Optical inspection apparatus, optical inspection system, optical inspection method, and optical inspection program

Abstract

To provide an optical inspection apparatus which can acquire information of a surface of an object including a curved surface, or the like.SOLUTION: An optical inspection apparatus includes an illumination portion, a wavelength selection portion and an imaging portion. The illumination portion irradiates a first object point of a surface of an object with first illumination light, and a second object point of the surface of the object with second illumination light, the second object point having a normal direction different from a normal direction at the first object point, with the second illumination light having a direction different from that of the first illumination light. The wavelength selection portion includes at least two wavelength selection regions that selectively transmit light having different wavelength spectra. The imaging portion is configured to: image light from the first object point through the wavelength selection portion when a normal direction at the first object point and a direction of the first illumination light have an opposing relationship, and image light from the second object point through the wavelength selection portion when a normal direction at the second object point and a direction of the second illumination light have an opposing relationship. The wavelength selection portion is arranged between the imaging portion and the surface of the object.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to an optical inspection apparatus, an optical inspection system, an optical inspection method, and an optical inspection program.

Background Art

[0002] In various industries, non-contact surface measurement of an object has become important. In a conventional method, there is a technique of splitting light rays to illuminate an object, acquiring images split by a pixel device, and estimating each light ray direction to acquire information on the object surface.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem that this invention aims to solve is to provide an optical inspection device, an optical inspection system, an optical inspection method, and an optical inspection program that can acquire information about the surface of an object, including curved surfaces. [Means for solving the problem]

[0006] According to the embodiment, the optical inspection apparatus comprises an illumination unit, a wavelength selection unit, and an imaging unit. The illumination unit irradiates a first object point on the surface of an object with a first illumination light, and irradiates a second object point on the surface of the object, which has a normal direction different from the normal direction of the first object point, with a second illumination light in a direction different from the first illumination light. The wavelength selection unit has at least two wavelength selection regions that selectively pass light of different wavelength spectra. The imaging unit comprises an imaging optical element and an image sensor positioned on the image plane of the imaging optical element, with a wavelength selection unit positioned between the imaging optical element and the surface of the object. When the normal direction at the first object point is opposite to the direction of the first illumination light, the imaging unit selects the light from the first object point into the wavelength selection unit. imaging optical element of in order Through Image sensor Imaging is possible. When the normal direction at the second object point is opposite to the direction of the second illumination light, the imaging unit selects the light from the second object point using the wavelength selection unit. imaging optical element of in order Through Image sensor Imaging is possible. 。 [Brief explanation of the drawing]

[0007] [Figure 1] A schematic diagram showing an optical inspection system according to the first embodiment. [Figure 2] A schematic block diagram of the processing unit of the optical inspection system shown in Figure 1. [Figure 3] A flowchart illustrating the processing flow of the processing unit of the optical inspection system shown in Figure 1. [Figure 4] A schematic diagram showing an optical inspection system according to a first modification of the first embodiment. [Figure 5] A schematic diagram showing an optical inspection system according to a second modification of the first embodiment. [Figure 6] A schematic diagram showing an optical inspection system according to the second embodiment. [Figure 7]In the optical inspection system shown in FIG. 6, a schematic diagram showing the relationship between a cross-sectional view of an object being conveyed in the conveyance direction at a certain time, illumination light, and BRDF. [Figure 8] A schematic diagram of an image captured by the imaging unit at the time shown in FIG. 7. [Figure 9] In the optical inspection system shown in FIG. 6, a schematic diagram showing the relationship between a cross-sectional view of an object being conveyed in the conveyance direction at a time later than the time shown in FIG. 7, illumination light, and BRDF. [Figure 10] A schematic diagram of an image captured by the imaging unit at the time shown in FIG. 9. [Figure 11] An example of an image including three object points of an object photographed using the optical inspection system shown in FIG. 6 and the vicinity thereof. [Figure 12] An example of a wavelength selection unit. [Figure 13] An example of a wavelength selection unit. [Figure 14] An example of a wavelength selection unit. [Figure 15] An example of a wavelength selection unit. [Figure 16] A schematic diagram showing an optical inspection system according to the third embodiment.

Embodiments for Carrying Out the Invention

[0008] Hereinafter, each embodiment will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationships between the thickness and width of each part, the ratios of the sizes between parts, etc. are not necessarily the same as those in reality. Also, even when representing the same part, the dimensions and ratios may be represented differently in the drawings. In the present specification and each figure, the same elements as those described above with respect to the previously shown figures are denoted by the same reference numerals, and detailed descriptions thereof are omitted as appropriate.

[0009] (First Embodiment) Hereinafter, the optical inspection system 10 according to the present embodiment will be described with reference to FIGS. 1 to 3.

[0010] In this specification, light is a type of electromagnetic wave, including X-rays, ultraviolet rays, visible light, infrared rays, microwaves, etc. In this embodiment, it is assumed that the light is visible light, and for example, the wavelength is in the range of 400 nm to 750 nm. The imaging unit 24 is composed of an imaging optical element 42 having an optical axis and a sensor (image sensor) 44.

[0011] FIG. 1 shows a schematic cross-sectional view of the optical inspection device 12 of the optical inspection system 10 of this embodiment and the processing device 14. It is assumed that this cross-sectional view is on the x-z plane.

[0012] The optical inspection device 12 according to this embodiment includes an illumination unit 22, an imaging unit 24, and a wavelength selection unit 26.

[0013] The illumination unit 22 emits a first illumination light L1 and a second illumination light L2. It is assumed that both the first illumination light L1 and the second illumination light L2 are white light. It is assumed that the wavelength spectrum of any of the illumination lights L1 and L2 has a significant intensity distribution between 400 nm and 750 nm. The first illumination light L1 and the second illumination light L2 are each substantially parallel light, and their directions are different from each other. Also, the light source of the illumination light may be anything, but here a white LED is used as the light source.

[0014] In FIG. 1, the illumination unit 22 is provided between the surface of the object S and the wavelength selection unit 26, but the light source of the illumination unit 22 does not have to be between the surface of the object S and the wavelength selection unit 26. In this case, for example, the first illumination light L1 and the second illumination light L2 are irradiated onto the surface of the object S through a half mirror, a beam splitter, a mirror, etc.

[0015] The imaging unit 24 includes an imaging optical element 42 and an image sensor (sensor) 44.

