CN218976013U - Ultraviolet laser - Google Patents

Abstract

The application provides an ultraviolet laser which sequentially comprises a pumping source, a collimating lens, a focusing lens, a first cavity mirror, a gain medium, a Q-switching element and a second cavity mirror in a first direction; the second direction sequentially comprises a third cavity mirror and a displacement motor; the third direction sequentially comprises a first light-splitting device, a frequency doubling crystal and a fourth cavity mirror; a fifth endoscope is also included in the fourth 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 arranged in the fifth direction. According to the ultraviolet laser, the third cavity mirror is driven to move in the second direction through the position of the movable displacement motor, so that the cavity length can be adjusted, the cavity length suitable for corresponding power output is obtained under different output powers, and the ultraviolet laser with the advantages of precise and adjustable cavity length, compatibility of multiple high-low power overlapping stable output, high integration and compact structure is obtained.

Description

Ultraviolet laser

Technical Field

The utility model relates to the technical field of lasers, in particular to an ultraviolet laser with adjustable cavity length and high stability.

Background

In recent years, with the increasingly vigorous demands of new energy industries, higher requirements are put on front-end laser processing technology. The effect of laser stability on laser light is enormous, especially when the laser is used in precision machining, the effect of cavity length on laser stability is particularly critical, and we know that the stability conditions of the resonant cavity are: 0< (1-L/R1) (1-L/R2) <1. The curvatures R1 and R2 of the laser cavity mirror are generally specific in practical use, and the cavity length L can be controlled to greatly improve the practical use effect for the laser. The influence of a thermal lens of a high-power solid laser is not negligible in the actual working process, the traditional solid laser can achieve stable laser output under a certain specific state, and one laser can not meet the requirement when an application end needs to use high-power and low-power overlapped light emitting operation, or can not be compatible when the application end needs to use lasers with different powers for operation. The ultraviolet laser has a shorter wavelength than infrared and larger photon energy, so that the ultraviolet laser can be precisely processed in a finer field and is popular with society, and the stability of the ultraviolet laser directly determines the yield of the precise processing.

Based on the above, it is necessary to invent an ultraviolet laser capable of obtaining an ultraviolet laser output with adjustable cavity length, high stability and compact structure.

Disclosure of Invention

The present application is directed to an ultraviolet laser, so as to solve the problems set forth in the background art.

In order to achieve the above purpose, the present application provides the following technical solutions:

the application provides an ultraviolet laser which can obtain the technical effects of adjustable cavity length, high stability and compact structure of ultraviolet laser output. The ultraviolet laser sequentially comprises a pumping 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 a first direction; the second direction sequentially comprises a third cavity mirror and a displacement motor; the third direction sequentially comprises a first light-splitting device, a first frequency doubling crystal and a fourth cavity mirror; the third cavity mirror is positioned behind the second cavity mirror in the second direction, and the first light splitting device is positioned behind the first cavity mirror in the third direction. The fourth direction also comprises a fifth cavity mirror, the fifth cavity mirror is positioned behind the first light splitting device in the fourth direction and is placed at 45 degrees with the light path in the fourth direction, and the fifth cavity mirror is positioned at one side close to the third cavity mirror. The second focusing lens is positioned behind the fifth cavity mirror in the fifth direction.

The pumping source is generally a semiconductor laser, and emits infrared light beams with the wavelength of 808nm/880nm, and after the infrared light beams are output through an optical fiber jumper, the light beams collimated by the first collimating lens are converged by the first focusing lens when passing through the first focusing lens, so that the light beams are focused in the gain medium after passing through the first cavity mirror. The pump source, the optical fiber jumper, the first collimating lens and the first focusing lens form a pump coupling module of the ultraviolet laser.

The Q-switched element may control the power pulses required for the forming operation.

The first cavity mirror, the second cavity mirror, the third cavity mirror, the fourth cavity mirror, the first light splitting device, the fifth cavity mirror and the sixth cavity mirror jointly form a resonant module, namely a resonant cavity, of the ultraviolet laser.

