A lens surface micro-defect detection system based on laser scattering

Abstract

The application discloses a lens surface micro-defect detection system based on laser scattering, relates to the technical field of lens surface micro-defect detection, and comprises a light source emission module, a linear illumination module, a two-dimensional scanning module, a multi-angle scattering collection module, a signal conditioning module, a micro-defect judgment module, a closed-loop control module, a data management module and a display output module, wherein a light beam is emitted by the light source, is expanded and collimated, and is linearly focused to form a linear illumination spot; the two-dimensional scanning module drives the lens to step scan; scattered light signals are synchronously collected at multiple angles and are converted into electric signals; time splicing and space mapping are performed on the electric signals to generate multi-angle scattering intensity distribution data, according to which micro-defects are judged and types are identified; meanwhile, signal quality evaluation parameters generated according to the data are used to close-loop adjust the light source power and the scanning speed, a defect distribution map is generated, stored and rendered and output; and the application realizes adaptive detection of lens surface micro-defects through multi-angle scattering collection and closed-loop feedback.

Description

Technical Field

[0001] This invention relates to the field of micro-defect detection technology on lens surfaces, and in particular to a micro-defect detection system for lens surfaces based on laser scattering. Background Technology

[0002] During the grinding, polishing, and coating processes of optical lenses, micron-level defects such as scratches, pitting, and bubbles are easily generated on the surface. These micro-defects significantly reduce the optical performance of the lens, leading to light scattering, energy loss, and image quality degradation, and may even cause stress cracking during subsequent use. As the requirements for lens surface quality in precision optical systems continue to increase, high-throughput, high-sensitivity online detection of micro-defects on lens surfaces has become a critical step in the manufacturing process.

[0003] Existing methods for detecting defects on lens surfaces mainly fall into the following two categories:

[0004] First: Visual detection methods based on image sensing. These methods use area scan cameras or line scan cameras to acquire images of the lens surface and then use image processing algorithms to identify surface defects.

[0005] Second: Detection methods based on laser scattering. These methods utilize the scattering effect of defects on incident laser light and determine the presence or absence of defects by collecting the intensity of the scattered light signal.

[0006] For the second method, most detection systems only collect scattering signals from a single scattering angle (usually forward or lateral), lacking the ability to identify the spatial distribution differences of scattering for defects of different shapes (scratches, pits, bubbles), and thus failing to classify defects. Secondly, the lack of a timing synchronization mechanism between the scanning mechanism and signal acquisition leads to insufficient spatial positioning accuracy, making it difficult to generate an accurate spatial distribution map of defects. At the same time, the output power of the light source and the scanning speed remain constant during operation. When the reflectivity of the lens surface changes due to material differences or uneven coating, the illumination intensity and acquisition speed cannot be adaptively adjusted, resulting in poor detection consistency between different lenses. Therefore, this invention proposes a lens surface micro-defect detection system based on laser scattering to solve the problems existing in the prior art. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to propose a micro-defect detection system for lens surfaces based on laser scattering. This invention improves the ability to identify and classify defects of different morphologies (scratches, pits, bubbles), thereby solving the problems existing in the prior art.

[0008] To achieve the objectives of this invention, the invention is implemented through the following technical solution: a micro-defect detection system for lens surfaces based on laser scattering, comprising the following modules:

[0009] The light source emitting module is used to emit a detection laser beam;

[0010] The linear illumination module is used to receive the detection laser beam and perform beam expansion, collimation and linear focusing on the detection laser beam to form a linear illumination spot covering the surface of the lens to be tested;

[0011] The two-dimensional scanning module is used to drive the lens to perform two-dimensional step scanning motion relative to the linear illumination spot;

[0012] The multi-angle scattering acquisition module is used to simultaneously acquire scattered light signals generated by the surface of the lens under test from multiple preset scattering angles during the two-dimensional stepping scanning motion, and to perform photoelectric conversion processing on the scattered light signals to generate multi-channel scattered electrical signals.

[0013] The signal conditioning module is used to perform time synchronization splicing and spatial coordinate mapping processing on the multi-channel scattered electrical signals to generate multi-angle scattering intensity distribution data corresponding to each spatial position on the surface of the lens under test, and to generate signal quality evaluation parameters based on the multi-angle scattering intensity distribution data.

[0014] The micro-defect determination module is used to extract the scattering intensity distribution characteristics of each spatial location based on the multi-angle scattering intensity distribution data, and compare the scattering intensity distribution characteristics with the preset standard scattering characteristics to determine whether there are micro-defects at each spatial location.

[0015] The closed-loop control module receives signal quality evaluation parameters generated by the signal conditioning module, and sends power control commands to the light source emission module and scanning speed control commands to the two-dimensional scanning module based on the signal quality evaluation parameters.

