KR101133641B1 - Method of inspecting three-dimensional shape - Google Patents

Abstract

The three-dimensional shape inspection method for a predetermined element formed on a printed circuit board may include generating a shadow template that abstracts a shadow of a predetermined element, irradiating a grid image light to a measurement object in a plurality of directions, and each pixel of the measurement object. Obtaining a shadow information of each star, merging shadow information of each pixel photographed from a plurality of directions, generating a shadow map, and comparing the shadow map of the measurement object with the shadow template, and corresponding to the shadow template on the measurement object. Obtaining information of the. Therefore, it is possible to accurately extract the elements on the printed circuit board.

Description

3D shape inspection method {METHOD OF INSPECTING THREE-DIMENSIONAL SHAPE}

The present invention relates to a three-dimensional shape inspection method, and more particularly to a three-dimensional shape inspection method for a device on a printed circuit board.

In general, at least one printed circuit board (PCB) is provided in an electronic device, and includes a device such as a chip on the printed circuit board.

Extracting an element such as the chip from the printed circuit board is necessary to determine whether the element mounted on the printed circuit board is defective or whether the pad connected to the element is defective.

Conventionally, the image taken by taking a two-dimensional image for the above extraction operation has been used. However, the task of extracting a specific device from a two-dimensional image is sensitive to the color or illumination of the device, making it difficult to distinguish the device from the surroundings, and it is difficult to distinguish the device even when the dimension of the device is changed. In addition, when there is noise in an image, for example, when a pattern or silk is formed on a substrate other than the device, it may be difficult to distinguish the device, and noise may be generated by a camera inside the device. It can also be confused with adjacent parts.

Therefore, a three-dimensional shape inspection method using an element extraction method that can prevent the above problems is required.

Therefore, the problem to be solved by the present invention is to provide a three-dimensional shape inspection method that can accurately extract the desired device.

In accordance with an exemplary embodiment of the present invention, a three-dimensional shape inspection method includes generating a shadow template that abstracts a shadow of a predetermined device, irradiating a grid image light to a measurement object in a plurality of directions, and each pixel of the measurement object. Obtaining star shadow information, merging the shadow information for each pixel photographed from a plurality of directions, generating a shadow map, and comparing the shadow map of the measurement object with the shadow template to measure the measurement. Obtaining information of the device corresponding to the shadow template from an object.

In one embodiment, the three-dimensional shape inspection method may further include obtaining the visibility information for each pixel of the measurement object by irradiating the grid image light in a plurality of directions to the measurement object, The generating of the shadow map may include generating a preliminary shadow map according to the shadow information for each pixel, excluding the device portion from the preliminary shadow map by using the visibility information, and removing the device portion. And determining the gripper map.

In an embodiment, the obtaining of information of the device corresponding to the shadow template from the measurement object may include determining whether the device corresponding to the shadow template exists on the measurement object and the device is the If present in the object to be measured may include obtaining the size, position and rotation angle information of the device. In this case, determining whether the device corresponding to the shadow template is present in the measurement object, setting a predetermined inspection area on the printed circuit board on which the device is formed and initializing the position of the shadow template And sequentially comparing from the gripper map while moving sequentially. In this case, the step of comparing the position of the shadow template with the shadow map while sequentially moving from the initial position, the value set to 0, 1 according to the pixel coordinates on the shadow template on the portion overlapping with the gripper map Multiplying the values set by 0 and 1 according to the pixel coordinates and multiplying each other, setting a position representing the maximum value according to the sequential movement of the position of the shadow template as a preliminary position where the device exists and the maximum value If the reference value is more than the reference value may include determining that the device corresponding to the shadow template.

In an embodiment, the three-dimensional shape inspection method may further include determining whether the device corresponding to the shadow template is defective after acquiring information of the device corresponding to the shadow template from the measurement object. It may include. In this case, when the device includes a chip formed on a printed circuit board, the determining of whether the device corresponding to the shadow template is defective may include extracting a chip body which is a body of the chip. The method may include: removing chip body information about the chip body from chip information about the chip and determining whether the chip formed on the printed circuit board is defective from chip information from which the chip body information is removed. It may include.

