JP2022001844A - Illumination device and inspection device - Google Patents

Abstract

To facilitate detection of defects such as cracks in inspection of a surface to be inspected in which a reflective surface and a diffusive surface coexist.SOLUTION: An inspection device 100 includes a camera 110 for imaging a surface to be inspected 102, and an illumination device (illumination part) 200 for irradiating the surface to be inspected 102. The illumination device 200 has a reflecting light illumination part (bright-field illumination part) 210 for emitting light reflected by the surface to be inspected 102 and made incident on the camera 110, and a diffusing light illumination part (dark-field illumination part) 220 for emitting light diffused by the surface to be inspected 102 and made incident on the camera 110. Also, in the field of view range 105 of the camera 110, there is a virtual image 211 of the light source of the reflecting light illumination part 210 having the surface to be inspected 102 as a virtual mirror surface, and there is no virtual image 221 of the light source of the diffusing light illumination part 220 having the surface to be inspected 102 as a virtual mirror surface.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lighting device and an inspection device, and relates to a technique effective for inspecting an inner wall of a container such as a nuclear reactor.

Japanese Unexamined Patent Publication No. 2003-185783 (Patent Document 1) describes an inspection device that captures an image of the inside of a reactor pressure vessel with a camera and visually inspects the inside with an image. Japanese Unexamined Patent Publication No. 2011-317788 (Patent Document 2) describes a method of visually recognizing defects such as cracks in concrete from the difference between images taken by selectively turning on a plurality of lights. In Japanese Patent Application Laid-Open No. 2019-517003 (Patent Document 3), although it is not an inspection device for the inner wall of the container, the difference between the line image captured under dark-field illumination and the line image captured under bright-field illumination. Therefore, a method for identifying a region having high reflectance on the surface of a sheet element such as paper is described.
The configuration is described.

Japanese Unexamined Patent Publication No. 2003-185783 Japanese Unexamined Patent Publication No. 2011-317788 Special Table 2019-517003 Gazette

As a method of inspecting defects such as cracks generated in the inner wall of a container such as a nuclear reactor, there is a method of arranging a camera in the container and illuminating the inner wall of the test surface to take an image. When the container is made of a metal such as stainless steel, the inner wall surface is generally a reflective surface, but with some regions having a partially diffusive texture. Thus, when inspecting cracks on an inner wall surface where reflective and diffusive surfaces coexist, it is difficult to distinguish between cracks and diffusive textures in the resulting image.

An object of the present invention is to provide a technique for facilitating the detection of defects such as cracks in an inspection of a surface to be inspected in which a reflective surface and a diffusive surface are mixed.

The lighting device according to the embodiment has a reflected light illuminating unit that irradiates light reflected on the surface to be inspected and incident on the camera, and diffusion that diffuses on the surface to be inspected and irradiates light incident on the camera. It has an illumination unit for light. In the field of view of the camera, there is a virtual image of the light source of the reflected light illumination unit having the subject surface as a virtual mirror surface, and the diffused light illumination unit having the subject surface as a virtual mirror surface. There is no virtual image of the light source.

The inspection device according to another embodiment includes a camera that images the surface to be inspected, a lighting unit for reflected light that is reflected by the surface to be inspected and irradiates light incident on the camera, and diffused on the surface to be inspected. It has a diffused light illuminating unit that irradiates the light incident on the camera. In the field of view of the camera, there is a virtual image of the light source of the reflected light illumination unit having the subject surface as a virtual mirror surface, and the diffused light illumination unit having the subject surface as a virtual mirror surface. There is no virtual image of the light source.

According to the invention disclosed in the present application, it is possible to easily detect defects such as cracks in the inspection of the surface to be inspected in which the reflective surface and the diffusive surface are mixed.

Issues, configurations and effects other than those described above will be clarified by the description of the following embodiments.

It is explanatory drawing which shows typically the configuration example of the inspection apparatus which is one Embodiment. FIG. 3 is a plan view of the lighting device shown in FIG. 1 as viewed from the direction of the optical axis of the camera. It is explanatory drawing which shows typically the connection relation of the luminance control part provided in the lighting apparatus shown in FIG. It is explanatory drawing which shows typically the path of the light emitted from the illumination part for reflected light shown in FIG. 1. It is explanatory drawing which shows typically the path of the light emitted from the illumination part for diffused light shown in FIG. FIG. 3 is a plan view showing a part of the surface to be inspected shown in FIG. FIG. 6 is an enlarged cross-sectional view taken along the line AA shown in FIG. It is a figure which shows the difference of the appearance of an image by the balance of the luminance of the bright-field illumination (illumination for reflected light) and the illumination for dark-field illumination (illumination for diffused light) on the surface to be shown in FIG. It is explanatory drawing which shows the processing flow of the system which adjusts the brightness of bright-field illumination and dark-field illumination automatically. It is explanatory drawing which shows the configuration example of the computer which carries out each step of the balance adjustment shown in FIG. It is sectional drawing of the main part schematically showing the structural example of the inspection apparatus which is the modification with respect to FIG. It is sectional drawing of the main part schematically showing the structural example of the inspection apparatus which is another modification with respect to FIG. It is explanatory drawing which shows typically the path of the light emitted from the illumination part for reflected light shown in FIG. It is explanatory drawing which shows typically the path of the light emitted from the illumination part for diffused light shown in FIG.

