Detection Device and Method for Laser Thermal Lens Effect of Optical Crystal

Abstract

The present invention discloses a detection device and method for the laser thermal lens effect of an optical crystal, which relates to the field of thermal lens effect detection and includes a pump laser, a probing red laser, and a power detector. Along the beam direction of the pump laser, a beam combiner, a crystal sample stage, and a beam splitter are sequentially arranged. A front reflecting mirror is arranged in the beam direction of the probing red laser, and the front reflecting mirror is used to reflect the beam of the probing red laser towards the beam combiner, so that the beam of the probing red laser coincides with the beam of the pump laser and passes through the optical crystal. A rear reflecting mirror is arranged corresponding to the power detector. The present invention makes the pump laser and the probing light coincide and pass through the optical crystal. By heating the optical crystal with the pump laser, the thermal lens effect of the optical crystal is induced and amplified, and then the probing light is detected, so as to clearly judge the strength of the thermal lens effect of the optical crystal, which is beneficial to the grading of the crystal quality and the improvement of the production process.

Description

Technical Field

[0001] The present invention relates to the field of detection of the thermal lens effect, and particularly to a detection device and method for the laser thermal lens effect of an optical crystal. Background Art

[0002] The laser thermal lens effect of an optical crystal is caused by the absorption of the laser by the crystal itself, resulting in an uneven distribution inside the crystal, thereby causing phenomena such as a decline in the beam quality and instability of the laser output power. Detecting the thermal lens effect of the optical crystal can help the crystal manufacturer evaluate the light absorption characteristics of the crystal, which is beneficial to the classification of the crystal quality and the improvement of the production process.

[0003] There are various existing methods for detecting the laser thermal lens effect of a crystal. Basically, a laser beam is directly applied to the optical crystal, and the intensity of the lens effect is low, resulting in insufficiently obvious detection data and a lack of induction of the intensity of the thermal lens effect. Summary of the Invention

[0004] In order to make up for the deficiencies of the existing technical problems, the purpose of the present invention is to provide a detection device and method for the laser thermal lens effect of an optical crystal, which is used to solve the problem that the existing detection method for the thermal lens effect of a crystal lacks the induction of the intensity of the thermal lens effect, resulting in insufficiently obvious detection data feedback.

[0005] In order to solve the existing technical problems, the technical solution of the present invention is as follows:

[0006] A detection device for the laser thermal lens effect of an optical crystal includes: a pump laser, a probe red laser, and a power detector. A beam combining mirror, a crystal sample stage, and a beam splitting mirror are sequentially arranged along the beam direction of the pump laser. The crystal sample stage is used to position the optical crystal. A front reflecting mirror is arranged in the beam direction of the probe red laser, and the front reflecting mirror is used to reflect the beam of the probe red laser towards the beam combining mirror, so that the beam of the probe red laser coincides with the beam of the pump laser and passes through the optical crystal. A rear reflecting mirror is arranged corresponding to the power detector, and the beam of the probe red laser is reflected by the beam splitting mirror and the rear reflecting mirror in sequence and then guided to the power detector.

[0007] Preferably, a beam trash can is arranged corresponding to the beam splitting mirror, and the beam of the pump laser passes through the beam splitting mirror and is guided to the beam trash can.

[0008] Preferably, it further includes an angle adjuster, which includes an integrated box. Four groups of belt assemblies are arranged in the integrated box. The front mirror, beam combiner, beam splitter, and rear mirror are all correspondingly driven and connected to the belt assemblies through belts. A driving rod is inserted and removed along the arrangement direction of the belt assemblies in the integrated box. The insertion and removal displacement of the driving rod can engage with one of the four groups of belt assemblies, and rotating the driving rod can selectively drive and adjust the angles of the front mirror, beam combiner, beam splitter, and rear mirror.

[0009] Preferably, each belt assembly includes a driving pulley. The front mirror, beam combiner, beam splitter, and rear mirror are all rotatably installed on the surface of the bracket through damping bearings. The front mirror, beam combiner, beam splitter, and rear mirror are all coaxially fixed with driven pulleys. The driven pulleys are connected to the driving pulley through belts. The driving pulley is coaxially fixed with a driven gear, and the driven gear is meshed with a driving gear. The driving rod can be selectively meshed and connected with the driving gear.

