A triangular ring ring-down cavity automatic alignment device and method based on fast reflection mirror

Abstract

The present invention discloses a triangular ring ring-down cavity automatic alignment device and method based on a fast-reflection mirror, wherein the automatic alignment device comprises: a laser light source for generating a laser beam, an optical path mechanism for adjusting the laser beam, a fast-reflection mirror alignment lens group for aligning the tilt misalignment error and the axis displacement misalignment error of the beam adjusted by the optical path mechanism, adjusting the meridian and sagittal planes, and performing a large-range coarse adjustment and fine adjustment, a triangular ring passive resonant cavity for receiving the light beam aligned by the fast-reflection mirror alignment lens group and causing the light beam to interfere and superimpose in the passive resonant cavity, a focusing mirror for focusing and emitting the light beam emitted by the triangular ring passive resonant cavity, a detector for receiving the laser beam emitted by the focusing mirror and generating an electrical signal, and a data acquisition, recording and analysis mechanism for receiving the electrical signal of the detector and recording the ring-down time of the passive resonant cavity. The present invention can realize the automatic high-precision alignment of the cavity ring-down spectroscopy system from coarse adjustment to fine adjustment.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental trace gas detection and optical cavity ring-down spectroscopy, and in particular relates to a fast-mirror-based triangular annular ring-down cavity automatic alignment device and method. Background Art

[0002] Cavity ring-down spectroscopy (CRDS) technology is an important branch of absorption spectroscopy technology and has important application value in the field of trace gas detection. Through the use of a resonant absorption cavity, it achieves an absorption optical path of nearly 10,000 meters in a relatively small volume. The detection accuracy is ppb (part per billion) in the near-infrared band and ppt (ppt part per trillion) in the mid-infrared band. Therefore, it has the advantages of high precision, small size, and strong environmental adaptability. Cavity ring-down spectroscopy technology is used in fields that require rapid detection, such as medical diagnosis, spectral analysis, and various harsh environments, such as deep sea, atmosphere, space, etc.; it is now widely used in the field of environmental detection.

[0003] The core structure of the existing cavity ring-down spectroscopy device, the optical resonant cavity, mostly adopts a straight cavity structure. The straight cavity has advantages such as strong stability and convenient adjustment, but it has disadvantages such as inability to effectively suppress optical feedback and the existence of etalon effect. The cavity ring-down spectroscopy device using a triangular cavity effectively improves these problems, but at the same time brings problems such as complex adjustment process, low alignment accuracy, and poor stability.

[0004] The optical alignment process of the existing cavity ring-down spectroscopy system is that the first stage is to achieve the self-alignment of the cavity optical axis, and the second stage is the precise matching and alignment of the light source optical axis with the optical axis in the cavity. The quality of optical axis matching and alignment directly determines the detection accuracy of the instrument. The existing alignment steps are usually divided into two steps: coarse adjustment and fine adjustment. In the coarse adjustment link, after the alignment of the optical axis is achieved, the resonance can be initially established and the resonance phenomenon of the light intensity transition in the cavity can be detected; in the fine adjustment alignment stage, the purpose is to achieve high-precision matching of the optical axis, and manual alignment is performed synchronously by observing the length of the ring-down time. The existing installation and alignment methods have the following disadvantages: 1. During the coarse adjustment process, it is necessary to monitor the light intensity in the cavity and manually adjust the alignment mirror to achieve the alignment of the optical axis inside and outside the cavity and the preliminary establishment of the resonance phenomenon. During the manual adjustment process, the adjustment step and adjustment accuracy cannot be accurately controlled and the efficiency is low; 2. During the fine adjustment process, the alignment performance is usually measured by the length of the ring-down time. This information cannot accurately obtain the plane of the misalignment error and the adjustment direction of the plane; and in the manual fine adjustment process, a higher adjustment accuracy is required than the coarse adjustment, and the manual adjustment method is more difficult to control.

[0005] In actual applications, the existing cavity ring-down spectroscopy system may experience a loss of alignment due to changes in environmental vibration. The manual adjustment solution requires disassembly and adjustment of the machine, which has the disadvantages of low efficiency and long cycle.