In each of the drawings for explaining the following embodiments, the same members are designated by the same reference numerals in principle, and the repeated description thereof will be omitted. In addition, functionally the same elements may be displayed with the same number or the corresponding number. Further, in the following, hatching may be added even if it is a plan view in order to make the drawing easy to understand. The accompanying drawings show embodiments and implementation examples in accordance with the principles of the present disclosure, but these are for the purpose of understanding the present disclosure and are never used for the limited interpretation of the present disclosure. is not it. The description herein is exemplary.

In this embodiment, the description is given in sufficient detail for those skilled in the art to implement the present disclosure, but other implementations and embodiments are also possible and do not deviate from the scope and spirit of the technical idea of the present disclosure. It is necessary to understand that it is possible to change the structure and structure and replace various elements.

In the following description of the embodiment, as an example of the inspection device (and the lighting device which is a part of the inspection device), the inspection device for detecting the crack (defect) generated in the inner wall of the pressure vessel of the nuclear reactor will be taken up and described. .. However, the technique described below can be applied to various modifications.

<Configuration example of inspection device>
FIG. 1 is a cross-sectional view of a main part schematically showing a configuration example of the inspection device of the present embodiment. In FIG. 1, the visual field range 105 of the camera 110 through the lens 112, which is an imaging lens, is shown by a two-dot chain line, and the optical axis 113 of the camera 110 is shown by a two-dot chain line. FIG. 2 is a plan view of the lighting device shown in FIG. 1 as viewed from the direction of the optical axis of the camera. FIG. 3 is an explanatory diagram schematically showing the connection relationship of the luminance control unit included in the lighting device shown in FIG. FIG. 4 is an explanatory diagram schematically showing the path of light emitted from the illuminated light unit for reflected light shown in FIG. 1, and FIG. 5 is a schematic diagram of the path of light emitted from the illuminated unit for diffused light shown in FIG. It is explanatory drawing which shows. The inspection device 100 shown in FIG. 1 is a device that captures an image of the inner wall surface of the surface to be inspected (inspection target surface) 102 of the reactor (container) 101 with a camera 110 and detects a crack 104 that is a defect. Hereinafter, a method of inspecting the surface to be inspected 102 of the reactor 101 using the inspection device 100 will be described.

The inspection device 100 includes a camera 110 that captures an image of the surface to be inspected 102, and a lighting device (illumination unit) 200 that irradiates the surface to be inspected 102. The lighting device 200 includes a reflected light illuminating unit (bright-field illuminating unit) 210 that irradiates light reflected by the test surface 102 and incident on the camera 110, and light diffused on the test surface 102 and incident on the camera 110. It has a diffused light illumination unit (dark field illumination unit) 220 for irradiating the light. Further, within the viewing range 105 of the camera 110, there is a virtual image 211 of the light source of the light source for reflected light 210 having the subject surface 102 as a virtual mirror surface, and diffused light having the subject surface 102 as a virtual mirror surface. There is no virtual image 221 of the light source of the lighting unit 220. In other words, the virtual image 211 is within the field of view 105 of the camera 110, and the virtual image 221 is outside the field of view 105 of the field of view 105.

The camera 110 includes an image sensor 111 and a lens (imaging lens) 112 arranged between the image sensor 111 and the surface to be inspected 102. The surface to be inspected 102 exists on the extension line of the optical axis 113 connecting the image sensor 111 and the lens 112. The lens 112 has an angle of view range limited by conditions such as a range in which an image can be formed on the image sensor 111. This angle of view range corresponds to the field of view range 105 of the camera 110.

The camera 110 is electrically connected to the transmission circuit 120. The transmission circuit 120 is electrically connected to the display device 123 via the cable 121 and the image processing circuit 122. The image captured by the camera 110 is converted into a video signal of a digital video signal standard such as SDI, HDMI, and GigE by the transmission circuit 120, and transmitted to the image processing circuit 122. The video signal is processed by the image processing circuit 122 and transmitted to the display device 123. The display device 123 can display the image captured by the camera 110 in real time. Therefore, for example, when the operator is in front of the display device 123, the operator can observe the state of shooting by the camera 110 or the state of the surface to be inspected 102 based on the image displayed by the display device 123. ..

The camera 110 and the transmission circuit 120 are housed in a housing 106 made of a metal such as tungsten or lead that attenuates radiation. At the time of inspection of the surface to be inspected 102, the housing 106 is carried into the reactor 101. The cable 121 is provided so as to penetrate the housing 106 and is led out to the outside of the reactor 101. As described above, the parts (camera 110 and transmission circuit 120) carried into the reactor 101 are covered with the housing 106, so that the camera 110 and the transmission circuit 120 malfunction due to the influence of the radiation in the reactor 101. Can be suppressed.