For example, the shadow template may be defined by a template determinant including dimensions of the device and an irradiation angle of grid image light irradiated to the measurement object. In this case, the shadow map and the shadow template may be compared within a predetermined allowance of the template determinant.

According to the present invention, since the desired device is extracted by using the shadow map according to the shadow of the device, the device is not sensitive to the color or illumination of the device as compared with the case of extracting the device using a 2D image, and is easy even when the dimension of the device is changed. The device can be discriminated.

In addition, the image may not be affected by noise such as a pattern or silk around the device, or noise caused by a camera inside the device, and compared with the template even when there are other devices around the device such as pad areas. Since the device is discriminated, the device can be extracted accurately.

In addition, even when the height of the device exceeds a predetermined measurable range, the shadow is generated regardless of the measurable range of the device, so that the position, size, rotation information, etc. of the device can be obtained more clearly regardless of the height of the device. Can be.

1 is a conceptual diagram illustrating an exemplary three-dimensional shape measuring apparatus used in the three-dimensional shape measuring method according to an embodiment of the present invention.
2 is a flowchart illustrating a three-dimensional shape inspection method according to an embodiment of the present invention.
3 is a schematic diagram illustrating an example of a shadow template.
4 is a flowchart illustrating an embodiment of a method of generating a shadow map using visibility information.
FIG. 5 is a flowchart illustrating an embodiment of a method of obtaining information of a device in FIG. 2.
FIG. 6 is a conceptual diagram illustrating an embodiment of a method of comparing whether a target device corresponds to a shadow template.

As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described in the specification, and that one or more other features It should be understood that it does not exclude in advance the possibility of the presence or addition of numbers, steps, actions, components, parts or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art.

Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

1 is a conceptual diagram illustrating an exemplary three-dimensional shape measuring apparatus used in the three-dimensional shape measuring method according to an embodiment of the present invention.

Referring to FIG. 1, the three-dimensional shape measuring apparatus used in the three-dimensional shape measuring method according to the present embodiment includes a measurement stage unit 100, an image photographing unit 200, first and second lighting units 300 and 400, The image acquirer 500, the module controller 600, and the central controller 700 may be included.

The measurement stage unit 100 may include a stage 110 for supporting the measurement object 10 and a stage transfer unit 120 for transferring the stage 110. In the present exemplary embodiment, the measurement object 10 is moved by the stage 110 with respect to the image capturing unit 200 and the first and second lighting units 300 and 400. The measuring position at can be changed.

The image capturing unit 200 is disposed above the stage 110 and receives the light reflected from the measurement object 10 to measure an image of the measurement object 10. That is, the image capturing unit 200 receives the light emitted from the first and second lighting units 300 and 400 and reflected from the measuring object 10 to take a plane image of the measuring object 10. .

The image capturing unit 200 may include a camera 210, an imaging lens 220, a filter 230, and a lamp 240. The camera 210 receives the light reflected from the measurement object 10 to take a planar image of the measurement object 10. For example, one of a CCD camera and a CMOS camera may be employed. The imaging lens 220 is disposed under the camera 210 to form light reflected from the measurement object 10 in the camera 210. The filter 230 is disposed below the imaging lens 220 to filter the light reflected from the measurement object 10 to provide the imaging lens 220, and for example, a frequency filter, a color filter, and light. It may be made of any one of the intensity control filter. The lamp 240 is circularly disposed under the filter 230, for example, to provide light to the measurement object 10 to capture a specific image such as a two-dimensional shape of the measurement object 10. Can be.

The first lighting unit 300 may be disposed to be inclined with respect to the stage 110 supporting the measurement object 10 on the right side of the image capturing unit 200, for example. The first lighting unit 300 may include a first lighting unit 310, a first grating unit 320, a first grating transfer unit 330, and a first condensing lens 340. The first lighting unit 310 is composed of an illumination source and at least one lens to generate light, the first grating unit 320 is disposed below the first lighting unit 310 to the first illumination The light generated in the unit 310 is changed into the first lattice pattern light having the lattice pattern. The first grating transfer unit 330 is connected to the first grating unit 320 to transfer the first grating unit 320, for example, one of the PZT (Piezoelectric) transfer unit or fine linear transfer unit It can be adopted. The first condenser lens 340 is disposed under the first grating unit 320 to condense the first grating pattern light emitted from the first grating unit 320 to the measurement object 10.

