Optical inspection apparatus and optical inspection system

Abstract

The present invention provides an optical inspection device capable of acquiring multiple images corresponding to the direction of light rays from an object. [Solution] The optical inspection apparatus comprises an imaging optical element 22 having an imaging optical axis, an image sensor 24 having a light-receiving surface intersecting the imaging optical axis, and a movable first light-selective aperture 26. The first light-selective aperture 26 has a first light-selective region 32 and a second light-selective region 34 that selectively transmit light from an object in different directions. The first light-selective aperture 26 is positioned at or near the focal plane fs of the imaging optical element. When the first light-selective region of the first light-selective aperture is moved to a position that includes the imaging optical axis, the image sensor captures an image of the object incident on the light-receiving surface through the first light-selective region and acquires a first image. When the second light-selective region of the first light-selective aperture is moved to a position that includes the imaging optical axis, the image sensor captures an image of the object incident on the light-receiving surface through the second light-selective region and acquires a second image.

Description

Technical Field

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

Background Art

[0002] In various industries, non-contact inspection of objects has become important. In the conventional method, there is a technique of identifying the direction of a light beam by associating one-to-one the color (wavelength spectrum) of a light beam spectrally analyzed using a diffraction grating or a wavelength filter with the light beam direction, and acquiring information on the object surface or inside the object by specifying the color.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem that this invention aims to solve is to provide an optical inspection device capable of acquiring multiple images corresponding to the direction of light rays from an object, and an optical inspection system having the optical inspection device. [Means for solving the problem]

[0006] According to one embodiment, the optical inspection apparatus comprises an imaging optical element having an imaging optical axis, an image sensor having a light-receiving surface intersecting the imaging optical axis, and a movable first light-selective aperture. The first light-selective aperture has a first light-selective region and a second light-selective region that selectively transmit light from an object in different directions. The first light-selective aperture is positioned at or near the focal plane of the imaging optical element. When the first light-selective region of the first light-selective aperture is moved to a position that includes the imaging optical axis, the image sensor captures an image of the object incident on the light-receiving surface through the imaging optical element and the first light-selective region to acquire a first image. When the second light-selective region of the first light-selective aperture is moved to a position that includes the imaging optical axis, the image sensor captures an image of the object incident on the light-receiving surface through the imaging optical element and the second light-selective region to acquire a second image. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic diagram showing an optical inspection system according to the first embodiment. [Figure 2] This schematic diagram shows the optical inspection system shown in Figure 1 with the intersection of the first optically selective aperture and the optical axis moved to the second optically selective region. [Figure 3] A schematic block diagram of the optical inspection system according to the first embodiment. [Figure 4] A flowchart for performing optical inspection using the optical inspection system according to the first embodiment. [Figure 5] A schematic diagram corresponding to Figure 1, showing an optical inspection system according to Modification 1 of the First Embodiment. [Figure 6] A schematic diagram corresponding to Figure 2, showing an optical inspection system according to Modification 1 of the First Embodiment. [Figure 7] A schematic diagram showing the first optically selective aperture of an optical inspection system according to a modified example 2 of the first embodiment. [Figure 8] A schematic diagram showing the first light-selective aperture of an optical inspection system according to a modified example 3 of the first embodiment. [Figure 9] A schematic diagram showing the first and second optically selective apertures of the optical inspection apparatus of the optical inspection system according to the second embodiment. [Figure 10] A schematic cross-sectional view along the xz plane in Figure 9. [Figure 11] A schematic diagram showing the first and second optically selective apertures shown in Figure 9 rotated around their respective rotation axes. [Figure 12] A schematic diagram showing the first optically selective aperture shown in Figure 9 rotated around the axis of rotation of the first optically selective aperture. [Figure 13] A magnified view of the aperture edge of the first optically selective aperture in Figure 10. [Figure 14] A magnified view of the aperture edge of the first optically selective aperture in Figure 10. [Figure 15] A schematic block diagram of the optical inspection system according to the second embodiment. [Figure 16] A schematic diagram showing the first and second optically selective apertures of the optical inspection device of the optical inspection system according to a modified example of the second embodiment. [Figure 17] A schematic cross-sectional view along the xz plane in Figure 16. [Modes for carrying out the invention]