[0016] The imaging optical element 42 is, for example, an imaging lens. In Figure 1, the imaging lens is schematically represented by a single lens, but it may also be a lens assembly composed of multiple lenses. Alternatively, the imaging optical element 42 may be a concave mirror, a convex mirror, or a combination thereof. In other words, the imaging optical element 42 can be any optical element that has the function of focusing a group of light rays emitted from a single point on the object S, i.e., the object point, to its conjugate image point. The process by which the imaging optical element 42 focuses (concentrates) a group of light rays emitted from an object point on the surface of the object S to the image point is called imaging. Alternatively, it can be said that the object point is moved to the image point (the conjugate point of the object point). The plane of conjugate points to which a group of light rays emitted from a sufficiently distant object point are moved by the imaging optical element 42 is called the focal plane of the imaging optical element 42. The optical axis is a line perpendicular to the focal plane that passes through the center of the imaging optical element. In this case, the conjugate image point of the object point projected by this light ray is called the focal point. In this embodiment, the imaging optical element 42 is simply called a lens.

[0017] An xyz Cartesian coordinate system is defined for the optical inspection apparatus 12 shown in Figure 1. As shown in Figure 1, the xz plane is used. Although not shown, the y-axis is perpendicular to the x-axis and z-axis. In the cross-section shown in Figure 1, the optical axis is defined as the z-axis.

[0018] The wavelength selection unit 26 is positioned between the imaging unit 24 and the surface of the object S. The wavelength selection unit 26 has at least two or more wavelength selection regions 52, 54. Two of these wavelength selection regions are designated as the first wavelength selection region 52 and the second wavelength selection region 54. The direction in which the first wavelength selection region 52 and the second wavelength selection region 54 are aligned is along the x-axis. In other words, the first wavelength selection region 52 and the second wavelength selection region 54 intersect the x-axis. The direction in which the first wavelength selection region 52 and the second wavelength selection region 54 extend is along the y-axis. In other words, the first wavelength selection region 52 and the second wavelength selection region 54 extend along the y-axis. However, this is not limited to the first wavelength selection region 52 or the second wavelength selection region 54, which may intersect the y-axis.

[0019] The first wavelength-selective region 52 allows light rays having a wavelength spectrum including the first wavelength to pass through. Here, allowing light rays to pass through means directing the light rays from the object point to the image point by transmission or reflection. On the other hand, the first wavelength-selective region substantially shields light rays of the second wavelength. Here, shielding means not allowing the light rays to pass through. In other words, it means not directing the light rays from the object point to the image point. The second wavelength-selective region 54 allows light rays of the second wavelength to pass through. On the other hand, it substantially shields light rays of the first wavelength. Therefore, the wavelength-selective regions 52 and 54 of the wavelength-selective unit 26 selectively allow light with at least two different wavelength spectra to pass through.

[0020] For example, the first wavelength might be 450 nm blue light, and the second wavelength might be 650 nm red light. However, the wavelengths are not limited to these; any wavelengths can be used.

[0021] The image sensor 44 has at least one pixel, and each pixel is capable of receiving at least two different wavelengths of light, namely a first wavelength and a second wavelength. The plane containing the region on which the sensor 44 is located is the image plane of the imaging optical element 42. The image sensor 44 may be an area sensor or a line sensor. An area sensor has pixels arranged in an area shape within the same plane. A line sensor has pixels arranged in a line shape. Each pixel may also have three color channels: R, G, and B. In this embodiment, the sensor 44 is an area sensor, and each pixel has two color channels: red and blue. That is, it is capable of receiving blue light with a wavelength of 450 nm and red light with a wavelength of 650 nm in independent color channels. However, each color channel does not need to be completely independent; in practice, any color channel may have slight sensitivity to wavelengths other than those to which it is highly sensitive.

[0022] The directional distribution of reflected light from a point on the surface of object S can be represented by a distribution function called BRDF (Bidirectional Reflectance Distribution Function). Generally, BRDF changes depending on the surface properties and shape. For example, if the surface is rough, the reflected light spreads in various directions, resulting in a broad BRDF distribution. In other words, reflected light exists over a wide range of angles. On the other hand, if the surface of object S is mirror-like, the reflected light consists almost entirely of specular reflection, resulting in a narrow BRDF distribution. Thus, BRDF reflects the surface properties and micro-shape of object S. Here, surface properties and micro-shape can refer to surface roughness, or to minute irregularities that are close in size to or smaller than the wavelength of light (i.e., tens of times the wavelength or less). In this embodiment, since the light is visible light, anything relating to the surface height distribution of tens of micrometers or less is acceptable.

[0023] The processing unit 14 is connected to the optical inspection device 12. The processing unit 14 includes, for example, a processor 61 (control unit), a ROM (storage unit) 62, a RAM 63, an auxiliary storage device 64 (storage unit), a communication interface 65 (communication unit), and an input unit 66.

[0024] The processor 61 is the central part of the computer that performs calculations and control necessary for the processing of the processing unit 14, and comprehensively controls the entire processing unit 14. Based on programs such as system software, application software, or firmware stored in a storage unit such as ROM 62 or auxiliary storage device 64, the processor 61 executes control to realize various functions of the processing unit 14. The processor 61 includes, for example, a CPU (central processing unit), MPU (micro processing unit), DSP (digital signal processor), ASIC (Application Specific Integrated Circuit), or FPGA (Field Programmable Gate Array). Alternatively, the processor 61 is a combination of several of these. The processing unit 14 may have one processor 61 or multiple processors 61.

[0025] ROM62 corresponds to the main memory of a computer centered around the processor 61. ROM62 is a non-volatile memory used exclusively for reading data. ROM62 stores the program described above. Furthermore, ROM62 stores data or various settings used by the processor 61 in performing various processes.

[0026] RAM63 corresponds to the main memory of a computer centered around the processor 61. RAM63 is memory used for reading and writing data. RAM63 is used as a so-called work area, where data temporarily used by the processor 61 during various processes is stored.

[0027] The auxiliary storage device 64 corresponds to the auxiliary storage device of a computer centered on the processor 61. The auxiliary storage device 64 is, for example, an EEPROM (electrically erasable programmable read-only memory) (registered trademark), an HDD (hard disk drive), or an SSD (solid state drive). The auxiliary storage device 64 may also store the above-mentioned programs. In addition, the auxiliary storage device 64 stores data used by the processor 61 in performing various processes, data generated by processing by the processor 61, or various setting values.

[0028] The program stored in the ROM 62 or auxiliary storage device 64 includes a program for controlling the processing unit 14. For example, an optical inspection program is preferably stored in the ROM 62 or auxiliary storage device 64.

[0029] The communication interface 65 is an interface for communicating with other devices via a network or the like, either by wire or wireless connection, receiving various information transmitted from other devices, and transmitting various information to other devices. The processing unit 14 acquires image data obtained by the image sensor 44 via the communication interface 65.

[0030] The processing unit 14 preferably includes an input unit 66, such as a keyboard, for inputting the arrangement and type of the wavelength selection unit 26. The input unit 66 may also be capable of receiving various types of information wirelessly from the processor 61 via a communication interface 65.

