CN104406988A - Method for detecting defects inside glass - Google Patents

Method for detecting defects inside glass Download PDF

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Publication number
CN104406988A
CN104406988A CN201410659995.2A CN201410659995A CN104406988A CN 104406988 A CN104406988 A CN 104406988A CN 201410659995 A CN201410659995 A CN 201410659995A CN 104406988 A CN104406988 A CN 104406988A
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China
Prior art keywords
glass
defect
tested
lamella
image
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Pending
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CN201410659995.2A
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Inventor
周滨
汪凯巍
王晨
白剑
何帆
张赛
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Zhejiang University ZJU
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Zhejiang University ZJU
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Priority to CN201410659995.2A priority Critical patent/CN104406988A/en
Publication of CN104406988A publication Critical patent/CN104406988A/en
Pending legal-status Critical Current

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Abstract

The invention discloses a method for detecting defects inside glass. The method comprises the following steps: in a dark environment, irradiating the side surface of glass to be detected by using a linearly-structured light source, wherein the defects inside the glass such as impurities and cracks can scatter a part of light, shooting from the front surface of the glass to be detected by using a high-resolution CCD (charge coupled device) camera, recording a series of images with defect information, moving the glass to a next position, shooting again, and finally obtaining defect images of all irradiated positions of the side surface of the glass to be detected. The visual field of the high-resolution CCD camera is limited, so that firstly, images in a certain layer are two-dimensionally stitched to obtain the defect images of the layer, secondly, two-dimensional coordinates and the layer number of the defects are recorded, and finally, the defect images of all layers are three-dimensionally reconstructed to obtain three-dimensional images of the defects inside the whole glass. The detection method is simple and high in detection accuracy, can accurately detect positions of the defects inside the glass such as the impurities and the cracks.