[0008] The embodiments of the present invention will be described below with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes of the parts, etc., are not necessarily the same as those of reality. Furthermore, even when representing the same part, the dimensions and ratios may be represented differently in the drawings. In this specification and each drawing, the same reference numerals are used for elements that are the same as those described above with respect to previously shown drawings, and detailed explanations are omitted as appropriate.

[0009] In this specification, light is a type of electromagnetic wave, including gamma rays, X-rays, ultraviolet rays, visible light, infrared rays, radio waves, etc. In this embodiment, light is assumed to be visible light, and for example, the wavelength is in the range of 400 nm to 750 nm.

[0010] (First Embodiment) Hereinafter, the optical inspection system 10 according to this embodiment will be described with reference to FIGS. 1 to 4. END]]

[0011] FIGS. 1 and 2 show schematic cross-sectional views of the optical inspection system 10 according to this embodiment. FIG. 3 is a schematic block diagram of the optical inspection system 10. FIGS. 1 and 2 are the same except for the position of the first light selection aperture 26 being different.

[0012] The optical inspection system 10 includes an optical inspection device 12 and a processing unit 14. In this embodiment, the optical inspection device 12 includes an imaging unit 20 that images light incident from the object O along the z-axis.

[0013] The imaging unit 20 includes an imaging optical element 22, an image sensor 24, and a first light selection aperture 26.

[0014] The imaging optical element 22 can image the light from the object О. The imaging optical element 22 may be, for example, a single lens, a combination lens composed of multiple lenses, a concave mirror, a Fresnel lens, a diffraction grating, a gradient index lens (GRIN lens), etc. That is, the imaging optical element 22 may be anything as long as it can image light. The surface on which the set of points at infinity is imaged by the imaging optical element 22 is defined as the focal plane fs. The focal plane fs and its vicinity are called the focal plane region. The optical axis C of the imaging optical element 22 is a straight line perpendicular to the focal plane fs. The light emitted from a point far enough on the optical axis C is assumed to be imaged at the point where the optical axis C intersects the focal plane fs. This point is called the focus.

[0015] The imaging optical element 22 has a geometrically defined principal surface 22a. The distance between the focal plane fs of the imaging optical element 22 and the principal surface 22a closest to it is defined as the focal length f of the imaging optical element.

[0016] It is assumed that the principal surface 22a and focal plane fs of the imaging optical element 22 are parallel to the xy-plane perpendicular to the z-axis. The y-axis is perpendicular to the x-axis.

[0017] In this embodiment, the imaging optical element 22 is assumed to be a lens assembly composed of multiple lenses. Here, this is referred to as the imaging lens. However, in Figure 1, for simplicity, the imaging lens 22, which is a lens assembly, is schematically depicted as a single lens. Furthermore, the imaging optical element 22 is not limited to this; any element that images light may be used. In the cross-sectional views (xz section) shown in Figures 1 and 2, the optical axis C of the imaging optical element 22 is assumed to be included in this section. In the cross-sectional views (xz section) shown in Figures 1 and 2, the optical axis C of the imaging optical element 22 is assumed to coincide with the z axis.

[0018] In particular, the imaging optical element 22 provided in the imaging unit 20 is sometimes called the imaging optical element. Also, the optical axis C of the imaging optical element 22 is called the imaging optical axis.

[0019] The image sensor 24 can be an area sensor of an appropriate type. The image sensor 24 has a light-receiving surface 24a that intersects with the imaging optical axis C of the imaging optical element 22, and acquires an image from the light incident on the light-receiving surface 24a.

[0020] The first optically selective aperture 26 is positioned at or near the focal plane fs of the imaging optical element 22. The first optically selective aperture 26 has two distinct first optically selective regions 32 and a second optically selective region 34, and an aperture movement mechanism 36.

