An alignment device and alignment method for cavity mirrors of a straight-cavity solid-state laser resonator

Abstract

The present invention discloses an alignment device and alignment method for the cavity mirrors of a straight-cavity solid-state laser resonator, belonging to the technical field of alignment of laser resonator cavities, and solving the problem of low alignment accuracy of the cavity mirrors of existing solid-state laser resonators; specifically, it includes a short-coherence light source, the short-coherence light source is connected with a coupler through an optical fiber; the output port of the coupler is respectively connected with a measurement arm and a reference arm through two optical fibers; the combined output port of the coupler is connected with a photodiode through an optical fiber, and the photodiode is connected with a control unit. In the present invention, the short-coherence interference measurement technology is used to accurately measure the actual cavity length of the straight-cavity solid-state laser resonator, and then according to the parameter indexes of the designed cavity length of the solid-state laser resonator designed in the early stage, an accurate assembly error value is obtained, and then the cavity mirrors of the resonator are accurately aligned, and the alignment accuracy is high.

Description

Technical Field

[0001] The present invention relates to the technical field of laser resonator alignment, and particularly to an alignment device and method for cavity mirrors of a linear cavity solid laser resonator. Background Art

[0002] A solid laser is a type of laser that uses solid laser materials as the working medium. Due to its advantages such as high output power, good beam quality, high conversion efficiency, and good pulse characteristics, it is widely used in fields such as medical treatment, communication, industry, and national defense. As a core component of a solid laser, the structure of the resonator not only determines the beam quality and output power of the laser, but also affects laser parameters such as the spectral characteristics and pulse characteristics of the laser. The definition of the resonator length is the equivalent optical path length between two mirrors, and its actual value is affected by various factors such as mechanical assembly errors, thermal deformation, and vibration interference. Existing research shows that when the cavity length offset exceeds a specific threshold, the output characteristics of the laser will deteriorate observably. Therefore, accurately aligning the cavity mirrors of the resonator and thus precisely controlling the cavity length of the resonator is of great significance for ensuring the stability of the laser output characteristics.

[0003] In a Chinese invention patent with the authorization announcement number CN109633921B, a laser cavity mirror auxiliary alignment device and its usage method are disclosed. In the laser cavity mirror auxiliary alignment method of this patent, an adjustable-focus visible laser is used as the reference light source, the center position of the reflected light spot on the observation screen is located by a light field camera, and the laser cavity mirror is clamped by a mirror frame robotic arm for alignment to achieve precise alignment of the laser cavity mirror. However, the high precision of this device depends on the performance and cooperation of each component, and during long-term use, it may affect the alignment accuracy and stability.

[0004] In a Chinese utility model patent with the authorization announcement number CN219458293U, an alignment device for a solid laser resonator assembly is disclosed. In the alignment device for the solid laser resonator assembly of this patent, a positioning reference is formed by a positioning support and a positioning bracket, the laser rod and the xenon lamp are quickly positioned and assembled by a pneumatic grasping tooling, and the parallelism of each end face of the resonator assembly is adjusted by means of equipment such as an internal focusing autocollimator parallel light tube, so as to achieve precise alignment of the solid laser resonator assembly. However, the equipment used has high requirements for the environment and operators, and the alignment efficiency and automation degree are low.

[0005] In a Chinese utility model patent with the authorization announcement number CN220692519U, an auxiliary alignment structure and an optical reflection cavity are disclosed. In the auxiliary alignment structure of this patent, the auxiliary mirror group has two working positions, namely collimation and light passing. It can receive the reflected light beam, and its angle and position can be flexibly adjusted, facilitating the collimation of the cavity mirror of the optical reflection cavity. The optical reflection cavity includes a cavity with adjustable vacuum degree, a cavity mirror, and this auxiliary alignment structure, and can efficiently and accurately align the cavity mirror in a vacuum environment. However, there are deficiencies such as complex structure leading to high manufacturing and maintenance costs, and the applicable range being limited to specific optical reflection cavities.

