Optical inspection device, method, and program

Abstract

To provide an optical inspection device with which it is possible to measure information pertaining to a specimen with high accuracy.SOLUTION: An optical inspection device of an embodiment of the present invention includes a first optical system, a second optical system, and an imaging element. The first optical system passes a beam of light of a first wavelength through and has telecentricity on an object side with respect to the beam of light of the first wavelength. The second optical system passes a beam of light of a second wavelength through that is different from the first wavelength. The imaging element is capable of imaging the object on the basis of the beam of light of the first wavelength having passed through the first optical system and the beam of light of the second wavelength having passed through the second optical system.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Non-contact inspection technology is becoming increasingly important in a variety of industries. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Walton L. Howes, “Rainbow schlieren and its applications”, Appl. Optics, vol.23, No.14, 1984. [Non-patent document 2] JS Kim and T. Kanade, “Multiaperture telecentric lens for 3D reconstruction”, Optics Letters, vol. 36, No. 7, 2011. Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide an optical inspection device, method, and program that can measure information related to an object to be inspected with high accuracy. [Means for solving the problem]

[0005] The optical inspection device according to this embodiment includes a first optical system, a second optical system, an image sensor, and a processing circuit. The first optical system includes a first wavelength-selective filter that transmits light rays of a first wavelength and is telecentric on the object side with respect to the light rays of the first wavelength. The second optical system includes a second wavelength-selective filter that transmits light rays of a second wavelength different from the first wavelength. The first wavelength-selective filter and the second wavelength-selective filter are arranged in a common filter and are non-telecentric on the object side with respect to the light rays of the second wavelength. The image sensor is capable of capturing an image of the object based on the light rays of the first wavelength that have passed through the first optical system from an object point on the object and the light rays of the second wavelength that have passed through the second optical system from the object point. The processing circuit separates the image data from the image sensor into color-separated image data for each color, and measures the surface condition of the object based on scattering information composed of at least the light rays of the first wavelength and the light rays of the second wavelength at the object point from the image data for each color. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of an optical inspection system according to the first embodiment. [Figure 2] FIG. 2 is an xz cross-sectional view showing an example of the configuration of the optical device according to the first embodiment. [Figure 3] FIG. 3 is a bird's-eye view showing an outline of an example of the configuration of the optical device according to the first embodiment. [Figure 4] FIG. 4 is a side view showing an outline of an example of the configuration of the optical device according to the first embodiment. [Figure 5] FIG. 5 is a schematic diagram showing an example of an xy cross section of an opening of the first color filter according to the first embodiment. [Figure 6] FIG. 6 is a flowchart illustrating an example of the calculation process according to the first embodiment. [Figure 7] FIG. 7 is a block diagram showing an example of the configuration of a processing circuit according to the second embodiment. [Figure 8]FIG. 8 is an xz cross-sectional view showing an example of the configuration of the optical device according to the second embodiment. [Figure 9] FIG. 9 is a schematic diagram showing an example of an xy cross section of an opening of the second color filter according to the second embodiment. [Figure 10] FIG. 10 is a schematic diagram showing an example of an xy cross section of an opening of a first color filter according to the second embodiment. [Figure 11] FIG. 11 is a flowchart illustrating an example of the calculation process according to the second embodiment. [Figure 12] FIG. 12 is a diagram for explaining object points in the actual measurement evaluation according to the second embodiment. [Figure 13A] FIG. 13A is an image acquired in an actual measurement evaluation in which the diaphragm was placed at a position 160 mm away from the first lens on the −z side. [Figure 13B] FIG. 13B is an image acquired in an actual measurement evaluation in which the diaphragm was placed at a position 210 mm away from the first lens on the −z side. [Figure 13C] FIG. 13C is an image acquired in an actual measurement evaluation in which the diaphragm was placed at a position 225 mm away from the first lens on the −z side. [Figure 14] FIG. 14 is a graph showing the results of actual measurement evaluation according to the second embodiment. [Figure 15] FIG. 15 is an xz cross-sectional view showing an example of the configuration of the optical device according to the third embodiment. [Figure 16] FIG. 16 is an xz cross-sectional view showing an example of the configuration of the optical device according to the fourth embodiment. [Figure 17] FIG. 17 is a schematic diagram showing an example of an xy cross section of an aperture of the first wavelength-selective filter according to the fourth embodiment. [Figure 18] FIG. 18 is a schematic diagram showing an example of an xy cross section of an aperture of an aperture stop according to the fourth embodiment. [Figure 19] FIG. 19 is a schematic diagram showing an example of an xy cross section of an aperture of the second wavelength-selective filter according to the fourth embodiment. [Figure 20]FIG. 20 is a schematic diagram showing an example of an xy cross section of an aperture of a first wavelength-selective filter according to a modified example of the fourth embodiment. [Figure 21] FIG. 21 is an xz cross-sectional view showing an example of the configuration of the optical device according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc., are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In this specification and each drawing, elements similar to those previously described with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions will be omitted as appropriate.

[0008] The light or light rays in the description of each embodiment are not limited to visible light or visible light rays, but the following description will be given taking as an example a case where white light is used as ambient light.

[0009] (First embodiment) First, the configuration of an optical inspection system 1 according to this embodiment will be described in detail with reference to the drawings.

[0010] Fig. 1 is a block diagram showing an example of the configuration of an optical inspection system 1 according to this embodiment. As shown in Fig. 1, the optical inspection system 1 includes an optical inspection device 10 and a display 90. The optical inspection device 10 includes an optical device 20, a processing circuit 70, and a memory 80. The optical device 20 includes an optical system 30 and an image sensor 60.

[0011] FIG. 2 is an xz cross-sectional view showing an example of the configuration of the optical device 20 according to this embodiment. FIG. 3 is a bird's-eye view showing an outline of the configuration example of the optical device 20 according to this embodiment. FIG. 4 is a side view showing an outline of the configuration example of the optical device 20 according to this embodiment. Note that FIGS. 2, 3, and 4 schematically show an example of the ray path of a light ray emitted from an object point O. As shown in FIGS. 2, 3, and 4, the optical system 30 includes a first lens 311 and a first color filter 313.

[0012] In this embodiment, the x-axis, y-axis, and z-axis are defined as follows: The z-axis is the optical axis of the first lens 311. The +z direction is the direction from the first lens 311 toward the imaging surface 61 of the image sensor 60. The x-axis and y-axis are perpendicular to each other and perpendicular to the z-axis. The -x direction is, for example, the direction of gravity. Here, for example, in the xz cross-sectional view of the optical device 20 shown in FIG. 2, the +z direction is the direction from left to right, the -x direction is the direction from top to bottom, and the +y direction is the direction from back to front perpendicular to the plane of the page.

[0013] The first lens 311 focuses light rays emitted from an object point O on the test object onto an image point on the imaging surface 61 of the imaging element 60. The test object is an example of an object. The first lens 311 is an example of a shared lens. The image-side focal length f of the first lens 311 is a focal length f1. The first lens 311 is formed of, for example, optical glass, but is not limited to this. The first lens 311 may be formed of, for example, optical plastic such as acrylic resin (Polymethyl methacrylate: PMMA) or polycarbonate (Polycarbonate: PC). The first lens 311 may be a single lens or an optical system combining multiple lenses.

[0014] The first color filter 313 is disposed at the image-side focal point of the first lens 311. In other words, the first color filter 313 is disposed at a position on the +z side of the first lens 311, a distance of focal length f1. The first color filter 313 limits the solid angle of the light beam passing through the first lens 311, with the +z-axis direction being the zenith direction. The aperture of the first color filter 313 can also be expressed as being located on the image-side focal plane of the first lens 311. The first color filter 313 includes a support member and a wavelength-selecting member (not shown). The support member has an aperture. The wavelength-selecting member is provided in the aperture of the support member. The center of the wavelength-selecting member is located on the z-axis. The wavelength-selecting member has the property of transmitting light of a specific wavelength spectrum. Note that transmission may also be expressed as passing. The wavelength-selecting member is, for example, a color filter.