[0021] The first light-selective region 32 either changes (modifies) the characteristics of the incident light and allows it to pass through, or it passes through without changing (modifying) them. Here, optical characteristics refer to the direction, wavelength, wavelength spectrum, polarization, brightness, illuminance, and luminous flux (amount of light) of the incident light ray. The second light-selective region 34 either changes (modifies) the characteristics of the incident light and allows it to pass through, or it passes through without changing (modifying) them. The first light-selective region 32 and the second light-selective region 34 may shield some of the light. That is, changing (modifying) the characteristics of the incident light and allowing it to pass through in the first light-selective region 32 and the second light-selective region 34 respectively includes shielding the incident light.

[0022] In this embodiment, the first light-selection region 32 and the second light-selection region 34 are formed, for example, as regions arranged in a row along the x-axis direction, each consisting of a region that blocks light and a region that allows light to pass through adjacent to one another.

[0023] In this embodiment, the relative positional relationship between the first optical selection region 32 and the second optical selection region 34 of the first optical selection aperture 26 does not change.

[0024] The aperture movement mechanism 36 can move the first optical selection region 32 and the second optical selection region 34, for example, along the focal plane fs, for example, in the x-axis direction. The aperture movement mechanism 36 uses a motor or the like as a drive source controlled by the processing unit 14, and in combination with a ball screw or the like, controls the position of the first optical selection region 32 and the position of the second optical selection region 34 intersecting the optical axis C of the imaging optical element 22. A stepping motor is preferred as the drive source, but a servo motor or a linear drive mechanism may also be used. In other words, any drive source that can change the position of the first optical selection region 32 and the position of the second optical selection region 34 is acceptable.

[0025] In this embodiment, an example is shown in which both the first optical selection region 32 and the second optical selection region 34 appear in the cross-sections shown in Figures 1 and 2. For example, when the first optical selection region 32 is visible in Figure 1, the first optical selection aperture 26 may be movably positioned so that the second optical selection region 34 does not appear on this cross-section. Similarly, when the second optical selection region 34 is visible on this cross-section in Figure 2, the first optical selection aperture 26 may be movably positioned so that the first optical selection region 32 does not appear on this cross-section.

[0026] Object O can be either light-transmitting or light-reflecting, or it can be semi-transparent. A point on the surface or inside object O is called an object point OP. In the following, unless otherwise specified, object O is assumed to be light-reflecting, and object point OP is assumed to be on the surface of object O. The surface of object O is sometimes called the object surface or object plane.

[0027] In this embodiment, the first light-selective region 32 has a light-shielding region 42 that blocks light and a light-passing region (through-hole) 44 that allows light to pass through. In the cross-section shown in Figure 1, the first light-selective region 32 is preferably symmetrical with respect to the optical axis C, but is not limited to this. The light-passing region 44 can be considered as a light-transmitting region that allows light to pass through. In this embodiment, the through-hole 44 is formed as the light-passing region.

[0028] The light-shielding regions 42 are arranged, for example, in groups of three spaced apart in the x-axis direction. The light-passing regions 44 are formed between the light-shielding regions 42. The relative positional relationship between the light-shielding regions 42 and the light-passing regions 44 is fixed.

[0029] In Figure 1, the optical axis C intersects the middle of the three aligned light-shielding regions 42. The middle light-shielding region 42 in Figure 1 is sometimes referred to as region 42a containing the first central axis C1. The first central axis C1 is a virtual axis located in the center of region 42a with respect to the x-axis direction and parallel to the z-axis direction.

[0030] When the light-shielding region 42a, which includes the first central axis C1 of the first light-selection region 32, is aligned with the imaging optical axis C of the imaging optical element 22, light rays B11 and B12 from the object O that form a first angle θ1 (not limited to one angle, and referring to an angle within an appropriate range) with respect to the optical axis C pass through the first light-selection region 32.