[0016] The data management module is used to receive the judgment results output by the micro-defect judgment module, perform spatial coordinate calibration processing on the judgment results to generate a defect distribution map, and perform compression storage processing on the defect distribution map.

[0017] The display output module is used to receive the defect distribution map and perform visualization rendering processing on the defect distribution map to output a rendered defect distribution image.

[0018] A further improvement is that the light source emitting module includes:

[0019] Laser seed module, used to emit the initial laser beam;

[0020] The power drive submodule is used to receive power control commands and drive the laser seed submodule to adjust the output power of the initial laser beam according to the power control commands;

[0021] The temperature control submodule is used to collect the operating temperature of the laser seed submodule and perform closed-loop constant temperature control on the operating temperature.

[0022] The emitted light monitoring submodule is used to perform real-time monitoring of the power and pointing stability of the initial laser beam, and generate a spot failure flag signal when power fluctuations or pointing drifts exceed a preset threshold are detected.

[0023] A further improvement is that the linear lighting module includes:

[0024] The beam expanding and collimating submodule is used to expand the detection laser beam to increase its diameter and collimate the expanded laser beam to obtain a parallel laser beam.

[0025] The cylindrical focusing submodule is used to perform unidirectional linear focusing on a parallel laser beam to form a linear illumination spot.

[0026] The uniform shaping submodule is used to perform uniformization processing on the light intensity distribution on the cross-section of the linear illumination spot so that the light intensity non-uniformity of the linear illumination spot in the length direction is less than a preset uniformity threshold.

[0027] A further improvement is that the two-dimensional scanning module includes:

[0028] The lens carrier submodule is used to fix the lens and keep the surface of the lens to be tested perpendicular to the optical axis of the linear illumination spot.

[0029] The first mirror module is used to drive the lens-carrying submodule to perform stepping motion along the first horizontal direction;

[0030] The second mirror module is used to drive the lens carrier submodule to perform stepping motion along the second horizontal direction, where the first horizontal direction and the second horizontal direction are perpendicular to each other.

[0031] The synchronization control submodule is used to receive scanning speed control commands, generate stepping timing signals to drive the first and second oscillating mirror modules according to the scanning speed control commands, and output the stepping timing signals to the multi-angle scattering acquisition module as a time synchronization reference.

[0032] Further improvements include: the multi-angle scattering acquisition module includes:

[0033] The forward scattering acquisition submodule is used to acquire the first scattered light component from a first acquisition position that is deflected by a first preset angle relative to the transmission direction of the detection laser beam.

[0034] The side scattering acquisition submodule is used to acquire the second scattered light component from a second acquisition position that is deflected by a second preset angle relative to the transmission direction of the detection laser beam, wherein the second preset angle is greater than the first preset angle.

[0035] The backscattering acquisition submodule is used to acquire the third scattered light component from a third acquisition position deflected by a third preset angle relative to the transmission direction of the detection laser beam. The third preset angle is greater than the second preset angle.

[0036] The photoelectric conversion submodule is used to convert the first scattered light component, the second scattered light component, and the third scattered light component into a first electrical signal, a second electrical signal, and a third electrical signal, respectively.

[0037] The synchronous acquisition submodule is used to perform synchronous analog-to-digital conversion processing on the first, second, and third electrical signals according to the step timing signal, and generate synchronous digital scattering signals corresponding to each step position.

[0038] A further improvement is that the signal conditioning module includes:

[0039] The signal preprocessing submodule is used to perform baseline drift subtraction and noise filtering on the multi-channel scattered electrical signals.

[0040] The synchronous stitching submodule is used to stitch the pre-processed channel signals according to the scanning path sequence of the two-dimensional step scanning motion based on the acquisition timestamp of each spatial location, forming a row scattering intensity matrix corresponding to each scanning row of the lens surface to be tested.

[0041] The coordinate mapping submodule is used to rearrange the row scattering intensity matrix into multi-angle scattering intensity distribution data corresponding to the spatial grid of the surface to be measured on the lens, based on the step coordinates of each spatial location.

[0042] The quality evaluation submodule is used to calculate signal quality evaluation parameters based on the signal-to-noise ratio and dynamic range of multi-angle scattering intensity distribution data.

[0043] A further improvement is that the micro-defect determination module includes:

[0044] The reference storage submodule is used to store preset standard scattering characteristics, which include standard scattering intensity distribution and standard scattering angle response curve.