[0015] The wavelength selection member may include a transparent member that transmits light rays of any wavelength in the visible light range, and a black member that does not transmit light rays of any wavelength in the visible light range. The transparent member can also be expressed as transmitting white light (visible light). The transparent member does not necessarily have to be provided.

[0016] The configuration of the first color filter 313 will now be described in more detail. FIG. 5 is a schematic diagram showing an example of an xy cross section of the aperture of the first color filter 313 according to this embodiment. As shown in FIG. 5, the outer shapes of the aperture and wavelength-selecting member of the first color filter 313 are, for example, circular, but may also be polygonal. The wavelength-selecting member of the first color filter 313 has multiple wavelength-selecting regions. In this embodiment, the multiple wavelength-selecting regions are arranged, for example, in a concentric circle shape. The radii of the concentric circles defining the wavelength-selecting regions are denoted as r0, r1, and r2, starting from the outside. As shown in FIG. 5, the wavelength-selecting region of the first color filter 313 is divided into three concentric regions: a first region A1, a second region A2, and a third region A3, starting from the outside.

[0017] The first region A1 is a region from radius r1 to radius r0. A green transmission filter that transmits green light is provided in the first region A1. The green transmission filter is an example of a third wavelength selection filter. In other words, the first region A1 of the first color filter 313 is a region that transmits green light. In the drawings, the region hatched with diagonal dashed lines is a region that transmits green light.

[0018] The second region A2 is a region from radius r2 to radius r1. A red transmission filter that transmits red light is provided in the second region A2. The red transmission filter is an example of a second wavelength selection filter. In other words, the second region A2 of the first color filter 313 is a region that transmits red light. In the drawing, the region with grid-like hatching is a region that transmits red light.

[0019] The third region A3 is a region with a radius of r2 or less. A blue transmission filter that transmits blue light is provided in the third region A3. The blue transmission filter is an example of a first wavelength selection filter. In other words, the third region A3 of the first color filter 313 is a region that transmits blue light. In the drawings, the region with dotted hatching is a region that transmits blue light.

[0020] In this manner, the first wavelength-selective filter, the second wavelength-selective filter, and the third wavelength-selective filter are integrally configured as a first color filter 313. In this case, each wavelength-selective filter is arranged rotationally symmetrically with respect to the optical axis of the first lens 311. Furthermore, the first wavelength-selective filter is arranged on the ray path of a ray whose chief ray passes through the image-side focal point of the first lens 311. Here, the blue ray has, for example, a peak wavelength of 450 nm in its wavelength spectrum. The wavelength of the ray representing blue is an example of a first wavelength. Furthermore, the red ray has, for example, a peak wavelength of 650 nm in its wavelength spectrum. The wavelength of the ray representing red is an example of a second wavelength. Furthermore, the green ray has, for example, a peak wavelength of 530 nm in its wavelength spectrum. The wavelength of the ray representing green is an example of a third wavelength.

[0021] The optical system 30 according to this embodiment can be expressed as including a telecentric optical system 40 and a non-telecentric optical system 50. The telecentric optical system 40 is an example of a first optical system. The non-telecentric optical system 50 is an example of a second optical system. The telecentric optical system 40 includes a first lens 311 and a first color filter 313. The telecentric optical system 40 is an optical system that is telecentric with respect to blue light rays. The telecentric optical system 40 is an object-side telecentric optical system. In an object-side telecentric optical system, the entrance pupil is located at infinity, and the optical axis and the chief ray are parallel in object space. The object-side telecentric optical system may also be expressed as an object-side telecentric optical system. The non-telecentric optical system 50 includes the first lens 311 and a first color filter 313. The non-telecentric optical system 50 is an optical system that passes blue light rays. The non-telecentric optical system 50 is an optical system that does not have telecentricity with respect to blue light rays. In other words, it can be said that the telecentric optical system 40 and the non-telecentric optical system 50 share at least one lens. In this case, the shared lens is, for example, the first lens 311, which is arranged on the optical axis of the telecentric optical system 40. Furthermore, as shown in FIG. 2, the optical axis of the telecentric optical system 40 and the optical axis of the non-telecentric optical system 50 are coaxial.

[0022] A non-telecentric optical system is an optical system that does not have telecentricity, such as an entcentric optical system, a magnifying optical system, or a reducing optical system.

[0023] The image sensor 60 is disposed on the +z side of the image-side focal point of the first lens 311. The optical path length L between the image sensor surface 61 of the image sensor 60 and the image-side principal point of the first lens 311 is optical path length L1. The image sensor surface 61 of the image sensor 60 is located at the image forming plane of the first lens 311. In other words, the image sensor surface 61 of the image sensor 60 is disposed on the -z side of the first color filter 313. The image sensor 60 is, for example, a charge-coupled device (CCD). The image sensor 60 is, for example, a single-chip color CCD, but may also be a three-chip color CCD. The image sensor 60 outputs the received light intensity for each pixel for light rays incident on the image sensor surface 61. In other words, the image sensor 60 outputs the received light position and received light intensity of light rays incident on the image sensor surface 61. The image sensor 60 is not limited to a CCD, but may be an image sensor such as a complementary metal-oxide semiconductor (CMOS), or may be a light receiving element. The image sensor 60 can be expressed as being capable of capturing an image of an object based on light rays that have passed through the telecentric optical system 40 and light rays that have passed through the non-telecentric optical system 50. The image sensor 60 can also be expressed as being capable of capturing, among light rays emitted from the object point O, light rays that have passed through the telecentric optical system 40 and light rays that have passed through the non-telecentric optical system 50. The image sensor 60 can also be expressed as being configured to capture, coaxially, among light rays emitted from the object point O, light rays that have passed through the telecentric optical system 40 and light rays that have passed through the non-telecentric optical system 50.

[0024] The processing circuit 70 is an integrated circuit such as a central processing unit (CPU) or an application-specific integrated circuit (ASIC). A general-purpose computer may be used as the processing circuit 70. The processing circuit 70 is not limited to being provided as a dedicated circuit, but may also be provided as a program executed by a computer. In this case, the program is recorded in a storage area within the integrated circuit, a memory 80, or the like. The processing circuit 70 is connected to the image sensor 60 and the memory 80. The processing circuit 70 calculates information related to the test object based on the output of the image sensor 60. The information related to the test object is an example of information related to the object. The processing circuit 70 functions as a color extraction unit 71 and a scattering angle calculation unit 72. The color extraction unit 71 acquires the intensity of each RGB of the light reaching the imaging surface based on the output of the image sensor 60. The color extraction unit 71 separates the image data output by the image sensor 60 into color data for each color. The color extraction unit 71 is an example of a generation unit. The scattering angle calculation unit 72 calculates information related to the test object including the object point O based on the image data for each color. Specifically, the scattering angle calculation unit 72 identifies the color of the captured light beam based on the image data for each color. The scattering angle calculation unit 72 calculates the scattering angle of the ambient light at the object point O of the test object based on the color of the captured light beam, i.e., the intensity of each RGB of the light beam that reached the imaging plane 61. The scattering angle calculation unit 72 is an example of a calculation unit. The scattering angle at the object point O of the test object is an example of information related to the test object.

[0025] The processing circuit 70 may be located outside the optical inspection device 10. In this case, the output of the image sensor 60 may be output to the outside of the optical inspection device 10 or recorded in the memory 80. In other words, the calculation of information related to the test object may be performed inside or outside the optical inspection device 10.

[0026] The memory 80 stores the output of the image sensor 60 or the processing circuit 70. The memory 80 stores information such as the focal length f1 of the first lens 311, the distance between the first lens 311 and the image pickup surface 61, and the layout of the multiple wavelength selection regions of the first color filter 313. The memory 80 may also store in advance the relationship between the intensity of each of the R, G, and B light beams and the scattering angle. The memory 80 is a non-volatile memory such as a flash memory, but may also include a volatile memory.