[0010] Preferably, a tension pulley is arranged opposite to the driving pulley. The belt outside the driving pulley bypasses the tension pulley. The tension pulley is swingably connected to the integrated box through a swing frame. A stud is rotatably connected to the surface of the swing frame. The integrated box has a through hole on its surface. The stud penetrates through the through hole to the outside of the integrated box. A nut is threadedly connected to the surface of the stud. The nut abuts against the outer wall of the integrated box to pull the swing frame outwards, so that the tension pulley tightens the belt.

[0011] Preferably, the driving rod includes a rod body. The surface of the integrated box has a shaft cylinder. The rod body is linearly slid into the integrated box through the shaft cylinder. A plurality of pressing plates are rotatably arranged around the outer end of the rod body. The inner edge of the pressing plate inclines towards the inner end of the rod body. A plurality of fins are elastically rotatably arranged around the inner end of the rod body through torsion springs. The inner edge of the fin inclines towards the outer end of the rod body. A shaft rod is axially slid in the rod body. The shaft rod is connected with a spring that presses towards the outer end of the rod body. The two ends of the shaft rod are respectively fixed with a rear sphere and a front sphere. The rear sphere abuts against the inner edge of the pressing plate, and the front sphere abuts against the inner edge of the fin. By pressing the pressing plate to abut against the rear sphere and the front sphere to move, the front sphere squeezes the fin to rotate and protrude from the surface of the rod body.

[0012] Preferably, a plurality of toothed plates are elastically rotatably arranged in the integrated box through torsion springs. The toothed plates straddle the driving rod and are correspondingly clamped with the driving gears one by one. When the fin protrudes from the surface of the rod body and is clamped with the driving gear, the fin pushes the toothed plate to rotate and disengage from the clamping with the driving gear.

[0013] Preferably, the part where the toothed plate is clamped with the driving gear is an arc-shaped tooth surface, and the part where the toothed plate straddles the driving rod is a smooth plate surface.

[0014] Preferably, a telescopic groove is formed in the inner wall of the shaft cylinder, and a ball is elastically slid in the telescopic groove through a spring. A plurality of annular grooves are arranged on the surface of the rod body, and the ball can be clamped into the annular groove. The distance between the annular grooves is the same as the distance between the belt assemblies arranged.

[0015] A method for detecting the optical crystal laser thermal lens effect based on the optical crystal laser thermal lens effect detection device is as follows:

[0016] A. Beam debugging: Turn on the pump laser and the detection red laser. The beam of the pump laser sequentially passes through the beam combiner, the optical crystal, and the beam splitter. The beam of the detection red laser is reflected by the front mirror and the beam combiner and passes through the optical crystal, and then is reflected by the beam splitter and the rear mirror to the power detector. Coordinate and rotate the reflection angles of the front mirror, the beam combiner, the beam splitter, and the rear mirror to make the beams of the pump laser and the detection red laser coincide and pass through the optical crystal, and ensure that the beam of the detection red laser is accurately guided to the power detector.

[0017] B. Background noise acquisition: Turn off the detection red laser and turn on the pump laser, and sequentially increase the beam power of the pump laser to obtain the background noise of the power detector.

[0018] C. Variable power signal acquisition: Turn on the pump laser and the detection red laser. The beam of the pump laser heats the optical crystal. The beam of the detection red laser passes through the optical crystal and then the central light intensity of the diffraction spot is detected by the power detector. Then, the beam power of the pump laser is increased in a gradient, and the beam of the detection red laser is detected multiple times, so as to obtain the trend line of the central light intensity of the diffraction spot changing with the pump power, and the intensity of the thermal lens effect of the optical crystal is fed back through the slope of the trend line.

[0019] Compared with the prior art, the advantages of the present invention are as follows:

[0020] 1. In the present invention, the pump laser and the detection light coincide and pass through the optical crystal. The optical crystal is heated by the pump laser to induce the amplification of the thermal lens effect of the optical crystal, and then the detection light is detected, so that the strength of the thermal lens effect of the optical crystal can be clearly judged, which is beneficial to the grading of the crystal quality and the improvement of the production process.