The second lighting unit 400 may be disposed to be inclined with respect to the stage 110 supporting the measurement object 10 on the left side of the image capturing unit 200, for example. The second lighting unit 400 may include a second lighting unit 410, a second grating unit 420, a second grating transfer unit 430, and a second condensing lens 440. Since the second lighting unit 400 is substantially the same as the first lighting unit 300 described above, detailed descriptions thereof will be omitted.

The first lighting unit 300 irradiates the N first grating pattern lights to the measurement target 10 while the first grating transfer unit 330 moves the first grating unit 320 N times in sequence. In this case, the image capturing unit 200 may photograph the N first pattern images by sequentially receiving the N first grating pattern lights reflected from the measurement object 10. In addition, the second lighting unit 400 moves N second grid pattern lights to the measurement target 10 while the second grid transfer unit 430 moves the second grid unit 420 sequentially N times. When irradiating, the image capturing unit 200 may photograph the N second pattern images by sequentially applying the N second grid pattern lights reflected from the measurement object 10. Here, N is a natural number, for example, may be 3 or 4.

Meanwhile, in the present exemplary embodiment, only the first and second lighting units 300 and 400 are described as an illumination device for generating the first and second grid pattern lights. Alternatively, the number of the lighting units may be three or more. That is, the grid pattern light irradiated to the measurement object 10 may be irradiated from various directions, and various kinds of pattern images may be photographed. For example, when three lighting units are arranged in an equilateral triangle shape around the image capturing unit 200, three grid pattern lights may be applied to the measurement object 10 in different directions, and four lighting units may be applied. When they are arranged in a square shape around the image capturing unit 200, four grid pattern lights may be applied to the measurement object 10 in different directions.

The image acquisition unit 500 is electrically connected to the camera 210 of the image capturing unit 200 to obtain and store the pattern images from the camera 210. For example, the image acquisition unit 500 includes an image system that receives and stores the N first pattern images and the N second pattern images photographed by the camera 210.

The module controller 600 is electrically connected to and controlled by the measurement stage unit 100, the image capturing unit 200, the first lighting unit 300, and the second lighting unit 400. The module controller 600 includes, for example, a lighting controller, a grid controller, and a stage controller. The lighting controller generates light by controlling the first and second lighting units 310 and 410, respectively, and the grid controller controls the first and second grid transfer units 330 and 430, respectively. The second grid units 320 and 420 are moved. The stage controller may control the stage transfer unit 120 to move the stage 110 up, down, left, and right.

The central control unit 700 is electrically connected to the image acquisition unit 500 and the module control unit 600 to control each. Specifically, the central control unit 700 receives the N first pattern images and the N second pattern images from the image system of the image acquisition unit 500, processes them, and processes the three-dimensional image of the object to be measured. The shape can be measured. In addition, the central controller 700 may control the lighting controller, the grid controller, and the stage controller of the module controller 600, respectively. As such, the central control unit may include an image processing board, a control board, and an interface board.

Hereinafter, a method of inspecting a predetermined device mounted on a printed circuit board employed as the measurement target 10 using the above-described three-dimensional shape measuring apparatus will be described in more detail.

2 is a flowchart illustrating a three-dimensional shape inspection method according to an embodiment of the present invention, Figure 3 is a schematic diagram showing an example of a shadow template.

2 and 3, in order to inspect a predetermined device mounted on a printed circuit board, first, a shadow template 900 that abstracts the shadow of the device is generated (S210). The abstracted device 910 may include, for example, a hexahedral chip.

For example, the shadow template 900 abstracts the shadow that appears when the light is irradiated to the device 910 at a predetermined angle as shown in FIG. 3 so that the portion corresponding to the shadow of the device 910 is white, the device Portions that do not correspond to the shadow of 910 may be preset in black. In FIG. 3, the hatched portion corresponds to the shadow of the element 910. In this case, the shadow template 900 may be formed as a digital image and set to have a value of 1 for white and a value of 0 for black.