[0027] The display 90 displays the output of the processing circuit 70. The output of the processing circuit 70 includes, for example, an image based on the image data output by the imaging element 60, an operation screen, etc. The display 90 is, for example, a liquid crystal display or an organic EL display. Note that the display 90 does not necessarily have to be provided. In this case, the output of the processing circuit 70 may be recorded in the memory 80, displayed on a display provided outside the optical inspection system 1, or recorded in a memory provided outside the optical inspection system 1.

[0028] Next, the operation of the optical inspection system 1 according to this embodiment will be described in detail with reference to the drawings. In the following description, the light beam emitted from an arbitrary object point O on the test object is ambient light scattered at the arbitrary object point O on the test object. It is assumed that the ambient light is white light.

[0029] First, a light ray emitted from an arbitrary object point O and incident on the first lens 311 will be described. Fig. 2 shows, as examples of light rays, light ray B whose chief ray is parallel to the optical axis when incident on the first lens 311, light ray R whose chief ray is inclined at θr with respect to the optical axis, and light ray G whose chief ray is inclined at θg with respect to the optical axis. Note that Fig. 2 shows only the chief ray of light ray R and light ray G. In the drawing, light ray B, which is imaged as a blue light ray, is shown with a dashed line, light ray R, which is imaged as a red light ray, is shown with a dashed line, and light ray G, which is imaged as a green light ray, is shown with a dashed line.

[0030] Light ray B is a light ray that passes through the first lens 311 and then enters the third region A3 of the first color filter 313. Here, the aperture surface of the first color filter 313 is disposed on the image-side focal plane of the first lens 311. Furthermore, the third region A3 is provided at the center of the aperture surface of the first color filter 313. Of the light rays B that enter the third region A3 of the first color filter 313, blue light ray B can pass through the first color filter 313. The blue light ray B that exits the first color filter 313 enters the imaging plane 61. In this way, of the light rays that are emitted from an arbitrary object point O and enter the first lens 311, light ray B that is parallel to the optical axis of the first lens 311 reaches the imaging plane 61 as blue light ray B.

[0031] Light ray R is a light ray that passes through the first lens 311 and then enters the second region A2 of the first color filter 313. Here, the second region A2 is located outside the third region A3 of the first color filter 313 and is a concentric region coaxial with the third region A3. Of the light rays R that enter the second region A2 of the first color filter 313, red light ray R can pass through the first color filter 313. The red light ray R that exits the first color filter 313 enters the imaging plane 61. In this way, of the light rays that exit from an arbitrary object point O and enter the first lens 311, light ray R that is inclined by θr with respect to the optical axis of the first lens 311 reaches the imaging plane 61 as red light ray R.

[0032] Light ray G is a light ray that passes through the first lens 311 and then enters the first region A1 of the first color filter 313. Here, the first region A1 is further outward than the second region A2 of the first color filter 313 and is a concentric region coaxial with the third region A3 and the second region A2. Of the light rays G that enter the first region A1 of the first color filter 313, green light ray G can pass through the first color filter 313. Green light ray G that exits the first color filter 313 enters the imaging plane 61. Thus, of the light rays that exit from an arbitrary object point O and enter the first lens 311, light ray G that is inclined by θg with respect to the optical axis of the first lens 311 reaches the imaging plane 61 as green light ray G. Here, θg is greater than θr.

[0033] As described above, in the optical device 20 according to this embodiment, a light ray emitted from an arbitrary object point O is imaged as a light ray of a color according to the angle the light ray makes with the optical axis when it enters the first lens 311. That is, in the optical device 20 according to this embodiment, the light ray emitted from an arbitrary object point O is color-separated into blue, red, and green light rays in ascending order of the angle the light ray makes with the optical axis. Here, if the angle between the light ray and the optical axis is θ, then when 0≦θ<θr, the light ray emitted from the arbitrary object point O is color-separated as a blue light ray. When θr≦θ<θg, the light ray emitted from the arbitrary object point O is color-separated as a red light ray. When θg≦θ, the light ray emitted from the arbitrary object point O is color-separated as a green light ray.

[0034] Furthermore, in the optical device 20 according to this embodiment, among the light rays emitted from an arbitrary object point O, when the light rays B enter the first lens 311, the chief ray of which is parallel to the optical axis, is separated as a blue light ray. In other words, the optical device 20 according to this embodiment can be described as a telecentric optical system that has telecentricity with respect to the blue light ray. On the other hand, the optical device 20 according to this embodiment can be described as a non-telecentric optical system that does not have telecentricity with respect to the red light ray R and the green light ray G.

[0035] Here, the operation of the processing circuit 70 will be described with reference to the drawings. Fig. 6 is a flowchart showing an example of calculation processing according to this embodiment. In the calculation processing, the processing circuit 70 according to this embodiment calculates information related to the test object based on the output of the image sensor 60.

[0036] In step S11, the processing circuit 70 serving as the color extraction unit 71 acquires the intensity of each of the R, G, and B rays of light that are emitted from an arbitrary object point O and incident on the imaging surface 61, based on the output of the imaging element 60. This separates the image data into colors.

[0037] In step S12, the processing circuit 70 functioning as the color extraction unit 71 identifies the color of the light ray that is emitted from an arbitrary object point O and incident on the imaging surface 61.

[0038] In step S13, the processing circuit 70 functioning as the scattering angle calculation unit 72 calculates the scattering angle of ambient light at the object point O based on the color of the identified light ray. In the optical device 20 according to this embodiment, the wavelength selection regions of the first color filter 313 are arranged concentrically. That is, in the optical device 20 according to this embodiment, the wavelength selection regions of the first color filter 313 are rotationally symmetric about the optical axis of the first lens 311. Therefore, the light ray is color-separated according to the scattering angle at an arbitrary object point O. When the color of the identified light ray is blue, the processing circuit 70 functioning as the scattering angle calculation unit 72 calculates that the scattering angle at the object point O is 0≦θ<θr. When the color of the identified light ray is red, the processing circuit 70 functioning as the scattering angle calculation unit 72 calculates that the scattering angle at the object point O is θr≦θ<θg. The processing circuit 70 functioning as the scattering angle calculation unit 72 calculates that when the color of the identified light ray is green, the scattering angle at the object point O is θg≦θ.

[0039] In this way, the optical inspection device 10 according to this embodiment can determine the scattering angle at the object point O based on the color of the captured light beam. That is, there is an advantage that the scattering angle at the object point O can be determined by color.

[0040] In the present embodiment, a case has been described as an example in which information related to the test object including the object point O is calculated based on ambient light scattered by the object point O, but the present invention is not limited to this. For example, the optical inspection device 10 may further include a light source. In this case, information related to whether or not a medium capable of refracting or scattering the light emitted from the light source exists between the light source and the first lens 311, and information related to the degree of refraction or scattering by the medium, can be obtained. For example, the optical inspection device 10 may be configured to include a transparent dot pattern or the like instead of a light source, so that the position of the object point O on the test surface can be identified. This identification can be achieved by image processing such as pixel matching and edge detection.

[0041] As described above, the technique according to this embodiment makes it possible to measure the scattering characteristics of the surface of a test object or the refractive index distribution in three-dimensional space with high accuracy.

[0042] (Second embodiment) The optical inspection system 1 according to this embodiment will be described in detail below with reference to the drawings. Here, differences from the first embodiment will be mainly described, and the same parts will be assigned the same reference numerals and descriptions thereof will be omitted.

[0043] In this embodiment, the wavelength of the red light is an example of a first wavelength, and the wavelength of the blue light is an example of a second wavelength.

[0044] First, the configuration of an optical inspection system 1 according to this embodiment will be described.

