Optical film surface defect detection system

Abstract

The invention provides an optical thin film surface defect detection system which is particularly suitable for optical thin film, wafer and sensor detection. The system integrates an illumination module, a confocal positioning module, a differential microscopic interference module, a phase shift module, an imaging module and a data processing module. A double-light-path imaging mode is adopted, wherein a differential interference microscopic light path recorded by a CCD and a microscopic dark field imaging light path are adopted. The differential interference microscopic light path obtains the microstructure and phase distribution information of the surface of the thin film with high sensitivity by using interference and phase shift technologies; the microscopic dark field imaging light path highlights film surface defects, particles and micro-nano structure characteristics by enhancing surface scattering signals. The device has the characteristics of simple structure, large single measurement range, high resolution, excellent precision and the like, effectively overcomes the defects of three-dimensional information loss, low efficiency, narrow application range, difficulty in positioning and the like in the traditional technology, and remarkably improves the detection efficiency and applicability.

Description

Technical Field

[0001] The present invention relates to the technical field of precision optical detection, and particularly relates to an optical thin film surface defect detection system. Background Art

[0002] Optical thin films refer to one or more layers of thin film materials with special optical properties plated or coated on optical elements or independent substrates. In the production and preparation of optical thin films, affected by various factors, various defects that affect the surface flatness and original optical properties of the thin film are likely to occur on its surface. In order to ensure the quality of optical thin films, it is often necessary to collect images of the prepared thin films and perform defect detection.

[0003] In the current industrial production process, the acquisition method of optical thin film images basically uses the traditional camera acquisition method, which flatly shoots the optical thin film and has the disadvantage of unstable accuracy, which will affect the subsequent thin film defect recognition effect. And it can only obtain the two-dimensional image information of the thin film, and it is difficult to realize the acquisition of the three-dimensional information on the surface of the thin film through a single detection. Although contact methods such as surface profilers and atomic force microscopes can realize the detection of the three-dimensional information on the surface of optical thin films, they are likely to cause secondary damage to their surfaces.

[0004] Chinese Patent with Document Number CN 113740034 B, although it also discloses the detection of thin films based on optical interference, it only uses the most basic optical system to perform interference principle imaging. It does not use a microscope objective lens for precise imaging, lacks a link to judge the focusing state of the detection sample, and cannot achieve high-precision image acquisition; and only performs subsequent detection based on the obtained two-dimensional image, relying too much on the training accuracy of the detection model; uses a basic improved convolutional neural network and lacks the real-time performance of detection. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an optical thin film surface defect detection system, which can simultaneously realize the acquisition of two-dimensional and three-dimensional information of the thin film, improve the reliability of the entire system, and reduce the labor intensity of the measurement personnel.

[0006] To achieve the purpose of the present invention, the technical solution provided by the present invention is as follows:

[0007] An optical thin film surface defect detection system, comprising: an illumination module for forming a collimated beam, and the collimated beam forms circularly polarized light after passing through a polarizer and a first quarter-wave plate;

[0008] A confocal positioning module that divides the circularly polarized light into two linearly polarized light beams through a first polarization beam splitter prism therein, one of the light beams reaches a photodetector PD therein through an imaging lens therein, and the other light beam enters a differential microscopic interference module;

[0009] The differential microscopic interference module is internally provided with a second polarization beam splitter prism for splitting another incoming light beam into upper and lower light beams. The upper light beam enters the phase shift module; the lower light beam is irradiated on the surface of the optical axis crystal through a relay lens. The optical axis crystal differentially shears the light beam into two linearly polarized light beams with perpendicular vibration directions. The two linearly polarized light beams are converged on the surface of the optical thin film through a microscopic objective lens to form a reflected light beam. The reflected light beam passes through the microscopic objective lens and the optical axis crystal again and then is synthesized into a reflected light beam and returns. At the second polarization beam splitter prism, it is split into two reflected light beams again. One reflected light beam enters the phase shift module; the other reflected light beam returns to the confocal positioning module.

