Gas cavity optical axis automatic adjustment system and method

Abstract

The present invention provides a gas cavity optical axis automatic adjustment system, comprising a laser generator, a cavity mirror, an optical cavity, a Segnac interferometer, an adjustable iris, and an image feedback processing structure. The image feedback processing structure includes an image acquisition module, a data processing module, and a feedback control module. The image acquisition module is configured to acquire a spot image formed by a light beam at a certain position in the optical path; the data processing module is configured to analyze the spot image acquired by the image acquisition module and send a signal to the feedback control module based on the analysis result; and the feedback control module receives the signal sent by the data processing module and adjusts the adjustable iris or cavity mirror based on the signal. The gas cavity optical axis adjustment system and method provided by the present invention utilize a combination of image feedback processing technology and Segnac interferometer technology to achieve coaxial adjustment of the mirror cavity system, greatly improving the degree of automation of detection.

Description

Technical Field

[0001] The present invention relates to the technical field of optical equipment, and in particular to a gas cavity optical axis automatic adjustment system and method. Background Art

[0002] The emergence of laser absorption spectroscopy based on high-quality optical cavities has revolutionized spectroscopy. In particular, new, highly sensitive spectroscopy techniques, such as cavity ring-down spectroscopy, have become mainstream in spectral detection due to their simpler structure and higher sensitivity. They are powerful tools for analyzing a variety of trace substances and are widely used in the qualitative and quantitative analysis of trace gaseous substances.

[0003] As is well known, cavity ring-down spectroscopy relies on a resonant cavity. A typical resonant cavity consists of two mirrors coated with a highly reflective coating. When incident light enters the cavity, it undergoes multiple reflections between the mirrors before being output. If the cavity is filled with the gas being measured (also called a gas cavity or gas absorption cavity), the multiple reflections significantly increase the effective absorption pathlength, thereby improving the sensitivity of gas spectrum detection. The basic principle of cavity ring-down spectroscopy is that continuous laser light is injected into a resonant cavity containing the membrane to be measured. Once stable laser oscillation is established within the cavity, the light source is rapidly disconnected by a high-speed optical switch. Thereafter, the output light intensity of the cavity decays exponentially, and the decay time constant (the time it takes for the light intensity to drop to 1 / e of its initial value) is simply inversely proportional to the total cavity loss. Therefore, the total cavity loss can be determined by measuring the decay time, and the absorption coefficient of the gas can be determined by comparing the loss difference between the cavity filled with and without gas. From this, we can see that how to establish stable excitation in the resonant cavity is the first problem that needs to be solved. The important factor affecting whether the resonant cavity can achieve stable excitation is the closure quality of the laser circuit, that is, the closure quality of the laser circuit of the resonant cavity directly affects the results of gas detection. If the laser beam cannot propagate along the most ideal circuit (that is, the circuit with the smallest total loss, in which case the laser beam is coaxial with the two cavity mirrors), then it will cause the loss in the cavity to increase and the gas absorption optical path to decrease. The quality of the laser circuit closure is directly related to the degree of coaxiality between the laser beam and the two cavity mirrors. The higher the coaxiality, the better the laser circuit closure quality.

[0004] To ensure the closure quality of the laser circuit, conventional techniques can be used to control mode matching between the laser beam and the gas cavity (i.e., resonant cavity) by scanning the laser frequency or the cavity length, thereby achieving a longer gas absorption path. Specifically, after the gas cavity is essentially closed, a periodic signal is used to scan the cavity length or the incident laser frequency. A photodetector with an appropriate wavelength and gain is used to receive the transmission (or reflection) signal from the gas cavity. The transmission (or reflection) peak signal of the cavity is then observed by connecting it to an oscilloscope. When mode matching is suboptimal, many higher-order spatial modes are excited. Due to competition within the cavity mode, the presence of these higher-order modes means that the desired fundamental mode fraction will be less than expected, indicating excessive intracavity loss. In this case, the gas cavity loss is highly sensitive to subtle changes within the cavity, allowing for fine-tuning of the cavity mirror angle to close the cavity laser circuit and minimize intracavity loss. However, this method has several drawbacks: 1. It relies on manual assembly, which is time-consuming and complex; 2. It suffers from poor batch assembly consistency, low first-time completion rate, and low batch assembly efficiency; and 3. It is prone to device contamination.

