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CN-120142333-B - Optical film surface defect detection system

CN120142333BCN 120142333 BCN120142333 BCN 120142333BCN-120142333-B

Abstract

The invention provides an optical film surface defect detection system which is particularly suitable for optical film, wafer and sensor detection. The system integrates six modules of illumination, confocal positioning, differential micro-interference, phase shift, imaging and data processing. The invention adopts a double-light-path imaging mode, namely a differential interference microscopic light path and a microscopic dark field imaging light path recorded by a CCD. The micro-dark field imaging optical path highlights the surface defects, particles and micro-nano structural features of the film by enhancing the surface scattering signals. The invention has the characteristics of simple structure, large single measurement range, high resolution, high precision and the like, effectively overcomes the defects of three-dimensional information deficiency, low efficiency, narrow application range, difficult positioning and the like of the traditional technology, and remarkably improves the detection efficiency and applicability.

Inventors

  • ZHANG YINGGE
  • SHAO WEI
  • GAO RUIPENG
  • Meng Yuechen
  • QIAN BOXING
  • TIAN LIANG
  • FANG WENJIN

Assignees

  • 西安理工大学

Dates

Publication Date
20260508
Application Date
20250324

Claims (9)

  1. 1. The optical film surface defect detection system is characterized by comprising an illumination module (1) and a first 1/4 wave plate (11), wherein the illumination module is used for forming a collimated light beam, and the collimated light beam passes through a polarizer (10) and forms circularly polarized light; The confocal positioning module (2) divides the circularly polarized light into two paths of linearly polarized light through a first polarization splitting prism (12) in the confocal positioning module, one path of light beam reaches a photoelectric detector PD (14) in the confocal positioning module through an imaging lens (13) in the confocal positioning module, and the other path of light beam enters the differential microscopic interference module (3); the differential micro interference module (3) is internally provided with a second polarization beam splitting prism (15) for splitting the other beam into an upper beam and a lower beam, the upper beam enters the phase shifting module (4), the lower beam irradiates the surface of the optical axis crystal (17) through the relay lens (16), the optical axis crystal (17) differentially shears the beam into two beams of linearly polarized light with mutually perpendicular vibration directions, the two beams of linearly polarized light are converged on the surface of an optical film through the micro objective lens (18) to form a reflected beam, the reflected beam is synthesized into a reflected beam after passing through the micro objective lens (18) and the optical axis crystal (17) again, the reflected beam is split into two paths of reflected beams again at the second polarization beam splitting prism (15), one path of reflected beam enters the phase shifting module (4), and the other path of reflected 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 for carrying out phase shift treatment on the upper beam and one path of reflected beam, and the treated beam enters the imaging module (5); the imaging module (5) comprises a Tube imaging lens (22) and a CCD (23), wherein the Tube imaging lens (22) is used for receiving one path of reflected light beam and one path of upper path of light beam after phase shifting to form interference fringes; the data processing module (6) comprises a PC (24), wherein the PC (24) is connected with the photo detector PD (14) and the CCD (23) and is used for receiving and processing signals from the photo detector PD (14) and signals of the CCD (23) so as to obtain information on the surface of the optical film.
  2. 2. An optical film surface defect detection system according to claim 1, characterized in that the illumination module (1) comprises a light source (7), a tunable attenuator (8) and a 4f beam shaping system (9) on the same horizontal axis, said light source being arranged to generate a light beam, the light beam being collimated by the tunable attenuator (8) and the 4f beam shaping system (9).
  3. 3. The system according to claim 1, wherein the first polarization splitting prism (12), the imaging lens (13) and the photodetector PD (14) of the confocal positioning module (2) are sequentially disposed in the detection light synthesizing device in the order from bottom to top and are located on the same horizontal axis.
  4. 4. The optical film surface defect detection system according to claim 1, wherein the second polarization splitting prism (15), the relay lens (16), the optical axis crystal (17) and the micro objective lens (18) of the differential micro interference module (3) are arranged in the order from top to bottom and are located on the same vertical axis.
  5. 5. The system according to claim 1, wherein the microscope objective (18) comprises an annular aperture for reducing two linearly polarized light beams to a circular shape and a condenser lens for obliquely irradiating the sample surface through the periphery of the condenser lens.
  6. 6. The system for detecting the surface defects of the optical film according to claim 1, wherein the signals of the photoelectric detector PD (14) are signals for converting light intensity signals of one beam into electric signals, the electric signals are transmitted to the PC (24) for digital processing and spectrum calibration to judge the focusing state of the optical film, and the signals of the CCD (23) are signals for converting optical interference images formed by optical interference fringes collected by the CCD (23) into electric signals, and the electric signals are transmitted to the PC for subsequent processing.
  7. 7. An optical film surface defect detection system according to claim 1, wherein the data processing module further comprises measurement software (26), said measurement software (26) being adapted to detect defects in the optical interference image acquired by the CCD (23).
  8. 8. The system for detecting surface defects of optical films according to claim 7, characterized in that the measurement software (26) is used for detecting defects of optical interference images acquired by the CCD (23), in particular, detecting defects of optical interference images by adopting YOLOv network.
  9. 9. An optical film surface defect detection system according to claim 8, wherein the data processing module (6) further comprises a driver rotator (25), the driver rotator (25) being adapted to adjust parameters of the measurement software (26) to control a three-dimensional displacement stage (19), the three-dimensional displacement stage (19) being located below the microscope objective (18).

