Inspection device, inspection system and program

Abstract

To inspect a surface shape of an object to be inspected accurately at high speed.SOLUTION: An inspection device comprises: a control unit that obtains a photographic image obtained by photographing, with a photographing unit, an object to be inspected on which a projection pattern constituted of binary periodic images is projected from a projection unit; and an arithmetic processing unit that calculates a surface shape of the object to be inspected by multiplying the photographic image by an auxiliary image composed of continuous periodic gradations generated based on the photographic image obtained by the control unit.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an inspection device, an inspection system, and program Regarding. [Background technology]

[0002] In recent years, optical, non-contact types have become mainstream as three-dimensional shape inspection devices for measuring the surface shape of an object.

[0003] The pattern projection method, which is one of the non-contact measurement techniques, is a method for measuring the three-dimensional shape of an object to be inspected from a captured image in which a projection pattern is projected onto the entire surface of the object to be inspected (for example, see Patent Document 1). It is known that the pattern projection method makes it possible to measure the three-dimensional shape of an object to be inspected accurately in a relatively short time. Summary of the Invention [Problem to be solved by the invention]

[0004] However, although the pattern projection method has a shorter measurement time than other measurement techniques, it is still not sufficient to capture the surface shape of an object moving at high speed or instantaneous changes in the surface shape of the object.

[0005] The present invention has been made in view of the above, and an object of the present invention is to inspect the surface shape of an inspection object with high accuracy and at high speed. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present invention provides a control unit for obtaining a captured image of an object to be inspected, onto which a projection pattern composed of a binary periodic image is projected from a projection unit, by an imaging unit; and multiplying the captured image by an auxiliary image composed of a continuous periodic tone generated based on the captured image obtained by the control unit. , low-pass filter processing and a calculation processing unit that calculates the surface shape of the object to be inspected by the above-mentioned measurement. Effect of the Invention

[0007] The present invention has an effect of being able to inspect the surface shape of an object to be inspected with high accuracy and at high speed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration of an inspection system according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of a projection pattern. [Diagram 3] FIG. 3 is a block diagram showing a hardware configuration of the three-dimensional measuring apparatus. [Figure 4] FIG. 4 is a functional block diagram showing functions related to three-dimensional inspection processing. [Diagram 5] FIG. 5 is a flowchart showing the flow of the three-dimensional inspection process. [Figure 6] FIG. 6 is a schematic diagram showing the luminance distribution in a local region of a projection pattern. [Figure 7] FIG. 7 is a schematic diagram showing a captured image of a projection pattern. [Figure 8] FIG. 8 is a conceptual diagram showing an auxiliary image. [Figure 9] FIG. 9 is a diagram showing an example of a phase image. [Figure 10] FIG. 10 is a diagram showing an example of adjustment of the amount of light incident on an inspection object from the pattern projection device according to the second embodiment. [Figure 11] FIG. 11 is a diagram showing an example of a captured image of a projection pattern according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] With reference to the accompanying drawings, the following describes an inspection device, an inspection system, and program An embodiment of the present invention will now be described in detail.

[0010] (First embodiment) Fig. 1 is a diagram showing an example of the configuration of an inspection system 1 according to a first embodiment. As shown in Fig. 1, the inspection system 1 of the present embodiment includes a pattern projection device 10 which is a projection unit, an imaging device 20 which is an imaging unit, and a three-dimensional measuring device 30 which is an inspection device.

[0011] The pattern projection device 10 projects a projection pattern (see FIG. 2) composed of light and dark regions (binary periodic image) onto the surface of the inspection object 50. The inspection object 50 is, for example, an object having specular reflection characteristics that reflect light, such as a mirror body with a large curvature (for example, a spherical mirror or an aspherical mirror). The pattern projection device 10 has, for example, a display 10a that is an image display device with a wide radiation angle. The pattern projection device 10 projects a projection pattern displayed on the display 10a onto the inspection object 50 that is placed directly above the display 10a using a holding stand (not shown) or the like. Since it is necessary to project the projection pattern onto the entire measurement area of ​​the inspection object 50, the size of the inspection object 50 is set to a size that fits within the display 10a of the pattern projection device 10.