As shown in FIG. 2, each of the reflected light illuminating unit 210 and the diffused light illuminating unit 220 is ring illumination formed in an annular shape, and is around the optical axis 113 of the camera 110 (see FIG. 1) and the lens 112. Is placed in. In the example shown in FIG. 2, an annular reflected light illuminating unit 210 is arranged around the optical axis, and a ring-shaped diffused light illuminating unit 220 is arranged on the outer periphery thereof. Each of the reflected light illumination unit 210 and the diffused light illumination unit 220 has a light source such as an LED (Light Emitting Diode) (not shown) and a diffusible light guide plate (not shown) that converts the light output from the light source into a surface light source. To prepare for.

As shown in FIG. 3, the lighting device 200 controls each of the brightness (light amount) of the light emitted from the reflected light lighting unit 210 and the brightness (light amount) of the light emitted from the diffused light lighting unit 220. It has a brightness control unit (light amount control unit) 230. The reflected light illumination unit 210 is electrically connected to the luminance control unit 230 via the cable 212. The diffused light illumination unit 220 is electrically connected to the luminance control unit 230 via the cable 222. The brightness control unit 230 can control the brightness of each of the reflected light illumination unit 210 and the diffused light illumination unit 220 independently of each other. For example, the brightness of either the reflected light illuminating unit 210 or the diffused light illuminating unit 220 can be set to zero (off state). The luminance control unit 230 is built in, for example, the camera 110 of FIG. Alternatively, it may be located outside the reactor 101 and the cables 212 and 222 may be pulled out to the outside of the reactor 101.

As described with reference to FIG. 1, within the viewing range 105 of the camera 110 included in the inspection device 100 of the present embodiment, the light source of the reflected light illumination unit 210 having the inspected surface 102 as a virtual mirror surface There is a virtual image 211, and there is no virtual image 221 of the light source of the diffused light illumination unit 220 having the test surface 102 as a virtual mirror surface. In this case, as schematically shown by the dotted line in FIG. 4, the light 213 emitted from the reflected light illumination unit 210 is reflected by the test surface 102 and received by the camera 110. Specifically, the light 213 reflected by the surface to be inspected 102 is received by the image sensor 111 via the lens 112. Further, as shown in FIG. 5, the light 223 emitted from the diffused light illumination unit 220 is reflected by the test surface 102 and is not received by the camera 110. Specifically, the light 223 reflected by the surface 102 to be inspected is reflected toward a position other than the lens 112, and as a result, the reflected light is not received. On the other hand, a part of the light diffused on the surface to be inspected 102 is incident on the lens 112 shown in FIGS. 4 and 5, and is received by the image sensor 111 via the lens 112.

In the case of the inspection method using the inspection device 100, each of the reflected light illumination unit 210 and the diffused light illumination unit 220 is used. By adjusting the relationship between the virtual image 211 and the virtual image 221 and the viewing range 105 of the camera 110, the light 213 (see FIG. 4) emitted from the reflected light illuminating unit 210 is mainly received by the camera 110. As for the light 223 emitted from the diffused light illumination unit 220, only the diffused light is received by the camera 110.

As described with reference to FIG. 2, the reflected light illumination unit 210 and the diffused light illumination unit 220 are ring illuminations, and the central portion has an opening for arranging the lens 112. Further, as shown in FIG. 1, the virtual image 211 of the light source of the reflected light illumination unit 210 does not exist on the optical axis 113 of the camera 110, and a hole is opened. Therefore, there is a concern that the region (central region) near the point overlapping with the optical axis 113 of the surface to be inspected 102 is more difficult to observe than the surrounding region. However, as described below, in the inspection of the surface to be inspected 102, the virtual image 211 is photographed in a blurred state. That is, in the inspection of the test surface 102, the lens 112 is arranged so as to focus on the test surface 102. Therefore, the virtual image 211 of the light source of the reflected light illumination unit 210 is out of focus, and the virtual image 211 is photographed in a blurred state. Therefore, the boundary between the hole and its periphery due to the opening in which the lens 112 is arranged is blurred and the light spreads. As a result, the holes are relaxed in the direction in which the light is filled. Further, since the blurred image is corrected by the image processing circuit 122, the corrected image can be confirmed when visually recognizing it on the display device 123.

<Control of two types of lighting>
Next, a method of controlling and inspecting the brightness of the reflected light illuminating unit 210 and the diffused light illuminating unit 220 will be described. FIG. 6 is a plan view showing a part of the surface to be inspected shown in FIG. FIG. 7 is an enlarged cross-sectional view taken along the line AA shown in FIG.