Description

Optical film surface defect detection system Technical Field The invention relates to the technical field of precise optical detection, in particular to an optical film surface defect detection system. Background An optical film refers to a thin layer of material having specific optical properties that is coated or plated on an optical element or a separate substrate. The production and preparation of the optical film are affected by various factors, and the surface of the optical film is easy to generate various defects which affect the surface evenness and the original optical characteristics of the film. In order to ensure the quality of the optical film, it is often necessary to perform image acquisition and defect detection on the prepared film. In the current industrial production process, the traditional camera acquisition method is basically used for acquiring the optical film image, so that the optical film is subjected to spread shooting, the defect of unstable precision is caused, and the subsequent film defect identification effect is influenced. And only two-dimensional image information of the film can be obtained, and the acquisition of three-dimensional information on the surface of the film is difficult to realize through single detection. While contact modes such as a surface profiler, an atomic force microscope and the like can realize the surface three-dimensional information detection of the optical film, secondary damage is easily caused to the surface of the optical film. Chinese patent CN 113740034B also discloses an optical interference detection film, but it performs interference principle imaging only through the most basic optical system. The method does not use a microscope objective for accurate imaging, lacks a link for judging the focusing state of a detection sample, cannot realize high-precision image acquisition, performs subsequent detection only based on an acquired two-dimensional image, is too dependent on the training precision of a detection model, and lacks the real-time property of detection by using a basic improved convolutional neural network. Disclosure of Invention In order to solve the technical problems, the invention provides an optical film surface defect detection system. The two-dimensional and three-dimensional information acquisition of the film can be realized simultaneously, the reliability of the whole system is improved, and the labor intensity of measuring staff is reduced. In order to achieve the purpose of the invention, the technical scheme provided by the invention is as follows: An optical film surface defect detection system comprises an illumination module, a first 1/4 wave plate and a second 1/4 wave plate, wherein the illumination module is used for forming a collimated light beam, and the collimated light beam passes through the polarizer and the first 1/4 wave plate to form circularly polarized light; the confocal positioning module divides the circularly polarized light into two paths of linearly polarized light through a first polarization splitting prism in the confocal positioning module, one path of light beam reaches a photoelectric detector PD in the confocal positioning module through an imaging lens in the confocal positioning module, and the other path of light beam enters the differential microscopic interference module; The optical axis crystal differentially shears the light beam into two linearly polarized light beams with mutually perpendicular vibration directions, the two linearly polarized light beams converge on the surface of the optical film through the microscope objective lens to form a reflected light beam, the reflected light beam returns after passing through the microscope objective lens and the optical axis crystal again to form a reflected light beam, and the reflected light beam is divided into two paths of reflected light beams at the second polarization splitting prism again, wherein one path of reflected light beam enters the phase shifting module; The phase shift module is provided with a second 1/4 wave plate and an analyzer and is used for carrying out phase shift treatment on the upper beam and one path of reflected beam, and the treated beam enters the imaging module; The imaging module comprises a Tube imaging lens and a CCD, wherein the Tube imaging lens is used for receiving one path of reflected light beam and one path of upper path of light beam after phase shift to form interference fringes; The data processing module comprises a PC, wherein the PC is connected with the photo detector PD and the CCD and is used for receiving and processing signals from the photo detector PD and signals of the CCD so as to obtain information on the surface of the optical film. Further, the illumination module comprises a light source, a tunable attenuation sheet and a 4f beam shaping system on the same horizontal axis, the light source being arranged to generate a light beam, the light beam being collimated by