[0012] The imaging device 20 is a camera having an imaging element such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). As shown in Fig. 1, the imaging device 20 is installed at a position where the optical axis of the imaging device 20 with respect to the inspection object 50 is parallel to the display surface (projection surface) of the display 10a of the pattern projection device 10. By installing the imaging device 20 in this manner, the imaging device 20 can capture an image of the projection pattern specularly reflected by the inspection object 50. Note that "parallel" only needs to be substantially parallel, and may have an angle within a range that does not cause any problem in capturing an image of the projection pattern specularly reflected by the inspection object 50.

[0013] 1 shows an example in which the imaging device 20 is installed outside the pattern projection device 10, the present invention is not limited to this, and the imaging device 20 may be installed within the display surface (projection surface) of the display 10a of the pattern projection device 10. The distance between the imaging device 20 and the inspection target 50 may be determined according to the angle of view and focal length of the imaging device 20.

[0014] Here, the projection pattern will be described. FIG. 2 is a diagram showing an example of the projection pattern. FIG. 2(a) shows a projected image of the projection pattern, and FIG. 2(b) shows a captured image of the projection pattern. As shown in FIG. 2, the projection pattern is a periodic black and white checkered pattern (checkered pattern). The black and white checkered pattern (checkered pattern) is a pattern in which checkerboard-like lattice patterns are arranged in different colors. The smaller the size of the black lattice in the projection pattern, the more the measurement accuracy can be improved. The lower limit of the size of the lattice is determined by the resolution of the display 10a of the pattern projection device 10. Also, it is desirable that the size of the white lattice in the projection pattern is a size that can be resolved by the resolution of the imaging device 20.

[0015] The three-dimensional measuring device 30 is composed of a general PC (Personal Computer). The three-dimensional measuring device 30 connects the pattern projection device 10 and the imaging device 20. The three-dimensional measuring device 30 controls the projection of the projection pattern by the pattern projection device 10 and the imaging by the imaging device 20. The three-dimensional measuring device 30 analyzes the captured image of the inspection object 50 onto which the projection pattern is projected, captured by the imaging device 20. Then, the three-dimensional measuring device 30 reconstructs the three-dimensional shape based on phase information obtained by analyzing the captured image.

[0016] Next, the hardware configuration of the three-dimensional measuring device 30 will be described.

[0017] Here, Fig. 3 is a block diagram showing a hardware configuration of the three-dimensional measuring device 30. As shown in Fig. 3, the three-dimensional measuring device 30 is constructed by a computer. As shown in Fig. 3, the three-dimensional measuring device 30 includes a CPU (Central Processing Unit) 301, a ROM (Read Only Memory) 302, a RAM (Random Access Memory) 303, a HD (Hard Disk) 304, a HDD (Hard Disk Drive) controller 305, a display 306, an external device connection I / F (Interface) 308, a network I / F 309, a bus line 310, a keyboard 311, a pointing device 312, a DVD-RW (Digital Versatile Disc Rewritable) drive 314, and a media I / F 316.

[0018] Among these, the CPU 301 controls the operation of the entire coordinate measuring device 30. The ROM 302 stores programs such as an IPL used to drive the CPU 301. The RAM 303 is used as a work area for the CPU 301. The HD 304 stores various data such as programs. The HDD controller 305 controls reading or writing of various data from or to the HD 304 under the control of the CPU 301. The display 306 displays various information such as a cursor, a menu, a window, a character, or an image. The external device connection I / F 308 is an interface for connecting various external devices. In this case, the external devices are, for example, the pattern projection device 10, the imaging device 20, a USB (Universal Serial Bus) memory, a printer, and the like. The network I / F 309 is an interface for data communication using a communication network. The bus line 310 is an address bus, a data bus, or the like for electrically connecting each component such as the CPU 301 shown in FIG. 3.

[0019] The keyboard 311 is a type of input means having a plurality of keys for inputting characters, numbers, various instructions, etc. The pointing device 312 is a type of input means for selecting and executing various instructions, selecting a processing target, moving a cursor, etc. The DVD-RW drive 314 controls reading and writing of various data from a DVD-RW 313 as an example of a removable recording medium. Note that this is not limited to DVD-RW, and may be DVD-R, etc. The media I / F 316 controls reading and writing (storing) of data from a recording medium 315 such as a flash memory.