The resonance principle of the ultraviolet laser is as follows: the pumping light passing through the first cavity mirror generates stimulated radiation in the gain medium to generate 1000-1100nm infrared light beams, and reflecting films are plated on the corresponding sides of the cavities of the first cavity mirror, the second cavity mirror, the third cavity mirror and the fourth cavity mirror. The 1000-1100nm infrared beam is returned to the first cavity mirror through the second cavity mirror, the third cavity mirror and the fourth cavity mirror, and is continuously reflected to form a first loop. When the pump source is continuously excited, the 1000-1100nm infrared photons continuously resonate in the loop.

The 1000-1100nm beam in the first loop may have a nonlinear effect when passing through the first frequency doubling crystal, resulting in a 500-550nm beam. The light beam is turned back through the original path of the fourth cavity mirror, is reflected to the fifth cavity mirror by the first light splitting device, is reflected to the inside of the second frequency doubling crystal by the fifth cavity mirror to be converted, and the residual 500-550nm light beam is turned back through the original path of the sixth cavity mirror, passes through the second frequency doubling crystal again and then sequentially passes through the fifth cavity mirror, and reaches the fourth cavity mirror after being reflected by the first light splitting device, so that the second loop is completed.

The 500-550nm green light beam output by the first light-splitting device is reflected by the fifth cavity mirror, and then is converged by the second focusing lens when passing through the second focusing lens, so that the green light beam is focused in the second frequency doubling crystal, and the light beam collimated by the second collimating lens is reflected by the sixth cavity mirror. Finally, the 250-275nm ultraviolet laser is finally and efficiently and stably output to the sixth direction through the 250-275nm high-reflection film of the second light splitting device.

In order to match different powers generated by the ultraviolet laser, the adverse effect on the stability of the resonant cavity caused by the thermal lens under different powers is eliminated, the ultraviolet laser output with high stability is obtained, the third cavity mirror is fixed on the displacement motor, and the third cavity mirror is driven to move in the second direction by moving the position of the displacement motor, so that the cavity length is adjustable. Meanwhile, the third cavity mirror moves in the second direction, so that the light path direction of the whole ultraviolet laser cannot be changed when the cavity length is regulated, and the stability of ultraviolet laser output is ensured.

According to the ultraviolet laser, the resonant cavity with two loops and compact structure is designed, the position of the movable displacement motor is used for driving the third cavity mirror to move in the second direction, so that the cavity length can be adjusted, the cavity length of the adaptive power output can be obtained through adjusting the cavity length, the output power can be stable and continuous, and the ultraviolet laser with the advantages of precise and adjustable cavity length, compatibility of multiple high-low power overlapping stable output, high integration and compact structure is obtained.

Drawings

For a clearer description of embodiments of the present application or of the prior art, the drawings that are used in the description of the embodiments or of the prior art will be briefly described, it being apparent that the drawings in the description that follow are only some embodiments of the present application, and that other drawings may be obtained from these drawings by a person of ordinary skill in the art without inventive effort.

Fig. 1 is a schematic diagram of a first structure of an ultraviolet laser provided in the present application;

fig. 2 is a schematic diagram of a second structure of the ultraviolet laser provided in the present application;

fig. 3 is a schematic diagram of a third structure of the ultraviolet laser provided in the present application;

fig. 4 is a schematic diagram of a fourth structure of the ultraviolet laser provided in the present application;

fig. 5 is a schematic view of a fifth structure of the ultraviolet laser provided in the present application.

