A device and method for detecting defects of cavity mirrors in bright and dark fields of cavity ring-down spectroscopy instrument

Abstract

A device and method for detecting defects in a cavity mirror in bright and dark fields of a cavity ring-down spectroscopy instrument. The device comprises a laser light source, an illumination optical system, a cavity mirror displacement stage, a dark field collection mirror group, a dark field detection camera, a dark field autofocus system, a bright field collection mirror group, a bright field detection camera, a bright field autofocus system, a bright and dark field image processing and defect analysis system. By rationally constructing an optical system for bright and dark field imaging and integrating the advantages of bright and dark field detection methods, the principle of bright field imaging is used to detect large defects, and dark field imaging is used to detect small defects. The two detection schemes share a set of light source and illumination system. The cavity mirror completes a scan, and the reflected light and scattered light enter two sets of collection systems respectively, so that large-scale defect information and small-scale defect information can be obtained simultaneously, thereby realizing high-precision and high-efficiency detection of cavity mirror defects ranging from hundreds of microns to submicron defects.

Description

Technical Field

[0001] The invention relates to the technical field of defect detection, and in particular to a bright-field and dark-field cavity mirror defect detection device and method for a cavity ring-down spectroscopy instrument. Background Art

[0002] Cavity ring-down spectroscopy technology uses the principle of spectral absorption to detect trace gases and is often used in trace gas detection, environmental monitoring, spectral information acquisition, resource exploration and other fields. The resonant cavity is the core component of the cavity ring-down spectroscopy instrument. It has a small volume. Resonance is established in the cavity, and spectral absorption of gas molecules occurs, achieving an absorption optical path of tens of thousands of meters. Finally, the trace gas concentration is obtained by measuring the ring-down time difference in the resonant cavity.

[0003] The establishment of resonance in the resonant cavity is based on high-precision cavity mirrors, which have high reflectivity, high surface accuracy, low defect level and other indicators to achieve resonance establishment and ring-down absorption. The defects of cavity mirrors are caused by contamination and damage to the cavity mirrors during the adjustment process, as well as the deposition of pollutants during the measurement process. Cavity mirror defects of different magnitudes, types and densities will have different effects on the resonance phenomenon, including: destroying the resonance, reducing the threshold light intensity after the resonance enhancement, and interfering with the linear shape of the ring-down curve; ultimately, they will have different degrees of impact on the measurement accuracy of the CRDS instrument.

[0004] Laparoscope defect detection is to detect the laparoscope in advance through detection equipment. It can find the reasons for the contamination and damage of the laparoscope and the decrease in positioning accuracy. The mainstream detection method is defect detection based on optical principles. When the measurement results are abnormal, it can quickly locate whether it is caused by laparoscope defects through detection. By determining the type of laparoscope defects, the particles attached to the laparoscope are cleaned, and the defective laparoscopes such as pits are replaced, thereby reducing the inspection and maintenance costs of the instrument.

[0005] The detection method of judging by human eyes and eliminating defects by experiment has the disadvantages that the magnitude of the laparoscope defects cannot be accurately judged, accurate defect information cannot be obtained, and small-size defects cannot be judged.

[0006] The bright field detection method has limited detection accuracy and it is difficult to accurately detect defects at the micron to submicron level.

[0007] White light interferometry, atomic force microscopy and other methods are usually used to detect tiny defects at the submicron level. Such solutions have low detection efficiency and high detection costs.

[0008] Optical component inspection equipment detects cavity mirror defects: Directly taking pictures with a detector camera can only determine defects of a relatively large magnitude. White light interferometry, microscopic inspection and other methods have high inspection costs, low inspection efficiency, and complex inspection processes that are prone to introduce new contamination and defects.

[0009] Bright and dark field detection methods with a larger defect detection range: It is necessary to use two lighting methods, bright field lighting and dark field lighting, respectively, and at least two scanning tests are required. It cannot meet the detection requirements of a large detection range, high detection accuracy, and detection of cavity mirror-specific defects.

[0010] In the prior art, the following prior art discloses the technical solutions for bright and dark field defect detection. The Chinese patent with the publication number "CN114264664A" and the name "A defect detection system based on bright and dark field and structured light detection" discloses a defect detection system based on bright and dark field and structured light detection. However, its design is not suitable for defect detection of high-reflectivity and high-precision cavity mirrors. Its design adopts two sets of light source solutions, bright field and dark field, which is different from the solution in this example that only one light source system realizes both bright field and dark field detection.