[0010] The phase shift module is provided with a second quarter-wave plate and an analyzer for performing phase shift processing on the upper light beam and one reflected light beam. The processed light beam enters the imaging module.

[0011] The imaging module includes a Tube imaging lens and a CCD. The Tube imaging lens is used to receive one reflected light beam and the upper light beam after phase shift to form interference fringes; the CCD is used to collect the interference fringes.

[0012] The data processing module includes a PC. The PC is connected to a photodetector PD and a CCD, and is used to receive and process the signals from the photodetector PD and the CCD to obtain information on the surface of the optical thin film.

[0013] Furthermore, the illumination module includes a light source, a tunable attenuator, and a 4f beam shaping system located on the same horizontal axis. The light source is used to generate a light beam, and a collimated light beam is formed through the tunable attenuator and the 4f beam shaping system.

[0014] Furthermore, the first polarization beam splitter prism, the imaging lens, and the photodetector PD of the confocal positioning module are sequentially arranged in the detection light synthesis device from bottom to top and are located on the same horizontal axis.

[0015] Furthermore, the second polarization beam splitter prism, the relay lens, the optical axis crystal, and the microscopic objective lens of the differential microscopic interference module are arranged in order from top to bottom and are located on the same vertical axis.

[0016] Furthermore, the microscopic objective lens includes an annular aperture and a condenser. The annular aperture is used to reduce the two linearly polarized light beams into a circle and obliquely irradiate the sample surface through the periphery of the condenser.

[0017] The signal of the photodetector PD is: the signal of converting the light intensity signal of a beam of light into an electrical signal, and this signal is transmitted to the PC for digital processing and spectral calibration to judge the focusing state of the optical thin film; the signal of the CCD is: the signal of converting the optical interference image formed by the CCD collecting optical interference fringes into an electrical signal, and this signal is transmitted to the PC for subsequent processing.

[0018] Furthermore, the data processing module further includes measurement software, and the measurement software is used to detect the defects of the optical interference images collected by the CCD.

[0019] Furthermore, the measurement software is used to detect the defects of the optical interference images collected by the CCD. Specifically, the YOLOv10 network is used to detect the defects of the optical interference images.

[0020] Furthermore, the data processing module further includes a driver rotator, and the driver rotator is used to adjust the parameters of the measurement software to control the three-dimensional displacement platform, and the three-dimensional displacement platform is located below the microscope objective lens.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The present invention combines the reflective Köhler illumination method and innovatively integrates a dual-light-path imaging mode to form a complementary surface detection scheme. The differential interference microscopy light path utilizes interference and phase-shift technologies to highly sensitively obtain the microscopic morphology and phase distribution information of the thin film surface; the microscopic dark-field imaging light path effectively highlights the surface defects, particles, and micro-nano structure features of the thin film by enhancing the surface scattering signal. The two imaging light paths can work independently or jointly to realize multi-dimensional optical property analysis from the overall morphology of the thin film to local defects. In addition, a confocal module is equipped to improve the accuracy of image acquisition. Specifically, it is reflected in the following aspects:

[0023] 1) By means of polarized light and beam expander and collimator devices, the focusing characteristics of the light beam are improved, the quality of the detection light is enhanced, and high-quality optical input conditions are provided for subsequent interference analysis.

[0024] 2) Microscopic dark-field imaging helps to reveal the information of tiny defects and particles on the sample surface by enhancing the contrast of scattered light, providing more details for the surface quality of the thin film.

[0025] 3) Combining three-dimensional topography data with two-dimensional scattering data provides a more comprehensive thin film quality analysis to ensure a comprehensive evaluation of surface defects and optical properties; the two-dimensional image detection uses an improved YOLOv10 network to maximize the real-time performance and accuracy of detection.

[0026] 4) The light intensity signal of the light beam is converted into an electrical signal by the confocal positioning module for digital processing and spectral calibration. This can not only judge the focusing state of the sample, but also improve the depth resolution and data accuracy of the system, significantly enhancing the accuracy of image acquisition. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FIG. is a schematic structural diagram of an optical thin film surface imaging system based on differential interference imaging provided by the present invention.