[0045] FIG. 7 is a block diagram showing an example of the configuration of a processing circuit 70 according to this embodiment. The processing circuit 70 functions as a color extraction unit 71, an image plane position acquisition unit 73, and an object point position calculation unit 74. The color extraction unit 71 acquires the intensity of each RGB of light rays reaching the imaging plane based on the output of the image sensor 60. The color extraction unit 71 is an example of a generation unit. The color extraction unit 71 separates the image data output by the image sensor 60 into color-specific image data. The image plane position acquisition unit 73 and the object point position calculation unit 74 are examples of a calculation unit. The calculation unit calculates information related to the test object including the object point O based on the image data for each color. Specifically, the image plane position acquisition unit 73 acquires the incident position of each RGB light ray on the imaging plane 61 based on the output of the color extraction unit 71. The image plane position acquisition unit 73 identifies the imaging position of the light ray emitted from the object point O in each of the image data for each color. The object point position calculation unit 74 calculates the three-dimensional position of the object point O of the test object based on the imaging positions of the light rays on the imaging plane 61. That is, the object point position calculation unit 74 calculates the three-dimensional position of the object point O as information related to the test object based on a plurality of imaging positions. The three-dimensional position of the object point O of the test object is an example of information related to the test object. The three-dimensional position of the object point O may be expressed as the three-dimensional position of a point on the object that is the test object.

[0046] Fig. 8 is an xz cross-sectional view showing an example of the configuration of the optical device 20 according to this embodiment. Fig. 8 also shows a schematic example of the ray path of the chief ray of light emitted from the object point O. As shown in Fig. 8, the optical system 30 according to this embodiment includes a first lens 321, a second color filter 325, and a first color filter 323.

[0047] In this embodiment, the z-axis is the optical axis of the first lens 321. The +z direction is the direction from the first lens 321 toward the imaging surface 61 of the imaging element 60. The x-axis and y-axis are perpendicular to each other and perpendicular to the z-axis. The -x direction is, for example, the direction of gravity. Here, for example, in the xz cross-sectional view of the optical device 20 shown in FIG. 8, the +z direction is the direction from left to right, the -x direction is the direction from top to bottom, and the +y direction is the direction from back to front perpendicular to the plane of the page.

[0048] The first lens 321 forms an image of light rays emitted from an object point O on the test object onto an image point on the imaging plane 61 of the imaging element 60. The first lens 321 is an example of a shared lens. The image-side focal length f of the first lens 321 is a focal length f2. The first lens 321 corresponds to the first lens 311 according to the first embodiment. The optical path length L between the image-side principal point of the first lens 321 and the imaging plane 61 is an optical path length L2. However, the first lens 321 may be the same lens as the first lens 311, or may be a different lens.

[0049] As shown in Fig. 8, the second color filter 325 is disposed adjacent to the first lens 321. The second color filter 325 is disposed on the +z side of the first lens 321. Fig. 9 is a schematic diagram showing an example of an xy cross section of the opening of the second color filter 325 according to this embodiment. As shown in Fig. 9, the wavelength selection member provided in the opening of the second color filter 325 has two concentric wavelength selection regions, a first region A1 and a second region A2.

[0050] The first region A1 is a region from radius r1 to radius r0. A red transmission filter that transmits red light is provided in the first region A1. The red transmission filter of the second color filter 325 is an example of a fourth wavelength selection filter. In other words, the first region A1 of the second color filter 325 is a region that transmits red light.

[0051] The second region A2 is a region with a radius equal to or smaller than r1. A blue transmission filter that transmits blue light is provided in the second region A2. The blue transmission filter of the second color filter 325 is an example of a fifth wavelength selection filter. In other words, the second region A2 of the second color filter 325 is a region that transmits blue light. The second region A2 is disposed on the optical axis of the first lens 321.

[0052] The second color filter 325 may be disposed on the −z side of the first lens 321.

[0053] 8, the first color filter 323 is disposed at the image-side focal point of the first lens 321. In other words, the first color filter 323 is disposed at a position separated by a focal length f2 on the +z side of the first lens 321. The first color filter 323 may also be expressed as being disposed at a position separated by a focal length f2 on the +z side of the second color filter 325. The aperture of the first color filter 323 may also be expressed as being located on the image-side focal plane of the first lens 321. The first color filter 323 is disposed at a position corresponding to the first color filter 313 according to the first embodiment.

[0054] 10 is a schematic diagram showing an example of an xy cross section of the opening of the first color filter 323 according to this embodiment. As shown in Fig. 10, the wavelength selection member provided in the opening of the first color filter 323 has two concentric wavelength selection regions, a first region A1 and a second region A2.

[0055] The first region A1 is a region from radius r1 to radius r0. A blue transmission filter that transmits blue light is provided in the first region A1. The blue transmission filter of the first color filter 323 is an example of a second wavelength selection filter. In other words, the first region A1 of the first color filter 323 is a region that transmits blue light.

[0056] The second region A2 is a region with a radius equal to or smaller than r1. A red transmission filter that transmits red light is provided in the second region A2. The red transmission filter of the first color filter 323 is an example of a first wavelength selection filter. In other words, the second region A2 of the first color filter 323 is a region that transmits red light. The second region A2 is disposed on the optical axis of the first lens 321.

[0057] In this way, the first wavelength-selective filter and the second wavelength-selective filter are integrally configured as the first color filter 323. In this case, each wavelength-selective filter is disposed rotationally symmetrically with respect to the optical axis of the first lens 321. Furthermore, the first wavelength-selective filter is disposed on the ray path of a light ray whose chief ray passes through the image-side focal point of the first lens 321.

[0058] Next, the operation of the optical inspection system 1 according to this embodiment will be described.

[0059] Light rays including light rays B and R are emitted from an arbitrary object point O on the test surface. These light rays are light rays such as ambient light reflected or scattered at the object point O. Of the light rays emitted from the arbitrary object point O, those that pass through the second color filter 325 and the first color filter 323 via the first lens 321 are incident on the imaging surface 61 of the imaging element 60.

[0060] First, consider light rays that were parallel to the optical axis of the first lens 321 when they entered the first lens 321. These light rays are incident on the second region A2 of the first color filter 323, which is disposed at the image-side focal point of the first lens 321. As shown in FIG. 8, of these light rays, the red light ray R that passed through the first region A1 of the second color filter 325 via the first lens 321 can pass through the second region A2 of the first color filter 323. On the other hand, the blue light ray that passed through the second region A2 of the second color filter 325 via the first lens 321 does not contain a red component and therefore cannot pass through the second region A2 of the first color filter 323.

[0061] Next, consider light rays that are not parallel to the optical axis of the first lens 321 when they enter the first lens 321. These light rays enter the first region A1 of the first color filter 323, which is located at the image-side focal point of the first lens 321, or a region outside the first region A1 of the first color filter 323. In other words, these light rays do not enter the second region A2 of the first color filter 323. Of these light rays, the red light ray that passes through the first region A1 of the second color filter 325 via the first lens 321 cannot pass through the first region A1 of the first color filter 323 because it does not contain a blue component. On the other hand, as shown in FIG. 8, the blue light ray B that passes through the second region A2 of the second color filter 325 via the first lens 321 can pass through the first region A1 of the first color filter 323.

[0062] As described above, the optical system 30 according to this embodiment is a telecentric optical system that has telecentricity on the object side for red light rays. On the other hand, the optical system 30 according to this embodiment is a non-telecentric optical system that does not have telecentricity on the object side for blue light rays. In the optical system 30 according to this embodiment, the optical axis of the telecentric optical system and the optical axis of the non-telecentric optical system coincide with each other.

[0063] The image sensor 60 simultaneously captures, among the light rays emitted from an arbitrary object point O, a red light ray R that has passed through the optical system 30 as a telecentric optical system and a blue light ray B that has passed through the optical system 30 as a non-telecentric optical system. The image sensor 60 outputs the imaging data obtained by imaging to the processing circuit 70. A non-telecentric optical system may also be referred to as a normal lens optical system.

[0064] Here, the operation of the processing circuit 70 will be described. The processing circuit 70 according to this embodiment calculates the three-dimensional shape of the object to be measured based on the output of the image sensor 60. In the measurement process, a calculation process is executed to calculate the three-dimensional position of the object point O. The calculation process includes the following color extraction process, image plane position acquisition process, and object point position calculation process. FIG. 11 is a flowchart showing an example of the calculation process according to this embodiment.

[0065] In step S21, the processing circuit 70 executes color extraction processing. The processing circuit 70, functioning as the color extraction unit 71, separates the captured image data into colors and extracts image data for each color. Note that although the term "image data" is used, it is not limited to data that can be displayed as an image, as long as the light intensity for each pixel of each color on the image sensor 60 is extracted.

