An OCT measurement system and method

Abstract

The OCT measurement system and method provided by the application comprises a light source unit, a reference arm optical path unit, a sample arm optical path unit, a spectrometer, a preview camera and a computer, the light source unit comprises a light source, a fiber optic circulator and a coupler; the reference arm optical path unit comprises a first collimator and a mirror; the sample arm optical path unit comprises a second collimator scanning galvanometer, a dichroic mirror, a scanning lens and a sample stage, the scanning path of the scanning galvanometer is accurately controlled, the direction of the optical path is flexibly adjusted, the light spot can be two-dimensionally scanned on the sample surface, a long-wave-pass dichroic mirror is superimposed between the scanning galvanometer and the scanning lens, the optical path of the preview camera is coaxial with the OCT optical path, the system structure is simplified, the field of view of the preview camera is not limited by the movement of the scanning galvanometer, and the flexibility and the measurement efficiency are improved.

Description

TECHNICAL FIELD

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

[0002] Optical coherence tomography (OCT) is an advanced imaging technology based on the principle of weak coherent light interference. It can generate two-dimensional or three-dimensional structure images of biological tissues by detecting the backscattering or scattering signals of incident weak coherent light at different depths of the biological tissues and through scanning 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 material science. With continuous innovation and continuous expansion of application fields, OCT technology will play an even more important and extensive role in the future.

[0004] Although OCT is an advanced imaging technology that has shown excellent performance in many fields, it still faces some challenges and limitations in actual application. One of the significant problems is that the precise placement of the focal plane is crucial to the measurement results. If it is not placed accurately, it may introduce measurement errors and reduce the reliability of the data. In addition, sample positioning is also a big challenge. If the sample cannot be correctly placed in the scanning field of view, or the process of judging the sample position is too time-consuming, it will directly affect the efficiency and experience of OCT. These problems often require the precise operation and rich experience of professional operators to solve, thereby increasing the requirement for the skill level of the operators. SUMMARY

[0005] Therefore, it is necessary to provide an OCT measurement system and a preparation method thereof capable of improving the measurement efficiency and flexibility to solve the technical defects of inaccurate focal plane positioning, time-consuming sample positioning, and low efficiency of large-scale scanning in the current OCT measurement system.

[0006] To solve the above problems, the technical scheme adopted by the present application is as follows:

[0007] One of the objects 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), a fiber optic circulator (112), and a coupler (113);

[0009] The reference arm optical path unit (120) comprises a first collimator (121) and a mirror (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) is transmitted in one direction and isolated by the optical fiber circulator (112), and then divided into reference light and sample light by the coupler (113);

[0012] The reference light is collimated by the first collimator (121), then reflected by the mirror (123), and then sequentially passes through the first collimator (121), the coupler (113), and the optical fiber circulator (112) to be acquired by the spectrometer (140);

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

[0014] The spectrometer (140) performs OCT image imaging according to the acquired light signal and is acquired by the computer (160). The computer (160) drives the sample stage (135) to move up and down in the z direction relative to the scanning lens (134) and automatically triggers the preview camera (150) to take a picture of the current 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 images received to determine the clearest focusing position of the sample as the best focusing state, and controls the sample stage (135) to move to the position.

[0015] In some embodiments, the computer (160) is also used to start the preview camera (150) to collect pictures again after the sample is in the best focusing state, and detect the position of the sample in the preview camera (150) using image processing technology to obtain the ROI;

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

[0017] In some embodiments, 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 to the position.

[0018] The computer (160) determines whether there is a sample in the field of view range of the preview camera (150) calibration, if yes, the next step is performed; if not, the sample stage (135) is moved to the field of view range of the calibration, and then the next step is performed.

[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 the scanning waveform corresponding to the ROI pixel area according to the mapping table to obtain the ROI image.

[0021] In some embodiments, the OCT focus position is provided with a calibration board, and the sample stage (135) is finely adjusted to make the calibration board horizontal, the calibration board is scanned to obtain a calibration board OCT image, and after the scanning is completed, the current picture of the calibration board of the preview camera (150) is collected, the relationship between the preview camera (150) pixel and the control amount of the scanning galvanometer (132) is calculated by performing point feature extraction and matching on the calibration board OCT image and the current picture of the calibration board of the preview camera (150), so as to obtain the calibration mapping table.

[0022] In some embodiments, the calibration board includes a chessboard calibration board or a circular ring calibration board.

[0023] In some embodiments, the spectrometer (140) converts the optical signal into the OCT image through an OCT image reconstruction algorithm according to the obtained optical signal, and the OCT image can extract sample 3D point cloud data.

