A UV laser

Abstract

The present application provides an ultraviolet laser, which includes, in order, a pump source, a collimating lens, a focusing lens, a first cavity mirror, a gain medium, a Q-switching element, and a second cavity mirror in the first direction; a third cavity mirror and a displacement motor in the second direction; a first spectrometer, a frequency-doubling crystal, and a fourth cavity mirror in the third direction; a fifth cavity mirror in the fourth direction; and a second focusing lens 23, a second frequency-doubling crystal 25, a second collimating lens 26, a sixth cavity mirror 27, and a second spectrometer 28 in the fifth direction. The present application achieves adjustable cavity length by moving the displacement motor to drive the third cavity mirror in the second direction, thereby enabling the ultraviolet laser to obtain a cavity length adapted to the corresponding power output at different output powers. Consequently, a highly integrated ultraviolet laser with precisely adjustable cavity length, compatible with multiple high- and low-power overlapping stable outputs, and a compact structure is obtained.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, and more particularly to an ultraviolet laser with adjustable cavity length and high stability. Background Art

[0002] In recent years, with the growing demand of the new energy industry, higher requirements have been placed on front-end laser processing technology. The stability of the laser has a huge impact on the laser, especially when the laser is used in precision processing. The influence of the cavity length on the stability of the laser is particularly critical. We know that the stability conditions of the resonant cavity are: The curvatures R1 and R2 of the laser cavity mirror are generally specific in actual use. The controllable cavity length L can greatly improve the actual use effect of the laser. The influence of thermal lens in the actual operation of high-power solid-state lasers cannot be ignored. Traditional solid-state lasers can achieve relatively stable laser output under a certain state. When the application end requires the use of high and low power overlapping light output operations, one laser can no longer meet the needs, or when the application end requires lasers of different powers to operate, it cannot be compatible. Ultraviolet lasers have a shorter wavelength than infrared and have greater photon energy. As a result, they can perform precision processing in more delicate fields and are very popular in society. Their stability directly determines the yield rate of precision processing.

[0003] Based on this, it is necessary to invent an ultraviolet laser that can obtain ultraviolet laser output with adjustable cavity length, high stability and compact structure. Summary of the Invention

[0004] The purpose of this application is to provide an ultraviolet laser to solve the problems raised in the above background technology.

[0005] To achieve the above objectives, this application provides the following technical solutions:

[0006] The present application provides an ultraviolet laser that can achieve the technical effects of ultraviolet laser output with adjustable cavity length, high stability, and compact structure. The ultraviolet laser comprises, in order in the first direction, a pump source, a first collimating lens, a first focusing lens, a first cavity mirror, a gain medium, a Q-switching element, and a second cavity mirror; in order in the second direction, a third cavity mirror and a displacement motor; in order in the third direction, a first spectrometer, a first frequency-doubling crystal, and a fourth cavity mirror; the third cavity mirror is located behind the second cavity mirror in the second direction, and the first spectrometer is located behind the first cavity mirror in the third direction. In the fourth direction, a fifth cavity mirror is also included, which is located behind the first spectrometer in the fourth direction, at a 45° angle to the optical path in the fourth direction, and is located on the side close to the third cavity mirror. In the fifth direction, the ultraviolet laser comprises, in order, a second focusing lens, a second frequency-doubling crystal, a second collimating lens, a sixth cavity mirror, and a second spectrometer; the second focusing lens is located behind the fifth cavity mirror in the fifth direction.

[0007] The pump source is typically a semiconductor laser that emits an infrared beam of approximately 808nm / 880nm. After being output via a fiber optic patch cord and collimated by a first collimating lens, the infrared beam is converged by the first focusing lens as it passes through the first cavity mirror and is focused within the gain medium. The pump source, fiber optic patch cord, first collimating lens, and first focusing lens together constitute the pump coupling module of the ultraviolet laser of this application.

[0008] The Q-switching element can control the power pulses required for operation.

[0009] The first cavity mirror, the second cavity mirror, the third cavity mirror, the fourth cavity mirror, the first optical splitter, the fifth cavity mirror and the sixth cavity mirror together constitute the resonant module of the ultraviolet laser of the present application, that is, the resonant cavity.