Reference numerals: 1. the device comprises a pumping source, 2, a first collimating lens, 3, a first focusing lens, 4, a first cavity mirror, 5, a gain medium, 6, a first small hole diaphragm, 7, a Q-switching element, 8, a second small hole diaphragm, 9, a second cavity mirror, 10, a third cavity mirror, 11, a first idle frequency light collector, 12, a displacement motor, 13, a third small hole diaphragm, 14, a first light splitting device, 15, a first temperature control module, 16, a first frequency doubling crystal, 17, a fourth cavity mirror, 18, a second idle frequency light collector, 19, a fourth small hole diaphragm, 20, a fifth cavity mirror, 22, a third idle frequency light collector, 23, a second focusing lens, 24, a second temperature control module, 25, a second frequency doubling crystal, 26, a second collimating lens, 27, a sixth cavity mirror, 28, a second light splitting device, 29, a fourth idle frequency light collector, 30 and a third light splitting device.

Detailed Description

In order to provide a better understanding of the present application, those skilled in the art will now make further details of the present application with reference to the drawings and detailed description. It should be apparent that the described embodiments are only some of the embodiments of the present application and are not intended to limit the scope of the claims of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

Referring to fig. 1, fig. 1 is a schematic diagram of a first structure of an ultraviolet laser provided in the present application, where the ultraviolet laser 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-switched element 7, and a second cavity mirror 9 in sequence in a first direction; the second direction comprises a third cavity mirror 10 and a displacement motor 12 in sequence, wherein the third cavity mirror 10 is positioned behind the second cavity mirror 9 in the second direction. The third direction sequentially comprises a first light-splitting device 14, a first frequency doubling crystal 16 and a fourth cavity mirror 17, wherein the first light-splitting device 14 is positioned behind the first cavity mirror 4 in the third direction. The fourth direction further includes a fifth cavity mirror 20, where the fifth cavity mirror 20 is located at the rear of the first beam splitter 14 in the fourth direction and is placed at 45 ° to the optical path in the fourth direction, and the fifth cavity mirror 20 is located at a side close to the third cavity mirror 10. 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 arranged in the fifth direction, and the second focusing lens 23 is positioned behind the fifth cavity mirror 20 in the fifth direction. The structure is arranged, so that the ultraviolet laser is a laser with high integration level and compact structure.

The pump source 1 is typically a semiconductor laser, and emits an infrared beam with a wavelength of about 808nm/880nm, and when the infrared beam is output through an optical fiber jumper (not shown in the figure) and then collimated by the first collimating lens 2, the infrared beam passes through the first focusing lens 3, and is converged by the first focusing lens 3, so that the infrared beam is focused in the gain medium 5 after passing through the first cavity mirror 4. I.e. the pump source 1, the optical fiber jumper, the first collimating lens 2 and the first focusing lens 3 together constitute a pump coupling module of the ultraviolet laser of the present application.

The first cavity mirror 4, the second cavity mirror 9, the third cavity mirror 10, the fourth cavity mirror 17, the first light splitting device 14, the fifth cavity mirror 20 and the sixth cavity mirror 27 together form a resonant module, namely a resonant cavity, of the ultraviolet laser.

The resonance principle of the ultraviolet laser is as follows: the pump light passing through the first cavity mirror 4 generates stimulated radiation in the gain medium 5 to generate 1000-1100nm infrared light beams, the light beams are reflected to the third cavity mirror 10 through the second cavity mirror 9 and then turned back by the original path of the third cavity mirror 10, the light beams are reflected through the second cavity mirror 9 and the first cavity mirror 4 and then turned back by the original path at the fourth cavity mirror 17, and the light beams turned back by the fourth cavity mirror 17 are reflected by the first cavity mirror 4, so that the first loop is completed. When the pump source 1 is continuously excited, the 1000-1100nm infrared photons continuously resonate in this loop.

The 1000-1100nm beam in the first loop experiences a nonlinear effect as it passes through the first frequency doubling crystal 16, producing a 500-550nm beam. The light beam is turned back by the original path of the fourth cavity mirror 17, is reflected to the fifth cavity mirror 20 by the first light splitting device 14, is reflected to the inside of the second frequency doubling crystal 25 by the fifth cavity mirror 20 to be converted, the residual 500-550nm light beam is turned back by the original path of the sixth cavity mirror 27, passes through the second frequency doubling crystal 25 again and then sequentially passes through the fifth cavity mirror 20, and reaches the fourth cavity mirror 17 after being reflected by the first light splitting device 14, so that the second loop is completed. Namely, the first cavity mirror 4, the second cavity mirror 9, the third cavity mirror 10, the fourth cavity mirror 17, the first light splitting device 14, the fifth cavity mirror 20 and the sixth cavity mirror 27 jointly form a resonant cavity of two resonant circuits, and the first light splitting device 14 plays a dual role of a dichroic mirror and a cavity mirror in the resonant cavity.

