry on the first reference plane is greater than the distance between the third and fourth reflectors and their center of symmetry on the second reference plane. The pump light or signal light is incident horizontally on the first reflector parallel to its optical axis, and then is reflected sequentially by the third reflector, the disk laser crystal, the fourth reflector, and the second reflector, and exits along the optical axis of the second reflector. The emitted light from the first subsystem is reflected by the total internal reflection mirror and enters the second subsystem for the second set of pump or signal light amplification. The emitted light is then reflected by the total internal reflection mirror and enters the next set of subsystems for the next set of pump or signal light amplification, and so on, until n sets of pump or signal light amplification are completed.

2. The multi-path optical system based on an off-axis dual-reflection disk laser according to claim 1, characterized in that: The first and second reflecting mirrors are both concave mirrors, and the third and fourth reflecting mirrors are both convex mirrors; or, the first and second reflecting mirrors are both convex mirrors, and the third and fourth reflecting mirrors are both concave mirrors.

3. The multi-path optical system based on an off-axis dual-reflection disk laser according to claim 2, characterized in that: The surface shape of the first, second, third, and fourth reflecting mirrors is either spherical or aspherical. Aspherical surfaces include quadratic surfaces, higher-order aspherical surfaces, and freeform surfaces.

4. The multi-path optical system based on an off-axis dual-reflection disk laser according to claim 3, characterized in that: The front surface of the disc laser crystal is coated with an antireflection coating, and the back surface is coated with an antireflection coating.

5. The multi-path optical system based on an off-axis dual-reflection disk laser according to claim 4, characterized in that: The n first reflectors and n second reflectors are centered on the first reference plane and are symmetrically distributed in a circle or rectangle; the arrangement of the n third reflectors and n fourth reflectors is consistent with that of the first and second reflectors.

6. The multi-path optical system based on an off-axis dual-reflection disk laser according to claim 5, characterized in that: The horizontal distance d1 between the first and second reference planes is determined based on equation (1): d1 / cosα=f1+f2 (1) Where f1 and f2 are the focal lengths of the corresponding mirrors on the first and second reference planes, respectively, and α is the angle between the horizontal incident beam and the normal of the first mirror.

7. The multi-path optical system based on an off-axis dual-reflection disk laser according to claim 6, characterized in that: The perpendicular distance d2 between the first and third mirrors, and between the second and fourth mirrors, satisfies equation (2): d2 / d1=tanα (2).

8. A method for adjusting a multi-path optical system based on an off-axis dual-reflection disk laser as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Adjust the pitch and deflection angles of the first and third reflectors of the first subsystem so that the pump light or signal light passes through the first and third reflectors in sequence and is incident on the disk laser crystal at an angle θ with the horizontal direction. Step 2: Adjust the pitch and deflection angles of the fourth and second reflectors of the first subsystem so that the pump light or signal light emitted from the disk laser crystal passes through the fourth and second reflectors in sequence and is emitted along the optical axis of the second reflector. Step 3: Adjust the total reflection mirror so that the emitted pump light or signal light enters the next subsystem; Step 4: Repeat steps 1, 2 and 3 in the next subsystem, adjusting the corresponding reflectors until the emitted light is emitted along the optical axis of the second reflector of the nth subsystem, thus completing the amplification of n sets of pump or signal light.

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