CN112326665B - Defect detection system based on space step-by-step frequency shift illumination - Google Patents
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Abstract
The invention discloses a defect detection system based on space step-by-step frequency shift illumination, which comprises a light source, a microscope objective, a tube lens, an image detector, a control module and a data processing module, wherein the light source comprises a vertical illumination light source and an inclined illumination unit. The emergent light of the vertical illumination light source and each inclined illumination unit can irradiate the observed sample to excite a scattered field, the scattered field is collected by a microscope objective, and then is shaped by a tube mirror to be incident to an image detector, and the scattered field is converted into a far-field intensity graph by a data processing module. The control module controls the lighting of each light source according to the time sequence, and the image detector acquires the observed sample scattering field signal under the illumination of each light source. The data processing module finally realizes detection imaging of complex defect feature contour information and detail feature information on the surface of the observed sample under the condition of transmission illumination or reflection illumination through reconstructing the space spectrum information of the observed sample.
Description
Technical Field
The invention relates to a product surface defect detection device, and belongs to the field of surface defect detection.
Background
The defect detection on the surface of the product is one of important means for realizing the quality control of the product, improving the production process and optimizing the performance of the product. Manual detection is a traditional method for detecting surface defects of products, but with the development and progress of society, the traditional detection method cannot meet the requirements of detection speed, detection accuracy and the like. With the development of industrial automation, the defect detection technology based on machine vision is rapidly developed by virtue of the advantages of non-contact, no damage, safety, reliability, wide spectral response range, high production efficiency and the like. The patent document with publication number CN105973912A discloses a dermis surface defect detection device based on linear array light source illumination and linear array industrial camera detection; patent document CN104897693a proposes a glass surface defect enhancement detection device, which realizes amplified imaging of a surface defect of an observed sample through oblique illumination in a single direction, but is limited by a numerical aperture NA (usually a low-power large-field low-NA microscope objective) of an imaging receiving objective, and the spatial spectrum information of a sample which can be received by single illumination imaging is limited, so that defect characteristics stepped along other directions are lost. The patent document with publication number of CN102023164A provides a detection device for low-angle annular light source dark field illumination, and the illumination imaging mode solves the defect characteristic missing problem of unidirectional illumination, but can not give all detail information of an observed sample with larger size span through spectrum reconstruction due to aliasing of spectrum information, so that the problems of missed detection and false detection exist.
Patent documents with publication numbers of CN105225202A, CN104181686A and CN106199941A propose an FPM imaging method, and the method improves the space bandwidth product SBP (Space Bandwidth Product) of the whole imaging system in a sample space spectrum reconstruction mode, so as to further realize the amplification and reconstruction of sample space spectrum information. However, the methods proposed in the related patent documents are all transmissive illumination, and are not applicable to microscopic observation of the surface of a non-transparent sample. Meanwhile, when the LED lighting unit is far from the center, the divergence angle of the incident light is large, and the accuracy of sub-aperture spectrum information acquired by fourier transform may be lowered.
A defect detection device capable of realizing rapid stepwise reflection illumination and improving the spatial bandwidth product of an imaging system through accurate spectrum reconstruction is not available at present.
Disclosure of Invention
The invention aims to provide a defect detection system based on space step-by-step frequency shift illumination, which acquires detailed characteristic information of complex defects on the surface of an observed sample through reconstruction of sub-aperture spectrum information.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: the defect detection system based on space step-by-step frequency shift illumination comprises a light source, a microscope objective, a tube mirror, an image detector, a control module and a data processing module, wherein the light source comprises a vertical illumination light source and an inclined illumination unit; the emergent light of the vertical illumination light source and each inclined illumination unit can irradiate the observed sample to excite a scattering field; the scattered field can be collected by a microscope objective, and then is shaped by the microscope and is incident to an image detector, and the image detector collects scattered field signals; the control module can control the image detector to collect the scattered field signal of the observed sample under the illumination condition of each light source according to the time sequence, convert the scattered field signal into an electrical signal and send the electrical signal to the data processing module, and can lighten the next light source after the collection of the scattered field signal under the illumination condition of one light source is completed; the control module can control the data processing module to convert the electrical signals from the image detector into far-field intensity patterns, acquire sub-aperture spectrum information of each far-field intensity pattern and perform spectrum splicing reconstruction; the adjacent sub-aperture frequency spectrum information corresponding to the far field intensity map formed under the irradiation of the vertical illumination light source and each inclined illumination unit are overlapped with each other, so that the data processing module can acquire wide-band spatial frequency spectrum information convergence solution of the observed sample when performing spatial frequency spectrum reconstruction according to a frequency spectrum splicing reconstruction method, and a reconstructed image of the observed sample is obtained.
