阅读说明：本技术 一种光学元件缺陷检测系统及检测方法 (Optical element defect detection system and detection method ) 是由 袁志刚 郑楠 李洁 陈贤华 韦前才 周炼 赵世杰 邓文辉 钟波 侯晶 于 2021-09-17 设计创作，主要内容包括：本发明公开了一种光学元件缺陷检测系统及检测方法,包括床身支撑模块、隔振模块、定位夹持模块、缺陷检测模块、缺陷分析模块、扫描运动模块和电气控制模块,每个模块完成相应的功能,具体工作步骤包括：开启设备及软件、系统初始化设置、设置系统参数、放置被测样品、设置测量参数、样品扫描测试、检测数据采集、缺陷类型分析、缺陷特性评价和结果输出系统关闭。本发明解决了人工检验可能由于某些人员原因导致的缺陷形貌误判和缺陷定位错误,降低了缺陷定位错误发生率,进一步提高了大口径光学元器件的缺陷检测准确率。(The invention discloses an optical element defect detection system and a detection method, which comprises a lathe bed supporting module, a vibration isolation module, a positioning clamping module, a defect detection module, a defect analysis module, a scanning motion module and an electrical control module, wherein each module completes corresponding functions, and the specific working steps comprise: starting equipment and software, initializing and setting a system, setting system parameters, placing a tested sample, setting measurement parameters, scanning and testing the sample, acquiring detection data, analyzing defect types, evaluating defect characteristics and closing a result output system. The invention solves the problems of false judgment of defect appearance and false positioning of defects caused by some personnel reasons in manual inspection, reduces the occurrence rate of false positioning of defects and further improves the accuracy rate of defect detection of large-caliber optical components.)

1. An optical element defect detection system specifically comprises the following modules:

the positioning and clamping module (105) is used for positioning and clamping a test sample piece and automatically adjusting the posture of the test sample piece;

the defect detection module (104) is used for detecting and recording the defects of the test sample piece through laser scattering scanning and high-power objective imaging;

the defect analysis module (103) is used for carrying out classification statistics on the defects through a defect background removal algorithm and a defect characteristic identification contrast classification flow;

the scanning motion module (102) is used for carrying the defect detection module (104) and testing and splicing the whole surface of the large-caliber test sample piece; the splicing means that a plurality of small area tests in the test process of the large-caliber sample piece are spliced through a splicing algorithm to realize the display of the large-caliber full range;

and the electrical control module (101) is used for controlling the motion of the scanning motion module (102) and the test of the test sample piece.

2. The optical element defect detection system of claim 1, wherein a laser emission test system and a high power microscope are arranged in the defect detection module (104) for bright field imaging and detail confirmation after defect positions are determined by scattering test; the laser emission testing system comprises a laser emitter, a laser power adjusting device, a beam shaping module, a light polarization control module, a beam focusing module, a laser scattering detection module, a laser scattering collection module and a reflection light control module.

3. A defect detection method of an optical element defect detection system according to claims 1-2, characterized by comprising the steps of:

the method comprises the following steps: performing sample scanning test, namely performing two-dimensional scanning on a test sample piece by using a laser beam to form a defect statistical table and a defect distribution schematic diagram;

step two: acquiring detection data, and performing high-magnification microscopic imaging and size judgment on the defects according to all the defects or selected defect position coordinates obtained in the first step;

step three: analyzing the defect type, and performing classification statistics on the defects through a defect background removal algorithm and a defect characteristic identification contrast classification flow;

step four: and C, evaluating the defect characteristics, namely analyzing and evaluating the defects classified in the step three according to the defect judgment conditions and requirements.

4. The defect detection method of claim 3, wherein sample attitude adjustment is required before the sample scan test, and specifically comprises: and adjusting the pitching inclination state of the sample piece according to the automatic focusing definition under the high-power objective lens, wherein the high-power objective lens judges whether the posture of the sample piece forms a specified fixed included angle with the test light path by adopting a four-corner position judgment method and a four-edge and center position imaging judgment method.

5. The defect detection method of claim 3, wherein the sample scanning test uses a composite test method combining laser light scattering and high power imaging.

6. The defect detection method of claim 3, wherein the defect type analysis specifically comprises: removing background signals from defect scattering signals collected through the sample scanning test; extracting characteristic peak values through frequency conversion; judging the severity of the defect according to the height of the peak value; judging the shape and size of the defect according to the peak value integral area, and correspondingly determining the position of the defect according to the peak value position.