[0006] Chinese patent CN109580541A discloses an optical heterodyne cavity ring-down spectrum measurement device and method, the measurement device includes a laser light source for generating a laser beam, a modulating optical path mechanism, a passive resonant cavity for receiving the laser beam modulated by the modulating optical path mechanism and interfering and superimposing the laser beam, an optical heterodyne detection mechanism for receiving the laser beam after interference superposition and generating an electrical signal, a data processing mechanism for receiving the electrical signal and judging the relationship between the electrical signal and a preset threshold value, if the electrical signal is greater than the preset threshold value, the data processing mechanism issues an instruction to shut down the laser light source and collects and draws the ring-down curve and calculates the concentration of the trace substance to be measured through a data acquisition circuit. The measurement device and method can improve the measurement accuracy, are simple to operate and low in cost. However, no solution is proposed for the alignment problem of the triangular cavity ring-down cavity.

[0007] Chinese patent CN116539281A discloses a misalignment error measuring device and a measuring method for a ring cavity ring-down spectroscopy device, wherein the measuring device comprises a laser light source, a collimation matching alignment optical path, a passive triangular resonant cavity, a focusing mirror, a detector and a data acquisition, recording and analysis mechanism arranged in sequence from the incident direction of the light source to the emitting direction of the light source; the laser light source is used to realize the emission of the light source and the scanning of the wavelength of the light source; the passive triangular resonant cavity is used to receive the energy of the light source to realize the establishment of the resonance peak, and the collimation matching alignment optical path is used to match the beam characteristics of the light source with the beam characteristics of the passive triangular resonant cavity; the detector is used to obtain the energy of the emitted light of the passive triangular resonant cavity; the data acquisition, recording and analysis mechanism is used to obtain the tilt and axis translation errors between the optical axis of the light source and the optical axis in the passive triangular resonant cavity; the passive triangular resonant cavity is also connected to a resonance establishment mechanism and a cavity length servo control mechanism, the resonance establishment mechanism is used to scan the cavity length and make the passive triangular resonant cavity meet the resonance condition, and the cavity length servo control mechanism is used to realize cavity length adjustment. However, the misalignment error acquisition scheme can only be used to indicate error information, and cannot be used to improve the adjustment efficiency of cavity ring-down spectroscopy equipment. It cannot make up for the complexity of the adjustment process, and cannot be automatically aligned after the high-precision optical path is destroyed during use.

[0008] Chinese patent CN218585094U discloses a large-stroke high-bandwidth fast-reflecting mirror structure, including a base, a connecting shaft is installed in the middle of the upper end of the base, a mirror seat is connected to the top of the connecting shaft, a reflector is installed in the middle of the upper end of the mirror seat, voice coil motor magnets are installed at the four corners of the bottom end of the mirror seat, piezoelectric ceramics are installed in the middle of the upper end of the voice coil motor magnet, a voice coil motor coil is installed at the upper end of the base facing the voice coil motor magnet, and an angular displacement sensor is installed on the upper end of the base on one side of the connecting shaft; when in use, the voice coil motor coil and the piezoelectric ceramic can push and pull the mirror seat to produce an angular rotation of the two axes, and at the same time, the angular deflection amount of the mirror seat can be measured under the action of the angular displacement sensor and fed back to the control system, and the driving control system of the external integrated control algorithm can control the driving element in a closed loop according to the angle measurement value to make the reflector realize a controllable angle deflection. However, the angle adjustment of the above-mentioned reflector is not based on the adjustment of the meridian and sagittal dual planes, and no precise control of the angle adjustment of the two planes is established, and its acquisition error is obtained through the angular position sensor. Summary of the invention

[0009] To solve the above problems, the purpose of the present invention is to provide a triangular ring ring-down cavity automatic alignment device and method based on a fast reflection mirror, which can realize automatic and high-precision alignment of the cavity ring-down spectroscopy system from coarse adjustment to fine adjustment by cooperating with a misalignment error acquisition system.