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

In order to ensure the high-efficiency and stable normal operation of the resonant cavity, a side surface of the first cavity mirror 4, which is close to the first light splitting device 14 or the gain medium 5, is plated with a high-reflection film of 1000-1100nm, a side surface of the second cavity mirror 9, which is close to the Q-switching element 7 or the third cavity mirror 10, is plated with a high-reflection film of 1000-1100nm, a side surface of the third cavity mirror 10, which is close to the second cavity mirror 9, is plated with a high-reflection film of 1000-1100nm, 500-550nm, a side surface of the fourth cavity mirror 17, which is close to the first light splitting device 14, is plated with a high-reflection film of 500-550nm, a side surface of the first light splitting device 14, which is close to the fourth cavity mirror 17, is plated with a high-reflection film of 500-550nm, a side surface of the fifth cavity mirror 20, which is close to the second collimating lens 23, is plated with a high-reflection film of 500-550nm, a side surface of the sixth cavity mirror 27, which is close to the second collimating lens 26, is plated with a high-reflection film of 500-550nm, a side surface of the fourth cavity mirror 17, which is plated with a high-reflection film of 500-550nm, a high-reflection film of 275nm, a side surface of the fifth cavity mirror 28, a surface of the high-reflection film of 500-nm is plated on a side surface of the fifth cavity mirror, which is close to the side mirror 27, close to the side mirror is close to the side surface to the mirror 27. The 250-275nm ultraviolet laser light is finally and efficiently and stably output to the sixth direction through the 250-275nm high-reflection film of the second light splitting device 28.

The Q-switching element 7 can control the formation of the required power pulses. In particular embodiments, an acousto-optic Q-switched element may be used.

In order to match the different powers generated by the ultraviolet laser, high-stability ultraviolet laser output is obtained, the third cavity mirror 10 is fixed on the displacement motor 12, and the third cavity mirror 10 is driven to move in the second direction by moving the position of the displacement motor 12, so that the cavity length is adjustable. Meanwhile, the third cavity mirror 10 moves in the second direction, so that the light path direction of the whole ultraviolet laser cannot be changed when the cavity length is adjusted, and the stability of ultraviolet laser output is ensured. The displacement motor 12 is a precision displacement motor, and the displacement motor 12 can be controlled to move through software.

In a preferred scheme, the first cavity mirror 4 is placed at an angle of 60 degrees to the light paths in the first direction and the third direction, the second cavity mirror 9 is placed at an angle of 45 degrees to the light paths in the first direction and the second direction, and the second light splitting device 28 is placed at an angle of 45 degrees to the light paths in the fifth direction and the sixth direction. The device in the second direction and the device in the third direction are all set up in the same side of first direction, the device in the fifth direction sets up in the one side that the first direction was kept away from to fifth chamber mirror 20, above structure setting can make this application ultraviolet laser is high integrated level, compact structure's laser, simultaneously, when adjusting the chamber length, can not change the light path direction of whole ultraviolet laser, guarantees ultraviolet laser output's stability.

Further, in order to reduce the energy loss of the light beam and improve the overall light transmittance, 808/880nm antireflection films are coated on the front end face and the rear end face of the first collimating lens 2, the first focusing lens 3, the first cavity mirror 4, the gain medium 5 and the Q-switching element 7, 500-550nm antireflection films are coated on the two sides of the second focusing lens 23, 250-275nm high reflection films are coated on one side of the second focusing lens 23, which is close to the second frequency doubling crystal 25, and 500-550nm and 250-275nm antireflection films are coated on the two sides of the second collimating lens 26.

