Optical inspection method, optical inspection program, processing device, and optical inspection device

Abstract

Embodiments of the present application relate to an optical inspection method, an optical inspection program, a processing device, and an optical inspection device. Provided are an optical inspection method, an optical inspection program, a processing device, and an optical inspection device capable of inspecting a surface state of an object. According to the embodiments, the optical inspection method of the surface state of the object includes: acquiring a color vector of a color corresponding to a wavelength by using optical imaging using a wavelength selection section that selectively passes the wavelength from a surface of the object, in an n-dimensional color coordinate system that is the same as or less than a number of color channels of each pixel of an image sensor; and discriminating the surface state of the object according to a direction of the color vector in the color coordinate system.

Description

[0001] This application is based on Japanese Patent Application No. 2021-149457 (Filing date: September 14, 2021) the content of which is incorporated herein by reference in its entirety. This application is based on Japanese Patent Application No. 2021-149457 (Filing date: September 14, 2021) the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] Embodiments of the present application relate to an optical inspection method, an optical inspection program, a processing device, and an optical inspection device. BACKGROUND

[0003] For example, a surface of an object to be inspected is photographed by a general camera, and based on an image of the surface of the object to be inspected photographed, an inspection of a surface state of the object to be inspected is performed. SUMMARY

[0004] An object of the present application is to provide an optical inspection method, an optical inspection program, a processing device, and an optical inspection device capable of inspecting a surface state of an object to be inspected.

[0005] According to the embodiments, the optical inspection method of the surface state of the object to be inspected includes: acquiring a color vector of a color corresponding to a wavelength by using optical imaging using a wavelength selection section that selectively passes a plurality of wavelengths different from each other from a surface of an object to be inspected in an n-dimensional (n is a natural number of 1 or more) color coordinate system of the same number as or less than a number of a plurality of color channels of each pixel of an image sensor; and discriminating the surface state of the object to be inspected based on a direction of the color vector in the color coordinate system.

[0006] According to the above-described optical inspection method of the surface state of the object to be inspected, the surface state of the object to be inspected S can be well inspected. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a block diagram showing an outline of an optical inspection system related to the first to third embodiments.

[0008] Figure 2 is a schematic diagram showing a part of an optical inspection device of the optical inspection system related to the first and second embodiments.

[0009] Figure 3 is a schematic diagram showing Figure 2 is a schematic diagram showing a color filter of a camera of the optical inspection device shown.

[0010] Figure 4 is a schematic diagram showing a camera in which an imaging optical system is omitted and showing a transmission state of light from the color filter to the image sensor when a surface state of an object to be inspected is a standard surface.

[0011] Figure 5 is a schematic diagram showing color vectors of a color coordinate system calculated from an image when the surface state of an object is the standard surface shown in Figure 4

[0012] Figure 6 is a schematic diagram showing a camera omitting an illustration of an imaging optical system and showing a transmission state of light from a color filter to an image sensor when the surface state of an object is a surface having a detected portion on a standard surface.

[0013] Figure 7 is a schematic diagram showing color vectors of a color coordinate system calculated from an image when the surface state of an object is the standard surface shown in Figure 6

[0014] Figure 8 is a flowchart showing a process of obtaining an inspection result of a surface state of an object using an optical inspection device of the optical inspection system according to the first to third embodiments.

[0015] Figure 9 is RGB image data obtained by arranging a paper having a matte surface (left) and a paper having a glossy surface (right) as an object and taking an image using a general camera (RGB camera).

[0016] Figure 10 is RGB image data obtained by taking an image of an object shown in Figure 9 using a camera of an optical inspection device of the optical inspection system according to the second embodiment.

[0017] Figure 11 is a schematic diagram showing color vectors of a color coordinate system calculated from an image when the surface state of an object is the standard surface shown in Figure 9 and Figure 10 is a schematic diagram showing color vectors of a color coordinate system calculated from an image when the surface state of an object is the standard surface shown in

[0018] Figure 12 is a schematic diagram showing a camera of an optical inspection device of the optical inspection system according to the third embodiment.

[0019] Figure 13 is a schematic diagram showing a camera of an optical inspection device of the optical inspection system according to the third embodiment. Figure 12 ​​Schematic cross-sectional view of the camera of the optical inspection device of the optical inspection system shown.

[0020] Figure 14 is a view showing a standard surface observed in the 2nd surface including the optical axis Figure 12 Schematic cross-sectional view of the camera of the optical inspection device of the optical inspection system shown.

[0021] Figure 15 is a schematic view showing the camera of the optical inspection device of the optical inspection system according to the 4th embodiment.

[0022] Figure 16 is a view showing a color vector calculated from the image of the standard surface shown and a color vector calculated from the image of the inspection target when the pixel value IR of the R light is taken for the horizontal axis and the pixel value IB of the B light is taken for the vertical axis according to the surface state of the inspection target Figure 15 Schematic view of the color vector calculated from the image of the standard surface shown and the color vector calculated from the image of the inspection target.

[0023] (Symbol explanation)

[0024] 2: optical inspection system; 4: optical inspection device; 6: display; 12: optical device; 13: camera; 14: image sensor; 14a: light receiving section; 16: light source; 18: beam splitter; 20: processing device; 22: processor; 24: storage section; 24a: optical inspection program; 24b: reference vector data; 26: ROM; 28: RAM; 32: imaging optical system; 34: color filter; 42: 1st wavelength selection filter; 44: 2nd wavelength selection filter; 46: light blocking section. DETAILED DESCRIPTION

[0025] (1st embodiment)

[0026] According to Figures 1 to 8 The optical inspection system 2 according to the present embodiment will be described.

[0027] Figure 1 is a block diagram showing one example of the structure of the optical inspection system 2 according to the present embodiment. As shown in Figure 1 The optical inspection system 2 includes an optical inspection device 4 and a display 6.

[0028] The optical inspection device 4 includes an optical device 12, an image sensor (photographing section) 14, a light source 16, a beam splitter 18, and a processing device 20.

[0029] As shown in Figure 2 The optical device 12 includes an imaging optical system (imaging lens) 32 and a color filter (wavelength selection section) 34.

[0030] The imaging optical system 32 is formed by combining one or more lenses. The imaging optical system 32 can be a single lens, a group of lenses, a refractive index gradient lens, a diffraction lens, a light-guiding lens, a reflective mirror, etc.; it can be any type as long as it images light. Here, light is a form of electromagnetic wave. Electromagnetic waves include, for example, X-rays, ultraviolet light, visible light, infrared light, far-infrared light, millimeter waves, terahertz waves, microwaves, etc. In this embodiment, light is defined as visible light, specifically in the region with wavelengths from 400 nm to 760 nm.

[0031] The imaging optical system 32 images light from the object being inspected. In this embodiment, the color filter 34 is arranged rotationally symmetrically with respect to the optical axis of the imaging optical system 32 at a focal plane at a distance f from the imaging optical system 32. The optical axis C of the imaging optical system 32 coincides with the optical axis (central axis) of the color filter 34. However, the color filter 34 does not necessarily have to be placed at the focal plane; it can be disposed within or outside the imaging optical system 32, or in front, behind, or inside the imaging optical system 32. By arranging the color filter 34 at the focal plane of the imaging optical system 32 as in this embodiment, the relationship between color and direction can be kept constant across the entire surface of the captured image.

[0032] like Figure 3 As shown, in this embodiment, the color filter 34 has a first wavelength selective filter (wavelength selective region) 42, a second wavelength selective filter (wavelength selective region) 44, and a light blocking portion 46 arranged radially outward from the center. The first wavelength selective filter 42, the second wavelength selective filter 44, and the light blocking portion 46 are formed concentrically. However, the wavelength selective region is not limited to this and can be of any shape. That is, the color filter 34 may have at least two different wavelength selective regions. Here, the light blocking portion 46 can be considered as a wavelength selective region that blocks the wavelength range of visible light.

[0033] The first wavelength selective filter 42 is formed in a disk shape. The first wavelength selective filter 42 is disposed on the optical axis C of the imaging optical system 32. The first wavelength selective filter 42 allows light of a first wavelength from the object S after passing through the imaging optical system 32 to pass through. The first wavelength is set within the first wavelength range. Furthermore, the first wavelength selective filter 42 has the property of blocking light of a range different from the first wavelength range from being transmitted.

[0034] The second wavelength selection filter 44 is formed in a circular ring shape outside the first wavelength selection filter 42. The second wavelength selection filter 44 transmits light of a second wavelength different from the first wavelength from the object S after passing through the imaging optical system 32. The width in the radial direction of the second wavelength selection filter 44 can be appropriately set. The second wavelength is set to a second wavelength range. Further, the second wavelength selection filter 44 has a property of blocking light of a wavelength different from the second wavelength range without transmitting the light.

[0035] Therefore, the wavelength selection filters 42, 44 of the color filter 34 have a property of transmitting light of a specific wavelength (or wavelength range; wavelength spectrum) in each of the wavelength selection filters 42, 44 and blocking light of a wavelength deviating from the specific wavelength range. Further, the first wavelength and the second wavelength are respectively included in appropriate ranges, that is, in a first wavelength range and a second wavelength range, but it is preferable that the wavelengths do not overlap each other. Therefore, in the present embodiment, the first wavelength range and the second wavelength range are respectively independent.

[0036] The light blocking portion 46 is formed outside the second wavelength selection filter 44. The light blocking portion 46 is formed of, for example, a black plate, and holds the second wavelength selection filter 44. The light blocking portion 46 blocks light of all wavelengths in the visible light range incident to the imaging optical system 32. The width in the radial direction of the light blocking portion 46 can be appropriately set. In Figure 3 In the present embodiment, the light blocking portion 46 is shown as an example of a circular ring shape, but the outer edge can be an arbitrary shape such as a rectangular shape, as long as the second wavelength selection filter 44 can be held.

[0037] The radius of the outer periphery of the first wavelength selection filter 42 of the color filter 34 is set to r1, and the radius of the outer periphery of the second wavelength selection filter 44 is set to r2. At this time, r2>r1. Here, a region inside the radius r1 of the first wavelength selection filter 42 is set to Al. A region between the outer periphery of the first wavelength selection filter 42 and the outer periphery of the second wavelength selection filter 44 is set to A2. The radius r1 of the first wavelength selection filter 42 and the distance between the outer periphery of the first wavelength selection filter 42 and the outer periphery of the second wavelength selection filter 44, that is, r2-r1 can be appropriately set. More specifically, the radius r1 of the first wavelength selection filter 42 and the radius r2 of the second wavelength selection filter 44 of the color filter 34 can be changed. Therefore, the shape and size of the regions Al, A2 can be changed.