[0010] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme:

[0011] A triangular ring ring cavity automatic alignment device based on a fast reflection mirror comprises a laser light source, an optical path mechanism, a fast reflection mirror alignment lens group, a triangular ring passive resonant cavity, a focusing mirror, a detector, and a data acquisition, recording and analysis mechanism, wherein:

[0012] The laser light source is a light source for generating a laser beam;

[0013] The optical path mechanism is used to collimate, match, and split the laser beam;

[0014] The fast reflection mirror alignment mirror group is arranged between the optical path mechanism and the triangular ring passive resonant cavity, and is used to align the tilt misalignment error and the axis shift misalignment error of the light beam adjusted by the optical path mechanism, adjust the meridian and sagittal planes, and perform a large range of coarse adjustment and fine adjustment;

[0015] The triangular ring passive resonant cavity is used to receive the light beam aligned by the fast reflection mirror alignment lens group, and to cause the light beam to interfere and superimpose in the passive resonant cavity;

[0016] The focusing mirror is used to focus and emit the light beam emitted from the triangular ring passive resonant cavity;

[0017] The detector is used to receive the laser beam emitted by the focusing mirror and generate an electrical signal;

[0018] The data acquisition, recording and analysis mechanism is used to receive the electrical signal of the detector and record the passive resonant cavity ring-down time. The ring-down time is the time when the light intensity in the passive resonant cavity reaches a threshold light intensity, the laser light source is turned off, and the light intensity drops to 1 / e of the threshold light intensity. e is a mathematical constant, which is the base of the natural logarithm function.

[0019] Furthermore, the above-mentioned quick reflex mirror alignment mirror group includes a first quick reflex mirror and a second quick reflex mirror, the first quick reflex mirror and the second quick reflex mirror have the same structure, and the two are arranged in parallel and at intervals; the first quick reflex mirror includes a reflector, a mirror seat, and a base, the reflector is fixedly installed in a groove opened on the mirror seat, and the mirror seat is located above the base and arranged parallel to it; a first rigid spring support shaft, a second rigid spring support shaft, a first adjustment shaft, and a second adjustment shaft are vertically arranged between the mirror seat and the base and are uniformly distributed in sequence along the circumferential direction of the base, and a main support shaft hinged to the two is vertically arranged between the base and the center of the mirror seat.

[0020] Furthermore, the first quick reflex mirror and the second quick reflex mirror are tilted at the same angle.

[0021] Furthermore, the first adjustment shaft and the second adjustment shaft have the same structure, and are both composed of a voice coil motor and a first piezoelectric ceramic, wherein the first piezoelectric ceramic is installed in the middle of the upper end of the voice coil motor.

[0022] Furthermore, the above-mentioned optical path mechanism includes a collimating lens group, a matching lens group, and a beam splitter, and the collimating lens group, the matching lens group, and the beam splitter are sequentially arranged on the output optical axis of the laser light source.

[0023] Furthermore, the above-mentioned triangular ring passive resonant cavity includes an input coupling mirror, an output coupling mirror, and a spherical mirror located in the cavity, the input coupling mirror and the output coupling mirror of the planar structure are located at the top of the cavity, the spherical mirror is arranged at the bottom of the cavity through a second piezoelectric ceramic, and the optical path between the input coupling mirror, the output coupling mirror, and the spherical mirror forms a closed optical axis loop of the triangular cavity; the cavity has an air inlet and an air outlet, and a gas filter is arranged at the air inlet.

[0024] Furthermore, the spherical mirror is connected to a cavity length servo control mechanism for adjusting the distance between the spherical mirror and the input coupling mirror and the output coupling mirror.

[0025] Furthermore, the optical path mechanism is connected to an automatic misalignment error acquisition system for performing frequency sweep comparison between the mode characteristics of the light in the triangular ring passive resonant cavity and the light source light, and providing the plane and type of misalignment error in the triangular ring passive resonant cavity.

[0026] Furthermore, the above-mentioned automatic misalignment error acquisition system and the quick-reflection mirror alignment lens group are connected to a main control system, and the main control system is used to transmit the alignment method of the misalignment error to the quick-reflection mirror alignment lens group.