[0031] The second light-selective region 34 has a light-shielding region 52 that blocks light and a light-passing region (through-hole) 54 that allows light to pass through. In the cross-section shown in Figure 2, the second light-selective region 34 is preferably symmetrical with respect to the optical axis C, but is not limited to this. The light-passing region 54 can be considered as a light-transmitting region that allows light to pass through. In this embodiment, the through-hole 54 is formed as the light-passing region.

[0032] The light-shielding regions 52 are arranged in a line, for example, three in the x-axis direction. The passing regions 54 are formed between the light-shielding regions 52. The relative positional relationship between the light-shielding regions 52 and the passing regions 54 is fixed.

[0033] In Figure 2, the optical axis C intersects the middle of the three aligned light-shielding regions 52. The middle light-shielding region 52 in Figure 2 is sometimes referred to as region 52a, which includes the second central axis C2. The second central axis C2 is a virtual axis located in the center of region 52a with respect to the x-axis direction and parallel to the z-axis direction.

[0034] The light-shielding region 42a of the first light-selection region 32, including the first central axis C1, differs in size along the x-axis direction from the light-shielding region 52a of the second light-selection region 34, including the second central axis C2. In this embodiment, the light-shielding region 42a of the first light-selection region 32, including the first central axis C1, is formed to be smaller than the light-shielding region 52a of the second light-selection region 34, including the second central axis C2.

[0035] When the second central axis C2 of the second optical selection region 34 is aligned with the imaging optical axis C of the imaging optical element 22, the light rays B21 and B22 from the object O that form a second angle θ2 (not limited to one angle, and referring to an angle within an appropriate range) with respect to the optical axis C pass through the second optical selection region 34.

[0036] Let the first angle θ1 be an angle within the range of a first maximum angle θ1M or less and a first minimum angle θ1m or more, and let the second angle θ2 be an angle within the range of a second maximum angle θ2M or less and a first minimum angle θ2m or more. In Figure 1, for example, at least one of the following relationships is satisfied: θ1M < θ2M < 90° or 0° < θ1m < θ2m. Both relationships may be satisfied. For example, the relationship θ1M ≤ θ2m is satisfied.

[0037] The processing unit 14 controls the image sensor 24 and the aperture movement mechanism 36. The processing unit 14 can also perform various calculations.

[0038] The processing unit 14 is, for example, a computer. The processing unit 14 includes a processor or integrated circuit (control circuit) including a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), or an FPGA (Field Programmable Gate Array), and a storage medium such as memory. The processor or integrated circuit provided in the processing unit 14 may be one or multiple. The processing unit 14 performs processing by executing a program stored in the storage medium, etc. For example, one example of a program is an imaging program for object P. Another example of a program is a control program for the aperture movement mechanism 36.

[0039] Furthermore, in the processing unit 14, the program executed by the processor may be stored on a computer (server) connected via a network such as the Internet, or on a server in a cloud environment. In this case, the processing unit 14 downloads the program via the network. In other words, it is also preferable that the optical inspection system 10 be controlled by a remote server.

[0040] Next, the operation of the optical inspection system 10 according to this embodiment will be described with reference to Figure 4.

[0041] The subsequent processing will be described as being primarily performed by the processing unit 14, but it may also be performed by the processor or the server.

[0042] The processing unit 14 controls the aperture movement mechanism 36 to align the first central axis C1 of the first optical selection region 32 with the imaging optical axis C of the imaging optical element 22, as shown in Figure 1. At this time, among the light rays from object O, the light rays B11 and B12 that form a first angle θ1 (not limited to one angle, and refer to an angle within an appropriate range) with respect to the optical axis C pass through the light shielding regions 42 of the first optical selection region 32, i.e., the passing region 44. On the other hand, the light rays B21 and B22 (see Figure 2) that form a second angle θ2 (not limited to one angle, and refer to an angle within an appropriate range) different from the first angle θ1 with respect to the optical axis C are shielded by the light shielding region 42 of the first optical selection region 32. As a result, the imaging optical element 22 of the imaging unit 20 images the light rays B11 and B12 that form a first angle θ1 from each object point OP on the object surface onto the (conjugate) image points IP corresponding to those object points OP. In other words, the object surface is captured as a first image by the image sensor 24 using the group of light rays B11 and B12 that form a first angle θ1. The processing unit 14 acquires the first image thus captured (step S1).