7. The defect detection method of claim 3, wherein the sample scan testing step specifically comprises: an incident laser beam is incident to the surface of a test sample piece at a given angle, the incident laser beam performs two-dimensional scanning operation in the transmission process, a detector performs real-time response to obtain a defect scattering signal, then a high-power objective lens images the positioned defect, and a two-dimensional scattering image of the surface defect is formed through the two-dimensional scanning operation.

8. The defect detection method of claim 7, wherein the defect scatter signals are divided into three types: background signal, background signal noise fluctuations and defect essence signal; the defect essential signal generates a peak value at the defect, and the defect is extracted by setting a defect signal threshold.

9. The method of claim 3, wherein the range of apertures for testing the test element for defects includes 30mm x 30mm-1500mm x500 mm.

Technical Field

The invention relates to the field of ultra-precision machining and detection of optical elements, in particular to a micron/submicron defect test in the polishing process and after finishing of a large-caliber optical element.

Background

The rapid development of modern large-scale optical engineering places severe demands on the processing quality of optical components. In particular, in the manufacturing process of the large-caliber optical element, an inspection process is required to detect defects on the polished surface of the optical element so as to improve the processing yield of the optical element, and the requirements of large caliber, high surface shape precision, super smoothness and low defect are required. The inspection process may be divided into an equipment inspection process and a manual inspection process according to the difference of the inspection subjects. The equipment inspection process is mainly used for machining small-caliber sample pieces in the same process. The manual inspection process requires an inspector to determine the morphological characteristics of the defect while using an inspection tool and manually identify the defect, and the process depends heavily on the experience of the inspector. Although the defects can be found in time by manual inspection, the finished product yield of the optical element is greatly improved, in the manual inspection process, the defect appearance misjudgment, the defect positioning error and the like caused by some artificial reasons inevitably occur.

Therefore, how to improve the defect detection accuracy of the large-aperture optical component and reduce the occurrence rate of defect positioning errors is a problem to be solved urgently at present.

Disclosure of Invention

The present invention addresses the above-described present and existing problems and provides a system and method for detecting defects in an optical element.

In order to achieve the purpose, the invention adopts the following technical scheme:

an optical element defect detection system specifically comprises the following modules:

the positioning and clamping module is used for positioning and clamping a test sample piece and automatically adjusting the posture of the test sample piece;

the defect detection module is used for detecting and recording the defects of the test sample piece through laser scattering scanning and high-power objective imaging;

the defect analysis module is used for carrying out classification statistics on the defects through a defect background removal algorithm and a defect characteristic identification contrast classification flow and issuing a detailed test result;

the scanning motion module is used for carrying the defect detection module and testing and splicing the whole surface of the large-caliber test sample piece; the splicing means that a plurality of small area tests in the test process of the large-caliber sample piece are spliced through a splicing algorithm to realize the display of the large-caliber full range;

and the electrical control module is used for controlling the motion of the scanning motion module and the test of the test sample piece.

Preferably, the defect detection module is provided with a laser emission detection system and a high power microscope.

Preferably, the laser emission detection system includes a laser emitter, a laser power adjusting device, a beam shaping module, a light polarization control module, a beam focusing module, a laser scattering detection module, a laser scattering collection module, and a reflection light control module.

Preferably, the electrical appliance control module is further configured to perform feedback processing on the sensor signal, and the like, so as to ensure that the device operates normally according to the instruction.

Preferably, the test system further comprises a bed support module which is positioned on the bottom layer of the whole system and is used for supporting the rest modules of the system and placing the test samples.

Preferably, the testing device further comprises a vibration isolation module located above the bed body supporting module, the electrical control module, the scanning motion module, the defect analysis module, the defect detection module and the positioning clamping module are arranged above the vibration isolation module, and the vibration isolation module is used for keeping stability of positional relation between the rest modules and the testing sample piece in the testing process, and is particularly not influenced by environmental vibration.

The invention also provides a defect detection method of the optical element defect detection system, which comprises the following steps:

the method comprises the following steps: performing sample scanning test, namely performing two-dimensional scanning on a test sample piece by using a laser beam to form a defect statistical table and a defect distribution schematic diagram;

step two: acquiring detection data, and performing high-magnification microscopic imaging and size judgment on the defects according to all the defects or selected defect position coordinates obtained in the first step;

step three: analyzing the defect type, and performing classification statistics on the defects through a defect background removal algorithm and a defect characteristic identification contrast classification flow;

step four: and C, evaluating the defect characteristics, namely analyzing and evaluating the defects classified in the step three according to the defect judgment conditions and requirements.