[0028] Figure 2 FIG. is a flowchart for defect recognition of an optical thin film image in the present invention.

[0029] Figure 3 FIG. is a structural diagram of an improved YOLOv10 network used for two-dimensional image defect detection in the present invention.

[0030] Figure 4 FIG. is a schematic diagram of defects of an optical thin film as the detection object proposed by the present invention, where different colors represent different types of defects.

[0031] Figure 1 In the figure: 1 - illumination module, 2 - confocal positioning module, 3 - differential microscopic interference module, 4 - phase shift module, 5 - imaging module, 6 - data processing module, 7 - light source, 8 - tunable attenuator, 9 - 4f beam shaping system, 10 - polarizer, 11 - first quarter-wave plate, 12 - first polarization beam splitter prism, 13 - imaging lens, 14 - photodetector PD, 15 - second polarization beam splitter prism, 16 - relay lens, 17 - optical axis crystal, 18 - microscopic objective lens, 19 - three-dimensional displacement platform, 20 - second quarter-wave plate, 21 - analyzer, 22 - Tube imaging lens, 23 - CCD, 24 - PC, 25 - driver rotator, 26 - measurement software. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The system and detection method of the present invention will be described in detail below with reference to the accompanying drawings.

[0033] See Figure 1, an optical thin film surface defect detection system, mainly including an illumination module 1, a polarizer 10, a first quarter-wave plate 11, a confocal positioning module 2, a differential microscopic interference module 3, a phase shift module 4, an imaging module 5 and a data processing module 6; the illumination module 1 includes a light source 7, a tunable attenuator 8, and a 4f beam shaping system 9; the light emitted by the light source sequentially passes through the above components and then passes through the polarizer 10 and the first quarter-wave plate 11 in sequence; the axes of the light source 7, the tunable attenuator 8, the 4f beam shaping system 9, the polarizer 10 and the first quarter-wave plate 11 are located on the same straight line; the confocal positioning module 2 includes a first polarization beam splitter prism 12, an imaging lens 13, and a photodetector PD14; arranged in the detection light synthesis device in the order from top to bottom, and the axes of each component are located on the same straight line; the light beam enters the first polarization beam splitter prism 12 after passing through the first quarter-wave plate 11; the photodetector PD14 is connected to the PC24 of the data processing module 6 for information transmission connection; the differential interference module 3 is composed of a second polarization beam splitter prism 15, a relay lens 16, an optical axis crystal 17, a microscopic objective lens 18, and a three-dimensional displacement platform 19 arranged in the detection light receiving device in the order from bottom to top, and their axes are all on the same axis; the light enters the second quarter-wave plate 20 of the phase shift module 4 through the second polarization beam splitter prism 15; the phase shift module 4 is composed of a second quarter-wave plate 20 and an analyzer 21; the light sequentially passes through the second quarter-wave plate 20 and the analyzer 21 and then enters the Tube imaging lens 22 of the imaging module 5; the imaging module 5 includes a CCD 23 and a Tube imaging lens 22, and the CCD 23 transmits information to the PC24 of the data processing module 6; the data processing module 6 includes a PC24, a driver rotator 25, and a measurement software 26; the PC24 interacts with the driver rotator 25; the PC24 transmits information to the measurement software 26.

[0034] The detection method of the optical thin film surface defect detection system provided by the present invention includes the following steps:

[0035] Place the optical thin film to be detected on the three-dimensional motion platform 19, and through the driver rotator 25 acting on the measurement software 26 communicatively connected to the PC24, further control the three-dimensional motion platform 19 to ensure that the surface of the thin film is in the best focal plane of the optical system. Emit a white light beam through the light source 7, and after the incident light beam is adjusted in light intensity by the attenuator 8, it enters the beam expansion, collimation and filtering system to optimize the beam quality and form a collimated beam; the collimation and filtering system is a 4f beam shaping system 9 which is specifically a system composed of two convex lenses.