Further, the vertical illumination light source, the inclined illumination unit, the microscope objective and the image detector are all positioned on the same side of the observed sample; alternatively, the vertical illumination source, the oblique illumination unit are located on one side of the observed sample, and the microscope objective and the image detector are located on the other side of the observed sample.
Further, each inclined lighting unit is distributed in a concentric ring; alternatively, each inclined lighting unit is fixed on a spherical curved surface and distributed in a circular ring shape at different heights.
Further, the exit wavelengths of the tilted illumination units distributed on the same ring are the same.
Further, the light from the vertical illumination light source is vertically irradiated on the observed sample after passing through the optical lens, the beam splitter and the microscope objective lens.
Further, the invention also comprises a two-dimensional scanning micro-displacement platform, the sample platform is fixed on the two-dimensional scanning micro-displacement platform, and after the data processing module completes image reconstruction at one imaging position of the observed sample, the control module can control the two-dimensional scanning micro-displacement platform to move the observed sample on the sample platform to the next imaging position.
Further, the invention also comprises a display, wherein the display is connected with the data processing module.
Further, the invention also comprises a self-lock Jiao Mokuai, and the control module can control the self-lock Jiao Mokuai to perform real-time focus locking imaging on the surface of the observed sample.
Furthermore, the data processing module can splice reconstructed images of adjacent imaging positions of the observed sample surface.
Furthermore, the data processing module can intelligently identify and calibrate the defect characteristics of the obtained spliced image.
Compared with the prior art, the invention has the beneficial effects that: (1) By using the detection system provided by the invention, the outline information of the microstructure on the surface of the observed sample can be given, and the detail information in the image can be further given. (2) According to the invention, all detail information of the observed sample with larger size span can be given through spectrum reconstruction, and the problems of missed detection and false detection are effectively avoided. (3) When the defect detection method is used for detecting defects, the space bandwidth product of the imaging system can be improved by using accurate spectrum reconstruction not only by carrying out reflective illumination on transparent or non-transparent samples, but also by carrying out transmission illumination on transparent samples.
Drawings
FIG. 1 is a schematic diagram of a defect detection system based on spatially step-wise frequency-shifted illumination according to an embodiment of the present invention.
FIG. 2a is a schematic view of the inclined lighting unit of the present invention in concentric circular ring distribution; fig. 2b is a schematic view of spectral splice reconstruction when tilted lighting units are distributed in concentric circles as shown in fig. 2 a.
FIG. 3 is a timing diagram of the application of the vertical illumination source and three sets of annular oblique illumination units when the oblique illumination units are distributed in concentric circles as shown in FIG. 2a, where T represents time.
FIG. 4a is an ideal microstructure of a simulated design (concentric ring pair, line width 192nm, center-to-center spacing 960 nm); FIG. 4b is a reconstructed image of an observed sample obtained by spectral reconstruction when vertical illumination and 24-direction step-wise frequency-shift oblique illumination (from inside to outside, oblique illumination units on three sets of rings respectively corresponding to illumination oblique incidence angles of 25 DEG, 40 DEG and 65 DEG) are employed in the invention; FIG. 4c is a far field intensity plot of an observed sample (with an oblique incidence angle set at 65) using 360 annular low angle incidence illumination according to the prior art; fig. 4d is a far field intensity plot of an observed sample (with the oblique incidence set at 65 °) when prior art illumination is applied with a single direction low angle incidence.
FIG. 5 shows three imaging scanning modes of the two-dimensional scanning micro-displacement stage of the invention.
In FIG. 1, 101, a control module; 102. a vertical illumination source; 103. an optical lens; 104. a beam splitter; 105. a microobjective; 106. an observed sample; 107. a tube mirror; 108. an image detector; 109. a fixing device; 110. tilting the lighting unit; 111. a sample stage; 112. a two-dimensional scanning micro-displacement table; 113. a data processing module; 114. a display.