[0027] A method for aligning and adjusting a triangular ring ring-down cavity based on a fast-reflection mirror comprises the following steps:

[0028] S1. Make the optical path of the triangular ring passive resonant cavity meet the closed optical axis characteristic: the laser light source emits a laser beam incident on the input coupling mirror in the triangular ring passive resonant cavity, and then is reflected again by the output coupling mirror, the reflected light is incident on the spherical mirror and reflected back to the input coupling mirror by the original path, and finally emitted out of the cavity by the output coupling mirror to form an initial ring-down optical cavity; the cavity length, cavity angle and curvature of the spherical mirror in the closed optical axis loop of the triangular ring passive resonant cavity are designed to meet the resonant cavity stability condition and the closed optical axis condition;

[0029] S2, the laser light source emits a laser beam which is collimated, matched, and split through an optical path mechanism, and then manually adjusted through a fast-reflection mirror to align the lens group, so that the adjusted light path of the light source is preliminarily aligned with the light path of the triangular ring passive resonant cavity;

[0030] S3, the voice coil motor in the mirror group is roughly adjusted with a fast reflection mirror, and the resonance phenomenon is initially established in coordination with the cavity length servo control mechanism connected to the spherical mirror; the detector observes the transition of light intensity in the triangular ring passive resonant cavity;

[0031] S4. After establishing the threshold light intensity, the ring-down events are scanned; the frequency domain characteristics of the light in the triangular ring passive resonant cavity and the laser light source are compared by automatically acquiring the system frequency through the offset error, and the plane and offset type of the offset error are obtained;

[0032] S5. After obtaining the error information, the main control system controls the quick reflex mirror to align with the first piezoelectric ceramic in the first adjustment axis in the mirror group to achieve tilt alignment in the meridian plane, and controls the first piezoelectric ceramic in the second adjustment axis to achieve tilt alignment in the sagittal plane; the first quick reflex mirror and the second quick reflex mirror are tilted at the same angle to achieve alignment of the axis shift error.

[0033] Furthermore, the above-mentioned fast-mirror-based triangular ring ring-down cavity adjustment and alignment method further includes:

[0034] Step S6: If the optical path is damaged during use, it is necessary to enter step S4 again to read the magnitude of the misalignment error and make a judgment; if resonance cannot be established during the scanning adjustment of the voice coil motor, it is judged to be destructive damage and requires manual adjustment, then enter step S2; if resonance is established again during the scanning process, it is judged to be general damage, return to step S4, and re-enter the fine adjustment step.

[0035] Due to the adoption of the above-mentioned technical solution, the present invention has the following advantages:

[0036] The triangular annular ring-shaped ring-down cavity automatic alignment device based on a fast-reflection mirror realizes rapid establishment of a resonance phenomenon through a large-stroke shaft shift mechanism in a coarse adjustment stage, and cooperates with a misalignment error automatic acquisition system in a fine adjustment stage to obtain misalignment error information of two orthogonal planes in real time, and cooperates with first and second fast-reflection mirrors to realize alignment of tilt and shaft shift misalignment errors of two respective planes, the meridian and sagittal, and realize optimal establishment of the ring-down time; cooperates with the misalignment error automatic acquisition system to realize automatic alignment of the misalignment error, and effectively solves the problem that the existing manual alignment scheme is inefficient and cannot realize automatic alignment; in the machine assembly stage, in the re-assembly process after the optical axis is damaged, there is no need to disassemble the machine, and the optical axis can be automatically aligned. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of the automatic alignment device of the triangular annular ring-down cavity based on the fast reflection mirror of the present invention;

[0038] Figure 2 yes Figure 1 A main structural diagram of the middle fast reflex mirror aiming at the first fast reflex mirror of the mirror group;

[0039] Figure 3 yes Figure 1 A top view of the structure of the middle fast reflex mirror aligned with the first fast reflex mirror of the mirror group;

[0040] Figure 4 It is a flow chart of the method for arranging and aligning a triangular ring ring-down cavity based on a fast-reflection mirror of the present invention;

