Optical inspection apparatus and optical inspection method

Abstract

To provide an optical inspection apparatus that can achieve high accuracy in an optical inspection of a surface of a subject.SOLUTION: An optical inspection apparatus comprises an imaging portion, a first wavelength selection portion, an illumination portion, and a second wavelength selection portion. The imaging portion includes an image sensor that can capture a subject by light from the subject. The first wavelength selection portion is provided on an optical axis of the imaging portion and selectively passes light of a plurality of predetermined wavelengths. The illumination portion illuminates the subject. The second wavelength selection portion is provided on an optical axis of the illumination portion and passes the light of the plurality of predetermined wavelengths complementarily to the first wavelength selection portion.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to an optical inspection apparatus and Optical inspection by law methods.

Background Art

[0002] In various industries, non-contact surface measurement of objects has become important. In the conventional method, there is a technique for obtaining BRDF information that can describe the surface state of an object surface by associating light rays with colors for each direction.

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 to be solved by the present invention is an optical inspection apparatus capable of improving the accuracy of optical inspection of the surface of an object to be inspected and Optical inspection lawis to provide.

Means for Solving the Problem

[0006] According to an embodiment, an optical inspection apparatus includes an imaging unit, a first wavelength selection unit, an illumination unit, and a second wavelength selection unit. The imaging unit includes an image sensor capable of imaging an object with light from the object. The first wavelength selection unit is provided on the optical axis of the imaging unit and passes light of a plurality of predetermined wavelengths a wavelength selected from of light through through. The illumination unit illuminates the object. The second wavelength selection unit is provided on the optical axis of the illumination unit and passes light of a plurality of predetermined wavelengths a wavelength selected from through. The first wavelength selection unit includes a first-1 region that shields light of the first wavelength and allows light of a second wavelength different from the first wavelength to pass through toward the image sensor, and a first-2 region that allows light of the first wavelength to pass through toward the image sensor and shields light of the second wavelength. The second wavelength selection unit includes a second-1 region that is similar in shape to the first-1 region, allows light of the first wavelength to pass through toward the object to be inspected, and shields light of the second wavelength, and a second-2 region that is similar in shape to the first-2 region, allows light of the second wavelength to pass through toward the object to be inspected, and shields light of the first wavelength. Among the pixels of the image sensor, at the first position where light from the object to be inspected is received, both light of the first wavelength and light of the second wavelength are received simultaneously. Among the pixels of the image sensor, at the second position where light from the object to be inspected is not received, neither light of the first wavelength nor light of the second wavelength is received. It is possible to create a contrast with light of at least two different wavelengths from the object to be inspected between the first position and the second position in the pixels of the image sensor.

Brief Description of the Drawings

[0007] [FIG. 1] Schematic cross-sectional view showing the operating principle of the optical inspection apparatus according to the first embodiment. [FIG. 2] Schematic view showing the first wavelength selection unit of the optical inspection apparatus shown in FIG. 1. [FIG. 3] Schematic view showing the second wavelength selection unit of the optical inspection apparatus shown in FIG. 1. [FIG. 4] Schematic cross-sectional view showing the operating principle of the optical inspection apparatus according to the first embodiment. [FIG. 5] Schematic flowchart showing the processing flow of the processing device of the optical inspection apparatus shown in FIGS. 1 and 4. [FIG. 6] Schematic view showing a modification example of the first wavelength selection unit (and the second wavelength selection unit) used in the optical inspection apparatus according to the first embodiment. [FIG. 7] Schematic cross-sectional view showing the operating principle when performing optical inspection using the first wavelength selection unit (and the second wavelength selection unit) shown in FIG. 6. [FIG. 8] Schematic view showing an example of the first wavelength selection unit (and the second wavelength selection unit) used in the optical inspection apparatus according to the first embodiment. [FIG. 9] Schematic view showing an example of the first wavelength selection unit (and the second wavelength selection unit) used in the optical inspection apparatus according to the first embodiment. [FIG. 10] Schematic diagram showing an example of the first wavelength selection unit (and the second wavelength selection unit) used in the optical inspection apparatus according to the first embodiment. [FIG. 11] Schematic diagram showing an example of the first wavelength selection unit (and the second wavelength selection unit) used in the optical inspection apparatus according to the first embodiment. [FIG. 12] Schematic diagram showing an example of the first wavelength selection unit (and the second wavelength selection unit) used in the optical inspection apparatus according to the first embodiment. [FIG. 13] Schematic cross-sectional view showing the operating principle of the optical inspection apparatus according to the second embodiment. [FIG. 14] Schematic cross-sectional view showing the operating principle of the optical inspection apparatus according to the third embodiment. [FIG. 15] Schematic diagram showing the second wavelength selection unit of the optical inspection apparatus shown in FIG. 14. [FIG. 16] Schematic cross-sectional view showing the operating principle of the optical inspection apparatus according to the fourth embodiment. [FIG. 17] Schematic cross-sectional view showing the operating principle of the optical inspection apparatus according to the fifth 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 thicknesses and widths of the respective parts, the ratios of the sizes between the 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 reference numerals are given to the same elements as those described above with respect to the previously presented figures, and detailed descriptions are omitted as appropriate.

[0009] In this specification, light is a type of electromagnetic wave, and it is assumed to include X-rays, ultraviolet rays, visible light, infrared rays, microwaves, etc. In the present embodiment, it is assumed that the light is visible light, and for example, the wavelength is in the range of 450 nm to 700 nm.

[0010] (First Embodiment) The optical inspection apparatus 10 according to this embodiment will be described in detail with reference to FIGS. 1 to 5.

[0011] FIG. 1 shows a schematic cross-sectional view of the optical inspection apparatus 10 of this embodiment.

[0012] The optical inspection apparatus 10 according to this embodiment includes an imaging unit 12 and an illumination unit 14.

[0013] The imaging unit 12 includes an imaging optical element (first imaging optical element) 22 and an image sensor (also referred to as a sensor) 26 that receives light from the object S. The imaging unit 12 is provided with a first wavelength selection unit 24 that selectively passes light of a plurality of predetermined wavelengths. The illumination unit 14 includes a light source 32 and an illumination lens (second imaging optical element) 36. The illumination unit 14 is provided with a second wavelength selection unit 34 that selectively passes light of a plurality of predetermined wavelengths.

[0014] The imaging optical element 22 is, for example, an imaging lens. In FIG. 1, the imaging lens is schematically depicted as a single lens, but it may be a combination lens composed of a plurality of lenses. Alternatively, the imaging optical element 22 may be a concave mirror, a convex mirror, or a combination thereof. That is, the imaging optical element 22 may be any optical element that has the function of collecting a group of light rays emitted from a single point of an object, that is, an object point, at a conjugate image point. The imaging of a group of light rays emitted from an object point on the object surface being collected (condensed) at an image point by the imaging optical element is called imaging. Alternatively, it is also said that the object point is moved to the image point (the conjugate point of the object point). Also, the set surface of the conjugate points to which a group of light rays emitted from a sufficiently distant object point is moved by the imaging optical element is called the focal plane of the imaging optical element. Also, a line perpendicular to the focal plane and passing through the center of the imaging element is defined as the optical axis L1 of the imaging unit 12. At this time, the conjugate image point of the object point moved by this light ray is called the focal point.

[0015] The first wavelength selection unit 24 is disposed on the optical axis L1. The first wavelength selection unit 24 is disposed on the first focal plane F1 of the imaging optical element 22 or in the vicinity thereof. By disposing the first wavelength selection unit 24 on the focal plane F1 of the imaging optical element 22 in this manner, color coding according to the direction of the light beam becomes possible (see Non-Patent Document 1).