[0031] The processing unit 14 performs various functions by causing the processor 61 to execute programs stored in the ROM 62 and / or auxiliary storage device 64, etc. It is also preferable that the control program of the processing unit 14 is not stored in the ROM 62 and / or auxiliary storage device 64 of the processing unit 14, but is instead located on an appropriate server or cloud. In this case, the control program is executed while communicating with the processor 61 of, for example, the optical inspection system 10 via the communication interface 65. That is, the processing unit 14 according to this embodiment may be part of the optical inspection system 10, or it may be located on a server or cloud of a system in various inspection facilities, separate from the optical inspection system. Therefore, it is also preferable that the optical inspection program resides on a server or cloud, rather than being stored in the ROM 62 or auxiliary storage device 64, and that the program is executed while communicating with the processor 61 of, for example, the optical inspection system 10 via the communication interface 65. Consequently, the processor 61 (processing unit 14) can execute the optical inspection program (optical inspection algorithm) described later.

[0032] The processor 61 (processing unit 14) controls the timing of light emission from the light source of the illumination unit 22, the timing of image data acquisition by the image sensor 44, and the acquisition of image data from the image sensor 44.

[0033] Based on the above configuration, the operating principle of the optical inspection system 10 of this embodiment will now be described.

[0034] In Figure 1, assume that the first object point O1 is a mirror surface, and the second object point O2 has micron-sized surface defects close to the wavelength of light. In this case, the BRDF at the first object point O1 has a narrow distribution. On the other hand, the BRDF at the second object point O2 has a broad distribution. In other words, the first object point O1 and the second object point O2 have different BRDFs.

[0035] The first illumination light L1 causes reflected light to be generated from the first object point O1. The reflected light from the first object point O1 passes only through the first wavelength selection region 52 of the wavelength selection unit 26, and becomes blue light having a wavelength spectrum, for example, from 430 nm to 480 nm.

[0036] The second illumination light L2 causes reflected light to be generated from the second object point O2. The reflected light from the second object point O2 passes through both the first wavelength selection region 52 and the second wavelength selection region 54 of the wavelength selection unit 26. The light that passes through the first wavelength selection region 52 becomes blue light with a wavelength spectrum from 430 nm to 480 nm. The light that passes through the second wavelength selection region 54 becomes red light with a wavelength spectrum, for example, from 620 nm to 680 nm. Of the reflected light from the second object point O2, the light of the second wavelength incident on the first wavelength selection region 52 is blocked, and the light of the first wavelength incident on the second wavelength selection region 54 is blocked.

[0037] If the reflected light from the first object point O1 can reach the imaging optical element 42, the first object point O1 is mapped to the first image point I1 by the imaging optical element 42. In this embodiment, the reflected light from the second object point O2 reaches the imaging optical element 42 and is mapped to the second image point I2.

[0038] However, if the first illumination light L1 is directed in the same direction as the second illumination light L2, the reflected light from the first object point O1 cannot reach the imaging optical element 42. This is because the normal directions of the surface of object S at the first object point O1 and the second object point O2 are different, and the reflection direction is determined according to the illumination direction and the normal direction. In other words, unless the direction of the illumination light is appropriately set according to the normal direction of the surface of object S, the reflected light cannot reach the imaging optical element 42. If the reflected light does not reach the imaging optical element 42, the first object point O1 will not be captured in the image. In other words, if the reflected light from the first object point O1 does not reach the imaging optical element 42, the surface state of the first object point O1 cannot be inspected.

[0039] The second object point O2 is projected onto the second image point I2 by the lens. However, if the second illumination light is directed in the same direction as the first illumination light L1, the reflected light from the second object point O2 cannot reach the imaging optical element 42. This is because the normal directions of the surface of object S at the first object point O1 and the second object point O2 are different, and the reflection direction is determined according to the illumination direction and the normal direction. In other words, unless the direction of the illumination light is appropriately set according to the normal direction of the surface of object S, the reflected light cannot reach the lens. If the reflected light does not reach the imaging optical element 42, the second object point O2 will not be captured in the image. In other words, if the reflected light from the second object point O2 does not reach the imaging optical element 42, the state of the surface S of the second object point O2 cannot be inspected.

[0040] As described above, by illuminating a first object point O1 and a second object point O2, which have different normal directions, with a first illumination light L1 and a second illumination light L2, which have different directions, both can be simultaneously captured and acquired as images (S101). On the other hand, if the first illumination light L1 and the second illumination light L2 are in the same direction, it is not possible to capture both as images simultaneously.

[0041] The first image point I1 and the second image point I2 are essentially on the area sensor 44. The acquired image obtained by the area sensor 44 is sent to the processing unit 14 as an electrical signal. At the first image point I1, only blue light is received by the area sensor 44. Therefore, the processing unit 14 recognizes that light has passed through one type of wavelength selection region 52. On the other hand, at the second image point I2, both blue and red light are received simultaneously. Therefore, the processing unit 14 recognizes that light has passed through two types of wavelength selection regions 52 and 54. This process of estimating the number of colors is called the color number estimation process. The color number estimation process allows the number of colors (number of colors) received at each image point I1 and I2 to be obtained (S102).

[0042] The number of colors can be estimated by the relative ratio of the pixel values ​​of each color channel in any given pixel. For example, if only blue light is received by any pixel, the pixel value of the blue channel will be large, and the pixel value of the red channel will be almost 0. In this case, the intensity of the red channel is relatively small compared to the blue channel. On the other hand, if both blue and red light are received by any pixel simultaneously, the pixel value of the blue channel will be large, and the pixel value of the red channel will also be large. In this case, the intensity of the red channel is relatively about the same as that of the blue channel. Furthermore, if only red light is received by any pixel, the pixel value of the red channel will be large, and the pixel value of the blue channel will be almost 0. In this case, the intensity of the blue channel is relatively small compared to the red channel. As described above, the number of colors can be estimated by the relative ratio of the pixel values ​​of each color channel in each pixel.

[0043] However, there are various methods for counting the number of colors, depending on how background noise (such as dark current noise and the spectral performance of the sensor and wavelength-selective region) is set. For example, depending on the spectral performance of the image sensor 44, an electrical signal corresponding to green light may be triggered by red light even if green light has not reached the sensor 44. Therefore, calibration is performed to correlate the number of colors with the number of wavelength-selective regions 52 and 54 through which the light rays have passed, by offsetting the background noise. In addition, it is advisable to set an appropriate threshold for the pixel value to distinguish between background noise and the desired signal. By performing such calibration and setting the threshold, an accurate number of colors can be obtained.

