OCT (Optical Coherence Tomography) measuring system and measuring method

Abstract

The OCT measuring system comprises a light source unit, a reference arm light path unit, a sample arm light path unit, a spectrograph, a preview camera and a computer, and the light source unit comprises a light source, an optical fiber circulator and a coupler; the reference arm light path unit comprises a first collimator and a reflector; the sample arm light path unit comprises a second collimator scanning galvanometer, a dichroscope, a scanning lens and a sample table, the scanning path of the scanning galvanometer is accurately controlled, the light path direction is flexibly adjusted, light spots can be subjected to two-dimensional scanning on the surface of a sample, and the detection accuracy is improved. The long-wave-pass dichroscope is superposed between the scanning galvanometer and the scanning lens, so that the optical path of the preview camera and the optical path of the OCT are coaxial, the system structure is simplified, the view field of the preview camera is prevented from being limited by the movement of the scanning galvanometer, and the measurement flexibility and the measurement efficiency are improved.

Description

Technical Field

[0001] The present application relates to optical detection technology, and in particular to an OCT measurement system and a measurement method. Background Art

[0002] Optical coherence tomography (OCT) is an advanced imaging technology based on the principle of weak coherent light interference. It detects the back reflection or scattering signals of incident weak coherent light at different depths of biological tissues and generates two-dimensional or three-dimensional structural images of biological tissues after scanning and processing.

[0003] As an advanced non-destructive testing technology, OCT has shown great application potential and broad development prospects in many fields such as medicine and materials science. With the continuous innovation of technology and the continuous expansion of application fields, OCT technology will play a more important and extensive role in the future.

[0004] Although OCT, as a cutting-edge imaging technology, has demonstrated excellent performance in many fields, it still faces some challenges and limitations in its actual application. Among them, a notable problem is that the precise placement of the focal plane is crucial to the measurement results. Once the placement is inaccurate, measurement errors may be introduced, reducing the reliability of the data. In addition, sample positioning is also a major challenge. If the sample is not properly placed in the scanning field of view, or the process of determining the position of the sample takes too long, it will directly affect the efficiency and experience of OCT use. These problems often require the precise operation and rich experience of professional operators to solve, which increases the requirements for the operator's skill level. Summary of the invention

[0005] In view of this, it is necessary to provide an OCT measurement system and its preparation method that can improve measurement efficiency and flexibility to address the technical defects of the current OCT measurement system, such as inaccurate focal plane positioning, time-consuming sample positioning, and low efficiency of large-range scanning.

[0006] To solve the above problems, this application adopts the following technical solutions:

[0007] One of the purposes of the present application is to provide an OCT measurement system, comprising: a light source unit (110), a reference arm optical path unit (120), a sample arm optical path unit (130), a spectrometer (140), a preview camera (150) and a computer (160), wherein:

[0008] The light source unit (110) comprises a light source (111), an optical fiber circulator (112) and a coupler (113);

[0009] The reference arm optical path unit (120) comprises a first collimator (121) and a reflector (123);

[0010] The sample arm optical path unit (130) comprises a second collimator (131), a scanning galvanometer (132), a dichroic mirror (133), a scanning lens (134) and a sample stage (135);

[0011] The laser beam emitted by the light source (111) passes through the optical fiber circulator (112) to achieve unidirectional transmission and isolation of the optical path, and then passes through the coupler (113) to be divided into reference light and sample light;

[0012] The reference light is collimated by the first collimator (121) and then incident on the reflector (123). After being reflected by the reflector (123), the reference light sequentially passes through the first collimator (121), the coupler (113) and the optical fiber circulator (112) and is then acquired by the spectrometer (140);

[0013] The sample light is converted into parallel light by the second collimator (131) and then enters the scanning galvanometer (132). After being scanned by the scanning galvanometer (132), the sample light enters the dichroic mirror (133) and then is focused on the sample located on the sample stage (135) by the scanning lens (134), and excites the sample to generate backscattered light. The backscattered light is sequentially passed through the scanning lens (134), the dichroic mirror (133), the scanning galvanometer (132), the second collimator (131) and the optical fiber circulator (112) and then is acquired by the spectrometer (140);

[0014] The spectrometer (140) performs OCT imaging based on the acquired light signal and the image is acquired by the computer (160). The computer (160) drives the sample stage (135) to perform a z-direction lifting and lowering movement relative to the scanning lens (134) and automatically triggers the preview camera (150) to capture a current image of the sample stage (135) after each displacement, and records the movement distance of the sample stage (135) in real time. The computer (160) is also used to analyze the received corresponding image to determine the clearest focusing position of the sample, i.e., the best focusing state, and control the sample stage (135) to move to this position.