[0016] The first wavelength selection unit 24 has at least two or more wavelength selection regions 24a and 24b. Let two of those wavelength selection regions be the first-first wavelength selection region 24a and the first-second wavelength selection region 24b. The first-second wavelength selection region 24b allows light rays having the first wavelength to pass through. Here, allowing light rays to pass through means directing the light rays from the object point toward the image point by transmission or reflection. In the present embodiment, it is assumed that the first-second wavelength selection region 24b transmits light rays of the first wavelength. On the other hand, the first-second wavelength selection region 24b substantially blocks light rays of the second wavelength. Here, blocking means not allowing the light rays to pass through. That is, it means not directing the light rays from the object point toward the image point. However, blocking includes cases where the intensity of the light rays is significantly reduced and the remaining small components are allowed to pass through. The first-first wavelength selection region 24a allows light rays having the second wavelength to pass through. In the present embodiment, it is assumed that the first-first wavelength selection region 24a transmits light rays of the second wavelength. On the other hand, the first-first wavelength selection region 24a substantially blocks light rays of the first wavelength. For example, let the first wavelength be red light of 650 nm and the second wavelength be blue light of 450 nm. However, it is not limited thereto, and each wavelength may be anything.

[0017] An image sensor (hereinafter also abbreviated as a sensor) 26 can image a test object S with light from the test object S. The image sensor 26 has at least one or more pixels, and each pixel is assumed to be able to receive light rays of at least two different wavelengths, that is, a light ray of a first wavelength and a light ray of a second wavelength. However, it is not necessary to be able to distinguish between those two different wavelengths. That is, the sensor 26 may be a monochrome sensor. A surface including the region where the sensor 26 is disposed is defined as the image plane of the imaging optical element. The sensor 26 may be an area sensor or a line sensor. An area sensor is one in which pixels are arranged in an area within the same plane. A line sensor is one in which pixels are arranged in a line. Also, each pixel may be provided with color channels of three channels of R, G, and B. However, a one-channel monochrome sensor may also be used. In the present embodiment, the sensor 26 is assumed to be an area sensor, and is an area sensor capable of receiving two lights, red and blue, at each pixel. That is, it is assumed that blue light with a wavelength of 450 nm and red light with a wavelength of 650 nm can be received at each pixel.

[0018] The light source 32 uses, for example, a surface-emitting LED. However, it is not limited to this, and the light source 32 may be anything as long as it emits light. The light source 32 may be, for example, a surface-emitting OLED, a combination of a xenon lamp or a halogen lamp and a diffuser plate, an X-ray source, or an infrared source.

[0019] The second wavelength selection unit 34 is disposed on the optical axis L2. The second wavelength selection unit 34 has at least two or more wavelength selection regions 34a and 34b. Among them, two of the wavelength selection regions are defined as the second-1 wavelength selection region 34a and the second-2 wavelength selection region 34b. The second-1 wavelength selection region 34a allows light rays having 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 second-1 wavelength selection region 34a substantially shields light rays having the second wavelength. Here, shielding means not allowing the light rays to pass through. That is, it means not directing the light rays from the object point to the image point. The second-2 wavelength selection region 34b allows a wavelength spectrum including light rays having the second wavelength to pass through. On the other hand, the second-2 wavelength selection region 34b substantially shields light rays having the first wavelength.

[0020] The illumination lens 36 is, for example, an imaging lens. In FIG. 1, the illumination lens 36 is schematically depicted as a single lens, but it may be a combination lens composed of a plurality of lenses. Alternatively, the illumination lens 36 may be a concave mirror, a convex mirror, or a combination thereof. That is, the illumination lens 36 may be any optical element having the function of collecting a group of light rays emitted from a point on the object, that is, an object point, to a conjugate image point. The imaging of a group of light rays emitted from an object point on the object surface being collected (condensed) to an image point by the illumination lens 36 is called imaging. Alternatively, it is also said that the object point is moved to the image point (the conjugate point of the object point). Also, the set surface of the conjugate points to which a group of light rays emitted from a sufficiently distant object point is moved by the illumination lens 36 is called the focal plane of the illumination lens (imaging optical element) 36. Also, the line perpendicular to the focal plane and passing through the center of the illumination lens 36 is defined as the optical axis L2 of the illumination unit 14. At this time, the conjugate image point of the object point moved by this light ray is called the focal point. Then, the second wavelength selection unit 34 is disposed at the second focal plane F2 of the illumination lens 36 or in the vicinity thereof.

[0021] In this way, by disposing the second wavelength selection unit 34 on the focal plane F2 of the illumination lens 36, it becomes possible to color (extract) light according to the direction of the light beam (see Non-Patent Document 1). That is, when the light from the light source 32 passes through the second wavelength selection unit 34, the wavelength spectrum of the light changes according to the direction of the light beam.

[0022] In the present embodiment, the light from the light emitting point E of the light source 32 passes through the second wavelength selection unit 34, propagates along the optical axis L2 of the illumination lens 36, and is imaged on the object point O on the surface of the object S via the beam splitter 38. Here, it can be considered that the optical axis L2 of the illumination unit 14 bends via the beam splitter 38.

[0023] The directional distribution of the reflected light from the object point O on the surface of the object S can be represented by a distribution function called BRDF (Bidirectional Reflectance Distribution Function). BRDF generally varies depending on the surface properties and shape. That is, it varies depending on the surface state of the object surface. For example, when the surface is rough, the reflected light spreads in various directions, so BRDF has a wide distribution. That is, the reflected light exists over a wide angle. On the other hand, when the surface becomes a mirror surface, the reflected light becomes almost only the specular reflection component, and BRDF has a narrow distribution. In this way, BRDF reflects the surface properties and shape of the object surface. Here, the surface properties and shape may be the surface roughness, micron-sized minute unevenness, the inclination of the surface, strain, etc. That is, anything related to the height distribution of the surface is acceptable. When the surface properties and shape are composed of a fine structure, the typical structure scale may be the nanoscale, the micron scale, the millimeter scale, or any scale.

[0024] The first wavelength selection unit 24 shown in FIG. 2 and the second wavelength selection unit 34 shown in FIG. 3 have complementarity. That is, they have at least a correlation relationship. Here, when the first wavelength selection unit 24 and the second wavelength selection unit 34 have complementarity, they have the following two characteristics.

[0025] As a first feature, the first wavelength selection unit 24 and the second wavelength selection unit 34 are similar in shape. Here, it is not necessary for the entire regions of the first wavelength selection unit 24 and the second wavelength selection unit 34 to be similar to each other. For example, the overall size and outer edge shape of the first wavelength selection unit 24 and the second wavelength selection unit 34 may be of any shape. That is, among the first wavelength selection unit 24 and the second wavelength selection unit 34, it is sufficient that the regions through which the light rays used for imaging pass are similar to each other.

[0026] Here, the cross-sectional view of the first wavelength selection unit 24 in FIG. 1 corresponds to the upper figure in FIG. 2. Also, the cross-section of the wavelength selection unit 24 in a plane orthogonal to the optical axis L1 corresponds to the lower figure in FIG. 2. The cross-sectional view of the second wavelength selection unit 34 in FIG. 1 corresponds to the right figure in FIG. 3. Also, the cross-sectional view of the wavelength selection unit 34 in a plane orthogonal to the optical axis L2 corresponds to the left figure in FIG. 3. And the cross-sectional view of the first wavelength selection unit 24 in a plane orthogonal to the optical axis L1 and the cross-sectional view of the wavelength selection unit 34 in a plane orthogonal to the optical axis L2 are similar in shape. That is, the first-1 wavelength selection region 24a of the first wavelength selection unit 24 and the second-1 wavelength selection region 34a of the second wavelength selection unit 34 are similar in shape. Similarly, the first-2 wavelength selection region 24b of the first wavelength selection unit 24 and the second-2 wavelength selection region 34b of the second wavelength selection unit 34 are similar in shape. However, the first wavelength selection unit 24 and the second wavelength selection unit 34 may have locally different shapes even in the region through which the light rays used for imaging pass or in its vicinity. This will be described in the following embodiment (see FIG. 14). For example, the second wavelength selection unit 34 may have a wavelength shielding portion 35. Also, the first wavelength selection unit 24 may have a similar shielding portion together with the wavelength shielding portion 35 or instead of the wavelength shielding portion 35.