[0006] In summary, there are problems in the alignment of the cavity mirror of the existing solid laser resonator, such as low accuracy, being greatly affected by environmental factors, and relying on manual operation. Therefore, the present invention proposes a cavity mirror alignment device and alignment method for a straight-cavity solid laser resonator. Summary of the Invention

[0007] Aiming at the deficiencies existing in the prior art, the present invention provides a cavity mirror alignment device and alignment method for a straight-cavity solid laser resonator, which solves the problem of low alignment accuracy of the cavity mirror of the existing solid laser resonator.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A cavity mirror alignment device for a straight-cavity solid laser resonator includes a short-coherence light source, and the short-coherence light source is connected with a coupler through an optical fiber; the output port of the coupler is respectively connected with a measurement arm and a reference arm through two optical fibers; the combined output port of the coupler is connected with a photodiode through an optical fiber, and the photodiode is connected with a control unit;

[0010] The measurement arm includes a first adjustable collimator, and the input port of the first adjustable collimator is connected with the output port of the coupler through an optical fiber; an output mirror is arranged at the light output end of the first adjustable collimator, a total reflection mirror is arranged at the light transmission end of the output mirror, and the output mirror and the total reflection mirror are installed inside the cavity of the straight-cavity solid laser resonator; an electric control displacement stage is installed at the bottom of the total reflection mirror, and a three-dimensional adjustment frame is arranged at the bottom of the electric control displacement stage; the three-dimensional adjustment frame is arranged on the mounting frame assembly.

[0011] In this solution, a short-coherence light source emits a laser beam, and a coupler splits the beam emitted by the short-coherence light source. One beam travels through an optical fiber to the measurement arm, and the other beam travels through an optical fiber to the reference arm. The beams reflected back from the measurement arm and the reference arm enter the coupler and are combined. After combination, they are transmitted through an optical fiber to a photodiode, which converts the combined beam into an electrical signal and transmits it to a control unit. The control unit controls the reference arm to perform a scanning measurement, thereby achieving high-precision measurement of the actual cavity length of the resonator cavity of a straight-cavity solid-state laser. Then, according to the parameter indicators of the designed cavity length of the solid-state laser resonator cavity in the early stage, an accurate assembly error value is obtained, and then the cavity mirrors of the resonator cavity are precisely adjusted, and the adjustment accuracy can reach the micron level.

[0012] Further, the mounting frame assembly includes an optical air-bearing platform, on which a base is installed. A column is provided on the base, and a three-dimensional adjustment frame is supported on the column;

[0013] A support rod is installed on the optical air-bearing platform. A resonator holder is provided on the support rod, and the resonator cavity of the straight-cavity solid-state laser is fixed on the resonator holder. A cross bar is connected to the support rod, and a collimator adjustment frame is connected to the cross bar. A first adjustable collimator is installed on the collimator adjustment frame.

[0014] In this solution, the support rod is used to connect and support the cross bar and the resonator holder; the cross bar is used to connect the collimator adjustment frame and can be adjusted in height; the collimator adjustment frame can adjust the pitch angle of the first adjustable collimator; the resonator holder is used to clamp and fix the resonator cavity; the column is used to support devices such as the three-dimensional adjustment frame and the electric control displacement table; the base is used to fix the position of the column on the optical air-bearing platform and provide stability; the optical air-bearing platform provides stable support for the device and improves the stability of the overall system.

[0015] Further, the reference arm includes a second adjustable collimator. The input port of the second adjustable collimator is connected to the output port of the coupler through an optical fiber; a reference mirror is provided at the light output end of the second adjustable collimator.

[0016] In this solution, the reference mirror is the reflecting mirror of the optical path where the reference arm is located, and is installed on an automatic displacement table including a linear scale delay line, and is used to reflect the laser in the reference arm after passing through the delay line.

