JP2005337856A - Visual inspection apparatus and visual inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a visual inspection apparatus which can quickly and precisely inspect unevenness of the surface of an object to be inspected. <P>SOLUTION: The apparatus includes: two projection devices 15a and 15b each for irradiating the surface of the object 12 to be inspected with a line-like convergent light flux from a different direction; an imaging device 13 for imaging two laser light cutting lines formed on the surface of the object 12 to be inspected by the line-like laser lights 1a and 1b from the projection devices 15a and 15b, respectively; and a processor 17 for calculating the height or the depth of the unevenness formed on the surface of the object 12 to be inspected, on the basis of the image data outputted from the imaging device 13 in which the two laser light cutting lines are imaged. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus and method for inspecting the surface shape of an object to be inspected.

  As a method for inspecting the surface shape of an object to be inspected, an inspection method using a triangular measurement method using a laser displacement meter, a light cutting method using slit light, or the like is known. Patent Document 1 discloses a triangulation type that irradiates an inspection object with a laser beam, optically detects a spot image of the irradiated laser beam, and obtains the height of the spot image from the imaging position. A laser displacement meter is described.

  However, the conventional inspection method using the above-described triangulation laser displacement meter or light cutting method has the following problems.

  The inspection method using the triangulation laser displacement meter has the advantage that the position inspection can be performed with high accuracy and the response time of the inspection is fast, but it can be inspected only at the point where the laser beam spot is hit. Since this is not possible, the spot shape is usually inspected by scanning the spot position. For this reason, the inspection time becomes very long, and it is difficult to use it as an actual inspection apparatus in terms of inspection efficiency.

  Further, Patent Document 2 describes a light cutting method in which a surface shape is inspected by irradiating a test object with slit light and detecting the scattered light with an imaging device. As an example, FIG. 6 shows a schematic configuration of an appearance inspection apparatus using such a light cutting method.

  Referring to FIG. 6, the appearance inspection apparatus includes an inspection stage 111 on which the inspection object 112 is fixed, a projection device 115 that irradiates slit light onto the inspection object 112, and scattered light from the inspection object 112. The imaging device 113 that forms an image on the imaging surface via the lens 114, and the processing device that controls the imaging device 113 and the projection device 115 and calculates the depth of the measurement site of the inspection object 112 from the output of the imaging device 113 117.

  The slit light from the projection device 115 is irradiated at a certain angle with respect to the surface of the inspection object 112, and a laser beam cutting line is formed on the surface. The scattered light from the part where the laser beam cutting line is formed is detected by the imaging device 113. The image of the slit scattered light formed on the imaging surface of the imaging device 113 corresponds to the unevenness of the surface of the inspection object 112. From the luminance signal output from the imaging device 113, the center of luminance of the slit scattered light imaged on the imaging surface is obtained and regarded as an image of the measurement site. The base line length (distance from the projection device 115 to the imaging device 113), the cutting angle (the angle between the slit light and the optical axis of the imaging device 113), and the angle between the optical axis of the imaging device 113 and the measurement surface. Use to obtain information about the depth of the measurement point by the principle of triangulation.

  In the inspection method using the light cutting method, the surface of the object to be inspected is scanned with a line-shaped laser beam, so that the inspection time is shorter than that in the inspection method using the triangulation laser displacement meter. However, this method has a problem that inspection accuracy is low. The problem will be specifically described below.

  As shown in FIG. 7, a laser beam line 16a is formed by irradiating the defect portion 20 having a depth H on the surface of the inspection object with a line-shaped laser beam from the slit light source at a certain angle. . In this case, as shown in FIG. 8, when the edge of the defective portion 20 on the side irradiated with the laser beam 1a is in a standing state, the laser beam 1a is blocked by the edge. For this reason, the reachable depth H1 of the laser beam from the slit light source is shallower than the depth H of the defect portion 20, and the measurement accuracy is reduced by the difference between the depth H1 and the depth H. .

Note that, even in the convex defect portion, if there is a portion where the laser beam is blocked, the portion cannot be measured, so that the measurement accuracy is reduced accordingly.
Japanese Patent Laid-Open No. 11-83453 Japanese Patent Laid-Open No. 05-60524

  An object of the present invention is to provide an appearance inspection apparatus and an appearance inspection method capable of solving the above-described problems and inspecting irregularities on the surface of an object to be inspected at high speed and with high accuracy.