[0027] The second feature is that the wavelength selection regions 24a and 24b of the first wavelength selection unit 24 and the wavelength selection regions 34a and 34b of the second wavelength selection unit 34 have a complementary relationship in their respective passing wavelength regions. That is, at least with respect to the passing wavelength regions, they have a correlation with each other. The wavelength regions of the light passing through the first-1 wavelength selection region 24a and the second-1 wavelength selection region 34a are different from each other, and the wavelength regions of the light passing through the first-2 wavelength selection region 24b and the second-2 wavelength selection region 34b are also different from each other. On the other hand, the first-1 wavelength selection region 24a and the second-2 wavelength selection region 34b have a common passing wavelength region with each other as the wavelength region for passing light, and the first-2 wavelength selection region 24b and the second-1 wavelength selection region 34a also have a common passing wavelength region with each other as the wavelength region for passing light.

[0028] That is, the light rays of the wavelength passing through the second-1 wavelength selection region 34a are shielded by the first-1 wavelength selection region 24a. The light rays of the wavelength passing through the second-1 wavelength selection region 34a pass through the first-2 wavelength selection region 24b. The light rays of the wavelength passing through the second-2 wavelength selection region 34b are shielded by the first-2 wavelength selection region 24b. The light rays of the wavelength passing through the second-2 wavelength selection region 34b pass through the first-1 wavelength selection region 24a.

[0029] It is assumed that the first wavelength selection unit 24 and the second wavelength selection unit 34 are similar in shape, and the similarity ratio is determined by the ratio of the focal length of the imaging optical element 22 to the focal length of the illumination lens 36. For example, if the focal length of the imaging optical element 22 is 100 mm and the focal length of the illumination lens 36 is 50 mm, the similarity ratio is 2 times. That is, the first wavelength selection unit 24 is a similar enlargement of the second wavelength selection unit 34 by 2 times.

[0030] As described above, it is assumed that the first wavelength selection unit 24 and the second wavelength selection unit 34 have complementarity in that they have a similar relationship in which they are similar in shape with a predetermined cross section, and they have a relationship with respect to the passing / shielding of a plurality of predetermined wavelengths in each region of both.

[0031] The processing device 16 is composed of, for example, a computer or the like, and includes a processor (processing circuit) and a storage medium. The processor includes any one of a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), a microcomputer, an FPGA (Field Programmable Gate Array), a DSP (Digital Signal Processor), and the like. The storage medium may include an auxiliary storage device in addition to a main storage device such as a memory. Examples of the storage medium include an HDD (Hard Disk Drive), an SSD (Solid State Drive), a magnetic disk, an optical disk (CD-ROM, CD-R, DVD, etc.), a magneto-optical disk (MO, etc.), and a non-volatile memory such as a semiconductor memory that can be written to and read from at any time.

[0032] In the processing device 16, only one or a plurality of each of the processor and the storage medium may be provided. In the processing device 16, the processor performs processing by executing a program or the like stored in a storage medium or the like. Further, the program executed by the processor of the processing device 16 may be stored in a computer (server) connected to the processing device 16 via a network such as the Internet, or a server in a cloud environment. In this case, the processor downloads the program via the network. In the processing device 16, image acquisition from the image sensor 26 and various calculation processes based on the image acquired from the image sensor 26 are executed by a processor or the like, and the storage medium functions as a data storage unit.

[0033] Further, at least a part of the processing by the processing device 16 may be executed by a cloud server configured in a cloud environment. The infrastructure of the cloud environment is composed of a virtual processor such as a virtual CPU and cloud memory. In one example, image acquisition from the image sensor 26 and various calculation processes based on the image acquired from the image sensor 26 are executed by the virtual processor, and the cloud memory functions as a data storage unit.

[0034] In addition, in this embodiment, the processing device 16 controls the image sensor 26. Further, the processing device 16 controls the light source 32.

[0035] Based on the above configuration, the operating principle of the optical inspection device 10 of this embodiment will be described with reference to FIGS. 1, 4, and 5.

[0036] The processing device 16 causes the light source 32 of the illumination unit 14 to emit light, and the image sensor 26 captures an image (step S101).

[0037] The light from the light-emitting point E of the light source 32 passes through the second wavelength selection unit 34, propagates along the optical axis L2 of the illumination lens 36, and is imaged on the object point O on the surface of the object S via the beam splitter 38. Here, for example, the first light ray B1 passes through the second-1 wavelength selection region 34a of the second wavelength selection unit 34 from the light-emitting point E of the light source 32, becomes red light including the first wavelength, passes through the illumination lens 36, is reflected by the beam splitter 38, and reaches the object point O of the object S. Also, the second light ray B2 passes through the second-2 wavelength selection region 34b of the second wavelength selection unit 34 from the light-emitting point E of the light source 32, becomes blue light including the second wavelength, passes through the illumination lens 36, is reflected by the beam splitter 38, and reaches the object point O of the object S.

[0038] Note that the second-1 wavelength selection region 34a of the second wavelength selection unit 34 shields light of a second wavelength different from the first wavelength. For this reason, the blue light, which is the second wavelength, is shielded by the second-1 wavelength selection region 34a of the second wavelength selection unit 34. The second-2 wavelength selection region 34b of the second wavelength selection unit 34 shields light of a first wavelength different from the second wavelength. For this reason, the red light, which is the first wavelength, is shielded by the second-2 wavelength selection region 34b of the second wavelength selection unit 34.

[0039] In FIG. 1, assume that the standard surface of the object S to be inspected is, for example, approximately a mirror surface. Also, this is called the standard surface. At this time, the light rays incident on the object point O of the object S are almost specularly reflected. That is, the BRDF at the object point O has a narrow directional distribution with the specular reflection component as the main component. On the other hand, as shown in FIG. 4, if there is a micron-sized uneven defect C at the object point O, the BRDF of the object point O has a wide distribution. However, the micron-sized uneven part may be regarded as the standard surface and the mirror surface as the defect. That is, it is arbitrary which surface is defined as the standard surface.

[0040] As shown in FIG. 1, among the light reflected at the object point O on the surface of the object S to be inspected, the specular reflection component is reflected in the specular reflection direction and travels toward the imaging optical element (imaging lens) 22. For example, when the first light ray B1 is reflected at the object point O, the directional distribution of the reflected light of the first light ray B1 can be represented by the first BRDF indicated by reference numeral 1. Among the reflected light represented by the first BRDF1, the specular reflection component passes through the beam splitter 38, passes through the imaging optical element 22, and is blocked by the first-1 wavelength selection region 24a of the first wavelength selection unit 24. At this time, if the first wavelength selection unit 24 does not exist, among the reflected light represented by the first BRDF1, the specular reflection component reaches the image point I on the image sensor 26.

[0041] Also, when the second light ray B2 is reflected at the object point O, the directional distribution of the reflected light of the second light ray B2 can be represented by the second BRDF indicated by reference numeral 2. Among the reflected light represented by the second BRDF2, the specular reflection component passes through the beam splitter 38, passes through the imaging optical element (imaging lens) 22, and is blocked by the first-2 wavelength selection region 24b of the first wavelength selection unit 24. At this time, if the first wavelength selection unit 24 does not exist, among the reflected light represented by the second BRDF2, the specular reflection component reaches the image point I on the image sensor 26.

[0042] Thus, since the first wavelength selection unit 24 and the second wavelength selection unit 34 have complementarity, among the light (the first light beam B1 and the second light beam B2) reflected by the object point O on the surface of the object S to be inspected, the specular reflection components are all blocked without reaching the image sensor 26. That is, as the image acquired by the image sensor 26, the whole is a black image, and the pixel values of the whole are substantially 0. This means that the light emitted by the light source 32 is not received by the image sensor 26.

[0043] Since the surface of the object S to be inspected is substantially a mirror surface and the light beam incident on the object point O is substantially specularly reflected, substantially the first BRDF1 and the second BRDF2 have mainly specular reflection components, and the reflected light is substantially blocked by the first wavelength selection unit 24. That is, as the image acquired by the image sensor 26, the whole is a black image, and the pixel values of the whole are substantially 0.