[0011] The existing combined bright-field and dark-field detection scheme requires implementing bright-field detection and dark-field detection in multiple steps, with low detection efficiency and a complicated process. If the defect ranges from hundreds of microns to sub-microns, it needs to be scanned by the cavity mirror multiple times, which is a complicated process.

[0012] Therefore, the existing solutions for defect detection equipment of optical components such as high-precision and high-reflectivity cavity mirrors are: high cost, low detection efficiency, complex detection process, and a small detection range of a single detection device that cannot cover the detection range of hundreds of microns to sub-microns. Summary of the invention

[0013] In order to solve the above technical problems, the present invention provides a bright and dark field cavity mirror defect detection device and method for a cavity ring-down spectroscopy instrument, which uses a light source to simultaneously shoot and detect the bright field and dark field, has low cost, high efficiency, simple detection process, and can obtain a wide range of defect information in one detection.

[0014] In order to achieve the above technical purpose, the technical solution adopted is: a bright and dark field cavity mirror defect detection device of a cavity ring-down spectroscopy instrument, comprising:

[0015] A laser light source, which is an ultraviolet light source emitting single wavelength, narrow line width, single polarization p light;

[0016] The illumination optical system receives the light beam emitted by the laser light source and emits incident light to the surface of the cavity mirror to be measured, and the angle between the incident light and the normal direction of the surface of the cavity mirror to be measured is 60°-80°;

[0017] The laparoscope displacement stage comprises a laparoscope clamping mechanism for clamping the side of the laparoscope and a laparoscope displacement mechanism for driving the laparoscope to move in the xy direction, wherein the laparoscope clamping mechanism is installed on the laparoscope displacement mechanism;

[0018] The dark field collection mirror group receives the scattered light of the cavity mirror, and its optical axis is the normal direction of the cavity mirror surface to be measured;

[0019] Dark field detection camera, which collects the scattered field image after passing through the dark field collection lens group;

[0020] The dark field autofocus system controls the surface of the cavity mirror to be measured to be located at the focal plane of the dark field collection mirror group during the movement of the cavity mirror in the xy direction;

[0021] The bright field collecting mirror group receives the reflected light from the cavity mirror, and its optical axis is the reflection direction of the incident light on the surface of the cavity mirror to be measured;

[0022] Bright field detection camera, which collects the reflected field image after passing through the bright field collection lens group;

[0023] Bright field autofocus system, which controls the surface of the cavity mirror to be measured to be located at the focal plane of the bright field collection mirror group during the movement of the cavity mirror in the xy direction;

[0024] The bright and dark field image processing and defect analysis system is connected to the dark field detection camera and the bright field detection camera, processes the collected images of the dark field detection camera and the bright field detection camera, and obtains the cavity mirror defect information.

[0025] The laparoscope displacement mechanism consists of a plane displacement mechanism and a spherical displacement mechanism. The spherical displacement mechanism is arranged above the plane displacement mechanism. The plane displacement mechanism has two mutually perpendicular linear guide rails for realizing the movement of the x-axis and the y-axis. The spherical displacement mechanism has two mutually perpendicular arc guide rails for realizing the movement of the x-axis and the y-axis.

[0026] The incident light meets the following requirements: Central wavelength stability meets the following requirements: + / -0.1nm, beam quality M 2 <1.2, the light spot pointing stability meets ±20 microradians in x and y directions for 72 hours, polarization ratio 100:1, maximum light energy: >1W.

[0027] The brightfield collection lens assembly has an integrated attenuation plate to prevent the damage threshold of the brightfield detection camera from being exceeded.