[0015] In some embodiments, the computer (160) is further used to restart the preview camera (150) to capture images after the sample is in the optimal focus state, and detect the position of the sample in the preview camera (150) using image processing technology to obtain ROI;

[0016] The computer (160) calculates the control amount of the scanning galvanometer (132) corresponding to the pixel position of the ROI according to a mapping table between the preview camera (150) and the scanning galvanometer (132).

[0017] In some embodiments, the computer (160) controls the movement of the sample stage (135) and calculates the displacement of the sample stage (135) and the corresponding image quality score curve to obtain the valley value of the curve, and then controls the sample stage (135) to move there;

[0018] The computer (160) determines whether there is a sample within the calibrated field of view of the preview camera (150), and if so, proceeds to the next step; if not, moves the sample stage (135) to the calibrated field of view, and then proceeds to the next step;

[0019] The user selects the ROI in the field of view or obtains the maximum circumscribed rectangle or circumscribed circle of the sample as the ROI;

[0020] The computer (160) calculates the control amount of the scanning galvanometer (132) corresponding to the pixel position of the ROI according to the calibration mapping table between the preview camera (150) and the scanning galvanometer (132), and generates a scanning waveform corresponding to the ROI pixel area according to the mapping table to obtain an ROI image.

[0021] In some of the embodiments, a calibration plate is provided at the OCT focus position, and the sample stage (135) is fine-tuned to make the calibration plate horizontal, and the calibration plate is scanned to obtain an OCT image of the calibration plate. After the scanning is completed, a picture of the calibration plate currently held by the preview camera (150) is captured, and point feature extraction and matching are performed on the calibration plate OCT image and the picture of the calibration plate currently held by the preview camera (150), and the relationship between the pixels of the preview camera (150) and the control amount of the scanning galvanometer (132) is calculated to obtain the calibration mapping table.

[0022] In some embodiments, the calibration plate includes a checkerboard calibration plate or a circular calibration plate.

[0023] In some of the embodiments, the spectrometer (140) converts the acquired light signal into the OCT image through an OCT image reconstruction algorithm based on the acquired light signal, and the OCT image can extract sample 3D point cloud data.

[0024] In some of the embodiments, the dispersion compensator (122) is further provided on the optical path from the first collimator (121) to the reflector (123) to compensate for the dispersion effect generated when the laser is transmitted in the optical fiber.

[0025] In some of the embodiments, an illumination LED (136) is further provided in the optical path from the dichroic mirror (133) to the sample stage (135).

[0026] In some of the embodiments, the computer (160) is also connected to a data control acquisition card (161), and the data control acquisition card (161) is electrically connected to the preview camera (150), the sample stage (135), the scanning galvanometer (132) and the spectrometer (140); the computer (160) is also electrically connected to the light source (111), and the light source (111) is a superluminescent diode.

[0027] The second object of the present application is to provide an OCT measurement method of the OCT measurement system, comprising the following steps:

[0028] The laser beam emitted by the light source (111) passes through the optical fiber circulator (112) to achieve unidirectional transmission and isolation of the optical path, and then passes through the coupler (113) to be divided into reference light and sample light;

[0029] The reference light is collimated by the first collimator (121) and then incident on the reflector (123). After being reflected by the reflector (123), the reference light sequentially passes through the first collimator (121), the coupler (113) and the optical fiber circulator (112) and is then acquired by the spectrometer (140);

[0030] The sample light is converted into parallel light by the second collimator (131) and then enters the scanning galvanometer (132). After being scanned by the scanning galvanometer (132), the sample light enters the dichroic mirror (133) and then is focused on the sample located on the sample stage (135) by the scanning lens (134), and excites the sample to generate backscattered light. The backscattered light is sequentially passed through the scanning lens (134), the dichroic mirror (133), the scanning galvanometer (132), the second collimator (131) and the optical fiber circulator (112) and then is acquired by the spectrometer (140);

[0031] The spectrometer (140) performs OCT imaging based on the acquired light signal and the image is acquired by the computer (160). The computer (160) drives the sample stage (135) to perform a z-direction lifting and lowering movement relative to the scanning lens (134) and automatically triggers the preview camera (150) to capture a current image of the sample stage (135) after each displacement, and records the movement distance of the sample stage (135) in real time. The computer (160) is also used to analyze the received corresponding image to determine the clearest focusing position of the sample, i.e., the best focusing state, and control the sample stage (135) to move to this position.