[0045] The feature extraction submodule is used to perform multi-dimensional feature calculation processing on the scattering intensity at each spatial location in the multi-angle scattering intensity distribution data to obtain the scattering intensity distribution features. The multi-dimensional features include the peak value of scattering intensity at each angle, the integral area of ​​scattering intensity at each angle, and the ratio of scattering intensity at multiple angles.

[0046] The difference calculation submodule is used to calculate the difference metric between the scattering intensity distribution characteristics and the preset standard scattering characteristics.

[0047] The threshold determination submodule is used to compare the difference measurement value with the preset defect determination threshold. When the difference measurement value is greater than the preset defect determination threshold, it is determined that there is a micro defect at the current spatial location; otherwise, it is determined that there is no defect at the current spatial location.

[0048] The type identification submodule is used to determine the defect type of a micro-defect when it is determined that there is a micro-defect, based on the relative ratio of the scattering intensity of each angle in the multi-angle scattering intensity distribution data. The defect types include scratch defects, pitting defects, and bubble defects.

[0049] A further improvement is that the closed-loop control module includes:

[0050] The parameter receiving submodule is used to receive signal quality evaluation parameters output by the signal conditioning module;

[0051] The power decision submodule is used to calculate the power adjustment amount based on the signal-to-noise ratio value in the signal quality evaluation parameters, and generate power control commands based on the power adjustment amount.

[0052] The speed decision submodule is used to calculate the speed adjustment amount based on the dynamic range value in the signal quality evaluation parameters, and generate a scan speed control command based on the speed adjustment amount.

[0053] The instruction output submodule is used to output power control instructions to the light source emission module and scan speed control instructions to the two-dimensional scanning module.

[0054] A further improvement is that the data management module includes:

[0055] The coordinate calibration submodule is used to map the micro-defect judgment results output by the micro-defect judgment module to the global spatial coordinate system based on the step coordinates of each spatial position of the two-dimensional step scanning motion and the initial positioning coordinates of the lens to obtain the absolute spatial coordinates of each micro-defect.

[0056] The distribution map generation submodule is used to generate a defect distribution map based on the absolute spatial coordinates of each micro-defect and the judgment result. Each defect point in the defect distribution map carries a defect type label.

[0057] The compressed storage submodule is used to perform run-length encoding compression on the defect distribution map to obtain compressed defect data, and to perform disk write storage on the compressed defect data.

[0058] A further improvement is that the display output module includes:

[0059] The rendering processing submodule is used to receive the defect distribution map, map each defect point in the defect distribution map to a different color label according to the defect type, and perform image scaling processing on the mapped defect distribution map to obtain a rendered defect distribution image.

[0060] The display driver submodule is used to receive the rendering defect distribution image and drive the external display device to perform image display.

[0061] The report generation submodule is used to calculate the total number of defects, the number of each defect type, and the percentage of defect area based on the defect distribution map, and to generate a statistical report of the detection results based on the statistical results.

[0062] The beneficial effects of this invention are as follows:

[0063] (1) By setting up a multi-angle scattering acquisition module, the present invention can simultaneously acquire scattered light signals from three preset angles: forward, side and back, and obtain the complete scattering distribution characteristics of micro-defects in space. Compared with the single-angle acquisition method, it greatly improves the ability to identify and classify defects of different shapes.

[0064] (2) By setting up a synchronization control submodule to generate step timing signals and output them to the multi-angle scattering acquisition module, the present invention ensures that the signal acquisition of each scattering angle and the two-dimensional step scanning motion are strictly synchronized in time, thus ensuring the accurate correspondence between each spatial position and the scattering signal. This fundamentally solves the problem of spatiotemporal mismatch between scanning motion and signal acquisition, and significantly improves the spatial positioning accuracy of defects.

[0065] (3) By setting up a quality evaluation sub-module in the closed-loop control module and the signal conditioning module, the present invention constructs a complete closed-loop feedback control link, realizes adaptive optimization of detection parameters, and ensures detection consistency between lenses with different reflectivities. Attached Figure Description

[0066] Figure 1 This is a schematic diagram of the system module architecture of the present invention.

[0067] Figure 2 This is a schematic diagram of the optical path principle of the linear lighting module of the present invention.

[0068] Figure 3 This is a schematic diagram of the multi-angle scattering acquisition location layout of the present invention. Detailed Implementation

[0069] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0070] according to Figures 1-3 As shown, this embodiment provides a micro-defect detection system for lens surfaces based on laser scattering, which includes, in sequence along the signal flow direction, a light source emission module, a linear illumination module, a two-dimensional scanning module, a multi-angle scattering acquisition module, a signal conditioning module, a micro-defect judgment module, a closed-loop control module, a data management module, and a display output module.