[0044] Light reflected in various directions due to the surface properties and microscopic shape of an object S is generally called scattered light. As already mentioned above, the degree of spread of the scattered light distribution can be represented by the BRDF. Furthermore, it is thought that a BRDF with a large number of colors is spread out, and the BRDF becomes narrower as the number of colors decreases. In other words, if the number of colors at each image point can be obtained by the color number estimation process, the differences in BRDF at each object point can be identified. As a result, an image can be obtained by capturing light from an object S that has passed through a wavelength selection unit 26 having at least two different wavelength selection regions 52, 54, and a color number estimation process is performed to estimate the number of wavelength selection regions 52, 54 that the light has passed through from that image, the number of colors can be obtained, and the directional distribution of scattered light from the surface of the object S can be identified based on the number of colors (S103). Since the BRDF is correlated with the properties and microscopic shape of the surface S, this embodiment has the effect of being able to identify the differences in the properties and microscopic shape of the surface S of each object point O1, O2 on the surface of the object S. This makes it possible to identify the properties and micro-shape (state of surface S) of the surface S without contact, without spectrally separating the illumination (S104).

[0045] The color number estimation process described above has the effect of being independent of the normal direction of the surface of object S. This is because, firstly, the extent of the BRDF depends on the surface properties and minute shapes of object S, and not on the normal direction. Furthermore, the number of colors depends on the extent of the BRDF, and not on the normal direction. In other words, even if the surface of object S is curved, this embodiment has the effect of being able to inspect and identify the surface properties and minute shapes of object S.

[0046] Furthermore, this embodiment has the effect of simultaneously acquiring images of two object points O1 and O2 with different normal directions, and their vicinity, when the surface of object S is a curved surface or the like. This is because the directions of the illuminations are different, such as the first illumination light L1 and the second illumination light L2. On the other hand, if the directions of the first illumination light L1 and the second illumination light L2 are the same, it is not possible to simultaneously image the first object point O1, the second object point O2, and their vicinity. In other words, either the first object point O1 or the second object point O2 will not be brightly captured and will appear dark.

[0047] In this embodiment, the first image point I1 has a color number of 1, and the second image point I2 has a color number of 2. This has the effect of allowing us to distinguish that the BRDF is different between the first object point O1 and the second object point O2 on the surface of object S. In other words, it has the effect of allowing us to distinguish the differences in the properties and minute shapes of the surface S of each object point O1 and O2.

[0048] As described above, this embodiment provides an optical inspection device 12, an optical inspection system 10, an optical inspection method, and an optical inspection program that can acquire information about the surface of an object S, including curved surfaces.

[0049] (First variation) Figure 4 shows a modified example of the optical inspection system 10 according to the first embodiment. In the optical inspection device 12 shown in Figure 4, the illumination unit 22 is not shown.

[0050] As shown in Figure 4, the wavelength selection unit 26 includes a third wavelength selection region 56 in addition to the first wavelength selection region 52 and the second wavelength selection region 54. At this time, the reflected light from the second object point O2 passes through the third wavelength selection region 56 of the wavelength selection unit and becomes green light having a spectrum from wavelength 520 nm to wavelength 580 nm, for example. The green light is projected from the second object point O2 to the second image point. As a result, the number of colors at the second image point becomes 3 through the color number estimation process. On the other hand, the number of colors at the first object point O1 is 1. This makes the difference in the number of colors between the first object point O1 and the second object point O2 even clearer, which has the effect of enabling highly accurate optical inspection. It also has the effect of allowing for a more detailed understanding of the BRDF distribution at the second object point O2. In other words, it has the effect of being able to distinguish that the BRDF is different when the number of colors is 2 and when it is 3.

[0051] Therefore, according to this modified version, it is possible to provide an optical inspection device 12, an optical inspection system 10, an optical inspection method, and an optical inspection program that can acquire information about the surface of an object S, including curved surfaces.

[0052] (Second variation) Figure 5 shows a modified example of the optical inspection system 10 according to the first embodiment. In the optical inspection device 12 shown in Figure 5, the illumination unit 22 is not shown.

[0053] As shown in Figure 5, the wavelength selection region of the wavelength selection unit 26 can be used repeatedly. The wavelength selection unit 26 has at least two other wavelength selection regions 52, 54 that have the same wavelength spectral characteristics as at least two wavelength selection regions 52, 54. For example, along the x-axis, they are arranged in the order of first wavelength selection region 52, second wavelength selection region 54, first wavelength selection region 52, second wavelength selection region 54. Each wavelength selection region 52, 54 extends parallel to the y-axis. Therefore, the wavelength selection unit 26 has two pairs of wavelength selection regions 52, 54 aligned in the x-axis direction.

[0054] Even in this way, the number of colors at the first image point I1 is 1, and the number of colors at the second image point I2 is 2, resulting in a difference in the number of colors. Therefore, it is possible to distinguish the difference in BRDF between the first object point O1 and the second object point O2, which are corresponding object points. Furthermore, by narrowing the region width of pairs of the same wavelength selection regions 52 and 54 and using them repeatedly, the inspection accuracy can be improved. In other words, by narrowing the region width of each wavelength selection region 52 and 54 of the wavelength selection unit 26, the sensitivity to the spread of the BRDF can be improved. This is because by narrowing the region width, the number of colors changes for smaller spreads of the BRDF. As described above, by repeatedly arranging the wavelength selection regions 52 and 54, the accuracy can be improved.

[0055] However, when the wavelength-selective regions 52 and 54 are arranged repeatedly, two adjacent wavelength-selective regions 52 and 54 must be different from each other. In other words, by having different transmission and shielding wavelengths for two adjacent wavelength-selective regions 52 and 54, the extent of the BRDF can be identified by the number of colors.

[0056] In Figure 5, the two wavelength-selective regions 52 and 54 are described as a single pair, but it is also possible to arrange the three wavelength-selective regions 52, 54, and 56 as a single pair, repeating the order of wavelength-selective regions 52, 54, and 56.

[0057] Therefore, according to this modified version, it is possible to provide an optical inspection device 12, an optical inspection system 10, an optical inspection method, and an optical inspection program that can acquire information about the surface of an object S, including curved surfaces.

[0058] (Second Embodiment) The optical inspection system 10 according to this embodiment will be described with reference to Figure 6.

[0059] Figure 6 shows a cross-sectional view of the optical inspection apparatus 12 of this embodiment. This cross-sectional view is on the xz plane.

[0060] The basic configuration of the optical inspection apparatus 12 according to this embodiment is the same as that of the optical inspection apparatus 12 according to the first embodiment, including the various modifications. This embodiment further includes a beam splitter 28. The illumination unit 22 has a plurality (in this case, three) of light sources 32a, 32b, and 32c, an aperture 34, and a lens 36.

[0061] Furthermore, the optical inspection system 10 according to this embodiment further includes a transport device 16 for transporting an object S. The object S is transported in the transport direction indicated by the arrow in Figure 6. Here, the transport direction is referred to as the x-direction. The transport device 16 can be any type, such as a belt conveyor, roller conveyor, or linear stage. However, the transport speed of the transport device 16 can be controlled, for example, by the processing device 14. For simplicity, here we assume that the transport speed of the object S is constant. Typically, products in various manufacturing processes are transported in this manner.