[0038] Further, as one example, the radius r1 of the color filter 34 is about 1.5 mm, and the radius r2 is about 12 mm.

[0039] The image sensor 14 is disposed on an optical path of light that has passed through the imaging optical system 32 and the color filter 34. The image sensor 14 has a light-receiving portion (light-receiving surface) 14a that is an imaging surface at a distance L (> f) from the imaging optical system 32. The optical device 12 and the image sensor 14 constitute a so-called camera (imaging portion) 13.

[0040] As the image sensor 14, a shooting element such as a CCD or a CMOS can be used. The image sensor 14 has a plurality of pixels. The image sensor 14 has a plurality of color channels that spectrally separate at least two mutually different wavelengths in each pixel. Typically, the image sensor 14 has an R channel, a G channel, and a B channel in each pixel. Thus, the image sensor 14 can acquire a color image, and can spectrally separate three mutually different wavelengths.

[0041] Each pixel of the image sensor 14 can also recognize one color, and different colors are recognized by different pixels. In this case, at least two pixels corresponding to different colors are regarded as a group of pixels. The pixels of the group are simply referred to as pixels.

[0042] The light source 16 is used for illumination of the surface of the object S. As the light source 16, an LED can be used, for example. Between the object S and the imaging optical system 32, a beam splitter 18 is disposed. As the beam splitter 18, a half mirror can be used, for example.

[0043] Light from the light source 16 is reflected toward the object S when it is incident on the beam splitter 18, and illuminates the surface of the object S. Part of the light from the surface of the object S is transmitted through the beam splitter 18, and is incident on the image sensor 14 through the imaging optical system 32 and the color filter 34.

[0044] In the present embodiment, for simplicity of explanation, in the color filter 34, each of the wavelength-selective filters 42, 44 is configured to transmit light in a certain wavelength range in visible light, and to block (prevent transmission of) wavelengths that deviate from the certain wavelength range, for example.

[0045] Here, the first wavelength is set to blue (B) light, and the second wavelength is set to red (R) light. In the present embodiment, for convenience, the wavelength of red (R) light is set to 700 nm, and the wavelength of blue (B) light is set to 435 nm in accordance with a decision of the Commission Internationale de I’Eclairage (CIE).

[0046] In the present embodiment, the region Al of the first wavelength selection filter 42 passes, for example, blue light (435 nm) among visible light and B light having a first wavelength (for example, 400 nm to 500 nm) around the same, and blocks light of wavelengths other than the same. In the present embodiment, the region A2 of the second wavelength selection filter 44 passes, for example, red light (700 nm) among visible light and R light having a second wavelength (for example, 600 nm to 700 nm) around the same, and blocks light of wavelengths other than the same. Further, the range of the first wavelength that passes through the region Al of the first wavelength selection filter 42 and the range of the second wavelength that passes through the region A2 of the second wavelength selection filter 44 are preferably not overlapped in the present embodiment. Thus, the first wavelength selection region blocks light of the second wavelength and wavelengths around the same without passing the same. The second wavelength selection region blocks light of the first wavelength and wavelengths around the same without passing the same.

[0047] Further, the wavelength of green (G) light defined by the International Commission on Illumination is 546 nm, which is a wavelength between R light and B light. Thus, the wavelengths of R light and B light are less likely to overlap than in the case of using the wavelengths of R light and G light, or in the case of using the wavelengths of G light and B light.

[0048] As the processing device 20, a general-purpose computer is used, for example. The processing device 20 is provided with, for example, a processor 22, a storage 24, a ROM (Read Only Memory) 26, and a RAM (Random Access Memory) 28.

[0049] The processing device 20 can also be able to communicate with the image sensor 14 in a wired or wireless manner. The processing device 20 can also be included in the camera 13, for example.

[0050] The processor 22 is connected to the image sensor 14 and the storage 24. The processor 22, the ROM 26, and the RAM 28 are connected via a bus, for example. These storage 24, ROM 26, and RAM 28 can communicate with each other and the processor 22.

[0051] Further, the processing device 20 can also be located outside the optical inspection device 4. In this case, the output of the image sensor 14 can be output to the outside of the optical inspection device 4, or recorded to a storage on the cloud. That is, the calculation of information related to the object S can be performed inside the optical inspection device 4, or outside.

[0052] The processor 22 includes, for example, a central processing unit (CPU), a GPU, an application specific integrated circuit (ASIC), or the like. The processor 22 is not limited to the case where it is provided as a dedicated circuit, but can be provided as a program executed by a computer. In this case, the program is recorded in a storage region or the like in an integrated circuit, a storage, or the like.

[0053] The processor 22 can also be located in a server in a cloud service that transmits and receives data via a network.

[0054] The processor 22 has a function as an image processing section for image data (RGB image data Irgb, R image data Ir, G image data Ig, and B image data Ib) captured by the image sensor 14. The processor 22 calculates information related to the subject S on the basis of the output of the image sensor 14. In addition, the image data acquired by the image sensor 14 is output from at least two or more pixels.

[0055] For example, various programs are stored in the storage 24. The processor 22 functions in accordance with the programs by writing the various programs stored in the storage 24 to the RAM 28 and executing them, for example.

[0056] The various programs do not necessarily have to be stored in the storage 24, and the processor 22 can also cause the various programs to be executed on a server via a network.

[0057] The storage 24 is, for example, a nonvolatile memory such as an HDD, an SSD, or a flash memory, but can also have a volatile memory. The storage 24 can also use a cloud memory, for example. In the storage 24, for example, an optical inspection program (algorithm) 24a related to the present embodiment and a plurality of reference vector data 24b that are different from each other in correspondence with settings of the camera 13 (settings of the color filter 34 with respect to the optical axis C) are stored. The optical inspection program 24a can also be stored in the ROM 26.

[0058] The optical inspection program 24a can be pre-installed to the optical inspection device 4, can be stored in a nonvolatile storage medium, or can also be distributed via a network. The optical inspection program 24a can also be located outside the optical inspection device 4, such as an appropriate server or the like.

[0059] In the present embodiment, the optical inspection program 24a causes the computer to execute: calculation of a color vector Cn (n represents a dimension) from image data (pixel value) of each pixel acquired in all or a predetermined range of the light-receiving portion 14a of the image sensor 14, comparison with, for example, reference vector data 24b stored in the storage portion 24, and calculation of the surface state of the object S.

[0060] For example, in the storage portion 24, the relationship of the optical axis C of the imaging optical system 32 and the color filter 34 is stored. The relationship of the optical axis C of the imaging optical system 32 and the color filter 34 includes, for example, the transmission wavelength, the shielding wavelength, and the arrangement of the first wavelength selection filter 42, the second wavelength selection filter 44, and the light ray shielding portion 46 of the color filter 34. In addition, the optical inspection program 24a can acquire the relationship of the optical axis C of the imaging optical system 32 and the color filter 34 by a program including acquisition of information of the optical device 12 and / or the camera 13.

[0061] In addition, for example, the processor 22 is connected to the display 6. The display 6 displays various information based on the processing of the processor 22. The display 6 displays, for example, an image captured by the image sensor 14, and displays a determination result of the surface state of the object S described later.

[0062] In addition, the surface state of the object S includes a planar state of a face in all or a predetermined range of the surface of the object S, the presence or absence of a defect or a rough face of a region to be inspected, and the like, a surface roughness (roughness sense) / gloss sense (refer to the second embodiment), and other various states, which are detected and judged by the processing device 20.

[0063] Next, the operation of the optical inspection system 2 according to the present embodiment will be described.

[0064] In the case of inspecting the surface of the object S, the processor 22 of the processing device 20 captures the surface of the object S by the camera 13 in a state where the surface of the object S is illuminated by illumination light from the light source 16.

[0065] The imaging optical system 32 images a point on an object. The first object point Ol is taken in the standard surface Sl of the surface of the object S, and the second object point O2 is taken in the detected portion S2. Light incident to the first object point Ol is reflected as first reflected light. Light incident to the second object point O2 is reflected as second reflected light. Light from the first object point Ol is moved to the first image point by the imaging optical system 32. Light from the second object point O2 is moved to the second image point by the imaging optical system 32. It is assumed that the first image point and the second image point are located on the image sensor 14.

[0066] The first object point O1 is located on the mirror-like standard surface S1, so the specular reflection component (normal reflection component) of light increases. That is, the light distribution from the first object point O1 is as follows: Figure 4 The light distribution shown tends to be narrow. Since the second object point O2 is not on the mirror surface but on, for example, a rough surface, the diffuse component of the light increases. That is, the light distribution from the second object point O2 is as follows: Figure 6 The diagram shows a wide angular distribution.

[0067] like Figure 2 As shown, for example, illumination light from light source 16 is reflected by beam splitter 18 to illuminate the surface of the object under test S. On the surface of the object under test S, light rays (specular reflection component) L11 reflected orthogonally at a certain point O of the object under test S and light rays L21 and L31 scattered at appropriate angles are refracted by imaging optical system 32 and incident on color filter 34.

[0068] Figure 3 In the embodiment shown, region A1 of the first wavelength selective filter 42 of the color filter 34 of the camera 13 allows light B from the object S to pass through, but blocks light R and G. The light B passing through region A1 on the optical axis C of the imaging optical system 32 is the orthogonal reflected light component from the surface of the object S. Region A2 of the second wavelength selective filter 44 allows light R from the object S to pass through, but blocks light G and B. The light R passing through region A2, which is off the optical axis C of the imaging optical system 32, is the scattered light component from the surface of the object S. Furthermore, light incident on region A3 of the light blocking portion 46 is blocked.

[0069] In the optical device 12 of this embodiment, blue (B) light emitted from any point O of the object S, whose principal ray is parallel to the optical axis C when incident on the imaging optical system 32 and the color filter 34, is separated into blue light. That is, the optical device 12 of this embodiment is a telecentric optical system with respect to blue light. On the other hand, the optical device 12 of this embodiment is a non-telecentric optical system without respect to red (R) light.

[0070] Therefore, the component that is primarily reflected by orthogonal reflection is the B-beam incident on the image sensor 14 and captured by the image sensor 14 as B-image data (first image data) Ib. Furthermore, the orthogonal reflection component is not only completely parallel to the optical axis C, but also allows for appropriate offset. In this embodiment, when the direction along the optical axis C is set to 0, the orthogonal reflection component becomes... Figure 2 The range 0 ≤ θb is shown. Furthermore, the angle θb can be appropriately set. This angle θb depends on the distance between the imaging optical system 32 and the color filter 34, the radius r1 of region A1 of the first wavelength selective filter 42 of the color filter 34, etc.