[0032] This application adopts the above technical solution, and its beneficial effects are as follows:

[0033] The OCT measurement system and measurement method provided by the present application, the laser beam emitted by the light source (111) passes through the optical fiber circulator (112) to realize unidirectional transmission and isolation of the optical path, and then passes through the coupler (113) to be divided into reference light and sample light, the reference light is collimated by the first collimator (121) and then enters the reflector (123), and after being reflected by the reflector (123), it passes through the first collimator (121), the coupler (113) and the optical fiber circulator (112) in sequence and is then acquired by the spectrometer (140), the sample light is converted into parallel light by the second collimator (131) and then enters the scanning galvanometer (132), and after being scanned by the scanning galvanometer (132), it enters the dichroic mirror (133) and then is focused on the sample located on the sample stage (135) by the scanning lens (134) and excites the sample to generate backscattered light. The backscattered light is emitted by the scanning lens (134), the dichroic mirror (133), the scanning galvanometer (132), the second collimator (131) and the optical fiber circulator (112) and then acquired by the spectrometer (140). The spectrometer (140) performs OCT imaging according to the acquired optical signal and acquires the image by the computer (160). The present application achieves flexible adjustment of the direction of the optical path by accurately controlling the scanning path of the scanning mirror, so that the light spot can perform two-dimensional scanning on the sample surface. Since a long-wave dichroic mirror (133) is superimposed between the scanning galvanometer (132) and the scanning lens (134), the optical path of the preview camera (150) and the OCT optical path are coaxial, thereby simplifying the system structure, avoiding the field of view of the preview camera (150) being restricted by the movement of the scanning galvanometer (132), and improving the measurement flexibility and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is a schematic diagram of the structure of the OCT measurement system provided in Example 1 of the present application.

[0036] Figure 2 It is a schematic diagram of the principle of the OCT measurement system provided in Example 1 of the present application.

[0037] Figure 3 This is a sample measurement flow chart provided in Example 1 of the present invention.

[0038] Figure 4It is a flowchart of the steps of the OCT measurement method provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0039] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0040] In the description of the present application, it should be understood that the terms "upper", "lower", "horizontal", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0042] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0043] Example 1

[0044] See also Figure 1 and Figure 2 , is a schematic diagram of the structure of the OCT measurement system provided in the embodiment of the present application, including a light source unit 110, a reference arm optical path unit 120, a sample arm optical path unit 130, a spectrometer 140, a preview camera 150 and a computer 160. The technical solution implemented is described in detail below.

[0045] The light source unit 110 includes a light source 111 , a fiber circulator 112 , and a coupler 113 .

[0046] In this embodiment, the light source 111 uses SLD (super luminescent diode) as the light source. The laser beam emitted by the light source 111 can achieve unidirectional transmission and isolation of the optical path through the optical fiber circulator 112. The coupler 113 is used to divide the incident laser beam into the reference arm optical path and the sample arm optical path according to the proportion.

[0047] The reference arm optical path unit 120 includes a first collimator 121 and a reflecting mirror 123 .

[0048] In this embodiment, the dispersion compensator 122 is also provided on the optical path from the first collimator 121 to the reflector 123 to compensate for the dispersion effect generated when the laser is transmitted in the optical fiber, thereby ensuring the coherence between the reference light and the sample light, thereby improving the clarity and accuracy of the interference signal.

[0049] The sample arm optical path unit 130 includes a second collimator 131 , a scanning galvanometer 132 , a dichroic mirror 133 , a scanning lens 134 and a sample stage 135 .

[0050] The computer 160 is electrically connected to the light source 111 , the scanning galvanometer 132 , the sample stage 135 , the spectrometer 140 and the preview camera 150 (preview camera).