Description

A kind of detection method of inside glass defect
Technical field
The present invention relates to a kind of detection method of inside glass defect, be applicable to glass, optical element blank, other transparent materials as the detection of the inherent vice such as plastics, crystal.
Background technology
Glass in process of production, due to the reason such as material purity, production technology, can introduce impurity, bubble in the inside of glass, or even the defect such as slight crack, and these defects can increase the fragility of glass, and reduce its mechanical property.When being used for when being with defective glass producing the optical instrument such as optical lens, due to produce parasitic light and energy absorption uneven, image quality can be reduced, even cause the damage of optical system.Therefore, in Improving Glass Manufacturing Processes and quality control, how to check and identify that the defect of inside glass becomes problem demanding prompt solution.At present, many glass production producers are also using this traditional method of inspection of visual method, namely under the test condition of regulation, utilize bore hole to carry out defect inspection to glass, this method not only wastes time and energy, and precision is very low, efficiency is not high, completely with the subjective judgement of reviewer.Some producer utilizes microscope to check defect, although this method precision is higher than visual method, visual field is very little, be unfavorable for the detection of Large diameter glass, and workload is very large.
Therefore, need to develop a kind of detection method that automatically can detect inside glass defect, the type of defect, positional information can be detected, and very high efficiency and precision will be had, thus well control the quality of glass.
Summary of the invention
The present invention is directed to that prior art measuring accuracy is not high, efficiency is lower and the deficiency such as automatically can not to detect, provide a kind of detection method of inside glass defect, from the side glass is thrown light on by line structure light source, obtain the defect information of each lamella, finally carry out three-dimensional reconstruction, obtain the three-dimensional coordinate of whole inside glass defect.
The object of the invention is to be achieved through the following technical solutions: a kind of detection method of inside glass defect, comprises the following steps:
(1) scanning shoot inside glass defect image, specifically comprises following sub-step:
(1.1) under details in a play not acted out on stage, but told through dialogues environment, utilize line structure light source 1 to aim at the high order end of tested glass 3 side, the visual field of CCD camera 4 is aimed at the most upper left side in tested glass 3 front; Utilize CCD camera 4 to take from the front of tested glass 3, mobile tested glass 3 makes CCD camera 4 take tested glass 3 according to snake scan mode, and what obtain the first lamella a series ofly has a sub-aperture image of overlapping region with defect information;
(1.2) tested glass 3 is moved a step-length, make line structure light source 1 aim at the second lamella of tested glass 3 side; Described step-length equals the live width of line structure light source 1, and CCD camera 4 moves identical step-length to equidirectional, repeats the snake scan process of step 1.1, obtains the defect image of tested glass 3 second lamella;
(1.3) step 1.2 is repeated until complete the scanning of the tested whole side of glass 3;
(2) three-dimensional reconstruction of inside glass defect, specifically comprises following sub-step:
(2.1) by the sub-aperture image of a certain lamella according to the characteristic information of adjacent sub-aperture image overlapping region, by least square method carry out two dimension splicing, obtain the glass defect image of this lamella, the two-dimensional coordinate of recording defect and affiliated lamella sequence number;
(2.2) three-dimensional reconstruction is carried out to the glass defect image of all lamellas, obtain the inherent vice 3-D view of tested glass 3, thus complete the detection to tested glass 3 inherent vice.
Further, the live width of described line structure light source 1 is less than 50 μm.
Further, the depth of field of described CCD camera 4 camera lens is greater than the live width of line structure light source 1.
Further, the inherent vice 3-D view obtaining tested glass 3 described in is specially: for independently defect point, provide location coordinate information, for slight crack, provide position and the length information of slight crack.
Beneficial effect of the present invention is as follows:
1, automatically detecting: the present invention only need set the moving step length of three-D displacement platform in testing process, utilize CCD camera to take image, the automatic detection to whole glass can be completed, a large amount of quality time be economized for producing procedure section.
2, precision is high: the present invention can detect the defect of tens microns of sizes, substantially meets the inside glass defects detection accuracy requirement in general production run.
3, applied range: be applicable to glass, optical element blank, other transparent materials as the detection of the inherent vice such as plastics, crystal, and the detection of heavy caliber inside glass defect can be applied to.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of the detection method of a kind of inside glass defect provided by the invention device used;
Fig. 2 is CCD camera scanning shoot path;
In figure: 1 is line structure light source, 2 is the three-D displacement platform of placing glass, and 3 is tested glass, and 4 is CCD camera, and 5 is the one dimension displacement platform of placing CCD camera, and 6 is computing machine.
Embodiment
In order to technical scheme of the present invention is described better, be described in further detail below in conjunction with accompanying drawing.
Fig. 1 is the schematic diagram of the detection method of a kind of inside glass defect provided by the invention device used, pick-up unit comprises line structure light source 1, the three-D displacement platform 2 of placing glass, high-resolution CCD camera 4, the one dimension displacement platform 5 of placing CCD camera and computing machine 6, tested glass 3 is placed on three-D displacement platform 2, can move along xyz tri-directions, CCD camera 4 is placed on one dimension displacement platform 5, can move in the x-direction, take from the front vertical of tested glass 3, line structure light source 1 position is fixed, throw light on from the incidence of tested glass 3 lateral vertical.