[0028] A method for detecting a bright-field and dark-field cavity mirror defect detection device of a cavity ring-down spectroscopy instrument comprises the following steps:

[0029] Step S1: installing the detection device;

[0030] Step S2: aligning and adjusting the detection device;

[0031] Step S201: the reflected light is received by the bright field collection lens group and enters the bright field detection camera for imaging, and the scattered light is received by the dark field collection lens group and enters the dark field detection camera for imaging;

[0032] Step S202: The laparoscope clamping mechanism fixes the laparoscope, and the laparoscope translation stage enables the laparoscope to scan in the xy direction;

[0033] Step S203: The bright field auto-focus system and the dark field auto-focus system ensure that the light spot on the cavity mirror surface is located in the focal plane of the bright field collection lens group and the dark field collection lens group in real time;

[0034] Step S3: image processing;

[0035] Step S301: Based on the relationship between the calibrated bright field image defect and the pixel, image processing is performed to obtain defect size information, defect type information, defect location information, etc.;

[0036] Step S302: According to the correspondence between the calibrated defects in the scattering results and the scattering dark field image, the dark field image is inverted into the actual micro defect type, equivalent defect size and clear defect position;

[0037] Step S4: stitching the bright field and dark field images scanned sequentially, classifying and counting the defect information obtained from the image processing results, and providing the position information, defect type and defect magnitude of each characteristic defect of the cavity mirror.

[0038] The dark field image defect calibration process is as follows: first, a scattering field simulation model needs to be established for each typical defect. The scattering field model is based on the BRDF theory of the corresponding defect to determine the actual collection angle and the spatial distribution of the scattering energy. Secondly, the scattering simulation model is verified through experiments to obtain the corresponding relationship between the calibrated defects and the scattered dark field image.

[0039] Corresponding image enhancement technology is introduced into the bright-field and dark-field image processing and defect analysis system to improve the detection accuracy of bright-field defects and dark-field defects.

[0040] The beneficial effects of the present invention are:

[0041] The bright and dark field cavity mirror defect detection device of the cavity ring-down spectroscopy instrument provided in the embodiment of the present invention integrates the advantages of bright field and dark field detection methods by rationally constructing the optical system of bright and dark field imaging, uses the principle of bright field imaging to detect large defects, and uses dark field imaging to detect small defects. The two detection schemes share a set of light sources and lighting systems. The cavity mirror completes a scan, and the reflected light and scattered light enter two sets of collection systems respectively, which can realize the simultaneous acquisition of large-scale defects and small-scale defect information, and realize the high-precision and high-efficiency detection of cavity mirror defects from hundreds of microns to sub-micron defects. This detection scheme combines the advantages of bright field defect detection and dark field defect detection, and realizes the detection of large-scale defects and micro defects respectively through a cavity mirror scan, thereby improving the detection accuracy and defect detection range of cavity mirror characteristic defects.

[0042] The present invention makes up for the disadvantages of judging the defects of the laparoscope by the human eye and the ring-down experiment, such as lack of consistency, poor accuracy, and random observation results. It has the advantages of being suitable for small CRDS laparoscopes, simple detection process (no need to cooperate with different detection instruments), high detection efficiency (one scan to obtain all information), high detection accuracy (dark field detection can achieve sub-micron level), and a large defect detection range (sub-micron to hundreds of micron level). It can significantly improve the detection accuracy, detection range and detection efficiency of laparoscope defects and reduce the detection cost of laparoscopes. The present invention can detect a wide range of laparoscope types. The laparoscope displacement mechanism composed of a planar displacement mechanism and a spherical displacement mechanism can detect not only planar laparoscopes but also spherical laparoscopes. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural schematic diagram of the present invention;

[0044] Figure 2 is a moving path diagram of the cavity mirror translation stage of the present invention;

[0045] Figure 3 It is a structural schematic diagram of the laparoscope displacement mechanism of the present invention;

[0046] Figure 4 is a flow chart of the method of the present invention;

[0047] Figure numerals: 1. laser light source, 2. illumination optical system, 3. cavity mirror displacement stage, 4. cavity mirror, 5. bright field collection mirror group, 6. bright field detection camera, 7. bright field autofocus system, 8. dark field collection mirror group, 9. dark field detection camera, 10. dark field autofocus system, 11. bright and dark field image processing and defect analysis system, 301. cavity mirror clamping mechanism, 302. cavity mirror displacement mechanism, 3021. plane displacement mechanism, 3022. spherical displacement mechanism. DETAILED DESCRIPTION

[0048] The preferred embodiments of the invention are given below in conjunction with the accompanying drawings to explain the technical solution of the present invention in detail. Here, the corresponding drawings are given to explain the present invention in detail. It should be particularly noted that the preferred embodiments described here are only used to illustrate and explain the present invention, and are not used to limit or restrict the present invention.