[0071] The region A2 of the 2nd wavelength selection filter 44 of the color filter 34 of the camera 13 passes R light of a 1st scattering angle θr (θb≤θg<θs) with respect to the optical axis C, but blocks B light of a normal reflection light component and light of a 2nd scattering angle θs (θs≤θ). Therefore, only a component of the 1st scattering angle θr is incident on the image sensor 14 as R image data (2nd image data) Ir and is captured by the image sensor 14 as an R image. The angle θr depends on the distance of the imaging optical system 32 from the color filter 34, the size of the region A2 of the 2nd wavelength selection filter 44 of the color filter 34, and the like.

[0072] The angle θs depends on the distance of the imaging optical system 32 from the color filter 34, the size of the region A3 of the light blocking portion 46 of the color filter 34, and the like.

[0073] Therefore, with respect to the RGB image data Irgb, the R image data Ir, the (G image data Ig, ), and the B image data Ib captured by the image sensor 14, colors are added in accordance with the scattering angle (including normal reflection light) from the surface of the object S. Therefore, the color of the obtained RGB image data Irgb does not depend on the color of the surface of the object S itself, but depends on the wavelength selectively passed in accordance with the setting of the color filter 34. Therefore, with respect to the RGB image data Irgb obtained by the camera 13 according to the present embodiment, by appropriately setting the color filter 34, even with respect to images of the same surface of the object S, it can be considered that the colors are different from those of an image of a general camera not using the color filter 34.

[0074] In the present embodiment, R light and B light are incident on the light receiving portion 14a of the image sensor 14, but G light is blocked by the color filter 34 and is not incident on the light receiving portion 14a of the image sensor 14. Therefore, in each pixel of the light receiving portion 14a, light is received with an appropriate pixel value (for example, 256 gradations from 0 to 255) in the R channel and the B channel, but light is not received in the G channel.

[0075] Here, a 3-dimensional (orthogonal) coordinate system in which the pixel values of R light, G light, and B light are outputs is taken as a color coordinate system (color space). In the present embodiment, however, the G channel is set to not receive light in accordance with the color filter 34. Therefore, the output of G light can be ignored. Therefore, in the present embodiment, a 2-dimensional (orthogonal) coordinate system in which the pixel values of R light and B light are outputs is taken as a color coordinate system.

[0076] Figure 4 The positional relationship between the camera 13, in which the imaging optical system 32 is omitted, and the surface of the object S is shown. Figure 4The surface of the object S shown is a plane (hereinafter referred to as a standard surface S1) that is parallel to the optical axis C and is, for example, a mirror surface that is not damaged.

[0077] The light from the standard surface S1 among the light incident on the image sensor 14 through the color filter 34 of the camera 13 is based on the B light on the optical axis C (on the region Al) through the color filter 34. Therefore, the image sensor 14 obtains a blue-colored image of the regular reflection light from the standard surface S1 in the B image data Ib. Figure 4 The B image data Ib of the standard surface S1 of the object S shown is obtained as a blue-colored image in its entirety.

[0078] The light from the position equivalent to the standard surface S1 does not substantially incident on the image sensor 14 as R light, or even if it is incident, the intensity is small to the extent that the pixel value can be ignored. Therefore, the image of the standard surface S1 in the R image data Ir becomes black.

[0079] In addition, in the present embodiment, the G light from the surface of the object S among the light incident on the image sensor 14 through the color filter 34 does not incident, or even if it is incident, the intensity is small to the extent that the pixel value can be ignored. Therefore, the G image data Ig becomes black in its entirety.

[0080] Therefore, the RGB image data Irgb obtained by the optical inspection device 4 related to the present embodiment is attached with colors corresponding to the direction information of the light based on the color filter 34. The R image data Ir, the G image data Ig, and the B image data Ib obtained by separating the RGB image data Irgb into each color channel respectively become images based on the surface information (unevenness information) of the object S. In this way, the optical inspection device 4 related to the present embodiment acquires the structure (unevenness) information of the object S from the image captured by the image sensor 14.

[0081] In Figure 5 , a 2-dimensional color coordinate system is set in which the pixel value IR of the R light is taken on the horizontal axis and the pixel value IB of the B light is taken on the vertical axis. The processing device 20 images the surface of the object S by the camera 13, and the processing device 20 plots the pixel values IR and IB of the R light and the B light acquired by each pixel of the entire or a predetermined range of the light receiving portion 14a of the image sensor 14 as Figure 5 the graph of the color coordinate system shown.

[0082] For example, in the graph of the color coordinate system, a vector display is performed as shown by a symbol C2 in Figure 5 . In the present embodiment, it is referred to as a color vector Cn (n is the dimension number).

[0083] In the present embodiment, each pixel of the light-receiving portion 14a of the image sensor 14 has, for example, three different color channels of R (red), G (green), and B (blue). According to the structure of the color filter 34, G light is not accepted in the light-receiving portion 14a of the image sensor 14. Therefore, the color vector Cn can be expressed as C2 in two dimensions of R light and B light.

[0084] The color vector C2 is a vector having the pixel value IR of each R channel and the pixel value IB of each B channel as constituent elements. That is, the color vector C2 can be expressed by the following equation.

[0085] C2 = (IR, IB)

[0086] The color vector C2 = (IR, IB) corresponding to each object point Ol, O2 is calculated by the processing device 20.

[0087] In the image of the standard surface Sl of the object S shown in FIG. 9, the B image data Ib is obtained as an image of blue, but the R image data Ir becomes an image of black. That is, in the color vector C2 corresponding to the first object point Ol, the blue intensity component (IB) is large. Therefore, the color vector C2 extends from the origin along the vertical axis IB. Figure 4 Figure 5 The color vector C2 shown in FIG. 10 extends from the origin along the vertical axis IB.

[0088] Further, the magnitude of the pixel values IR, IB in each pixel mainly depends on the intensity of the illumination light, the distance between the camera and the surface of the object S, and the like. In addition, it also depends on the relationship between the color of the surface of the object S and the color filter 34, and the like.

[0089] Figure 6 The positional relationship between the camera 13, which is shown in FIG. 11 omitting the illustration of the imaging optical system 32, and the surface of the object S is shown. In the camera 13, the color filter 34 is disposed on the image sensor 14. Figure 6 In the surface of the object S shown in FIG. 12, there is a foreign matter or a damage or the like, which is a detected portion (defect) S2, in a part of the standard surface Sl. Here, the detected portion S2 means a defect to be detected. That is, the detected portion S2 is a defect.

[0090] The light ray from the standard surface Sl among the light incident on the image sensor 14 through the color filter 34 of the camera 13 is based on B light on the optical axis C (on the region Al) through the color filter 34. Therefore, the image sensor 14 obtains the regular reflection light from the standard surface Sl as an image of blue in the B image data Ib. The light from the position corresponding to the detected portion S2 is incident on the image sensor 14 as B light and R light. Therefore, the image of the standard surface Sl of the object S in the B image data Ib is blue, and the image of the detected portion S2 becomes blue and red.

[0091] ​Most of the detected portion S2 is not a region parallel to the standard surface S1, for example. Alternatively, the size of the detected portion S2 is close to or smaller than the wavelength of visible light, so scattering caused by a diffraction phenomenon of light occurs. For example, it is known that a rough surface having a concave-convex shape close to the wavelength of light scatters the light. Most of the light from the detected portion S2 in the light incident on the image sensor 14 through the color filter 34 is incident on the imaging optical system 32 as scattered light. Therefore, the light from the detected portion S2 is incident on the image sensor 14 through the region Al of the color filter 34 and the region A2 outside the region Al. That is, a part of the light from the detected portion S2 in the light incident on the image sensor 14 through the color filter 34 is based on the R light passing through the region A2 that deviates from the optical axis C of the color filter 34. Therefore, the image sensor 14 obtains the scattered light from the detected portion S2 as a red image in the R image data Ir. The light from a position corresponding to the standard surface S1 is not incident on the image sensor 14 as R light. Therefore, the image of the standard surface S1 in the R image data Ir becomes black, and the image of the detected portion S2 becomes red. On the other hand, the image of the standard surface S1 in the B image data Ib becomes blue, and the image of the detected portion S2 also becomes blue.

[0092] In addition, in the present embodiment, the G light from the surface of the object S in the light incident on the image sensor 14 through the color filter 34 is not incident. Therefore, the G image data Ig as a whole becomes black.

[0093] Therefore, the RGB image data Irgb obtained by the optical inspection device 4 according to the present embodiment is attached with colors corresponding to the direction information of the light based on the color filter 34. The R image data Ir, the G image data Ig, and the B image data Ib obtained by separating the RGB image data Irgb into each color channel become images based on the surface information (concave-convex information) of the object S, respectively. In this way, the optical inspection device 4 according to the present embodiment acquires the structure (concave-convex) information of the object S by the image captured by the image sensor 14.

[0094] In Figure 7 , the same as Figure 5 , a 2-dimensional color coordinate system in which the pixel value IR of the R light is taken on the horizontal axis and the pixel value IB of the B light is taken on the vertical axis is set. The processing device 20 images the surface of the object S by the camera 13, and the processing device 20 plots the pixel values IR and IB of the R light and the B light acquired by each pixel of the entire or a predetermined range of the light receiving portion 14a of the image sensor 14 as a graph of the color coordinate system as shown in FIG. 9. For example, in the graph of the color coordinate system, as in FIG. 9, the pixel value IR of the R light and the pixel value IB of the B light of the standard surface S1 are plotted as a point P1 on the color coordinate system. The pixel value IR of the R light and the pixel value IB of the B light of the detected portion S2 are plotted as a point P2 on the color coordinate system. Figure 7 Figure 7 ​The vector is displayed as shown by a symbol C2. The color vector C2 corresponding to the second object point O2 has components of both a blue intensity component (IB) and a red intensity component (IR).

[0095] Therefore, according to the surface state of the object S, Figure 5 the direction of the color vector C2 shown changes. Thus, the color vector C2 greatly differs in direction according to the presence / absence of the minute defect. That is, by the direction of the color vector C2, it is possible to recognize the presence / absence of the minute defect of each object point. Figure 7 the direction of the color vector C2 shown changes. Thus, the color vector C2 greatly differs in direction according to the presence / absence of the minute defect. That is, by the direction of the color vector C2, it is possible to recognize the presence / absence of the minute defect of each object point.