[0062] The wavelength selection unit 26 comprises, in order along the x-direction, a first wavelength selection region 52, a second wavelength selection region 54, and a third wavelength selection region 56. Each wavelength selection region 52, 54, and 56 is uniform in the depth direction (y-direction) and has a stripe shape. Although multiple wavelength selection regions 52, 54, and 56 are arranged in this cross-section, each wavelength selection region 52, 54, and 56 does not change with respect to the depth direction perpendicular to this cross-section.

[0063] In this embodiment, the wavelength selection section 26 is anisotropic with respect to the optical axis of the imaging optical element 42. That is, the wavelength selection regions 52, 54, and 56 are not concentric circles that change only in the radial direction from the optical axis.

[0064] The three light sources 32a, 32b, and 32c are composed of, for example, LEDs that emit white light. The LEDs may be, for example, multiple 3.3mm x 3.3mm surface-emitting LEDs arranged in an array. The three light sources (surface-emitting light sources) 32a, 32b, and 32c are arranged uniformly in one direction, for example, at the focal plane of the cylindrical lens 36. The ON / OFF state of the light emission of the three light sources 32a, 32b, and 32c is controlled by the processing device 14. The three light sources 32a, 32b, and 32c are emitted simultaneously.

[0065] The illumination unit 22 simultaneously emits a first illumination beam L1, a second illumination beam L2, and a third illumination beam L3, which are then irradiated onto the surface of the object S along the optical axis of the imaging optical element 42 by the beam splitter 28. This type of illumination is called coaxial incident illumination.

[0066] The opening 34 is located near the exit of the lighting unit 22 from which the illumination light is emitted. The opening 34 is slit-shaped (stripe-shaped), for example, with the depth direction being the longitudinal direction and its dimension being 200 mm, and the slit width D in the transverse direction perpendicular to it (the z-direction in this embodiment) being 20 mm. The transverse view shown in Figure 6 shows the transverse direction.

[0067] Let's assume that the illumination lens 36 is, for example, a cylindrical lens with a longitudinal dimension of 200 mm and a focal length f of, for example, 20 mm. However, the illumination lens 36 is not limited to this; it could be a free-form lens, a Fresnel lens, or a concave mirror.

[0068] With the above configuration, the illumination light from the first light source 32a, the second light source 32b, and the third light source 32c in this cross-section is parallel light. However, the total divergence angle in this cross-section is the value obtained by dividing the LED light emission dimension of 3.3 mm by the focal length f of 20 mm. That is, the total divergence angle is approximately 10°. At this time, the divergence angle is half of that, or 5°. Illumination light with a divergence angle of this magnitude is considered to be essentially parallel light.

[0069] The operation of the optical inspection system 10 of this embodiment will be described below.

[0070] When the first light source 32a is turned on, the first illumination light L1 is generated. When the second light source 32b is turned on, the second illumination light L2 is generated. When the third light source 32c is turned on, the third illumination light L3 is generated. These illumination lights L1, L2, and L3 can be turned on at the same time. However, they can also be turned on sequentially in chronological order. By turning on the illumination lights L1, L2, and L3 in this order and taking an image with the image sensor 44 each time they are turned on, it becomes clear which illumination light L1, L2, and L3 acquired the image of which region. Here, we assume that the first light source 32a, the second light source 32b, and the third light source 32c are turned on at the same time.

[0071] The first illumination light L1, the second illumination light L2, and the third illumination light L3 are parallel light with a divergence angle of approximately 5°. The illumination angle θ is defined as the angle that each parallel light's principal ray makes with the optical axis of the imaging unit 24. In this cross-section, the illumination angle θ is considered positive when counterclockwise. The illumination angles θ are assumed to be -5° for the first illumination light L1, 0° for the second illumination light L2, and 5° for the third illumination light L3.

[0072] In the cross-section shown in Figure 6, the width of the illumination field of the first illumination light L1, the second illumination light L2, and the third illumination light L3 on the surface of object S can be adjusted by the slit width D of the opening 34 of the illumination unit 22. The width W of the illumination field will be at least wider than the slit width D. Here, the width W of the illumination field will be at least 20 mm.

[0073] Assume that the surface of object S transported by the transport device 16 is curved. The normal directions at the first object point O1, the second object point O2, and the third object point O3 are different. Furthermore, assume that the first object point O1 is a mirror surface, the second object point O2 has a minute defect, and the third object point O3 also has a minute defect.

[0074] When the first object point O1 is illuminated by the first illumination light L1, the spread of the directional distribution of light from the first object point O1 is narrow and can be represented by the first BRDF. Light with the directional distribution of the first BRDF passes only through the second wavelength selection region 54 of the wavelength selection unit 26 and is imaged at the first image point I1 by the imaging optical element 42 of the imaging unit 24.

[0075] When the second object point O2 is illuminated by the second illumination light L2, the spread of the directional distribution of light from the second object point O2 becomes relatively wide and can be represented by a second BRDF. Light with the directional distribution of the second BRDF passes through all of the first wavelength selection region 52, the second wavelength selection region 54, and the third wavelength selection region 56 of the wavelength selection unit 26 and is imaged onto the second image point I2 by the imaging optical element 42 of the imaging unit 24.

[0076] When the third object point O3 is illuminated by the third illumination light L3, the spread of the directional distribution of light from the third object point O3 becomes relatively wide and can be represented by a third BRDF. Light with the directional distribution of the third BRDF passes through all of the first wavelength selection region 52, the second wavelength selection region 54, and the third wavelength selection region 56 of the wavelength selection unit 26 and is imaged onto the third image point I3 by the imaging optical element 42 of the imaging unit 24.

[0077] The light at the image points I1, I2, and I3 formed in the imaging unit 24 is received by any pixel of the image sensor 44. This allows images of each object point O1, O2, and O3 to be acquired.

[0078] As described above, even if the surface of object S is curved, the number of wavelength-selective regions 52, 54, and 56 through which light passes changes depending on the BRDF of the surface of object S. In other words, there is an effect that the BRDF on a curved surface can be identified by the number of colors. If the BRDF can be identified, there is an effect that the surface properties and minute shapes of object S can be identified.

[0079] Furthermore, in Figure 6, the first object point O1, the second object point O2, and the third object point O3 are all captured as images by the image sensor 44 of the imaging unit 24. The reason why all object points O1, O2, and O3 can be captured in this way is that the first illumination light L1, the second illumination light L2, and the third illumination light L3 are oriented in different directions, and even if the surface of object S is curved, the light from each of the object points O1, O2, and O3 reaches the imaging unit 24. If the first illumination light L1, the second illumination light L2, and the third illumination light L3 were all oriented in the same direction, one of the object points would not be captured in the image. In other words, one of the object points would not reach the imaging unit 24, and the pixel at the corresponding image point would become dark.