[0036] The collimated incident light beam passes through the polarizer 10 at an angle to form a linearly polarized light, and is converted into a circularly polarized light by the first quarter-wave plate 11 at an angle α = 45°, and the phase delay is expressed by the following formula:

[0037]

[0038] Wherein, Δn is the refractive index difference, d is the propagation distance of light in the wave plate, and λ is the wavelength of light;

[0039] The phase difference of the first 1 / 4 wave plate here is The light beam is converted into circularly polarized light. The circularly polarized light is equivalent to the superposition of two linearly polarized lights with equal intensity and perpendicular to each other. After the light beam is converted into circularly polarized light, the first polarization beam splitter prism 12 can separate the light beam more precisely, laying a foundation for subsequent interference imaging;

[0040] After the incident circularly polarized light passes through the first polarization beam splitter prism 12 with an angle of θ = 45°, it is divided into two linearly polarized lights with perpendicular polarization directions. One of the incident light beams passes through the imaging lens 13 and reaches the photodetector PD14 inside it; the other incident light beam enters the second polarization beam splitter prism 15;

[0041] The second polarization beam splitter prism 15 divides the linearly polarized light into upper and lower light beams. The upper incident light beam enters the phase shift module 4 and undergoes phase delay through the second 1 / 4 wave plate 20 with an angle of α = 45°, and is converted into circularly polarized light; the lower incident light beam is irradiated on the surface of the optical axis crystal through the relay lens 13. The optical axis crystal 17 differentially shears the linearly polarized light into two linearly polarized lights with perpendicular vibration directions, and the shearing direction forms a fixed angle with the surface of the optical thin film;

[0042] The sheared light beam converges on the surface of the optical thin film through the microscope objective 18. The microscope objective 18 includes an annular aperture and a condenser lens, and the annular aperture is located above the condenser lens. The light beam is reduced to a circle by the annular aperture, passes through the periphery of the condenser lens, and is obliquely irradiated on the sample to form microscopic dark field imaging. The reflective Köhler illumination method reduces stray light and improves the uniformity of illumination. The reflected light beam finally carries the microscopic morphology information of the thin film sample;

[0043] The reflected light beam passes through the microscope objective 18 and the optical axis crystal 17 again and then synthesizes and returns. It is divided into two reflected light beams by the second polarization beam splitter prism 15. One of the reflected light beams enters the confocal positioning module 2 for optical processing. This light beam is reflected by the first polarization beam splitter prism 12 and then passes through the imaging lens 13. The corresponding light intensity signal enters the photodetector PD14, is converted into an electrical signal and transmitted to the PC24 for digital processing and spectral calibration to judge the focusing state of the sample, thereby improving the depth resolution and data accuracy of the system;

[0044] The other reflected light beam enters the phase shift module 4 after passing through the second polarization beam splitter prism 15. After the light beam is reflected, the polarization direction will change. Therefore, this reflected light beam is converted into a new linearly polarized light after passing through the second 1 / 4 wave plate 20, and the phase also changes. Compared with the upper incident light beam, its phase lags by Therefore, the two light beams passing through the phase shift module 4 have a constant phase difference.

[0045] The analyzer 21 ensures that the vibration directions of the two light beams (the incident light beam on the upper path and the reflected light beam on the other path) are the same, satisfying the coherence condition. The two light beams are coherent with each other, generating an interference field, enabling the longitudinal thickness of the measured surface to be represented by the light intensity contrast. The intensity formula of the generated interference image is as follows:

[0046] I = I 0 cos 2 (Δφ)

[0047] In the formula, I is the light intensity of the interference pattern, I 0 is the light intensity of the light beam entering the analyzer (i.e., the light intensity of the incident light beam on the upper path and the reflected light beam on the other path), and Δφ is the phase difference between the two light beams.