The shadow template 900 may be defined by a template determinant. That is, the template determinant may determine the shadow template 900. For example, when the device 910 is a hexahedral chip, the dimension of the chip and the irradiation angle of the grid image light irradiated to the measurement object are determined. It may include. Specifically, the template determinant may include a horizontal length (X), a vertical length (Y) and a height (not shown) of the chip corresponding to the dimensions of the chip, the length and height of the horizontal and vertical The shadow template 900 may be defined by a template determinant including a.

Subsequently, the grid image light is irradiated to the measurement object in a plurality of directions to obtain shadow information for each pixel of the measurement object (S220).

Shadow information for each pixel of the measurement object may be easily obtained from data obtained by measuring the measurement object by the three-dimensional shape measuring apparatus illustrated in FIG. 1.

Next, a shadow map is generated by merging the shadow information for each pixel photographed from a plurality of directions (S230). For example, in the case of a three-dimensional shape measuring apparatus which forms a predetermined inclination angle and measures the measurement object in four directions, a comparison target element located on the measurement object in four directions (hereinafter referred to as a "target element") The shadow of is formed, and when merged, a shadow map that surrounds the target device may be obtained. For example, the shadow map may be configured to be set to 1 if a shadow exists or 0 if a shadow does not exist according to the presence or absence of a shadow according to pixel coordinates.

remind The shadow map is independent of the height measurement range even when the element 910 is greater than or equal to a predetermined height to exceed the height measurement range of the 3D shape measuring device, and thus the device is more clearly defined regardless of the height of the element 910. The position, size, rotation information, and the like of 910 may be obtained.

In this case, since the shadow map is created according to the shadow of the target element, the shadow map is independent of the color of the target element, letters or graphics printed on the target element, and also independent of the color, print shape, etc. of the surroundings of the target element. . That is, since the target device displays only light and dark levels depending on the presence of shadows, it is possible to determine the shape of the target device more clearly than a general two-dimensional image.

Meanwhile, in order to more clearly inspect the target device, visibility information for each pixel of the measurement object may be obtained and used.

The Visionary Stability is according to the brightness signal of the video it means a ratio of the amplitude average _{(A i (x, y)} ) of _{(B i (x, y)} ) , and there is generally a tendency to increase as the reflectance increases. The Visionary Stability _{(V i (x, y)} ) is defined as follows:

V _i (x, y) = B _i (x, y) / A _i (x, y)

Lattice pattern light may be irradiated onto the printed circuit board in various directions to capture various types of pattern images. As illustrated in FIG. 1, N patterns of the image acquisition unit 500 photographed by the camera 210 are photographed. From the images, N brightness degrees I ⁱ ₁ , I ⁱ ₂ , ..., I ⁱ _N at each position i (x, y) of the XY coordinate system are extracted, and the N-bucket algorithm (N The average brightness (A _i (x, y)) and viability (V _i (x, y)) are calculated using the -bucket algorithm.

For example, when N = 3 and when N = 4, viability can be calculated as follows, respectively.

In other words, when N = 3,

Can be calculated as

If N = 4,

It can be calculated as

The visibility information may be obtained by irradiating the measurement object with the grid image light in a plurality of directions in the same manner as in operation S220 of obtaining shadow information for each pixel of the measurement object. That is, the visibility information for each pixel can also be easily obtained from the data measured by the measurement object by the three-dimensional shape measuring apparatus shown in FIG. 1 as an example.

4 is a flowchart illustrating an embodiment of a method of generating a shadow map using visibility information.

Referring to FIG. 4, in order to generate the shadow map, first, a preliminary shadow map according to the shadow information is generated for each pixel (S232). Subsequently, the device 910 is excluded from the preliminary shadow map by using the visibility information (S234). Next, the gripper map from which the portion of the device 910 is excluded is determined (S236).