[0071] The output end of the light source emitting module is optically coupled to the incident end of the linear illumination module; the output end of the linear illumination module is positioned towards the surface to be measured on the lens of the two-dimensional scanning module; the acquisition end of the multi-angle scattering acquisition module is positioned towards the surface to be measured on the lens, and the signal output end of the multi-angle scattering acquisition module is electrically connected to the signal input end of the signal conditioning module; the first signal output end of the signal conditioning module is electrically connected to the signal input end of the micro-defect judgment module, and the second signal output end of the signal conditioning module is electrically connected to the signal input end of the closed-loop control module; the judgment result output end of the micro-defect judgment module is electrically connected to the signal input ends of the data management module and the display output module, respectively; the first control output end of the closed-loop control module is communicatively connected to the control input end of the light source emitting module, and the second control output end of the closed-loop control module is communicatively connected to the control input end of the two-dimensional scanning module.

[0072] The overall workflow is as follows, including the following steps:

[0073] Step 1: Detecting Laser Beam Emission and Illumination: The light source emission module includes a laser seed submodule, a power drive submodule, a temperature control submodule, and an emitted light monitoring submodule. The laser seed submodule emits an initial laser beam; the power drive submodule adjusts the emission power of the initial laser beam according to the received power control command; the temperature control submodule collects the operating temperature of the laser seed submodule and performs closed-loop constant temperature control to ensure that the laser seed submodule operates in a stable thermal environment and avoids temperature drift that causes fluctuations in emission wavelength and power; the emitted light monitoring submodule performs real-time monitoring of the power and pointing stability of the initial laser beam. When the power fluctuation amplitude within a unit time exceeds a preset fluctuation threshold, or the beam pointing angle deviation exceeds a preset pointing threshold, the emitted light monitoring submodule generates a spot failure flag signal and reports it to the system host computer.

[0074] After being emitted from the light source emitting module, the detection laser beam enters the linear illumination module. The linear illumination module includes a beam expanding and collimating submodule, a cylindrical focusing submodule, and a uniform shaping submodule. The beam expanding and collimating submodule expands the detection laser beam to increase its diameter and then collimates it to obtain a parallel laser beam. The cylindrical focusing submodule performs unidirectional linear focusing on the parallel laser beam, maintaining a constant beam width in the first horizontal direction while compressing the beam to a sub-millimeter width in the second horizontal direction perpendicular to the first horizontal direction, thus forming a linear illumination spot. Specifically, the length of the linear illumination spot covers the entire aperture of the lens surface under test, and its width is on the order of micrometers to sub-millimeters. The uniform shaping submodule homogenizes the light intensity distribution across the cross-section of the linear illumination spot, ensuring that the light intensity non-uniformity along the length of the linear illumination spot is less than a preset uniformity threshold, thereby guaranteeing consistent illumination intensity at all locations on the lens surface under test during scanning.

[0075] Step 2: Two-dimensional scanning motion of the lens: The two-dimensional scanning module includes a lens-carrying submodule, a first oscillating mirror module, a second oscillating mirror module, and a synchronization control submodule. The lens-carrying submodule fixes the lens and keeps the surface of the lens to be measured perpendicular to the optical axis of the linear illumination spot; the first oscillating mirror module drives the lens-carrying submodule to perform stepping motion along a first horizontal direction; the second oscillating mirror module drives the lens-carrying submodule to perform stepping motion along a second horizontal direction, the first horizontal direction and the second horizontal direction being perpendicular to each other; specifically, in a complete scan, the two-dimensional scanning module first drives the lens to step at a constant speed along the first horizontal direction, completes one line scan, then steps one line spacing along the second horizontal direction, and then performs the next line scan in the opposite direction of the first horizontal direction, and so on, until the linear illumination spot covers the entire area of ​​the surface of the lens to be measured.

[0076] During the scanning process, the synchronization control submodule receives the scanning speed control command from the closed-loop control module, and adjusts the single-step dwell time and line switching time of the stepping motion in real time according to the scanning speed control command, generates the stepping timing signal to drive the first and second vibrating mirror modules, and outputs the stepping timing signal to the multi-angle scattering acquisition module as a time synchronization reference.

[0077] Step 3: Synchronous Acquisition of Multi-Angle Scattering Signals: During each step position of the two-dimensional stepping scanning motion, a linear illumination spot illuminates the current spatial position of the surface under test on the lens. When micro-defects (such as scratches, pits, or bubbles) exist at this spatial position, the micro-defects produce a scattering effect on the incident laser, emitting scattered light in different directions.