Detailed Description
The technical scheme of the invention is further described below with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1, the defect detection system based on space-step frequency-shift illumination of the present invention mainly includes a light source, a microscope objective 105, a tube mirror 107, an image detector 108, a control module 101, and a data processing module 113. Wherein the light sources include a vertical illumination light source 102 and an oblique illumination unit 110. The oblique illumination unit 110 may selectively use light sources such as an LED light source, an LD light source, and a fiber bundle output light source. Preferably, an optical collimator may be provided at the exit ports of the vertical illumination light source and each oblique illumination unit, so as to project the exit light into the imaging field of view of the optical microscope objective 105, thereby improving the directional collimation of the illumination field. Preferably, the output light of each oblique illumination unit 110 can directly irradiate the surface of the observed sample, or a light homogenizing element can be added at the output end of the light source, so that the surface of the observed sample is uniformly illuminated. To improve the imaging field of view of the overall system, the microscope objective 105 is preferably a low power objective, such as a 5X, 10X, 20X magnification microscope objective. The image detector 108 may be a CCD (charge coupled device), SCMOS (Scientific COMS, CMOS), or the like.
The light emitted from the vertical illumination light source 102 and each of the oblique illumination units 110 can be irradiated onto the sample to be observed to excite a scattering field, wherein the light emitted from the vertical illumination light source 102 is irradiated onto the sample to be observed vertically, and each of the oblique illumination units 110 is irradiated onto the sample to be observed at a certain inclination angle. The scattered field excited from the observed sample can be collected by the microscope objective 105, shaped by the tube mirror 107 and then incident on the image detector 108, and the image detector 108 collects the scattered field signal and converts the scattered field signal into an electrical signal to be sent to the data processing module 113. As an embodiment of the present invention, as shown in fig. 1, light from a vertical illumination light source 102 is vertically irradiated onto an observation sample through an optical lens 103, a beam splitter 104, and a microscope objective lens 105.
The control module 101 can control the image detector 108 to collect the scattered field signal of the observed sample under the illumination of each light source according to time sequence; after the image detector 108 completes the acquisition of the observed sample fringe field signal under the illumination condition of one light source, the control module 101 lights up the next light source, thereby realizing the space step-by-step frequency-shift illumination mode of the invention. Specifically, after the image detector 108 completes the acquisition of the scattered field signal of the observed sample under the irradiation of the vertical illumination light source 102, the control module 101 controls each of the oblique illumination units 110 to be sequentially lighted up according to a set time sequence, and the control module 101 controls the image detector 108 to acquire the scattered field signal of the observed sample under the irradiation of each of the oblique illumination units 110 in a time-sharing manner. The next oblique illumination unit is turned on after the image detector 108 completes acquisition of the fringe field signal under the illumination condition of the previous oblique illumination unit. The image detector 108 converts the observed sample scattered field signals irradiated by the vertical illumination light source 102 and each oblique illumination unit 110 into electrical signals and sends the electrical signals to the data processing module 113. The control module 101 controls the data processing module 113 to convert the electrical signals from the image detector 108 into a far field intensity pattern. The far field intensity pattern of the observed sample under the illumination condition of the last light source can be stored before the next light source is lighted, or can be stored simultaneously with or after the next light source is lighted. The invention can not only carry out reflective illumination imaging on transparent or non-transparent samples, but also carry out transmission illumination imaging on transparent samples, and can improve the spatial bandwidth product of an imaging system by using accurate spectrum reconstruction under two illumination imaging modes, thereby not only giving out the contour information of the microstructure on the surface of the observed sample, but also further giving out the detail information in the image.
In addition, the control module 101 can also control the data processing module 113 to acquire sub-aperture spectrum information of each far-field intensity map and perform spectrum splicing reconstruction. In the present invention, the adjacent sub-aperture spectrum information corresponding to the far field intensity map formed by the illumination of the vertical illumination light source 102 and each inclined illumination unit 110 are overlapped with each other, so that the data processing module 113 can obtain the convergence solution of the wide-frequency-band spatial spectrum information of the observed sample when performing spatial spectrum reconstruction according to the spectrum splicing reconstruction method, and obtain the reconstructed image of the observed sample. After the storage of far field intensity images under the illumination conditions of the vertical illumination light source 102 and all the oblique illumination units is completed, the data processing module 113 respectively acquires sub-aperture spectrum information corresponding to each far field intensity image formed under the illumination of each oblique illumination unit 110 by applying inverse fourier transform, and the morphological characteristics of the observed sample surface are reconstructed and restored according to a spectrum stitching reconstruction algorithm.