Further, in order to fully and effectively utilize the light beams, the front end face and the rear end face of the gain medium 5, the Q-switching element 7 and the first light splitting device 14 are coated with 1000-1100nm antireflection films, the two sides of the first frequency doubling crystal 16 are coated with 1000-1100nm and 500-550nm antireflection films, and the two sides of the second frequency doubling crystal 25 are coated with 250-275nm and 500-550nm antireflection films.

Further, in order to improve the stability of the overall operation of the device, the gain medium 5 is further provided with a heat sink structure, and the heat sink structure timely conducts out the redundant heat on the gain medium 5.

Further, referring to fig. 2, fig. 2 is a schematic diagram of a second structure of the ultraviolet laser provided in the present application, so as to make 250-275nm ultraviolet output more efficiently and stably, and obtain purer 250-275nm ultraviolet laser. A third light splitting device 30 is further included in the sixth direction, and the third light splitting device 30 is located behind the second light splitting device 28 in the sixth direction. The third light-splitting device 30 is coated with a 500-550nm high-reflection film on one side close to the second light-splitting device 28, and is coated with 250-275nm anti-reflection films on both sides.

Further, in order to reduce interference of idler light on resonance, two sides of the first cavity mirror 4 are coated with 500-550nm antireflection films, two sides of the second cavity mirror 9 and the third cavity mirror 10 are coated with 808/880nm and 500-550nm antireflection films, two sides of the fifth cavity mirror 20 are coated with 1000-1100nm antireflection films, and two sides of the second light splitting device 28 are coated with 500-550nm antireflection films.

Further, referring to fig. 3, fig. 3 is a schematic diagram of a third structure of the ultraviolet laser provided in the present application, a first temperature control module 15 is sleeved outside the first frequency doubling crystal 16, and the first temperature control module 15 provides a stable temperature environment for the first frequency doubling crystal 16; the second temperature control module 24 is further sleeved outside the second frequency doubling crystal 25, and the second temperature control module 24 provides a stable temperature environment for the second frequency doubling crystal 25, so that the stability of the whole operation of the device is improved.

Further, referring to fig. 4, fig. 4 is a schematic diagram of a fourth structure of the uv laser provided in the present application. The ultraviolet laser, on the basis of the ultraviolet laser shown in fig. 3, may further include: a first aperture stop 6, a second aperture stop 8, a third aperture stop 13, a fourth aperture stop 19. The first aperture diaphragm 6 is positioned between the gain medium 5 and the Q-switching element 7, and can play a role in limiting modes and blocking stray light on a non-axis to improve the light path stability of the whole system; the second aperture diaphragm 8 is located between the Q-switching element 7 and the second cavity mirror 9, and can filter out diffracted light after passing through the Q-switching element 7; the third aperture diaphragm 13 is located between the first cavity mirror 4 and the first light splitting device 14, and can also play roles in limiting modes and blocking stray light on a non-axis to improve the light path stability of the whole system; the fourth aperture stop 19 is located between the first beam splitter 14 and the fifth cavity mirror 20, and can limit the output of the green laser, so as to improve the quality of the output green laser.

Further, referring to fig. 5, fig. 5 is a schematic view of a fifth structure of the ultraviolet laser provided in the present application. To reduce interference of idler light on resonance operation, a stable ultraviolet laser output is obtained, and the ultraviolet laser further comprises, based on the ultraviolet laser shown in fig. 4: a first idler collector 11, a second idler collector 18, a third idler collector 22, a fourth idler collector 29; the first idler light collector 11 is positioned on one side of the second cavity mirror 9 away from the Q-switching element 7 in the first direction and is mainly used for collecting 808/880nm and 500-550nm idler light; the second idler light collector 18 is positioned at one side of the first cavity mirror 4, which is far away from the first light splitting device 14 in the third direction, and mainly collects 500-550nm idler light; the third idler collector 22 is positioned at one side of the fifth cavity mirror 20, which is far away from the first light splitting device 14 in the fourth direction, and mainly collects 1000-1100nm idler light; the fourth idler collector 29 is located at a side of the second light splitting device 28 away from the sixth cavity mirror 27 in the fifth direction, and mainly collects 500-550nm idler light. The first idler collector 11, the second idler collector 18, the third idler collector 22 and the fourth idler collector 29 are all used for absorbing and radiating residual fundamental frequency signal light, and the residual fundamental frequency signal light and incompletely reflected frequency doubling light passing through the devices are annihilated in the idler collectors, so that the system stability and the purity of the output ultraviolet laser are improved.