[0043] The processing unit 14 controls the aperture movement mechanism 36 to align the light-shielding region 52a, which includes the second central axis C2 of the second light-selection region 34, with the imaging optical axis C of the imaging optical element 22, as shown in Figure 2 (step S2). At this time, among the light rays from the object O, rays B21 and B22 that form a second angle θ2 with respect to the optical axis C pass through the light-shielding regions 52 of the second light-selection region 34, i.e., the passing region 54. On the other hand, rays B11 and B12 that form a first angle θ1 with respect to the optical axis C are shielded by the light-shielding region 52 of the second light-selection region 34. As a result, the imaging optical element 22 of the imaging unit 20 images the rays B21 and B22 that form a second angle θ2 from each object point OP on the object surface onto the (conjugate) image point IP corresponding to those object points OP. In other words, the object surface is captured as a second image by the image sensor 24 using a group of light rays B21 and B22 that form a second angle θ2. The processing unit 14 acquires this second image (step S3). In this way, the optical inspection system 10 acquires multiple different images of the same object surface using the first light-selective aperture 26.

[0044] Therefore, the optical inspection apparatus 12 according to this embodiment can acquire multiple images corresponding to the direction of light rays from an object O by switching and arranging the light shielding region 42a including the first central axis C1 of the first light-selection region 32 of the first light-selection aperture 26 and the light shielding region 52a including the second central axis C2 of the second light-selection region 34 to intersect with the optical axis C.

[0045] Therefore, according to this embodiment, it is possible to provide an optical inspection device 12 capable of acquiring multiple images corresponding to the direction of light rays from an object O, and an optical inspection system 10 having the optical inspection device 12.

[0046] Here, the first image provides intensity information for rays B11 and B12 that form a first angle θ1 at each object point OP on the object surface. The second image provides intensity information for rays B21 and B22 that form a second angle θ2 at each object point OP on the object surface. In other words, the processing unit 14 can obtain intensity information for rays B11, B12, B21, and B22 for the first angle θ1 and the second angle θ2, respectively, from the first and second images. This means that the processing unit 14 can obtain information regarding the scattering angle distribution of each object point OP on the object O (step S4). In particular, when the object O is reflective, the information regarding the scattering angle distribution can be represented by a BRDF (Bidirectional Reflectance Direction Function).

[0047] When the processing unit 14 obtains information regarding the scattering angle distribution, it can obtain information regarding minute irregularities on the object surface (see Non-Patent Literature 1 and Non-Patent Literature 2) (step S5). For example, light reflection on a flat object surface is specular reflection, resulting in a narrow scattering angle distribution. On the other hand, if minute irregularities exist on the object surface, the scattering angle distribution generally becomes wider. Therefore, according to the optical inspection system 10 of this embodiment, the processing unit 14 can perform appropriate calculations based on the image captured using the optical inspection device 12 to obtain information regarding the scattering angle distribution, thereby enabling the detection of the presence or absence of minute irregularities.

[0048] On the other hand, if the optical inspection system 10 uses either the first image or the second image, it can only obtain either the light intensity related to the first angle θ1 or the light intensity related to the second angle θ2. In this case, the processing unit 14 cannot obtain information about the spread of the scattering angle distribution. Therefore, it becomes difficult for the optical inspection system 10 to detect the presence or absence of minute irregularities.