[0051] It is understood that the computer 160 can adjust the wavelength and frequency of the light source 111. The computer 160 can precisely control the scanning path of the scanning galvanometer 132 to achieve flexible adjustment of the light path direction, so that the light spot can perform two-dimensional scanning on the sample surface. The computer 160 can drive the sample stage 135 to perform precise z-direction lifting and lowering motion relative to the scanning lens 134, and after each displacement, automatically trigger the preview camera 150 to capture the current sample stage image and record the movement distance of the sample stage 135 in real time. The computer 160 can obtain imaging information from the spectrometer 140.

[0052] In this embodiment, the computer 160 is connected to a data control and acquisition card 161 , and the data control and acquisition card 161 is electrically connected to the preview camera 150 , the sample stage 135 , the scanning galvanometer 132 , and the spectrometer 140 .

[0053] In this embodiment, an illumination LED 136 is further provided on the optical path from the dichroic mirror 133 to the sample stage 135 for providing illumination.

[0054] The OCT measurement system provided in the above embodiment of the present application works as follows:

[0055] The laser beam emitted by the light source 111 passes through the optical fiber circulator 112 to achieve unidirectional transmission and isolation of the optical path, and then is divided into reference light and sample light through the coupler 113 .

[0056] The reference light is collimated by the first collimator 121 and then enters the reflector 123 . After being reflected by the reflector 123 , the reference light passes through the first collimator 121 , the coupler 113 and the fiber circulator 112 in sequence and is then acquired by the spectrometer 140 .

[0057] The sample light is converted into parallel light by the second collimator 131 and then enters the scanning galvanometer 132. After being scanned by the scanning galvanometer 132, the sample light enters the dichroic mirror 133 and then is focused on the sample located on the sample stage 135 by the scanning lens 134 and excites the sample to generate backscattered light. The backscattered light is acquired by the spectrometer 140 after passing through the scanning lens 134, the dichroic mirror 133, the scanning galvanometer 132, the second collimator 131 and the fiber circulator 112 in sequence.

[0058] It can be understood that the sample light is converted into parallel light by the second collimator 131 and then enters the scanning galvanometer 132. By accurately controlling the scanning path of the scanning galvanometer 132, the direction of the light path can be flexibly adjusted, so that the light spot can perform two-dimensional scanning on the sample surface. At the same time, a long-wave pass dichroic mirror 133 is superimposed between the scanning galvanometer 132 and the scanning lens 134, so that the light path of the preview camera 150 and the OCT light path are coaxial, which simplifies the system structure, avoids the field of view of the preview camera 150 being limited by the movement of the scanning galvanometer 132, improves the flexibility and efficiency of the measurement, and provides a precise basis for sample positioning and posture adjustment for subsequent OCT scanning.

[0059] The spectrometer 140 performs OCT imaging based on the acquired light signal and the image is acquired by the computer 160. The computer 160 drives the sample stage 135 to perform z-axis lifting and lowering movement relative to the scanning lens 134 and automatically triggers the preview camera 150 to capture the current image of the sample stage 135 after each displacement, and records the movement distance of the sample stage 135 in real time. The computer 160 is also used to analyze the corresponding received image to determine the clearest focusing position of the sample, which is the optimal focusing state, and control the sample stage 135 to move to this position.

[0060] It should be noted that the real-time detection function of the preview camera 150 provides the system with instant sample position information. Before the measurement begins, the system can quickly identify and confirm whether the sample has been correctly placed in the OCT imaging field of view, avoiding repeated adjustments and measurement delays caused by improper sample positioning. At the same time, the preview camera 150 can also accurately capture the contour and position of the sample, providing accurate data support for subsequent scanning control.

[0061] It can be understood that the computer 160 uses the image clarity evaluation index to evaluate the clarity of each image to determine the clearest focusing position of the sample. When the position is found, the sample stage 135 is controlled to move to this point to ensure that the sample plane is accurately focused. During the scanning process, the spectrometer 140 will collect spectral information at different scanning points, and then convert this spectral information into clear OCT images through the OCT image reconstruction algorithm. From these OCT images, the sample 3D point cloud data can be further extracted for subsequent analysis.

[0062] In this embodiment, the computer 160 is also used to start the preview camera 150 to capture the picture again after the sample is in the optimal focus state, and use image processing technology to detect the position of the sample in the preview camera 150 to obtain ROI; the computer 160 also uses a pre-calibrated mapping table between the preview camera 150 and the scanning galvanometer 132 to calculate the control amount of the scanning galvanometer 132 corresponding to the ROI pixel position in the preview image.