[0010] The resonance principle of the ultraviolet laser of this application is as follows: pump light passing through the first cavity mirror undergoes stimulated radiation in the gain medium, generating a 1000-1100nm infrared beam. The corresponding side surfaces of the first, second, third, and fourth cavity mirrors are coated with a reflective film. The 1000-1100nm infrared beam passes through the second, third, and fourth cavity mirrors, then returns to the first cavity mirror, continuously reflecting to form a first loop. When the pump source continuously provides excitation, the 1000-1100nm infrared photons continuously resonate in this loop.

[0011] The 1000-1100nm beam in the first loop undergoes a nonlinear effect when passing through the first frequency-doubling crystal, generating a 500-550nm beam. This beam is then retraced through the fourth cavity mirror, reflected by the first beam splitter to the fifth cavity mirror, and then reflected by the fifth cavity mirror to the second frequency-doubling crystal for transformation. The remaining 500-550nm beam is then retraced through the sixth cavity mirror, passing through the second frequency-doubling crystal again, and then through the fifth cavity mirror. After reflection from the first beam splitter, it reaches the fourth cavity mirror, completing the second loop.

[0012] The 500-550nm green light beam reflected and output by the first beam splitter is reflected by the fifth cavity mirror and then converged by the second focusing lens. This beam is then focused within the second frequency-doubling crystal. The beam is then collimated by the second collimating lens and reflected by the sixth cavity mirror. Finally, the 250-275nm high-reflection coating of the second beam splitter is used to efficiently and stably output the 250-275nm ultraviolet laser in the sixth direction.

[0013] To match the high and low powers generated by the UV laser, eliminate the adverse effects of thermal lensing on the stability of the resonant cavity at different powers, and achieve highly stable UV laser output, the third cavity mirror is fixed to a displacement motor. By moving the displacement motor, the third cavity mirror moves in a second direction, thereby achieving adjustable cavity length. Simultaneously, the movement of the third cavity mirror in the second direction does not alter the optical path of the entire UV laser when adjusting the cavity length, thus ensuring the stability of the UV laser output.

[0014] The present application designs a resonant cavity with two loops and a compact structure, and then uses a movable displacement motor to drive the third cavity mirror to move in the second direction, thereby achieving adjustable cavity length. The ultraviolet laser can adjust the cavity length to obtain a cavity length suitable for the corresponding power output under different output powers, so that the output power can be stable and continuous. Furthermore, a ultraviolet laser with precisely adjustable cavity length, compatible with multiple high and low power overlapping stable outputs, high integration, and compact structure is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions of the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0016] Figure 1 A schematic diagram of the first structure of the ultraviolet laser provided in this application;

[0017] Figure 2A second structural schematic diagram of the ultraviolet laser provided in this application;

[0018] Figure 3 A third structural diagram of the ultraviolet laser provided in this application;

[0019] Figure 4 A fourth structural schematic diagram of the ultraviolet laser provided in this application;

[0020] Figure 5 This is a fifth structural schematic diagram of the ultraviolet laser provided in this application.