As shown in fig. 1, as an embodiment of the present invention, the vertical illumination source 102, the oblique illumination unit 110, the microscope objective 105, and the image detector 108 are all located on the same side of the observed sample, whereby reflective illumination imaging of transparent or non-transparent samples can be achieved. As another embodiment of the present invention, the vertical illumination light source 102, the oblique illumination unit 110 are located at one side of the observed sample, and the microscope objective 105 and the image detector 108 are located at the other side of the observed sample, whereby transmission illumination imaging of the transparent sample can be achieved.
As a preferred embodiment of the present invention, the oblique illumination units 110 are arranged in concentric rings, for example, as shown in fig. 2a, or concentric regular hexagons, concentric octagons, or concentric polygon rings (not shown). The oblique illumination units 110 are distributed in concentric rings, so that the control module 101 can light the oblique illumination units 110 layer by layer in the sequence from the inner ring to the outer ring or from the outer ring to the inner ring, thereby better realizing the time sequence control of the control module 101 on the illumination of each light source, the acquisition of a scattered field under the illumination of each light source and the time sequence control of the storage of a far field intensity map.
As another preferred embodiment of the present invention, the oblique illumination units 110 may not be distributed on the same plane, for example, may be fixed on a spherical surface and distributed in a circular ring shape (not shown in the figure) at different heights, and the normal line of the outgoing light field of each oblique illumination unit 110 points to the sphere center, and the sphere center coincides with the imaging field center of view of the microscope objective 105. As a preferred embodiment of the invention, the exit wavelengths of the oblique illumination units distributed on the same ring are identical.
As shown in fig. 1, each of the inclined illumination units 110 may be mounted on the fixture 109 as one embodiment of the present invention. The fixture 109 may be provided with concentric sets of annular supports, each inclined lighting unit 110 being fixed in a different annular support, and the spacing of adjacent rings may be equidistant or non-equidistant. Preferably, the inclination angle of the circular support can be adjusted, so that the inclination incidence angle of each inclined illumination unit 110 mounted on the support can be adjusted, the illumination intensity and uniformity of each inclined illumination unit 110 in the imaging field of view of the microscope objective 105 are improved, and the accuracy of sub-aperture spectrum information acquired by later image processing is further improved.
As a preferred embodiment, as shown in FIG. 1, the present invention may further comprise a two-dimensional scanning micro-displacement stage 112, and the sample stage 111 is fixed on the two-dimensional scanning micro-displacement stage 112. The range of the two-dimensional scanning micro-displacement stage 112 may be selected according to the sample size. After completing the reconstruction of the image at one imaging position of the observed sample, the control module 101 can control the two-dimensional scanning micro-displacement stage 112 to move the observed sample on the sample stage to the next imaging position, and can simultaneously map out the two-dimensional coordinate information corresponding to the next imaging position. By using the two-dimensional scanning micro-displacement table 112, the invention can give out all detail information of the observed sample with larger size span through spectrum reconstruction, thereby effectively avoiding the problems of missed detection and false detection.
As a preferred embodiment, as shown in FIG. 1, the present invention further includes a display 114, the display 114 being coupled to the data processing module 113.
As a preferred embodiment, the invention can further comprise a self-lock Jiao Mokuai, and the control module 101 can control the self-lock Jiao Mokuai to perform real-time focus locking imaging on the surface of the observed sample, so as to quickly adjust the Z-direction position of the microscope objective, and ensure that the focal plane of the microscope objective is located at the target level.
In a preferred embodiment, the data processing module 113 is also capable of stitching reconstructed images of adjacent imaging locations of a large-sized observed sample surface. In a preferred embodiment, the data processing module 113 can also perform intelligent identification and calibration of defect characteristics on the obtained spliced image when a large-size sample is observed.
In the embodiment shown in fig. 2a, the oblique illumination units 110 of the present invention are distributed in three concentric rings from inside to outside, corresponding to ring 1, ring 2 and ring 3 in sequence. The center of the imaging field of view of the microscope objective 105 is at the center of the three concentric rings. The arrangement of the three sets of concentric rings includes, but is not limited to, the following two: 1. the emergent light directions of the inclined illumination units 110 are all vertically downward and are in the same plane; 2. the exit directions of the tilted illumination units 110 in the same plane, but in three concentric circles, are all directed towards the center of the imaging field of view of the microscope objective 105.