[0005] Therefore, the present application aims to provide a laser gas cavity optical axis adjustment system and method, which can be used to automatically detect and adjust the optical axis of the gas cavity to achieve the purpose of coaxiality between the gas cavity and the laser beam. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and to provide a laser gas cavity optical axis adjustment system and method, which can automatically control the laser gas cavity optical axis and achieve coaxial adjustment of the gas cavity system.

[0007] The technical solution of the present invention is: firstly, a gas cavity optical axis automatic adjustment system is provided, which includes a laser generator, a cavity mirror, an optical cavity, a Segnac interferometer, an adjustable diaphragm, and an image feedback processing structure;

[0008] The laser generator is used to emit a light beam, for example, a helium-neon laser can be used;

[0009] The cavity mirror is used to be installed at the front and rear ends of the optical cavity to form a gas cavity;

[0010] The Segnac interferometer is used to split the light beam emitted by the laser generator into two beams, which overlap in space and are respectively emitted into the front and rear ends of the optical cavity;

[0011] The adjustable iris is used to collimate and limit the light beam in the optical path;

[0012] The image feedback processing structure includes an image acquisition module, a data processing module and a feedback control module, wherein:

[0013] The image acquisition module is used to collect the spot image formed by the light beam at a certain position in the light path;

[0014] The data processing module is used to analyze the spot image obtained by the image acquisition module and send a signal to the feedback control module based on the analysis result;

[0015] The feedback control module receives the signal sent by the data processing module and adjusts the adjustable aperture or cavity mirror according to the signal.

[0016] Furthermore, the Segnac interferometer is composed of a non-polarizing beam splitter cube and a reflector; specifically, it is composed of a first non-polarizing beam splitter cube and three reflectors.

[0017] Furthermore, there are multiple image acquisition modules and feedback control modules, and one image acquisition module is connected to one feedback control module.

[0018] Furthermore, there are two image acquisition modules, which are respectively arranged at the front and rear ends of the optical cavity, and there are two feedback control modules, which are also arranged at the two ends of the optical cavity.

[0019] Furthermore, the image acquisition module adopts an industrial camera, such as a CCD camera or a CMOS camera.

[0020] Furthermore, the data processing module has a built-in image analysis algorithm for calculating the center coordinate information of the spot image; the data processing module can be an electronic device such as a single-chip microcomputer or a computer; the image analysis algorithm includes a center of gravity algorithm, a Hough circle detection algorithm, etc.

[0021] Furthermore, the feedback control module is a multi-dimensional mobile platform, such as an electrically controlled six-axis translation platform, an electrically controlled five-axis translation platform, etc.

[0022] Furthermore, there are multiple adjustable irises, and each two form a group; preferably, there are four adjustable irises, divided into two groups.

[0023] Furthermore, the gas cavity optical axis automatic adjustment system also includes a climbing frame, which is used to raise the optical path. The climbing frame includes two high-reflection mirrors. After the laser beam is reflected by the two high-reflection mirrors, the vertical height position of the beam can be changed.

[0024] The present invention also provides a method for automatically adjusting the optical axis of a gas cavity, which uses the above-mentioned automatic adjustment system for the optical axis of a gas cavity, and includes the following steps:

[0025] S1. Start the laser generator, so that the light beam emitted by the laser generator enters the Segnac interferometer and is collimated by the first set of adjustable irises. The light beam after passing through the Segnac interferometer is divided into a reflected beam and a transmitted beam. These two beams rotate clockwise and counterclockwise, respectively, and finally return to the first non-polarizing beam splitter cube in the Segnac interferometer for coupling.