[0021] Figure numerals: 1. pump source, 2. first collimating lens, 3. first focusing lens, 4. first cavity mirror, 5. gain medium, 6. first pinhole aperture, 7. Q-switching element, 8. second pinhole aperture, 9. second cavity mirror, 10. third cavity mirror, 11. first idle light collector, 12. displacement motor, 13. third pinhole aperture, 14. first spectrometer, 15. first temperature control module, 16. first frequency doubling crystal, 17. fourth cavity mirror, 18. second idle light collector, 19. fourth pinhole aperture, 20. fifth cavity mirror, 22. third idle light collector, 23. second focusing lens, 24. second temperature control module, 25. second frequency doubling crystal, 26. second collimating lens, 27. sixth cavity mirror, 28. second spectrometer, 29. fourth idle light collector, 30. third spectrometer. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments. Obviously, the embodiments described are only part of the embodiments of the present application and are not intended to limit the scope of the rights of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0023] See also Figure 1 , Figure 1This is a schematic diagram of the first structure of the ultraviolet laser provided in the present application. The ultraviolet laser includes, in the first direction, a pump source 1, a first collimating lens 2, a first focusing lens 3, a first cavity mirror 4, a gain medium 5, a Q-switched element 7, and a second cavity mirror 9; in the second direction, it includes, in sequence, a third cavity mirror 10 and a displacement motor 12, and the third cavity mirror 10 is located behind the second cavity mirror 9 in the second direction. In the third direction, it includes, in sequence, a first spectrometer 14, a first frequency-doubling crystal 16, and a fourth cavity mirror 17, and the first spectrometer 14 is located behind the first cavity mirror 4 in the third direction. In the fourth direction, it also includes a fifth cavity mirror 20, which is located behind the first spectrometer 14 in the fourth direction, is placed at 45 degrees to the optical path in the fourth direction, and is located on the side close to the third cavity mirror 10. In the fifth direction, the second focusing lens 23, the second frequency-doubling crystal 25, the second collimating lens 26, the sixth cavity mirror 27, and the second beam splitter 28 are sequentially included. The second focusing lens 23 is located behind the fifth cavity mirror 20 in the fifth direction. The above structural arrangement can make the ultraviolet laser of the present application a highly integrated and compact laser.

[0024] The pump source 1 is generally a semiconductor laser that emits an infrared beam of approximately 808nm / 880nm. After being output via a fiber optic patch cord (not shown), the infrared beam is collimated by a first collimating lens 2 and then converged by a first focusing lens 3. After passing through a first cavity mirror 4, the beam is focused within a gain medium 5. In other words, the pump source 1, fiber optic patch cord, first collimating lens 2, and first focusing lens 3 together constitute the pump coupling module of the ultraviolet laser of this application.

[0025] The first cavity mirror 4, the second cavity mirror 9, the third cavity mirror 10, the fourth cavity mirror 17, the first optical splitter 14, the fifth cavity mirror 20 and the sixth cavity mirror 27 together constitute the resonant module of the ultraviolet laser of the present application, that is, the resonant cavity.

[0026] The resonance principle of the ultraviolet laser of the present application is as follows: the pump light passing through the first cavity mirror 4 undergoes stimulated radiation in the gain medium 5, generating a 1000-1100nm infrared beam. This beam is reflected by the second cavity mirror 9 to the third cavity mirror 10, after which it is retraced along its original path by the third cavity mirror 10. It is then reflected by the second cavity mirror 9 and the first cavity mirror 4 before being retraced along its original path by the fourth cavity mirror 17. The beam retraced by the fourth cavity mirror 17 is then reflected by the first cavity mirror 4, thus completing the first loop. When the pump source 1 continuously provides excitation, the 1000-1100nm infrared photons continuously resonate in this loop.

[0027] The 1000-1100nm beam in the first loop undergoes a nonlinear effect when passing through the first frequency-doubling crystal 16, generating a 500-550nm beam. This beam is then retraced by the fourth cavity mirror 17, reflected by the first beam splitter 14 to the fifth cavity mirror 20, and then reflected by the fifth cavity mirror 20 to the second frequency-doubling crystal 25 for transformation. The remaining 500-550nm beam is then retraced by the sixth cavity mirror 27, passing through the second frequency-doubling crystal 25 again, and then passing through the fifth cavity mirror 20 and the first beam splitter 14 before arriving at the fourth cavity mirror 17, thus completing the second loop. The first cavity mirror 4, second cavity mirror 9, third cavity mirror 10, fourth cavity mirror 17, first beam splitter 14, fifth cavity mirror 20, and sixth cavity mirror 27 together form the resonant cavity of two resonant circuits, with the first beam splitter 14 acting as both a dichroic mirror and a cavity mirror within the resonant cavity.

[0028] The 500-550nm green light beam reflected and output by the first spectrometer 14 is reflected by the fifth cavity mirror 20 and then converged by the second focusing lens 23 when passing through the second focusing lens 23, so that it is focused in the second frequency doubling crystal 25. The light beam is then collimated by the second collimating lens 26 and reflected by the sixth cavity mirror 27.