[0020] The program executed by the three-dimensional measuring device 30 of this embodiment is provided as a file in an installable or executable format recorded on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, or a DVD (Digital Versatile Disc).

[0021] The program executed by the three-dimensional measuring device 30 of this embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. The program executed by the three-dimensional measuring device 30 of this embodiment may be provided or distributed via a network such as the Internet. The program executed by the three-dimensional measuring device 30 of this embodiment may be provided by being pre-installed in a ROM or the like.

[0022] Next, functions relating to three-dimensional inspection processing will be described.

[0023] 4 is a functional block diagram showing functions related to the three-dimensional inspection process. As shown in FIG. 4, the three-dimensional measuring device 30 includes a control unit 35 and a calculation processing unit .

[0024] The control unit 35 includes a system control unit 350 , a pattern storage unit 351 , a projection driving unit 352 , an imaging control unit 353 , and a display control unit 354 .

[0025] The projection driving unit 352 drives the pattern projection device 10 under the control of the system control unit 350. The system control unit 350 controls the projection driving unit 352 so as to project the projection pattern onto the inspection target 50. The imaging control unit 353 controls the shooting conditions (exposure time, gain, storage format, etc.) and shooting timing of the imaging device 20 under the control of the system control unit 350. The display control unit 354 controls the display on the display 306 under the control of the system control unit 350.

[0026] The pattern storage unit 351 reads out pattern information (e.g., design, brightness, resolution, etc.) and projection timing for forming a projection pattern stored, for example, in the ROM 302 or HD 304 of the three-dimensional measuring device 30. The pattern storage unit 351 reads out the pattern information and projection timing and supplies them to the system control unit 350 under the control of the system control unit 350. The system control unit 350 controls the projection driving unit 352 based on the pattern information and projection timing supplied from the pattern storage unit 351.

[0027] The system control unit 350 synchronizes the projection timing of the pattern projection device 10 with the shooting timing of the imaging device 20 to capture an image of the object 50 to be inspected with the projection pattern projected onto it, and transmits the acquired image information to the calculation processing unit 36.

[0028] The arithmetic processing unit 36 ​​analyzes the image information supplied from the imaging device 20. The arithmetic processing unit 36 ​​performs analysis based on the image information supplied from the imaging device 20, and calculates phase information and three-dimensional reconstruction information of the inspection object 50. The arithmetic processing unit 36 ​​supplies the phase information and three-dimensional reconstruction information of the inspection object 50 to the control unit 35.

[0029] The system control unit 350 controls the display control unit 354 based on the restored three-dimensional information supplied from the calculation processing unit 36. The display control unit 354 displays the analysis image and a 3D representation of the inspection object 50 on the display 306 based on the restored three-dimensional information.

[0030] The arithmetic processing unit 36 ​​and the control unit 35 are realized by a program that runs on the CPU 301. Specifically, the CPU 301 realizes the arithmetic processing unit 36 ​​and the control unit 35 by reading and executing a program from the ROM 302 or HD 304.

[0031] Incidentally, a part or the whole of the arithmetic processing unit 36 ​​and the control unit 35 may be realized by hardware.

[0032] Next, the flow of the three-dimensional inspection process will be described in detail.

[0033] 5 is a flowchart showing the flow of the three-dimensional inspection process. Note that this is premised on the condition that an operator sets the inspection target 50 directly above the display 10a of the pattern projection device 10. The fixed position of the inspection target 50 is basically a position where the projected pattern reflected by the inspection target 50 is perpendicularly incident on the imaging device 20, but if the shape of the inspection target 50 is complex, it is desirable to determine detailed installation conditions through a prior evaluation.

[0034] First, the control unit 35 projects a projection pattern from the pattern projection device 10 onto the inspection object 50 (step S1). At the same time, the control unit 35 captures the projection pattern projected onto the inspection object 50 by the imaging device 20 (step S2). Note that the projection pattern is set to a size that allows a black and white checkered pattern (checkered pattern) to be sufficiently resolved according to the camera resolution of the imaging device 20.