[0044] On the other hand, as shown in FIG. 4, when there is an unevenness C at the object point O of the object S to be inspected, the BRDF at the object point O has a wider distribution compared to that of a mirror-like surface which is a standard surface. That is, the first light beam B1 is reflected at the object point O and becomes the reflected light represented by the third BRDF indicated by, for example, reference numeral 3, and the second light beam B2 is reflected at the object point O and becomes the reflected light represented by the fourth BRDF indicated by, for example, reference numeral 4. In this case, the first light beam B1 is reflected at the object point O, passes through the beam splitter 38 and the imaging optical element 22, and a component that reaches the first-2 wavelength selection region 24b in addition to the first-1 wavelength selection region 24a of the first wavelength selection unit 24 is generated. The first-2 wavelength selection region 24b allows the first light beam B1 to pass through. Then, the first light beam B1 (the component thereof) that has passed through the first wavelength selection unit 24 reaches the image point I on the image sensor 26. Thereby, the first wavelength is received at the image point I. That is, the sensor 26 receives red light.

[0045] Similarly, the second light beam B2 is reflected at the object point O, passes through the beam splitter 38 and the imaging optical element 22, and a component that reaches the first wavelength selection region 24a in addition to the first-second wavelength selection region 24b of the first wavelength selection unit 24 is generated. The first wavelength selection region 24a allows the second light beam B2 to pass through. Then, the second light beam B2 (or its component) that has passed through the first wavelength selection unit 24 reaches the image point I on the image sensor 26. As a result, the second wavelength is received at the image point I. That is, the sensor 26 receives blue light.

[0046] As described above, like the test object S shown in FIG. 4, the sensor 26 simultaneously receives the first wavelength and the second wavelength for the object point O where the unevenness C exists. On the other hand, at the image point I for the object point O on the standard surface without the unevenness C like the test object S shown in FIG. 1, the sensor 26 does not receive any light.

[0047] The processing device 16 determines whether light from the surface of the test object S is received in the image acquired by the image sensor 26 (step S102).

[0048] If the processing device 16 receives light from the surface of the test object S with the image sensor 26 (step S102 - Yes), it determines that the unevenness C exists on the surface of the test object S (step S103). If the processing device 16 does not receive light from the surface of the test object S with the image sensor 26 (step S102 - No), it determines that the unevenness C does not exist on the surface of the test object S (step S104).

[0049] That is, the processing device (processor) 16 detects the presence or absence of reception of reflected light from the object S at each pixel of the image sensor 26. When the processing device (processor) 16 detects no reception of light at each pixel of the image sensor 26, it outputs that the surface of the object S corresponding to each pixel's image point I is a standard surface. When it detects reception of light, it outputs that the surface of the object S corresponding to the image point I is different from the standard surface. Therefore, the processing device 16 outputs the difference between the surface at the object point O corresponding to the pixel and the standard surface based on the detection result of the presence or absence of reception of light at each pixel of the image sensor 26. That is, when the detection result is no reception of light at each pixel of the image sensor 26, the processing device 16 outputs that the object point O of the object S corresponding to the pixel is on the standard surface. When the detection result is reception of light, it outputs that the object point O of the surface of the object S corresponding to the pixel is on a surface different from the standard surface.

[0050] Thereby, the processing device 16 can identify the presence or absence of unevenness C on the object S from the image acquired by the image sensor 26. Also, when there is unevenness C on the object S, the sensor 26 can receive light of not only the first wavelength but also the second wavelength simultaneously. Therefore, the S / N of the light received by the sensor 26 can be increased. On the other hand, if the sensor 26 receives only the first wavelength (red light) or only the second wavelength (blue light), the amount of light is less than when it receives both the first and second wavelengths, so the S / N is lower than when it receives both. That is, the processing device 16 obtains, for each pixel of the image captured by the image sensor 26, a position where no light is received as a dark black and a position where light is received as a bright color in which red light and blue light are mixed. Therefore, the processing device 16 can clearly show the contrast between the position where the unevenness C exists and the position where the unevenness C does not exist. That is, not only light and dark but also different colors can be used to clearly show the contrast between the two.

[0051] This embodiment has described an example of using two different wavelengths, i.e., the first wavelength and the second wavelength. However, it should be noted that the image sensor 26 can function without distinguishing between these two wavelengths. That is, generally, the object point O of the object S where the pixel value of the image point I is 0 has no unevenness C, and the processing device 16 can determine that there is unevenness C at positions where the pixel value is greater than 0. Therefore, the sensor 26 can use a monochrome sensor. Also, since the sensor 26 may use a color sensor, the range of options for the image sensor that can be used can be expanded.

[0052] Also, in this embodiment, the standard surface is a mirror surface, but the standard surface may be an uneven surface. In that case as well, since the BRDF of the standard surface and the BRDF on a different surface are different from each other, by appropriately adjusting the two complementary wavelength selection units, the same function can be achieved. For this reason, the processing device 16 outputs, for each pixel of the image sensor 26, the difference between the surface at the object point O corresponding to the pixel and the standard surface based on the detection result of the presence or absence of light reception. That is, the processing device 16 outputs that the object point O of the object S corresponding to the pixel is on a surface different from the standard surface when the detection result is no light reception for each pixel of the image sensor 26, and outputs that the object point O of the surface of the object S corresponding to the pixel is on the standard surface when the detection result is light reception. In this way, the presence or absence of light reception at each pixel of the image sensor 26 and the correctness of the standard surface can be set as appropriate.

[0053] In this embodiment, the imaging optical element 22 and the illumination lens 36 can be made common. That is, one imaging optical element 22 may be used as the illumination lens 36. In that case, the position of the beam splitter 38 is arranged on the side closer to the image sensor 26 than the imaging optical element 22. In this case, since the imaging optical element 22 and the illumination lens 36 are common (single), their respective focal lengths are equal.

[0054] In this embodiment, the ratio between the total area of the light-receiving surface of the image sensor 26 and the total area of the light-emitting surface of the light source 32 can be adjusted according to the focal length of the imaging optical element 22 or the illumination lens 36. That is, for example, for a light source 32 having an arbitrary light-emitting surface, the area of the image sensor 26 can be adjusted by adjusting the position of the imaging optical element 22 or the illumination lens 36.

[0055] Also, the beam splitter 38 may be a polarization beam splitter 38. In this case, only the light whose polarization direction has been rotated by scattering from the surface of the object S is received by the image sensor 26. As a result, there is an effect that the sensitivity to scattering can be increased.

[0056] The first wavelength selection unit 24 according to this embodiment is provided on the optical axis L1 of the imaging unit 12 between the optical paths of the object S and the imaging unit 12, and selectively passes light of a plurality of predetermined wavelengths. The second wavelength selection unit 34 is provided on the optical axis L2 of the illumination unit 14 (light source 32) between the optical paths of the illumination unit 14 and the object S, and selectively passes light of a plurality of predetermined wavelengths in a state complementary to the first wavelength selection unit 24. Therefore, when the optical inspection device 10 receives light from the surface of the object S by the image sensor 26 of the imaging unit 12, it is detected that the unevenness C exists on the surface of the object S, and when the optical inspection device 10 does not receive light from the surface of the object S by the image sensor 26 of the imaging unit 12, it is detected that the unevenness C exists on the surface of the object S. Then, the surface state of the object S can be determined based on the presence or absence of light reception, and the optical inspection of the surface of the object S can be made highly accurate. Therefore, according to this embodiment, it is possible to provide an optical inspection device 10, a processing device 16, an optical inspection method, and an optical inspection program capable of highly accurately performing an optical inspection of the surface of the object S.

[0057] (Modification example) When a color sensor is used as the image sensor 26 instead of a monochrome sensor, the image sensor 26 can distinguish between blue light and red light at each pixel. In that case, for example, when there is an uneven portion C at the object point O and the image sensor 26 receives only blue light, which is the second light beam, it means that the BRDF of the red light, which is the first light beam, is different from the BRDF of the blue light, which is the second light beam. In this case, it means that the distribution of the BRDF of the blue light, which is the second light beam, is wider than the BRDF of the red light, which is the first light beam. That is, the incident angle dependence of the BRDF can be grasped. As a result, more detailed BRDF information can be obtained, and thus there is an effect that more accurate optical inspection becomes possible.