[0029] In order to ensure that the resonant cavity can operate efficiently, stably and normally, the side of the first cavity mirror 4 close to the first optical splitter 14 or the gain medium 5 is coated with a 1000-1100nm high reflection film, the side of the second cavity mirror 9 close to the Q-switched element 7 or the third cavity mirror 10 is coated with a 1000-1100nm high reflection film, the side of the third cavity mirror 10 close to the second cavity mirror 9 is coated with a 1000-1100nm high reflection film, and the side of the fourth cavity mirror 17 close to the first optical splitter 14 is coated with a 1000- The first beam splitter 14 is coated with a 500-550nm high-reflection film on the side close to the fourth cavity mirror 17. The fifth cavity mirror 20 is coated with a 500-550nm high-reflection film on the side close to the second focusing lens 23. The sixth cavity mirror 27 is coated with a 500-550nm high-reflection film on the side close to the second collimating lens 26. The second beam splitter 28 is coated with a 250-275nm high-reflection film on the side close to the sixth cavity mirror 27. The 250-275nm high-reflection film on the second beam splitter 28 is used to efficiently and stably output the 250-275nm ultraviolet laser light in the sixth direction.

[0030] The Q-switching element 7 can be controlled to form the required power pulse. In a specific embodiment, an acousto-optic Q-switching element can be used.

[0031] To match the high and low powers generated by the UV laser and achieve highly stable UV laser output, the third cavity mirror 10 is fixed to a displacement motor 12. By moving the displacement motor 12, the third cavity mirror 10 is driven to move in the second direction, thereby achieving adjustable cavity length. Simultaneously, the movement of the third cavity mirror 10 in the second direction does not alter the optical path of the entire UV laser when adjusting the cavity length, thus ensuring the stability of the UV laser output. The displacement motor 12 is a precision displacement motor, and its movement can be controlled by software.

[0032] In a preferred embodiment, the first cavity mirror 4 is placed at a 60° angle to the optical paths in the first and third directions, the second cavity mirror 9 is placed at a 45° angle to the optical paths in the first and second directions, and the second spectrometer 28 is placed at a 45° angle to the optical paths in the fifth and sixth directions. The components in the second and third directions are all arranged on the same side of the first direction, and the component in the fifth direction is arranged on the side of the fifth cavity mirror 20 away from the first direction. The above structural arrangement can make the ultraviolet laser of the present application a highly integrated and compact laser. At the same time, when the cavity length is adjusted, the optical path direction of the entire ultraviolet laser will not be changed, thereby ensuring the stability of the ultraviolet laser output.

[0033] Furthermore, in order to reduce the energy loss of the light beam and improve the overall light transmittance, the front and rear end faces of the first collimating lens 2, the first focusing lens 3, the first cavity mirror 4, the gain medium 5 and the Q-switched element 7 are all coated with 808 / 880nm anti-reflection coating, the second focusing lens 23 is coated with 500-550nm anti-reflection coating on both sides, the side of the second focusing lens 23 close to the second frequency-doubling crystal 25 is coated with 250-275nm high-reflection coating, and the second collimating lens 26 is coated with 500-550nm and 250-275nm anti-reflection coatings on both sides.

[0034] Furthermore, in order to fully and effectively utilize the light beam, the front and rear end faces of the gain medium 5, the Q-switching element 7 and the first spectrometer 14 are all coated with a 1000-1100nm anti-reflection film, the first frequency-doubling crystal 16 is coated with a 1000-1100nm and 500-550nm anti-reflection film on both sides, and the second frequency-doubling crystal 25 is coated with a 250-275nm and 500-550nm anti-reflection film on both sides.

[0035] Furthermore, in order to improve the overall working stability of the device, a heat sink structure is further provided on the gain medium 5 , and the heat sink structure promptly conducts away excess heat on the gain medium 5 .