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

[0025] In some embodiments, the illumination LED (136) is further arranged on the light path of the dichroic mirror (133) to the sample stage (135).

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

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

[0028] The laser beam emitted by the light source (111) is transmitted in one direction and isolated by the optical fiber circulator (112), and then divided into reference light and sample light by the coupler (113);

[0029] The reference light is collimated by the first collimator (121), then reflected by the mirror (123), and then sequentially passes through the first collimator (121), the coupler (113) and the optical fiber circulator (112) to be acquired by the spectrometer (140);

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

[0031] The spectrometer (140) images the OCT image according to the acquired optical signal and is acquired by the computer (160), the computer (160) drives the sample stage (135) to move up and down in the z direction relative to the scanning lens (134) and automatically triggers the preview camera (150) to take a picture of the current sample stage (135) after each displacement, and records the movement distance of the sample stage (135) in real time, and the computer (160) is also used for analyzing the corresponding images received to determine the clearest focusing position of the sample as the best focusing state, and controls the sample stage (135) to move to the position.

[0032] The present application adopts the above technical solutions, which has the following advantages:

[0033] The OCT measurement system and measurement method provided by the application, the laser beam emitted by the light source (111) is transmitted in one direction and isolated by the optical fiber circulator (112) to achieve the optical path, and then is divided into reference light and sample light by the coupler (113), the reference light is collimated by the first collimator (121), is incident on the mirror (123), is reflected by the mirror (123), and then is sequentially passed through the first collimator (121), the coupler (113) and the optical fiber circulator (112) and is acquired by the spectrometer (140), the sample light is converted into parallel light by the second collimator (131) and enters the scanning galvanometer (132), is scanned by the scanning galvanometer (132), enters the dichroic mirror (133), is focused on the sample 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 is acquired by the spectrometer (140), the spectrometer (140) performs OCT image imaging according to the acquired light signal and is acquired by the computer (160), the scanning path of the scanning mirror is accurately controlled, the direction of the optical path is flexibly adjusted, the light spot can be two-dimensionally scanned on the sample surface, a long-wave-pass dichroic mirror (133) is added 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, the system structure is simplified, the field of view of the preview camera (150) is not limited by the movement of the scanning galvanometer (132), and the flexibility and measurement efficiency of measurement are improved. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments of the application or the prior art description. Obviously, the drawings described below are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0035] Figure 1 The structure schematic diagram of the OCT measurement system provided by the embodiment 1 of the application.

[0036] Figure 2 The principle schematic diagram of the OCT measurement system provided by the embodiment 1 of the application.

[0037] Figure 3 The sample measurement flowchart provided by the embodiment 1 of the application.

[0038] Figure 4is a step flow chart of the OCT measurement method provided by Embodiment 2 of the present application. DETAILED DESCRIPTION

[0039] Embodiments of the present application are described in detail below with reference to examples thereof illustrated in the attached drawings, in which like or similar designations denote like or similar elements or components throughout the drawings. The embodiments described below are examples in which the present application is applied, and are intended to explain the present application, and cannot be understood as limiting the present application.

[0040] In the description of the present application, it needs to be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "horizontal", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the purpose of facilitating the description of the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0041] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features referred to. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise explicitly specified.

[0042] In order to make the purpose, technical solutions and advantages of the present application more clear and explicit, the present application is further described in detail below in combination with the drawings and embodiments.

[0043] Embodiment 1

[0044] Please refer to Figure 1 and Figure 2 is a structural schematic diagram of the OCT measurement system provided by the present application, which includes 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 solutions realized thereby are described in detail below.

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

[0046] In the present embodiment, the light source 111 uses an SLD (superluminescent diode) as a light source. The laser beam emitted by the light source 111 passes through the fiber optic circulator 112 to realize unidirectional transmission and isolation of the optical path. 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 mirror 123.

[0048] In the embodiment, the dispersion compensator 122 is arranged on the light path of the first collimator 121 to the mirror 123, which is used to compensate the dispersion effect of the laser in the optical fiber, so as to ensure the coherence between the reference light and the sample light, thereby improving the definition and accuracy of the interference signal.

[0049] The sample arm light 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.

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

[0051] It can be understood that the computer 160 can adjust the wavelength and frequency of the light source 111. The computer 160 can accurately control the scanning path of the scanning galvanometer 132 to realize the flexible adjustment of the light path direction, so that the light spot can be two-dimensionally scanned on the sample surface. The computer 160 can drive the sample stage 135 to perform accurate z-direction lifting motion relative to the scanning lens 134, and after each displacement, automatically trigger the preview camera 150 to shoot the picture of the current sample stage, and record the motion distance of the sample stage 135 in real time. The computer 160 can obtain the imaging information of the spectrometer 140.