[0041] In the figure: 1-laser light source; 2-optical path mechanism; 3-fast reflex mirror alignment lens group; 4-triangular ring passive resonant cavity; 5-focusing mirror; 6-detector; 7-data acquisition, recording and analysis mechanism; 8-cavity length servo control mechanism; 9-automatic acquisition system for offset error; 10-main control system; 3.1-first fast reflex mirror; 3.2-second fast reflex mirror; 3.11-reflecting mirror; 3.12-mirror seat; 3.13-first rigid spring support shaft; 3.14-main support shaft; 3.15-first adjustment shaft; 3.16-base; 3.17-second adjustment shaft; 3.151-voice coil motor; 3.152-first piezoelectric ceramic; 4.1-input coupling mirror; 4.2-output coupling mirror; 4.3-spherical mirror; 4.4-second piezoelectric ceramic; 4.5-air inlet; 4.6-gas filter; 4.7-air outlet. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0043] like Figure 1 , 2 As shown in , 3, a triangular ring ring-down cavity automatic alignment device based on a fast reflection mirror comprises a laser light source, an optical path mechanism, a fast reflection mirror alignment lens group, a triangular ring passive resonant cavity, a focusing mirror, a detector, and a data acquisition, recording and analysis mechanism, wherein:

[0044] The laser light source 1 is a light source for generating a laser beam, and the wavelength tuning range includes the characteristic absorption spectrum of the target detection gas;

[0045] The optical path mechanism 2 includes a collimating lens group, a matching lens group, and a beam splitter. The collimating lens group, the matching lens group, and the beam splitter are sequentially arranged on the output optical axis of the laser light source, and are used to collimate, match, and split the laser light beam to achieve feature matching between the laser light beam and the light beam in the triangular annular passive resonant cavity; wherein the beam splitter is connected to an automatic misalignment error acquisition system 9, and the beam splitter is used to cooperate with the automatic misalignment error acquisition system to obtain misalignment error information in the meridian and sagittal planes, and the automatic misalignment error acquisition system is used to perform frequency scanning comparison of the mode characteristics of the light in the triangular annular passive resonant cavity and the light source light, and provide the plane and type of the misalignment error in the triangular annular passive resonant cavity;

[0046] The fast reflection mirror alignment mirror group 3 is arranged between the optical path mechanism 2 and the triangular ring passive resonant cavity 4, and is used to align the tilt misalignment error and the axis shift misalignment error of the light beam adjusted by the optical path mechanism, adjust the meridian and sagittal planes, and perform a large range of coarse adjustment and fine adjustment;

[0047] The triangular ring passive resonant cavity 4 is used to receive the light beam aligned by the fast reflection mirror alignment lens group 3, and to cause the light beam to interfere and superimpose in the passive resonant cavity;

[0048] The focusing mirror 5 is used to focus and emit the outgoing light beam of the triangular ring passive resonant cavity 4;

[0049] The detector 6 is used to receive the laser beam emitted by the focusing mirror 5 and generate an electrical signal;

[0050] The data acquisition, recording and analysis mechanism 7 is used to receive the electrical signal of the detector 6 and record the passive resonant cavity ring-down time. The ring-down time is the time when the light intensity in the passive resonant cavity reaches a threshold light intensity, the laser light source is turned off, and the light intensity drops to 1 / e of the threshold light intensity. e is a mathematical constant, which is the base of the natural logarithm function.