[0036] Further, see Figure 2 , Figure 2This is a schematic diagram of the second structure of the UV laser provided in this application. To achieve more efficient and stable output of 250-275nm UV light and obtain a purer 250-275nm UV laser, a third beam splitter 30 is also included in the sixth direction. The third beam splitter 30 is located behind the second beam splitter 28 in the sixth direction. The third beam splitter 30 is coated with a 500-550nm high-reflection coating on the side closest to the second beam splitter 28, and a 250-275nm anti-reflection coating on both sides.

[0037] Furthermore, in order to reduce the interference of idle frequency light on resonance, both sides of the first cavity mirror 4 are coated with 500-550nm anti-reflection film, both sides of the second cavity mirror 9 and the third cavity mirror 10 are coated with 808 / 880nm and 500-550nm anti-reflection films, respectively, both sides of the fifth cavity mirror 20 are coated with 1000-1100nm anti-reflection film, and both sides of the second spectrometer 28 are coated with 500-550nm anti-reflection film.

[0038] Further, see Figure 3 , Figure 3 This is a third structural schematic diagram of the ultraviolet laser provided in the present application. The first frequency-doubling crystal 16 is externally provided with a first temperature control module 15, and the first temperature control module 15 provides a stable temperature environment for the first frequency-doubling crystal 16; the second frequency-doubling crystal 25 is also externally provided with a second temperature control module 24, and the second temperature control module 24 provides a stable temperature environment for the second frequency-doubling crystal 25, thereby improving the overall working stability of the device.

[0039] Further, see Figure 4 , Figure 4 This is a fourth structural diagram of the ultraviolet laser provided in this application. Figure 3 The ultraviolet laser shown in the figure may further include: a first pinhole aperture 6, a second pinhole aperture 8, a third pinhole aperture 13, and a fourth pinhole aperture 19. The first pinhole aperture 6 is located between the gain medium 5 and the Q-switched element 7 and can limit the mode, block off-axis stray light, and improve the optical path stability of the entire system. The second pinhole aperture 8 is located between the Q-switched element 7 and the second cavity mirror 9 and can filter out the diffracted light after passing through the Q-switched element 7. The third pinhole aperture 13 is located between the first cavity mirror 4 and the first beam splitter 14 and can similarly limit the mode, block off-axis stray light, and improve the optical path stability of the entire system. The fourth pinhole aperture 19 is located between the first beam splitter 14 and the fifth cavity mirror 20 and can limit the output of the green laser light, thereby improving the output quality of the green laser light.

[0040] Further, see Figure 5 , Figure 5This is a fifth structural diagram of the ultraviolet laser provided by this application. In order to reduce the interference of idle frequency light on the resonant operation and obtain stable ultraviolet laser output, the ultraviolet laser, Figure 4 On the basis of the ultraviolet laser shown, it also includes: a first idler light collector 11, a second idler light collector 18, a third idler light collector 22, and a fourth idler light collector 29; the first idler light collector 11 is located on the side of the second cavity mirror 9 away from the Q-switched element 7 in the first direction, and is mainly used to collect 808 / 880nm and 500-550nm idler light; the second idler light collector 18 is located on the side of the first cavity mirror 4 away from the first optical splitter 14 in the third direction, and mainly collects 500-550nm idler light; the third idler light collector 22 is located on the side of the fifth cavity mirror 20 away from the first optical splitter 14 in the fourth direction, and mainly collects 1000-1100nm idler light; the fourth idler light collector 29 is located on the side of the second optical splitter 28 away from the sixth cavity mirror 27 in the fifth direction, and mainly collects 500-550nm idler light. The first idler light collector 11, the second idler light collector 18, the third idler light collector 22, and the fourth idler light collector 29 are all used to absorb and dissipate heat from the residual fundamental frequency signal light. The residual fundamental frequency signal light and the incompletely reflected doubled frequency light passing through these devices will be annihilated in these idler light collectors, thereby improving the system stability and the purity of the output ultraviolet laser.

[0041] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device comprising a series of elements are inherent to the elements. In the absence of further restrictions, the elements defined by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device comprising the elements. In addition, the above-mentioned technical solutions provided in the embodiments of the present application are not described in detail in accordance with the corresponding technical solutions in the prior art to achieve the same principle, so as to avoid excessive elaboration.