[0078] The multi-angle scattering acquisition module includes a forward scattering acquisition submodule, a side scattering acquisition submodule, a backscattering acquisition submodule, a photoelectric conversion submodule, and a synchronous acquisition submodule, specifically:

[0079] The forward scattering acquisition submodule acquires the first scattered light component from a first acquisition position that is deflected by a first preset angle relative to the transmission direction of the detection laser beam. Correspondingly, the first preset angle is a range of 5° to 30° relative to the transmission direction. Scattered light within this angle range is sensitive to scratch-like defects.

[0080] The lateral scattering acquisition submodule acquires the second scattered light component from a second acquisition position that is deflected by a second preset angle relative to the transmission direction of the detection laser beam. The second preset angle is greater than the first preset angle. Correspondingly, the second preset angle is in the range of 40° to 80° relative to the transmission direction. The scattered light in this angle range is sensitive to pitting defects.

[0081] The backscattering acquisition submodule acquires the third scattered light component from a third acquisition position deflected by a third preset angle relative to the transmission direction of the detection laser beam. The third preset angle is greater than the second preset angle. Correspondingly, the third preset angle is a range of 120° to 165° in the opposite direction of the incident direction. The scattered light within this angle range has a high response sensitivity to bubble-like defects on the surface and subsurface of the lens.

[0082] The photoelectric conversion submodule converts the first scattered light component, the second scattered light component, and the third scattered light component into a first electrical signal, a second electrical signal, and a third electrical signal, respectively.

[0083] The synchronous acquisition submodule performs synchronous analog-to-digital conversion on the first, second, and third electrical signals based on the step timing signals. Specifically, the rising edge of each step timing signal triggers a synchronous acquisition action, and the three channels are sampled simultaneously at the same time, generating a synchronous digital scattering signal corresponding to the current step position. This synchronous digital scattering signal contains complete scattering intensity information of the same spatial location at three different scattering angles.

[0084] Step 4, Signal Conditioning and Data Generation: The synchronous digital scattering signal (i.e., multi-channel scattering electrical signal) is sent to the signal conditioning module, which includes a signal preprocessing submodule, a synchronous splicing submodule, a coordinate mapping submodule, and a quality evaluation submodule.

[0085] The signal preprocessing submodule performs baseline drift subtraction and noise filtering on the multi-channel scattered electrical signals. The noise filtering uses a digital low-pass filter to remove high-frequency electronic noise, and the baseline drift subtraction uses a sliding window averaging method to subtract the dark current background of the detection channel.

[0086] The preprocessed signals from each channel then enter the synchronous stitching submodule. This submodule, based on the acquisition timestamps at each spatial location—that is, the rising edge of the step timing signal corresponding to each step position—performs end-to-end stitching of the preprocessed channel signals according to the scanning path sequence of the two-dimensional stepping scan motion. Specifically, for each scan line, the scattering intensity data of all step positions in that line are arranged sequentially according to the stepping order, forming a row scattering intensity matrix corresponding to each scan line.

[0087] The row scattering intensity matrix is ​​further fed into the coordinate mapping submodule. The coordinate mapping submodule then rearranges the row scattering intensity matrix into multi-angle scattering intensity distribution data corresponding to the spatial grid of the lens's test surface, based on the step coordinates of each spatial location (i.e., the step number in the first horizontal direction and the row number in the second horizontal direction). This multi-angle scattering intensity distribution data is a three-dimensional data matrix, where the first and second dimensions correspond to the spatial coordinates of the lens's test surface in two horizontal directions, respectively, and the third dimension corresponds to the intensity values ​​at three scattering angles.

[0088] Meanwhile, the quality evaluation submodule calculates signal quality evaluation parameters based on the generated multi-angle scattering intensity distribution data. Specifically, the quality evaluation submodule calculates the ratio of the signal mean to the standard deviation at all effective spatial locations in the multi-angle scattering intensity distribution data as the signal-to-noise ratio (SNR) value, and calculates the span between the maximum and minimum intensity values ​​in the multi-angle scattering intensity distribution data as the dynamic range value. The signal quality evaluation parameters, including the SNR value and the dynamic range value, are output as feedback signals to the closed-loop control module.

[0089] Step 5: Micro-defect feature detection and judgment: Multi-angle scattering intensity distribution data enters the micro-defect judgment module from the signal conditioning module. This module includes a benchmark storage submodule, a feature extraction submodule, a difference calculation submodule, a threshold judgment submodule, and a defect type identification submodule.

[0090] The reference storage submodule stores preset standard scattering characteristics, including standard scattering intensity distribution and standard scattering angle response curve. Specifically, the standard scattering intensity distribution is obtained by statistically averaging the scattering intensity of multiple defect-free standard lenses at multiple spatial locations; the standard scattering angle response curve records the typical scattering intensity ratios of the defect-free surface at three angles: forward, side, and back.