The detection method of a kind of inside glass defect of the present invention, comprises the following steps:
Step 1: scanning shoot inside glass defect image, be specially: under details in a play not acted out on stage, but told through dialogues environment, adjust three-D displacement platform 2 in the x-direction, line structure light source 1 is made to aim at the high order end of tested glass 3 side, i.e. the first lamella of tested glass 3, along y, z direction adjustment three-D displacement platform 2, the visual field of CCD camera 4 is made to aim at the most upper left side in tested glass 3 front, the focal plane of adjustment CCD camera 4, make the front of its tested glass 3 of focusing, utilize computing machine 6 to control CCD camera 4 and take image, at y, the moving step length of z direction setting three-D displacement platform 2, described moving step length is less than the visual field of CCD camera 4, then three-D displacement platform 2 is driven to carry out snake scan by the mode of Fig. 2, shooting obtains a series of sub-aperture images with defect information of the first lamella, then the live width of line structure light source 1 is equaled at the moving step length of x direction setting three-D displacement platform 2, namely 50 μm, the moving step length simultaneously setting one dimension displacement platform 5 equals the live width of line structure light source 1, drive two displacement platforms mobile step-length in the x-direction simultaneously, repeat above-mentioned snake scan process again, obtain the defect image of tested glass 3 second lamella.Repeat said process, until the side of whole tested glass 3 is all illuminated.
Step 2: the three-dimensional reconstruction of inside glass defect, be specially: under details in a play not acted out on stage, but told through dialogues environment, when there is the defect such as impure point, slight crack in tested glass 3 inside, the light that these scatterers meeting scattering is incident from the side, can obtain defect image clearly by high resolution CCD camera 4 shooting of glass front; When tested inside glass does not have defect, because do not have light to penetrate from the front of glass, therefore CCD camera 4 takes the image obtained is details in a play not acted out on stage, but told through dialogues.Owing to using line structure light source 1 to throw light on, so the defect that the image that shooting obtains comprises is point defect, namely defect image can be divided into the image and zero defect image that comprise point defect.
When carrying out two-dimentional sub-aperture stitching to the image of a certain lamella, first extract the overlapping region of right side (removing rightmost one arranges) and downside (the removing a line bottom) of often opening sub-aperture image, the size of overlapping region generally gets 1/4th of sub-aperture image area, binary conversion treatment is carried out to overlapping region, image after process is carried out to the mark of connected region, namely each connected region represents a unique point, if do not have connected region, then this image does not have unique point.Then by the overlapping region containing unique point with do not classify containing the overlapping region of unique point, and record numbering, the position (right side or downside) in the picture of image belonging to the overlapping region containing unique point, and the position of a unique point.Then with the unique point of overlapping region for first template splices the image comprising defect, namely choose the suitable template of a block size at characteristic point position place, utilize least square method carry out the degree of correlation coupling splicing.
If A 1(m 0+ i, n 0+ j) be template A 1be positioned at (m 0+ i, n 0+ j) gray-scale value of place's pixel; B 1(m 1+ i, n 1+ j) be overlapping region B 1be positioned at (m 1+ i, n 1+ j) gray-scale value of place's pixel, usually get the quadratic sum of their gray scale differences as judgment criteria:
D ( m 1 , n 1 ) = Σ i = 1 M - 1 Σ j = 1 N - 1 [ A 1 ( m 0 + i , n 0 + j ) - B 1 ( m 1 + i , n 1 + j ) ] 2 - - - ( 1 )
Launch, can obtain:
D ( m 1 , n 1 ) = Σ i = 1 M - 1 Σ j = 1 N - 1 [ A 1 ( m 0 + i , n 0 + j ) ] 2 - 2 Σ i = 1 M - 1 Σ j = 1 N - 1 B 1 ( m 1 + i , n 1 + j ) × A 1 ( m 0 + i , n 0 + j ) + Σ i = 1 M - 1 Σ j = 1 N - 1 [ B 1 ( m 1 + i , n 1 + j ) ] 2 - - - ( 2 )
The related coefficient of template matches will can be obtained after formula (2) normalization
ϵ ( m 1 , n 1 ) = Σ i = 1 M - 1 Σ j = 1 N - 1 B 1 ( m 1 + i , n 1 + j ) × A 1 ( M 0 + i , N 0 + j ) Σ i = 1 M - 1 Σ j = 1 N - 1 [ A 1 ( m 0 + i , n 0 + j ) ] 2 Σ i = 1 M - 1 Σ j = 1 N - 1 [ B 1 ( m 1 + i , n 1 + j ) ] 2 - - - ( 3 )
In above formula, M, N are respectively template A 1length and width, (m 0, n 0), (m 1, n 1) be respectively template A 1, overlapping region B 1the coordinate of top left corner pixel point, ε (m 1, n 1) be m 1and n 1function.
Usual ε (m 1, n 1) value larger, module matching degree is higher, works as A 1and B 1gray-scale value complete equal time, ε (m 1, n 1) value be 1.In actual splicing, the position (m of movable platen in figure to be spliced 1, n 1) determine optimal match point.
In order to reduce the error of splicing, with the first splicing that two width image distances are nearer, after distant, be spliced into principle.After the first round spliced, remaining image overlapping region containing unique point, can only not determined the relative position of two width images, they is stitched together by the displacement of three-D displacement platform 2.After two-wheeled splicing, just can obtain the panorama sketch of a certain lamella glass front.Then by image procossing, the two-dimensional coordinate of all defect point and the sequence number of affiliated lamella on panorama sketch is recorded.
Carry out three-dimensional reconstruction to all slice image obtained, the tool box namely utilizing MATLAB software to carry carries out said three-dimensional body reconstruction to the section obtained, and obtains the 3-D view of whole inside glass defect.For independently defect point, provide location coordinate information, for slight crack, due to line structure light source 1, be shown as a point on 2d, pass through three-dimensional reconstruction, the information of depth direction is reduced, obtain the profile of slight crack, provide position and the length information of slight crack, thus complete the detection to whole inside glass defect.