  In order to achieve the above object, an appearance inspection apparatus according to the present invention includes a plurality of projection apparatuses that respectively irradiate a surface of an object to be inspected with a line-shaped convergent light beam from different directions, and a line shape from the plurality of projection apparatuses. An imaging device that images a plurality of first light cutting lines respectively formed on the surface of the object to be inspected by a convergent light beam, and an image that is output from the imaging device and images the plurality of first light cutting lines. And a processing device that calculates the height or depth of the irregularities formed on the surface of the inspection object based on the data.

  According to the above configuration, since the defective portion is irradiated from multiple directions with the linear convergent light flux, the portion where the convergent light flux is blocked is reduced as compared with the conventional inspection method using the light cutting method. Specifically, in FIG. 8, apart from the laser beam 1a, the laser beam is irradiated at an angle that sufficiently reaches the depth H. As a result, the measured value approaches the depth H, and the measurement accuracy increases accordingly.

  In the visual inspection apparatus, the plurality of first obtained by irradiating the reference plane of a member having a reference plane corresponding to the surface of the inspection object with a linear convergent light beam from the plurality of projection apparatuses. Reference image data obtained by imaging the plurality of second optical cutting lines corresponding to the optical cutting lines with the imaging device further includes a storage device in which the processing device includes the plurality of first optical lines. Corresponding to the regions corresponding to the plurality of first light cutting lines extracted from the image data obtained by imaging the light cutting line and the plurality of second light cutting lines extracted from the reference image data stored in the storage device You may make it calculate the height or depth of the said unevenness | corrugation based on the difference with the area | region to perform.

  According to said structure, without performing complicated image processing of calculating | requiring an approximate curve for every light cutting line, the area | region corresponding to each of the image data which imaged several 1st light cutting lines, and reference | standard image data It is possible to calculate the height or depth of the irregularities for the defect by simple image processing such as comparing the two.

  The visual inspection method of the present invention includes a first step of irradiating a surface of an object to be inspected with a plurality of line-shaped convergent light beams from different directions, and a surface of the object to be inspected by the plurality of line-shaped convergent light beams. The second step of imaging the plurality of first light cutting lines respectively formed, and the unevenness formed on the surface of the object to be inspected based on the image data obtained by imaging the plurality of first light cutting lines. And a third step of calculating a height or a depth. This appearance inspection method also has the same effect as the appearance inspection apparatus of the present invention described above.

  According to the present invention, there is an effect that the inspection object can be inspected with high accuracy while maintaining the advantage of high-speed inspection by the light cutting method.

  Of the present invention, the comparison using the reference image data does not require complicated image processing, so that the processing is simplified and the processing time is shortened accordingly. .

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration of an appearance inspection apparatus according to an embodiment of the present invention. This appearance inspection apparatus includes an inspection stage 11 to which the inspection object 12 is fixed, a driving device 19 that drives the inspection stage 11, and a line-shaped laser beam (corresponding to slit light) to the inspection object 12. Two projection devices 15a and 15b to irradiate, one imaging device 13 in which scattered light from the object 12 to be inspected is imaged on the imaging surface via the lens 14, these drive device 19, projection device 15a, 15b and the image pickup device 13 and a processing device 17 for calculating the height or depth of the unevenness on the surface of the inspection object 12, and a display for displaying the calculation result and image data taken by the image pickup device 13. Device 18.

  The inspected object 12 has a uniform surface and becomes a problem when the surface is uneven. Examples of the inspection object 12 include a blade for cleaning the surface of a photosensitive member used in an electrophotographic apparatus. This type of cleaning blade performs cleaning with its surface abutting against the surface of the photoreceptor, and if the surface is uneven, it causes cleaning failure.

  The inspection stage 11 can be moved in the XY directions by being driven by the driving device 19. The display device 18 is an existing display device such as a CRT or LCD. The imaging device 113 is an imaging unit represented by, for example, a CCD. As the lens 14, a lens on which an optical image by scattered light is accurately formed on the imaging surface of the imaging device 13, for example, a high resolution macro zoom lens using a perfocal optical system is used.