[0035] Next, the arithmetic processing unit 36 ​​performs analysis of the captured image (step S3) and three-dimensional reconstruction (step S4).

[0036] Finally, the control unit 35 displays the analysis results such as the 3D restored image on the display 306 (step S5). If the operator recognizes an abnormality in the 3D restored image (Yes in step S5), remeasurement is performed from the pattern projection (step S1). If the operator does not recognize an abnormality in the 3D restored image (No in step S5), the process ends.

[0037] Here, the image analysis process in step S3 and the three-dimensional reconstruction process in step S4 will be described in detail.

[0038] First, the arithmetic processing unit 36 ​​performs background component removal and demodulation processing. It is assumed that the inspection object 50 has a continuous surface having specular reflection characteristics.

[0039] The calculation processing unit 36 ​​obtains a binary brightness image generated by the pattern projection device 10 for displaying the projection pattern from a captured image detected by the imaging device 20 via a continuous surface having specular reflection characteristics of the object to be inspected 50.

[0040] Here, Fig. 6 is a schematic diagram showing the luminance distribution in a local region of the projection pattern, and Fig. 7 is a schematic diagram showing a captured image of the projection pattern. As shown in Fig. 6, the minimum modulation period of the projection pattern is twice the pixel size of the pattern projection device 10. Fig. 7 is a schematic diagram showing the result of converting the projection pattern shown in Fig. 6 into a pixel output signal on the imaging element of the imaging device 20 via an inspection target 50 having specular reflection characteristics.

[0041] However, the purpose here is to conceptually explain the information processing method, and does not explicitly state the deformation of the projection pattern resulting from the shape of the inspection target 50. In the inspection system 1 of this embodiment, it is necessary to select the magnification of the optical system of the imaging device 20, the pixel size of the imaging element of the imaging device 20, the imaging lens of the imaging device 20, etc. so that the pixels of the imaging element can sufficiently resolve the period of the projection pattern reflected on the imaging element of the imaging device 20.

[0042] 7, one period of the projection pattern is resolved by 12 pixels on the imaging element of the imaging device 20. The projection pattern is independent of the pixel pitch of the imaging element of the imaging device 20. As a result, the boundary portion of the projection pattern does not fit completely within the pixels of the imaging element of the imaging device 20, resulting in an image with "blurring" as shown in FIG.

[0043] The captured image shown in Fig. 7 has discontinuity due to the binary information of the projection pattern. In other words, the captured image shown in Fig. 7 contains high spatial frequency components in the spatial frequency domain. This can be expressed as a formula, as shown in the following formula (1).

[0044]

number

[0045] Here, Nb(x,y) is the background component that does not reflect the photographed pattern, and I0(x,y) represents the envelope function of the photographed pattern. The series sums for m and n in parentheses are expressed using the Fourier series expansion form of the x and y components of a square wave with a duty ratio of 1. Φx(x,y) and Φy(x,y) represent phase terms that represent the deviation of the projection pattern from a periodic signal in the x and y directions that depends on the shape of the inspection target 50.

[0046] To recover the shape information of the object 50, it is necessary to remove the contributions of the background component Nb(x,y) and the envelope function I0(x,y) of the projection pattern, and further remove the vibrations having modulation frequencies given by odd multiples of the fundamental frequencies kx and ky, thereby extracting only the components that depend on Φx(x,y) and Φy(x,y).

[0047] In order to remove the above-mentioned unnecessary signals, the calculation processing unit 36 ​​generates an auxiliary image given by the following equation (2): The auxiliary image serves as a reference image for phase analysis.

[0048]

number

[0049] Fig. 8 is a conceptual diagram showing an auxiliary image generated by equation (2). While an image captured by the imaging element of the imaging device 20 has a rectangular profile as shown in Fig. 7 and equation (1), the auxiliary image generated by equation (2) is characterized by being a smooth function with a single spatial frequency. In other words, the auxiliary image is made up of continuous periodic gradations.