[0051] In order to reflect the structure of the first adjustment shaft 3.15 and the second adjustment shaft 3.17, Figure 3 The reflector and the mirror mount are not shown. Figure 2 , 3As shown, the above-mentioned quick reflex mirror alignment lens group 3 includes a first quick reflex mirror 3.1 and a second quick reflex mirror 3.2. The first quick reflex mirror and the second quick reflex mirror have the same structure and are parallel and spaced apart. The first quick reflex mirror 3.1 is used for aligning the tilt misalignment error and includes a reflector 3.11, a mirror seat 3.12 and a base 3.16. The reflector 3.11 is fixedly mounted in a groove provided on the mirror seat 3.12. The mirror seat 3.12 is located above the base 3.16 and is arranged parallel to it. A first rigid spring support shaft 3.13, a second rigid spring support shaft 3.18, a first adjustment shaft 3.15 and a second adjustment shaft 3.17 are vertically arranged between the mirror seat and the base and are uniformly spaced apart in sequence along the circumferential direction of the base. A main support shaft 3.14 hinged to the two is vertically arranged between the base and the center of the mirror seat. The above-mentioned main support shaft, the first rigid spring support shaft and the second rigid spring support shaft play a supporting role. The above-mentioned first adjustment shaft and the second adjustment shaft respectively realize the adjustment of the meridian and sagittal planes.

[0052] The first fast reflection mirror 3.1 and the second fast reflection mirror 3.2 are tilted in the same direction and at the same angle, and are used for aligning the axis shift misalignment error.

[0053] The above-mentioned first adjustment axis 3.15 and second adjustment axis 3.17 have the same structure, and are both composed of a voice coil motor 3.151 and a first piezoelectric ceramic 3.152. The first piezoelectric ceramic 3.152 is installed in the middle of the upper end of the voice coil motor 3.151; the above-mentioned voice coil motor and first piezoelectric ceramic can push and pull the mirror seat 3.12 to make it tilt at an angle, wherein the voice coil motor realizes a large range of coarse adjustment to quickly establish a resonance phenomenon; the piezoelectric ceramic realizes high-precision fine adjustment to increase the light intensity threshold in the triangular ring passive resonant cavity, increase the ring-down time, and improve the system accuracy of the cavity ring-down system.

[0054] The above-mentioned triangular ring passive resonant cavity 4 includes an input coupling mirror 4.1, an output coupling mirror 4.2, and a spherical mirror 4.3 located in the cavity. The input coupling mirror and the output coupling mirror of the planar structure are located at the top of the cavity, and the spherical mirror is arranged at the bottom of the cavity through the second piezoelectric ceramic 4.4. The optical path among the input coupling mirror, the output coupling mirror and the spherical mirror forms a triangular cavity closed optical axis loop; the cavity has an air inlet 4.5 and an air outlet 4.7, and a gas filter 4.6 is arranged at the air inlet. During detection, the gas to be detected is introduced from the air inlet 4.5 on the triangular ring passive resonant cavity 4 and discharged from the air outlet 4.7; the spherical mirror is connected to a cavity length servo control mechanism 8 for adjusting the distance between the spherical mirror and the input coupling mirror and the output coupling mirror; the optical path of the triangular ring passive resonant cavity controls the second piezoelectric ceramic via the cavity length servo control mechanism to achieve cavity length adjustment, thereby satisfying the longitudinal mode matching condition to achieve resonance.

[0055] The above-mentioned misalignment error automatic acquisition system 9 and the quick-reflection mirror alignment lens group 3 are connected to the main control system 10, and the main control system is used to transmit the alignment method of the misalignment error to the quick-reflection mirror alignment lens group.

[0056] like Figure 4 As shown, a method for aligning and adjusting a triangular ring ring-down cavity based on a fast reflection mirror comprises the following steps:

[0057] S1. Make the optical path of the triangular ring passive resonant cavity meet the closed optical axis characteristic: the laser light source 1 emits a laser beam incident on the input coupling mirror 4.1 in the triangular ring passive resonant cavity 4, and then is reflected again by the output coupling mirror 4.2, the reflected light is incident on the spherical mirror 4.3 and reflected back to the input coupling mirror by the original path, and finally emitted out of the cavity by the output coupling mirror to form an initial ring-down optical cavity; the cavity length, cavity angle and curvature of the spherical mirror in the closed optical axis loop of the triangular ring passive resonant cavity are designed to meet the resonant cavity stability condition and the closed optical axis condition;

[0058] S2, the laser light source 1 emits a laser beam which is collimated, matched, and split through the optical path mechanism 2, and then the quick reflection mirror alignment lens group 3 is manually adjusted to perform preliminary alignment, so that the adjusted light path of the light source is preliminarily aligned with the light path of the triangular ring passive resonant cavity 4;