[0096] For example, it is assumed that Figure 4 The standard surface S1 of the object S shown is a required product state (surface state). Then, the standard surface S1 of the object S shown is imaged, and when the processing device 20 outputs the color vector C2 corresponding to the standard surface S1, the color vector C2 is set as a reference vector. This reference vector is stored as one of the reference vector data 24b in the storage section 24 in correspondence with the structure of the color filter 34, that is, the structure of the camera 13, for example. Figure 4 Figure 4 The standard surface S1 of the object S shown is a required product state (surface state). Then, the standard surface S1 of the object S shown is imaged, and when the processing device 20 outputs the color vector C2 corresponding to the standard surface S1, the color vector C2 is set as a reference vector. This reference vector is stored as one of the reference vector data 24b in the storage section 24 in correspondence with the structure of the color filter 34, that is, the structure of the camera 13, for example.

[0097] Then, the surface of the object S shown including the standard surface S1 and the detected portion S2 is imaged, and when the processing device 20 outputs the color vector C2, the processing device 20 compares the direction of the reference vector stored in the storage section 24 and the color vector C2. The processing device 20 can judge (output) whether or not the surface of the object S is within the range of the required product state according to whether or not the direction of the reference vector and the color vector C2 is identical or different. Figure 6

[0098] Further, the processing device 20 can not determine the direction of the reference vector shown as one direction, but set a threshold value (allowable range) allowing the shift of the direction of the reference vector. The threshold value is stored as a part of the reference vector data 24b of the storage section 24 together with the reference vector, for example. At this time, the processing device 20 refers to the reference vector stored in the storage section 24 and refers to the threshold value, and can judge (output) whether or not the surface of the object S is within the range of the required product state according to whether or not the direction of the color vector C2 with respect to the reference vector is within the range of the threshold value or outside the range of the threshold value. Figure 5

[0099] This series of processes of checking the surface state of the object S by the processing device 20 is executed according to the flowchart shown using the program 24a stored in the storage section 24, for example. Figure 8

[0100] ​​​​The reference vector data 24b including the threshold is stored in advance in, for example, the storage section 24. In addition, the relationship of the color filter 34 to the wavelength accepted by the image sensor 14, that is, the structure of the camera 13 is stored in, for example, the storage section 24. Further, the camera 13 can also hold its own structure data, and upon connection to the processing device 20, by communication with the processor 22 of the processing device 20, the processor 22 recognizes the structure of the camera 13. In this case, the structure of the camera 13 does not necessarily have to be stored in advance in the storage section 24. The threshold can be appropriately changed by setting.

[0101] The processor 22, when inspecting the surface state of the object S, acquires the relationship of the color filter 34 to the wavelength accepted by the image sensor 14, and acquires an image using the image sensor 14 of the camera 13 (step ST1). At this time, the processor 22 causes the image acquired by the image sensor 14 of the camera 13 to be displayed on the display 6.

[0102] The surface of the object S is, for example, in the state shown in FIG. 1. Figure 6 Figure 6 Most of the surface of the object S in the example shown in FIG. 1 is a standard surface SI on which light incident through the color filter 34 is incident as regular reflection light, but a detection portion S2 is formed in a part thereof.

[0103] The processor 22 calculates the color vector of each of the pixels in each pixel based on the output grayscale (pixel value) of the color channel (in this case, 2 of the R channel and the B channel) of each pixel of the entire range or a predetermined range of the light receiving section 14a of the image sensor 14 (step ST2). Further, the processing device 20 determines the maximum dimension of the color coordinate system based on the acquisition of the relationship of the color filter 34 to the color of the image obtained by the image sensor 14. In the present embodiment, the colors that can be acquired by the image sensor 14 are 3 colors of R, G, and B, but the transmission wavelength of the color filter 34 is 2 of R and B, so the color coordinate system becomes 2-dimensional.

[0104] As described above, the imaging optical system 32 images a point on the object. The processor 22 calculates the color vector C2 in each pixel (step ST3). That is, the processor 22 calculates the direction (angle or slope) of the color vector C2.

[0105] The processor 22 compares the color vector C2 acquired and calculated from each pixel with the reference vector of the reference vector data 24b, respectively (step ST4). That is, the direction (angle or slope) of the color vector is collated with the direction (angle or slope) of the reference vector that is the same as or closest to the color vector C2 from the reference vector data 24b.

[0106] ​Processor 22 outputs the surface condition of the inspected object S as an inspection judgment result based on whether the color vector C2 is within the threshold of the reference vector (step ST5). At this time, processor 22, for example, causes display 6 to show the judgment result. Figure 5 As shown, let the direction of the color vector calculated from each pixel be, for example, considering the threshold, and be parallel to... Figure 5 The reference vectors shown are consistent. At this time, the processing device 20, for example, causes the display 6 to show that the surface of the inspected object S is normal, as a judgment result. Figure 7 As shown, let's assume that a portion of the direction of the color vector calculated from each pixel is deviated from, for example, considering a threshold. Figure 5 The reference vector is shown. At this time, the processing device 20, for example, causes the display 6 to show the presence of the detected part S2 as a determination result. In addition, the processing device 20 can also make people around the optical inspection system 2 recognize the determination result by sound. Furthermore, the inspection determination signal of the inspected object S in the processing device 20 is preferably also used as an operation trigger signal for a device that operates in a way that separates the inspected object S having the detected part S2 from the inspected object S determined to not have the detected part S2.

[0107] As described above, the processing device 20 determines the surface condition (no defects / defects) of the inspected object S.

[0108] The optical inspection procedure 24a can be performed automatically through steps ST1-ST5, or, for example, by user confirmation between steps ST1 and ST2. If user confirmation is performed in step ST1, the inspection area in the image can be appropriately set. Then, in steps ST2-ST5, the surface condition of the inspected object S within the set inspection area can be determined. The setting of the inspection area can also be maintained at a predetermined state.

[0109] In this embodiment, an example is described whereby the color vector C2 calculated by the processor 22 based on the output of each pixel is compared with the reference vector of the reference vector data 24b in step ST4. However, for example, if the intensity of the illumination light and the reflection intensity from the object under inspection S are known in advance, defects can also be detected by comparing only the intensity of the B light. Alternatively, for example, the color filter 34 can transmit only the B light, as... Figure 5In the case where the B light is accepted by the image sensor 14 and the G light and the R light are not accepted, the output of the pixel value of the B channel of each pixel acquired by the image sensor 14 is obtained, but the outputs of the pixel values of the G channel and the R channel cannot be obtained or are negligibly small compared with the output of the pixel value of the B channel. In this case, the direction of the color vector can be equivalent to the direction along the 1 dimension. Therefore, with respect to the direction of the color vector, in the case where the direction can be equivalent to the direction along the 1 dimension, it is not necessarily necessary to compare the direction of the color vector with the direction of the reference vector. Therefore, the processing device 20 can determine the surface state of the subject S based on the direction of the color vector in the color coordinate system even if it is not necessarily compared with the direction of the reference vector.

[0110] Further, in the present embodiment, an example in which the color vector C2 is calculated for each pixel and each color vector C2 is compared with the reference vector is described. For example, the processor 22 can calculate one color vector C2 based on one image by calculating the average of the pixel values. Also, the processor 22 can compare the color vector C2 calculated by calculating the average of the pixel values with the reference vector.

[0111] Further, the light intensities of the R image data Ir, the G image data Ig, and the B image data Ib acquired by each pixel of the image sensor 14 of the optical inspection device 4 according to the present embodiment complementarily change when the amount of light of the reflected light from the object point on the subject S is considered to be constant. That is, when the light intensity of the R light in a certain pixel among the reflected light rays from the subject S passing through the color filter 34 becomes strong, the light intensity of the B light (and the light intensity of the G light) in the pixel becomes weak. In addition, when the light intensity of the B light in another certain pixel becomes strong, the light intensity of the R light (and the light intensity of the G light) in the pixel becomes weak. This is because the color and the direction of the reflected light correspond, which means that, for example, if the R light becomes more, the reflected light component in the direction corresponding thereto becomes more, and at the same time, the reflected light component in the direction corresponding to the B light or the G light becomes less.

[0112] In contrast, in the R image data, the G image data, and the B image data of the subject S photographed by the general camera without passing through the color filter 34 described in the present embodiment, the light intensity of the R light, the light intensity of the G light, and the light intensity of the B light in a certain pixel variously change depending on the color of the subject, and there is no complementary relationship described above. This is because the color and the direction of the reflected light do not correspond.

[0113] In addition, even if the standard surface S1 in which there is no damage is photographed by the general camera, with respect to the color vector described in the present embodiment, unless it is the case where the standard surface of the subject S reflects only the blue color, it is not calculated in the direction parallel to the axis indicating the B light.

[0114] In contrast, with respect to the color vector C2 described in the present embodiment, regardless of whether or not the surface of the object S reflects only blue light, in the case where the surface state is the standard surface S1, the direction is calculated in the longitudinal axis direction of the B light. Thus, the direction of the color vector C2 of the standard surface S1 according to the present embodiment is not dependent on the color of the object S. In addition, as long as the surface of the object S slightly reflects light other than blue light, that is, as long as red light is reflected, as described above, the defect (detected portion (defect) S2) can be detected using the direction of the color vector C2 without being affected by the color of the object S.

[0115] Thus, according to the optical inspection device 4 according to the present embodiment, the surface state of the object S can be favorably inspected without being dependent on the color of the object S.

[0116] According to the present embodiment, the optical inspection method of the surface of the object S includes: acquiring a color vector of a color corresponding to a wavelength in an n-dimensional (n is a natural number of 1 or more) color coordinate system having the same number of color channels as the number of the plurality of color channels of each pixel of the image sensor 14 or less than the number, by optical imaging using a color filter (wavelength selection portion) 34 that passes the plurality of wavelengths different from each other from the surface of the object S; and discriminating the surface state of the object S based on the direction of the color vector in the color coordinate system.

[0117] According to the present embodiment, the optical inspection method of the surface of the object S preferably includes associating the direction of the color vector in the color coordinate system with the color.

[0118] According to the present embodiment, with respect to the plurality of wavelengths different from each other, the directions of the light from the object S are different from each other.

[0119] According to the present embodiment, in the optical inspection method of the surface of the object S, the discriminating the surface state of the object S preferably includes calculating the closeness of the direction of the color vector to a reference vector that is a reference for the discrimination of the surface state of the object S in each pixel.