As shown in fig. 2b, after the storage of far field intensity images at one imaging position of the observed sample under the vertical illumination light source 102 and all the oblique illumination units in the three groups of circles is completed, the data processing module 113 acquires sub-aperture spectrum information corresponding to each far field intensity pattern formed under the irradiation of each oblique illumination unit 110 by applying inverse fourier transform, and reconstructs and restores the morphological features of the observed sample surface according to the spectrum stitching reconstruction algorithm. Thereafter, the control module 101 controls the two-dimensional scanning micro-displacement stage 112 to move to the next imaging position of the observed sample.
Fig. 3 shows a timing diagram of the application of the vertical illumination sources and the oblique illumination units within each ring when the oblique illumination units are distributed in three concentric rings as shown in fig. 2 a. Time period t from left to right corresponding to the turn-on of the vertical illumination light source 0 Time period t during which each of the inclined illumination units in the ring 1 is sequentially lighted 1 Time period t during which each of the oblique illumination units in the ring 2 is sequentially turned on 2 And a time period t during which each of the oblique illumination units in the ring 3 is sequentially lighted 3 . Thus, the control module controls the vertical illumination sources, the oblique illumination units in the rings 1 to 3 to be sequentially lighted in order from the front to the back.
Fig. 4a shows an ideal dual pair ring structure (line width 192nm, pair center-to-center spacing 960 nm). If the step-by-step frequency-shift illumination imaging mode is adopted, the inclined incidence angles of the inclined illumination units in the three groups of circular rings from outside to inside are 65 degrees, 40 degrees and 25 degrees respectively, the numerical aperture angle of the microscope objective is 0.25, the third group of circular rings from inside to outside comprises 24 inclined illumination units distributed at equal intervals, and the corresponding reconstruction effect is shown in fig. 4 b. As can be seen by comparing with fig. 4a, the reconstruction result shown in fig. 4b shows that, with the detection system of the present invention, not only the contour information (circle) of the microstructure of the surface of the observed sample but also the detail information (double-line pair circular structure) in the image can be given. In comparison, the technical effect of the present invention cannot be achieved in the prior art, for example, an imaging scheme of patent document with publication number CN102023164a is adopted to apply 360 ° low-angle annular illumination to the sample, assuming that the oblique illumination angle is 65 °, the corresponding far-field imaging intensity diagram is shown in fig. 4c, and the detail features of the microstructure are missing; if the diagonal low-angle oblique illumination scheme in a single direction disclosed in the patent document with publication number CN104897693a is adopted, only the intensity information in the corresponding direction can be given, as shown in fig. 4d, not only the detailed information inside the microstructure is lost, but also the morphological features of the whole structure are lost.
Fig. 5 shows three scanning imaging modes of the two-dimensional scanning micro-displacement stage 112, the first scanning imaging mode being the Z-scan mode shown in fig. 5 a: after the system is locked, the control module 101 controls the displacement platform in the X direction to continuously move along the X direction according to the control time sequence, controls the scanning displacement platform in the Y direction to move by a certain step length after the line scanning in the X direction is completed, and then controls the scanning displacement platform in the X direction to reversely continuously scan and image. The process is repeated until the observation of the entire observed sample is completed. The second scanning imaging method is a comb scanning method shown in fig. 5b, and compared with the Z-scanning method shown in fig. 5a, after the line scanning is completed, the scanning displacement table in the X direction needs to be controlled to return to the start end, and then the scanning displacement table is moved a distance along the Y direction and the scanning of the next line is started. The third scanning imaging mode is the spiral scanning scheme shown in fig. 5c, after the edge searching of the observed sample is completed, the control module 101 controls the sample stage to move the center of the observed sample to be within the field of view of the imaging system, and then spiral scanning imaging is performed.