[0080] The imaging unit 24 exposes the image sensor 44 using an electrical shutter controlled by the processing unit 14, and acquires an image. However, the exposure controlled by the shutter does not have to be electrical; it may be mechanical.

[0081] Figure 7 shows a cross-sectional view of an object S being transported in the transport direction at the moment (first time) when the image sensor 44 is exposed by the shutter. The optical inspection device 12 is not shown in Figure 7.

[0082] In the cross-sectional view shown in Figure 7, the widths of the illumination fields of the illumination lights L1, L2, and L3 along the x-direction may differ for the first illumination light L1, the second illumination light L2, and the third illumination light L3. The smallest of these illumination fields along the x-direction is defined as the representative illumination field width (illumination field width) W. Here, the representative illumination field width W is assumed to be 20 mm.

[0083] The timing of the shutter release in the imaging unit 24 is set to occur every time the transport distance along the transport direction advances by the representative illumination field width W. In other words, the shutter is released and an image is acquired every 20 mm of transport. That is, the imaging unit 24 captures an image while transporting the object S in a predetermined transport direction.

[0084] Figure 8 shows a schematic diagram of image I acquired by the imaging unit 24. In this image I, the first imaging region A1 is the image region exposed by the first illumination light L1, the second imaging region A2 is the image region exposed by the second illumination light L2, and the third imaging region A3 is the image region exposed by the third illumination light L3.

[0085] In the first imaging region A1, the normal direction of the first object point O1 is opposite to the direction of the first illumination light L1, so that the reflected light from the first illumination light L1 can reach the imaging unit 24. Therefore, the first object point O1 is captured in image I. On the other hand, if the relationship between the normal direction of the first object point O1 and the direction of the first illumination light L1 deviates significantly, the reflected light from the first illumination light L1 cannot reach the imaging unit 24, and the first object point O1 will not be captured in the image.

[0086] Here, the relationship between the normal direction and the illumination light being opposite means that the direction of the normal direction and the direction of the principal rays of the illumination light are substantially opposite to each other. However, they do not need to be exactly opposite; they only need to be opposite within the range of the illumination light's divergence angle.

[0087] Similarly, for the second object point O2 and the third object point O3, the normal direction at the object point is opposite to the direction of the second illumination light L2 and the third illumination light L3, so that reflected light from the illumination light can reach the imaging unit 24. Therefore, the second object point O2 and the third object point O3 will be captured in image I. On the other hand, if the normal direction at the second object point O2 and the third object point O3 deviates significantly from the opposite relationship between the directions of the second illumination light L2 and the third illumination light L3, reflected light from the second illumination light L2 and the third illumination light L3 cannot reach the imaging unit 24, and the second object point O2 and the third object point O3 will not be captured in image I.

[0088] Figure 9 shows the state after the object S has moved along the transport direction by the transport device 16 by a representative irradiation field width W (e.g., 20 mm) from the position of the object S in Figure 7.

[0089] Figure 9 shows a cross-sectional view of object S, and the optical inspection device 12 is not shown. Figure 10 shows the image I acquired by the imaging unit 24.

[0090] In the first imaging region A1, the normal direction of the first object point O1 deviates significantly from the direction of the first illumination light L1, so the reflected light from the first illumination light L1 cannot reach the imaging unit 24. Therefore, the first object point O1 is not captured in image I.

[0091] In the second imaging region A2, the normal direction of the second object point O2 is opposite to the direction of the second illumination light L2, so that the reflected light from the second illumination light L2 can reach the imaging unit 24. Therefore, the second object point O2 is captured in image I.

[0092] In the third imaging region A3, the normal direction of the third object point O3 deviates significantly from the direction opposite to that of the third illumination light L3. Therefore, the reflected light from the third illumination light L3 cannot reach the imaging unit 24. Consequently, the third object point O3 is not captured in image I.

[0093] As described above, the process of acquiring an image is repeated each time the object moves along the transport direction by a representative illumination field width W, thereby acquiring a series of multiple images. In this way, even if the surface of object S is curved, if the normal direction on the curved surface is opposite to the illumination light, that region will be captured as an image. In other words, each region of the surface of object S will be captured somewhere in the series of acquired images. On the other hand, if the surface of object S is flat, it will always be captured in the second imaging region. In this way, it is possible to capture curved surfaces and other surfaces of object S, whether they are flat or curved.

[0094] Furthermore, whether the surface of object S is flat or curved, the number of wavelength-selective regions through which light passes changes depending on the BRDF of the surface of object S. In other words, there is an effect that allows us to identify the BRDF on a curved surface by the number of colors. If the BRDF can be identified, there is an effect that allows us to identify the surface properties and minute shapes of object S.

[0095] Figure 11 shows an image including three object points and their vicinity, captured using an optical inspection system 10 having the optical inspection device 12 shown in Figure 6.

[0096] In the example shown in Figure 11, the normal direction (tilt angle: -2°±1.0; where ± represents the maximum amplitude, meaning it cannot swing any further) in the illumination field of the first illumination light L1 deviates significantly from the relationship where it is opposite to the direction of the first illumination light L1. Therefore, the reflected light from the first illumination light L1 cannot reach the imaging unit 24. Consequently, the illumination field of the first illumination light L1 is not visible in the bottom of image I in Figure 11.

[0097] The normal direction (tilt angle: 0°±1.0; where ± represents the maximum amplitude, meaning it cannot swing any further) in the field of the second illumination light L2 is opposite to the direction of the second illumination light L2. Therefore, reflected light from the second illumination light L2 can reach the imaging unit 24. As a result, the field of illumination light L2 is projected onto image I in the vertical center of image I in Figure 11.

[0098] The normal direction (tilt angle: 2°±1.0; where ± represents the maximum amplitude, meaning it cannot swing any further) in the field of illumination of the third illumination light L3 is opposite to the direction of the third illumination light L3. Therefore, the reflected light from the third illumination light L3 can reach the imaging unit 24. As a result, the field of illumination of the third illumination light L3 is captured in the uppermost part of image I in Figure 11.

[0099] In this way, while the object is being transported by the transport device 16, the number of colors can be obtained by performing a color number estimation process on the image I, and the directional distribution of scattered light from the surface of the object S can be identified based on the number of colors (S103). Since BRDF correlates with the properties and micro-shape of the surface S, this embodiment has the effect of being able to identify the differences in the properties and micro-shape of each object point O1, O2, and O3 on the surface of the object S. As a result, the properties and micro-shape of the surface S (the state of the surface S) can be identified non-contact without spectrally spectroscopy of the illumination (S104).

[0100] The optical inspection system 10 can obtain information about the surface properties of an object S by, for example, transporting the object S at a predetermined speed and in a predetermined transport direction using a transport device 16, and exposing the image sensor 44 with a shutter at predetermined time intervals.

[0101] As described above, this embodiment provides an optical inspection device 12, an optical inspection system 10, an optical inspection method, and an optical inspection program that can acquire information about the surface of an object S, including curved surfaces.