[0066] In step S22, the processing circuit 70 executes an image plane position acquisition process. The processing circuit 70, functioning as the image plane position acquisition unit 73, identifies the imaging position of the light ray for each color based on the image data of each color. The imaging position at which the light ray is imaged can also be expressed as the incident position of the light ray on the imaging plane 61. The processing circuit 70, functioning as the image plane position acquisition unit 73, performs image processing such as edge enhancement on the image data, for example, to identify the imaging position corresponding to the object point O. At this time, image processing such as pixel matching can be performed on the shape of the detected edge, for example.

[0067] If a point light source is used as the object point O, for example, a position with a high luminance value in the image data may be identified as the imaging position. If a transparent dot pattern or the like is used as the object point O, for example, image processing such as the above-mentioned edge detection and pixel matching may be performed.

[0068] In step S23, the processing circuit 70 executes an object point position calculation process. The processing circuit 70, functioning as the object point position calculation unit 74, calculates the three-dimensional position of the object point O on the test object based on the imaging positions of the light rays of each color on the imaging plane 61.

[0069] Here, the object point position calculation process will be described in more detail.

[0070] The coordinates indicating the position of object point O in three-dimensional space are (x, y, z). The coordinates indicating the incident position on imaging plane 61 of red light ray R, which is emitted from object point O and passes through optical system 30 as a telecentric optical system, are (p, q). Furthermore, the coordinates indicating the incident position on imaging plane 61 of blue light ray B, which is emitted from object point O and passes through optical system 30 as a non-telecentric optical system, are (P, Q). The incident position on imaging plane 61 is the imaging position of the light ray.

[0071] The radius of the central region of the second color filter 325 is defined as radius r0. In other words, radius r0 is the radius r1 of the second region A2 of the second color filter 325. Here, the second region A2 of the second color filter 325 is the region through which blue light B passes. Also, the radius of the central region of the first color filter 323 is defined as radius r1. In other words, radius r1 is the radius r1 of the second region A2 of the first color filter 323. Here, the second region A2 of the first color filter 323 is the region through which red light R passes.

[0072] At this time, due to geometrical optics, the imaging position of the blue light ray B that has passed through the optical system 30 as a non-telecentric optical system is as follows:

number

[0073] On the other hand, due to geometrical optics, the imaging position of the red light ray R that has passed through the optical system 30 as a telecentric optical system is as follows:

number

[0074] From equations (1) and (2), the position of the object point O in three-dimensional space can be calculated using the imaging positions of each ray as follows:

number

[0075] The processing circuit 70 according to this embodiment can calculate the three-dimensional position of the object point O from the imaging data using equation (3). Furthermore, in the image plane position acquisition process, a plurality of imaging positions corresponding to a plurality of object points O on the test object are acquired for each color. Therefore, the processing circuit 70 according to this embodiment has the effect of being able to calculate the three-dimensional shape of the test object from the imaging data.

[0076] Here, a field measurement evaluation related to the optical inspection system 1 according to this embodiment will be described. FIG. 12 is a diagram for explaining an object point O in the field measurement evaluation according to this embodiment. In the field measurement evaluation, an aperture 301 shown in FIG. 12 was placed on an xy plane including the object point O in FIG. 8. An aperture 301a is provided in the aperture 301. In the field measurement evaluation, light rays passing through the aperture 301a of the aperture 301 were captured. That is, the object point O in this field measurement evaluation is an arbitrary position inside the aperture 301a. As shown in FIG. 12, the aperture 301a is an annular region centered on the optical axis. In addition, regions hatched with solid diagonal lines in the drawing are regions that do not transmit visible light. Note that, although the field measurement evaluation using the aperture 301a has been described in this embodiment, similar effects can be obtained when a ring-shaped illumination is used. The ring-shaped illumination is, for example, a plurality of light-emitting diodes (LEDs) arranged in a ring shape.

[0077] FIG. 13A shows an image acquired by the image sensor 60 in a measurement evaluation in which the aperture 301 was positioned 160 mm away from the first lens 321 on the -z side. FIG. 13B shows an image acquired by the image sensor 60 in a measurement evaluation in which the aperture 301 was positioned 210 mm away from the first lens 321 on the -z side. FIG. 13C shows an image acquired by the image sensor 60 in a measurement evaluation in which the aperture 301 was positioned 225 mm away from the first lens 321 on the -z side. In FIGS. 13A, 13B, and 13C, areas hatched with solid diagonal lines are areas in which light rays that passed through the optical system 30 were not captured. The annular areas hatched with dots are areas in which blue light rays were captured. The annular areas hatched with a grid pattern are areas in which red light rays were captured.

[0078] Fig. 14 is a graph showing the results of the actual measurement evaluation according to this embodiment. In the graph shown in Fig. 14, the horizontal axis represents the actual distance between the first lens 321 and the aperture 301 when the actual measurement evaluation was performed, and the vertical axis represents the distance between the first lens 321 and the aperture 301 calculated based on image data by the calculation process according to this embodiment. Plots 610, 620, and 630 are distances obtained from the images of Figs. 13A, 13B, and 13C, respectively. As shown in Fig. 14, it can be seen that the actual distance of the aperture 301 and the distance calculated based on image data are approximately the same value.

[0079] As described above, the optical inspection system 1 according to this embodiment can measure the three-dimensional position of the object point O with high accuracy. The three-dimensional position of the object point O is an example of information related to the test object. In other words, the technology according to this embodiment can measure the three-dimensional surface shape of the test object with high accuracy.

[0080] (Third embodiment) The optical inspection system 1 according to this embodiment will be described in detail below with reference to the drawings. Here, differences from the second embodiment will be mainly described, and the same parts will be assigned the same reference numerals and descriptions thereof will be omitted.

[0081] In this embodiment, the wavelength of the red light is an example of a first wavelength, and the wavelength of the blue light is an example of a second wavelength.

[0082] First, the configuration of an optical inspection system 1 according to this embodiment will be described.

[0083] Fig. 15 is an xz cross-sectional view showing an example of the configuration of the optical device 20 according to this embodiment. Fig. 15 also shows a schematic example of the ray path of the chief ray of light emitted from the object point O. As shown in Fig. 15, the optical system 30 according to this embodiment includes a first lens 331, a second color filter 335, and a first color filter 333.

[0084] In this embodiment, the z-axis is the optical axis of the first lens 331. The +z direction is the direction from the first lens 331 toward the imaging surface 61 of the imaging element 60. The x-axis and y-axis are perpendicular to each other and perpendicular to the z-axis. The -x direction is, for example, the direction of gravity. Here, for example, in the xz cross-sectional view of the optical device 20 shown in FIG. 8, the +z direction is the direction from left to right, the -x direction is the direction from top to bottom, and the +y direction is the direction from back to front perpendicular to the plane of the page.

[0085] The first lens 331 focuses light rays emitted from an object point O on the test object onto an image point on the imaging plane 61 of the imaging element 60. The first lens 331 is an example of a shared lens. The first lens 331 is also an example of a pair of lenses. The image-side focal length f of the first lens 331 is focal length f3. The first lens 331 has an object-side lens and an image-side lens. The object-side lens and the image-side lens have the same optical axis. The object-side lens and the image-side lens are symmetrical in the optical axis direction of the first lens 331. The object-side lens of the first lens 331 corresponds to the first lens 321 according to the second embodiment. The optical path length L between the image-side principal point of the first lens 331 and the imaging plane 61 is optical path length L3.

[0086] The second color filter 335 corresponds to the second color filter 325 according to the second embodiment. That is, the red transmission filter of the second color filter 335 is an example of a fourth wavelength-selective filter. The blue transmission filter of the second color filter 335 is an example of a fifth wavelength-selective filter. As shown in FIG. 15 , the second color filter 335 is disposed between the object-side lens and the image-side lens of the first lens 331.