Claims (4)

1. a detection method for inside glass defect, is characterized in that, comprises the following steps:
(1) scanning shoot inside glass defect image, specifically comprises following sub-step:
(1.1) under details in a play not acted out on stage, but told through dialogues environment, utilize line structure light source 1 to aim at the high order end of tested glass 3 side, the visual field of CCD camera 4 is aimed at the most upper left side in tested glass 3 front; Utilize CCD camera 4 to take from the front of tested glass 3, mobile tested glass 3 makes CCD camera 4 take tested glass 3 according to snake scan mode, and what obtain the first lamella a series ofly has a sub-aperture image of overlapping region with defect information;
(1.2) tested glass 3 is moved a step-length, make line structure light source 1 aim at the second lamella of tested glass 3 side; Described step-length equals the live width of line structure light source 1, and CCD camera 4 moves identical step-length to equidirectional, repeats the snake scan process of step 1.1, obtains the defect image of tested glass 3 second lamella;
(1.3) step 1.2 is repeated until complete the scanning of the tested whole side of glass 3;
(2) three-dimensional reconstruction of inside glass defect, specifically comprises following sub-step:
(2.1) by the sub-aperture image of a certain lamella according to the characteristic information of adjacent sub-aperture image overlapping region, by least square method carry out two dimension splicing, obtain the glass defect image of this lamella, the two-dimensional coordinate of recording defect and affiliated lamella sequence number;
(2.2) three-dimensional reconstruction is carried out to the glass defect image of all lamellas, obtain the inherent vice 3-D view of tested glass 3, thus complete the detection to tested glass 3 inherent vice.
2. the detection method of a kind of inside glass defect according to claim 1, it is characterized in that, the live width of described line structure light source 1 is less than 50 μm.
3. the detection method of a kind of inside glass defect according to claim 1, it is characterized in that, the depth of field of described CCD camera 4 camera lens is greater than the live width of line structure light source 1.
4. the detection method of a kind of inside glass defect according to claim 1, it is characterized in that, in described step 2.2, the described inherent vice 3-D view obtaining tested glass 3 is specially: for independently defect point, provide location coordinate information, for slight crack, provide position and the length information of slight crack.
CN201410659995.2A 2014-11-18 2014-11-18 Method for detecting defects inside glass Pending CN104406988A (en)

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Cited By (10)

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CN105894036A (en) * 2016-04-19 2016-08-24 武汉大学 Image feature template matching method being applied to detection of mobile phone screen defects
WO2016192534A1 (en) * 2015-06-03 2016-12-08 Saint-Gobain Glass France Optical device for detecting an internal flaw of a transparent substrate and method for the same
CN107621469A (en) * 2016-07-15 2018-01-23 克朗斯股份公司 Container inspection arrangement with multiple lighting devices
TWI640748B (en) * 2017-10-26 2018-11-11 頂瑞機械股份有限公司 Method for examining a glass
CN109187575A (en) * 2018-08-16 2019-01-11 中国科学院上海光学精密机械研究所 The internal defect detection device and detection method of heavy caliber birefringece crystal
CN111366592A (en) * 2020-04-15 2020-07-03 西北核技术研究院 Automatic fragment detection system based on industrial photogrammetry
CN113469472A (en) * 2021-09-06 2021-10-01 中导光电设备股份有限公司 Multi-microscope fixed-point photographing path optimization method
CN114897906A (en) * 2022-07-14 2022-08-12 南通华烨塑料工业有限公司 Modified plastic appearance defect control method based on computer vision
WO2022262133A1 (en) * 2021-06-16 2022-12-22 美晟通科技(苏州)有限公司 Method and device for detecting position of stain on transparent medium
CN117309903A (en) * 2023-10-10 2023-12-29 青岛峻海物联科技有限公司 Method and device for positioning defects in tunnel

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Cited By (12)

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Publication number Priority date Publication date Assignee Title
WO2016192534A1 (en) * 2015-06-03 2016-12-08 Saint-Gobain Glass France Optical device for detecting an internal flaw of a transparent substrate and method for the same
US10429317B2 (en) 2015-06-03 2019-10-01 Saint-Gobain Glass France Optical device for detecting an internal flaw of a transparent substrate and method for the same
CN105894036A (en) * 2016-04-19 2016-08-24 武汉大学 Image feature template matching method being applied to detection of mobile phone screen defects
CN105894036B (en) * 2016-04-19 2019-04-09 武汉大学 A kind of characteristics of image template matching method applied to mobile phone screen defects detection
CN107621469A (en) * 2016-07-15 2018-01-23 克朗斯股份公司 Container inspection arrangement with multiple lighting devices
TWI640748B (en) * 2017-10-26 2018-11-11 頂瑞機械股份有限公司 Method for examining a glass
CN109187575A (en) * 2018-08-16 2019-01-11 中国科学院上海光学精密机械研究所 The internal defect detection device and detection method of heavy caliber birefringece crystal
CN111366592A (en) * 2020-04-15 2020-07-03 西北核技术研究院 Automatic fragment detection system based on industrial photogrammetry
WO2022262133A1 (en) * 2021-06-16 2022-12-22 美晟通科技(苏州)有限公司 Method and device for detecting position of stain on transparent medium
CN113469472A (en) * 2021-09-06 2021-10-01 中导光电设备股份有限公司 Multi-microscope fixed-point photographing path optimization method
CN114897906A (en) * 2022-07-14 2022-08-12 南通华烨塑料工业有限公司 Modified plastic appearance defect control method based on computer vision
CN117309903A (en) * 2023-10-10 2023-12-29 青岛峻海物联科技有限公司 Method and device for positioning defects in tunnel

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