[0049] Bright field defect detection: The collection system of bright field detection is located in the reflection direction of the illumination beam, and the defect information is obtained by collecting the reflected light information of the defect. The defects detected by bright field are dark images against a bright background.

[0050] Dark field defect detection: The collection system of dark field defect detection is located in the non-reflection (scattering) direction of the illumination beam, and the collection range includes the main area of ​​scattered light distribution. By collecting the scattered light information of the defect, the magnitude of the defect is obtained. The defects detected by dark field are bright patterns against a dark background.

[0051] Conventional detection methods such as visual inspection and ring-down experiment have low detection accuracy; methods such as microscopic detection have high costs, low detection efficiency, complex detection process, and cannot obtain characteristic defect information of various levels of cavity mirrors in one detection. The embodiment of the present invention provides a bright and dark field cavity mirror defect detection device for a cavity ring-down spectroscopy instrument, which can be effectively used for high-precision identification of various characteristic defects of CRDS cavity mirrors. The device is suitable for the detection of CRDS cavity mirrors, and has the advantages of high-precision detection capability (dark field detection can achieve sub-micron level), a large defect detection range (sub-micron to hundreds of micron level), etc., which can significantly improve the detection accuracy, detection range and detection efficiency of cavity mirror defects and reduce the detection cost of cavity mirrors.

[0052] The specific scheme of the device is as follows:

[0053] like Figure 1 As shown, the device includes a laser light source 1, an illumination optical system 2, a cavity mirror displacement stage 3, a dark field collection lens group 8, a dark field detection camera 9, a dark field autofocus system 10, a bright field collection lens group 5, a bright field detection camera 6, a bright field autofocus system 7, and a bright and dark field image processing and defect analysis system 11.

[0054] The laser emitted by the laser light source 1 is a 355nm ultraviolet light source with monochromatic wavelength, narrow line width, and single polarization, and the light source must meet the requirements of pointing stability and other indicators.

[0055] The illumination optical system 2 includes: a beam expansion collimator lens group and a spot shaping lens group. The laser light source emits light that passes through the illumination optical system and then obliquely enters the surface to be measured of the cavity mirror 4. The scattered light of the cavity mirror 4 enters the dark field collection lens group 8 from the vertical direction and is finally received by the dark field detection camera 9. The reflected light of the cavity mirror 4 enters the bright field collection lens group 5 and is finally received by the bright field detection camera 6.

[0056] In this example, the reflection angle, the incident angle, and the scattering angle are all the angles between the optical axis and the normal line of the measured surface of the cavity mirror 4 .

[0057] The incident angle of the laser light source 1 can be controlled by a light source incident mechanism, and the incident angle can be adjusted within a large incident angle range. When the incident angle is large, the contrast between the background area and the defect area in the dark field detection is high, which is beneficial to the dark field detection of tiny defects.

[0058] In this example, the bright and dark field detection uses the same laser light source 1, and the angle between the incident light and the normal direction of the cavity mirror surface to be measured is 60°-80°. For example, the light source and the illumination optical system are incident at a large angle of 75°, and the bright field collection is collected at a reflection angle of 75°. The interval between the incident light and the outgoing light (reflected light) is 150°. The angular interval between the light source and the bright field collection system is large enough to meet the installation requirements of the scattered light collection system in the dark field detection. When the dark field collection scattering angle is 0°, the dark field collection lens group 8 is located in the middle of the illumination optical system and the bright field collection lens group 5.

[0059] In this example, the incident angle of the laser light source 1 and the illumination optical system 2 is fixed at 60°-80° (large angle incident). In existing dark field detection application examples, in order to ensure that the scattered energy is responded to by the detector, a smaller incident angle is selected, and a larger dark field energy collection is achieved using an ordinary light source.

[0060] In order to meet the detection requirements of both the dark field collection system and the bright field collection system, the dark field collection system installed at a 0° scattering angle needs to have a larger working distance. This working distance allows 60°-80° incident light and 60°-80° reflected light to pass through, thus meeting the requirements of bright field detection.