[0087] The first color filter 333 corresponds to the first color filter 323 according to the second embodiment. In other words, the red transmission filter of the first color filter 333 is an example of a first wavelength-selective filter. The blue transmission filter of the first color filter 333 is an example of a second wavelength-selective filter. As shown in FIG. 15 , the first color filter 333 is disposed at the image-side focal point of the first lens 331. In other words, the first color filter 333 is disposed at a position spaced apart by a focal length f3 on the +z side of the first lens 331. Alternatively, the first color filter 333 may be expressed as being disposed at a position spaced apart by a focal length f3 on the +z side of the second color filter 335. The aperture of the first color filter 333 may also be expressed as being located on the image-side focal plane of the first lens 331.

[0088] In this way, the optical device 20 according to this embodiment can also be expressed as the optical device 20 according to the second embodiment to which an image-side lens of the first lens 331 is added.

[0089] The operation of the optical inspection system 1 according to this embodiment is similar to the operation of the optical inspection system 1 according to the second embodiment.

[0090] According to this configuration, the center of the second color filter 335 and the center of the first lens 331 can be aligned in the z-axis direction. Therefore, according to the optical inspection system 1 according to this embodiment, in addition to the effects obtained by the optical inspection system 1 according to the second embodiment, an effect of improving the measurement accuracy of the light ray B can be obtained.

[0091] (Fourth embodiment) The optical inspection system 1 according to this embodiment will be described in detail below with reference to the drawings. Here, differences from the first embodiment will be mainly described, and the same parts will be assigned the same reference numerals and descriptions thereof will be omitted.

[0092] In this embodiment, the wavelength of the red light is an example of a first wavelength, and the wavelength of the blue light is an example of a second wavelength.

[0093] First, the configuration of an optical inspection system 1 according to this embodiment will be described.

[0094] Fig. 16 is an xz cross-sectional view showing an example of the configuration of the optical device 20 according to this embodiment. Fig. 16 also shows a schematic example of the ray path of the chief ray of light emitted from the object point O. As shown in Fig. 16, the optical system 30 according to this embodiment includes an object-side half mirror 346a, an object-side mirror 347a, a first lens 341a, a first wavelength-selective filter 344a, an aperture stop 344c, an image-side mirror 347b, an image-side half mirror 346b, a second lens 341b, and a second wavelength-selective filter 344b.

[0095] In this embodiment, the z-axis is the optical axis of the second lens 341b. The +z direction is the direction from the second lens 341b toward the imaging surface 61 of the imaging element 60. The x-axis and y-axis are perpendicular to each other and perpendicular to the z-axis. The -x direction is, for example, the direction of gravity. Here, for example, in the xz cross-sectional view of the optical device 20 shown in FIG. 8, the +z direction is the direction from left to right, the -x direction is the direction from top to bottom, and the +y direction is the direction from back to front perpendicular to the plane of the page.

[0096] The optical system 30 according to this embodiment includes a telecentric optical system and a non-telecentric optical system. The telecentric optical system includes an object-side half mirror 346a, an object-side mirror 347a, a first lens 341a, a first wavelength-selective filter 344a, an aperture stop 344c, an image-side mirror 347b, and an image-side half mirror 346b. The non-telecentric optical system includes an object-side half mirror 346a, a second lens 341b, a second wavelength-selective filter 344b, and an image-side half mirror 346b.

[0097] 16, in the telecentric optical system, an object-side half mirror 346a, an object-side mirror 347a, a first lens 341a, a first wavelength-selective filter 344a, an aperture stop 344c, an image-side mirror 347b, and an image-side half mirror 346b are arranged in that order from the object side. On the other hand, in the non-telecentric optical system, an object-side half mirror 346a, a second lens 341b, a second wavelength-selective filter 344b, and an image-side half mirror 346b are arranged in that order from the object side.

[0098] The first lens 341a and the second lens 341b each focus a light beam emitted from an object point O onto an image point on the imaging plane 61 of the image sensor 60. The image-side focal length f of the first lens 341a is a focal length f4. The first lens 341a and the second lens 341b are disposed at a position that is an optical path length a from an arbitrary object point O on the surface to be measured. The second lens 341b is disposed at a position that is an optical path length b from an arbitrary image point on the imaging plane 61. The sum of the reciprocal of the optical path length a and the reciprocal of the optical path length b is equal to the reciprocal of the focal length f4. The first lens 341a and the second lens 341b correspond to the first lens 311 according to the first embodiment. The optical path length L between the image-side principal point of the first lens 341a and the imaging plane 61 is an optical path length L4.

[0099] 16, the object-side half mirror 346a and the image-side half mirror 346b are disposed on the optical axis of the second lens 341b. As shown in FIG. 16, the object-side half mirror 346a according to this embodiment splits a light ray emitted from an object point O into a light ray directed toward the second lens 341b and a light ray directed toward the object-side mirror 347a. As shown in FIG. 16, the image-side half mirror 346b according to this embodiment combines a light ray incident from the image-side mirror 347b with a light ray that has passed through the second wavelength-selective filter 344b, and emits the combined light in a direction toward the imaging plane 61.

[0100] 16, the object-side mirror 347a and the image-side mirror 347b are disposed on the optical axis of the first lens 341a. The object-side mirror 347a reflects light rays incident from the object-side half mirror 346a and causes them to enter the first lens 341a. The image-side mirror 347b reflects light rays that have passed through the aperture stop 344c and causes them to enter the image-side half mirror 346b.

[0101] As shown in FIG. 16, the first wavelength-selective filter 344a is disposed adjacent to the first lens 341a. FIG. 17 is a schematic diagram showing an example of an xy cross section of the opening of the first wavelength-selective filter 344a according to this embodiment. As shown in FIG. 17, the wavelength-selective member provided in the opening of the first wavelength-selective filter 344a has one wavelength-selective region, i.e., the first region A1. The first region A1 is a region with a radius of r0 or less, and is a region provided with a red transmission filter that transmits red light. The first region A1 is disposed on the optical axis of the first lens 341a.

[0102] The first wavelength selection filter 344a may be disposed at any position between the object-side half mirror 346a and the image-side half mirror 346b, which include the first lens 341a.

[0103] As shown in FIG. 16, the aperture stop 344c is disposed at the image-side focal point of the first lens 341a. In other words, the aperture stop 344c is disposed at a position separated by a focal length f4 on the +z side of the first lens 341a. The aperture of the aperture stop 344c can also be expressed as being located on the image-side focal plane of the first lens 341a. FIG. 18 is a schematic diagram showing an example of an xy cross section of the aperture of the aperture stop 344c according to this embodiment. As shown in FIG. 18, the wavelength-selecting member provided in the aperture of the aperture stop 344c has two concentric wavelength-selecting regions, a first region A1 and a second region A2. The first region A1 is a region from radius r1 to radius r0. The first region A1 does not transmit light of any wavelength in the visible light range. In other words, the color of the wavelength-selecting member constituting the first region A1 may be black. The second region A2 is a region having a radius equal to or less than r1. The second region A2 transmits light of any wavelength in the visible light range. That is, the color of the wavelength-selecting member constituting the second region A2 may be transparent. Note that the wavelength-selecting member does not necessarily have to be provided in the second region A2.

[0104] As shown in FIG. 16, the second wavelength-selective filter 344b is disposed adjacent to the second lens 341b. FIG. 19 is a schematic diagram showing an example of an xy cross section of the opening of the second wavelength-selective filter 344b according to this embodiment. As shown in FIG. 19, the wavelength-selective member provided in the opening of the second wavelength-selective filter 344b has one wavelength-selective region, i.e., the first region A1. The first region A1 is a region with a radius of r0 or less, and is a region provided with a blue transmission filter that transmits blue light. The first region A1 is disposed on the optical axis of the second lens 341b.

[0105] The first wavelength selection filter 344a, aperture stop 344c, and second wavelength selection filter 344b according to this embodiment correspond to the first color filter 313 according to the first embodiment, the first color filter 323 according to the second embodiment, or the first color filter 333 according to the third embodiment.

[0106] As described above, in the optical system 30 according to this embodiment, the optical axis of the telecentric optical system 40, which is the optical axis of the first lens 341a, and the optical axis of the non-telecentric optical system 50, which is the optical axis of the second lens 341b, are not coaxial.