[0120] According to the present embodiment, the optical inspection program 24a of the surface of the object S causes a computer to execute: acquiring a color vector of a color corresponding to a wavelength in an n-dimensional (n is a natural number of 1 or more) color coordinate system having the same number of color channels as the number of the plurality of color channels of each pixel of the image sensor 14 or less than the number, by optical imaging using a color filter (wavelength selection portion) 34 that passes the plurality of wavelengths different from each other from the surface of the object S; and discriminating the surface state of the object S based on the direction of the color vector in the color coordinate system.

[0121] Thus, according to the present embodiment, the surface state of the object S can be discriminated from the direction of the color vector of the color coordinate system calculated from the optical imaging of the light from the surface of the object S passing through the color filter 34 that passes a plurality of wavelengths different from each other. The direction of the color vector at this time is not dependent on the color of the object S but on the concave-convex information. Therefore, the optical inspection method, the optical inspection program 24a, the processing device 20, and the optical inspection device 4 according to the present embodiment can each well inspect the surface state of the object S.

[0122] In addition, according to the present embodiment, by setting the reference vector of the predetermined color coordinate system, calculating the color vector of the predetermined color coordinate system from the image captured by the camera 13, and comparing the direction of the calculated color vector with the reference vector, the surface state of the object S can be inspected.

[0123] In the present embodiment, the G light from the surface of the object S is set to be blocked by the color filter 34. By providing a region that passes the G light in the color filter 34, the G light can be received in each pixel of the light-receiving portion 14a of the image sensor 14. In this case, the color coordinate system becomes 3-dimensional. At this time, the reference vector also becomes 3-dimensional. In the present embodiment, the image sensor 14 that can acquire images of the R light, the G light, and the B light, which are three colors, is used, so the color coordinate system is at most 3-dimensional. In the case of using a hyperspectral camera or the like that can separate and acquire N colors (N is a natural number of 4 or more), the color coordinate system becomes at most N-dimensional. That is, by setting the N-dimensional reference vector corresponding to the color filter 34 of the camera 13, the processing device 20 can determine whether the surface of the object S is within the range of the required product state.

[0124] Further, generally, the color vector can be defined with respect to N independent color channels. That is, when the pixel values of the N independent color channels are set to I1, I2, …, IN, the N-dimensional color vector can be expressed by the following expression.

[0125] CN = (I1, I2, …, IN)

[0126] The calculation time of the color vector C2 of the color coordinate system varies depending on the number of pixels within the predetermined range, the processing capacity of the processor 22 of the processing device 20, and the like. When the calculation time is long, the output of the inspection result of the surface state of the object S is delayed. Therefore, as the color coordinate system, the N-dimensional reference vector can be set at most, or the n-dimensional reference vector (2 ≤ n ≤ N (n, N are natural numbers)) that is less than N-dimensional can be set.

[0127] Thus, according to the present embodiment, the optical inspection method, the optical inspection program 24a, the processing device 20, and the optical inspection device 4 that can well inspect the surface state of the object S can be provided.

[0128] In the present embodiment, it is described that the color filter 34 passes blue (B) light and blocks red (R) light as the first wavelength selection filter 42 on the imaging optical system 32 and passes red (R) light and blocks blue (B) light as the second wavelength selection filter 44. In the color filter 34, for example, red (R) light can also be passed and blue (B) light can be blocked as the first wavelength selection filter 42, and blue (B) light can be passed and red (R) light can be blocked as the second wavelength selection filter 44.

[0129] In addition, in the present embodiment, an example in which the color filter 34 uses the first wavelength selection filter 42 and the second wavelength selection filter 44 is described. The color filter 34 can also be configured to continuously change the wavelength of light transmitted, for example, from the inside toward the outside, instead of the first wavelength selection filter 42 and the second wavelength selection filter 44. That is, the color filter 34 can also be configured to pass light of a certain wavelength in a circular ring shape with respect to a common central axis in a circular ring shape of a predetermined radius, but not to pass light of a wavelength different from the certain wavelength at the position of the predetermined radius. For example, the color filter 34 can also be configured to pass blue (B) light at the center, to change the wavelength of light passing through the color filter 34 as it goes outward in the radial direction, and to pass green (G) light at the outermost edge (inside the light blocking portion 46) of the color filter 34.

[0130] In the present embodiment, it is described that the image sensor 14 acquires an RGB image, but can acquire, for example, a color channel of a wavelength corresponding to the wavelength of light transmitted by the color filter 34. That is, the wavelength of light received by the light receiving portion 14a of the image sensor 14 can be selected to be an appropriate wavelength other than R light, G light, and B light.

[0131] (Modified Example)

[0132] Figure 3 The color filter 34 illustrated, for example, can block the position indicated by the symbol 42 on the optical axis C, can use the position indicated by the symbol 44 as a first wavelength selection region that passes, for example, red (R) light as light of a first wavelength, and can use the position indicated by the symbol 46 as a second wavelength selection region that passes, for example, blue (B) light as light of a second wavelength.

[0133] In this case, the image sensor 14 acquires an image of the surface of the subject S using scattered light of a first scattering angle of a first wavelength that has passed through the first wavelength selection region and scattered light of a second scattering angle of a second wavelength that has passed through the second wavelength selection region. In this case, the processing device 20 calculates a color vector based on the scattered light, not based on the direct reflection light component, according to the image acquired by the image sensor 14. The reference vector is set according to such a color filter 34.

[0134] Therefore, the image of the surface of the object S can be obtained by using the optical imaging of the image sensor 14 by the wavelength selection section 34 passing the first wavelength of the light from the surface of the object S by the regular reflection light or the scattered light and the second wavelength different from the first wavelength of the light from the surface of the object S by the scattered light. Further, the color vector is calculated from the pixel value of the first wavelength and the pixel value of the second wavelength in the color coordinate system of at least 2 dimensions which is the same number or less than the number of the plurality of color channels of each pixel of the image sensor 14. The inspection of the surface state of the object S can be performed using such a color vector.

[0135] (2nd Embodiment)

[0136] Using Figures 9 to 11 The 2nd embodiment will be described. The present embodiment is a modification of the 1st embodiment, and the same reference numerals are attached to the same components as those described in the 1st embodiment or components having the same function, and detailed description will be omitted.

[0137] The optical inspection system 2 according to the present embodiment can be used as it is for the optical inspection system 2 described in the 1st embodiment.

[0138] In Figure 9 , the RGB image data photographed by arranging the paper PM having a surface in a matte (mat) state and the paper PG having a surface in a glossy (luster) state and using a general camera (RGB camera) is shown. The paper PM having a surface in a matte (mat) state and the paper PG having a surface in a glossy (luster) state are generally used as a photo paper or the like, respectively.

[0139] In Figure 10 , the RGB image data obtained by photographing the papers PM, PG shown in Figure 9 using the camera 13 of the optical inspection apparatus 4 according to the present embodiment is shown.

[0140] The surface of the paper PM having a surface in a matte (mat) state on the left side and the surface of the paper PG having a surface in a glossy (luster) state on the right side of, for example, Figure 9 , can be acquired as a product of a certain manufacturer, respectively.

[0141] In Figure 11 , a color coordinate system in which the pixel value IR of the R light is taken on the horizontal axis and the pixel value IB of the B light is taken on the vertical axis is set. In Figure 11In the present embodiment, the color vector C2M of the image of the surface of the paper PM having the surface with the desired matte (matte) state and the color vector C2G of the image of the surface of the paper PG having the surface with the desired glossy (gloss) state calculated by the processor 22 of the processing device 20 are shown. The processor 22 of the processing device 20 stores the color vector C2M of the image of the surface of the paper PM having the surface with the desired matte (matte) state as the first reference vector, the color vector C2G of the image of the surface of the paper PG having the surface with the desired glossy (gloss) state as the second reference vector, as the reference vector data 24b to, for example, the storage section 24. That is, with respect to the reference vector data 24b of the present embodiment, two reference vectors are stored.

[0142] Further, the color vector C2G (second reference vector) of the image of the paper PG having the surface with the glossy state as the surface of the object S has a larger slope (angle) than the color vector C2M (first reference vector) of the image of the paper PM having the surface with the matte state as the surface of the object S. The reason is presumed to be that, since the surface of the object S has the surface with the glossy state, more regular reflection light components are incident on the image sensor 14 from the surface of the object S than the surface with the matte state.

[0143] Such a series of processes of checking the surface state of the object S by the processing device 20 is executed in accordance with, for example, the flowchart shown in FIG. 9 using the program 24a stored in the storage section 24. Figure 8 Further, a threshold value (allowable range) related to the shift in the direction of the first reference vector, a threshold value (allowable range) related to the shift in the direction of the second reference vector are set, for example, stored in the storage section 24. Here, it is assumed that the surface state of the object S is the surface with the matte state.

[0144] The processor 22 acquires the relationship between the color filter 34 and the wavelength accepted by the image sensor 14 when checking the surface state of the object S, and acquires the image using the image sensor 14 of the camera 13 (step ST1). At this time, the processor 22 causes the image acquired by the image sensor 14 of the camera 13 (for example, refer to the left side of FIG. 8) to be displayed on the display 6. Figure 10

[0145] The processor 22 calculates the color vector for each of the pixels in the entire range or the predetermined range of the light receiving section 14a of the image sensor 14 based on the output grayscale (pixel value) IR, IB of the color channels (here, two of the R channel and the B channel) of the respective pixels (step ST2). As shown in FIG. 10, the collection of the infinite number of points M is represented in a line shape. Figure 11

[0146] ​​The processor 22 calculates an average color vector C2M from the aggregate M of the innumerable points (step ST3). That is, the processor 22 calculates the angle or slope of the color vector C2M.

[0147] The processor 22 compares the calculated color vector C2M with the first reference vector and the second reference vector of the reference vector data 24b (step ST4). That is, the direction (angle or slope) of the color vector is collated with the direction (angle or slope) of the reference vector that is the same as or closest to the color vector C2M from among the plurality of reference vector data.

[0148] Here, the surface state of the object S is a surface in a matte state. The color vector C2M coincides with or approximately coincides with the direction of the first reference vector and deviates from the direction of the second reference vector.

[0149] The processor 22 outputs the surface state of the object S as an inspection determination result depending on whether or not it is within the threshold of the first reference vector (step ST5). At this time, the processor 22 causes the display 6 to display the determination result, for example. For example, on the display 6, the difference (including the threshold) in the angle from the first reference vector is displayed in the case where the surface of the object S is in a matte state.

[0150] The surface state of the object S to be inspected next is assumed to be a surface in a glossy state.