[0017] Second, based on the resonator cavity mirror alignment device of a straight-cavity solid-state laser provided in the first aspect, the present invention provides a method for aligning the resonator cavity mirrors of a straight-cavity solid-state laser, including the following steps:

[0018] S1: A short-coherence light source emits a beam, and the beam is transmitted to a coupler through an optical fiber;

[0019] S2: The coupler splits the light beam into two paths, one of which is transmitted through an optical fiber to the measurement arm, and the other is transmitted through an optical fiber to the reference arm;

[0020] S3: Adjust the measurement arm so that the two light beams are reflected by the measurement arm and the reference arm respectively and then return to the coupler along the optical fiber;

[0021] S4: The coupler combines the two light beams and transmits them through an optical fiber to a photodiode. The photodiode converts the optical signal into an electrical signal and transmits it to the control unit;

[0022] S5: The control unit controls the reference mirror in the reference arm to perform a scanning measurement, obtains the envelope information of the interference signal of the two light beams, and further determines the actual cavity length of the straight-cavity solid-state laser resonator; then, according to the error between the actual cavity length of the straight-cavity solid-state laser resonator and the designed cavity length of the straight-cavity solid-state laser resonator, the alignment is carried out.

[0023] In this solution, the short-coherence interference measurement technology is used to accurately measure the measured value of the actual cavity length of the straight-cavity solid-state laser resonator. After obtaining the measured value of the actual cavity length of the straight-cavity solid-state laser resonator, according to the parameter index of the designed cavity length of the straight-cavity solid-state laser resonator designed in the early stage, the accurate assembly error value is obtained, and the cavity mirror is accurately aligned according to the error value. The alignment accuracy is high and it is less affected by environmental factors.

[0024] Further, in S1, the light beam emitted by the short-coherence light source includes two parts, one part is the test light with a central wavelength of 1310 nm, and the other part is the red visible debugging light with a wavelength of 655 nm. The two light beams are output in a common path.

[0025] In this solution, part of the red visible debugging light is convenient for observing the light beam path when adjusting each optical component.

[0026] Further, S3 includes:

[0027] S301: Adjust the first adjustable collimator and the three-dimensional adjustment frame so that the output light beam of the first adjustable collimator is vertically incident on the three-dimensional adjustment frame;

[0028] S302: Install the cavity body of the straight-cavity solid-state laser resonator and make the cavity body of the straight-cavity solid-state laser resonator perpendicular to the optical air-bearing platform;

[0029] S303: Assemble the output mirror so that the output light beam of the first adjustable collimator is vertically incident on the center of the output mirror; adjust the angle of the output mirror so that the reflected light beam of the output mirror enters the light output port of the first adjustable collimator;

[0030] S304: Place the electro-controlled displacement stage on the three-dimensional adjustment frame, and place the total reflection mirror on the electro-controlled displacement stage; adjust the three-dimensional adjustment frame so that the reflected light beam of the total reflection mirror returns to the light outlet of the first adjustable collimator along the path of the original incident light beam.

[0031] S305: The reflected light beam of the output mirror and the reflected light beam of the total reflection mirror return to the coupler after passing through the first adjustable collimator.

[0032] Further, when adjusting the first adjustable collimator and the three-dimensional adjustment frame in S301, place a plane reflection mirror on the three-dimensional adjustment frame, and adjust the angles of the first adjustable collimator and the three-dimensional adjustment frame until the red visible debugging light is observed to be reflected back to the light outlet of the first adjustable collimator.

[0033] Further, S5 includes:

[0034] S501: Input measurement parameters in the control unit and start scanning measurement; the measurement parameters include the laser gain emitted by the first adjustable collimator, the optical material of the output mirror, and the initial position of the reference arm delay line scan.

[0035] S502: The control unit controls the reference mirror in the reference arm to perform scanning measurement. After the scanning measurement, two envelope peaks corresponding to the light reflected by the reflection surface of the output mirror close to the cavity and the light reflected by the total reflection mirror are displayed in the control unit. The positions of the peaks of the two envelope peaks are x1 and x2 respectively. x1 and x2 correspond to the positions of the reflection surface of the output mirror and the total reflection mirror respectively; the distance between the reflection surface of the output mirror close to the cavity and the total reflection mirror is obtained according to the position difference between x1 and x2, that is, the actual cavity length of the straight-cavity solid-state laser resonator.

[0036] S503: Compare the actual cavity length of the straight-cavity solid-state laser resonator obtained by measurement with the designed cavity length of the straight-cavity solid-state laser resonator to obtain the relative error of the distance between the output mirror and the total reflection mirror. Determine the moving direction and distance of the total reflection mirror according to this relative error, and use the electro-controlled displacement stage to move the total reflection mirror by a micron level.