[0107] Next, the operation of the optical inspection system 1 according to this embodiment will be described.

[0108] Light rays including light rays B and R are emitted from an arbitrary object point O on the test surface. These light rays are light rays such as ambient light reflected or scattered at the object point O. A portion of the light rays emitted from the arbitrary object point O enters the first lens 341a via the object-side half mirror 346a and the object-side mirror 347a, and another portion enters the second lens 341b via the object-side half mirror 346a.

[0109] Of the light rays that pass through the first lens 341a, red light ray R can pass through the first wavelength-selective filter 344a. Of the light rays that pass through the first wavelength-selective filter 344a, red light ray R that was parallel to the optical axis of the first lens 341a when incident on the first lens 341a can pass through the second region A2 of the aperture stop 344c that is disposed at the image-side focus of the first lens 341a. On the other hand, light rays that were not parallel to the optical axis of the first lens 341a when incident on the first lens 341a cannot pass through the aperture stop 344c. The red light ray R that passed through the aperture stop 344c is incident on the image-side half mirror 346b via the image-side mirror 347b.

[0110] Of the light rays that have passed through the second lens 341b, the blue light ray B can pass through the second wavelength selection filter 344b. The blue light ray B that has passed through the second wavelength selection filter 344b is incident on the image-side half mirror 346b.

[0111] At the image-side half mirror 346b, the optical axis of the red light ray R that has passed through the telecentric optical system coincides with the optical axis of the blue light ray B that has passed through the non-telecentric optical system.

[0112] The operations of the image sensor 60 and the processing circuit 70 according to this embodiment are similar to the operations of the image sensor 60 and the processing circuit 70 according to the second and third embodiments, respectively.

[0113] Thus, in the optical system 30 according to this embodiment, of the light rays emitted from the object point O, those that pass through a telecentric optical system are imaged as red light rays R. On the other hand, of the light rays emitted from the object point O, those that pass through a non-telecentric optical system are imaged as blue light rays B. In other words, the optical system 30 according to this embodiment is telecentric with respect to red light rays. Furthermore, in the optical inspection device 10 according to this embodiment, light rays emitted from the same object point O are imaged as light rays of different colors depending on the optical system through which they pass.

[0114] The optical inspection system 1 according to this embodiment has the following advantages in addition to the advantages of the optical inspection system 1 according to the second embodiment. In the optical inspection system 1 according to this embodiment, the telecentric optical system 40 and the non-telecentric optical system 50 are not coaxial, so they can be adjusted independently. Furthermore, folding the ray path can improve the degree of freedom in designing the optical device 20. Note that the object-side mirror 347a and the image-side mirror 347b may be included in the non-telecentric optical system 50.

[0115] It should be noted that the technology according to the third embodiment can be applied to the optical inspection system 1 according to this embodiment. In this case, in addition to the effects described above, the effects obtained in the third embodiment can be further obtained.

[0116] The first wavelength-selective filter 344a and the aperture stop 344c may be integrally configured. FIG. 20 is a schematic diagram illustrating an example of an xy cross section of the aperture of a first wavelength-selective filter 344d according to a modified example of this embodiment. The first wavelength-selective filter 344d according to the modified example is an integrally configured first wavelength-selective filter 344a and aperture stop 344c. Like the aperture stop 344c, the first wavelength-selective filter 344d according to the modified example may be disposed at the image-side focal point of the first lens 341a. As shown in FIG. 20, the wavelength-selective member provided in the aperture of the first wavelength-selective filter 344d according to the modified example has two concentric wavelength-selective regions, a first region A1 and a second region A2. The first region A1 is a region from radius r1 to radius r0. The first region A1 does not transmit light of any wavelength in the visible light range. In other words, the color of the wavelength-selective member constituting the first region A1 is black. The second region A2 is a region with a radius equal to or smaller than r1. The second region A2 is a region in which a red transmission filter that transmits red light is provided. The second region A2 is disposed on the optical axis of the second lens 341b. In other words, the first wavelength-selective filter 344d according to the modified example is disposed on the aperture plane of the aperture stop 344c, and it can be said that the first wavelength-selective filter 344a and the aperture stop 344c are integrally configured. This configuration provides the same effects as those described above, as well as the effects of reducing the number of parts and the amount of wavelength-selective members used, and of making the optical system 30 smaller and less expensive.

[0117] The first lens 341a and the second lens 341b may be integrally configured. In this case, in the optical system 30 according to this embodiment, the telecentric optical system 40 and the non-telecentric optical system 50 can be said to share at least one lens. In other words, the integrally configured first lens 341a and second lens 341b are an example of a shared lens. The integrally configured first lens 341a and second lens 341b may be disposed between the object point O and the object-side half mirror 346a. The aperture stop 344c may be disposed at the image-side focal point of the integrally configured first lens 341a and second lens 341b via the object-side half mirror 346a and the object-side mirror 347a. This configuration provides the same effects as those described above, as well as the effects of reducing the number of parts and achieving a smaller and more cost-effective optical system 30.

[0118] The first wavelength-selective filter 344a and the aperture stop 344c may be integrally configured, and the first lens 341a and the second lens 341b may be integrally configured. Even with this configuration, the same effects as those described above can be obtained.

[0119] (Fifth embodiment) In the first, second, third, and fourth embodiments, the optical device 20 has been described as being telecentric on the object side, but this is not limiting. The optical device 20 according to each embodiment only needs to be telecentric on at least the object side, and may also be telecentric on the image side. In an image-side telecentric optical system, the exit pupil is located at infinity, and the optical axis and the chief ray are parallel in image space. In other words, the optical system 30 according to each embodiment may be a double-telecentric optical system for light rays of any wavelength.

[0120] Here, an example will be described in which the optical system 30 according to the second embodiment is further telecentric on the image side. Differences from the second embodiment will be mainly described, and the same parts will be denoted by the same reference numerals and their description will be omitted.

[0121] In this embodiment, the wavelength of the red light is an example of a first wavelength, and the wavelength of the blue light is an example of a second wavelength.

[0122] First, the configuration of an optical inspection system 1 according to this embodiment will be described.

[0123] Fig. 21 is an xz cross-sectional view showing an example of the configuration of the optical device 20 according to this embodiment. Fig. 21 also shows a schematic example of a light path of a chief ray of light emitted from an object point O. As shown in Fig. 21, the optical system 30 according to this embodiment includes the optical system 30 according to the second embodiment and a third lens 352.

[0124] The third lens 352 forms an image of light rays that have passed through the first color filter 323 on the imaging surface 61. The third lens 352 is, for example, the same as the first lens 321 according to the second embodiment. The third lens 352 is disposed between the first color filter 323 and the imaging surface 61. The first color filter 323 is disposed at the object-side focal point of the third lens 352. The object-side focal length of the third lens 352 is a focal length f5. In other words, the third lens 352 is disposed on the +z side from the first color filter 323 by the focal length f5. The optical axis of the third lens 352 is coaxial with the optical axis of the first lens 321.

[0125] Next, the operation of the optical inspection system 1 according to this embodiment will be described.

[0126] The red light ray R that passes through the second region A2 of the first color filter 323 is emitted from the third lens 352 as a light ray parallel to the optical axis of the third lens 352. On the other hand, the blue light ray B that passes through the first region A1 of the first color filter 323 is emitted from the third lens 352 as a light ray that is not parallel to the optical axis of the third lens 352.

[0127] As described above, the optical system 30 according to this embodiment is a double telecentric optical system that is telecentric on both the object side and the image side with respect to the red light ray R. Moreover, the optical system 30 according to this embodiment is a normal optical system that is not telecentric on either the object side or the image side with respect to the blue light ray B. In addition to the above-described effects, this configuration also provides the effect of improving the degree of freedom in designing the optical device 20, such as the arrangement of the image sensor 60.

[0128] It should be noted that the radii r2, r1, and r0 according to the above-described embodiments are values ​​that can be set appropriately depending on the size and arrangement of each optical element included in the optical system 30 according to the embodiment.