  The projection devices 15a and 15b generate line-shaped laser light, and are arranged so as to irradiate the inspection object 12 with line-shaped laser light from different directions. As a means for generating line-shaped laser light, a line illumination light source that converts laser light from a single-wavelength laser light source into line-shaped laser light using a cylindrical lens or a parallel slit is generally used. For example, a laser light source having a wavelength of 635 nm is used, but another light source may be used as long as it has a high light condensing property and can be imaged by the imaging device.

  The projection devices 15a and 15b and the imaging device 113 include a moving mechanism (not shown) that can move in the height method (Z direction). This moving mechanism may be provided in each of the projection devices 15a and 15b and the imaging device 113, or may be provided in a support portion to which the projection devices 15a and 15b and the imaging device 113 are fixed integrally. In the latter case, when the arrangement positions and angles of the projection devices 15a and 15b and the imaging device 113 are set, the height can be adjusted while maintaining the set arrangement positions and angles.

  Two laser beam cutting lines 16a and 16b as shown in FIG. 2 are formed by irradiating the surface of the inspection object 12 with line-shaped laser beams from the projection devices 15a and 15b. In FIG. 2, the laser beam cutting lines 16 a and 16 b are substantially parallel, and a part of each cutting line is hung on the defect portion (concave portion) 20. Scattered light from the portions where the laser beam cutting lines 16a and 16b are formed is formed on the imaging surface of the imaging device 13 via the lens 14, respectively. That is, an optical image is formed on the imaging surface of the imaging device 13 by the scattered light related to the two laser beam cutting lines 16a and 16b. The optical images related to the laser beam cutting lines 16 a and 16 b formed on the imaging surface in this way include a curved portion corresponding to the concave portion of the defect portion 20. For example, as shown in FIG. 3, the optical image of the laser beam cutting line formed on the plane portion is a straight line, and the optical image of the laser beam cutting line formed on the defect portion 20 corresponds to the concave portion of the defect portion 20. It becomes a curve. In FIG. 3, an optical image 16c is an optical image related to the laser beam cutting line 16a, and an optical image 16d is an optical image related to the laser beam cutting line 16b.

  The processing device 17 controls the movement of the inspection stage 11 by the drive device 19 to scan the surface of the inspection object 12 fixed to the inspection stage 11 with the line-shaped laser light from the projection devices 15a and 15b. Further, the processing device 17 calculates the height or depth of the unevenness on the surface of the inspection object 12 based on the output signal of the imaging device 13. Specifically, when the optical images 16c and 16d as illustrated in FIG. 3 are formed on the imaging surface, the processing device 17 obtains image data of the optical images 16c and 16d obtained from the output signal of the imaging device 13. The heights h1 and h2 of the curves corresponding to the recesses are obtained, and calculation processing using these and predetermined parameters (the cutting angle, the magnification of the lens 14, the width of the cutting line, etc.) is performed, so that the defect 20 Find the actual depth.

  The heights h1 and h2 are differences between a straight line portion of the optical image and a line parallel to the straight line portion that is in contact with the top of the curved line portion. Such a difference can be basically obtained by digital image processing. Specifically, a reference member (metal member) having the same type as the object to be inspected 12 and having no irregularities on the surface is used, and the surface of the reference member is actually scanned with a line-shaped laser beam from the projection devices 15a and 15b. As a result, reference image data (data of only a straight line without a curve) regarding the optical images of the laser beam cutting lines 16a and 16b is acquired in advance. Then, the heights h1 and h2 are calculated from the difference between the reference image data and the image data of the optical images 16c and 16d obtained from the inspection object 12. In addition, the heights h1 and h2 can also be calculated by obtaining and comparing approximate curves of the respective laser beam cutting lines, but in this case, image processing becomes complicated.

  Scanning with line-shaped laser light from the projection devices 15a and 15b is performed in steps of a constant step width in a direction intersecting (for example, orthogonal to) the length direction of the laser light cutting line. The reference image data is acquired for each scanning position (step position), and stored in a storage device (not shown) in association with information that can specify each scanning position. The processing device 17 can obtain the current scanning position from the amount of movement of the inspection stage 11, the step width, and the like. Further, when the processing device 17 scans the surface of the inspection object 12 with the line-shaped laser light from the projection devices 15a and 15b, the processing device 17 can read the reference image data corresponding to the current scanning position from the storage device. .

  Next, the operation of the appearance inspection apparatus according to the present embodiment will be specifically described.