[0058] As the first wavelength selection unit 24 and the second wavelength selection unit 34, various ones can be used. For example, the first wavelength selection unit 24 and the second wavelength selection unit 34 can identify the direction of the inclination of the surface of the object S to be inspected by imparting anisotropy around the optical axes L1, L2 of the optical inspection device 10. In that case, the image sensor 26 is a color sensor that can distinguish at least two different colors. Here, it is assumed that the image sensor 26 can distinguish the first wavelength (red) and the second wavelength (blue). For example, as shown in FIG. 6, the first wavelength selection unit 24 has a first-1 wavelength selection region 24a and a first-2 wavelength selection region 24b. The second wavelength selection unit 34 is complementary to the first-1 wavelength selection region 24a and the first-2 wavelength selection region 24b of the first wavelength selection unit 24, and these are designated as a second-1 wavelength selection region 34a and a second-2 wavelength selection region 34b. Further, it is assumed that the first wavelength selection unit 24 is provided with a wavelength shielding unit 25 around the first-1 wavelength selection region 24a and the first-2 wavelength selection region 24b. The wavelength shielding unit 25 is assumed to shield all the light beams emitted from the light source 32.

[0059] In addition, in Fig. 6, the first wavelength selection region 24a and the first wavelength selection region 24b of the first wavelength selection unit 24 are each semi-circular, and when the first wavelength selection region 24a and the first wavelength selection region 24b are combined, they form a circular shape. Although not shown, the second wavelength selection region 34a of the second wavelength selection unit 34 is semi-circular, similar to the first wavelength selection region 24a of the first wavelength selection unit 24, and the second wavelength selection region 34b of the second wavelength selection unit 34 is semi-circular, similar to the first wavelength selection region 24b of the first wavelength selection unit 24, and their adjacent directions are the same along the optical axes L1 and L2.

[0060] At this time, as shown in Fig. 7, if there is an inclination D on the surface of the object S to be inspected, both the first BRDF1 and the second BRDF2 incline in the same direction. Thereby, the first light ray B1 reaches the first wavelength selection region 24b and the wavelength shielding unit 25 of the first wavelength selection unit 24, and passes through the first wavelength selection region 24b. For this reason, in the image sensor 26, the first wavelength is received in the red channel. On the other hand, the second light ray B2 reaches the first wavelength selection region 24b and the shielding unit 25 of the first wavelength selection unit 24, but is shielded there. That is, the light of the second wavelength is not received by the image sensor 26. For this reason, the signal (pixel value) of the blue channel becomes 0. Suppose the inclination D at the object point O is inclined in the opposite direction to that shown in the figure. In that case, due to the same mechanism, only the blue light, which is the light of the second wavelength, is received by the image sensor 26. As described above, by using the wavelength selection unit 24 having anisotropy around the axis of the optical axis L1 and the color image sensor 26, the direction of the inclination can be estimated by identifying whether blue light or red light is received. That is, when there is reception of reflected light from the object S at at least one pixel of the image sensor 26, the processing device (processor) 16 identifies the inclination direction of the surface of the object point O corresponding to that pixel based on the color of the received light.

[0061] The wavelength selection units 24 and 34 are each preferably supported by, for example, a support unit. The support unit can rotate the wavelength selection units 24 and 34 individually or in conjunction, for example, by equal angles. Even when the BRDF has a special anisotropy, an accurate BRDF distribution can be obtained by imaging an image with the image sensor 26 while rotating the wavelength selection units 24 and 34. By rotating the first wavelength selection unit 24 and the second wavelength selection unit 34 by appropriate angles, such as 45° each, around the axes of the optical axes L1 and L2 while maintaining a complementary relationship, and acquiring images respectively, the direction of the inclination D at the object point O of the object S can be estimated.

[0062] As described above, by using the wavelength selection unit 24 having anisotropy around the axis of the optical axis L1 and the color image sensor 26, the direction of the inclination of the surface of the object S can be estimated by identifying whether blue light or red light is received.

[0063] According to this modification example, an optical inspection apparatus 10, a processing apparatus 16, an optical inspection method, and an optical inspection program capable of improving the accuracy of the optical inspection of the surface of the object S can be provided.

[0064] (Example of wavelength selection unit) FIGS. 8 to 12 show various shapes of the first wavelength selection unit 24. The wavelength selection unit 24 can be optimized according to the sensitivity required for optical inspection. Although not shown, the second wavelength selection unit 34 is used such that it maintains a complementary relationship with the first wavelength selection unit 24.

[0065] The first - 1 wavelength selection region 24a of the first wavelength selection unit 24 shown in FIG. 8 is the position excluding the spiral, and the first - 2 wavelength selection region 24b is the position of the spiral. And although not shown, the second - 1 wavelength selection region 34a of the second wavelength selection unit 34 is formed in a similar shape to the position of the first - 1 wavelength selection region 24a excluding the spiral in FIG. 8, and the second - 2 wavelength selection region 34b is formed in a similar shape to the position of the first - 2 wavelength selection region 24b being the position of the spiral in FIG. 8.

[0066] The wavelength selection unit 24 shown in FIG. 9 and the wavelength selection unit 34 (not shown) are arranged in the same relationship as the wavelength selection unit 24 shown in FIG. 2 and the wavelength selection unit 34 shown in FIG. 3. FIG. 9 shows a position where the first wavelength selection region 24a of the first wavelength selection unit 24 excludes the circular ring, and the first wavelength selection region 24b is at the position of the circular ring.

[0067] The first wavelength selection unit 24 in FIG. 10 has four wavelength selection regions 24a, 24b, 24c, and 24d. The wavelength selection unit 24 shown in FIG. 10 and the wavelength selection unit 34 (not shown) are arranged in the same relationship as the wavelength selection unit 24 shown in FIG. 2 and the wavelength selection unit 34 shown in FIG. 3. Although not shown, it is assumed that the second wavelength selection unit 34 has four wavelength selection regions 34a, 34b, 34c, and 34d. Note that the first wavelength selection unit 24 shown in FIG. 10 has anisotropy. Therefore, the first wavelength selection unit 24 shown in FIG. 10 can be used for detecting the inclined surface D (see FIG. 7) described above.

[0068] The first wavelength selection region 24a allows, for example, the first wavelength to pass through and blocks the second to fourth wavelengths that are different from each other. The first wavelength selection region 24b allows, for example, the second wavelength to pass through and blocks the first, third, and fourth wavelengths that are different from each other. The first wavelength selection region 24c allows, for example, the third wavelength to pass through and blocks the first, second, and fourth wavelengths that are different from each other. The first wavelength selection region 24d allows, for example, the fourth wavelength to pass through and blocks the first to third wavelengths that are different from each other.

[0069] Which wavelengths are allowed to pass through and which wavelengths are blocked in each of the wavelength selection regions 34a, 34b, 34c, and 34d of the second wavelength selection unit 34 can be set as appropriate. The second wavelength selection region 34a allows, for example, the fourth wavelength to pass through and blocks the first to third wavelengths that are different from each other. The second wavelength selection region 34b allows, for example, the first wavelength to pass through and blocks the second to fourth wavelengths that are different from each other. The second wavelength selection region 34c allows, for example, the second wavelength to pass through and blocks the first, third, and fourth wavelengths that are different from each other. The second wavelength selection region 34d allows, for example, the third wavelength to pass through and blocks the first, second, and fourth wavelengths that are different from each other.

[0070] The wavelength selection unit 24 shown in FIG. 11 and the wavelength selection unit 34 (not shown) are arranged in the same relationship as the wavelength selection unit 24 shown in FIG. 2 and the wavelength selection unit 34 shown in FIG. 3. The first wavelength selection unit 24 in FIG. 11 has two wavelength selection regions 24a and 24b. The wavelength selection regions 24a and 24b are each in a stripe shape and are adjacent to each other in the vertical direction shown in FIG. 11. Note that the first wavelength selection unit 24 shown in FIG. 11 has anisotropy. For this reason, the first wavelength selection unit 24 shown in FIG. 11 can be used for detecting the inclined surface D described above.