[0049] In this embodiment, the region 42a of the first optical selection region 32 including the first central axis C1 is set as a shielding region, and the region 52a of the second optical selection region 34 including the second central axis C2 is set as a shielding region. For example, the region of the first optical selection region 32 including the first central axis C1 may be formed as a light-transmitting region instead of a shielding region. That is, the first optical selection region 32 shown in Figure 1 may have its shielding region and pass-through region swapped. Similarly, the region of the second optical selection region 34 including the second central axis C2 may be formed as a light-transmitting region instead of a shielding region. That is, the second optical selection region 34 shown in Figure 2 may have its shielding region and pass-through region swapped.

[0050] In this embodiment, an example was described in which the first optical selection region 32 and the second optical selection region 34 of the first optical selection aperture 26 are moved to intersect with respect to the optical axis C using the aperture moving mechanism 36. For example, the first optical selection region 32 and the second optical selection region 34 of the first optical selection aperture 26 may be moved manually with respect to the optical axis C.

[0051] (Variation 1) A modified example 1 of the optical inspection system 10 according to this embodiment is described below. The optical inspection system 10 according to this modified example 1 is shown in Figures 5 and 6.

[0052] Figure 5 shows the optical inspection device 12 of the optical inspection system 10 shown in Figure 1 with an illumination unit 16 and a beam splitter 18 added, and Figure 6 shows the optical inspection device 12 of the optical inspection system 10 shown in Figure 2 with an illumination unit 16 and a beam splitter 18 added.

[0053] Therefore, the optical inspection system 10 according to this modified example 1 further includes an illumination unit 16 and a beam splitter 18, in addition to the optical inspection device 12 and the processing unit 14.

[0054] The lighting unit 16 is equipped with a light source, which may be, for example, white light, or a white LED (Light-Emitting Diode). However, it is not limited to this, and anything that emits light may be used, including an LD (Laser Diode). Alternatively, it may be sunlight, a plasma light source, or a thermal radiation light source (incandescent bulb, halogen lamp, xenon lamp, etc.), or anything else.

[0055] Preferably, the light source of the illumination unit 16 is controlled by the processing unit 14 to turn on and off. When the processing unit 14 turns on the light source of the illumination unit 16 and illumination light is shone from the light source onto the object surface, the processing unit 14 controls the image sensor 24 to acquire an image.

[0056] The beam splitter 18 is placed between object O and imaging optical element 22. The beam splitter 18 intersects the optical axis C of the imaging optical element 22.

[0057] The processing unit 14 causes the illumination light from the illumination unit 16 to be emitted as parallel illumination. The beam splitter 18 directs the illumination light from the illumination unit 16 parallel to the imaging optical axis C of the imaging optical element 22, so that it reaches the object surface. Here, the beam splitter 18 may be unpolarized or polarized.

[0058] Therefore, the illumination unit 16 can irradiate object O with parallel illumination along the imaging optical axis C. Then, as described in the first embodiment, the processing unit 14 acquires a first image with the image sensor 24 when the first light selection region 32 is positioned on the optical axis C, and acquires a second image with the image sensor 24 when the second light selection region 34 is positioned on the optical axis C. In this way, the optical inspection system 10 acquires multiple different images of the same object surface using the first light selection aperture 26.

[0059] This modification allows the direction of the light rays incident on each point OP of object O to be aligned. Therefore, compared to the case where the directions of the light rays incident on each point OP are different, the variation in the scattering angle distribution obtained from the first and second images depending on the direction of the incident light rays can be reduced. Furthermore, by using parallel illumination, the spread of the scattering angle distribution due to minute irregularities obtained from the first and second images can be made more pronounced compared to the case of illumination with a divergence angle. In other words, by using parallel illumination in this modification 1, the processing unit 14 can optically inspect the surface state of object O with greater accuracy compared to the case where the directions of the light rays incident on each point OP are different.

[0060] In both the example shown in Figure 5 and the example shown in Figure 6, by using parallel illumination, if the object point OP is formed on a mirror surface, for example, the light-shielding region 42a including the first central axis C1 and the light-shielding region 52a including the second central axis C2 prevent light rays from entering the light-receiving surface 24a of the image sensor 24. Therefore, the processing unit 14 can also inspect the surface state of the object O by detecting the presence or absence of light incidence.