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

[0053] In the embodiment, an illumination LED 136 is arranged on the light path from the dichroic mirror 133 to the sample stage 135, which is used to provide illumination.

[0054] The OCT measurement system provided by the above embodiment has the following working mode:

[0055] The laser beam emitted by the light source 111 is transmitted in one direction and isolated by the optical fiber circulator 112, and then divided into reference light and sample light by the coupler 113.

[0056] The reference light is collimated by the first collimator 121, then is incident on the mirror 123 and is reflected by the mirror 123, and then is sequentially acquired by the spectrometer 140 through the first collimator 121, the coupler 113 and the optical fiber circulator 112.

[0057] The sample light is converted into parallel light by the second collimator 131 and enters the scanning galvanometer 132, is scanned by the scanning galvanometer 132, enters the dichroic mirror 133, and is focused on the sample on the sample stage 135 by the scanning lens 134, and excites the sample to generate backscattered light. The backscattered light is sequentially acquired by the optical spectrum analyzer 140 through the scanning lens 134, the dichroic mirror 133, the scanning galvanometer 132, the second collimator 131, and the fiber ring 112.

[0058] It can be understood that the sample light is converted into parallel light by the second collimator 131 and enters the scanning galvanometer 132. By precisely controlling the scanning path of the scanning galvanometer 132, the direction of the light path is flexibly adjusted, so that the light spot can be two-dimensionally scanned on the sample surface. Meanwhile, 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 is coaxial with the OCT light path, the system structure is simplified, the field of view of the preview camera 150 is not limited by the movement of the scanning galvanometer 132, the flexibility and efficiency of measurement are improved, and accurate sample positioning and attitude adjustment are provided for subsequent OCT scanning.

[0059] The OCT image is imaged by the optical spectrum analyzer 140 according to the acquired light signal and is acquired by the computer 160. The computer 160 drives the sample stage 135 to move up and down in the z direction relative to the scanning lens 134 and automatically triggers the preview camera 150 to shoot the current picture 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 for analyzing the corresponding images received to determine the best focus state of the sample, and controls the sample stage 135 to move to the position.

[0060] It should be noted that the real-time detection function of the preview camera 150 provides instant sample position information for the system. Before measurement starts, the system can quickly identify and confirm whether the sample has been correctly placed in the OCT imaging field of view, avoiding repeated adjustment and measurement delay due to improper sample position. Meanwhile, the preview camera 150 can accurately capture the profile and position of the sample, providing accurate data support for subsequent scanning control.

[0061] It can be understood that the computer 160 uses an image sharpness evaluation index to evaluate the sharpness of each image to determine the sharpest focus position of the sample. When the position is found, the sample stage 135 is controlled to move to the point to ensure accurate focusing of the sample plane. In the scanning process, the optical spectrum analyzer 140 collects spectral information of different scanning points, and then converts the spectral information into clear OCT images through an OCT image reconstruction algorithm. From these OCT images, 3D point cloud data of the sample can be further extracted for subsequent analysis.

[0062] In the embodiment, the computer 160 is further configured to, after the sample is in the best focus state, start the preview camera 150 to capture a picture again, and detect the position of the sample in the preview camera 150 by using image processing technology to obtain the ROI; the computer 160 further calculates the control amount of the scanning galvanometer 132 corresponding to the pixel position of the ROI in the preview image according to the mapping table between the preview camera 150 and the scanning galvanometer 132 which is calibrated in advance.

[0063] Further, referring to Figure 3 The sample measurement flowchart provided in the embodiment 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 to the position.

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

[0066] Step S120: The computer 160 judges whether there is a sample in the field of view range calibrated by the preview camera 150, if yes, the next step is performed; if not, the sample stage 135 is moved to the field of view range calibrated, and then the next step is performed.

[0067] Step S130: The user selects the ROI in the field of view by framing 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 mapping table between the preview camera 150 and the scanning galvanometer 132, and generates the scanning waveform corresponding to the ROI pixel region according to the mapping table to obtain the ROI image.

[0069] The embodiment uses the coaxiality of the preview camera 150 and the OCT optical path to calibrate the pixel mapping table of the scanning galvanometer 132 and the preview camera 150, the user can select the scanning region or the system target recognition detects the ROI region in the preview camera, and controls the OCT galvanometer to quickly scan the ROI.