[0061] In this example, in order to detect micro-nano defects, the incident angle of the system light source is increased to improve the contrast between dark field defects and background, thereby satisfying the detection of submicron-level micro defects. Large angle incidence leads to weak dark field energy, so in this example, the laser light source 1 is a high-energy ultraviolet continuous wave single-bias laser, which overcomes the limitation of weak scattered collection energy of ordinary light sources in existing dark field inspections.

[0062] The ultraviolet light source selected by the laser light source 1 has greater scattered light energy than visible light and infrared laser light sources when the output power is the same in dark field detection.

[0063] The laser light source 1 uses single polarized p light, which has stronger defect expression in dark field detection than ordinary light sources. Compared with conventional laser light sources, when the incident light energy of single polarized p light is the same, the scattering efficiency is 10 of that of conventional non-polarized light. 3 Even larger. Therefore, it can meet the needs of collecting scattered light energy when the incident angle is 60°-80°.

[0064] The combined design of the laser light source system 1 and the illumination optical system 2 meets a series of energy, polarization, monochromaticity, and pointing stability requirements. The central wavelength stability meets: + / -0.1nm, beam quality M 2 <1.2, the light spot pointing stability meets ±20 microradians in x and y directions for 72 hours, polarization ratio 100:1, maximum light energy: >1W.

[0065] The incident angle of the illumination system is a fixed 60°-80° wide-angle incident angle and a 60°-80° bright field reflection collection, which can make the bright field reflection collection system and the dark field scattering collection system structure work simultaneously to meet the collection needs of a wide range of cavity mirror defects.

[0066] The laparoscope displacement stage 3 includes: a laparoscope clamping mechanism 301 and a laparoscope displacement mechanism 302. The laparoscope clamping mechanism 301 clamps the side of the laparoscope 4 to ensure that the upper and lower surfaces of the laparoscope 4 do not contact other surfaces. The laparoscope clamping mechanism 301 is installed on the laparoscope displacement mechanism 302 and is driven by the laparoscope displacement mechanism 301 to move in the x and y directions. The laparoscope displacement stage 3 completes the scanning of the entire laparoscope surface along the xy direction. The scanning path is, for example, Figure 2 The path shown realizes the scanning of the entire cavity mirror surface. The moving scanning steps of the cavity mirror displacement stage 3 are related to the spot shape. If the long axis of the spot is in the X direction and the short axis is in the Y direction, the moving step length of the cavity mirror displacement stage in the X direction is the long axis distance, and the scanning step length of the cavity mirror displacement stage in the Y direction is the short axis distance.

[0067] The dark field collection lens group 8 is placed vertically, the collection angle is the scattering direction of the incident light, the optical axis of the dark field collection lens group 8 is the normal direction of the measured surface of the cavity mirror 4, and the working distance of the dark field collection lens group 8 needs to meet the normal emission of the reflected light beam. The dark field detection camera 9 has a smaller pixel size to realize the detection of small particles, and collects the scattered field image after passing through the dark field collection lens group 8.

[0068] The dark field microscope collection lens group 8 has a high numerical aperture NA to achieve higher resolution, thereby realizing the detection of tiny defects. In the objective lens resolution formula, λ is the wavelength of the light source.

[0069]

[0070] The dark field automatic focusing system 10 needs to be adjusted in real time, so that the measured surface of the cavity mirror 4 is located at the focal plane of the dark field collection lens group 8 in real time during the movement of the cavity mirror displacement stage 3 .

[0071] The collection angle of the bright field collection lens group 5 is the reflection direction of the incident light, and the reflection angle is equal to the incident angle. The bright field collection lens group 5 is a collection lens group with normal light collection function, which is used to realize the imaging of large defects on the image plane of the bright field detection camera 6. The bright field detection camera 6 has a large pixel size and collects the reflection field image after passing through the bright field collection lens group.

[0072] The bright field automatic focusing system 7 needs to be adjusted in real time, so that the cavity mirror 4 is located at the focal plane of the bright field collection objective lens group 5 in real time during the movement of the cavity mirror displacement stage 3.

[0073] The bright and dark field image processing and defect analysis system 11 is used to process the images collected by the bright field detection camera 6 and the dark field detection camera 9 to obtain the cavity mirror defect information, and realize high-precision defect recognition and classification through image enhancement and other technologies.