[0026] The reflected light beam from the first non-polarizing beam splitter cube is reflected by the second non-polarizing beam splitter cube and then enters the first image acquisition module. Simultaneously, the transmitted light beam from the first non-polarizing beam splitter cube is reflected by the third non-polarizing beam splitter cube and then enters the second image acquisition module. The first image acquisition module and the second image acquisition module respectively record image information generated by the corresponding light beams and transmit the image information to the data processing module for processing. After processing, the center coordinates of the corresponding light spots are obtained and recorded as the initial coordinates.

[0027] S2. Install a second set of adjustable irises on both sides of the optical cavity to basically align the optical cavity and the light beam to ensure that the light beam passes through the center of the cavity. Then, fix the optical cavity and remove the second set of adjustable irises.

[0028] S3. Insert an opaque metal piece into the optical cavity to prevent the light beam from penetrating the optical cavity, thereby destroying the interference condition and preventing mixed and messy images caused by the superposition of multiple Newton rings. Install a feedback control module on the left side of the optical cavity and fix the left cavity mirror on the feedback control module. At this time, the transmitted light of the first non-polarized beam splitter cube will be reflected on the surface of the left cavity mirror, and after being reflected by the second non-polarized beam splitter cube, it enters the first image acquisition module to generate a spot image. The obtained spot image information is transmitted to the data processing module for analysis and processing to obtain the center coordinates of the spot image, and the center coordinates are compared with the initial The initial coordinates are compared to obtain the error value between the two coordinates; then the data processing module sends a corresponding signal to the feedback control module according to the error value, and the feedback control module automatically drives the cavity mirror to perform angular deflection or axial movement to reduce the error value between the coordinates until the error value between the coordinates is within the preset range; finally, the center coordinates of the light spot are calculated again using the center of gravity algorithm and the Hough circle detection algorithm. When the error of the obtained center coordinate is within the set range, it is considered that the left cavity mirror is coaxial with the laser beam and the optical cavity. At this time, the left cavity mirror is fixed on the optical cavity; the adjustment and installation process of the right cavity mirror is the same.

[0029] Furthermore, in step S3, the center coordinates calculated using the center of gravity algorithm are compared with the initial coordinates, and the angular deflection of the cavity mirror is adjusted based on the comparison results. The center coordinates calculated using the Hough circle detection are compared with the initial coordinates, and the axial displacement of the cavity mirror is adjusted based on the difference. After the previous adjustment movement is completed, the two methods are used again for detection. When the difference between the detection result of the center of gravity algorithm and the initial coordinates and the difference between the detection result of the Hough circle and the initial coordinates are both less than the specified error range, the feedback is stopped.

[0030] Furthermore, in step S1, the light beam emitted by the laser is first passed through a climbing frame to raise the optical path, and then is emitted into the Segnac interferometer.

[0031] Furthermore, the image acquisition module is a CCD camera; the data processing module is an industrial computer and has built-in image analysis algorithm software, which is used to calculate the center coordinate information of the spot image; there can be multiple algorithms, including center of gravity algorithm, Hough circle detection algorithm, etc.; the feedback control module is an electrically controlled six-axis translation stage.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The gas cavity optical axis adjustment system and method provided by the present invention utilizes a combination of image feedback processing technology and Sagnac interferometer technology to achieve coaxial adjustment of the mirror cavity system, and is particularly suitable for a two-mirror cavity system. Furthermore, the image feedback processing structure greatly improves the degree of automation of detection. At the same time, the use of the Sagnac interferometer avoids the disadvantage of the traditional adjustment method, in which multiple Newton interference rings overlap each other to form a cluttered pattern between the two cavity mirrors, making it impossible for the camera image program to distinguish.