[0059] S3, the voice coil motor 3.151 in the mirror group 3 is roughly adjusted by a fast reflection mirror, and the cavity length servo control mechanism 8 connected to the spherical mirror 4.3 is coordinated to achieve the initial establishment of the resonance phenomenon; the detector 6 observes the transition of the light intensity in the triangular ring passive resonant cavity 4;

[0060] S4. After establishing the threshold light intensity, the ring-down events are scanned; the frequency domain characteristics of the light in the triangular ring passive resonant cavity 4 and the light of the laser light source 1 are compared by the automatic acquisition system 9 for the offset error, and the plane and the offset type with the offset error are obtained;

[0061] S5, after obtaining the error information in step S4, the main control system 10 controls the quick reflex mirror to align with the first piezoelectric ceramic in the first adjustment shaft 3.15 in the mirror group 3 to achieve the tilt alignment of the meridian plane; similarly, the first piezoelectric ceramic in the second adjustment shaft 3.17 is used to achieve the tilt alignment of the sagittal plane; the first quick reflex mirror and the second quick reflex mirror are tilted at the same angle to achieve the alignment of the axis shift error;

[0062] Step S6: If the optical path is damaged during use, it is necessary to enter step S4 again to read the magnitude of the misalignment error and make a judgment; if resonance cannot be established during the scanning adjustment of the voice coil motor, it is judged to be destructive damage and requires manual adjustment, then enter step S2; if resonance is established again during the scanning process, it is judged to be general damage, return to step S4, and re-enter the fine adjustment step.

[0063] The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Without departing from the spirit and scope of the present invention, all equivalent changes and modifications made within the scope of the patent application of the present invention shall fall within the scope of patent protection of the present invention.

Claims

1. An automatic alignment device for a triangular ring ring-down cavity based on a fast-reflection mirror, characterized in that: It includes a laser light source, an optical path mechanism, a fast reflection mirror alignment lens group, a triangular ring passive resonant cavity, a focusing mirror, a detector, and a data acquisition, recording and analysis mechanism, among which: The laser light source is a light source for generating a laser beam; The optical path mechanism is used to collimate, match, and split the laser beam; the optical path mechanism includes a collimating lens group, a matching lens group, and a beam splitter, and the collimating lens group, the matching lens group, and the beam splitter are sequentially arranged on the output optical axis of the laser light source; the optical path mechanism is connected to an automatic misalignment error acquisition system, which is used to perform frequency sweeping comparison on the mode characteristics of the light in the triangular ring passive resonant cavity and the light source light, and to provide the plane and type of the misalignment error in the triangular ring passive resonant cavity; the automatic misalignment error acquisition system and the fast reflection mirror alignment lens group are connected to the main control system, and the main control system is used to transmit the alignment method of the misalignment error to the fast reflection mirror alignment lens group; The quick reflex mirror alignment mirror group is arranged between the optical path mechanism and the triangular ring passive resonant cavity, and is used for aligning the tilt misalignment error and the axis shift misalignment error, adjusting the meridian and sagittal planes, and performing large-range coarse adjustment and fine adjustment on the light beam adjusted by the optical path mechanism; the quick reflex mirror alignment mirror group includes a first quick reflex mirror and a second quick reflex mirror, the first quick reflex mirror and the second quick reflex mirror have the same structure, are arranged in parallel and at intervals, and are arranged at the same angle; the first quick reflex mirror includes a reflector, a mirror seat, and a base, the reflector is fixedly installed in a groove provided on the mirror seat, the mirror seat is located above the base and is arranged parallel to the base; a first rigid spring support shaft, a second rigid spring support shaft, a first adjustment shaft, and a second adjustment shaft are vertically arranged between the mirror seat and the base, and a main support shaft hinged to the two is vertically arranged at the center of the base and the mirror seat; the first adjustment shaft and the second adjustment shaft have the same structure, and are both composed of a voice coil motor and a first piezoelectric ceramic, and the first piezoelectric ceramic is installed in the middle of the upper end of the voice coil motor; The triangular ring passive resonant cavity is used to receive a light beam aligned by a fast reflection mirror alignment mirror group, and interfere and superimpose the light beam in the passive resonant cavity; the triangular ring passive resonant cavity comprises an input coupling mirror, an output coupling mirror, and a spherical mirror located in the cavity, the input coupling mirror and the output coupling mirror are planar structures and are located at the top of the cavity, the spherical mirror is arranged at the bottom of the cavity through a second piezoelectric ceramic, and the optical path between the input coupling mirror, the output coupling mirror, and the spherical mirror forms a triangular cavity closed optical axis loop; the cavity has an air inlet and an air outlet, and a gas filter is arranged at the air inlet; the spherical mirror is connected to a cavity length servo control mechanism, which is used to adjust the distance between the spherical mirror and the input coupling mirror and the output coupling mirror; The focusing mirror is used to focus and emit the light beam emitted from the triangular ring passive resonant cavity; The detector is used to receive the laser beam emitted by the focusing mirror and generate an electrical signal; The data acquisition, recording and analysis mechanism is used to receive the electrical signal of the detector and record the passive resonant cavity ring-down time. The ring-down time is the time when the light intensity in the passive resonant cavity reaches a threshold light intensity, the laser light source is turned off, and the light intensity drops to 1 / e of the threshold light intensity. e is a mathematical constant, which is the base of the natural logarithm function.