[0037] S504: Repeat S501 - S503, measure the actual cavity length of the straight-cavity solid-state laser resonator multiple times and adjust the position of the total reflection mirror until the distance between the output mirror and the total reflection mirror meets the designed cavity length of the straight-cavity solid-state laser resonator; fix the total reflection mirror, and the alignment of the cavity mirrors of the straight-cavity solid-state laser resonator is completed.

[0038] The beneficial effects of the present invention are:

[0039] In the method for adjusting and aligning the cavity mirrors of the straight cavity solid laser provided by the present invention, the short coherence interference measurement technology is used to accurately measure the cavity length of the straight cavity solid laser resonator; the coherence length of the short coherence light source is relatively short, generally in the order of micrometers to hundreds of micrometers. Only when the optical path difference between the two beams of light is close to zero can obvious interference fringes be generated. By extracting the envelope information of the interference signal, the high-precision measurement of the cavity length of the straight cavity solid laser resonator is realized. Then, an electric control displacement stage and a three-dimensional adjustment frame are used to accurately adjust and align the cavity mirrors of the resonator. After adjustment, the actual cavity length of the straight cavity solid laser resonator can reach the micrometer level compared with the designed cavity length, and the adjustment accuracy is high.

[0040] The overall structure of the device for adjusting and aligning the cavity mirrors of the straight cavity solid laser resonator provided by the present invention is simple, and the degree of automation is high. It is suitable for the high-precision adjustment and alignment of the cavity mirrors of the straight cavity solid laser without an adjustment structure; the measuring arm adopts a vertical structure, and the overall structure is reliable and stable, which is convenient for the operators to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a schematic structural diagram of a device for adjusting and aligning the cavity mirrors of a straight cavity solid laser resonator according to the present invention;

[0042] Figure 2 is a schematic structural diagram of the measuring arm of the present invention;

[0043] Figure 3 is a schematic structural diagram when the reflected light beam of the total reflection mirror in the measuring arm of the present invention cannot enter the light output port of the first adjustable collimator;

[0044] Figure 4 is a schematic diagram of the simulated interference fringes of short coherence interference of the present invention;

[0045] Figure 5 is an interference envelope information diagram of measuring the cavity length of the straight cavity solid laser resonator by short coherence interference of the present invention.

[0046] REFERENCE SIGNS:

[0047] 1. Short coherence light source; 2. Coupler; 3. Measuring arm; 4. Reference arm; 5. Photodiode; 6. Control unit; 7. First adjustable collimator; 8. Cavity body of the straight cavity solid laser resonator; 9. Output mirror; 10. Total reflection mirror; 11. Electric control displacement stage; 12. Three-dimensional adjustment frame; 13. Reference mirror; 14. Collimator adjustment frame; 15. Cross bar; 16. Support rod; 17. Resonator holder; 18. Column; 19. Base; 20. Optical air-bearing platform; 21. Second adjustable collimator. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The following describes the specific embodiments of the present invention to facilitate those skilled in the art of this technical field to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art of this technical field, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.

[0049] Embodiment 1

[0050] As Figure 1 shown, this embodiment provides an alignment device for the cavity mirrors of a straight-cavity solid-state laser resonator. This alignment device for the cavity mirrors of a straight-cavity solid-state laser resonator uses short-coherence interferometry to accurately measure the actual cavity length of the straight-cavity solid-state laser resonator, and is equipped with an electric displacement stage 11 and a three-dimensional adjustment frame 12 for high-precision alignment of the cavity mirrors. Specifically, it includes:

[0051] A short-coherence light source 1, a coupler 2, a measurement arm 3, a reference arm 4, a photodiode 5, a control unit 6, and a mounting frame assembly;

[0052] Among them, the short-coherence light source 1 is connected to the coupler 2 through an optical fiber; the output ports of the coupler 2 are respectively connected to the measurement arm 3 and the reference arm 4 through two optical fibers; the measurement arm 3 is fixed on the mounting frame assembly; the short-coherence light source 1 emits a laser beam, and the coupler 2 splits the beam emitted by the short-coherence light source 1. One beam travels through the optical fiber to the measurement arm 3, and the other beam travels through the optical fiber to the reference arm 4. The combined output port of the coupler 2 is connected to the photodiode 5 through an optical fiber, and the photodiode 5 is connected to the control unit 6; the beams reflected back by the measurement arm 3 and the reference arm 4 enter the coupler 2 and are combined, and then are transmitted to the photodiode 5 through the optical fiber. The photodiode 5 converts the combined beam into an electrical signal and transmits it to the control unit 6.