In the case of a metal container wall surface as in the present embodiment, it is considered that the surface of the wall surface is composed only of a surface that reflects most of the incident light and can be regarded as a mirror surface. However, as a result of investigation by the inventor of the present application, it was found that regions having different optical characteristics are distributed. That is, as shown in FIGS. 6 and 7, the test surface 102 has a region 131 having a diffusible characteristic in which more diffused light is scattered than regularly reflected light, and a region 131 having a diffusive characteristic and a specularly reflected light rather than a diffused light. The region 132, which has more reflective properties, is provided. The region 132 having the reflective property has an optical property that can be regarded as a mirror surface substantially. The diffusible regions 131 are dispersed between the reflective regions 132. It is necessary to detect the crack 104 in such a state that the optical characteristics of the base surface are not constant.

As shown in FIG. 7, the crack 104 has a shape like a V-shaped valley in a cross-sectional view. Due to the nature of the crack 104, the depth 104D tends to be longer (deeper) than the width 104W of the crack 104. As an example, when the width 104W is about 10 μm, the depth 104D is about 10 mm. When the width 104W of the V-shaped valley is narrow and the depth 104D is deep like the crack 104, when light is incident, it is absorbed while being reflected many times on both sides of the V-shaped valley. As a result, it is assumed that most of the light is not emitted to the outside of the surface to be inspected 102, and is apparently neither reflected nor scattered. However, when a narrow crack 104 having a width of 104 W is imaged by the camera 110 (see FIG. 1), it is assumed that the width of the image of the geometric crack 104 is smaller than the pixel size of the image sensor 111. In this case, the image of the crack 104 output as an image becomes brighter than it should be because the contrast is lowered by the ratio of the area of the image of the geometric crack 104 in the pixel to the area of the pixel. It is identified from the surrounding area. Therefore, the crack 104 is not completely dark, and is recognized as a decrease in brightness from the brightness around the crack 104.

FIG. 8 is a diagram showing a difference in the appearance of an image depending on the balance of luminance between brightfield illumination (illumination for reflected light) and darkfield illumination (illumination for diffused light) on the surface to be shown shown in FIG. In FIG. 8, the image 240A shows a state in which the brightness of the bright field illumination is too strong with respect to the brightness of the dark field illumination. The image 240B shows a state in which the brightness of the bright field illumination and the dark field illumination is well-balanced and the crack 104 is easily visible. The image 240C shows a state in which the brightness of the dark field illumination is too strong with respect to the brightness of the bright field illumination.

When the brightness of the bright field illumination is strong as in the image 240A, the reflective region 131 is bright and the diffusive region 131 is dark. In this case, it is difficult to distinguish the crack 104 from the region 131, and the visibility of the crack 104 is lowered. On the other hand, when the dark field illumination is strong as in the image 240C, the area 131 is dark and the area 132 is bright. In this case, it is difficult to distinguish between the crack 104 and the region 131, and the visibility of the crack 104 is lowered. In the case of the image 240B, the visibility of the crack 104 is improved by controlling the brightness of each of the bright field illumination and the dark field illumination independently of each other. In the example of the image 240B, the regions 131 and the regions 132 visually recognized in the images 240A and 240C are adjusted so as to have the same brightness as each other. In other words, the difference in brightness between the area 131 and the area 132 is adjusted to be small. As a result, the difference between the image of the crack 104 and the image of the other portion is clarified, and the visibility of the crack 104 is improved. Practically, the existence probability of the crack 104 is considered to be smaller than the existence probability of the region 131 and the region 132 having the smaller area. Therefore, in the above-mentioned adjustment of the brightness balance, the crack 104 is not adjusted so as not to be visible.

The image 240B in FIG. 8 shows an ideal state in which the brightness of the region 131 and the region 132 are exactly the same. However, as long as the crack 104 can be detected by visual or circuit detection processing and within the range where erroneous detection can be prevented or suppressed, even if there is a slight difference in the brightness of the region 131 and the region 132. good.

Adjustment of the brightness of each of the bright-field lighting and the dark-field lighting described above, in other words, adjustment of the brightness of the reflected light lighting unit (bright-field lighting) 210 and the diffused light lighting unit (dark-field lighting) 220 shown in FIG. Can be done manually, for example, by an operator. The operator, who is an inspection worker, adjusts the contrast of the image other than the crack 104 shown in FIG. 8 so as to be small while making full use of the image displayed on the display device 123 in real time. The state of the surface to be inspected 102 is unlikely to be uniform, and it is expected that it will be in various states if the inspection target changes. For example, if the entire surface 102 has a visual field range in which the reflective regions 132 shown in FIGS. 6 and 7 are almost nonexistent and most of them are diffusible regions 131, or vice versa, most of them are. It is conceivable that the region 132 is reflective. Further, when an image is taken on one test surface 102 in a plurality of visual field ranges and inspected, it is conceivable that the state of the test surface 102 differs depending on the visual field range. When the distribution of the reflective region 132 and the diffusive region 131 is biased on the surface to be inspected 102 in this way, as one aspect of the balance adjustment, the diffused light illuminating unit 220 and the reflected light illuminating unit 210 There may be an adjustment to turn on one of them and turn off the other.