Preferably, before the sample scanning test, the posture of the sample piece needs to be adjusted, specifically: and adjusting the pitching inclination state of the sample piece according to the automatic focusing definition under the high-power objective lens, wherein the high-power objective lens judges whether the posture of the sample piece forms a specified fixed included angle with the test light path by adopting a four-corner position judgment method and a four-edge and center position imaging judgment method.

Preferably, the sample scanning test adopts a composite test method combining laser scattering and high-power imaging.

Preferably, the defect type analysis specifically includes: removing background signals from defect scattering signals collected through the sample scanning test; extracting characteristic peak values through frequency conversion; judging the severity of the defect according to the height of the characteristic peak value; judging the shape and size of the defect according to the peak value integral area, and correspondingly determining the position of the defect according to the peak value position.

Preferably, the sample scanning test step specifically comprises: an incident laser beam is incident to the surface of a test sample piece at a given angle, the incident laser beam performs two-dimensional scanning operation in the transmission process, a detector performs real-time response to acquire a scattering signal, then the high-power objective lens images the positioned defect, a two-dimensional scattering image of the surface defect is formed through the two-dimensional scanning operation, the defect position is a bright point, and the defect position is a dark point.

Preferably, the defect scattering signals are divided into three types: background signal, background signal noise fluctuations and defect essence signal; the defect essential signal generates a peak value at the defect, and the defect is extracted by setting a defect signal threshold.

Preferably, the background signal is mainly generated by the ambient light intensity, the detector dark current and the sample surface roughness.

Preferably, the background signal noise is mainly generated by detector noise fluctuations, environmental noise fluctuations and sample surface roughness fluctuations.

Preferably, the range of testable apertures for defect detection of the test element includes 30mm x 30mm to 1500mm x500 mm.

Preferably, the defect detection of the test element can test and distinguish the defect with the size of not less than 0.3 mu m.

Preferably, the steps further comprise: starting equipment and software, initializing the system, setting system parameters, placing a sample to be measured, and setting measurement parameters.

Preferably, the system initialization setting specifically includes: the equipment automatically carries out system initialization on laser intensity, a polarized light transmission path, zero setting of a scanning system and the like.

Preferably, the system parameters set before the sample to be measured is placed include: and the evaluation mode, the software output format and the like select corresponding system file parameters such as test color distribution, contrast setting, laser light intensity setting, polarized light angle setting and the like according to the characteristics of the type of the test sample, the type of the detected defect, the appearance of the sample and the like, so that the test environment consistency of the same type of sample is ensured particularly under the condition of front and back comparison.

Preferably, the measurement parameters set after the sample to be measured is placed are specifically: detecting a scanning range, a testing depth, a testing type and the like, and inputting a sample name, a shape, a size and scanning parameters according to actual information: a scanning start point, a scanning end point, a scanning line number, and the like.

Preferably, the sample scanning test program tests the whole surface, converts the defect information in the optical signal into visual information for collection and storage, identifies, extracts and classifies the visual information, counts the detected defects through special software, and provides a judgment result and a conclusion according to the input judgment basis and outputs the judgment result and the conclusion.

Preferably, the detection system has the following advantages:

writing a defect identification algorithm, realizing an automatic statistical function, and carrying out classification statistics according to the appearances of different sizes.

And II, accepting and issuing a test result and a conclusion according to the judgment basis.

And thirdly, the background noise shielding technology based on laser irradiation can realize the defect detection of the optical mirror surface.

Fourthly, the cleanness and no pollution can be kept in the detection process.

Compared with the prior art, the invention has the following beneficial effects:

compared with the small-caliber sample piece processing and manual inspection processes in the prior art, the defect detection system and the defect detection method have the advantages that the defect appearance misjudgment and the defect positioning error possibly caused by some reasons through manual inspection are solved through the steps of detection data acquisition, defect type analysis, defect characteristic evaluation and the like, the defect positioning error occurrence rate is reduced, and the defect detection accuracy rate of the large-caliber optical element is further improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic diagram of a defect detection system for optical elements according to the present invention.