[0021] 2. In the present invention, the front mirror, the beam combiner, the beam splitter, and the rear mirror are independently adjusted and controlled at a fixed point position by the angle adjuster, which is convenient for observing the beam coincidence degree, has convenient operation, and high operation safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0023] Figure 2This is the schematic diagram of the measurement principle of the thermal lens effect of the present invention.

[0024] Figure 3 This is the schematic diagram of the distribution of the lens torsion drive of the present invention.

[0025] Figure 4 This is the schematic diagram of the structure of the angle adjuster of the present invention.

[0026] Figure 5 This is one of the schematic diagrams of the structure of the belt assembly of the present invention.

[0027] Figure 6 This is the second schematic diagram of the structure of the belt assembly of the present invention.

[0028] Figure 7 This is the schematic diagram of the structure of the drive rod of the present invention.

[0029] Figure 8 This is the schematic diagram of the limit structure of the drive rod of the present invention.

[0030] Figure 9 This is the trend chart of the change of the central light intensity of the diffraction spot of the present invention.

[0031] Reference numerals: 1, pump laser; 2, detection red laser; 3, front mirror; 31, beam combiner; 32, beam splitter; 33, rear mirror; 4, power detector; 5, beam trash can; 6, crystal sample stage; 7, angle adjuster; 71, integrated box; 72, driving pulley; 73, driven gear; 74, driving gear; 75, toothed plate; 76, tension pulley; 77, swing frame; 78, stud; 79, through port; 710, shaft cylinder; 8, driven pulley; 9, drive rod; 91, rod body; 92, fin; 93, pressing plate; 94, shaft rod; 95, rear sphere; 96, front sphere; 97, annular groove; 98, ball bead; 99, telescopic groove. Detailed implementation manners

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0033] As Figure 1 shown, for the detection device of the laser thermal lens effect of the optical crystal, a rectangular bracket is used as the equipment foundation support, and a pump laser 1, a beam combiner 31, a crystal sample stage 6, a beam splitter 32, and a beam trash can 5 are sequentially and linearly installed along one side of the bracket;

[0034] A detection red laser 2, a front mirror 3, a rear mirror 33, and a power detector 4 are sequentially and linearly installed along the other side of the bracket;

[0035] The beam trash can 5 uses an existing water-cooled beam collector, the pump laser 1 uses an existing 1064nm pump laser device, and the power detector 4 uses a calorimetric power detector.

[0036] The detection method for the laser thermal lens effect of the optical crystal is as follows:

[0037] Beam adjustment: Fix the optical crystal to be measured through the crystal sample stage 6. Turn on the pump laser 1 and the detection red laser 2. The beam of the pump laser 1 sequentially passes through the beam combiner 31, the optical crystal, and the beam splitter 32. The beam of the detection red laser 2 passes through the front reflecting mirror 3 and is reflected by the beam combiner 31 to pass through the optical crystal, and then is reflected by the beam splitter 32 and the rear reflecting mirror 33 to the power detector 4. Coordinate and rotate the reflection angles of the front reflecting mirror 3, the beam combiner 31, the beam splitter 32, and the rear reflecting mirror 33 to make the beams of the pump laser 1 and the detection red laser 2 coincide and pass through the optical crystal, and ensure that the beam of the detection red laser 2 is accurately directed to the power detector 4;

[0038] Background noise acquisition: Turn off the detection red laser 2 and turn on the pump laser 1. Detect the background noise entering the power detector 4. Adjust the power of the pump laser 1 to collect the background noise multiple times. The pump laser powers of the pump laser 1 are 0W, 50W, 100W, 150W, and 200W respectively;

[0039] Variable power signal acquisition: Turn on the pump laser 1 and the detection red laser 2. The beam of the pump laser 1 sequentially passes through the beam combiner 31, the optical crystal, and the beam splitter 32 and is then collected by the beam trash can 5. The pump laser beam of the pump laser 1 heats the optical crystal. The detection red beam of the detection red laser 2 coincides with the pump laser and passes through the optical crystal. The detection red beam is reflected by the beam splitter 32 and the rear reflecting mirror 33 and directed to the power detector 4. Detect the central light intensity of the diffraction spot of the detection red beam through the power detector 4. Adjust the pump laser powers of the pump laser 1 to be 0W, 50W, 100W, 150W, and 200W respectively to detect the beam of the detection red laser 2 multiple times, so as to obtain the trend line of the central light intensity of the diffraction spot changing with the pump power, and feedback the intensity of the thermal lens effect of the optical crystal through the slope of the trend line.