[0063] For further information, see Figure 3 , is a sample measurement flow chart provided in this embodiment, which specifically includes the following steps:

[0064] Step S110: The computer 160 controls the sample stage 135 to move and calculates the displacement of the sample stage 135 and the corresponding image quality score curve to obtain the valley value of the curve, and then controls the sample stage 135 to move there.

[0065] It can be understood that the above-mentioned embodiment of the present application automatically determines whether the sample plane is at the focus position and moves it to the best focus position through the image quality evaluation score and the displacement curve, thereby improving the measurement accuracy.

[0066] Step S120: the computer 160 determines whether there is a sample within the calibrated field of view of the preview camera 150, and if so, proceeds to the next step; if not, moves the sample stage 135 to the calibrated field of view, and then proceeds to the next step;

[0067] Step S130: The user selects a ROI in the field of view or obtains the maximum circumscribed rectangle or circumscribed circle of the sample as the ROI;

[0068] Step S140: the computer 160 calculates the control amount of the scanning galvanometer 132 corresponding to the pixel position of the ROI according to the calibration mapping table between the preview camera 150 and the scanning galvanometer 132, and generates a scanning waveform corresponding to the ROI pixel area according to the mapping table to obtain a ROI image.

[0069] This embodiment utilizes the coaxiality of the preview camera 150 and the OCT optical path to calibrate the control amount of the scanning galvanometer 132 and the pixel mapping table of the preview camera 150. The user can select the area to be scanned or the system target recognition detection ROI area in the preview camera to control the OCT galvanometer to quickly scan the ROI.

[0070] Furthermore, a mapping table of the control amount of the scanning galvanometer 132 and the pixels of the preview camera 150 is obtained as follows: the calibration plate is placed in a focusing position, and the sample stage 135 is fine-tuned to make the calibration plate horizontal, and the calibration plate is scanned to obtain an OCT image of the calibration plate. After the scanning is completed, a picture of the current calibration plate of the preview camera 150 is captured, and point features are extracted and matched between the OCT image of the calibration plate and the picture of the current calibration plate of the preview camera 150, and the relationship between the pixels of the preview camera 150 and the control amount of the scanning galvanometer 132 is calculated to obtain the calibration mapping table.

[0071] In this embodiment, the calibration plate includes a checkerboard calibration plate or a circular calibration plate.

[0072] It can be understood that the present embodiment adopts an intelligent scanning control strategy. Through the pre-established control amount of the scanning galvanometer 132 and the preview camera 150 pixel mapping table, the system can quickly calculate the scanning control amount for a specific sample or ROI area. This intelligent scanning method not only reduces unnecessary scanning areas, but also ensures that the OCT beam can be accurately focused on the target area, thereby improving the resolution and accuracy of the measurement; in addition, the intelligent scanning control strategy also allows the user to flexibly adjust the scanning range and resolution as needed to adapt to different samples and measurement requirements. This flexibility makes the OCT measurement system more adaptable to a variety of application scenarios and provides users with a more convenient and efficient measurement experience.

[0073] The OCT measurement system provided in the above-mentioned embodiment of the present application realizes flexible adjustment of the direction of the optical path by precisely controlling the scanning path of the scanning mirror, so that the light spot can perform two-dimensional scanning on the sample surface. Since a long-wave pass dichroic mirror 133 is superimposed between the scanning galvanometer 132 and the scanning lens 134, the optical path of the preview camera 150 and the OCT optical path are coaxial, which simplifies the system structure, avoids the field of view of the preview camera 150 being limited by the movement of the scanning galvanometer 132, and improves the measurement flexibility and efficiency.

[0074] Example 2

[0075] See also Figure 4 , which is a flow chart of the steps of the OCT measurement method of the OCT measurement system provided in this embodiment 2, includes the following steps:

[0076] Step S210: The laser beam emitted by the light source 111 passes through the optical fiber circulator 112 to achieve unidirectional transmission and isolation of the optical path, and then passes through the coupler 113 to be divided into reference light and sample light;

[0077] Step S220: the reference light is collimated by the first collimator 121 and then incident on the reflector 123. After being reflected by the reflector 123, the reference light passes through the first collimator 121, the coupler 113 and the fiber circulator (112) in sequence and is then acquired by the spectrometer 140.