[0048] The CCD 23 records the interference field generated by the two coherent light beams and displays the measurement results with a relief feeling of the thin film's microscopic morphology and characteristics in real time. The microscopic dark-field imaging optical path in the system further enhances the imaging contrast of surface defects, particles, and micro-nano structures. The finally generated two-dimensional scattering image obtains the scattering characteristics of the sample surface and records the shape, size, and distribution information of the defects.

[0049] The CCD can simultaneously collect two-dimensional interference images and two-dimensional non-interference ordinary images. For the collected interference images, they are converted into electrical signals, digitized by an image acquisition card, and then transmitted to the PC for subsequent processing. The interference images carry information such as phase difference, interference fringes, light intensity, and minute object information. By calculating the phase distribution of the interference images, the three-dimensional data information shown in the thin film images can be obtained.

[0050] Regarding the principle of interference imaging based on two coherent light beams with a phase difference, the phase extraction method is used to calculate the phase distribution of the interference fringes. Two interference images with a phase difference of are respectively obtained, and their interference light intensities are:

[0051] I 1 (x,y) = I 0 (x,y) + I m (x,y)cos[φ(x,y)]

[0052]

[0053] In the formula, I 1 (x,y), I 2 (x,y) are respectively the interference light intensities of the two images, and I 0(x, y) is the background light intensity, obtained by taking an interference-free image, I m (x, y) is the amplitude of the interference fringes, and φ(x, y) is the phase distribution to be determined;

[0054] Using trigonometric identities, eliminate the amplitude I m , and obtain the following formula for the phase. Through this formula, the phase distribution of the interference fringes can be calculated:

[0055]

[0056] During the actual measurement process, the phase value will be restricted between 0 ≤ φ ≤ 2π. If the phase undergoes a change that crosses 2π, it will "jump", resulting in inaccurate measurement results. To accurately reconstruct the three-dimensional height of the thin film surface, before solving the height information, phase unwrapping processing is performed to obtain a continuous phase map and correct the jumping phase information;

[0057] Using the global unwrapping model, by minimizing the phase gradient, optimize the phase structure of the overall image. It ensures the smoothness of the overall image by gradually correcting the phase of each pixel. The specific optimization function is:

[0058]

[0059] Among them, respectively represent the change rates of the phase field in the x direction and the y direction;

[0060] During the optimization process, by calculating the gradient of the objective function E(φ) with respect to the phase field, gradually minimize it to find the optimal solution, and continuously adjust the phase. Finally, obtain the optimized continuous phase map φ unwrapped ;

[0061] After obtaining the continuous phase map, the three-dimensional height information of the sample surface can be calculated through the formula. The relationship between the interference fringe phase and the surface height h(x, y) can be expressed as:

[0062]

[0063] In the formula, λ is the wavelength of light, n eff is the effective refractive index, and h(x, y) is the height of the sample surface relative to the reference surface;

[0064] Through the above formula, the height of the sample surface relative to the reference surface can be finally calculated, that is, the three-dimensional visualization of the thin film surface defects can be performed, and finally the three-dimensional height information of the sample surface can be obtained;

[0065] The two-dimensional non-interference ordinary image obtained by the CCD is simultaneously input into the measurement software (26) used for defect detection for subsequent processing. The specific defect recognition process is asFigure 2 As shown in the figure. An improved YOLOv10 network is used to detect film defects. Among them, the quality of the dataset determines the training effect of the defect detection model of the network;

[0066] First, the image enhancement method is used to expand the image dataset, and the methods of cropping, rotating and brightening are adopted to improve the quality of the dataset for subsequent model training;

[0067] For the complex and diverse film defects, the direct use of the original YOLOv10 network has poor effects. In view of the characteristics of the variety and complexity of the film defect types, the YOLOv10 network is improved. The structure diagram of the improved YOLOv10 network is as Figure 3 shown, and the red frame area is the improved structure;

[0068] The specific improvement is to replace the Conv layer of the backbone network with the RefConv convolution, introduce the CARAFE sampling method and the BiFPN pyramid network structure into the neck network, and add the STA global attention mechanism. The above improvements can enhance the feature extraction ability of the model for tiny defects and long-distance defects, and realize high-precision and real-time defect detection of film images;