[0102] (modified version) Figures 12 to 15 show various examples of wavelength selection units 26.

[0103] The example of the wavelength selection section 26 shown in Figure 12 is one in which, for example, sets of red, green, and blue regions 26a, formed with equal widths, are repeated in the x-axis direction. In the wavelength selection section 26 shown in Figure 12, the first wavelength selection region 52, the second wavelength selection region 54, and the third wavelength selection region 56 are formed in a stripe shape with approximately the same width.

[0104] The example of the wavelength selection unit 26 shown in Figure 13 is an example that combines, for example, a first region (wavelength selection region) 26a of red, green, and blue sets, formed with equal widths of a first width, which is repeated in the x-axis direction, with a second region (wavelength selection region) 26b of red, green, and blue sets, which is formed with a width greater than the first width. The wavelength selection unit 26 shown in Figure 13 has a first region 26a and a second region 26b. The first region 26a and the second region 26b are arranged in the left-right direction (x-axis direction) in Figure 13. The first region 26a is formed in the same way as the wavelength selection unit 26 shown in Figure 12. In the second region 26b, each wavelength selection region is formed wider in the left-right direction than the width of the wavelength selection unit 26 shown in Figure 12 and the first region 26a in Figure 13.

[0105] The example of the wavelength selection unit 26 shown in Figure 14 is an example in which a pair of two color regions (wavelength selection regions) 26a, for example, red and blue, are repeated in the x-axis direction. Therefore, each region 26a of the wavelength selection unit 26 has a first wavelength selection region 52 and a second wavelength selection region 54. The pair of wavelength selection regions 52 and 54 in region 26a is repeated in the left-right direction in Figure 14. The widths of the respective wavelength selection regions 52 and 54 are, for example, constant.

[0106] The wavelength selection section 26 shown in Figure 15 has a first region 26a, a second region 26b, and a third region 26c. The first region 26a, the second region 26b, and the third region 26c are arranged in the left-to-right direction in Figure 15. In the first region 26a, each wavelength selection region 52, 54, and 56 is formed wider than in the second region 26b. In the second region 26b, each wavelength selection region 52, 54, and 56 is formed narrower than in the third region 26c. In the third region 26c, each wavelength selection region 52, 54, and 56 is formed wider than in the second region 26b.

[0107] Thus, the wavelength selection unit 26 shown in Figures 12 to 15 has at least two other wavelength selection regions having the same wavelength spectral characteristics as at least two wavelength selection regions. The wavelength selection unit 26 formed in this way can be used as the wavelength selection unit described in the first and second embodiments. Furthermore, the wavelength selection unit 26 formed in this way can be used as the wavelength selection unit described in the third embodiment.

[0108] (Third embodiment) The optical inspection system 10 according to the third embodiment will be described below with reference to Figure 16.

[0109] Figure 16 shows a cross-sectional view of the optical inspection apparatus 12, the processing apparatus 14, and the transport apparatus 16 of this embodiment.

[0110] The light source 32 of the illumination unit 22 shown in Figure 16 is an LED surface-emitting light source. The light source 32 may be positioned at the focal plane of the illumination lens 36 to create a fan beam. In other words, the illumination light emitted from the illumination unit 22 according to this embodiment may be a group of rays including the first illumination light L1 and the second illumination light L2 described in the first embodiment, which are parallel lights in two different directions. The illumination light formed by this entire group of rays may be illumination light that gradually spreads as it moves away from the light source 32. In the cross-sectional view shown in Figure 16, the dimensions of the light-emitting surface of the light source 32 are, for example, 10 mm. The illumination lens 36 is, for example, a Fresnel lens, with a longitudinal direction of 600 mm and a focal length f of, for example, 10 mm. In this case, the total angle of divergence of the illumination light as a whole group of rays is, for example, approximately 53°.

[0111] In this embodiment, the illumination light L can simultaneously irradiate the first object point O1, the second object point O2, and the third object point O3. Furthermore, a continuous illumination field can be formed on the surface of the object S by the illumination light L. Therefore, unlike the images I shown in Figures 8 and 10, there is an effect in that the entire pixel area of ​​the image sensor 44 of the imaging unit 24 can be effectively utilized.

[0112] Therefore, according to this embodiment, it is possible to provide an optical inspection device 12, an optical inspection system 10, an optical inspection method, and an optical inspection program that can acquire information about the surface of an object S, including curved surfaces.

[0113] According to at least one embodiment described above, it is possible to provide an optical inspection device 12, an optical inspection system 10, an optical inspection method, and an optical inspection program that can acquire information about the surface of an object S, including curved surfaces.

[0114] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. The claims of this application as they were at the time of filing are included below. [Note 1] A first illumination beam is shone onto a first point on the surface of an object, A second illumination light, directed in a direction different from the first illumination light, is shone onto a second object point on the surface of the object, which has a normal direction different from the normal direction of the first object point. Lighting section, A wavelength selection unit having at least two wavelength selection regions that selectively allow light of different wavelength spectra to pass through, When the normal direction at the first object point is opposite to the direction of the first illumination light, the light from the first object point can be imaged through the wavelength selection unit. When the normal direction at the second object point is opposite to the direction of the second illumination light, the light from the second object point can be imaged through the wavelength selection unit. Imaging unit, Equipped with, The wavelength selection unit is positioned between the imaging unit and the surface of the object. Optical inspection equipment. [Note 2] The optical inspection apparatus as described in Appendix 1, wherein the illumination unit irradiates the surface of the object with the first illumination light and the second illumination light, respectively, as parallel light. [Note 3] The imaging unit includes an imaging optical element having an optical axis, The wavelength selection section is anisotropic with respect to the optical axis. The optical inspection apparatus described in Appendix 1 or Appendix 2. [Note 4] The optical inspection apparatus according to Appendix 1 or Appendix 2, wherein the wavelength selection unit has at least two other wavelength selection regions having the same wavelength spectral characteristics as the at least two wavelength selection regions. [Note 5] The aforementioned lighting unit is A lens that is uniform in one direction, A surface-emitting light source provided at the focal plane of the aforementioned lens and An optical inspection apparatus as described in Appendix 1 or Appendix 2, having the following features. [Note 6] The optical inspection apparatus described in Appendix 1 or Appendix 2, A processing device connected to the optical inspection apparatus and Equipped with, The aforementioned processing apparatus is The number of colors received by the color channel of each pixel in the imaging unit is acquired. The surface condition of the object is inspected based on the aforementioned number of colors. Optical inspection system. [Note 7] The optical inspection apparatus described in Appendix 1 or Appendix 2, A conveying device for transporting the aforementioned object An optical inspection system equipped with the following features. [Note 8] The lighting unit has an opening near the outlet from which the illumination light is emitted. The transport device transports the object at intervals of illumination field width determined by the width of the aperture, while the imaging unit captures an image of the surface of the object. The optical inspection system described in Appendix 7. [Note 9] To irradiate a first point on the surface of an object with a first illumination light, Illuminating a second object point on the surface of the object, having a normal direction different from the normal direction of the first object point, with a second illumination light in a direction different from the first illumination light, When the normal direction at the first object point is opposite to the direction of the first illumination light, the light from the first object point is imaged through a wavelength selector having at least two wavelength selector regions that allow light of different wavelength spectra to pass through. When the normal direction at the second object point is opposite to the direction of the second illumination light, the light from the second object point is imaged through the wavelength selection unit at the same time as the light from the first object point is imaged. Optical inspection methods, including those mentioned above. [Note 10] The optical inspection method described in Appendix 9, wherein the imaging includes imaging while transporting the object in a predetermined transport direction. [Note 11] To illuminate a first point on the surface of an object with a first illumination beam, A second object point on the surface of the object, having a normal direction different from the normal direction of the first object point, is illuminated with a second illumination light in a direction different from the first illumination light. When the normal direction at the first object point is opposite to the direction of the first illumination light, the light from the first object point is imaged through a wavelength selector having at least two wavelength selector regions that allow light of different wavelength spectra to pass through. When the normal direction at the second object point is opposite to the direction of the second illumination light, the light from the second object point is imaged through the wavelength selection unit at the same time as the light from the first object point is imaged. An optical inspection program that causes the processor to execute. [Note 12] The optical inspection program described in Appendix 11 includes imaging the object while transporting it in a predetermined transport direction. [Explanation of symbols]