[0050] Next, the calculation processing unit 36 ​​multiplies equation (2) by equation (1) and removes the lower side of the modulation frequency kx or ky as a cutoff frequency using a low-pass filter, thereby obtaining a post-processed image as shown in equation (3) below.

[0051]

number

[0052] The arithmetic processing unit 36 ​​performs low-pass filtering to remove all components other than m=1 and n=1 in formula (1). In addition, since the background component Nb(x,y) is also shifted to the (kx,ky) position in the spatial frequency domain, the arithmetic processing unit 36 ​​also removes the background component Nb(x,y) by low-pass filtering. In this way, the arithmetic processing unit 36 ​​can remove the high-frequency components and background components caused by the binary image of the projection pattern included in formula (1) by multiplication with the auxiliary image and low-pass filtering. However, the approximation of formula (3) is subject to a constraint that Φx(x,y) and Φy(x,y) are composed of lower frequency components than the cutoff frequency min(kx,ky).

[0053] Similarly, the calculation processing unit 36 ​​generates images of the following expressions (4a), (4b), and (4c) as auxiliary images.

[0054]

number

[0055] Then, the calculation processing unit 36 ​​multiplies equation (1) by equations (4a), (4b), and (4c), respectively, and performs low-pass filter processing to generate post-processed images as shown in equations (5a), (5b), and (5c) below.

[0056]

number

[0057] Next, the calculation processing unit 36 ​​performs a phase extraction process and a phase unwrapping process.

[0058] The calculation processing unit 36 ​​derives phase images Φx(x, y) and Φy(x, y) reflecting the shape of the object to be inspected 50 from the post-processed images of equation (3) and equations (5a), (5b), and (5c) as shown in the following equations (6a) and (6b).

[0059]

number

[0060] The calculation processing unit 36 ​​may use the following expressions (7a) and (7b) for extracting the ±45° components.

[0061]

number

[0062] The reason why the ±45° components are used here is that the period of the projection pattern given in FIG. 6 or equation (1) is tilted in the ±45° direction, and extracting the phase in the ±45° direction helps to suppress the occurrence of errors during phase unwrapping, which will be described later.

[0063] Fig. 9 shows an example of a phase image obtained by the above-mentioned processing procedure. Fig. 9(a) is an original image of a sample in which a Pt film is formed on a silicon substrate as an inspection target 50. Fig. 9(b) is a phase image before phase unwrapping, in which the phase change in the +45° direction is expressed by the brightness distribution. By removing the background component and performing demodulation processing on the modulated image, a clear phase image was obtained over the entire surface of the sample.

[0064] Figure 9(c) shows a phase image after phase unwrapping, which expresses the phase change in the +45° direction using brightness distribution. The phase image obtained using equations (6a) and (6b) or equations (7a) and (7b) is folded over in the range of -π to π due to the domain of the arc tangent function. In order to restore an image corresponding to the shape information of the object from the phase image, a phase image with a smooth phase distribution without folding was obtained by performing phase unwrapping processing, as shown in Figure 9(c).

[0065] As described above, in order to obtain the three-dimensional shape of the inspection object 50 having specular reflection characteristics with high resolution, the deflectometry method, which is one of the pattern projection methods, is applied. In this embodiment, in order to obtain high spatial resolution, a checkered pattern in which black and white are inverted on a pixel-by-pixel basis of the pattern projection device 10 is used as the projection pattern. At this time, high-frequency components are superimposed on the spatial frequency, but by generating a group of auxiliary images that remove the high-frequency components and also remove the effects of the background components and the spatial distribution (envelope function) of the pattern illumination, and providing multiplication and low-pass filter processing, it is possible to extract a phase component that depends only on the shape of the inspection object 50. As a result, it is possible to improve the spatial resolution in shape measurement.

[0066] In this manner, in this embodiment, the three-dimensional shape of the inspection object 50 can be acquired from the captured image after one pattern projection, which has the effect of enabling high-speed (short time) inspection compared to methods that require multiple captures, such as the phase shift method. In addition, this embodiment employs a periodic black-and-white checkered pattern (checkered pattern) as the projection pattern, and a periodic structure can be formed from a minimum of two pixels, which has the effect of enabling the surface shape of the inspection object to be inspected with high accuracy compared to other patterns that require multiple pixels.