[0071] The wavelength selection unit 24 shown in FIG. 12 and the wavelength selection unit 34 (not shown) are arranged in the same relationship as the wavelength selection unit 24 shown in FIG. 2 and the wavelength selection unit 34 shown in FIG. 3. The first wavelength selection unit 24 in FIG. 12 has three wavelength selection regions 24a and 24b. The first wavelength selection region 24a is disposed between the second wavelength selection regions 24b.

[0072] (Second Embodiment) The optical inspection apparatus 10 according to the present embodiment will be described in detail with reference to FIG. 13. The optical inspection apparatus 10 according to the present embodiment is basically the same as the optical inspection apparatus 10 according to the first embodiment. The differences will be described below.

[0073] In the present embodiment, it is assumed that the image sensor 26 is not a monochrome sensor but a color sensor that can distinguish between blue light, green light, and red light.

[0074] The first wavelength selection unit 24 and the second wavelength selection unit 34 have a complementary relationship with respect to the optical axes L1 and L2. The first wavelength selection unit 24 includes a first - 1 wavelength selection region 24a, a first - 2 wavelength selection region 24b, and a first - 3 wavelength selection region 24c. Assume that the wavelength spectra of the light passing through the respective wavelength selection regions 24a, 24b, and 24c are different from each other. The second wavelength selection unit 34 includes a second - 1 wavelength selection region 34a, a second - 2 wavelength selection region 34b, and a second - 3 wavelength selection region 34c. Assume that the wavelength spectra of the light passing through the respective wavelength selection regions 34a, 34b, and 34c are different from each other.

[0075] The operating principle of the optical inspection apparatus 10 of the present embodiment will be described.

[0076] The light that has passed through the second - 3 wavelength selection region 34c from the light emission point E on the light emission surface of the light source 32 becomes the third light beam B3 including a wavelength of 550 nm and becomes green light. The third light beam B3 passes through the illumination lens 36, is reflected by the beam splitter 38, and reaches the object point O. Further, it is reflected at the object point O and becomes reflected light that can be represented by the third BRDF indicated by reference numeral 3, passes through the beam splitter 38, passes through the imaging lens 22, and reaches the first wavelength selection unit 24.

[0077] If the surface of the specimen S is a mirror surface, the first light beam B1, the second light beam B2, and the third light beam B3 are blocked by the first wavelength selection unit 24. In this case, the image sensor 26 does not receive light at the image point on the image sensor 26. That is, a dark image (pixel value 0) is obtained. At this time, at the image point I on the image sensor 26, none of the blue light, red light, and green light is received, and it means that 0 colors are received. This is defined as the number of colors 0.

[0078] On one hand, when there is unevenness C at object point O, the first light ray B1, the second light ray B2, and the third light ray B3 pass through the first wavelength selection unit 24. Therefore, the image sensor 26 receives three colors of blue light, red light, and green light at the image point I on the image sensor 26. Let this be the number of colors 3. The processing device 16 acquires an image from the image sensor 26 and outputs the number of colors at each pixel. Thereby, the processing device 16 can recognize whether or not three wavelength selection regions 24a, 24b, and 24c among the first wavelength selection unit 24 have been passed through at each pixel.

[0079] The number of colors depends on the width of the BRDF distribution at the object point O. That is, the wider the BRDF distribution, the greater the number of colors detected by the processing device 16, and the narrower the BRDF distribution, the smaller the number of colors detected by the processing device 16. In other words, it is considered that the larger the number of colors, the wider the scattered light distribution (BRDF), and the smaller the number of colors, the narrower the scattered light distribution (BRDF). Therefore, if the number of colors at each image point I can be obtained by the color number estimation process by the processing device 16, the difference in BRDF at each object point O can be identified. That is, the processing device (processor) 16 identifies the difference in surface state based on the number of colors of the received light. For example, when the processing device (processor) 16 receives reflected light from the object S at at least one pixel of the image sensor 26, it recognizes that the surface at the object point O corresponding to that pixel is different from the standard surface.

[0080] However, there are various procedures for counting the number of colors in the processing device 16 depending on how background noise (such as dark current noise, spectroscopic performance of the sensor and wavelength selection region, etc.) is set. For example, depending on the spectroscopic performance of the sensor 26, even though green light has not reached the sensor 26, the electrical signal corresponding to green light may react to red light. Therefore, calibration is performed to offset the background noise and associate the number of colors with the number of wavelength selection units 24, 34 through which the light rays have passed. Through such calibration, the processing device 16 can acquire the accurate number of colors.

[0081] Since the BRDF is correlated with the surface properties and shape, the optical inspection apparatus 10 according to the present embodiment has an effect of being able to identify differences in the surface states of each object point O on the surface of the object S to be inspected.

[0082] According to the present embodiment, it is possible to provide an optical inspection apparatus 10, a processing apparatus 16, an optical inspection method, and an optical inspection program capable of improving the accuracy of the optical inspection of the surface of the object S to be inspected.

[0083] (Third Embodiment) The optical inspection apparatus 10 according to the present embodiment will be described in detail with reference to FIG. 14. The optical inspection apparatus 10 according to the present embodiment is basically the same as the optical inspection apparatus 10 according to the first embodiment. The differences will be described below.

[0084] In the present embodiment, as shown in FIGS. 14 and 15, the second wavelength selection unit 34 further includes, for example, a strip-shaped wavelength shielding unit 35.

[0085] The width (line width) W of the band of the wavelength shielding unit 35 shown in FIG. 15 is defined as the shielding width.

[0086] Assume that the standard surface of the object S shown in FIG. 14 is a mirror surface, and the BRDF at the object point O on the standard surface consists only of the specular reflection component. At this time, when the shielding width W shown in FIG. 15 is 0 (there is no wavelength shielding portion 35), if the BRDF spreads due to the presence of unevenness C on the surface of the object S, etc., light reception immediately occurs at the image sensor 26. That is, when the shielding width W is 0 (there is no wavelength shielding portion 35), it can be said that the sensitivity to the difference in the BRDF distribution is very high. On the other hand, as the shielding width W shown in FIG. 15 is increased, a state can be realized in which there is no light ray passing through the first wavelength selection portion 24 even if the BRDF spreads slightly. That is, the sensitivity to the difference in the BRDF distribution can be weakened. This has the advantage, for example, that when the standard surface of the object S has a slight diffusivity and the BRDF spreads slightly, the reception of the reflected light from the standard surface can be completely shielded, and the S / N can be increased. Thus, by providing the second wavelength selection portion 34 with the wavelength shielding portion 35 and making the shielding width W of the wavelength shielding portion 35 adjustable, the sensitivity to the difference in the BRDF can be adjusted.

[0087] According to the optical inspection apparatus 10 according to the present embodiment, since the wavelength shielding portion 35 is provided with the wavelength shielding portion 35 and the shielding width W is adjusted according to the BRDF, there is an advantage that the S / N for defect detection such as the unevenness C on the surface of the object S can be adjusted.

[0088] Note that by electromagnetically adjusting the shielding width W of the shielding portion 35, the number of lineups of the second wavelength selection portion 34 can be reduced.

[0089] In the present embodiment, an example in which the second wavelength selection portion 34 includes the shielding portion 35 has been described. The first wavelength selection portion 24 may have a shielding portion corresponding to the shielding portion 35 between the first wavelength selection region 24a and the second wavelength selection region 24b. In this case, the shielding portion 35 may not be provided.

[0090] According to the present embodiment, it is possible to provide an optical inspection apparatus 10, a processing apparatus 16, an optical inspection method, and an optical inspection program capable of highly accurate optical inspection of the surface of the object S.

[0091] (Fourth Embodiment) The optical inspection apparatus 10 according to this embodiment will be described in detail with reference to FIG. 16. This embodiment is basically the same as the optical inspection apparatus 10 according to the first embodiment. The differences will be described below.