<Automatic control of balance adjustment>
Next, a system that automatically adjusts the brightness balance using the image processing circuit shown in FIG. 1 will be described. FIG. 9 is an explanatory diagram showing a processing flow of a system that automatically adjusts the brightness of bright-field illumination and dark-field illumination. FIG. 10 is an explanatory diagram showing a configuration example of a computer that performs each step of the balance adjustment shown in FIG. The computer 125 shown in FIG. 10 is a device that constitutes a part of the inspection device 100 shown in FIG. 1, and is a luminance control unit (light intensity control unit) described with reference to the image processing circuit 122 shown in FIG. 1 and FIG. The 230 and the determination processing unit 126 for determining the necessity of changing the luminance in step S13 shown in FIG. 9 are provided. Each step will be described as a process performed by the computer 125 shown in FIG.

The luminance balancing system shown in FIG. 9 comprises steps S11, S12, S13, S14, and S15. In step S11, first, the luminance control unit 230 (see FIG. 10) of the computer 125 (FIG. 10) lights the diffused light illumination unit 220 (see FIG. 10), which is dark field illumination. In this state, the camera 110 shown in FIG. 1 takes an image within the visual field range of the surface to be inspected 102. In step S12 following step S11, the image processing circuit 122 of the computer 125 performs a two-dimensional Fourier transformation (FFT: Fast Fourier Transform) on the image data acquired from the image sensor 111, and performs a direct current (DC) component. And the brightness of the alternating current (AC) component other than the direct current component standardized by the brightness of the direct current component.

In step S13, the determination processing unit 126 (see FIG. 10) of the computer 125 divides the brightness of the AC component by the brightness of the DC component (hereinafter referred to as AC / DC) and sets a preset reference value. By comparison, it is determined whether or not the calculation result is less than the reference value. The determination processing unit 126 determines the brightness of the light emitted from the reflected light illumination unit 210 (see FIG. 10) and the diffused light illumination unit 220 (FIG. 1) based on the image data captured by the camera 110 (see FIG. 1). It has a function of determining whether or not it is necessary to change the brightness of at least one of the brightness of the light emitted from (see 10). In an example of the system shown in FIG. 9, the determination processing unit 126 determines whether or not the brightness of the light emitted from the reflected light illumination unit 210 needs to be changed. In the calculation of the FFT image in step S12, the spatial spectrum of the image is calculated. As illustrated in FIG. 6, when the diffusible region 131 and the reflective region 132 coexist on the test surface 102, the reference value is set so that the AC / DC becomes a value equal to or higher than the reference value.

When it is determined in step S13 that the AC / DC is equal to or higher than the reference value, the determination processing unit 126 of the computer 125 shown in FIG. 10 determines whether or not the luminance needs to be changed (change is required in the flow shown in FIG. 9). Data) is output to the luminance control unit 230. As step S14, the luminance control unit 230 of the computer 125 shown in FIG. 2 lights the reflected light illumination unit 210, which is the bright field illumination, based on the determination data transmitted from the determination processing unit 126. Alternatively, if the reflected light illumination unit 210 is already lit, the brightness of the reflected light illumination unit 210 is increased. Hereinafter, in step S13, the computer 125 repeatedly executes steps S12 to S14 until the AC / DC becomes less than the reference value.

If it is determined in step S13 that the AC / DC is less than the reference value, the brightness balance is adjusted. At this time, the determination processing unit 126 of the computer 125 shown in FIG. 10 outputs the above-mentioned determination processing data that does not require a change in luminance to the luminance control unit 230. Further, the determination processing unit 126 outputs the adjustment completion data to the image processing circuit 122. In step S15, the image processing circuit 122 of the computer 125 shown in FIG. 10 outputs the image data to the display device 123 shown in FIG. 1 based on the adjustment completion data received from the determination processing unit 126.

In FIG. 9, a method of adjusting the brightness of the bright-field illumination after turning on the dark-field illumination first has been exemplified, but as a modification, the bright-field illumination is turned on first and then dark. It can be a method of adjusting the brightness of the field illumination. Further, the brightness of the illumination lit in step S11 may be the maximum value, but may be about half to 70% of the maximum brightness. In this case, the feedback loop is used in the determination processing unit 126 of the computer 125 to change the brightness of either or both of the dark-field illumination and the bright-field illumination according to the AC / DC value subjected to the determination processing. In some cases, a method for constructing is used.

As described above, by automating the balance adjustment of the brightness of the bright field illumination and the dark field illumination, the work load of the operator who is an inspection worker can be reduced and the standard of the balance adjustment can be stabilized.