[0034] 2. The system has a simple structure; it does not require complex electronic equipment and observation equipment; nor does it require complex circuit design. The simple electronic circuit shortens the system assembly time, ensures good consistency during batch assembly, and increases installation efficiency, which is conducive to its promotion and use and can replace manual operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic diagram of the three-dimensional structure of Example 1 of the present invention;

[0036] Figure 2 This is a schematic diagram of Example 1 of the present invention after omitting the supporting structure;

[0037] Figure 3 1 is a schematic diagram of the optical path structure of Example 1 of the present invention;

[0038] Figure 4 This is a schematic diagram of the optical path structure of Example 1 of the present invention without installing the cavity mirror and the optical cavity;

[0039] Figure 5 This is a schematic diagram of the optical path during the adjustment process of Example 1 of the present invention;

[0040] Figure 6 It is the overall flow chart of the regulation method of the present invention;

[0041] Figure 7 It is a flow chart of the image detection and processing stage of the present invention;

[0042] In the figure: 1-laser generator, 2-climbing frame, 30-first non-polarizing beam splitter cube, 31-second non-polarizing beam splitter cube, 32-third non-polarizing beam splitter cube, 41, 42, 43-reflecting mirrors, 51, 52, 53, 54-adjustable apertures, 61-first image acquisition module, 62-second image acquisition module, 7-optical cavity, 81, 82-cavity mirrors, 91, 92-electrically controlled six-axis translation stages. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below with reference to specific embodiments. Methods or functional components not specifically described in the embodiments are all prior art.

[0044] Example 1

[0045] like Figure 1-5 As shown, this embodiment is a gas cavity optical axis automatic adjustment system, including a laser generator 1, a cavity mirror, an optical cavity 7, a Segnac interferometer, an adjustable aperture, and an image feedback processing structure;

[0046] The laser generator 1 is used to emit a light beam, and in this embodiment, a helium-neon laser is used;

[0047] The optical cavity 7 is fixed in the optical path by a cavity fixture 71; the cavity mirror is used to be installed at the front and rear ends of the optical cavity 7 to form a gas cavity, and the cavity fixture 71 adopts an adjustable fixture, which facilitates the rapid adjustment of the angle and position of the optical cavity 7, so that the optical cavity and the light beam are coaxial; in this embodiment, the length and inner diameter of the cavity cannot be changed, and external threads are set on the inner side of the two end heads to facilitate the connection of the internal threaded aperture.

[0048] The Segnac interferometer is used to split the light beam emitted by the laser generator 1 into two beams, which overlap in space and are respectively emitted into the front and rear ends of the optical cavity 7;

[0049] The adjustable iris is used to collimate and limit the light beam in the optical path, and the adjustable iris is provided with a pull rod;

[0050] The image feedback processing structure includes an image acquisition module, a data processing module and a feedback control module, wherein:

[0051] The image acquisition module is used to capture the spot image formed by the light beam at a certain position in the optical path; the data processing module is used to analyze the spot image obtained by the image acquisition module and send a signal to the feedback control module based on the analysis result. The feedback control module receives the signal sent by the data processing module and adjusts the adjustable aperture or cavity mirror based on the signal.

[0052] In this embodiment, the Segnac interferometer is composed of a non-polarization beam splitter cube and a reflector; specifically, the Segnac interferometer is composed of a first non-polarization beam splitter cube 3030 and three reflectors (41, 42, 43).

[0053] In this embodiment, there are two image acquisition modules and two feedback control modules, and one image acquisition module is connected to one feedback control module; and the two image acquisition modules are respectively arranged at the front and rear ends of the optical cavity 7, and there are two feedback control modules, which are also arranged at both ends of the optical cavity 7.

[0054] In this embodiment, the image acquisition module is a CCD working camera, model MV-SUA501GM; the data processing module is a computer, which is installed with software of an image analysis algorithm for calculating the center coordinate information of the spot image; the image analysis algorithm includes a center of gravity algorithm and a Hough circle detection algorithm.