[0067] (Second embodiment) Next, a second embodiment will be described.

[0068] The second embodiment differs from the first embodiment in that the luminance of the pattern projection device 10 is adjusted. In the following description of the second embodiment, the description of the same parts as in the first embodiment will be omitted, and only the parts different from the first embodiment will be described.

[0069] 10A and 10B are diagrams showing an example of adjustment of the amount of light incident on the inspection object 50 from the pattern projection device 10 according to the second embodiment. As shown in Fig. 10A, when the size of the inspection object 50 is large and the distance from the display surface (projection surface) of the display 10a of the pattern projection device 10 varies depending on the location, the amount of light incident on the inspection object 50 from the display 10a of the pattern projection device 10 becomes non-uniform.

[0070] 10(a), an area close to the display 10a of the pattern projection device 10 is captured brightly, and an area far from the display 10a of the pattern projection device 10 is captured darkly, which may result in blown-out highlights or crushed shadows if the dynamic range of the imaging device 20 is exceeded. When the contrast of an image captured by the imaging device 20 becomes low in this way, signal components are buried in background noise, making it more likely that errors will occur in image analysis.

[0071] Therefore, as a countermeasure to this problem, in this embodiment, the brightness of the pattern projection device 10 is adjusted.

[0072] The system control unit 350 first controls the imaging device 20 under normal conditions via the imaging control unit 353 to capture an image. The calculation processing unit 36 ​​analyzes the contrast of the projection pattern in the image captured by the imaging device 20, and feeds back the analysis result to the system control unit 350.

[0073] Then, the system control unit 350 controls the projection driving unit 352 so as to adjust the amount of light emitted by the pattern projection device 10 based on the fed back analysis result of the contrast. Then, the system control unit 350 causes the imaging device 20 to perform re-imaging via the imaging control unit 353.

[0074] That is, as shown in FIG. 10(b), the system control unit 350 reduces the amount of light in areas of the display 10a of the pattern projection device 10 that are close to the object to be inspected 50 and increases the amount of light emitted in areas that are far from the object to be inspected 50, thereby improving the brightness unevenness of the captured image obtained.

[0075] In addition, if the shape of the object to be inspected 50 is complex and it is therefore impossible to know the correspondence between the light-emitting area of ​​the display 10a of the pattern projection device 10 and the light-receiving area of ​​the object to be inspected 50, this can be addressed by conducting a preliminary experiment in which photographs are taken while shifting the light-emitting area.

[0076] In addition, if the distance between the display 10a of the pattern projection device 10 and the object to be inspected 50 is not constant depending on the shape of the object to be inspected 50, or if there are uneven brightness in the projected pattern, differences in brightness will occur depending on the location of the captured image, and errors will be more likely to occur in image analysis in areas with low contrast.

[0077] As a countermeasure to this, the arithmetic processing unit 36 ​​may binarize the captured image. In this embodiment, the projection pattern projected onto the inspection object 50 is a black and white checkered pattern, which is information similar to a digital signal, and the pattern shape of the captured image is used for calculation during analysis in the arithmetic processing unit 36. In other words, since the pattern shape of the projection pattern alone can be obtained from a digital binary image, if the captured image can be appropriately binarized, improvement in accuracy can be expected. Note that there are various methods for binarization, and adaptive binarization in which a threshold is set locally is effective.

[0078] (Third embodiment) Next, a third embodiment will be described.

[0079] The third embodiment differs from the first and second embodiments in that the analysis region is divided. In the following description of the third embodiment, the description of the same parts as the first and second embodiments will be omitted, and only the parts different from the first and second embodiments will be described.

[0080] According to the measurement method of this embodiment, an auxiliary image is generated from the spatial frequency of the projection pattern obtained from the captured image to analyze the phase information, but in the captured image of the projection pattern projected onto the inspection target 50, which is a mirror body with a large curvature (for example, a spherical mirror or an aspheric mirror), the black and white pattern interval varies depending on the location. If the black and white pattern interval varies depending on the location in this way, the area that can be analyzed with one auxiliary image is limited, and there is a problem that the inspection area becomes narrow.