[0091] The feature extraction submodule performs multidimensional feature calculations on the scattering intensity at each spatial location in the multi-angle scattering intensity distribution data to obtain the scattering intensity distribution features. For each spatial location, the feature extraction submodule extracts the peak value of scattering intensity at each angle and the integral area of ​​scattering intensity at each angle from the forward, lateral, and backward angle channels, and calculates the ratio of scattering intensity at multiple angles, which together constitute the scattering intensity distribution features of that spatial location.

[0092] The difference calculation submodule calculates the difference metric between the scattering intensity distribution characteristics and the preset standard scattering characteristics. Specifically, the difference metric uses Euclidean distance or Mahalanobis distance as the metric.

[0093] The threshold determination submodule compares the difference metric value with a preset defect determination threshold. If the difference metric value is greater than the preset defect determination threshold, a micro-defect is determined to exist at the current spatial location; otherwise, no defect is determined at the current spatial location. When a micro-defect is determined to exist, the defect type identification submodule determines the defect type of the micro-defect based on the relative ratio of the scattering intensity at each angle in the multi-angle scattering intensity distribution data. Specifically, if the forward scattering intensity is significantly higher than the side and back scattering intensity, it is determined to be a scratch defect; if the side scattering intensity is dominant and the intensity distribution at the three angles is relatively dispersed, it is determined to be a pitting defect; if the back scattering intensity is significantly enhanced relative to the forward and side scattering intensity, it is determined to be a bubble defect.

[0094] Step 6: Closed-loop feedback control: During system operation, the closed-loop control module continuously receives signal quality evaluation parameters generated by the signal conditioning module. This module includes a parameter receiving submodule, a power decision submodule, a speed decision submodule, and a command output submodule.

[0095] The parameter receiving submodule receives signal quality evaluation parameters output by the signal conditioning module. The power decision submodule calculates the power adjustment amount based on the signal-to-noise ratio (SNR) value in the signal quality evaluation parameters and generates a power control command based on the power adjustment amount. Specifically, when the SNR value is lower than the preset lower limit, the power decision submodule determines that the current illumination intensity is insufficient and calculates a positive power adjustment amount to increase the output power of the light source emitting module; when the SNR value is higher than the preset upper limit, the power decision submodule determines that the current illumination intensity is excessive and calculates a negative power adjustment amount to reduce the output power, avoiding damage to the lens surface or saturation of the detector by strong light.

[0096] The speed decision submodule calculates the speed adjustment amount based on the dynamic range value in the signal quality evaluation parameters, and generates a scan speed control command based on the speed adjustment amount. Specifically, when the dynamic range value is too narrow, it indicates insufficient signal contrast. The speed decision submodule determines that the current scan speed is too fast, resulting in insufficient integration time, and calculates a negative speed adjustment amount to reduce the scan speed and extend the dwell time at each step position. When the dynamic range value is sufficient and the system detection throughput requirement is high, the speed decision submodule calculates a positive speed adjustment amount to appropriately increase the scan speed.

[0097] The command output submodule outputs power control commands to the light source emission module and scanning speed control commands to the two-dimensional scanning module, thus forming a complete closed-loop control link.

[0098] Step 7: Data Management and Result Display: The judgment results output by the micro-defect judgment module (including whether there are defects at each spatial location, the type of defects, and the corresponding scattering intensity data) are sent to the data management module and the display output module, which include a coordinate calibration submodule, a distribution map generation submodule, and a compressed storage submodule.

[0099] The coordinate calibration submodule maps the micro-defect judgment results output by the micro-defect judgment module to the global spatial coordinate system based on the step coordinates of each spatial position of the two-dimensional step scanning motion and the initial positioning coordinates of the lens to obtain the absolute spatial coordinates of each micro-defect.

[0100] The distribution map generation submodule generates a defect distribution map based on the absolute spatial coordinates of each micro-defect and the judgment result. Each defect point in the defect distribution map carries a defect type label.

[0101] The compressed storage submodule performs run-length encoding compression on the defect distribution map to obtain compressed defect data. For defect distribution maps containing a large number of defect-free areas, run-length encoding can represent continuous background areas with a very small amount of data, thereby significantly compressing the data volume. The compressed storage submodule then performs disk write storage processing on the compressed defect data.

[0102] The display output module includes a rendering processing submodule, a display driver submodule, and a report generation submodule.

[0103] The rendering processing submodule receives the defect distribution map, maps each defect point in the defect distribution map to a different color identifier according to the defect type, and performs image scaling processing on the mapped defect distribution map to obtain a rendered defect distribution image. Specifically, scratch defects can be mapped to red, pitted defects to yellow, and bubble defects to blue.