[0069] The data processing module 6 integrates the three-dimensional topography data obtained by processing the two-dimensional interference image and the two-dimensional defect recognition result obtained by processing the two-dimensional non-interference ordinary image. First, spatial mapping is performed to align the three-dimensional and two-dimensional information to the same reference system for analysis. The specific process of the mapping is as follows:

[0070] First, key points (such as edge points, corner points) in the three-dimensional topography data and key information (such as the center point of the rectangular box, four corner points, etc.) in the defect area of the two-dimensional YOLO detection result image are extracted for feature point matching; then, the coordinate alignment between the three-dimensional data and the two-dimensional image is realized through affine transformation, and the transformation relationship between the matching points is found through the RANSAC random sample consensus algorithm, and an affine transformation matrix is calculated. The process includes changes such as translation, scaling and rotation. The formula is as follows:

[0071]

[0072] Among them, a, b, c, d are the parameters of the affine transformation, t x t y is the translation amount;

[0073] Finally, the coordinates of the two-dimensional YOLO detection result area are mapped to the coordinate system of the three-dimensional topography map through affine transformation; the defect information detected by YOLO is cross-validated with the calculation results of the three-dimensional topography data to integrate the height distribution and local defect conditions of the sample surface. The threshold for cross-validation is set according to the actual defect types and characteristics of the measured components, and the admissibility of the three-dimensional and two-dimensional information is judged respectively to determine whether the area of the component is a defect. Finally, a comprehensive detection result of the thin film is generated, realizing the efficient and accurate detection of surface defects of optical thin films and the same type of optical components by this system.

[0074] Figure 4 It is a schematic diagram of common defect types of optical thin films. Among them, there are both long-distance and large-size defects (such as crystal lines and cracks in the figure), and small-size defects (such as light dots and sunken dots in the figure). Overall, they have the characteristics of diverse types and sizes, different shapes, and being easily confused with the thin film background. Combining other defect types that appear in actual production, the present invention can efficiently and accurately identify and detect these complex and diverse optical thin film defects by performing three-dimensional and two-dimensional information processing on the collected images.

[0075] It should be noted that the connection method between the PC24, the drive rotator 25, and the measurement software 26 in the data processing module 6 is not fixed. The drive rotator 25 and the measurement software 26 can be the drive rotator 25 and the measurement software 26 installed in the PC24, or can be independently set, and the three-dimensional displacement platform 19 can also be directly controlled by operating the PC24.

[0076] It should be noted that the differential interference microscopy optical path of the present invention is the optical path formed by the upper incident light beam entering the Tube imaging lens 22 in the imaging module 5 and another reflected light beam. This differential interference microscopy optical path uses interference and phase shift technologies to highly sensitively obtain the microscopic topography and phase distribution information of the thin film surface.

[0077] The microscopic dark-field imaging optical path is the optical path where linearly polarized light is split downward by the second polarization beam splitter prism 15 and then passes through the relay lens 16, the optical axis crystal 17, and the microscopic objective lens 18 in sequence. This microscopic dark-field imaging optical path uses the annular aperture and condenser lens configured on the microscopic objective lens 18 to make the incident light irradiate the sample from the side at an inclined angle and not directly enter the condenser lens. Only the scattered light is changed in the propagation direction and enters the condenser lens for imaging, so that the imaging result has a pitch-black background and the sample details are clearly visible, highlighting the surface defects, particles, and micro-nano structure characteristics of the thin film.