[0055] In this embodiment, the feedback control modules are an electrically controlled six-axis translation platform 91 and an electrically controlled six-axis translation platform 92 , both of which can perform angular and axial movement adjustments.

[0056] In this embodiment, there are four adjustable irises, namely irises 51 - 54 , wherein irises 51 and 54 form a first group, and irises 52 and 53 form a second group.

[0057] In this embodiment, the adjustment system further includes a climbing frame 22, which is used to elevate the optical path. The climbing frame 22 includes two high-reflection mirrors. After the laser beam is reflected by the two high-reflection mirrors, the vertical height position of the beam can be changed.

[0058] The basic principle of this embodiment is to first determine a reference optical axis, measured without the gas cavity installed; then use this reference optical axis to verify and calibrate the optical axis within the gas cavity system. The optical axis information within the gas cavity system is carried by the laser beam reflected or transmitted by the optical cavity 7. By detecting the Newton ring interference fringes generated at the reflected or transmitted end, the axial and angular parameters of the cavity mirror can be adjusted in real time to ensure the overall coaxiality of the gas cavity system.

[0059] The present invention also provides a method for automatically adjusting the optical axis of a gas cavity, which is used in the above-mentioned automatic adjustment system for the optical axis of a gas cavity. The core process of the automatic adjustment method is shown in the attached figure. Figure 6 As shown, the specific steps include:

[0060] S1. Start the laser generator 1. The light beam emitted by the laser first passes through the climbing frame 2 to raise the optical path, and then enters the Segnac interferometer, and the light beam in the optical path is collimated by the first set of adjustable apertures; so that the light beam after passing through the Segnac interferometer is divided into a reflected light beam and a transmitted light beam; and these two beams of light will rotate clockwise and counterclockwise respectively, and finally return to the first non-polarizing beam splitter cube 30 in the Segnac interferometer for coupling; at this time, it is necessary to detect the coupling interference pattern at the first non-polarizing beam splitter cube 30. In theory, the higher the interference degree, the higher the spatial overlap of the two light beams, and the higher the positioning accuracy of the reference optical axis.

[0061] The reflected light beam from the first non-polarizing beam splitter cube 30 is reflected by the second non-polarizing beam splitter cube 31 and then enters the first image acquisition module 61 (i.e., CCD1). Simultaneously, the transmitted light beam from the first non-polarizing beam splitter cube 30 is reflected by the third non-polarizing beam splitter cube 32 and then enters the second image acquisition module 62 (i.e., CCD2). The first image acquisition module 61 and the second image acquisition module 62 respectively record the image information generated by the corresponding light beams and transmit the image information to the data processing module for processing. After processing, the center coordinates of the corresponding light spots are obtained and recorded as the initial coordinates. Thus, the reference optical axis is established.

[0062] S2. Install a second set of adjustable irises on both sides of the optical cavity 7. Install the optical cavity into the optical path using the cavity fixture 71. Basically align the optical cavity 7 and the light beam to ensure that the light beam passes through the center of the cavity. Then, fix the optical cavity 7 and remove the second set of adjustable irises.

[0063] S3. Install the left laparoscope

[0064] An opaque metal piece is inserted into the optical cavity 7 to prevent the light beam from penetrating the optical cavity 7, thereby destroying the interference condition and preventing a mixed and chaotic image caused by the superposition of multiple Newton rings. A feedback control module is installed on the left side of the optical cavity 7, and the left cavity mirror 81 is fixed to the feedback control module. At this time, the transmitted light of the first non-polarizing beam splitter cube 30 is reflected on the surface of the left cavity mirror. After being reflected by the second non-polarizing beam splitter cube 31, a spot image is generated in the CCD1. The obtained spot image information is transmitted to the data processing module for analysis and processing to obtain the center coordinates of the spot image, and the center coordinates are compared with the initial coordinates. A comparison is performed to obtain the error value between the two coordinates; then the data processing module sends a corresponding signal to the feedback control module according to the error value, and the feedback control module automatically drives the left cavity mirror 81 to perform angular deflection or axial movement to reduce the error value between the coordinates until the error value between the two coordinates is within the preset range; finally, the center coordinates of the light spot are calculated again using the center of gravity algorithm and the Hough circle detection algorithm. When the error of the obtained center coordinates is within the set range, it is considered that the left cavity mirror 81 is coaxial with the laser beam and the optical cavity 7. At this time, the left cavity mirror is fixed on the optical cavity 7; the connection can be fixed by UV glue.