[0081] To address this issue, the present embodiment divides the analysis region.

[0082] Here, Fig. 11 is a diagram showing an example of a captured image of a projection pattern according to the third embodiment. First, the system control unit 350 controls the imaging device 20 under normal conditions via the imaging control unit 353 to capture an image, and obtains a captured image of the projection pattern projected onto the inspection target 50, which is a mirror body having a curvature, as shown in Fig. 11(a). In the example image shown in Fig. 11(a), the black and white interval becomes narrower toward the top.

[0083] Next, the arithmetic processing unit 36 ​​divides the obtained single captured image into a plurality of regions, as shown in Fig. 11(b). Note that, although Fig. 11(b) shows a state in which the image is divided into six regions, the number of divisions is not limited to six, and any number of divisions may be used. As shown in Fig. 11(b), the arithmetic processing unit 36 ​​calculates the spatial frequency of the projection pattern for each divided region to generate an auxiliary image. The number of auxiliary images generated is equal to the number of divided regions.

[0084] The calculation processing unit 36 ​​then analyzes each divided area from the captured image and auxiliary image, making it possible to perform measurements without damaging the inspection area even when the inspection object 50 is a mirror-like body with a large curvature.

[0085] Finally, the above-described embodiments are presented as examples and are not intended to limit the scope of the present invention. The novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Furthermore, each embodiment and each modification of each embodiment is included in the scope and spirit of the invention, and is included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0086] 1 Inspection system 10 Projection section 20. Photography Department 30 Inspection Equipment 35 Control section 36 Processing unit 50 Inspection object [Prior art documents]

Chartered Documents

[0087] [Patent Document 1] Patent No. 6184289

Claims

1. a control unit that obtains a captured image by capturing an image of an object to be inspected onto which a projection pattern composed of a binary periodic image is projected from a projection unit; an arithmetic processing unit that calculates a surface shape of the inspection object by multiplying the photographed image obtained by the control unit with an auxiliary image having continuous periodic gradations generated based on the photographed image and performing low-pass filter processing on the auxiliary image; An inspection device comprising:

2. the calculation processing unit multiplies the captured image by the auxiliary image having the same spatial frequency as the captured image, and then calculates a phase component from information obtained by performing the low-pass filter process; 2. The inspection apparatus according to claim 1 .

3. The control unit reduces the amount of light in an area close to the inspection object and increases the amount of light emitted in an area far from the inspection object in the projection unit, thereby improving luminance uniformity in the captured image obtained.

3. The inspection apparatus according to claim 1 or 2.

4. The arithmetic processing unit feeds back to the control unit an analysis result obtained by analyzing the contrast of the projection pattern based on the captured image captured by the imaging unit, The control unit adjusts the amount of light emitted by the projection unit based on the fed-back analysis result.

4. The inspection apparatus according to claim 3.

5. the calculation processing unit performs phase analysis using the auxiliary image having a different reference frequency for each region of the captured image; 5. The inspection apparatus according to claim 1, wherein the inspection apparatus comprises:

6. The arithmetic processing unit performs a binarization process on the captured image.

6. The inspection device according to claim 1, wherein the inspection device is a semiconductor laser.

7. a projection unit that projects a projection pattern formed of a binary periodic image onto an object to be inspected; an imaging unit that images reflected light from the inspection object onto which the projection pattern is projected by the projection unit; An inspection device according to any one of claims 1 to 6, An inspection system comprising:

8. The projection unit is an image display device.

8. The inspection system according to claim 7.

9. The optical axis direction of the imaging unit and the projection surface of the projection unit are parallel to each other.

9. The inspection system according to claim 7 or 8.

10. a control step of acquiring a captured image by capturing an image of an object to be inspected onto which a projection pattern composed of a binary periodic image is projected from a projection unit; a calculation processing step of multiplying the photographed image obtained in the control step by an auxiliary image having continuous periodic gradations, which is generated based on the photographed image, and performing a low-pass filter process to calculate a surface shape of the inspection object; A program characterized by causing a computer to execute the above.

Images