[0078] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. An optical film surface defect detection system, characterized in that: include: An illumination module (1) is used to form a collimated light beam, wherein the collimated light beam passes through a polarizer (10) and a first quarter wave plate (11) to form circularly polarized light; A confocal positioning module (2) is configured to split the circularly polarized light into two polarized light paths through a first polarization beam splitter prism (12) therein, wherein one light path passes through an imaging lens (13) therein and reaches a photodetector PD (14) therein, and the other light path enters a differential microscopy interference module (3); The differential microscopic interference module (3) is provided with a second polarization beam splitter prism (15) for splitting the other incoming light beam into two upper and lower light beams, wherein the upper light beam enters the phase shift module (4); the lower light beam is irradiated onto the surface of the optical axis crystal (17) via a relay lens (16); the optical axis crystal (17) differentially shears the light beam into two linear polarized light beams with mutually perpendicular vibration directions; the two linear polarized light beams converge on the surface of the optical film through a microscope objective lens (18) to form a reflected light beam; the reflected light beam passes through the microscope objective lens (18) and the optical axis crystal (17) again to form a reflected light beam and returns; and is split into two reflected light beams again at the second polarization beam splitter prism (15); one reflected light beam enters the phase shift module (4); and the other reflected light beam returns to the confocal positioning module (2); The phase shift module (4) is provided with a second 1 / 4 wave plate (20) and an analyzer (21), and is used to perform phase shift processing on the upstream light beam and the reflected light beam, and the processed light beams enter the imaging module (5); An imaging module (5) comprises a tube imaging lens (22) and a CCD (23), wherein the tube imaging lens (22) is used to receive a phase-shifted reflected light beam and an upstream light beam to form interference fringes; and the CCD (23) is used to collect the interference fringes. The data processing module (6) comprises a PC (24), wherein the PC (24) is connected to the photodetector PD (14) and the CCD (23) and is used for receiving and processing signals from the photodetector PD (14) and the CCD (23) to obtain information on the surface of the optical film.

2. The optical film surface defect detection system according to claim 1, characterized in that: The lighting module (1) comprises a light source (7), a tunable attenuation plate (8) and a 4f beam shaping system (9) located on the same horizontal axis; the light source is used to generate a light beam, which is formed into a collimated light beam via the tunable attenuation plate (8) and the 4f beam shaping system (9).

3. The optical film surface defect detection system according to claim 1, characterized in that: The first polarization beam splitter prism (12), imaging lens (13) and photodetector PD (14) of the confocal positioning module (2) are arranged in sequence from bottom to top in the detection light synthesis device and are located on the same horizontal axis.

4. The optical film surface defect detection system according to claim 1, characterized in that: The second polarization beam splitting prism (15), relay lens (16), optical axis crystal (17) and microscope objective lens (18) of the differential microscopic interference module (3) are arranged in order from top to bottom and are located on the same vertical axis.

5. The optical film surface defect detection system according to claim 1, characterized in that: The microscope objective lens (18) comprises an annular aperture and a condenser, wherein the annular aperture is used to reduce two beams of linearly polarized light into circular shapes and pass through the periphery of the condenser to obliquely irradiate the sample surface.

6. The optical film surface defect detection system according to claim 1, characterized in that: The signal of the photodetector PD (14) is: a signal of a light intensity signal of a light beam converted into an electrical signal, which is transmitted to the PC (24) for digital processing and spectrum calibration to determine the focusing state of the optical film; the signal of the CCD (23) is: a signal of an optical interference image formed by optical interference fringes collected by the CCD (23) converted into an electrical signal, which is transmitted to the PC for subsequent processing.

7. The optical film surface defect detection system according to claim 1, characterized in that: The data processing module also includes measurement software (26), and the measurement software (26) is used to detect defects in the optical interference image collected by the CCD (23).

8. The optical film surface defect detection system according to claim 7, characterized in that: The measuring software (26) is used to detect defects in the optical interference image collected by the CCD (23), specifically: using the YOLOv10 network to detect defects in the optical interference image.

9. The optical film surface defect detection system according to claim 8, characterized in that: The data processing module (6) further comprises a driver rotator (25), wherein the driver rotator (25) is used to adjust parameters of the measurement software (26) to control a three-dimensional displacement platform (19), wherein the three-dimensional displacement platform (19) is located below the microscope objective lens (18).

Images