[0070] Further, the mapping table of the control amount of the scanning galvanometer 132 and the pixels of the preview camera 150 is obtained by the following steps: placing the calibration board at the focus position, fine-tuning the sample table 135 to make the calibration board horizontal, scanning the calibration board to obtain a calibration board OCT image, capturing a picture of the calibration board of the preview camera 150 after scanning, and calculating the relationship between the pixels of the preview camera 150 and the control amount of the scanning galvanometer 132 by point feature extraction and matching of the calibration board OCT image and the picture of the calibration board of the preview camera 150, to obtain the calibration mapping table.

[0071] In the embodiment, the calibration board includes a chessboard calibration board or a circular ring calibration board.

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

[0073] The OCT measurement system provided by the above-mentioned embodiments of the present application can accurately control the scanning path of the scanning mirror, flexibly adjust the direction of the light path, and enable the light spot to 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 light path of the preview camera 150 is coaxial with the OCT light path, which simplifies the system structure, avoids the limitation of the field of view of the preview camera 150 by the movement of the scanning galvanometer 132, and improves the flexibility and efficiency of the measurement.

[0074] Embodiment 2

[0075] Please refer to Figure 4 The step flow chart of the OCT measurement method of the OCT measurement system provided by the above-mentioned embodiment 2 includes the following steps:

[0076] Step S210: The laser beam emitted by the light source 111 is transmitted in one direction and isolated by the optical fiber circulator 112, and then divided into reference light and sample light by the coupler 113;

[0077] Step S220: the reference light is collimated by the first collimator 121, then is reflected by the mirror 123, and then is sequentially passed through the first collimator 121, the coupler 113 and the fiber circulator (112) to be acquired by the spectrometer 140;

[0078] Step S230: the sample light is converted into parallel light by the second collimator 131, then enters the scanning galvanometer 132, is scanned by the scanning galvanometer 132, enters the dichroic mirror 133, is focused on the sample on the sample stage 135 by the scanning lens 134, and excites the sample to generate backscattering light, which 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 to be acquired by the spectrometer 140;

[0079] Step S240: the spectrometer 140 performs OCT image imaging according to the acquired light signal, and the computer 160 acquires the OCT image, the computer (160) drives the sample stage 135 to move up and down in the z direction relative to the scanning lens 134, and automatically triggers the preview camera 150 to take a picture of the current 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 for analyzing the corresponding images received to determine the best focus state of the sample, and controls the sample stage 135 to move to the position.

[0080] The detailed implementation of the steps provided in the above embodiments of the application can be referred to the embodiment 1, which will not be described here.

[0081] The OCT measurement system provided in the above embodiments of the application can flexibly adjust the direction of the light path by precisely controlling the scanning path of the scanning mirror, so that the light spot can be two-dimensionally scanned on the sample surface. Since a long-wave-pass dichroic mirror 133 is added between the scanning galvanometer 132 and the scanning lens 134, the light path of the preview camera 150 is coaxial with the OCT light path, which simplifies the system structure, avoids the limitation of the field of view of the preview camera 150 by the movement of the scanning galvanometer 132, and improves the flexibility and efficiency of the measurement.

[0082] The above is only a preferred embodiment of the application, and only the technical principles of the application are specifically described, which are only for explaining the principles of the application and cannot be interpreted as limiting the protection scope of the application in any way. Based on the explanation herein, any modification, equivalent replacement and improvement made within the spirit and principle of the application, and other specific embodiments of the application that can be conceived by those skilled in the art without creative labor, should be included in the protection scope of the 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) includes a first collimator (121) and a reflector (123); 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); 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 passes through the first collimator (121), the coupler (113), and the 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). 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 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 motion 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 focus position of the sample, that is, the best focus state, and control the sample stage (135) to move to this position; wherein: 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 largest 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 a 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; A calibration plate is provided at the focus position, and 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. After the scanning is completed, a picture of the calibration plate currently held by the preview camera (150) is captured. 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.

2. The OCT measurement system according to claim 1, wherein: The computer (160) is further configured to restart the preview camera (150) to capture 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 a 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, wherein: The calibration plate includes a checkerboard calibration plate or a circular calibration plate.

4. The OCT measurement system according to claim 1, wherein: 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.

5. The OCT measurement system according to claim 1, wherein: A 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.

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

7. The OCT measurement system according to claim 1, wherein: The computer (160) is further 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 further electrically connected to the light source (111), and the light source (111) is a superluminescent diode.

8. 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 passes through the first collimator (121), the coupler (113), and the 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). 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 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-axis lifting 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, that is, the optimal focusing state, and control the sample stage (135) to move to this position.

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