[0074] Due to the enhanced design of light energy of the light source and illumination optical system in dark field detection, this example meets the light energy requirements of dark field detection. In order to ensure that the reflected light intensity does not exceed the damage threshold of the bright field detection camera, it is necessary to add an attenuation plate for the incident wavelength band of the light source to the bright field collection lens group 5. The selection of the attenuation plate is based on the energy of the light source and the damage threshold of the bright field detection camera. The bright field collection system can select attenuation plates with different attenuation levels, including OD1~OD10, or even a larger range.

[0075] The existing bright and dark field detection methods detect that the surface of the sample to be detected is mainly a planar component. The detection requirements of the laparoscope 4 in this example include both planar laparoscopes and spherical laparoscopes. However, the same type of product requires a combination of planar laparoscopes and spherical laparoscopes.

[0076] In order to meet the requirements of simultaneous detection of different types of laparoscopy, the laparoscopy displacement mechanism 302 in this example is a combination of a planar displacement mechanism 3021 and a spherical displacement mechanism 3022. Figure 3 , wherein the plane displacement mechanism 3021 is at the bottom and the spherical displacement mechanism 3022 is at the top.

[0077] When the plane cavity mirror is detected, the plane displacement mechanism 3021 realizes the movement of the x-axis and the y-axis through two vertical horizontal guide rails.

[0078] When detecting a spherical cavity mirror, the spherical displacement mechanism 3022 realizes movement of the x-axis and the y-axis through two vertical arc guide rails, the radius of the guide rail is the same as the radius of the spherical cavity mirror, and the spherical displacement mechanism 3022 can make the surface normal of the measured point of the detected spherical cavity mirror coincide with the optical axis of the dark field collection system.

[0079] like Figure 4 As shown, a method for detecting defects of a cavity mirror by a bright and dark field detection device of a cavity ring-down spectroscopy instrument specifically comprises the following steps:

[0080] Step S1: installing the detection device;

[0081] According to the above-described bright and dark field cavity mirror defect detection device of a cavity ring-down spectroscopy instrument, it is installed and corresponding devices are selected according to the indicators.

[0082] Step S2: aligning and adjusting the detection device;

[0083] Step S201: the reflected light is received by the bright field collection lens group and enters the bright field detection camera for imaging, and the scattered light is received by the dark field collection lens group and enters the dark field detection camera for imaging.

[0084] Step S202: The laparoscope clamping mechanism fixes the laparoscope, and the laparoscope translation stage enables the laparoscope to scan in the xy direction.

[0085] Step S203: The bright field auto-focus system and the dark field auto-focus system ensure that the light spot on the cavity mirror surface is located in the focal plane of the bright field collection lens group and the dark field collection lens group in real time.

[0086] Step S3: image processing;

[0087] Step S301: Based on the relationship between the calibrated bright field image defect and the pixel, image processing is performed to obtain defect size information, defect type information, defect location information, etc. 。

[0088] Step S302: Based on the correspondence between the calibrated defects in the scattering results and the scattering dark field image, the dark field image is inverted into the actual micro defect type, equivalent defect size and clear defect position.

[0089] The dark field image defect calibration process is as follows: first, a scattering field simulation model needs to be established for each typical defect. The scattering field model is based on the BRDF theory of the corresponding defect to determine the actual collection angle and the spatial distribution of the scattering energy. Secondly, the scattering simulation model is verified through experiments to obtain the corresponding relationship between the calibrated defects and the scattered dark field image.

[0090] Step S4: stitching the bright field and dark field images scanned sequentially, classifying and counting the defect information obtained from the image processing results, and providing the position information, defect type and defect magnitude of each characteristic defect of the cavity mirror.

[0091] Corresponding image enhancement technology is introduced into the bright-field and dark-field image processing and defect analysis system to improve the detection accuracy of bright-field defects and dark-field defects.

[0092] The above are only preferred embodiments of the present invention and are not intended to limit or restrict the present invention. For researchers or technicians in this field, the present invention may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection declared by the present invention.