It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is inherent to. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or device that comprises the element. In addition, the parts of the above technical solutions provided in the embodiments of the present application, which are consistent with the implementation principles of the corresponding technical solutions in the prior art, are not described in detail, so that redundant descriptions are avoided.

Specific examples are set forth herein to illustrate the principles and embodiments of the present application, and the description of the examples above is only intended to assist in understanding the methods of the present application and their core ideas. It should be noted that it will be apparent to those skilled in the art that various improvements and modifications can be made to the present application and the various embodiments in the present application can be combined without departing from the principles of the present application, and such improvements, modifications and combinations also fall within the scope of the claims of the present application.

Claims (10)

1. The ultraviolet laser is characterized by sequentially comprising a pumping 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 a first direction;

the device comprises a third cavity mirror (10) and a displacement motor (12) in sequence in a second direction, wherein the third cavity mirror (10) is positioned behind the second cavity mirror (9) in the second direction;

the device comprises a first light-splitting device (14), a first frequency doubling crystal (16) and a fourth cavity mirror (17) in sequence in a third direction, wherein the first light-splitting device (14) is positioned behind the first cavity mirror (4) in the third direction;

the fourth direction also comprises a fifth cavity mirror (20), and the fifth cavity mirror (20) is positioned behind the first light-splitting device (14) in the fourth direction;

the device comprises a second focusing lens (23), a second frequency doubling crystal (25), a second collimating lens (26), a sixth cavity mirror (27) and a second light splitting device (28) in sequence in a fifth direction, wherein the second focusing lens (23) is positioned at the rear of the fifth cavity mirror (20) in the fifth direction;

the pumping source (1) is a semiconductor laser, and emits 808nm/880nm infrared light beams, the infrared light beams are output through optical fiber jumpers, and when the light beams collimated through the first collimating lens (2) pass through the first focusing lens (3), the light beams are converged by the first focusing lens (3) so as to be focused in the gain medium (5) after passing through the first cavity mirror (4);

the pump light passing through the first cavity mirror (4) generates stimulated radiation in the gain medium (5) to generate 1000-1100nm infrared light beams, the light beams are reflected to the third cavity mirror (10) through the second cavity mirror (9) and then turned back by the original path of the third cavity mirror (10), then the light beams reflected by the second cavity mirror (9) and the first cavity mirror (4) are turned back by the original path at the fourth cavity mirror (17), and the light beams turned back by the fourth cavity mirror (17) are reflected by the first cavity mirror (4) to complete the first loop;

the 1000-1100nm light beam in the first loop can generate nonlinear effect when passing through the first frequency doubling crystal (16), 500-550nm light beam is generated, the light beam is turned back by the original path of the fourth cavity mirror (17), is reflected to the fifth cavity mirror (20) by the first light splitting device (14), is reflected to the inside of the second frequency doubling crystal (25) by the fifth cavity mirror (20) to be converted, the residual 500-550nm light beam is turned back by the original path of the sixth cavity mirror (27), passes through the second frequency doubling crystal (25) again and then sequentially passes through the fifth cavity mirror (20), and the first light splitting device (14) is reflected and then reaches the fourth cavity mirror (17), so as to finish the second loop;