[0042] Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only intended to help understand the method and core ideas of the present application. It should be noted that, for those skilled in the art, without departing from the principles of the present application, various improvements and modifications may be made to the present application, as well as combinations of the various embodiments in the present application. Such improvements, modifications, and combinations also fall within the scope of protection of the claims of the present application.

Claims

1. A UV laser, characterized in that , in the first direction, it includes a pump source (1), a first collimating lens (2), a first focusing lens (3), a first cavity mirror (4), a gain medium (5), a Q-switching element (7), and a second cavity mirror (9); In the second direction, it includes a third cavity mirror (10) and a displacement motor (12), wherein the third cavity mirror (10) is located behind the second cavity mirror (9) in the second direction; In the third direction, it includes a first optical splitter (14), a first frequency doubling crystal (16), and a fourth cavity mirror (17), wherein the first optical splitter (14) is located behind the first cavity mirror (4) in the third direction; A fifth cavity mirror (20) is also included in the fourth direction, and the fifth cavity mirror (20) is located behind the first light splitting device (14) in the fourth direction; In the fifth direction, the second focusing lens (23), the second frequency doubling crystal (25), the second collimating lens (26), the sixth cavity mirror (27), and the second light splitting device (28) are sequentially included, wherein the second focusing lens (23) is located behind the fifth cavity mirror (20) in the fifth direction; The pump source (1) is a semiconductor laser that emits an 808nm / 880nm infrared beam. After being output via an optical fiber jumper, the infrared beam is collimated by a first collimating lens (2). When the beam passes through a first focusing lens (3), it is converged by the first focusing lens (3) and focused in a gain medium (5) after passing through a first cavity mirror (4). The pump light passing through the first cavity mirror (4) generates stimulated radiation in the gain medium (5), generating a 1000-1100 nm infrared light beam. The light beam is reflected by the second cavity mirror (9) to the third cavity mirror (10), and then folded back along the original path by the third cavity mirror (10). The light beam is then reflected by the second cavity mirror (9) and the first cavity mirror (4), and then folded back along the original path at the fourth cavity mirror (17). The light beam folded back by the fourth cavity mirror (17) is then reflected by the first cavity mirror (4), completing the first loop. The 1000-1100 nm light beam in the first loop will produce a nonlinear effect when passing through the first frequency doubling crystal (16), generating a 500-550 nm light beam, which will be folded back along the original path through the fourth cavity mirror (17), reflected by the first optical splitter (14) to the fifth cavity mirror (20), and then reflected by the fifth cavity mirror (20) to the inside of the second frequency doubling crystal (25) for transformation, and the remaining 500-550 nm light beam will be folded back along the original path through the sixth cavity mirror (27), pass through the second frequency doubling crystal (25) again, and then pass through the fifth cavity mirror (20), reflected by the first optical splitter (14), and then reach the fourth cavity mirror (17), thus completing the second loop; The side of the first cavity mirror (4) close to the gain medium (5) or the first optical splitter (14) is coated with a 1000-1100nm high reflection film, the side of the second cavity mirror (9) close to the Q-switching element (7) or the third cavity mirror (10) is coated with a 1000-1100nm high reflection film, the side of the third cavity mirror (10) close to the second cavity mirror (9) is coated with a 1000-1100nm high reflection film, the side of the fourth cavity mirror (17) close to the first optical splitter (14) is coated with a 1000-1100nm, 5 00-550nm high reflection film, the first light splitting device (14) is also coated with a 500-550nm high reflection film on a side close to the fourth cavity mirror (17), the fifth cavity mirror (20) is coated with a 500-550nm high reflection film on a side close to the second focusing lens (23), the sixth cavity mirror (27) is coated with a 500-550nm high reflection film on a side close to the second collimating lens (26), and the second light splitting device (28) is coated with a 250-275nm high reflection film on a side close to the sixth cavity mirror (27); The third cavity mirror (10) is fixed on the displacement motor (12), and the position of the displacement motor (12) is moved to drive the third cavity mirror (10) to move in the second direction.