<Modification 1>
Next, a modification of the inspection device 100 shown in FIG. 1 will be described. FIG. 11 is a cross-sectional view of a main part schematically showing a configuration example of an inspection device which is a modification of FIG. 1. The inspection device 100A shown in FIG. 11 differs from the inspection device 100 shown in FIG. 1 in that the reflection mirror 114 is arranged in the path of light connecting the image sensor 111 and the lens 112. Further, in the case of the inspection device 100A, the detection light that has passed through the lens 112 is reflected by the reflection mirror 114 and received by the image sensor 111, which is different from the inspection device 100 shown in FIG.

Specifically, the camera 110 of the inspection device 100A includes a lens 112, which is an imaging lens, and an image sensor 111, which receives light (detection light) through the lens 112. A reflection mirror 114 is arranged in the path of light between the lens 112 and the image sensor 111. The image sensor 111 and the reflection mirror 114 are housed in a metal housing 106. The housing 106 is formed with an opening 106H to which the lens 112 is attached. The image sensor 111 is arranged at a position deviating from the extension line VL1 of the virtual line that linearly connects the opening 106H and the reflection mirror. The housing 106 has a bent shape, and the image sensor 111 is arranged at a position different from the extension line of the opening. In this case, even when the radiation in the reactor 101 enters the housing 106 through the opening 106H, it is possible to suppress the direct irradiation of the image sensor 111. Therefore, it is possible to suppress the failure or malfunction of the image sensor 111 due to the influence of radiation.

The inspection device 100A is the same as the inspection device 100 shown in FIG. 1, except for the above-mentioned differences. Therefore, duplicate explanations will be omitted. Although the reference numerals are omitted in FIG. 1, the housing 106 shown in FIG. 1 also has an opening 106H to which the lens 112 is attached, similar to the housing 106 shown in FIG. However, in the case of the inspection device 100, since there is no reflection mirror 114, the image sensor 111 is arranged on the extension line of the opening 106H. Therefore, the radiation that has entered through the opening 106H may be applied to the image sensor 111.

<Modification 2>
FIG. 12 is a cross-sectional view of a main part schematically showing a configuration example of an inspection device which is another modification to FIG. 1. FIG. 13 is an explanatory diagram schematically showing the path of the light emitted from the illuminated light unit for reflected light shown in FIG. 12, and FIG. 14 is a schematic diagram of the path of the light emitted from the illuminated unit for diffused light shown in FIG. It is explanatory drawing which shows. In this modification, an embodiment in which the optical axis 113 of the camera 110 is tilted with respect to the normal direction of the test surface 102 will be described.

The inspection device 100B shown in FIG. 12 has the inspection device 100 shown in FIG. 1 and the inspection device 100A shown in FIG. 11 in that the optical axis 113 of the camera 110 is inclined with respect to the normal direction of the surface to be inspected 102. Is different from. Further, in the inspection device 100B, the virtual image 254 of the light source (diffusing plate 253 regarded as a light source) of the reflected light illumination unit 250 having the inspected surface 102 as a virtual mirror surface is on the extension line of the optical axis 113 of the camera 110. It differs from the inspection device 100 shown in FIG. 1 and the inspection device 100A shown in FIG. 11 in that. In this way, the virtual image 254 of the diffuser plate 253, which is regarded as the light source of the light source for reflected light 250, which is the bright field illumination, is arranged on the extension line of the optical axis 113, so that the optical axis 113 and the surface to be inspected 102 It is possible to observe the vicinity of the intersection of the points with high accuracy as in other areas.

Specifically, the reflected light illumination unit 250 of the inspection device 100B includes an LED array 251, a cylindrical lens 252, and a diffuser plate 253. The LED array 251 is a light source that generates light, and is a semiconductor component in which a plurality of LED (Light Emitting Diode) elements are arranged. The plurality of LED elements are arranged in a direction perpendicular to the paper surface of FIG. The cylindrical lens 252 is an optical element that converts the light received from the LED array 251 into a sheet beam. The cylindrical lens 252 has a longitudinal direction in the direction perpendicular to the paper surface of FIG. 12, and can convert the light received from the LED array 251 into a sheet beam parallel to the in-paper direction. The diffuser plate 253 is a surface light source that receives a sheet beam emitted from the cylindrical lens 252 and irradiates light over a wide range. Since the light from the diffuser plate 253 is irradiated to the surface to be inspected 102, the light source of the light reflecting light unit 250 for inspecting the surface to be inspected 102 can be regarded as the diffuser plate 253. ..

As shown in FIG. 13, the light emitted from the LED array 251 irradiates the diffuser plate 253 via the cylindrical lens 252, and the light emitted from the diffuser plate 253 illuminates the surface to be inspected 102. At least a part of the light specularly reflected by the surface 102 to be inspected is received by the image sensor 111 via the lens 112 and the reflection mirror 114. A phase plate 115 for WFC (Wave Front Cording), which will be described later, is arranged between the lens 112 and the reflection mirror 114. Similar to the case of the inspection device 100 shown in FIG. 1, in the case of the inspection device 100B, the virtual image 254 of the light source (diffusing plate 253) of the reflected light illumination unit 250 having the test surface 102 as a virtual mirror surface is the camera 110. Is within the viewing range 105 (see FIG. 12). Therefore, at least a part of the light specularly reflected by the surface 102 to be inspected is received by the lens 112.