[0065] S4. Install the right laparoscope

[0066] An opaque metal piece is inserted into the optical cavity 7 to prevent the light beam from penetrating the optical cavity 7, thereby destroying the interference condition and preventing a mixed and chaotic image caused by the superposition of multiple Newton rings. A feedback control module is installed on the right side of the optical cavity 7, and the right cavity mirror 82 is fixed on the feedback control module. At this time, the reflected light of the first non-polarizing beam splitter cube 30 will be reflected on the surface of the right cavity mirror, and after being reflected by the third non-polarizing beam splitter cube 32, a spot image is generated in the CCD2. The obtained spot image information is transmitted to the data processing module for analysis and processing to obtain the center coordinates of the spot image, and the center coordinates of the spot image are obtained. The coordinates are compared with the initial coordinates to obtain the error value between the two coordinates; then the data processing module sends a corresponding signal to the feedback control module according to the error value, and the feedback control module automatically drives the right cavity mirror 82 to perform angular deflection or axial movement to reduce the error value between the coordinates until the error value between the coordinates is within the preset range; finally, the center coordinates of the light spot are calculated again using the center of gravity algorithm and the Hough circle detection algorithm. When the error of the obtained center coordinates is within the set range, it is considered that the left cavity mirror 81 is coaxial with the laser beam and the optical cavity 7, and the left cavity mirror is then fixed on the optical cavity 7.

[0067] In this embodiment, the image acquisition module is a CCD industrial camera; the data processing module is an industrial computer and has built-in image analysis algorithm software, which is used to calculate the center coordinate information of the spot image; there can be multiple algorithms, including the center of gravity algorithm, the Hough circle detection algorithm, etc.; the feedback control module is an electrically controlled six-axis translation stage.

[0068] The above is only a module embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have combinations and variations of the aforementioned technical features. Without departing from the spirit and scope of the present invention, those skilled in the art can improve, modify, or replace the present invention with equivalents, or apply the structure or method of the present invention to other fields to achieve the same effect, which all fall within the scope of protection included in the present invention.

Claims

1. A gas cavity optical axis automatic adjustment system, comprising a laser generator, a cavity mirror, and an optical cavity, characterized in that: It also includes a Segnac interferometer, an adjustable aperture, and an image feedback processing structure; The laser generator is used to emit a light beam; The cavity mirror is used to be installed at the front and rear ends of the optical cavity to form a gas cavity; The Segnac interferometer is used to split the light beam emitted by the laser generator into two beams, which overlap in space and are respectively emitted into the front and rear ends of the optical cavity; The adjustable iris is used to collimate and limit the light beam in the optical path; The image feedback processing structure includes an image acquisition module, a data processing module, and a feedback control module. The image acquisition module is used to acquire a spot image formed by a light beam at a certain position in the optical path. The data processing module is used to analyze the spot image obtained by the image acquisition module and send a signal to the feedback control module based on the analysis result. The feedback control module receives the signal sent by the data processing module and adjusts the adjustable aperture or cavity mirror based on the signal. The Segnac interferometer consists of a non-polarizing beam splitter cube and a reflecting mirror.

2. The gas cavity optical axis automatic adjustment system according to claim 1, characterized in that: There are multiple image acquisition modules and feedback control modules, which are connected in a one-to-one correspondence.