Claims

1. A bright-field and dark-field cavity mirror defect detection device for a cavity ring-down spectroscopy instrument, characterized in that: include: A laser light source, which is an ultraviolet light source emitting single wavelength, narrow line width, single polarization p light; The illumination optical system receives the light beam emitted by the laser light source and emits incident light to the surface of the cavity mirror to be measured, and the angle between the incident light and the normal direction of the surface of the cavity mirror to be measured is 60°-80°; A laparoscope displacement stage, comprising a laparoscope clamping mechanism for clamping the side of the laparoscope and a laparoscope displacement mechanism for driving the laparoscope to move in the xy direction, the laparoscope clamping mechanism is installed on the laparoscope displacement mechanism, the laparoscope displacement mechanism is composed of a plane displacement mechanism and a spherical displacement mechanism, the spherical displacement mechanism is arranged above the plane displacement mechanism, the plane displacement mechanism has two mutually perpendicular linear guide rails for realizing the movement of the x-axis and the y-axis, and the spherical displacement mechanism has two mutually perpendicular arc guide rails for realizing the movement of the x-axis and the y-axis; The dark field collection mirror group receives the scattered light of the cavity mirror, and its optical axis is the normal direction of the cavity mirror surface to be measured; Dark field detection camera, which collects the scattered field image after passing through the dark field collection lens group; The dark field autofocus system controls the surface of the cavity mirror to be measured to be located at the focal plane of the dark field collection mirror group during the movement of the cavity mirror in the xy direction; The bright field collecting mirror group receives the reflected light from the cavity mirror, and its optical axis is the reflection direction of the incident light on the surface of the cavity mirror to be measured; Bright field detection camera, which collects the reflected field image after passing through the bright field collection lens group; Bright field autofocus system, which controls the surface of the cavity mirror to be measured to be located at the focal plane of the bright field collection mirror group during the movement of the cavity mirror in the xy direction; The bright and dark field image processing and defect analysis system is connected to the dark field detection camera and the bright field detection camera, processes the collected images of the dark field detection camera and the bright field detection camera, and obtains the cavity mirror defect information.

2. The bright-field and dark-field cavity mirror defect detection device of a cavity ring-down spectroscopy instrument according to claim 1, characterized in that: The incident light meets the following requirements: The central wavelength stability meets the following requirements: + / -0.1nm, the beam quality M 2 <1.2, the light spot pointing stability meets ±20 microradians in x and y directions for 72 hours, polarization ratio 100:1, maximum light energy: >1W.

3. The method for detecting defects using a bright-field and dark-field cavity mirror defect detection device of a cavity ring-down spectroscopy instrument according to claim 1, characterized in that: The brightfield collection lens assembly has an integrated attenuation plate to prevent the damage threshold of the brightfield detection camera from being exceeded.

4. The method for detecting defects using a bright-field and dark-field cavity mirror defect detection device of a cavity ring-down spectroscopy instrument according to claim 1, characterized in that: The specific steps include: Step S1: Installation of detection device Step S2: aligning and adjusting the detection device; Step S201: the reflected light is received by the bright field collection lens group and enters the bright field detection camera for imaging, and the scattered light is received by the dark field collection lens group and enters the dark field detection camera for imaging; Step S202: The laparoscope clamping mechanism fixes the laparoscope, and the laparoscope translation stage enables the laparoscope to scan in the xy direction; Step S203: The bright field auto-focus system and the dark field auto-focus system ensure that the light spot on the cavity mirror surface is located in the focal plane of the bright field collection lens group and the dark field collection lens group in real time; Step S3: image processing; Step S301: according to the relationship between the calibrated reflection field image defect and the pixel, image processing is performed to obtain defect size information, defect type information, and defect location information; Step S302: According to the correspondence between the calibrated defects in the scattering results and the scattering field image, the scattering field image is inverted into the actual micro-defect type, equivalent defect size and clear defect position; Step S4: stitching the reflection field and scattering field images scanned sequentially, classifying and counting the defect information obtained from the image processing results, and providing the position information, defect type and defect magnitude of each characteristic defect of the cavity mirror.

5. The method for detecting defects using a bright-field and dark-field cavity mirror defect detection device of a cavity ring-down spectroscopy instrument according to claim 4, characterized in that: The defect calibration process of the scattering field image is as follows: first, a scattering field simulation model needs to be established for each typical defect. The scattering field model is based on the BRDF theory of the corresponding defect to determine the actual collection angle and the spatial distribution of the scattering energy. Secondly, the scattering simulation model is verified through experiments to obtain the corresponding relationship between the calibrated defect and the scattering field image.

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