[0053] As Figure 2 shown, the measurement arm 3 includes a first adjustable collimator 7, a cavity body 8 of a straight-cavity solid-state laser resonator, an output mirror 9, a total reflection mirror 10, an electric displacement stage 11, and a three-dimensional adjustment frame 12;

[0054] The input port of the first adjustable collimator 7 is connected to the output port of the fiber optic coupler 2 through an optical fiber, and the adjustable collimator converts the light beam transmitted from the coupler 2 into a collimated laser beam; an output mirror 9 is provided at the optical output end of the first adjustable collimator 7, and a total reflection mirror 10 is provided at the light transmission end of the output mirror 9. The output mirror 9 and the total reflection mirror 10 are installed inside the cavity 8 of the straight-cavity solid-state laser resonator; an electronically controlled displacement stage 11 is installed at the bottom of the total reflection mirror 10, and the electronically controlled displacement stage 11 can drive the total reflection mirror 10 to achieve micron-level displacement; a three-dimensional adjustment bracket 12 is provided at the bottom of the electronically controlled displacement stage 11, and the three-dimensional adjustment bracket 12 can perform all-round adjustment of the total reflection mirror 10 in the horizontal direction and the pitch direction; the three-dimensional adjustment bracket 12 is provided on the mounting bracket assembly.

[0055] The mounting bracket assembly includes an optical air-bearing platform 20, a base 19, a column 18, a support rod 16, a resonator holder 17, a cross bar 15, and a collimator adjustment bracket 14;

[0056] The optical air-bearing platform 20 is provided with a base 19, and a column 18 is provided on the base 19. The three-dimensional adjustment bracket 12 is supported on the column 18; the optical air-bearing platform 20 is provided with a support rod 16, and a resonator holder 17 is provided on the support rod 16. The cavity 8 of the straight-cavity solid-state laser resonator is fixed on the resonator holder 17; a cross bar 15 is connected to the support rod 16, and a collimator adjustment bracket 14 is connected to the cross bar 15. The first adjustable collimator 7 is installed on the collimator adjustment bracket 14, and the collimator adjustment bracket 14 can adjust the pitch angle of the first adjustable collimator 7.

[0057] The reference arm 4 includes a second adjustable collimator 21 and a reference mirror 13; the input port of the second adjustable collimator 21 is connected to the output port of the coupler 2 through an optical fiber; a reference mirror 13 is provided at the optical output end of the second adjustable collimator 21; the reference mirror 13 is the reflecting mirror of the optical path where the reference arm 4 is located, and is installed on an automatic displacement stage including a linear scale delay line to reflect the laser light after passing through the delay line in the reference arm 4.

[0058] Embodiment 2

[0059] Based on the straight-cavity solid-state laser resonator mirror alignment device provided in Embodiment 1, this embodiment provides a method for aligning the mirrors of a straight-cavity solid-state laser resonator, including the following steps:

[0060] S1: The short coherence light source 1 emits a light beam, and the light beam is transmitted to the coupler 2 through an optical fiber;

[0061] The light beam emitted by the short coherence light source 1 includes two parts. One part is the test light with a central wavelength of 1310 nm, and the other part is the red visible debugging light with a wavelength of 655 nm. The two light beams are output in a common path; the red visible debugging light is convenient for observing the light beam path when adjusting each optical component.

[0062] S2: The coupler 2 splits the light beam into two paths. One path is transmitted through an optical fiber to the measurement arm 3, and the other path is transmitted through an optical fiber to the reference arm 4.