The preferred embodiments of the present invention have been described above in a non-limiting manner with reference to the accompanying drawings, but various modifications will fall within the scope of protection of the present invention without departing from the scope of the claims of the present invention. The electric scanning imaging mode using the two-dimensional scanning micro-displacement table can also be performed by adopting manual mechanical control; while the above embodiments illustrate illumination schemes with three sets of annularly distributed angled illumination units, other numbers of sets of annular structures may be employed to provide illumination, such as two sets, four sets, etc.; although only a concentric annular oblique illumination unit distribution structure is shown in the embodiment, an annular controllable oblique illumination unit array with a polygon such as a hexagon, an octagon, etc. can be adopted in practical application. Furthermore, in the simulation of the above embodiment, the oblique incidence angles of the three sets of concentric annular oblique illumination units are given, but in practical application, the adjustment may be performed according to requirements, for example, according to the overlapping ratio between sub-aperture spectrums. Meanwhile, in the simulation of the above embodiment, although the number of the three groups of concentric annular oblique illumination units is given, in practical application, the number of the concentric annular oblique illumination units can be adjusted according to parameters such as numerical aperture NA of the microscope objective, the size of the oblique incidence angle and the like.
Claims (10)
1. A defect detection system based on space stepwise frequency shift illumination is characterized in that: comprises a light source, a microscope objective (105), a tube mirror (107), an image detector (108), a control module (101) and a data processing module (113), wherein the light source comprises a vertical illumination light source (102) and an inclined illumination unit (110);
the outgoing light of the vertical illumination light source (102) and each inclined illumination unit (110) can irradiate the observed sample to excite a scattering field; the scattered field can be collected by a microscope objective (105), and then is shaped by a tube mirror (107) and is incident to an image detector (108), and the scattered field signal is collected by the image detector (108);
the control module (101) can control the image detector (108) to collect scattered field signals of an observed sample under the illumination condition of each light source according to time sequence, convert the scattered field signals into electrical signals and send the electrical signals to the data processing module (113), and can light the next light source after the collection of the scattered field signals under the illumination condition of one light source is completed; the control module (101) can control the data processing module (113) to convert the electrical signals from the image detector (108) into far-field intensity patterns and acquire sub-aperture spectrum information of each far-field intensity pattern for spectrum splicing and reconstruction;
the adjacent sub-aperture frequency spectrum information corresponding to the far field intensity map formed under the irradiation of the vertical illumination light source (102) and each inclined illumination unit (110) are overlapped with each other, so that the data processing module (113) can acquire the wide-frequency-band spatial frequency spectrum information convergence solution of the observed sample when performing spatial frequency spectrum reconstruction according to the frequency spectrum splicing reconstruction method, and a reconstructed image of the observed sample is obtained.
2. The defect detection system of claim 1, wherein: the vertical illumination light source (102), the inclined illumination unit (110), the microscope objective (105) and the image detector (108) are all positioned on the same side of the observed sample; alternatively, the vertical illumination source (102), the oblique illumination unit (110) are located on one side of the observed sample, and the microscope objective (105) and the image detector (108) are located on the other side of the observed sample.
3. The defect detection system of claim 1 or 2, wherein: each inclined lighting unit (110) is distributed in a concentric ring; alternatively, each of the inclined illumination units (110) is fixed on a spherically curved surface and distributed in a circular ring shape at different heights.
4. A defect detection system according to claim 3, wherein: the exit wavelengths of the tilted illumination units distributed on the same ring are the same.
5. The defect detection system of claim 1, 2 or 4, wherein: light from a vertical illumination light source (102) is vertically irradiated onto an observed sample after passing through an optical lens (103), a beam splitter (104) and a microscope objective (105).
6. The defect detection system of claim 1, 2 or 4, wherein: the two-dimensional scanning micro-displacement platform (112) is further included, the sample platform (111) is fixed on the two-dimensional scanning micro-displacement platform (112), and after the data processing module completes image reconstruction at one imaging position of the observed sample, the control module (101) can control the two-dimensional scanning micro-displacement platform (112) to move the observed sample on the sample platform to the next imaging position.
7. The defect detection system of claim 1, 2 or 4, wherein: the display (114) is also included, and the display (114) is connected with the data processing module (113).
8. The defect detection system of claim 1, 2 or 4, wherein: the system also comprises a self-lock Jiao Mokuai, and the control module can control the self-lock Jiao Mokuai to perform real-time focus locking imaging on the surface of the observed sample.
9. The defect detection system of claim 1, 2 or 4, wherein: the data processing module (113) is capable of stitching reconstructed images of adjacent imaging locations of the observed sample surface.
10. The defect detection system of claim 9, wherein: the data processing module (113) can intelligently identify and calibrate defect characteristics of the obtained spliced image.
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| CN202011039692.2A CN112326665B (en) | 2020-09-28 | 2020-09-28 | Defect detection system based on space step-by-step frequency shift illumination |
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