FIG. 2 is a flowchart illustrating a method for detecting defects of an optical device according to the present invention.

FIG. 3 is a schematic diagram of a defect scattering signal provided by the present invention.

FIG. 4 is a defect scan provided by the present invention.

FIG. 5 is a diagram illustrating the results of laser scattering defect detection provided by the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention discloses a system for detecting the defects of an optical element in a first aspect.

Referring to the specification and the attached fig. 1, a schematic diagram of an optical element defect detection system is shown, which comprises the following modules:

the positioning and clamping module 105 is used for positioning and clamping a test sample and automatically adjusting the posture of the test sample;

the defect detection module 104 is used for detecting and recording the defects of the test sample piece through laser scattering scanning and high-power objective imaging;

the defect analysis module 103 is used for carrying out classification statistics on the defects through a defect background removal algorithm and a defect characteristic identification contrast classification flow;

the scanning motion module 102 is used for carrying a defect detection module 104 and testing and splicing the whole surface of the large-caliber test sample; splicing means that a plurality of small area tests in the test process of the large-caliber sample piece are spliced through a splicing algorithm to realize the display of the large-caliber full range;

and the electrical control module 101 is used for controlling the motion of the scanning motion module 102 and the test of the test sample.

In one embodiment, a laser emission detection system and a high power microscope are disposed in the defect detection module 104.

In one embodiment, the high power microscope is horizontally positioned adjacent to the laser emission testing system.

In one embodiment, a laser emission detection system includes a laser emitter, a laser power adjustment device, a beam shaping module, a light polarization control module, a beam focusing module, a laser scatter detection module, a laser scatter collection module, and a reflected light control module.

In one embodiment, the electrical appliance control module is further configured to perform feedback processing on the sensor signal, and the like, so as to ensure that the device operates normally according to the instruction.

In one embodiment, a bed support module 107 is included, located at the bottom of the overall system, for supporting the rest of the system and for placement of test samples.

In one embodiment, the vibration isolation module 106 is located above the bed supporting module 107, the electrical control module 101, the scanning motion module 102, the defect analysis module 103, the defect detection module 104 and the positioning and clamping module 105 are located above the vibration isolation module 106, and the vibration isolation module 106 is used for maintaining the stability of the positional relationship between the rest modules and the test sample during the test process, and is particularly not affected by environmental vibration.

In one embodiment, optical mirror defect detection may be achieved based on background noise masking techniques of laser irradiation.

In one embodiment, the defect detection process may be kept clean and free of contamination.

The second aspect of the embodiment of the invention also discloses a defect detection method of the optical element defect detection system.

Referring to the description and the attached fig. 2, a working flow chart of a defect detection method for an optical element includes the following steps:

the method comprises the following steps: performing sample scanning test, namely performing two-dimensional scanning on a test sample piece by using a laser beam to form a defect statistical table and a defect distribution schematic diagram;

step two: acquiring detection data, and performing high-magnification microscopic imaging and size judgment on the defects according to all the defects or selected defect position coordinates obtained in the first step;

step three: analyzing the defect type, and performing classification statistics on the defects through a defect background removal algorithm and a defect characteristic identification contrast classification flow;

step four: and C, evaluating the defect characteristics, namely analyzing and evaluating the defects classified in the step three according to the defect judgment conditions and requirements.

In one embodiment, the sample attitude adjustment is required before the sample scan test, specifically: and adjusting the pitching inclination state of the sample piece according to the automatic focusing definition under the high-power objective lens, and judging whether the posture of the sample piece forms a specified fixed included angle with the test light path or not by adopting a four-corner position judgment method and a four-edge and center position imaging judgment method through the high-power objective lens.

In one embodiment, the fixed included angle generally ranges from 60 to 80.

In one embodiment, the sample scan test employs a composite test method of laser light scattering combined with high power imaging.

In one embodiment, the defect type analysis specifically includes: removing background signals of defect scattering signals collected through sample scanning test; extracting characteristic peak values through frequency conversion; judging the severity of the defect according to the height of the characteristic peak value; judging the shape and size of the defect according to the peak value integral area, and correspondingly determining the position of the defect according to the peak value position.

In one embodiment, the sample scan testing step specifically comprises: the incident laser beam is incident to the surface of the test sample piece at a given angle, the incident laser beam performs two-dimensional scanning operation in the transmission process, the detector performs real-time response to acquire a scattering signal, then the high-power objective lens images the positioned defect, and a two-dimensional scattering image of the surface defect is formed through the two-dimensional scanning operation, wherein the defect is a bright point, and the defect is not a dark point.