[0129] Note that, in the optical inspection systems 1 according to the second, third, fourth, and fifth embodiments, three or more wavelength selection regions may be provided, similar to the first color filter 313 according to the first embodiment. In this case, for example, in an optical system that is telecentric on the object side with respect to a red light ray, the three-dimensional position of the object point O can be calculated based on the imaging position of the red light ray and the imaging position of the blue light ray or the imaging position of the green light ray. With this configuration, the accuracy of the calculation process can be improved.

[0130] The techniques according to the above-described embodiments can realize the following optical inspection method. The optical inspection method according to the above-described embodiments includes acquiring image data by capturing images of light rays emitted from an object point O that have passed through an optical system 30. The optical system 30 includes a telecentric optical system 40 and a non-telecentric optical system 50. The telecentric optical system 40 is telecentric on the object side with respect to light rays of a first wavelength. The non-telecentric optical system is not telecentric with respect to light rays of a second wavelength. Note that the first wavelength and the second wavelength are different. The light rays emitted from the object point O include a first wavelength and a second wavelength. In this case, the optical inspection method according to the above-described embodiments acquires image data by simultaneously capturing images of light rays of the first wavelength that have passed through the telecentric optical system 40 and light rays of the second wavelength that have passed through the non-telecentric optical system 50, among the light rays emitted from the object point O. The optical inspection method according to the above-described embodiments further includes color-separating the acquired image data to generate image data for each color. The optical inspection method according to each of the above-described embodiments further includes calculating information related to the test object including the object point O based on the image data for each color.

[0131] Although several 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 embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0132] 1...optical inspection system, 10...optical inspection device, 20...optical device, 30...optical system, 40...telecentric optical system, 50...non-telecentric optical system, 60...imaging element, 61...imaging surface, 70...processing circuit, 71...color extraction unit (generation unit), 72...scattering angle calculation unit (calculation unit), 73...image plane position acquisition unit (calculation unit), 74...object point position calculation unit (calculation unit), 80...memory, 90...display, 301...aperture, 311...first lens, 313...first color filter, 321...first lens, 323...first Color filter, 325...second color filter, 331...first lens, 333...first color filter, 335...second color filter, 341a...first lens, 341b...second lens, 344a...first wavelength selective filter, 344b...second wavelength selective filter, 344c...aperture stop, 344d...first wavelength selective filter, 346a...object-side half mirror, 346b...image-side half mirror, 347a...object-side mirror, 347b...image-side mirror, 352...third lens.

Claims

1. a first optical system having a first wavelength selection filter that passes a light beam of a first wavelength and having telecentricity on an object side with respect to the light beam of the first wavelength; a second optical system having a second wavelength selection filter that passes light rays of a second wavelength different from the first wavelength, the first wavelength selection filter and the second wavelength selection filter being disposed in a common filter, and having non-telecentricity on the object side with respect to light rays of the second wavelength; an image sensor capable of capturing an image of the object based on a light ray of the first wavelength that has passed from an object point of the object through the first optical system and a light ray of the second wavelength that has passed from the object point through the second optical system; a processing circuit that separates image data from the image sensor into color data for each color, and measures the surface condition of the object based on scattering information composed of at least the light beam of the first wavelength and the light beam of the second wavelength at the object point from the image data for each color; Equipped with the first optical system and the second optical system share a lens that is disposed on the object side with respect to the first wavelength-selective filter and the second wavelength-selective filter, the first wavelength-selective filter passes a light beam of the first wavelength that is incident on the lens parallel to an optical axis of the lens; the second wavelength-selective filter passes the light beam of the second wavelength that is incident on the lens at a larger inclination with respect to the optical axis of the lens than the light beam of the first wavelength, and is disposed outside the first wavelength-selective filter with respect to the optical axis of the lens. Optical inspection equipment.

2. 2. The optical inspection device according to claim 1, wherein the optical axis of the first optical system and the optical axis of the second optical system are coaxial.

3. The optical inspection device of claim 2 , wherein the common filter is a first color filter.

4. The optical inspection device of claim 3 , wherein the first color filter is disposed on a focal plane of the lens.

5. In the first color filter, the first wavelength-selective filter and the second wavelength-selective filter are arranged rotationally symmetrically with respect to the optical axis of the lens, the first wavelength-selective filter is disposed on a ray path of a ray whose chief ray passes through the focal point of the lens; The optical inspection device according to claim 4 .

6. the second optical system further includes a third wavelength selection filter that passes light rays having a third wavelength different from the first wavelength and the second wavelength; the third wavelength-selective filter, together with the first wavelength-selective filter and the second wavelength-selective filter, is disposed on the first color filter in rotational symmetry with respect to the optical axis of the lens; the second wavelength-selective filter and the third wavelength-selective filter are arranged such that a light ray having the second wavelength is incident on the second wavelength-selective filter, and a light ray having the third wavelength and a scattering angle different from a scattering angle of the light ray having the second wavelength is incident on the third wavelength-selective filter, the imaging element is capable of further coaxially imaging the light beam of the third wavelength that has passed through the second optical system; The optical inspection device according to claim 5 .

7. The optical inspection device according to claim 1 , wherein the first optical system further has telecentricity on the image side.

8. The optical inspection device according to claim 1 , wherein the first wavelength-selective filter and the second wavelength-selective filter are arranged rotationally symmetrically with respect to the common filter.

9. acquiring image data by simultaneously capturing an image of a light ray having a first wavelength that has passed from an object point on an object through a first optical system and a light ray having a second wavelength that is different from the first wavelength and that has passed from the object point through a second optical system; The image data is separated into colors to generate image data for each color; measuring a surface state of the object based on scattering information formed from at least the light beam of the first wavelength and the light beam of the second wavelength at the object point from the image data for each color; An optical inspection method, comprising: the first optical system has a first wavelength selection filter that passes the light beam of the first wavelength, and is telecentric on the object side with respect to the light beam of the first wavelength; the second optical system has a second wavelength-selective filter that passes the light beam of the second wavelength, the first wavelength-selective filter and the second wavelength-selective filter are disposed in a common filter, and the second optical system has non-telecentricity on the object side with respect to the light beam of the second wavelength; the first optical system and the second optical system share a lens that is disposed on the object side with respect to the first wavelength-selective filter and the second wavelength-selective filter, the first wavelength-selective filter passes a light beam of the first wavelength that is incident on the lens parallel to an optical axis of the lens; the second wavelength-selective filter passes the light beam of the second wavelength that is incident on the lens at a larger inclination with respect to the optical axis of the lens than the light beam of the first wavelength, and is disposed outside the first wavelength-selective filter with respect to the optical axis of the lens. Optical inspection methods.

10. On the computer, a function of simultaneously capturing an image of a light ray having a first wavelength that has passed from an object point on an object through a first optical system and a light ray having a second wavelength that is different from the first wavelength and that has passed from the object point through a second optical system, thereby acquiring image data; a function of separating the image data into colors to generate image data for each color; a function of measuring the surface condition of the object based on scattering information composed of at least the light beam of the first wavelength and the light beam of the second wavelength at the object point from the image data for each color; An optical inspection program that realizes the above. the first optical system has a first wavelength selection filter that passes the light beam of the first wavelength, and is telecentric on the object side with respect to the light beam of the first wavelength; the second optical system has a second wavelength-selective filter that passes the light beam of the second wavelength, the first wavelength-selective filter and the second wavelength-selective filter are disposed in a common filter, and the second optical system has non-telecentricity on the object side with respect to the light beam of the second wavelength; the first optical system and the second optical system share a lens that is disposed on the object side with respect to the first wavelength-selective filter and the second wavelength-selective filter, the first wavelength-selective filter passes a light beam of the first wavelength that is incident on the lens parallel to an optical axis of the lens; the second wavelength-selective filter passes the light beam of the second wavelength that is incident on the lens at a larger inclination with respect to the optical axis of the lens than the light beam of the first wavelength, and is disposed outside the first wavelength-selective filter with respect to the optical axis of the lens. Optical inspection program.

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