[0063] S3: Adjust the measurement arm 3 so that the two light beams are reflected by the measurement arm 3 and the reference arm 4 respectively and then return to the coupler 2 along the optical fiber. Specifically, it includes:

[0064] S301: Adjust the first adjustable collimator 7 and the three-dimensional adjustment frame 12 so that the outgoing light beam of the first adjustable collimator 7 is perpendicularly incident on the three-dimensional adjustment frame 12. When adjusting, place a plane mirror on the three-dimensional adjustment frame 12 and adjust the angles of the first adjustable collimator 7 and the three-dimensional adjustment frame 12 until the red visible debugging light is observed to be reflected back to the light outlet of the first adjustable collimator 7.

[0065] S302: Install the straight-cavity solid laser resonator cavity 8 and make the straight-cavity solid laser resonator cavity 8 perpendicular to the optical air-bearing platform 20.

[0066] S303: Assemble the output mirror 9 so that the outgoing light beam of the first adjustable collimator 7 is perpendicularly incident on the exact center of the output mirror 9. Adjust the angle of the output mirror 9 so that the reflected light beam of the output mirror 9 enters the light outlet of the first adjustable collimator 7.

[0067] S304: Place the electric displacement stage 11 on the three-dimensional adjustment frame 12 and place the total reflection mirror 10 on the electric displacement stage 11. Adjust the three-dimensional adjustment frame 12 so that the reflected light beam of the total reflection mirror 10 returns to the light outlet of the first adjustable collimator 7 along the path of the original incident light beam. If the direction and angle of the three-dimensional adjustment frame 12 cannot be adjusted properly, the reflected light beam of the total reflection mirror 10 cannot enter the light outlet of the first adjustable collimator 7, as Figure 3 shown;

[0068] In this step, when assembling the total reflection mirror 10, make the actual cavity length of the straight-cavity solid laser resonator approximately equal to the designed cavity length of the straight-cavity solid laser resonator, reducing the subsequent installation and adjustment workload.

[0069] S305: The reflected light beams of the output mirror 9 and the total reflection mirror 10 return to the coupler 2 after passing through the first adjustable collimator 7.

[0070] S4: The coupler 2 combines the two light beams into one path and transmits it through an optical fiber to the photodiode 5. The photodiode 5 converts the optical signal into an electrical signal and transmits it to the control unit 6.

[0071] S5: The control unit 6 controls the reference mirror 13 in the reference arm 4 to perform a scanning measurement, obtains the envelope information of the interference signal of the two light beams, and further determines the actual cavity length of the straight-cavity solid laser resonator. Then, perform installation and adjustment according to the error between the actual cavity length of the straight-cavity solid laser resonator and the designed cavity length of the straight-cavity solid laser resonator. Specifically, it includes:

[0072] S501: Input measurement parameters into the control unit 6; the measurement parameters include the output laser gain of the first adjustable collimator, the optical material of the output mirror, the initial position of the reference arm delay line scan, etc.;

[0073] S502: The control unit 6 controls the reference mirror 13 in the reference arm 4 to perform a scanning measurement. After the scanning measurement, two envelope peaks corresponding to the light reflected by the reflecting surface near the cavity inside the output mirror 9 and the light reflected by the total reflection mirror 10 are displayed in the control unit 6;

[0074] As known from physical optics knowledge, the coherence length of a Gaussian light source can be expressed as:

[0075]

[0076] where, is the central wavelength of the test light, is the spectral width, ln is the natural logarithm with the natural number e as the base; π is the pi;

[0077] In this embodiment, the central wavelength of the test light is 1310 nm, and the spectral width is 30 nm, and the coherence length is obtained as 25.24 μm;

[0078] Taking the zero point of the reference mirror 13 position as the center, corresponding to the position of the zero point of the group delay difference, that is, the position where the optical path differences of the two optical paths are equal at the peak position of the envelope peak, as Figure 4 shown;

[0079] Define the light reflected by the reflecting surface near the cavity inside the output mirror 9 as R1, and the light returned by the total reflection mirror 10 as R2. The peak positions of the envelope peaks of the light R1 reflected by the reflecting surface near the cavity inside the output mirror 9 and the light R2 reflected by the total reflection mirror 10 are x1 and x2 respectively. x1 and x2 correspond to the positions of the reflecting surface of the output mirror 9 and the total reflection mirror 10 respectively; the distance between the reflecting surface near the cavity inside the output mirror 9 and the total reflection mirror 10 is obtained according to the position difference between x1 and x2, that is, the actual cavity length of the straight-cavity solid-state laser resonator;