[0104] The display driver submodule receives the rendered defect distribution image and drives the external display device to perform image display.

[0105] The report generation submodule calculates the total number of defects, the number of each defect type, and the percentage of defect area based on the defect distribution map, and generates a statistical report of the detection results for operators to review and archive.

[0106] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the present invention without departing from its framework and scope of application, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for detecting micro-defects on the surface of a lens based on laser scattering, characterized in that: Includes the following modules: The light source emitting module is used to emit a detection laser beam; The linear illumination module is used to receive the detection laser beam and perform beam expansion, collimation and linear focusing on the detection laser beam to form a linear illumination spot covering the surface of the lens to be tested; The two-dimensional scanning module is used to drive the lens to perform two-dimensional step scanning motion relative to the linear illumination spot; The multi-angle scattering acquisition module is used to simultaneously acquire scattered light signals generated by the surface of the lens under test from multiple preset scattering angles during the two-dimensional stepping scanning motion, and to perform photoelectric conversion processing on the scattered light signals to generate multi-channel scattered electrical signals. The signal conditioning module is used to perform time synchronization splicing and spatial coordinate mapping processing on the multi-channel scattered electrical signals to generate multi-angle scattering intensity distribution data corresponding to each spatial position on the surface of the lens under test, and to generate signal quality evaluation parameters based on the multi-angle scattering intensity distribution data. The micro-defect determination module is used to extract the scattering intensity distribution characteristics of each spatial location based on the multi-angle scattering intensity distribution data, and compare the scattering intensity distribution characteristics with the preset standard scattering characteristics to determine whether there are micro-defects at each spatial location. The closed-loop control module receives signal quality evaluation parameters generated by the signal conditioning module, and sends power control commands to the light source emission module and scanning speed control commands to the two-dimensional scanning module based on the signal quality evaluation parameters. The data management module is used to receive the judgment results output by the micro-defect judgment module, perform spatial coordinate calibration processing on the judgment results to generate a defect distribution map, and perform compression storage processing on the defect distribution map. The display output module is used to receive the defect distribution map and perform visualization rendering processing on the defect distribution map to output a rendered defect distribution image.

2. The system for detecting micro-defects on a lens surface based on laser scattering according to claim 1, characterized in that: The light source emitting module includes: Laser seed module, used to emit the initial laser beam; The power drive submodule is used to receive power control commands and drive the laser seed submodule to adjust the output power of the initial laser beam according to the power control commands; The temperature control submodule is used to collect the operating temperature of the laser seed submodule and perform closed-loop constant temperature control on the operating temperature. The emitted light monitoring submodule is used to perform real-time monitoring of the power and pointing stability of the initial laser beam, and generate a spot failure flag signal when power fluctuations or pointing drifts exceed a preset threshold are detected.

3. The system for detecting micro-defects on a lens surface based on laser scattering according to claim 1, characterized in that: The linear lighting module includes: The beam expanding and collimating submodule is used to expand the detection laser beam to increase its diameter and collimate the expanded laser beam to obtain a parallel laser beam. The cylindrical focusing submodule is used to perform unidirectional linear focusing on a parallel laser beam to form a linear illumination spot. The uniform shaping submodule is used to perform uniformization processing on the light intensity distribution on the cross-section of the linear illumination spot so that the light intensity non-uniformity of the linear illumination spot in the length direction is less than a preset uniformity threshold.

4. The micro-defect detection system for lens surface based on laser scattering according to claim 1, characterized in that: The two-dimensional scanning module includes: The lens carrier submodule is used to fix the lens and keep the surface of the lens to be tested perpendicular to the optical axis of the linear illumination spot. The first mirror module is used to drive the lens-carrying submodule to perform stepping motion along the first horizontal direction; The second mirror module is used to drive the lens carrier submodule to perform stepping motion along the second horizontal direction, where the first horizontal direction and the second horizontal direction are perpendicular to each other. The synchronization control submodule is used to receive scanning speed control commands, generate stepping timing signals to drive the first and second oscillating mirror modules according to the scanning speed control commands, and output the stepping timing signals to the multi-angle scattering acquisition module as a time synchronization reference.