In one embodiment, the defect scatter signals are divided into three categories: background signal, background signal noise fluctuations and defect essence signal; the defect essential signal generates a peak value at the defect, and the defect is extracted by setting a defect signal threshold.

In one embodiment, the background signal is mainly generated by ambient light intensity, detector dark current, and sample surface roughness.

In one embodiment, the background signal noise is generated primarily due to detector noise fluctuations, environmental noise fluctuations, and sample surface roughness fluctuations.

In one embodiment, the range of testable apertures for defect detection on test elements includes 30mm-1500mm 500mm and can be tested to resolve defects on a scale of no less than 0.3 μm.

In one embodiment, further comprising: starting equipment and software, initializing the system, setting system parameters, placing a sample to be measured, and setting measurement parameters.

In one embodiment, the system initialization setting is specifically: the equipment automatically carries out system initialization on laser intensity, a polarized light transmission path, zero setting of a scanning system and the like.

In one embodiment, the system parameters set prior to placing the sample under test include: and the evaluation mode, the software output format and the like select corresponding system file parameters such as test color distribution, contrast setting, laser light intensity setting, polarized light angle setting and the like according to the characteristics of the type of the test sample, the type of the detected defect, the appearance of the sample and the like, so that the test environment consistency of the same type of sample is ensured particularly under the condition of front and back comparison.

In one embodiment, the measurement parameters set after the sample to be measured is specifically: detecting a scanning range, a testing depth, a testing type and the like, and inputting a sample name, a shape, a size and scanning parameters according to actual information: a scanning start point, a scanning end point, a scanning line number, and the like.

In one embodiment, the sample scan test procedure is used for testing the whole surface, converting the defect information in the optical signal into visual information for collection and storage, identifying through special software, extracting and classifying, counting the detected defects, and providing and outputting the judgment result and conclusion according to the input judgment basis.

The following are specific steps performed to test the defects of the 400mm × 400mm × 40mm fused silica sample by using the method for detecting defects of an optical element provided in the second aspect of the present embodiment:

firstly, a power switch of the equipment is started, special test software of the equipment is started, and the equipment automatically carries out system initialization on laser intensity, a polarized light transmission path, zero setting of a scanning system and the like;

and then, aiming at the characteristics of the type of the tested sample piece, the type of the tested defect, the appearance of the sample and the like, selecting corresponding system file parameters, such as testing color distribution R:149, G:200, B:190 and contrast setting: 55% and laser intensity setting: 39 percent, 45 degrees of polarized light angle and the like, and ensures that the test environment of the same type of sample is consistent especially under the condition of front-back comparison.

And then placing the sample piece to a specified position according to requirements, positioning and clamping, starting a sample piece posture adjusting function, adjusting the pitching inclination state of the sample piece according to the automatic focusing definition under the high-power objective lens, judging by adopting the positions of four corners of the element, and judging whether the posture of the sample piece forms a certain fixed included angle with a test light path or not through imaging of the positions of four sides and the center of the element. (the included angle is generally controlled in the range of 60-80 degrees, and improper angle selection may affect the detection accuracy of some shallow scratches).

Then the sample name is input according to the actual information: large-caliber fused quartz sample piece, shape: rectangle, size: 400mm × 400mm and scan parameters: a start point of scanning (100mm, 50mm), an end point of scanning (500mm, 450mm), a number of scanning lines 46, and the like.

Executing a sample scanning program, from a scanning starting point to a scanning end point, generating a defect statistical table and a defect distribution schematic diagram, carrying out high-odds ratio microscopic imaging and size judgment on defects according to all defects or selected defect position coordinates, filling the shape information into the defect statistical table, classifying defects according to defect conditions, such as scratch defects, carrying out statistics on a plurality of steps of which the width information is generally designed to be less than or equal to 1 mu m, 1 mu m to 3 mu m, 3 mu m to 6 mu m, 6 mu m to 10 mu m, 11 mu m to 20 mu m, 21 mu m to 30 mu m, 31 mu m to 40 mu m, larger than 40 mu m and the like, and respectively obtaining corresponding defect width and area information. And inputting judgment conditions and requirements by the human-computer interaction interface, and automatically issuing detailed test reports by the equipment and judging whether the requirements are met.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.