[0080] S503: Compare the actual cavity length of the straight-cavity solid-state laser resonator obtained by measurement with the designed cavity length of the straight-cavity solid-state laser resonator to obtain the relative error of the distance between the output mirror 9 and the total reflection mirror 10. Determine the moving direction and distance of the total reflection mirror 10 according to this relative error, and use the electric control displacement stage 11 to accurately move the total reflection mirror 10 at the micron level;

[0081] S504: Repeat the execution of S501~S503, measure the actual cavity length of the straight cavity solid laser resonator multiple times and adjust the position of the total reflection mirror 10 until the distance between the output mirror 9 and the total reflection mirror 10 meets the designed cavity length of the straight cavity solid laser resonator; fix the total reflection mirror 10, and the alignment of the cavity mirrors of the straight cavity solid laser resonator is completed.

[0082] Those of ordinary skill in the art will realize that the embodiments herein are for helping the reader understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations that do not depart from the essence of the present invention according to these technical revelations disclosed in the present invention, and these deformations and combinations are still within the protection scope of the invention.

Claims

1. An adjusting device for the cavity mirrors of a straight-cavity solid-state laser resonator, characterized in that: It includes a short coherence light source (1), and the short coherence light source (1) is connected with a coupler (2) through an optical fiber; the output port of the coupler (2) is respectively connected with a measurement arm (3) and a reference arm (4) through two optical fibers; the combined output port of the coupler (2) is connected with a photodiode (5) through an optical fiber, and the photodiode (5) is connected with a control unit (6); The measurement arm (3) includes a first adjustable collimator (7), and the input port of the first adjustable collimator (7) is connected with the output port of the coupler (2) through an optical fiber; an output mirror (9) is arranged at the light output end of the first adjustable collimator (7), a total reflection mirror (10) is arranged at the light transmission end of the output mirror (9), and both the output mirror (9) and the total reflection mirror (10) are installed inside the cavity of a straight cavity type solid laser resonator (8); an electric control displacement stage (11) is installed at the bottom of the total reflection mirror (10), and a three-dimensional adjustment frame (12) is arranged at the bottom of the electric control displacement stage (11); the three-dimensional adjustment frame (12) is arranged on a mounting frame assembly; The reference arm (4) includes a second adjustable collimator (21), and the input port of the second adjustable collimator (21) is connected with the output port of the coupler (2) through an optical fiber; a reference mirror (13) is arranged at the light output end of the second adjustable collimator (21).

2. The collimating device for the cavity mirrors of the straight-cavity solid-state laser resonator according to claim 1, wherein: The mounting frame assembly includes an optical air-bearing platform (20), a base (19) is installed on the optical air-bearing platform (20), a column (18) is arranged on the base (19), and the three-dimensional adjustment frame (12) is supported on the column (18); A support rod (16) is installed on the optical air-bearing platform (20), a resonator gripper (17) is arranged on the support rod (16), and the straight cavity type solid laser resonator cavity (8) is fixed on the resonator gripper (17); a cross bar (15) is connected to the support rod (16), a collimator adjustment frame (14) is connected to the cross bar (15), and the first adjustable collimator (7) is installed on the collimator adjustment frame (14).

3. An alignment method for an alignment device of a cavity mirror of a straight cavity solid laser resonator according to any one of claims 1 to 2, characterized in that It includes the following steps: S1: The short coherence light source (1) emits a light beam, and the light beam is transmitted to the coupler (2) through an optical fiber; S2: The coupler (2) splits the light beam into two paths, one path is transmitted to the measurement arm (3) through an optical fiber, and the other path is transmitted to the reference arm (4) through an optical fiber; S3: Adjust the measurement arm (3) so that the two light beams are reflected by the measurement arm (3) and the reference arm (4) respectively and then return to the coupler (2) along the optical fiber; S4: The coupler (2) combines the two light beams and transmits them to the photodiode (5) through an optical fiber, and the photodiode (5) converts the optical signal into an electrical signal and transmits it to the control unit (6); S5: The control unit (6) controls the reference mirror (13) in the reference arm (4) to perform a scanning measurement, obtains the envelope information of the interference signal of the two light beams, and further determines the actual cavity length of the straight cavity type solid laser resonator; Then, alignment is performed according to the error between the actual cavity length of the straight cavity type solid laser resonator and the designed cavity length of the straight cavity type solid laser resonator.