Further, the diffused light illumination unit 260 includes an LED array 261 and a cylindrical lens 262. The plurality of LED elements included in the LED array 261 are arranged in a direction perpendicular to the paper surface of FIG. The cylindrical lens 262 is an optical element that converts the light received from the LED array 261 into a sheet beam. The cylindrical lens 262 has a longitudinal direction in the direction perpendicular to the paper surface of FIG. 12, and can convert the light received from the LED array 261 into a sheet beam parallel to the in-paper direction. In the case of light for diffuse light, which is dark field illumination, the light emitted from the cylindrical lens 262 is applied to the surface to be inspected 102 as shown in FIG. Therefore, the cylindrical lens 262 can be regarded as a light source of the diffused light illumination unit 260. Similar to the case of the inspection device 100 shown in FIG. 1, in the case of the inspection device 100B, the virtual image 264 of the light source (cylindrical lens 262) of the diffused light illumination unit 260 having the inspected surface 102 as a virtual mirror surface is the camera 110. Does not exist within the field of view 105 (see FIG. 12), but is outside the field of view 105. Therefore, regarding the light emitted from the diffused light illumination unit 260, the light normally reflected by the subject surface 102 is not received by the lens 112, and a part of the light diffused by the subject surface 102 is transmitted to the lens 112. The light is received by the image sensor 111 via the lens 112 and the reflection mirror 114.

As described above, in the case of this modification, the optical axis 113 of the camera 110 is arranged so as to be inclined with respect to the normal direction of the surface to be inspected 102, so that the virtual image 254 of the diffuser plate 253 is optical axis. It can be arranged on the extension line of 113. As a result, the central region near the point where the optical axis 113 of the camera 110 and the surface to be inspected 102 intersect can be observed with high accuracy. However, in the case of this modification, there arises a problem that the focus range of the test surface 102 becomes narrow due to the fact that the optical axis 113 is inclined with respect to the normal direction of the test surface 102. .. Although it is not impossible to focus even if the focus range is narrowed, it is preferable to apply the technique of the imaging system called WFC described below.

In the imaging system using WFC, the blur of the point image due to the defocus is made uniform by giving the phase distribution given by the cubic function to the coordinates in the pupil plane, and the uniform blur is made by image processing called deconvolution. Remove and increase the depth of field and depth of focus of the optical system. To apply this technique, the inspection device 100B of this modification has a phase plate 115 arranged between the lens 112 and the reflection mirror 114. The phase plate 115 is arranged at the position of the diaphragm of the imaging optical system. The position of the phase plate 115 may be close to the position of the diaphragm. The phase plate 115 is a phase filter having a surface represented by a cubic function. In the example shown in FIG. 12, the phase plate 115 has a shape in which a plurality of concave surfaces are arranged concentrically around the optical axis 113. The phase plate 115 has a shape to be rotated around the optical axis 113. Each of the plurality of concave surfaces forms a parabolic cross-sectional shape. A structure in which a plurality of concave surfaces forming a cross-sectional shape of a parabola are arranged in this way is called an annular structure. The part corresponding to one of the plurality of concave surfaces is called a ring band.

In FIG. 12, the phase plate 115 having a ring-shaped structure is illustrated as described above, but there are various modifications of the phase plate 115 applicable to WFC. As long as it is a curved surface that can be represented by a cubic function, it may have a structure other than the annular structure. Alternatively, as long as it is a curved surface that causes spherical aberration, it may have a structure other than the annular structure.

When the light reflected or diffused by the surface to be inspected 102 is received by the image sensor 111 via the phase plate 115, the image on the image sensor 111 is blurred. In other words, the image data output by the image sensor 111 is an optical image that is out of focus. However, the phase plate 115 is designed so that the blurring of the image on the image sensor 111 becomes insensitive to defocus. By designing the phase plate 115 so as to be insensitive to defocus, it is possible to solve the above-mentioned problem that the focus range is narrowed. That is, by interposing the phase plate 115 in the path of light in the camera 110, the blurring of the image in the image sensor 111 becomes uniform regardless of the degree of defocus. In this case, by executing the deconvolution process described later, it is possible to acquire an image without blur (the crack 104 shown in FIG. 8 is less blurred to the extent that it can be identified).

The image processing circuit 122 shown in FIG. 12 executes deconvolution processing for acquiring a focused image from a blurred optical image with respect to the image data (blurred image data) received from the image sensor 111. The deconvolution process is an arithmetic process for calculating a geometric map (ideal optical image) of the light intensity distribution on the object surface on the image plane from the spatial frequency spectrum (which is the optical transfer function OTF) of the point image distribution. Although details are omitted, deconvolution processing and WFC processing using the deconvolution processing are described in detail as deconvolution image processing in the patent document (public relations company No. 2014-197115) by the inventors of the present application. There is. The image processing circuit 122 performs deconvolution image processing described in this patent document.