[0078] Step S230: the sample light is converted into parallel light by the second collimator 131 and then enters the scanning galvanometer 132. After being scanned by the scanning galvanometer 132, the sample light enters the dichroic mirror 133 and then is focused on the sample located on the sample stage 135 by the scanning lens 134 and excites the sample to generate backscattered light. The backscattered light is sequentially passed through the scanning lens 134, the dichroic mirror 133, the scanning galvanometer 132, the second collimator 131 and the fiber circulator 112 and then acquired by the spectrometer 140.

[0079] Step S240: The spectrometer 140 performs OCT imaging based on the acquired light signal and the image is acquired by the computer 160. The computer (160) drives the sample stage 135 to perform z-axis lifting and lowering movement relative to the scanning lens 134 and automatically triggers the preview camera 150 to capture the current image of the sample stage 135 after each displacement, and records the movement distance of the sample stage 135 in real time. The computer 160 is also used to analyze the received corresponding image to determine the clearest focusing position of the sample, which is the optimal focusing state, and control the sample stage 135 to move to this position.

[0080] The detailed implementation of the steps provided in the above embodiments of the present application can be found in Embodiment 1 and will not be repeated here.

[0081] The OCT measurement system provided in the above-mentioned embodiment of the present application realizes flexible adjustment of the direction of the optical path by precisely controlling the scanning path of the scanning mirror, so that the light spot can perform two-dimensional scanning on the sample surface. Since a long-wave pass dichroic mirror 133 is superimposed between the scanning galvanometer 132 and the scanning lens 134, the optical path of the preview camera 150 and the OCT optical path are coaxial, which simplifies the system structure, avoids the field of view of the preview camera 150 being limited by the movement of the scanning galvanometer 132, and improves the measurement flexibility and efficiency.

[0082] The above are only preferred embodiments of the present application, and only specifically describe the technical principles of the present application. These descriptions are only for explaining the principles of the present application and cannot be interpreted as limiting the scope of protection of the present application in any way. Based on the explanation here, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application, and other specific implementation methods of the present application that can be associated with the technicians in this field without creative work, should be included in the scope of protection of the present application.

Claims

1. An OCT measurement system, characterized in that: include: A light source unit (110), a reference arm optical path unit (120), a sample arm optical path unit (130), a spectrometer (140), a preview camera (150) and a computer (160), wherein: The light source unit (110) comprises a light source (111), an optical fiber circulator (112) and a coupler (113); The reference arm optical path unit (120) comprises a first collimator (121) and a reflector (123); The sample arm optical path unit (130) comprises a second collimator (131), a scanning galvanometer (132), a dichroic mirror (133), a scanning lens (134) and a sample stage (135); The laser beam emitted by the light source (111) passes through the optical fiber circulator (112) to achieve unidirectional transmission and isolation of the optical path, and then passes through the coupler (113) to be divided into reference light and sample light; The reference light is collimated by the first collimator (121) and then incident on the reflector (123). After being reflected by the reflector (123), the reference light sequentially passes through the first collimator (121), the coupler (113) and the optical fiber circulator (112) and is then acquired by the spectrometer (140); The sample light is converted into parallel light by the second collimator (131) and then enters the scanning galvanometer (132). After being scanned by the scanning galvanometer (132), the sample light enters the dichroic mirror (133) and then is focused on the sample located on the sample stage (135) by the scanning lens (134), and excites the sample to generate backscattered light. The backscattered light is sequentially passed through the scanning lens (134), the dichroic mirror (133), the scanning galvanometer (132), the second collimator (131) and the optical fiber circulator (112) and then is acquired by the spectrometer (140); The spectrometer (140) performs OCT imaging based on the acquired light signal and the image is acquired by the computer (160). The computer (160) drives the sample stage (135) to perform a z-direction lifting and lowering movement relative to the scanning lens (134) and automatically triggers the preview camera (150) to capture a current image of the sample stage (135) after each displacement, and records the movement distance of the sample stage (135) in real time. The computer (160) is also used to analyze the received corresponding image to determine the clearest focusing position of the sample, i.e., the best focusing state, and control the sample stage (135) to move to this position.