[0092] The light source 32 of the illumination unit 14 is an LED. The illumination unit 14 includes a pinhole aperture 40 on the focal plane F2 of the illumination lens 36. The hole diameter of the pinhole aperture 40 is, for example, 0.4 mm. With such a configuration, parallel light can be irradiated from the illumination unit 14. The parallel light passes through the second wavelength selection unit 34 and is irradiated onto the surface of the object S via the beam splitter 38. Note that the second wavelength selection unit 34 of the optical inspection apparatus 10 according to this embodiment is disposed closer to the object S than the illumination lens 36 on the optical path. The arrangement of the second wavelength selection unit 34 is the same as the arrangement of the second wavelength selection unit 34 of the optical inspection apparatus 10 (see FIG. 13) according to the second embodiment.

[0093] The first wavelength selection unit 24 of the optical inspection apparatus 10 according to this embodiment is disposed between the imaging unit 12 and the object S. The first wavelength selection unit 24 is disposed closer to the object S than the imaging lens 22. That is, the first wavelength selection unit 24 is disposed at a location that is not the focal plane of the imaging lens 22. The arrangement of the first wavelength selection unit 24 is different from the arrangement of the first wavelength selection unit 24 of the optical inspection apparatus 10 (see FIG. 13) according to the second embodiment. In the cross section shown in FIG. 16, the arrangement of the first wavelength selection unit 24 is horizontally inverted from the arrangement of the first wavelength selection unit 24 in the cross section shown in FIG. 13. And it is assumed that the first wavelength selection unit 24 and the second wavelength selection unit 34 have complementarity with each other.

[0094] The operating principle of the optical inspection apparatus 10 according to this embodiment will be described.

[0095] It is assumed that the standard surface of the surface of the object S is a mirror surface. According to this embodiment, all the light reflected by the standard surface is blocked by the first wavelength selection unit 24. This is because the first wavelength selection unit 24 and the second wavelength selection unit 34 have complementarity with each other.

[0096]

[0097]

[0098]

[0099] (Fifth Embodiment)

[0100] The illumination unit 14 includes a light source (LED) 32, an aperture 40 (see FIG. 16), an illumination lens 36 (see FIG. 16), and a second wavelength selection unit 34. The aperture 40 is assumed to be slit-shaped. Here, for example, the slit width is 0.4 mm and the length in the longitudinal direction is 300 mm. A plurality of light sources 32 having a light emitting surface of 1.0 mm × 3.0 mm, for example, are arranged along the longitudinal direction of the slit of the aperture 40. The illumination lens 36 is a cylindrical lens and is assumed to have a length of 300 mm in the longitudinal direction. The focal length is, for example, 50 mm. The slit-shaped aperture 40 is disposed on the focal plane F2 of the illumination lens 36. With such a configuration, the light from the illumination unit 14 forms a line beam. Therefore, the light from the illumination unit 14 becomes parallel light in the first cross section S1 orthogonal to the slit-shaped aperture 40. On the other hand, the light from the illumination unit 14 becomes diffused light in the light rays orthogonally projected (orthographically projected) onto the second cross section S2 orthogonal to the first cross section S1.

[0101] The first wavelength selection unit 24 and the second wavelength selection unit 34 are stripe-shaped and have complementarity with each other.

[0102] The illumination unit 14 and the imaging unit 12 are arranged such that the optical axis L2 of the illumination lens of the illumination unit 14 and the optical axis L1 of the imaging lens 22 are in a specular reflection positional relationship with respect to the surface of the object S (object). Here, note that a beam splitter 38 is not used.

[0103] In FIG. 17, the first cross section S1 is assumed to include the optical axes L1 and L2, and the light from the illumination unit 14 is parallel light. On the other hand, a cross section orthogonal to the first cross section S1 is defined as the second cross section S2. In the light rays orthogonally projected (orthographically projected) onto the second cross section S2, the light from the illumination unit 14 is not parallel light but diffused light.

[0104] The first wavelength selection unit 24 includes three wavelength selection regions 24a, 24b, and 24c, and the second wavelength selection unit 34 includes three wavelength selection regions 34a, 34b, and 34c. Each of the three wavelength selection regions 24a, 24b, 24c, 34a, 34b, and 34c is assumed to be stripe-shaped.

[0105] In the first cross-section S1 or a cross-section parallel thereto, a plurality of wavelength selection regions 24a, 24b, 24c of the first wavelength selection unit 24 and a plurality of wavelength selection regions 34a, 34b, 34c of the second wavelength selection unit 34 are arranged. That is, on the first cross-section S1, the direction in which the plurality of wavelength selection regions 24a, 24b, 24c, 34a, 34b, 34c are arranged is included. On the other hand, in the second cross-section S2 orthogonal to the first cross-section S1 or a cross-section parallel thereto, the plurality of wavelength selection regions 24a, 24b, 24c, 34a, 34b, 34c do not change.

[0106] The illumination unit 14 irradiates the surface of the object S to be inspected and forms an irradiation field F that changes color in a stripe shape.

[0107] In the first cross-section S1, the spread of the BRDF1 distribution can be identified by the number of colors of the light that has passed through the wavelength selection regions 24a, 24b, 24c of the wavelength selection unit 24. However, since the light from the illumination unit 14 is parallel light, the angle of view in the direction corresponding to this cross-section S1 becomes narrow in the imaging unit 12. That is, the imaging range in this direction is narrow. On the other hand, in the second cross-section S2 or a cross-section parallel thereto, the number of colors is constant. This is because in this cross-section S2 or a cross-section parallel thereto, the wavelength selection regions 24a, 24b, 24c of the first wavelength selection unit 24 and the wavelength selection regions 34a, 34b, 34c of the second wavelength selection unit 34 do not change. However, since the light from the illumination unit 14 is diffused light in the light rays orthogonally projected onto this cross-section S2, the angle of view in the direction corresponding to this cross-section S2 becomes wide in the image acquired by the imaging unit 12. As described above, in the acquired image, for two directions orthogonal to the optical axes L1, L2, the angle of view is narrow in one direction, but can be widened in the direction orthogonal thereto. Also, the number of colors at the image point I is the number of wavelength selection regions 24a, 24b, 24c when the light ray passes through the wavelength selection unit 24 in the first cross-section S1.

[0108] As a result, compared with the case where the light from the illumination unit 14 is made completely parallel light, there is an effect that the overall angle of view can be widened. Also, by forming the wavelength selection region in a stripe shape, there is an effect that the overall angle of view can be widened compared to the case where it is not.

[0109] Also, similar to the optical inspection device 10 (see FIG. 16) according to the fourth embodiment, by arranging the first wavelength selection unit 24 in front of the imaging unit 12, this optical system can be assembled for any imaging unit (that is, camera) 12. That is, the selection range of the camera can be widened by this configuration. That is, there is an effect that the wavelength selection unit 24 can be easily arranged by the light that has passed through the wavelength selection unit 24 passing through the imaging lens 22 for imaging.

[0110] According to the present embodiment, it is possible to provide an optical inspection device 10, a processing device 16, an optical inspection method, and an optical inspection program capable of highly accurate optical inspection of the surface of the object to be inspected S.

[0111] According to at least one of the embodiments described above, it is possible to provide an optical inspection device 10, a processing device 16, an optical inspection method, and an optical inspection program capable of highly accurate optical inspection of the surface of the object to be inspected S.