[0040] As Figure 2 shown, the pump laser irradiates the optical crystal in a penetrating manner. Due to light absorption, the crystal generates a temperature rise gradient ∆T(r) in the cross-sectional r direction. The magnitude of the temperature rise is closely related to the light absorption A e of the crystal and the thermophysical parameters (density ρ, specific heat capacity c, thermal diffusivity D, thermal conductivity α), that is:

[0041] ;

[0042] The temperature rise gradient ∆T(r) causes a refractive index gradient to be generated inside the crystal:

[0043] ;

[0044] The refractive index gradient ∆ n ( r ) accumulates over the crystal length d to produce an optical path difference:

[0045] ;

[0046] The optical path difference δ(r) generates a phase difference in the probe laser beam:

[0047] ;

[0048] The phase difference generates a diffraction spot through the diffraction effect during the transmission of the probe laser beam, that is:

[0049] ;

[0050] The stronger the optical absorption of the crystal, the higher the temperature rise, the greater the refractive index gradient, the greater the phase difference, and the more obvious the diffraction spot.

[0051] As Figure 9 shown, in the "I r=0 -P e trend line", the L0 line segment represents the pump laser background noise at different pump laser powers, the L1 line segment represents the central light intensity of the diffraction spot measured for the optical crystal at different pump laser powers, and the L2 line segment represents the actual measurement data of the optical crystal after subtracting the background noise at different pump laser powers;

[0052] Since the temperature rise of the crystal caused by the center of the pump laser beam (r = 0) is the highest, the light intensity I r=0 at the center of the diffraction spot is taken to evaluate the intensity of the crystal thermal lens effect. When the pump laser power increases linearly, I r=0 increases approximately linearly. For any optical crystal, the change trend line of I r=0 with the pump laser power P e can be obtained, that is, the "I r=0 -P e trend line". As Figure 9 shown, in the "I r=0 -P e trend line", the slope K reflects the relative intensity of the crystal thermal lens effect. The smaller the slope K, the smaller the crystal thermal lens effect and the better the crystal quality.

[0053] Keeping the beams of the pump laser 1 and the detection red laser 2 coincide and penetrate through the optical lens is the key to the detection process. During the above beam debugging process, the beams are made to coincide by rotating the front mirror 3, the beam combiner 31, the beam splitter 32, and the rear mirror 33, and the beam of the detection red laser 2 is accurately guided to the power detector 4. Since the beam of the pump laser 1 has the danger of high temperature, the equipment is densely distributed, and it is necessary to maintain an appropriate angle to observe the coincidence effect of the light, it is extremely inconvenient to adjust the front mirror 3, the beam combiner 31, the beam splitter 32, and the rear mirror 33 one by one. In this application, the angle adjuster 7 can independently operate and adjust the angles of the front mirror 3, the beam combiner 31, the beam splitter 32, and the rear mirror 33 at a fixed observation position. The specific operation is as follows:

[0054] As Figures 3 - 6 shown, the angle adjuster 7 is arranged between the front mirror 3 and the rear mirror 33, which is convenient for observing the beam coincidence effect. The angle adjuster 7 includes an integrated box 71. Four groups of belt assemblies are arranged in the integrated box 71. The belt assembly includes a driving pulley 72. The front mirror 3, the beam combiner 31, the beam splitter 32, and the rear mirror 33 are all rotatably installed on the surface of the bracket. The front mirror 3, the beam combiner 31, the beam splitter 32, and the rear mirror 33 are all coaxially fixed with driven pulleys 8. The driven pulleys 8 are connected to the respective driving pulleys 72 through belt drives. The belts between the driven pulleys 8 and the driving pulleys 72 are restricted in their conduction paths by guide pulleys to prevent the belts from winding and contacting each other. The driving pulley 72 is coaxially fixed with a driven gear 73. A driving gear 74 is rotatably installed in the integrated box 71. The driving gear 74 is meshed with the driven gear 73;