2. A method for aligning a triangular ring ring-down cavity based on a fast-reflection mirror, which is implemented by using the triangular ring ring-down cavity automatic alignment device based on a fast-reflection mirror according to claim 1, and is characterized by: It includes the following steps: S1. Make the optical path of the triangular ring passive resonant cavity meet the closed optical axis characteristic: the laser light source emits a laser beam incident on the input coupling mirror in the triangular ring passive resonant cavity, and then is reflected again by the output coupling mirror, the reflected light is incident on the spherical mirror and reflected back to the input coupling mirror by the original path, and finally emitted out of the cavity by the output coupling mirror to form an initial ring-down optical cavity; the cavity length, cavity angle and curvature of the spherical mirror in the closed optical axis loop of the triangular ring passive resonant cavity are designed to meet the resonant cavity stability condition and the closed optical axis condition; S2, the laser light source emits a laser beam which is collimated, matched, and split through an optical path mechanism, and then manually adjusted through a fast-reflection mirror to align the lens group, so that the adjusted light path of the light source is preliminarily aligned with the light path of the triangular ring passive resonant cavity; S3, use the fast reflection mirror to make a large stroke coarse adjustment on the voice coil motor in the mirror group, and cooperate with the cavity length servo control mechanism connected to the spherical mirror to initially establish the resonance phenomenon; The detector observed the transition of light intensity in the triangular ring passive resonant cavity; S4. After establishing the threshold light intensity, the ring-down events are scanned; the frequency domain characteristics of the light in the triangular ring passive resonant cavity and the laser light source are compared by automatically acquiring the system frequency through the offset error, and the plane and offset type of the offset error are obtained; S5. After obtaining the error information, the main control system controls the quick reflex mirror to align with the first piezoelectric ceramic in the first adjustment axis in the mirror group to achieve tilt alignment in the meridian plane, and controls the first piezoelectric ceramic in the second adjustment axis to achieve tilt alignment in the sagittal plane; the first quick reflex mirror and the second quick reflex mirror are tilted at the same angle to achieve alignment of the axis shift error.

3. The method for aligning and adjusting a triangular ring ring-down cavity based on a fast-reflection mirror according to claim 2 is characterized by: It also includes: Step S6: If the optical path is damaged during use, it is necessary to enter step S4 again to read the magnitude of the misalignment error and make a judgment; if resonance cannot be established during the scanning adjustment of the voice coil motor, it is judged as destructive damage and requires manual adjustment, then enter step S2; if resonance is established again during the scanning process, it is judged as general damage, return to step S4, and re-enter the fine adjustment step.

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