a side surface of the first cavity mirror (4) close to the gain medium (5) or the first light splitting device (14) is plated with a 1000-1100nm high reflection film, a side surface of the second cavity mirror (9) close to the Q-switching element (7) or the third cavity mirror (10) is plated with a 1000-1100nm high reflection film, a side surface of the third cavity mirror (10) close to the second cavity mirror (9) is plated with a 1000-1100nm high reflection film, a side surface of the fourth cavity mirror (17) close to the first light splitting device (14) is plated with a 1000-1100nm high reflection film and a 500-550nm high reflection film, a side surface of the first light splitting device (14) close to the fourth cavity mirror (17) is also plated with a 500-550nm high reflection film, a side surface of the fifth cavity mirror (20) close to the second focusing lens (23) is plated with a 500-550nm high reflection film, a side surface of the sixth cavity mirror (27) close to the second collimating lens (26) is plated with a 500-550nm high reflection film, and a side surface of the sixth cavity mirror (27) close to the second collimating lens (27) is plated with a 500-550nm high reflection film;

the third cavity mirror (10) is fixed on the displacement motor (12), and the third cavity mirror (10) is driven to move in the second direction by moving the position of the displacement motor (12).

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

3. The ultraviolet laser according to claim 1, wherein the front and rear end surfaces of the first collimating lens (2), the first focusing lens (3), the first cavity mirror (4), the gain medium (5) and the Q-switching element (7) are coated with 808/880nm antireflection films, the two sides of the second focusing lens (23) are coated with 500-550nm antireflection films, one 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 two sides of the second collimating lens (26) are coated with 500-550nm and 250-275nm antireflection films.

4. The ultraviolet laser according to claim 1, wherein the front and rear end surfaces of the gain medium (5), the Q-switching element (7) and the first spectroscopic device (14) are coated with 1000-1100nm antireflection films, the two sides of the first frequency doubling crystal (16) are coated with 1000-1100nm and 500-550nm antireflection films, and the two sides of the second frequency doubling crystal (25) are coated with 250-275nm and 500-550nm antireflection films.

5. The ultraviolet laser according to claim 1, further comprising a third light splitting device (30) in a sixth direction, the third light splitting device (30) being located behind the second light splitting device (28) in the sixth direction.

6. The ultraviolet laser according to claim 5, wherein the third light splitting device (30) is coated with a 500-550nm high reflection film on a side close to the second light splitting device (28), and is coated with a 250-275nm antireflection film on both sides.

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

8. The ultraviolet laser according to claim 1, wherein the two sides of the first cavity mirror (4) are coated with 500-550nm antireflection films, the two sides of the second cavity mirror (9) and the third cavity mirror (10) are coated with 808/880nm antireflection films, the two sides of the fifth cavity mirror (20) are coated with 1000-1100nm antireflection films, and the two sides of the second light splitting device (28) are coated with 500-550nm antireflection films.

9. The ultraviolet laser as set forth in claim 7, further comprising: the first small aperture diaphragm (6), the second small aperture diaphragm (8), the third small aperture diaphragm (13) and the fourth small aperture diaphragm (19);

the first aperture diaphragm (6) is located between the gain medium (5) and the Q-switching element (7), the second aperture diaphragm (8) is located between the Q-switching element (7) and the second cavity mirror (9), the third aperture diaphragm (13) is located between the first cavity mirror (4) and the first light splitting device (14), and the fourth aperture diaphragm (19) is located between the first light splitting device (14) and the fifth cavity mirror (20).

10. The ultraviolet laser as set forth in claim 9, further comprising: a first idler collector (11), a second idler collector (18), a third idler collector (22), a fourth idler collector (29);

the first idler light collector (11) is located on one side, away from the Q-switching element (7) in the first direction, of the second cavity mirror (9), the second idler light collector (18) is located on one side, away from the first light splitting device (14) in the third direction, of the first cavity mirror (4), the third idler light collector (22) is located on one side, away from the first light splitting device (14) in the fourth direction, of the first cavity mirror (4), and the fourth idler light collector (29) is located on one side, away from the sixth cavity mirror (27) in the fifth direction, of the second light splitting device (28).

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