[0055] As Figure 7 shown, a driving rod 9 is slidably inserted on one side of the integrated box 71. The sliding direction of the driving rod 9 is parallel to the arrangement direction of the belt assemblies. The driving rod 9 includes a rod body 91. The surface of the integrated box 71 has a shaft cylinder 710. The rod body 91 is linearly slid into the integrated box 71 from the shaft cylinder 710. A plurality of pressing plates 93 are rotatably arranged around the outer end of the rod body 91. The inner edge of the pressing plate 93 is inclined towards the inner end of the rod body 91. A plurality of fins 92 are elastically rotatably arranged around the inner end of the rod body 91 through torsion springs. The inner edge of the fin 92 is inclined towards the outer end of the rod body 91. A shaft rod 94 is axially slid in the rod body 91. The shaft rod 94 is connected with a spring that presses towards the outer end of the rod body 91. The two ends of the shaft rod 94 are respectively fixed with a rear sphere 95 and a front sphere 96. The rear sphere 95 abuts against the inner edge of the pressing plate 93, and the front sphere 96 abuts against the inner edge of the fin 92;

[0056] Under normal conditions, the fin 92 retracts into the rod body 91. Hold the outer end of the rod body 91, and by inserting and pulling the rod body 91, the front end of the rod body 91 is selectively aligned with the driving gear 74. Press the pressing plate 93 with a finger, so that the inner edge of the pressing plate 93 squeezes the rear sphere 95. The rear sphere 95 pushes the shaft rod 94 and the front sphere 96 to move integrally, so that the front sphere 96 squeezes the fin 92 to expand outward against the elastic force. The fin 92 is clamped with the driving gear 74. Rotate the rod body 91 to drive the driving gear 74 to rotate, so that the driven gear 73 drives the driving pulley 72 to rotate. Through the transmission of the belt, the driven pulley 8 drives the front reflecting mirror 3 or the beam combining mirror 31 or the beam splitting mirror 32 or the rear reflecting mirror 33 to rotate and adjust, for controlling the reflection direction of the light beam.

[0057] By controlling the alignment of the fin 92 with different driving gears 74, the angles of the front reflecting mirror 3, the beam combining mirror 31, the beam splitting mirror 32, and the rear reflecting mirror 33 can be independently adjusted.

[0058] The front reflecting mirror 3, the beam combining mirror 31, the beam splitting mirror 32, and the rear reflecting mirror 33 are all rotatably connected to the bracket through damping bearings, so that the front reflecting mirror 3, the beam combining mirror 31, the beam splitting mirror 32, and the rear reflecting mirror 33 have the effect of self-positioning angles.

[0059] As Figure 5 、 6 shown, a tension pulley 76 is arranged for the alignment driving pulley 72. The belt outside the driving pulley 72 bypasses the tension pulley 76. The tension pulley 76 is swingably connected to the integrated box 71 through a swing frame 77. A stud 78 is rotatably connected to the surface of the swing frame 77. The surface of the integrated box 71 has a through port 79. The stud 78 passes through the through port 79 to the outside of the integrated box 71. A nut is threadedly connected to the surface of the stud 78. Rotate the nut to abut against the outer wall of the integrated box 71 to pull the swing frame 77 outward, so that the tension pulley 76 tightens the belt, keeping the belt able to transmit power to drive the driven pulley 8 to rotate and adjust the angle.

[0060] As Figure 5 、 6 shown, a plurality of toothed plates 75 are elastically rotated in the integrated box 71 through torsion springs. The toothed plates 75 straddle the driving rod 9 and are respectively aligned and clamped with the driving gears 74. The part where the toothed plate 75 is clamped with the driving gear 74 is an arc-shaped tooth surface, for locking the angle of the driving gear 74. The part where the toothed plate 75 straddles the driving rod 9 is a smooth plate surface. While the fin 92 protruding from the surface of the rod body 91 is clamped with the driving gear 74, the fin 92 pushes the toothed plate 75 to rotate and disengage from the clamping with the driving gear 74, automatically unlocking the locking of the driving gear 74, facilitating the quick adjustment of the angles of the front reflecting mirror 3, the beam combining mirror 31, the beam splitting mirror 32, and the rear reflecting mirror 33.