  First, a metal member prepared in advance and having the same shape as the object to be inspected 12 and having no irregularities on the surface is fixed on the inspection stage 11. When a predetermined input operation is performed after the fixing, the processing device 17 starts taking in the reference image data. In capturing the reference image data, the surface of the metal member fixed on the inspection stage 11 is actually scanned with a line-shaped laser beam from the projection devices 15a and 15b. Scanning is performed in increments of a constant step width, and at each scanning position, reference image data of optical images of the laser beam cutting lines 16a and 16b (in this case, only a straight line without a curve) is obtained. The scanning position is stored in a storage device (not shown) in association with information capable of specifying the scanning position.

  Next, the inspection object 12 is fixed on the inspection stage 11 instead of the metal member. After the fixing, when a predetermined input operation is performed, an appearance inspection of the inspection object 12 is performed by the processing device 17. FIG. 4 shows the procedure of this appearance inspection.

  In the appearance inspection, first, the inspection object 12 fixed on the inspection stage 11 is irradiated with the line-shaped laser light from the projection devices 15a and 15b (step S1). Subsequently, the laser beam cutting lines 16a and 16b formed by the laser beam irradiation are imaged (step S2). Subsequently, portions corresponding to the laser beam cutting lines 16a and 16b are extracted from the image data obtained by imaging (step S3). The extraction of the laser beam cutting line from the image data in step S3 is performed based on the luminance value of the image data. Specifically, since the luminance value is high in the region corresponding to the laser beam cutting line, the region is extracted by extracting a region having a certain threshold value or more. At this time, when the width of the extracted region (the width of the laser beam cutting line) changes in the length direction (the length direction of the laser beam cutting line), it is desirable to take an average of the widths. The average width is obtained by taking measurement points at regular intervals in the length direction for the extracted region, and taking the average of the width values at each measurement point.

  Subsequently, reference image data corresponding to the current scanning position is taken out from a storage device (not shown), a portion corresponding to the laser beam cutting line is extracted from the reference image data, and the laser beam cutting line extracted in step S3 Compare (step S4). Subsequently, position information in the height direction is detected based on the comparison result (difference) (step S5). Thereafter, the inspection stage 11 is moved by a certain step width (step S6), and the process returns to step S1. By repeating these steps S1 to S6, the entire surface of the inspection object 12 can be inspected.

  In the comparison in step S4 described above, when the defect portion 20 does not exist in the region where the laser beam cutting lines 16a and 16b are formed on the surface of the inspection object 12, the optical images 16c and 16d have only a straight line without a curve. Will be. In this case, the region corresponding to each laser beam cutting line of the image data acquired from the inspection object 12 is the same as the reference image data, and the difference (comparison result) between the two image data is almost “0”. On the other hand, when the defect part 20 exists in the region where the laser beam cutting lines 16a and 16b are formed on the surface of the inspection object 12, the optical images 16c and 16d are, as shown in FIG. And a curved portion corresponding to the concave portion of the defective portion 20. In this case, h1 and h2 are obtained from the difference between the image data acquired from the inspection object 12 and the reference image data, and the depth of the defective portion 20 is obtained by performing arithmetic processing using the h1 and h2 and a predetermined parameter. be able to.

  In the above-described appearance inspection, it is necessary to narrow the width of each laser beam cutting line to some extent. If the width of the laser beam cutting line is less than 10 μm, it is necessary to use an expensive optical system in order to obtain such a line width, which increases the cost of the apparatus. When the width of the laser beam cutting line is made larger than 15 μm, the accuracy of difference extraction by image comparison is lowered. For this reason, the preferred width of each laser beam cutting line is in the range of 10 to 15 μm.

  As described above, the feature of the appearance inspection apparatus according to the present embodiment is that a plurality of laser beam cutting lines are formed by irradiating line-shaped laser beams from different directions, and an inspection object is formed using these laser beam cutting lines. The surface of the substrate is scanned with a constant step width, and at each scanning position, each laser beam cutting line is imaged by one imaging device, and the obtained image data is compared with the reference data to obtain information on the uneven shape. The point is to obtain (height or depth). According to this feature, the information (height or depth) of the concavo-convex shape can be obtained with higher accuracy than in the case where the surface of the inspection object is scanned with one laser beam cutting line.

  Hereinafter, the difference in measurement accuracy between the case of scanning with two laser beam cutting lines (form A) and the case of scanning with one laser beam cutting line (form B) will be specifically described.