3. The gas cavity optical axis automatic adjustment system according to claim 2, characterized in that: There are two image acquisition modules, which are respectively arranged at the front and rear ends of the optical cavity.

4. The gas cavity optical axis automatic adjustment system according to claim 3, characterized in that: The image acquisition module uses an industrial camera; the data processing module has a built-in image analysis algorithm for calculating the center coordinate information of the spot image; and the feedback control module uses an electrically controlled displacement platform.

5. The gas cavity optical axis automatic adjustment system according to claim 1, characterized in that: There are multiple adjustable irises, and two of them form a group.

6. The gas cavity optical axis automatic adjustment system according to any one of claims 1 to 4, characterized in that: Also included is a climbing frame, which is used to raise the optical path.

7. A method for automatically adjusting the optical axis of a gas cavity, using the automatic adjustment system for the optical axis of a gas cavity according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Start the laser generator so that the light beam emitted by the laser generator enters the Segnac interferometer, and collimates the light beam in the optical path through the first set of adjustable irises; the light beam after passing through the Segnac interferometer is divided into a reflected light beam and a transmitted light beam; and these two light beams will rotate clockwise and counterclockwise respectively, and finally return to the first non-polarizing beam splitting cube in the Segnac interferometer to couple; the reflected light beam of the first non-polarizing beam splitting cube is reflected by the second non-polarizing beam splitting cube and then enters the first image acquisition module, while the transmitted light beam of the first non-polarizing beam splitting cube is reflected by the third non-polarizing beam splitting cube and then enters the second image acquisition module; the first image acquisition module and the second image acquisition module respectively record the image information generated by the corresponding light beams, and transmit the image information to the data processing module for processing, and the center coordinates of the corresponding light spots are obtained after processing, and both are recorded as initial coordinates; S2. Install a second set of adjustable irises on both sides of the optical cavity to basically align the optical cavity and the light beam to ensure that the light beam passes through the center of the cavity. Then, fix the optical cavity and remove the second set of adjustable irises. S3. Insert an opaque metal piece into the optical cavity to prevent the light beam from penetrating the cavity, thereby destroying the interference condition and preventing the mixed and chaotic images caused by the superposition of multiple Newton rings. A feedback control module is installed on the left side of the optical cavity, and the left cavity mirror is fixed to the feedback control module. At this time, the transmitted light of the first non-polarizing beam splitter cube will be reflected on the surface of the left cavity mirror, and after being reflected by the second non-polarizing beam splitter cube, it enters the first image acquisition module to generate a spot image. The obtained spot image information is transmitted to the data processing module for analysis and processing to obtain the center coordinates of the spot image, and the center coordinates are compared with the initial coordinates to obtain the error value between the two coordinates. The data processing module then sends a corresponding signal to the feedback control module based on the error value. The feedback control module automatically drives the cavity mirror to perform angular deflection or axial movement to reduce the error value between the coordinates until the error value between the coordinates is within a preset range. Finally, the center coordinates of the light spot are calculated again using the center of gravity algorithm and the Hough circle detection algorithm. When the error of the obtained center coordinates is within the set range, the left cavity mirror is considered to be coaxial with the laser beam and the optical cavity. At this time, the left cavity mirror is fixed to the optical cavity. The adjustment and installation process of the right cavity mirror is the same.

8. The method for automatically adjusting the optical axis of a gas cavity according to claim 7, wherein: In step S1, the light beam emitted by the laser is first passed through a climbing frame to raise the optical path, and then is emitted into the Segnac interferometer.

9. The method for automatically adjusting the optical axis of a gas cavity according to claim 7, wherein: The image acquisition module is a CCD camera; the data processing module is a computer with built-in image analysis algorithm software, which is used to calculate the center coordinate information of the spot image; and the feedback control module is an electrically controlled six-axis translation stage.

Images