[0061] As Figure 8As shown, a telescopic groove 99 is formed in the inner wall of the shaft cylinder 710. A ball 98 is elastically slid in the telescopic groove 99 through a spring. A plurality of annular grooves 97 are arranged on the surface of the rod body 91. The spacing between the annular grooves 97 is the same as the spacing of the belt assembly. During the process of inserting and pulling out the rod body 91, the ball 98 can be caught in the annular groove 97 to position the sliding position of the rod body 91. Through the sense of jerk caused by the elastic clamping of the ball 98 and the annular groove 97, it can be accurately judged whether the rod body 91 is adjusted in place.

[0062] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for detecting the thermal lens effect of an optical crystal laser, using a device for detecting the thermal lens effect of an optical crystal laser, comprising: A pump laser (1), a detection red light laser (2) and a power detector (4), characterized in that a beam combiner (31), a crystal sample stage (6) and a beam splitter (32) are sequentially arranged along the beam direction of the pump laser (1), the crystal sample stage (6) being used to position the optical crystal, a front reflector (3) being arranged in the beam direction of the detection red light laser (2), the front reflector (3) being used to reflect the beam of the detection red light laser (2) in the direction of the beam combiner (31), so that the beam of the detection red light laser (2) overlaps with the beam of the pump laser (1) and passes through the optical crystal, a rear reflector (33) being arranged corresponding to the power detector (4), the beam of the detection red light laser (2) being guided to the power detector (4) after being reflected by the beam splitter (32) and the rear reflector (33) in sequence; The detection steps of optical crystal laser thermal lens effect are as follows: A. Beam debugging: Turn on the pump laser (1) and the detection red light laser (2). The light beam of the pump laser (1) passes through the beam combiner (31), the optical crystal, and the beam splitter (32) in sequence. The light beam of the detection red light laser (2) passes through the front reflector (3) and the beam combiner (31) and passes through the optical crystal. It is then reflected to the power detector (4) by the beam splitter (32) and the rear reflector (33). The reflection angles of the front reflector (3), the beam combiner (31), the beam splitter (32), and the rear reflector (33) are coordinated and rotated so that the light beams of the pump laser (1) and the detection red light laser (2) overlap and pass through the optical crystal, and ensure that the light beam of the detection red light laser (2) is accurately guided to the power detector (4). B. Background noise collection: turn off the detection red light laser (2), turn on the pump laser (1), and increase the beam power of the pump laser (1) in sequence to obtain the background noise of the power detector (4); C. Variable power signal acquisition: Turn on the pump laser (1) and the detection red light laser (2). The light beam of the pump laser (1) heats the optical crystal. After the light beam of the detection red light laser (2) passes through the optical crystal, the light intensity at the center of the diffraction spot is detected by the power detector (4). Then, the power of the beam of the pump laser (1) is increased in a gradient manner. The light beam of the detection red light laser (2) is detected multiple times to obtain a trend line of the light intensity at the center of the diffraction spot changing with the pump power. The slope of the trend line is used to feed back the intensity of the thermal lens effect of the optical crystal.

2. The method for detecting the optical crystal laser thermal lens effect according to claim 1, characterized in that: A light beam trash can (5) is provided corresponding to the beam splitter (32), and the light beam of the pump laser (1) passes through the beam splitter (32) and is guided to the light beam trash can (5).

3. The method for detecting the optical crystal laser thermal lens effect according to claim 1, characterized in that: The invention also comprises an angle adjuster (7), which comprises an integrated box (71), wherein four groups of belt assemblies are arranged in an array in the integrated box (71), wherein the front reflector (3), the beam combining mirror (31), the beam splitter (32), and the rear reflector (33) are all connected to the belt assemblies through belts, and a drive rod (9) is arranged in the integrated box (71) along the arrangement direction of the belt assemblies, wherein the drive rod (9) can be engaged with one of the four groups of belt assemblies by the displacement of the drive rod (9), and the drive rod (9) can be rotated to select one of the four groups of belt assemblies for transmission and adjustment.