[0151] The processor 22 acquires the relationship between the color filter 34 and the wavelength received by the image sensor 14 when inspecting the surface state of the object S and acquires an image using the image sensor 14 of the camera 13 (step ST1). At this time, the processor 22 causes the image acquired by the image sensor 14 of the camera 13 (for example, refer to the right side of FIG. 10) to be displayed on the display 6. Figure 10

[0152] The processor 22 calculates a color vector for each of the pixels in the entire range or a predetermined range of the light-receiving portion 14a of the image sensor 14, based on the output grayscale (pixel value) IR, IB of the color channels (two of the R channel and the B channel here) of the pixels (step ST2). As shown in FIG. 11, the aggregate G of the innumerable points is represented as a block. Figure 11

[0153] The processor 22 calculates an average color vector C2G from the aggregate G of the innumerable points (step ST3). That is, the processor 22 calculates the angle or slope of the color vector C2G.

[0154] ​​Processor 22 compares the calculated color vector C2G with the first and second reference vectors of the reference vector data 24b (step ST4). That is, the direction (angle or slope) of the color vector is compared from the multiple reference vector data with the direction (angle or slope) of the reference vector that is the same as or closest to the color vector C2G.

[0155] Here, the surface of the object S being inspected is a glossy surface. The color vector C2G is aligned with or approximately aligned with the direction of the second reference vector, but deviates from the direction of the first reference vector.

[0156] Processor 22 outputs the surface state of the inspected object S as an inspection judgment result based on whether it is within the threshold of the second reference vector (step ST5). At this time, processor 22, for example, causes display 6 to display the judgment result. For example, on display 6, with the surface of the inspected object S in a bright state, the difference in angle with the second reference vector (including the threshold) is displayed.

[0157] Although not illustrated, the direction of the color vector of the image of the surface of the inspected object S is assumed to deviate from the first reference vector and the second reference vector, respectively, after considering thresholds. In this case, the processing device 20 displays, for example, a determination result on the display 6 that the surface of the inspected object S is not the desired surface state.

[0158] Furthermore, the inspection determination signal of the test object S in the processing device 20 can be used as an action trigger signal for a device that separates paper with a matte (dull) surface, paper with a glossy (glossy) surface, and other (paper with a surface that is not the desired surface state) into, for example, three lines as the test object S.

[0159] In this embodiment, it is explained that according to Figure 9 The examples shown are paper with matte (dull) surfaces and paper with glossy (glossy) surfaces, calculated from images of their surfaces, and used as reference vectors. Alternatively, color vectors calculated from images of numerous paper surfaces can be stored as reference vectors in storage unit 24. In this case, processing device 20 can output (determine) the surface roughness of the surface of the inspected object S by comparing the color vectors calculated from images of the inspected object S captured by camera 13 with, for example, reference vector data 24b stored in storage unit 24.

[0160] Therefore, the processing apparatus 20 according to this embodiment, by appropriately setting multiple reference vectors and comparing them with color vectors calculated based on the image of the object under inspection S, can perform the detection of the presence or absence of the detected part S2 as described in the first embodiment (see reference). Figure 6 In addition to determining parameters such as surface roughness, it can also check other parameters such as surface roughness.

[0161] According to the present embodiment, an optical inspection method, an optical inspection program 24a, a processing device 20, and an optical inspection device 4 that can well inspect the surface state of an object S can be provided.

[0162] Further, the surface of the object S has various states, for example, a matte state and a glossy state, respectively. By comparing the direction of the color vector Cn involved in the present embodiment with the closest reference vector in the reference vector data, the surface state can be determined with or without stages.

[0163] (Modified Example)

[0164] For example, the color vector obtained from the image of the standard surface S1 shown in FIG. 1 is taken as the first reference vector. Further, although not shown, the color vector of IR along the horizontal axis of the color coordinate system is assumed and taken as the second reference vector. These first and second reference vectors are stored in the storage section 24, for example. As one example, the first reference vector is a color vector corresponding to the direction of regular reflection from the surface of the object S, and the second reference vector is a color vector corresponding to a scattering direction different from the direction of regular reflection. Figure 4

[0165] Then, when the color vector is calculated from the image of the surface of a certain object S, the processing device 20 can also discriminate the state of the surface and the kind of the surface depending on whether the direction of the color vector is closer to the direction of the first reference vector or the direction of the second reference vector.

[0166] In this way, the reference vectors can be appropriately set depending on the object S.

[0167] Further, in the case of using the color filter explained in the modified example of the first embodiment, as one example, the first reference vector is a color vector corresponding to the first scattering direction from the surface of the object S, and the second reference vector is a color vector corresponding to the second scattering direction different from the first scattering direction.

[0168] (Third Embodiment)

[0169] The third embodiment will be explained using Figures 12 to 14 The third embodiment is a modified example of the first and second embodiments, and the same symbols are attached to the same parts or parts having the same function as those explained in the first and second embodiments, and detailed explanation will be omitted.

[0170] As shown in FIG. 6, the color vector Cn is calculated from the image of the surface of the object S. Figure 12 ​As shown, the optical device 12 has an imaging optical system 32 and a color filter 134. The color filter 134 is disposed at a focal plane of the imaging optical system 32 at a distance f. However, the color filter 134 can be disposed either on the front side or on the rear side of the imaging optical system 32. By disposing the color filter 134 at the focal plane of the imaging optical system 32, it is possible to make the color and direction relationship constant over the entire surface of the captured image.

[0171] Here, an example in which the color filter 34 of the optical device 12 of the optical inspection device 4 according to the first embodiment and the second embodiment is rotationally symmetrical, i.e., isotropic, with respect to the optical axis C is described. Here, rotationally symmetrical means that the shape coincides with a shape having a rotation angle of less than 360 degrees when the shape is rotated with respect to an axis. In the present embodiment, an example in which the color filter 134 is not isotropic is described.

[0172] The color filter 134 is formed in a rectangular shape, for example, with one direction orthogonal to the optical axis C (a direction parallel to the second axis Ay described later) as the length direction. In the present embodiment, the color filter 134 selectively transmits the first wavelength and a second wavelength different from the first wavelength. The color filter 134 has a first wavelength selection filter (wavelength selection region) 142 and a second wavelength selection filter (wavelength selection region) 144. Further, the color filter 134 has a light blocking portion 146 around the first wavelength selection filter 142 and the second wavelength selection filter 144. The light blocking portion 146 is formed by a black plate, for example, and holds the first wavelength selection filter 142 and the second wavelength selection filter 144.

[0173] Here, in the present embodiment, the first axis Ax is disposed orthogonal to the optical axis C of the imaging optical system 32. In the present embodiment, the regions of the first wavelength selection filter 142 and the second wavelength selection filter 144 are separated in the axial direction of the first axis Ax. That is, when the first wavelength selection filter 142 is moved in parallel in the axial direction of the first axis Ax, the end portion of the first wavelength selection filter 142 can be overlapped with the end portion of the second wavelength selection filter 144. This is referred to as the first wavelength selection filter 142 and the second wavelength selection filter 144 being disposed offset in the first axis Ax. In the present embodiment, the second axis Ay is disposed in a direction orthogonal to both the first axis Ax and the optical axis C. In the present embodiment, the axial direction of the second axis Ay is along the length direction of the color filter 134.

[0174] The first wavelength selection filter 142 and the second wavelength selection filter 144 are formed along the length direction of the color filter 134. The first wavelength selection filter 142 is disposed on the optical axis C. The first wavelength selection filter 142 is adjacent to the second wavelength selection filter 144. The first wavelength selection filter 142 and the second wavelength selection filter 144 of the color filter 134 are formed symmetrically with respect to an axis parallel to the second axis Ay.

[0175] The first wavelength selection filter 142 transmits light having a first wavelength (first light). For example, the first wavelength is set to blue light (435 nm) and B light having a first wavelength (400 nm to 500 nm) around the first wavelength. The second wavelength selection filter 144 transmits light having a second wavelength (second light). The second wavelength is set to red light (700 nm) and R light having a second wavelength (600 nm to 700 nm) around the second wavelength. The first wavelength selection filter 142 blocks light having a wavelength different from the first wavelength (including the second wavelength). The second wavelength selection filter 144 blocks light having a wavelength different from the second wavelength (including the first wavelength).

[0176] The image sensor 14 can be an area sensor or a line sensor. In addition, the image sensor 14 can have color channels of three channels of R, G, and B in each pixel. Here, as shown in FIG. 1, the image sensor 14 is set to an area sensor and is set to have two color channels of red and blue in each pixel. That is, the image sensor 14 can receive B light and R light respectively using independent color channels. Figure 12

[0177] A plane in which the first axis Ax and the optical axis C are spread is set to a first plane (imaginary plane), and a plane in which the second axis Ay and the optical axis C are spread is set to a second plane (imaginary plane). In Figure 13 , a cross-sectional view of the optical inspection device 4 along the first plane is shown. In Figure 14 , a cross-sectional view of the optical inspection device 4 along the second plane is shown.

[0178] As shown in Figure 12 and Figure 13 , light in which light from the object S is parallel to the optical axis C and is located in the first plane is set to a first light group L1. The first light group L1 is represented by considering two lights of a first light L1a and a first light L1b. Light in which light from the object side is inclined with respect to the optical axis C and is located in the first plane is set to a second light group L2. The second light group L2 is represented by considering two lights of a second light L2a and a second light L2b.

[0179] As shown in Figure 12 and Figure 14 ​As shown, light rays from the object side that are parallel to the optical axis C and that lie in the 2nd surface are set as a 3rd light ray group. A 3rd light ray L3 is considered as representative of the 3rd light ray group. Light rays from the object side that are inclined with respect to the optical axis C and that lie in the 2nd surface are set as a 4th light ray group. A 4th light ray L4 is considered as representative of the 4th light ray group.