In general, in the case of a device whose reflectance is larger than its surroundings, the visibility is much larger than its surroundings. Therefore, when the visibility information is reflected in the shadow map, the color of the device 910 is black similar to the shadow color. Even shadows can be distinguished more clearly.

Referring back to FIG. 2, next, the shadow map of the measurement object and the shadow template 900 are compared to obtain information of the device 910 corresponding to the shadow template 900 in the measurement object. (S240). Information on the device 910 may include whether the device 910 exists, an actual size and an arrangement state of the device 910.

FIG. 5 is a flowchart illustrating an embodiment of a method of obtaining information of a device in FIG. 2.

2 and 5, in order to obtain information of the device 910 corresponding to the shadow template 900 in the measurement object, the device 910 corresponding to the shadow template 900 is first It may be determined whether or not present in the measurement object (S242).

For example, a predetermined inspection region (or region of interest) is set to check whether there is a target element, and then the existence of the target element is checked. In this case, the inspection area may be set by using CAD information that records the shape of the measurement object. The CAD information includes design information of the measurement object. In another embodiment, the inspection area may be set using learning information obtained by the learning mode. The learning mode is to obtain the design reference information of the printed circuit board by learning the bare board of the printed circuit board, it can be used to set the inspection area by obtaining the learning information through the learning mode.

FIG. 6 is a conceptual diagram illustrating an embodiment of a method of comparing whether a target device corresponds to a shadow template.

Referring to FIG. 6, in order to compare whether a target element 920 is an element 910 corresponding to the shadow template 900, first, a predetermined inspection area ROI is set on the printed circuit board. The position of the shadow template 900 may be compared with the shadow map while sequentially moving from the initial position 900a.

For the comparison, first, a value set to 0, 1 according to pixel coordinates, for example, on the shadow template 900 is multiplied by a value set to 0, 1 according to pixel coordinates on a portion overlapping with the shadow map. Add the values together. In this case, for example, as the overlapped portions between the hatched portions of the shadow template 900 and the shaded portions of the shadow map shown in FIG. 6 increase, the sum of the values multiplied with each other increases. Subsequently, according to the sequential movement of the position of the shadow template 900, a position representing the maximum value may be determined as a preliminary position in which the device 910 exists. At this time, for example, when the overlapped portion between the hatched portion of the shadow template 900 and the shaded portion of the shadow map shown in FIG. 6 is the most, the sum of the values multiplied with each other becomes the maximum. The shadow template 900 and the shadow map are almost identical. Next, if the maximum value is greater than or equal to the reference value, it may be determined that the target element 920 is the element 910 corresponding to the shadow template 900. For example, the reference value may be set to a value obtained by multiplying the number of pixels set to 1 of the shadow template 900 by a predetermined ratio.

The element 910 corresponding to the shadow template 900 has a predetermined size. The target element 920 of the measurement object may have a different size and may be disposed to be rotated. Accordingly, a predetermined tolerance for determining the device 910 and the target device 920 recorded in the shadow template 900 as the same device may be set, and the shadow map and the shadow template 900 may be The template determinants may be compared within a predetermined allowance. For example, the predetermined tolerance may have a value of a width X and a length Y and a width W in a range of 50% to 150% of the element 910 corresponding to the shadow template 900. have. Here, the width W may be the same in all directions but may be different in each direction. In addition, a predetermined rotation angle for determining the device 910 corresponding to the shadow template 900 and the target device as the same device may be set, and the shadow map and the shadow template 900 may be configured to have the predetermined rotation angle. Can be compared while rotating.

Referring back to FIG. 5, when the device 910 is present in the measurement object, information about the size, position, and rotation angle of the device, that is, the target device 920 may be obtained (S244). Such information can be easily obtained using the shadow map.

On the other hand, after acquiring the information of the device 910 corresponding to the shadow template 900 from the measurement object (S140), the information of the device 910 is determined in various ways in a three-dimensional inspection method. Can be utilized.

For example, it may be determined whether the device corresponding to the shadow template 900 is defective by using the information of the device 910 (S250).

That is, it is possible to determine whether the device is defective by checking whether the device is properly disposed on the measurement object using the size information, the rotation information, and the like. Alternatively, the information of another device or part may be obtained by excluding the information about the device from the information of the measurement object by using the information of the device.