5. The micro-defect detection system for lens surface based on laser scattering according to claim 1, characterized in that: The multi-angle scattering acquisition module includes: The forward scattering acquisition submodule is used to acquire the first scattered light component from a first acquisition position that is deflected by a first preset angle relative to the transmission direction of the detection laser beam. The side scattering acquisition submodule is used to acquire the second scattered light component from a second acquisition position that is deflected by a second preset angle relative to the transmission direction of the detection laser beam, wherein the second preset angle is greater than the first preset angle. The backscattering acquisition submodule is used to acquire the third scattered light component from a third acquisition position deflected by a third preset angle relative to the transmission direction of the detection laser beam. The third preset angle is greater than the second preset angle. The photoelectric conversion submodule is used to convert the first scattered light component, the second scattered light component, and the third scattered light component into a first electrical signal, a second electrical signal, and a third electrical signal, respectively. The synchronous acquisition submodule is used to perform synchronous analog-to-digital conversion processing on the first, second, and third electrical signals according to the step timing signal, and generate synchronous digital scattering signals corresponding to each step position.

6. The micro-defect detection system for lens surface based on laser scattering according to claim 1, characterized in that: The signal conditioning module includes: The signal preprocessing submodule is used to perform baseline drift subtraction and noise filtering on the multi-channel scattered electrical signals. The synchronous stitching submodule is used to stitch the pre-processed channel signals according to the scanning path sequence of the two-dimensional step scanning motion based on the acquisition timestamp of each spatial location, forming a row scattering intensity matrix corresponding to each scanning row of the lens surface to be tested. The coordinate mapping submodule is used to rearrange the row scattering intensity matrix into multi-angle scattering intensity distribution data corresponding to the spatial grid of the surface to be measured on the lens, based on the step coordinates of each spatial location. The quality evaluation submodule is used to calculate signal quality evaluation parameters based on the signal-to-noise ratio and dynamic range of multi-angle scattering intensity distribution data.

7. The micro-defect detection system for lens surface based on laser scattering according to claim 1, characterized in that: The micro-defect determination module includes: The reference storage submodule is used to store preset standard scattering characteristics, which include standard scattering intensity distribution and standard scattering angle response curve. The feature extraction submodule is used to perform multi-dimensional feature calculation processing on the scattering intensity at each spatial location in the multi-angle scattering intensity distribution data to obtain the scattering intensity distribution features. The multi-dimensional features include the peak value of scattering intensity at each angle, the integral area of ​​scattering intensity at each angle, and the ratio of scattering intensity at multiple angles. The difference calculation submodule is used to calculate the difference metric between the scattering intensity distribution characteristics and the preset standard scattering characteristics. The threshold determination submodule is used to compare the difference measurement value with the preset defect determination threshold. When the difference measurement value is greater than the preset defect determination threshold, it is determined that there is a micro defect at the current spatial location; otherwise, it is determined that there is no defect at the current spatial location. The type identification submodule is used to determine the defect type of a micro-defect when it is determined that there is a micro-defect, based on the relative ratio of the scattering intensity of each angle in the multi-angle scattering intensity distribution data. The defect types include scratch defects, pitting defects, and bubble defects.

8. The micro-defect detection system for lens surface based on laser scattering according to claim 1, characterized in that: The closed-loop control module includes: The parameter receiving submodule is used to receive signal quality evaluation parameters output by the signal conditioning module; The power decision submodule is used to calculate the power adjustment amount based on the signal-to-noise ratio value in the signal quality evaluation parameters, and generate power control commands based on the power adjustment amount. The speed decision submodule is used to calculate the speed adjustment amount based on the dynamic range value in the signal quality evaluation parameters, and generate a scan speed control command based on the speed adjustment amount. The instruction output submodule is used to output power control instructions to the light source emission module and scan speed control instructions to the two-dimensional scanning module.

9. The micro-defect detection system for lens surface based on laser scattering according to claim 1, characterized in that: The data management module includes: The coordinate calibration submodule is used to map the micro-defect judgment results output by the micro-defect judgment module to the global spatial coordinate system based on the step coordinates of each spatial position of the two-dimensional step scanning motion and the initial positioning coordinates of the lens to obtain the absolute spatial coordinates of each micro-defect. The distribution map generation submodule is used to generate a defect distribution map based on the absolute spatial coordinates of each micro-defect and the judgment result. Each defect point in the defect distribution map carries a defect type label. The compressed storage submodule is used to perform run-length encoding compression on the defect distribution map to obtain compressed defect data, and to perform disk write storage on the compressed defect data.

10. The micro-defect detection system for lens surface based on laser scattering according to claim 1, characterized in that: The display output module includes: The rendering processing submodule is used to receive the defect distribution map, map each defect point in the defect distribution map to a different color label according to the defect type, and perform image scaling processing on the mapped defect distribution map to obtain a rendered defect distribution image. The display driver submodule is used to receive the rendering defect distribution image and drive the external display device to perform image display. The report generation submodule is used to calculate the total number of defects, the number of each defect type, and the percentage of defect area based on the defect distribution map, and to generate a statistical report of the detection results based on the statistical results.

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