4. The method for detecting the optical crystal laser thermal lens effect according to claim 3, characterized in that: The belt assembly comprises a driving pulley (72); the front reflector (3), the beam combining mirror (31), the beam splitter (32), and the rear reflector (33) are all rotatably mounted on the surface of the bracket via a damping bearing; the reflector, the beam combining mirror (31), the beam splitter (32), and the rear reflector (33) are all coaxially fixed with a driven pulley (8); the driven pulley (8) is connected to the driving pulley (72) via a belt transmission; the driving pulley (72) is coaxially fixed with a driven gear (73); the driven gear (73) is meshingly connected to a driving gear (74); and the driving rod (9) can be selectively meshedly connected to the driving gear (74).

5. The method for detecting the optical crystal laser thermal lens effect according to claim 4, characterized in that: A tensioning wheel (76) is arranged in correspondence with the driving pulley (72), and a belt on the outer side of the driving pulley (72) passes around the tensioning wheel (76). The tensioning wheel (76) is swingably connected to the integrated box (71) via a swing frame (77). A stud (78) is rotatably connected to the surface of the swing frame (77). The surface of the integrated box (71) has a through opening (79). The stud (78) passes through the through opening (79) to the outside of the integrated box (71). A nut is threadedly connected to the surface of the stud (78). The nut contacts the outer wall of the integrated box (71) to pull the swing frame (77) outward, so that the tensioning wheel (76) tightens the belt.

6. The method for detecting the optical crystal laser thermal lens effect according to claim 4, characterized in that: The driving rod (9) comprises a rod body (91); a shaft cylinder (710) is provided on the surface of the integrated box (71); the rod body (91) is inserted into the integrated box (71) by linear sliding of the shaft cylinder (710); a plurality of pressure plates (93) are rotatably arranged around the outer end of the rod body (91); the inner edges of the pressure plates (93) are inclined toward the inner end of the rod body (91); a plurality of fins (92) are rotatably arranged around the inner end of the rod body (91) by means of a torsion spring; the inner edges of the fins (92) are inclined toward the outer end of the rod body (91); An axial rod (94) is arranged inside the rod body (91) for axial sliding. The axial rod (94) is connected to a spring for applying pressure to the outer end of the rod body (91). The two ends of the axial rod (94) are respectively fixed to a rear sphere (95) and a front sphere (96). The rear sphere (95) contacts the inner edge of the pressure plate (93), and the front sphere (96) contacts the inner edge of the fin (92). By pressing the pressure plate (93) to contact the rear sphere (95) and the front sphere (96) to move, the front sphere (96) squeezes the fin (92) to rotate and protrude from the surface of the rod body (91).

7. The method for detecting the optical crystal laser thermal lens effect according to claim 6, characterized in that: A plurality of tooth plates (75) are elastically rotated in the integrated box (71) by means of a torsion spring, and the tooth plates (75) are arranged across the driving rod (9) to engage with the driving gears (74) one by one. The fins (92) protrude from the surface of the rod body (91) to engage with the driving gears (74), and at the same time, the fins (92) push the tooth plates (75) to rotate and disengage from the engagement with the driving gears (74).

8. The method for detecting the optical crystal laser thermal lens effect according to claim 7, characterized in that: The portion where the tooth plate (75) is engaged with the driving gear (74) is an arc-shaped tooth surface, and the portion where the tooth plate (75) crosses the driving rod (9) is a smooth plate surface.

9. The method for detecting the optical crystal laser thermal lens effect according to claim 6, characterized in that: The inner wall of the shaft cylinder (710) is provided with a telescopic groove (99), in which a ball (98) slides elastically through a spring, and a plurality of annular grooves (97) are arranged on the surface of the rod body (91), in which the ball (98) can be inserted, and the spacing of the annular grooves (97) is the same as the spacing of the belt assembly.

Images