  In form A, in the apparatus configuration shown in FIG. 1, the irradiation angle (incident angle with respect to the measurement surface) of the line-shaped laser light from the projection apparatuses 15a and 15b is set to 38.0 °, and the surface is shown in FIG. The appearance inspection of the inspection object 12 in which the defective part 20 exists was performed.

  FIG. 5 shows a state in which the line-shaped laser light from the projection devices 15a and 15b is irradiated onto the defect portion 20, and shows a cross section in a direction intersecting the laser light cutting line. The line-shaped laser beam 1a from the projection device 15a and the line-shaped laser beam 1b from the projection device 15b are applied to the defect portion 20 from opposite directions. The defect portion 20 is a concave portion having a depth H of 30 μm, in which one edge portion is raised and the other edge portion is gently inclined.

  Since the laser beam is blocked by one of the edge portions of the defect portion 20 from the direction in which the laser beam 1a is irradiated, the reachable depth H1 is shallower than the depth H of the defect portion 20. It becomes. On the other hand, since the laser beam is not blocked by the edge portion from the direction in which the laser beam 1b is irradiated, the reachable depth H2 is equal to the depth H of the defect portion 20.

  The height h1 is obtained from the difference between the image data relating to the laser beam cutting line formed by the laser beam 1a and the reference image data. Further, the height h2 is obtained from the difference between the image data relating to the laser beam cutting line formed by the laser beam 1b and the reference image data. The actual depths H1 and H2 are calculated by performing arithmetic processing including predetermined parameters for each of the heights h1 and h2 thus obtained. In the example of FIG. 5, the reachable depth H <b> 2 of the laser beam 1 b is approximately the same as the depth H of the defect portion 20, and thus the measured value in this case is a value close to the depth H. In actual measurement, the depth H2 was 30 μm.

  In the form B, the appearance inspection of the inspection object 12 was performed using only the projection device 15a in the apparatus configuration of the form A. In this case, as shown in FIG. 8, the measurement is performed at a depth H1 at which the laser beam 1a can be reached. Since the reachable depth H1 of the laser beam 1a is shallower than the depth H of the defect portion 20, the measured value in this case is shallower than the depth H. In actual measurement, the depth H1 was 26 μm.

  From the measurement results of the above-described forms A and B, it can be seen that when scanning with two laser beam cutting lines, the accuracy is improved by about 4 μm as compared with scanning with one laser beam cutting line. Thus, by using a plurality of laser beam cutting lines, the inspection accuracy can be brought close to the accuracy of the laser depth meter, and more accurate measurement can be performed than the conventional one.

  The appearance inspection apparatus described above is an example of the present invention, and the configuration and processing procedure can be changed as appropriate without departing from the spirit of the invention. For example, there may be three or more projection devices that emit line-shaped laser light. Furthermore, the arrangement position of each projection apparatus is not limited to the position shown in FIG. 1, and there are a plurality of laser light cutting lines to be formed, and any of them can be captured by one imaging apparatus. Such an arrangement may be adopted.

  In the embodiment described above, the laser beam cutting lines formed on the surface of the object to be inspected are substantially parallel to each other as shown in FIG.

  Furthermore, it is desirable that the projection device 15 is set so that only the scattered light can be imaged from the viewpoint of making the light amounts of the plurality of laser light cutting lines 16 to be imaged constant.

  Further, the irradiation angle of the projection devices 15a and 15b, that is, the cutting angle (the angle formed between the irradiated slit light and the line perpendicular to the measurement surface of the inspection object 12) is determined by the width of the laser beam cutting line and the imaging device 13. It determines from the relationship with the measurement resolution regarding the heights h1 and h2 in the image data imaged by. Here, the measurement resolution includes a resolution unique to the imaging apparatus (camera) and a resolution that varies depending on an arrangement angle of the imaging apparatus. The optimum value of the relationship between the cutting angle and the measurement resolution can be obtained experimentally. The range of the cutting angle can be set in the range of 0 to 90 °, but more preferably, it is set in the range of 30 to 60 ° in consideration of the resolution and the width of the laser beam cutting line.

  Moreover, you may make it mutually differ the irradiation angle (incident angle with respect to the surface) of the laser beam which forms a laser beam cutting line.