After the deconvolution processing is completed, the image processing circuit 122 outputs the image data (image data from which the blur has been removed) after the deconvolution processing to the display device 123. As a result, the display device 123 displays an image from which the blur has been removed, and the crack 104 shown in FIG. 8 can be detected based on this image. The inspection device 100B is the same as the inspection device 100 shown in FIG. 1, except for the above-mentioned differences. Therefore, duplicate explanations will be omitted. Although not shown, the brightness of each of the reflected light illumination unit 250 and the diffused light illumination unit 260 can be controlled independently by the luminance control unit 230 shown in FIG. 2. It is the same as the inspection apparatus 100 shown in 1.

In the above, various modification examples have been described, but each modification example can be appropriately combined and applied.

Although the typical modifications of the present embodiment have been described above, the present invention is not limited to the above-mentioned examples and typical modifications, and various modifications can be made without departing from the spirit of the invention. Applicable.

The present invention can be used for a lighting device and an inspection device using the lighting device.

100, 100A, 100B Inspection equipment 101 Reactor (container)
102 Inspected surface (inspected surface)
104 Rhagades 104W Width 104D Depth 105 Field of view 106 Housing 106H Aperture 110 Camera 111 Image sensor 112 Lens (imaging lens)
113 Optical axis 114 Reflection mirror 115 Phase plate 120 Transmission circuit 121 Cable 122 Image processing circuit 123 Display device 125 Computer 126 Judgment processing unit 131, 132 Area 200 Lighting device (illumination unit)
210,250 Illumination unit for reflected light (bright-field lighting, bright-field lighting unit)
211,221,254,264 Virtual image 212,222 Cable 213,223 Light 220,260 Diffuse light illumination unit (dark field illumination, dark field illumination unit)
230 Luminance control unit (light intensity control unit)
240A, 240B, 240C Image 251,261 LED array 252,262 Cylindrical lens 253 Diffusing plate S11, S12, S13, S14, S15 Step VL1 extension line

Claims (7)

An illuminating unit for reflected light that is reflected by the surface to be inspected and irradiates the light incident on the camera.
A diffused light illuminating unit that diffuses on the surface to be inspected and irradiates the light incident on the camera.
Have,
A virtual image of the light source of the light source for reflected light having the surface to be inspected as a virtual mirror surface is within the visual field range of the camera.
A lighting device in which a virtual image of a light source of the diffused light lighting unit having the surface to be inspected as a virtual mirror surface is not within the field of view of the camera. A camera that captures the surface to be inspected and
An illuminating unit for reflected light that is reflected by the surface to be inspected and irradiates light incident on the camera.
A diffused light illuminating unit that diffuses on the surface to be inspected and irradiates the light incident on the camera.
Have,
A virtual image of the light source of the light source for reflected light having the surface to be inspected as a virtual mirror surface is within the visual field range of the camera.
An inspection device in which a virtual image of a light source of the diffused light illumination unit having the surface to be inspected as a virtual mirror surface is not within the field of view of the camera. In the inspection device according to claim 2,
An inspection device further comprising a luminance control unit that controls each of the luminance of the light emitted from the reflected light illumination unit and the luminance of the light emitted from the diffused light illumination unit. In the inspection device according to claim 3,
Whether or not it is necessary to change the brightness of at least one of the brightness of the light emitted from the reflected light illumination unit and the brightness of the light emitted from the diffused light illumination unit based on the image data captured by the camera. Further has a determination processing unit for determining
The determination processing unit is an inspection device that outputs the determination processing data of the necessity of change to the luminance control unit. In the inspection device according to claim 4,
The optical axis of the camera is tilted with respect to the normal direction of the surface to be inspected.
An inspection device whose virtual image of the light source of the reflected light illumination unit having the surface to be inspected as a virtual mirror surface is on an extension of the optical axis of the camera. In the inspection device according to claim 5,
It further has an image processing circuit that processes the image data captured by the camera.
The camera
Imaging lens and
An image sensor that receives light through the imaging lens and
Equipped with
A reflection mirror is placed in the path of light between the imaging lens and the image sensor.
A phase plate is arranged between the reflection mirror and the imaging lens.
The image data output by the image sensor is an optical image that is out of focus.
The image processing circuit executes deconvolution processing for acquiring a focused image from the blurred optical image with respect to the image data received from the image sensor, and outputs the image data after the deconvolution processing. Inspection equipment. In the inspection device according to claim 4,
The camera
Imaging lens and
An image sensor that receives light through the imaging lens and
Equipped with
A reflection mirror is placed in the path of light between the imaging lens and the image sensor.
The image sensor and the reflection mirror are housed in a metal housing.
An opening for attaching the imaging lens is formed in the housing.
The image sensor is an inspection device arranged at a position deviating from an extension of a virtual line linearly connecting the opening and the reflection mirror.

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