2. The OCT measurement system according to claim 1, characterized in that: The computer (160) is further used to start the preview camera (150) again to collect images after the sample is in the optimal focus state, and to detect the position of the sample on the preview camera (150) using image processing technology to obtain ROI; The computer (160) calculates the control amount of the scanning galvanometer (132) corresponding to the pixel position of the ROI according to a mapping table between the preview camera (150) and the scanning galvanometer (132).

3. The OCT measurement system according to claim 2, characterized in that: The computer (160) controls the movement of the sample stage (135) and calculates the displacement of the sample stage (135) and the corresponding image quality score curve to obtain the valley value of the curve, and then controls the sample stage (135) to move there; The computer (160) determines whether there is a sample within the calibrated field of view of the preview camera (150), and if so, proceeds to the next step; if not, moves the sample stage (135) to the calibrated field of view, and then proceeds to the next step; The user selects the ROI in the field of view or uses the maximum circumscribed rectangle or circumscribed circle of the sample as the ROI; The computer (160) calculates the control amount of the scanning galvanometer (132) corresponding to the pixel position of the ROI according to the calibration mapping table between the preview camera (150) and the scanning galvanometer (132), and generates a scanning waveform corresponding to the ROI pixel area according to the mapping table to obtain an ROI image.

4. The OCT measurement system according to claim 3, characterized in that: A calibration plate is provided at the focus position, the calibration plate is horizontally adjusted by fine-tuning the sample stage (135), the calibration plate is scanned to obtain an OCT image of the calibration plate, and after scanning, a picture of the calibration plate currently held by the preview camera (150) is captured, and point feature extraction and matching are performed on the OCT image of the calibration plate and the picture of the calibration plate currently held by the preview camera (150), and the relationship between the pixels of the preview camera (150) and the control amount of the scanning galvanometer (132) is calculated to obtain the calibration mapping table.

5. The OCT measurement system according to claim 4, characterized in that: The calibration plate includes a checkerboard calibration plate or a circular calibration plate.

6. The OCT measurement system according to claim 1, characterized in that: The spectrometer (140) converts the acquired light signal into the OCT image through an OCT image reconstruction algorithm according to the acquired light signal, and the OCT image can extract sample 3D point cloud data.

7. The OCT measurement system according to claim 1, characterized in that: The dispersion compensator (122) is also provided on the optical path from the first collimator (121) to the reflector (123) to compensate for the dispersion effect generated when the laser is transmitted in the optical fiber.

8. The OCT measurement system according to claim 1, characterized in that: An illumination LED (136) is also provided on the optical path from the dichroic mirror (133) to the sample stage (135).

9. The OCT measurement system according to claim 1, characterized in that: The computer (160) is also connected to a data control acquisition card (161), and the data control acquisition card (161) is electrically connected to the preview camera (150), the sample stage (135), the scanning galvanometer (132) and the spectrometer (140); the computer (160) is also electrically connected to the light source (111), and the light source (111) is a superluminescent diode.

10. An OCT measurement method of the OCT measurement system according to claim 1, characterized in that: The steps include: The laser beam emitted by the light source (111) passes through the optical fiber circulator (112) to achieve unidirectional transmission and isolation of the optical path, and then passes through the coupler (113) to be divided into reference light and sample light; The reference light is collimated by the first collimator (121) and then incident on the reflector (123). After being reflected by the reflector (123), the reference light sequentially passes through the first collimator (121), the coupler (113) and the optical fiber circulator (112) and is then acquired by the spectrometer (140); The sample light is converted into parallel light by the second collimator (131) and then enters the scanning galvanometer (132). After being scanned by the scanning galvanometer (132), the sample light enters the dichroic mirror (133) and then is focused on the sample located on the sample stage (135) by the scanning lens (134), and excites the sample to generate backscattered light. The backscattered light is sequentially passed through the scanning lens (134), the dichroic mirror (133), the scanning galvanometer (132), the second collimator (131) and the optical fiber circulator (112) and then is acquired by the spectrometer (140); The spectrometer (140) performs OCT imaging based on the acquired light signal and the image is acquired by the computer (160). The computer (160) drives the sample stage (135) to perform a z-direction lifting and lowering movement relative to the scanning lens (134) and automatically triggers the preview camera (150) to capture a current image of the sample stage (135) after each displacement, and records the movement distance of the sample stage (135) in real time. The computer (160) is also used to analyze the received corresponding image to determine the clearest focusing position of the sample, i.e., the best focusing state, and control the sample stage (135) to move to this position.

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