4. The alignment method of the cavity mirror of the straight-cavity solid laser resonator alignment device according to claim 3, characterized in that: In S1, the light beam emitted by the short-coherence light source (1) includes two parts. One part is the test light with a central wavelength of 1310 nm, and the other part is the red visible debugging light with a wavelength of 655 nm. The two light beams are output through the same path.

5. The alignment method of the cavity mirror of the straight cavity solid laser resonator alignment device according to claim 4, characterized in that, S3 includes: S301: Adjust the first adjustable collimator (7) and the three-dimensional adjustment frame (12) so that the outgoing light beam of the first adjustable collimator (7) is vertically incident on the three-dimensional adjustment frame (12); S302: Install the straight-cavity solid laser resonator cavity (8) and make the straight-cavity solid laser resonator cavity (8) perpendicular to the optical air-bearing platform (20); S303: Assemble the output mirror (9) so that the outgoing light beam of the first adjustable collimator (7) is vertically incident on the exact center of the output mirror (9); Adjust the angle of the output mirror (9) so that the reflected light beam of the output mirror (9) enters the light outlet of the first adjustable collimator (7); S304: Place the electric control displacement stage (11) on the three-dimensional adjustment frame (12) and place the total reflection mirror (10) on the electric control displacement stage (11); Adjust the three-dimensional adjustment frame (12) so that the reflected light beam of the total reflection mirror (10) returns to the light outlet of the first adjustable collimator (7) along the path of the original incident light beam; S305: The reflected light beam of the output mirror (9) and the reflected light beam of the total reflection mirror (10) return to the coupler (2) through the first adjustable collimator (7).

6. The alignment method of the cavity mirror alignment device of the straight cavity solid laser resonator according to claim 5, characterized in that; When adjusting the first adjustable collimator (7) and the three-dimensional adjustment frame (12) in S301, place a plane mirror on the three-dimensional adjustment frame (12), and adjust the angles of the first adjustable collimator (7) and the three-dimensional adjustment frame (12) until the red visible debugging light is observed to be reflected back to the light outlet of the first adjustable collimator (7).

7. The alignment method of the cavity mirror alignment device for the straight cavity solid laser resonator according to claim 5, characterized in that, S5 includes: S501: Input measurement parameters into the control unit (6); the measurement parameters include the laser gain of the outgoing light of the first adjustable collimator, the optical material of the output mirror, and the initial position of the reference arm delay line scan; S502: The control unit (6) controls the reference mirror (13) in the reference arm (4) to perform a scanning measurement. After the scanning measurement, two envelope peaks corresponding to the light reflected by the reflection surface near the cavity of the output mirror (9) and the light reflected by the total reflection mirror (10) are displayed in the control unit (6). The positions of the peaks of the two envelope peaks are x1 and x2 respectively. x1 and x2 correspond to the positions of the reflection surface of the output mirror (9) and the total reflection mirror (10) respectively; Calculate the distance between the reflection surface near the cavity of the output mirror (9) and the total reflection mirror (10) based on the position difference between x1 and x2, that is, the actual cavity length of the straight-cavity solid laser resonator; S503: Compare the actual cavity length of the straight-cavity solid laser resonator obtained by measurement with the designed cavity length of the straight-cavity solid laser resonator to obtain the relative error of the distance between the output mirror (9) and the total reflection mirror (10). Determine the moving direction and distance of the total reflection mirror (10) based on this relative error, and use the electric control displacement stage (11) to perform a micron-level movement on the total reflection mirror (10); S504: Repeat the execution of S501 - S503 to measure the actual cavity length of the straight - cavity solid - state laser resonator multiple times and adjust the position of the total - reflection mirror (10) until the distance between the output mirror (9) and the total - reflection mirror (10) meets the designed cavity length of the straight - cavity solid - state laser resonator; fix the total - reflection mirror (10), and the alignment of the cavity mirrors of the straight - cavity solid - state laser resonator is completed.

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