  In the above description, the depth of the concave portion on the surface of the object to be inspected is calculated, but the height of the convex portion can also be calculated. When calculating the height, the processing procedure is the same as that for calculating the depth, and the same effects are obtained.

  When the object to be inspected is a flat surface with an ideal surface state, such as a cleaning blade, a reference member having a surface with a uniform flat surface is used. In this case, if the angle and the arrangement position of the imaging device and the projection device are fixed and the height from the surface of these devices does not change, the reference image data is the same at any scanning position. Therefore, in this case, one reference image data acquired at an appropriate scanning position may be stored in the storage device.

  Further, when the object to be inspected is an object whose ideal surface state is not a uniform plane, a reference member having the ideal surface state is used. In this case, reference image data is acquired and stored in a storage device for each scanning position. The appearance inspection in this case is the same processing procedure as in the above-described embodiment.

It is a block diagram which shows schematic structure of the external appearance inspection apparatus which is one Embodiment of this invention. It is a schematic diagram which shows the laser beam cutting line formed in the external appearance inspection apparatus shown in FIG. It is a schematic diagram which shows the optical image imaged on the imaging surface of the laser beam cutting line shown in FIG. It is a flowchart which shows the process sequence of the external appearance inspection performed in the external appearance inspection apparatus shown in FIG. It is a schematic diagram which shows a mode that the laser beam from the projection apparatus in the external appearance inspection apparatus shown in FIG. 1 is irradiated to a defective part. It is a block diagram which shows schematic structure of the conventional external appearance inspection apparatus. It is a schematic diagram which shows the laser beam cutting line formed in the conventional external appearance inspection apparatus shown in FIG. It is a schematic diagram which shows a mode that the laser beam from one projector is irradiated to a defect part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Inspection stage 12 Inspected object 13 Imaging device 14 Lens 15a, 15b Projection device 17 Processing device 18 Display device 19 Drive device

Claims (6)

A plurality of projection devices each irradiating the surface of the object to be inspected from different directions with a linear convergent light beam; and
An imaging device for imaging a plurality of first light cutting lines respectively formed on the surface of the object to be inspected by a linear convergent light beam from the plurality of projection devices;
A processing device that calculates the height or depth of the irregularities formed on the surface of the object to be inspected based on image data obtained by imaging the plurality of first light cutting lines output from the imaging device; An appearance inspection apparatus comprising: Corresponding to the plurality of first light cutting lines obtained by irradiating the reference plane of a member having a reference plane corresponding to the surface of the object to be inspected with linear convergent light beams from the plurality of projection devices. Reference image data obtained by imaging the plurality of second light cutting lines by the imaging device further includes a storage device in which the reference image data is stored in advance.
The processing device extracts the region corresponding to the plurality of first light cutting lines extracted from the image data obtained by imaging the plurality of first light cutting lines and the reference image data stored in the storage device. The appearance inspection apparatus according to claim 1, wherein the height or depth of the unevenness is calculated based on a difference from a region corresponding to the plurality of second light cutting lines.   The appearance inspection apparatus according to claim 1, wherein the incident angle of the linear convergent light beam irradiated from the plurality of projection apparatuses with respect to a surface of the inspection object is different. A first step of irradiating the surface of the object to be inspected with a plurality of line-shaped convergent light beams from different directions;
A second step of imaging a plurality of first light cutting lines respectively formed on the surface of the inspection object by the plurality of line-shaped convergent light beams;
And a third step of calculating the height or depth of the irregularities formed on the surface of the object to be inspected based on image data obtained by imaging the plurality of first light cutting lines. A plurality of second light beams corresponding to the plurality of first light cutting lines obtained by irradiating the plurality of line-shaped convergent light beams onto the reference surface of a member having a reference surface corresponding to the surface of the inspection object. Further comprising imaging a light cutting line of
In the third step, the region corresponding to the plurality of first light cutting lines extracted from the image data obtained by imaging the plurality of first light cutting lines and the plurality of second light cutting lines are imaged. The visual inspection method according to claim 4, further comprising a step of calculating a height or a depth of the unevenness based on a difference from an area corresponding to the plurality of second light cutting lines extracted from the reference image data. . 6. The appearance inspection method according to claim 4, wherein the incident angles of the plurality of line-shaped convergent light beams with respect to the surface of the inspection object are made different from each other.

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