2. The ultraviolet laser according to claim 1, characterized in that The first cavity mirror (4) is placed at 60 degrees to the light paths in the first direction and the third direction, the second cavity mirror (9) is placed at 45 degrees to the light paths in the first direction and the second direction, the second spectrometer (28) is placed at 45 degrees to the light paths in the fifth direction and the sixth direction, the fifth cavity mirror (20) is placed at 45 degrees to the light path in the fourth direction, and the fifth cavity mirror (20) is located on a side close to the third cavity mirror (10), the devices in the second direction and the third direction are both arranged on the same side of the first direction, and the device in the fifth direction is arranged on a side of the fifth cavity mirror (20) away from the first direction.

3. The ultraviolet laser according to claim 1, characterized in that The front and rear end faces of the first collimating lens (2), the first focusing lens (3), the first cavity mirror (4), the gain medium (5) and the Q-switched element (7) are all coated with 808 / 880nm anti-reflection films, the double sides of the second focusing lens (23) are coated with 500-550nm anti-reflection films, the side of the second focusing lens (23) close to the second frequency doubling crystal (25) is coated with 250-275nm high-reflection films, and the double sides of the second collimating lens (26) are coated with 500-550nm and 250-275nm anti-reflection films.

4. The ultraviolet laser according to claim 1, characterized in that The front and rear end faces of the gain medium (5), the Q-switching element (7) and the first optical splitter (14) are all coated with 1000-1100nm anti-reflection films, the double sides of the first frequency-doubling crystal (16) are both coated with 1000-1100nm and 500-550nm anti-reflection films, and the double sides of the second frequency-doubling crystal (25) are both coated with 250-275nm and 500-550nm anti-reflection films.

5. The ultraviolet laser according to claim 1, characterized in that , a third optical splitter (30) is also included in the sixth direction, and the third optical splitter (30) is located behind the second optical splitter (28) in the sixth direction.

6. The ultraviolet laser according to claim 5, characterized in that The third optical splitter (30) is coated with a 500-550nm high-reflection film on one side close to the second optical splitter (28), and is coated with a 250-275nm anti-reflection film on both sides.

7. The ultraviolet laser according to claim 5, characterized in that The first frequency doubling crystal (16) is externally provided with a first temperature control module (15), and the second frequency doubling crystal (25) is externally provided with a second temperature control module (24).

8. The ultraviolet laser according to claim 1, wherein: Both sides of the first cavity mirror (4) are coated with a 500-550nm anti-reflection film, both sides of the second cavity mirror (9) and the third cavity mirror (10) are coated with an 808 / 880nm anti-reflection film, both sides of the fifth cavity mirror (20) are coated with a 1000-1100nm anti-reflection film, and both sides of the second spectrometer (28) are coated with a 500-550nm anti-reflection film.

9. The ultraviolet laser according to claim 7, wherein: Also includes: a first pinhole stop (6), a second pinhole stop (8), a third pinhole stop (13), and a fourth pinhole stop (19); The first pinhole diaphragm (6) is located between the gain medium (5) and the Q-switching element (7), the second pinhole diaphragm (8) is located between the Q-switching element (7) and the second cavity mirror (9), the third pinhole diaphragm (13) is located between the first cavity mirror (4) and the first spectrometer (14), and the fourth pinhole diaphragm (19) is located between the first spectrometer (14) and the fifth cavity mirror (20).

10. The ultraviolet laser according to claim 9, wherein: Also includes: a first idle light collector (11), a second idle light collector (18), a third idle light collector (22), and a fourth idle light collector (29); The first idle light collector (11) is located on a side of the second cavity mirror (9) away from the Q-switching element (7) in a first direction, the second idle light collector (18) is located on a side of the first cavity mirror (4) away from the first optical splitter (14) in a third direction, the third idle light collector (22) is located on a side of the first cavity mirror (4) away from the first optical splitter (14) in a fourth direction, and the fourth idle light collector (29) is located on a side of the second optical splitter (28) away from the sixth cavity mirror (27) in a fifth direction.

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