[0180] As shown, a surface parallel to the 1st surface intersects the 1st wavelength selective filter 142 and the 2nd wavelength selective filter 144 of the color filter 134 at the same time. That is, a surface parallel to the 1st surface intersects at least two different wavelength selective filters 142, 144 of the color filter 134. As shown, a surface parallel to the 2nd surface intersects one wavelength selective filter 142 of the color filter 134. That is, in the color filter 134, the number of intersections of the wavelength selective filters 142, 144 of the color filter 134 in the 1st surface and the 2nd surface is different, so it is anisotropic, and anisotropy exists. In other words, in the color filter 134, the distribution of the wavelength selective filters 142, 144 is different depending on the directions of the 1st axis Ax and the 2nd axis Ay, and becomes anisotropic. Figure 12 Figure 13 As shown, a surface parallel to the 1st surface intersects the 1st wavelength selective filter 142 and the 2nd wavelength selective filter 144 of the color filter 134 at the same time. That is, a surface parallel to the 1st surface intersects at least two different wavelength selective filters 142, 144 of the color filter 134. As shown, a surface parallel to the 2nd surface intersects one wavelength selective filter 142 of the color filter 134. That is, in the color filter 134, the number of intersections of the wavelength selective filters 142, 144 of the color filter 134 in the 1st surface and the 2nd surface is different, so it is anisotropic, and anisotropy exists. In other words, in the color filter 134, the distribution of the wavelength selective filters 142, 144 is different depending on the directions of the 1st axis Ax and the 2nd axis Ay, and becomes anisotropic. Figure 12 Figure 14 As shown, a surface parallel to the 1st surface intersects the 1st wavelength selective filter 142 and the 2nd wavelength selective filter 144 of the color filter 134 at the same time. That is, a surface parallel to the 1st surface intersects at least two different wavelength selective filters 142, 144 of the color filter 134. As shown, a surface parallel to the 2nd surface intersects one wavelength selective filter 142 of the color filter 134. That is, in the color filter 134, the number of intersections of the wavelength selective filters 142, 144 of the color filter 134 in the 1st surface and the 2nd surface is different, so it is anisotropic, and anisotropy exists. In other words, in the color filter 134, the distribution of the wavelength selective filters 142, 144 is different depending on the directions of the 1st axis Ax and the 2nd axis Ay, and becomes anisotropic.

[0181] In an optical system in which light rays from an object point O of an object S are imaged as image points by the imaging optical system 32, in general, an optical system in which a chief ray on the object side is parallel to the optical axis C is called an object side telecentric optical system. In the present embodiment, when a light ray on the object side that is substantially parallel to the optical axis C is imaged by the imaging optical system 32, the light ray has object side telecentricity. On the other hand, when a light ray on the object side that is substantially not parallel to the optical axis C but is inclined is imaged by the imaging optical system 32, the light ray has object side non-telecentricity.

[0182] The light rays L1a, L1b of the 1st light ray group from the object side are parallel to the optical axis C. The light rays L1a, L1b reach the focal point of the focal plane of the imaging optical system 32. Therefore, the 1st light rays L1a, L1b reach the 1st wavelength selective filter 142 of the color filter 134 provided on the focal plane. That is, the 1st light rays L1a, L1b having telecentricity in the 1st surface reach the 1st wavelength selective filter 142.

[0183] The light rays L2a, L2b of the 2nd light ray group from the object side are inclined with respect to the optical axis C in the 1st surface. The light rays L2a, L2b of the 2nd light ray group are out of focus in the focal plane of the imaging optical system 32, and reach, for example, the 2nd wavelength selective filter 144. That is, the 2nd light rays L2a, L2b reach the 2nd wavelength selective filter 144. That is, the light rays L2a, L2b having non-telecentricity in the 1st surface reach the 2nd wavelength selective filter 144. ​​

[0184] Further, the part of the object side light rays inclined with respect to the optical axis C in the first plane reaches the light ray blocking portion 146 in addition to the second wavelength selective filter 144.

[0185] The light rays L3 of the third light ray group from the object side are parallel to the optical axis C in the second plane. The light rays L3 of the third light ray group reach the focal point of the focal plane of the imaging optical system 32. Therefore, the third light rays L3 reach the first wavelength selective filter 142 of the color filter 134 provided at the focal plane. That is, the light rays L3 having telecentricity in the second plane reach the first wavelength selective filter 142.

[0186] The light rays L4 of the fourth light ray group from the object side are inclined with respect to the optical axis C in the second plane. The light rays L4 of the fourth light ray group reach the first wavelength selective filter 142 at a position deviated from the focal point in the focal plane of the imaging optical system 32. That is, the fourth light rays L4 reach the first wavelength selective filter 142. That is, the light rays having non-telecentricity in the second plane reach the first wavelength selective filter 142.

[0187] Further, the object side light rays inclined with respect to the optical axis C in the second plane do not reach the light ray blocking portion 146.

[0188] Thus, the light rays Lla, Llb having telecentricity in the first plane and the light rays L2a, L2b having non-telecentricity reach different wavelength selective regions, respectively. On the other hand, the light rays L3 having telecentricity and the light rays L4 having non-telecentricity in the second plane both reach the same wavelength selective filter 142.

[0189] The case where the path of an arbitrary light ray reaching the imaging optical system 32 from the object side in an arbitrary direction is projected onto the first plane (refer to Figure 12 and Figure 13 ) and the case where the path is projected onto the second plane (refer to Figure 12 and Figure 14 ) are considered. For these projected light rays, the above properties are also respectively satisfied. That is, the light rays having telecentricity and the light rays having non-telecentricity projected onto the first plane reach different wavelength selective regions of the color filter 134. On the other hand, the light rays having telecentricity and the light rays having non-telecentricity projected onto the second plane both reach the same wavelength selective filter 142.

[0190] In a case where the image sensor 14 of the optical inspection apparatus 4 according to the present embodiment captures B light (light of the first wavelength) from the object, that is, in a case where B image data Ib is obtained, the first wavelength selection filter 142 of the color filter 134 emits the B light toward the image sensor 14. At this time, the first wavelength selection filter 142 of the color filter 134 blocks R light (light of the second wavelength). The B light has telecentricity in the axial direction of the first axis Ax. Therefore, the optical inspection apparatus 4 can obtain the B image data Ib having telecentricity by the image sensor 14.

[0191] In a case where the image sensor 14 of the optical inspection apparatus 4 according to the present embodiment captures R light (light of the second wavelength) from the object, that is, in a case where R image data Ir is obtained, the second wavelength selection filter 144 of the color filter 134 emits the R light toward the image sensor 14. At this time, the second wavelength selection filter 144 of the color filter 134 blocks B light (light of the first wavelength). The R light has non-telecentricity in both the axial direction of the first axis Ax and the axial direction of the second axis Ay. This can also be said to have eccentricity. That is, the optical inspection apparatus 4 can obtain an eccentric image of the R light by the image sensor 14. Thus, the optical inspection apparatus 4 can obtain an image having a large angle of view.

[0192] Thus, the image sensor 14 of the optical inspection apparatus 4 according to the present embodiment simultaneously obtains images of B light (for example, corresponding to regular reflection light) and R light (for example, corresponding to scattered light) in the direction of the first axis Ax.

[0193] Thus, the color filter 134 provided at the focal plane of the imaging optical system 32 between the imaging optical system 32 and the image sensor 14 emits light of the first wavelength (for example, B light) and light of the second wavelength (for example, R light) different from the first wavelength toward the image sensor 14 according to the direction of the light from the object S. Then, the color filter 134 obtains information of a first image related to the first wavelength and information of a second image related to light of the second wavelength in the image sensor 14. At this time, the image sensor 14 simultaneously obtains images of the first wavelength and the second wavelength after the color filter 134.

[0194] Further, the light intensities of the R image data Ir and the B image data Ib acquired in each pixel of the image sensor 14 of the optical inspection device 4 according to the present embodiment complementarily change when the light amount of the reflected light from the object point on the object S is considered to be constant. That is, when the light intensity of the R light in the reflected light from the object S through the color filter 134 in a certain pixel becomes strong, the light intensity of the B light in the pixel becomes weak. In addition, when the light intensity of the B light in another certain pixel becomes strong, the light intensity of the R light in the pixel becomes weak. This is because the color and the direction of the light are corresponding. That is, when the reflected light component concentrates in a certain direction while the intensity of the reflected light (for example, R light) is constant, the remaining directional component equivalent to the B light, the G light becomes small.

[0195] For example, assume that the surface of the object S is a standard surface S1 as shown in Figure 4 This time, the light from the standard surface S1 among the light incident to the image sensor 14 through the color filter 134 of the camera 13 is based on the B light on the optical axis C (on the area Al) through the color filter 134. Therefore, the image sensor 14 obtains the image of the regular reflection light from the standard surface S1 as blue in the B image data Ib. Figure 4 The B image data Ib of the standard surface S1 of the object S as shown in

[0196] For the image sensor 14, the R light among the light from the position equivalent to the standard surface S1 does not incident, or even if it incident, the pixel value is small to the extent that it can be ignored. Therefore, the image of the standard surface S1 in the R image data Ir becomes black.

[0197] In addition, in the present embodiment, the G light among the light incident to the image sensor 14 through the color filter 134 from the surface of the object S does not incident, or even if it incident, the pixel value is small to the extent that it can be ignored. Therefore, the G image data Ig becomes black as a whole.

[0198] Therefore, the RGB image data Irgb obtained by the optical inspection device 4 according to the present embodiment is attached with the color corresponding to the directional information of the light based on the color filter 34. The R image data Ir, the G image data Ig, and the B image data Ib obtained by separating the RGB image data Irgb into each color channel respectively become the images based on the surface information (the unevenness information) of the object S. In this way, the optical inspection device 4 according to the present embodiment acquires the structure (unevenness) information of the object S by the image captured by the image sensor 14.

[0199] Further, in the case where the surface of the object S is a standard surface S1 as shown in Figure 4 a color coordinate system as shown in Figure 5 is obtained.

[0200] For example, assume that the surface of the object S has a detected portion S2 in the standard surface S1 illustrated in Figure 6

[0201] The light from the standard surface S1 among the light incident to the image sensor 14 through the color filter 134 of the camera 13 is based on the B light on the optical axis C (on the region Al) through the color filter 34. Therefore, the image sensor 14 obtains the regular reflection light from the standard surface S1 as a blue image in the B image data Ib.

[0202] In the present embodiment, the light from the position corresponding to the detected portion S2 is not incident to the image sensor 14 as the B light in the first surface (refer to Figure 13 ). On the other hand, the light from the position corresponding to the detected portion S2 is incident to the image sensor 14 as the B light in the second surface (refer to Figure 14 ).

[0203] In addition, the light from the position corresponding to the detected portion S2 is incident to the image sensor 14 as the R light in the first surface (refer to Figure 13 ). In addition, although not illustrated, with respect to the light from the position corresponding to the detected portion S2, in the second wavelength selection filter 144 parallel to the second surface (refer to Figure 14 ), the R light is transmitted and is incident to the image sensor 14 as the R light.

[0204] Therefore, in a case where the surface of the object S has the detected portion S2 in the standard surface S1 illustrated in Figure 6 , a graph of a color coordinate system as illustrated in Figure 7 is obtained.