[0112] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and its equivalent scope. Append the claims at the time of patent application of this application. [Appendix 1] An imaging unit including an image sensor capable of imaging the object to be inspected with light from the object to be inspected, a first wavelength selection unit provided on the optical axis of the imaging unit and selectively passing light of a plurality of predetermined wavelengths, an illumination unit for illuminating the object to be inspected, a second wavelength selection unit provided on the optical axis of the illumination unit and passing light of a plurality of predetermined wavelengths complementarily to the first wavelength selection unit An optical inspection device comprising. [Appendix 2] The first wavelength selection unit includes a first-1 region that shields light of the first wavelength and allows light of a second wavelength different from the first wavelength to pass through toward the image sensor, and a first-2 region that allows light of the first wavelength to pass through toward the image sensor and shields light of the second wavelength. The second wavelength selection unit is similar in shape to the first - 1 region, and includes a second - 1 region that allows light of the first wavelength to pass through toward the object to be inspected and blocks light of the second wavelength, and a second - 2 region that is similar in shape to the first - 2 region, allows light of the second wavelength to pass through toward the object to be inspected, and blocks light of the first wavelength. The optical inspection device according to Supplementary Note 1. [Supplementary Note 3] The optical inspection device according to Supplementary Note 1 or Supplementary Note 2, wherein at least one of the first wavelength selection unit and the second wavelength selection unit has a wavelength blocking unit. [Supplementary Note 4] Assume that the wavelength blocking unit is strip - shaped, the width of the strip is defined as the blocking width, and the blocking width is adjustable. The optical inspection device according to Supplementary Note 3. [Supplementary Note 5] The imaging unit includes a first imaging optical element. The illumination unit includes a second imaging optical element. The first wavelength selection unit is disposed on the focal plane of the first imaging optical element and has anisotropy with respect to the optical axis of the imaging unit. The second wavelength selection unit is disposed on the focal plane of the second imaging optical element and has anisotropy with respect to the optical axis of the illumination unit. The optical inspection device according to any one of Supplementary Notes 1 to 4. [Supplementary Note 6] The imaging unit includes a first imaging optical element. The first wavelength selection unit is disposed on the focal plane of the first imaging optical element of the imaging unit or in the vicinity thereof. The illumination unit includes a second imaging optical element. The second wavelength selection unit is disposed on the focal plane of the second imaging optical element of the illumination unit or in the vicinity thereof. The optical inspection device according to any one of Supplementary Notes 1 to 4. [Supplementary Note 7] Assume that the illumination unit irradiates the object to be inspected with parallel light. The first wavelength selection unit is disposed between the imaging unit and the object to be inspected. The optical inspection device according to any one of Supplementary Notes 1 to 5. [Supplementary Note 8] A beam splitter is provided between the object to be inspected and the imaging unit. The beam splitter is a polarization beam splitter. The optical inspection device according to any one of Supplementary Notes 1 to 7. [Supplementary Note 9] In each pixel of the image sensor of the optical inspection device according to any one of Supplementary Notes 1 to 8, detect the presence or absence of reception of reflected light from the object to be inspected. In each pixel of the image sensor, when the detection result indicates no light reception, output that the object point of the object to be inspected corresponding to the pixel is on the standard surface, and when the detection result indicates light reception, output that the object point of the surface of the object to be inspected corresponding to the pixel is on a surface different from the standard surface. A processing device including a processor. [Appendix 10] In each pixel of the image sensor of the optical inspection device according to any one of Appendices 1 to 8, detect the presence or absence of reception of reflected light from the object to be inspected. In each pixel of the image sensor, when the detection result indicates no light reception, output that the object point of the object to be inspected corresponding to the pixel is on a surface different from the standard surface, and when the detection result indicates light reception, output that the object point of the surface of the object to be inspected corresponding to the pixel is on the standard surface. A processing device including a processor. [Appendix 11] An optical inspection method for inspecting the surface of an object to be inspected using the optical inspection device according to any one of Appendices 1 to 8, comprising: In each pixel of the image sensor, detect the presence or absence of reception of reflected light from the object to be inspected. In each pixel of the image sensor, based on the detection result of the presence or absence of light reception, output the difference between the surface at the object point corresponding to the pixel and the standard surface. Optical inspection method. [Appendix 12] Identify the difference in surface state based on the number of colors received in at least one pixel of the image sensor. The optical inspection method according to Appendix 11. [Appendix 13] An optical inspection program for inspecting the surface of an object to be inspected using the optical inspection device according to any one of Appendices 1 to 8, comprising: In each pixel of the image sensor, a process of detecting the presence or absence of reception of reflected light from the object to be inspected; and In each pixel of the image sensor, a process of outputting the difference between the surface at the object point corresponding to the pixel and the standard surface based on the detection result of the presence or absence of light reception. An optical inspection program that causes a processor to execute the above processes.

Explanation of Symbols

[0113] 10…Optical inspection device, 12…Imaging unit, 14…Illumination unit, 16…Processing device, 22…Imaging optical element, 24…First wavelength selection unit, 24a…First-1 wavelength selection region, 24b…First-2 wavelength selection region, 26…Sensor (image sensor), 32…Light source, 34…Second wavelength selection unit, 34a…Second-1 wavelength selection region, 34b…Second-2 wavelength selection region, 36…Illumination lens, 38…Beam splitter.

Claims

1. An imaging unit including an image sensor capable of imaging the object with light from the object; A first wavelength selection unit provided on the optical axis of the imaging unit and allowing light of a wavelength selected from a plurality of predetermined wavelengths to pass therethrough; An illumination unit for illuminating the object; A second wavelength selection unit provided on the optical axis of the illumination unit and allowing light of a wavelength selected from the plurality of predetermined wavelengths to pass therethrough; Characterized by comprising: The first wavelength selection unit includes a first-1 region that shields light of a first wavelength and allows light of a second wavelength different from the first wavelength to pass toward the image sensor, and a first-2 region that allows light of the first wavelength to pass toward the image sensor and shields light of the second wavelength; The second wavelength selection unit includes a second-1 region that is similar to the first-1 region, allows light of the first wavelength to pass toward the object, and shields light of the second wavelength, and a second-2 region that is similar to the first-2 region, allows light of the second wavelength to pass toward the object, and shields light of the first wavelength; Among the pixels of the image sensor, at a first position where light from the object is received, both light of the first wavelength and light of the second wavelength are received simultaneously; Among the pixels of the image sensor, at a second position where light from the object is not received, neither light of the first wavelength nor light of the second wavelength is received; It is possible to create contrast with light of at least two different wavelengths from the object between the first position and the second position in the pixels of the image sensor; An optical inspection device.

2. The optical inspection device according to claim 1, wherein at least one of the first wavelength selection unit and the second wavelength selection unit has a wavelength shielding portion.

3. The wavelength shielding portion is strip-shaped, the width of the strip is defined as the shielding width, and the shielding width is adjustable; The optical inspection device according to claim 2.

4. The imaging unit includes a first imaging optical element; The illumination unit includes a second imaging optical element; The first wavelength selection unit is disposed on the focal plane of the first imaging optical element and has anisotropy with respect to the optical axis of the imaging unit; The second wavelength selection unit is disposed on the focal plane of the second imaging optical element and has anisotropy with respect to the optical axis of the illumination unit; The optical inspection device according to any one of claims 1 to 3.

5. The imaging unit includes a first imaging optical element. The first wavelength selection unit is disposed on or near the focal plane of the first imaging optical element of the imaging unit. The illumination unit includes a second imaging optical element. The second wavelength selection unit is disposed on or near the focal plane of the second imaging optical element of the illumination unit. The optical inspection apparatus according to any one of claims 1 to 3.

6. The illumination unit can irradiate the object to be inspected with parallel light. The first wavelength selection unit is disposed between the imaging unit and the object to be inspected. The optical inspection apparatus according to any one of claims 1 to 4.

7. A beam splitter is provided between the object to be inspected and the imaging unit. The beam splitter is a polarization beam splitter. The optical inspection apparatus according to any one of claims 1 to 6.

8. The first wavelength selection unit and the second wavelength selection unit have anisotropy around the axis of the optical axis of the imaging unit. The optical inspection apparatus according to any one of claims 1 to 7.

9. An optical inspection method for inspecting the surface of an object to be inspected using the optical inspection apparatus according to any one of claims 1 to 8, In each pixel of the image sensor, at the first position where light from the object to be inspected is received, both the light of the first wavelength and the light of the second wavelength are received simultaneously, and at the second position where light from the object to be inspected is not received, neither the light of the first wavelength nor the light of the second wavelength is received. Between the first position and the second position in the pixel of the image sensor, the presence or absence of reception of reflected light from the object to be inspected is detected as a detection result by the output of contrast formed by light of at least two different wavelengths from the object to be inspected. In each pixel of the image sensor, based on the detection result of the presence or absence of reception of light, the difference between the surface at the object point corresponding to the pixel and the standard surface is output. Optical inspection method.

10. The difference in surface state is identified by the number of colors received in at least one pixel of the image sensor. The optical inspection method according to claim 9.

Images