Meanwhile, a part of the device may be extracted and removed from the information of the device, and the remaining information of the removed device may be used to determine whether the device is defective.

For example, when the device is a chip formed on a printed circuit board, information of a terminal extending from the chip body except for the body of the chip and information of a pad connected to the terminal of the chip may be obtained without noise. It may be. Therefore, it is also possible to determine whether these parts are defective by using the information thus obtained.

In an embodiment, when the device is a chip formed on a printed circuit board, first, a chip body which is a body of the chip is extracted, and then chip body information for the chip body is removed from chip information for the chip. Next, from the chip information from which the chip body information is removed, it is possible to determine whether the chip formed on the printed circuit board is defective, that is, a connection state between the terminal of the chip and the pad.

As described above, according to the present invention, since the desired device is extracted using the shadow map according to the shadow of the device, the device is not sensitive to the color or lighting of the device as compared with the case of extracting the device using the 2D image, and the dimension of the device is changed. The device can be easily identified.

In addition, the image may not be affected by noise such as a pattern or silk around the device, or noise caused by a camera inside the device, and compared with the template even when there are other devices around the device such as pad areas. Since the device is discriminated, the device can be extracted accurately.

In addition, even when the height of the device exceeds a predetermined measurable range, the shadow is generated regardless of the measurable range of the device, so that the position, size, rotation information, etc. of the device can be obtained more clearly regardless of the height of the device. Can be.

While the present invention has been described in connection with what is presently considered to be practical and exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Therefore, the above description and the drawings below should be construed as illustrating the present invention, not limiting the technical spirit of the present invention.

10: measuring object 100: measuring stage part
200: image capturing unit 300: first lighting unit
400: second lighting unit 500: image acquisition unit
600: module control unit 700: central control unit
900: shadow template 910: device
920 target element ROI: inspection area

Claims (8)

Generating a shadow template that abstracts a shadow of a predetermined device;
Irradiating grating image light to a measurement object in a plurality of directions to obtain shadow information for each pixel of the measurement object;
Merging the shadow information of each pixel photographed from a plurality of directions to generate a shadow map; And
And comparing the shadow map of the measurement object with the shadow template to obtain information of the device corresponding to the shadow template in the measurement object. The method of claim 1,
Illuminating the measurement object with the grid image light in a plurality of directions to obtain visibility information for each pixel of the measurement object,
Generating the shadow map,
Generating a preliminary shadow map according to the shadow information for each pixel;
Excluding the device portion from the preliminary shadow map using the visibility information; And
And determining the gripper map from which the device portion is excluded. The method of claim 1, wherein the obtaining of the information corresponding to the shadow template from the measurement object comprises:
Determining whether the element corresponding to the shadow template exists in the measurement object; And
And obtaining the size, position, and rotation angle information of the device when the device is present in the measurement object. The method of claim 3, wherein the determining of whether the element corresponding to the shadow template is present in the measurement object comprises:
Setting a predetermined inspection area on a printed circuit board on which the device is formed; And
And comparing the position of the shadow template with the gripper map while sequentially moving the position of the shadow template from an initial position. The method of claim 4, wherein comparing the shadow template with the shadow map while sequentially moving the position of the shadow template from an initial position includes:
Adding values obtained by multiplying a value set to 0 and 1 according to pixel coordinates on the shadow template by multiplying the value set to 0 and 1 according to pixel coordinates on a portion overlapping with the gripper map;
Setting a position indicating a maximum value as a preliminary position in which the device exists according to the sequential movement of the position of the shadow template; And
And determining that the device corresponds to the shadow template when the maximum value is greater than or equal to the reference value. The method of claim 1, wherein after obtaining information of the device corresponding to the shadow template from the measurement object,
And determining whether the device corresponding to the shadow template is defective. delete The method of claim 1,
The shadow template is defined by a template determinant including dimensions of the device and an irradiation angle of grid image light irradiated to the measurement object.
And the shadow map and the shadow template are compared within a predetermined allowable value of the template determinant.

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