[0205] Therefore, according to the surface state of the object S, Figure 5 the direction of the color vector as illustrated in Figure 7 changes. Therefore, by using the camera 13 (refer to Figures 12 to 14 ) of the optical inspection device 4 related to the present embodiment, with the processing device 20 as illustrated in Figure 1 , the processing explained in the first embodiment can be performed, and the surface state of the surface of the object S can be inspected.

[0206] In addition, assume that the surface of the object S is in the state as illustrated in Figure 9 and Figure 10 of the second embodiment. In this case, by using the camera 13 (refer to Figures 12 to 14 ) of the optical inspection device 4 related to the present embodiment, the reference vector data 24b is set as explained in the second embodiment, and the surface state of the surface of the object S can also be discriminated. ​

[0207] According to the present embodiment, an optical inspection method, an optical inspection program 24a, a processing device 20, and an optical inspection device 4 capable of well inspecting the surface state of an object S can be provided.

[0208] (4th Embodiment)

[0209] Using Figure 15 and Figure 16 The 4th embodiment will be described. The present embodiment is a modification of the 1st to 3rd embodiments, and the same reference signs are attached to the same components as those described in the 1st to 3rd embodiments or components having the same functions, and detailed description will be omitted.

[0210] As Figure 15 shown, the optical device 12 is provided with a color filter (wavelength selection section) 234 and an imaging optical system (imaging lens) 32. In the present embodiment, the imaging optical system 32 is disposed between the color filter 234 and the image sensor 14. The image sensor 14 has a light-receiving section (light-receiving surface) 14a that becomes an imaging surface at a distance L from the imaging optical system 32. The optical device 12 and the image sensor 14 constitute a so-called camera (imaging section) 13.

[0211] The color filter 234 has a 1st wavelength selection region 242, a 2nd wavelength selection region 244, and a 3rd wavelength selection region 246 in a certain cross section. The 1st wavelength selection region 242 and the 2nd wavelength selection region 244 transmit light in different wavelength ranges. The 3rd wavelength selection region 246 can transmit light of the same wavelength as the 2nd wavelength selection region 244, for example.

[0212] Further, instead of the color filter 234, the color filter 34 described in the 1st embodiment can be used, and the color filter 134 described in the 3rd embodiment can also be used.

[0213] The light source 16 according to the present embodiment can irradiate the object S with directional illumination light. The illumination light from the light source 16 is irradiated in a state inclined with respect to the surface of the object S.

[0214] The operation of the optical inspection system 2 according to the present embodiment will be described.

[0215] In Figure 15 the present embodiment, the surface of the object S is assumed to be a mirror surface (standard surface) S1. On this surface, there is an inspection target portion S2 that is a minute defect having a diffusing surface. At this time, a 1st object point O1 is taken on the mirror surface of the object S, and a 2nd object point O2 is taken on the inspection target portion S2.

[0216] The illumination light incident to the first object point Ol is reflected at the first object point Ol as the first reflected light LI. The incident angle of the illumination light incident to the first object point Ol and the reflection angle of the light reflected at the first object point Ol coincide with respect to the optical axis of the imaging optical system 32.

[0217] The first object point Ol is located on the surface of the mirror, so the number of the specular reflection components (regular reflection components) in the light increases. Here, the illumination light from the light source 16 has directivity, so the direction of the specular reflection components is determined in accordance with the direction. That is, the light distribution of the first reflected light easily becomes a narrow angular distribution as shown by the symbol LI in FIG. 6. Figure 15

[0218] The light incident to the second object point O2 is reflected as the second reflected light L21, L22. The second object point O2 is located on, for example, a rough surface, so the second reflected light contains a diffusion component L22. However, the illumination light from the light source 16 has directivity. Therefore, the second reflected light also contains a specular reflection component L21. That is, the light distribution of the light has the diffusion component L22 as well as the specular reflection component L21 as shown by the symbols L21, L22 in FIG. 7. That is, the light distribution of the second reflected light easily becomes a wide angular distribution. Figure 15

[0219] In the second object point O2 having a slight defect, the second reflected light has the diffusion component L22 and the specular reflection component L21. The light passes through the color filter 234 and further passes through the imaging optical system 32. At this time, in the color filter 234, the light selectively passes through the first wavelength selection region 242 and the second wavelength selection region 244. The light passing through the first wavelength selection region 242 becomes blue (B) light in the wavelength range of, for example, 400 nm to 500 nm. The light passing through the second wavelength selection region 244 becomes red (R) light in the wavelength range of, for example, 600 nm to 700 nm. That is, the second reflected light passes through at least two or more different wavelength selection regions 242, 244. Then, the imaging is performed on the image sensor 14 by the imaging optical system 32. The second reflected light from the second object point O2 is imaged on the image sensor 14 by the third wavelength selection region 246 in accordance with the reflection direction.

[0220] In the first object point Ol having no slight defect, the first reflected light becomes a substantially specular reflection component LI. Therefore, the first reflected light passes through the second wavelength selection region 244 of the color filter 234. The light of the specular reflection component LI passing through the second wavelength selection region 244 becomes red (R) light in the wavelength range of, for example, 600 nm to 700 nm.

[0221] ​​The color vector C2 = (IR, IB) corresponding to each object point Ol, O2 is calculated by the processing device 20. The color vector C21 corresponding to the first object point Ol has a red intensity component (IR). The color vector C22 corresponding to the second object point O2 has a blue intensity component (IB) and a red intensity component (IR).

[0222] Thus, the direction of the color vector C21 at the first object point Ol without a minute defect and the direction of the color vector C22 at the second object point O2 as a minute defect are different. That is, it is possible to identify the presence / absence of a minute defect depending on the directions of the color vectors C21, C22.

[0223] As described above, by taking the color vector C21 based on the first reflected light from the first object point Ol as a reference vector, comparing the color vector C2 in each pixel based on the second reflected light from the second object point O2 with the reference vector, it is possible to determine the surface state of the object S. Moreover, the identification of the presence / absence of a minute defect is output in accordance with the flowchart shown in FIG. 9 based on the optical inspection program 24a, the reference vector data 24b explained in the first embodiment. Figure 8

[0224] In the present embodiment, an example in which the illumination light from the light source 16 is obliquely incident with respect to the object S is explained. In this way, the illumination light from the light source 16 is not limited to coaxial overhead illumination, and illumination light from various directions can be used. With such illumination light, it is also possible to compare the calculation results obtained by the processing device 20 calculating the color vector Cn with the reference vector, and determine the surface state of the object S.

[0225] Thus, according to the present embodiment, it is possible to provide an optical inspection method, an optical inspection program 24a, a processing device 20, and an optical inspection device 4 that can well inspect the surface state of an object S.

[0226] Further, the position of the color filter 234 can be either between the object S and the imaging optical system 32 or between the imaging optical system 32 and the image sensor 14. In the case where the imaging optical system 32 is constituted by a plurality of lenses, for example, the color filter 234 can be disposed between the plurality of lenses.

[0227] According to at least one embodiment described above, it is possible to provide an optical inspection method, an optical inspection program 24a, a processing device 20, and an optical inspection device 4 that can well inspect the surface state of an object S.

[0228] ​While several embodiments of the present application have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the application. The embodiments can be implemented in other various forms, and various omissions, substitutions, and changes can be made thereto without departing from the scope of the application. The embodiments, variations thereof, fall within the scope, spirit, and gist of the application, and fall within the scope of the application recited in the claims and the equivalents thereof.

Claims

1. An optical inspection method of a surface state of an object, comprising: acquiring, for each pixel of an image sensor, a color vector of a color corresponding to a plurality of mutually different wavelengths selectively passed through a wavelength selection section by optical imaging using the wavelength selection section, in an n-dimensional color coordinate system having the same number of color channels as a number of color channels of each pixel of the image sensor or less than the number, where n is a natural number of 1 or more; calculating an average color vector that is an average color vector according to a collection of pixel values of each pixel; and determining a surface state of the object based on a direction of the average color vector in the color coordinate system.

2. The optical inspection method according to claim 1, wherein the optical inspection method includes associating the direction of the color vector in the color coordinate system with the color.

3. The optical inspection method according to claim 1 or 2, wherein the directions of light from the object are different for the plurality of mutually different wavelengths, respectively.

4. The optical inspection method according to claim 1 or 2, wherein determining a surface state of the object includes setting a reference vector that is a reference for determination of the surface state of the object, and determining based on a difference between the reference vector and the direction of the color vector.

5. The optical inspection method according to claim 1 or 2, wherein determining a surface state of the object includes calculating a closeness between a reference vector that is a reference for determination of the surface state of the object and the direction of the color vector.

6. The optical inspection method according to claim 1 or 2, wherein when a color vector corresponding to a direction of normal reflection or a first scattering direction from a surface of the object is set as a first reference vector, and a color vector corresponding to a second scattering direction different from the direction of normal reflection or the first scattering direction is set as a second reference vector, determining a surface state of the object includes determining a kind of the surface based on whether the direction of the color vector is closer to the direction of the first reference vector or the direction of the second reference vector.

7. An optical inspection program product of a surface state of an object, causing a computer to perform: acquiring, for each pixel of an image sensor, a color vector of a color corresponding to a plurality of mutually different wavelengths selectively passed through a wavelength selection section by optical imaging using the wavelength selection section, in an n-dimensional color coordinate system having the same number of color channels as a number of color channels of each pixel of the image sensor or less than the number, where n is a natural number of 1 or more; calculating an average color vector that is an average color vector according to a collection of pixel values of each pixel; and determining a surface state of the object based on a direction of the average color vector in the color coordinate system.

8. A processing device used in optical inspection of a surface state of an object, comprising a processor that By using optical imaging with a wavelength selection section that selectively passes a plurality of wavelengths that are mutually different from the surface of an object, a color vector of a color corresponding to the wavelengths is acquired for each pixel in an n-dimensional color coordinate system that is the same number of color channels as each pixel of an image sensor or less than that number, where n is a natural number of 1 or more, an average color vector is calculated that is an average color vector from a collection of pixel values of each pixel, a surface state of the object is discriminated from a direction of the average color vector in the color coordinate system.

9. An optical inspection apparatus having: a photographing section having: A wavelength selection section is provided at a position of a focal point of the imaging optical system to selectively pass a plurality of wavelengths different from each other from the surface of the object; and an image sensor that photographs light that has passed through the wavelength selection section; and the processing apparatus of claim 8 acquires the color vector from an image acquired by the image sensor and discriminates a surface state of the object from a direction of the color vector.

Images