[0115] 10...Optical inspection system, 12...Optical inspection device, 14...Processing device, 16...Transport device, 22...Illumination unit, 24...Imaging unit, 26...Wavelength selection unit, 42...Imaging optical element, 44...Image sensor, 52...First wavelength selection region, 54...Second wavelength selection region, 61...Processor, I1...First image point, I2...Second image point, L1...First illumination light, L2...Second illumination light, O1...First object point, O2...Second object point.

Claims

1. A first illumination beam is shone onto a first point on the surface of an object, A second illumination light, directed in a direction different from the first illumination light, is shone onto a second object point on the surface of the object, which has a normal direction different from the normal direction of the first object point. Lighting section, A wavelength selection unit having at least two wavelength selection regions that selectively allow light of different wavelength spectra to pass through, The system comprises an imaging optical element and an image sensor positioned on the image plane of the imaging optical element, wherein the wavelength selection unit is positioned between the imaging optical element and the surface of the object. When the normal direction at the first object point is opposite to the direction of the first illumination light, the light from the first object point can be passed through the wavelength selection unit and the imaging optical element in order and captured by the image sensor. When the normal direction at the second object point is opposite to the direction of the second illumination light, the light from the second object point can be imaged by the image sensor by passing it sequentially through the wavelength selection unit and the imaging optical element. Imaging unit, Equipped with, Optical inspection equipment.

2. The illumination unit irradiates the surface of the object with the first illumination light and the second illumination light, each as parallel light. The optical inspection apparatus according to claim 1.

3. The imaging optical element of the imaging unit has an optical axis, The wavelength selection section is anisotropic with respect to the optical axis. The optical inspection apparatus according to claim 1 or claim 2.

4. The wavelength selection unit has at least two other wavelength selection regions having the same wavelength spectral characteristics as the at least two wavelength selection regions. The optical inspection apparatus according to claim 1 or claim 2.

5. The first illumination light and the second illumination light from the illumination unit are bundles of parallel light beams directed in multiple directions, and the light spreads out in a fan shape toward the surface of the object, irradiating the surface of the object with the light. The optical inspection apparatus according to claim 1.

6. The aforementioned lighting unit is A lens that is uniform in one direction, A surface-emitting light source provided at the focal plane of the aforementioned lens and An optical inspection apparatus according to claim 1 or claim 2, having the following features.

7. An optical inspection apparatus according to claim 1 or claim 2, A processing device connected to the optical inspection apparatus and Equipped with, The aforementioned processing apparatus is The number of colors received by the color channel of each pixel in the imaging unit is acquired. The surface condition of the object is inspected based on the aforementioned number of colors. Optical inspection system.

8. An optical inspection apparatus according to claim 1 or claim 2, A conveying device for transporting the aforementioned object An optical inspection system equipped with the following features.

9. The lighting unit has an opening near the outlet from which the illumination light is emitted. The transport device transports the object at intervals of illumination field width determined by the width of the aperture, while the imaging unit captures an image of the surface of the object. The optical inspection system according to claim 8.

10. Illuminating a first point on the surface of an object with a first illumination light, Illuminating a second object point on the surface of the object, having a normal direction different from the normal direction of the first object point, with a second illumination light in a direction different from the first illumination light, When the normal direction at the first object point is opposite to the direction of the first illumination light, the light from the first object point is passed sequentially through a wavelength selection unit having at least two wavelength selection regions that allow light of different wavelength spectra to pass through, and an imaging optical element, and then imaged by an image sensor positioned on the image plane of the imaging optical element. When the normal direction at the second object point is opposite to the direction of the second illumination light, the light from the second object point is imaged by the image sensor at the same time as the light from the first object point is imaged, passing through the wavelength selection unit and the imaging optical element in sequence. Optical inspection methods, including those mentioned above.

11. The irradiation of the first illumination light and the irradiation of the second illumination light include irradiating the surface of the object with light that spreads out in a fan shape toward the surface of the object as a plurality of parallel beams of light directed toward a plurality of directions. The optical inspection method according to claim 10.

12. The imaging described above includes imaging while transporting the object in a predetermined transport direction. The optical inspection method according to claim 10 or claim 11.

13. To illuminate a first point on the surface of an object with a first illumination light, A second object point on the surface of the object, having a normal direction different from the normal direction of the first object point, is illuminated with a second illumination light in a direction different from the first illumination light. When the normal direction at the first object point is opposite to the direction of the first illumination light, the light from the first object point is passed sequentially through a wavelength selection unit having at least two wavelength selection regions that allow light of different wavelength spectra to pass through, and an imaging optical element, and then captured by an image sensor positioned on the image plane of the imaging optical element. When the normal direction at the second object point is opposite to the direction of the second illumination light, the light from the second object point is imaged by the image sensor at the same time as the light from the first object point is imaged, passing through the wavelength selection unit and the imaging optical element in sequence. An optical inspection program that causes the processor to execute.

14. The act of irradiating the object with the first illumination light and the act of irradiating the object with the second illumination light includes irradiating the object's surface with light that spreads out in a fan shape toward the object's surface as a plurality of parallel beams of light moving toward the object's surface, The optical inspection program according to claim 13.

15. The act of imaging includes imaging while transporting the object in a predetermined transport direction. The optical inspection program according to claim 13 or claim 14.

Images