[0061] (Modification 2) An example of the first optically selective aperture 26 may be the one shown in Figure 7. The first optically selective aperture 26 shown in Figure 7 is parallel to the xy-plane (focal plane fs).

[0062] As shown in Figure 7, for example, the outer diameters of the first optically selected region 32 and the second optically selected region 34 are formed to be the same size D.

[0063] The first light-selection region 32 has a circular central light-shielding region 42a containing a first central axis C1 (see Figures 1 and 2) in its center, and a concentric outer-peripheral light-shielding region 42b around its outer circumference. The region between the central light-shielding region 42a and the outer-peripheral light-shielding region 42b is formed as a passing region 44 that allows light rays (in the first embodiment, reference numerals B11 and B12 (see Figure 1)) to pass through, using an annular space, a transparent film, or a transparent plate.

[0064] In the example of the optical inspection apparatus 12 shown in Figure 1, it is preferable that the first light-selection region 32 of the first light-selection aperture 26 is positioned such that the center (first central axis C1) of the central light-shielding region 42a shown in Figure 7 coincides with or substantially coincides with the optical axis C.

[0065] The second light-selection region 34 has a circular central light-shielding region 52a containing a second central axis C2 (see Figures 1 and 2) in its center, and a concentric outer-peripheral light-shielding region 52b around its outer circumference. The region between the central light-shielding region 52a and the outer-peripheral light-shielding region 52b is formed as a passing region 54 that allows light rays (in the first embodiment, reference numerals B21 and B22 (see Figure 2)) to pass through, using an annular space, a transparent film, or a transparent plate.

[0066] In the example of the optical inspection apparatus 12 shown in Figure 2, it is preferable that the second light-selection region 34 of the first light-selection aperture 26 is positioned such that the center (second central axis C2) of the central light-shielding region 52a shown in Figure 7 coincides with or substantially coincides with the optical axis C.

[0067] For example, the central light shielding region 42a along the radial direction of the first light selection region 32 is formed with a smaller shielding area than the central light shielding region 52a along the radial direction of the second light selection region 34. The outer peripheral light shielding region 42b along the radial direction of the first light selection region 32 has the same outer diameter as the outer peripheral light shielding region 52b along the radial direction of the second light selection region 34, but the ring is thicker and the shielding area is larger.

[0068] The passing regions 44 and 54 may be configured to allow light rays of an appropriate wavelength spectrum to pass through while blocking light rays of other wavelength spectra.

[0069] The light-shielding region 42 and the light-passing region 44 of the first light-selective region 32 shown in Figure 7 may be swapped. Similarly, the light-shielding region 52 and the light-passing region 54 of the second light-selective region 34 shown in Figure 7 may be swapped. The first light-selective region 32 and the second light-selective region 34 may have either the shielding region and the pass-through region swapped.

[0070] (Variation 3) The first optically selective aperture 26 may be, for example, the one shown in Figure 8. The first optically selective aperture 26 shown in Figure 8 is parallel to the xy-plane (focal plane fs).

[0071] As shown in Figure 8, the first optical selection region 32 and the second optical selection region 34 each consist of three rectangles arranged along the x-axis. Assume that the length Lx1 along the x-axis of the first optical selection region 32 is the same as the length Lx2 along the x-axis of the second optical selection region 34, and that the length Ly1 along the y-axis of the first optical selection region 32 is the same as the length Ly2 along the y-axis of the second optical selection region 34.

[0072] The first light-selection region 32 has a central rectangle along the x-axis direction, which is defined as a central light-shielding region 42a containing the first central axis C1 (not shown), and the area outside of it is defined as a pair of outer light-shielding regions 42b. The space between the central light-shielding region 42a and the pair of outer light-shielding regions 42b is formed as a passing region 44 that allows light rays (in the first embodiment, reference numerals B11 and B12 (see Figure 1)) to pass through, for example, by space, a transparent film, or a transparent plate.

[0073] In the example shown in Figure 1, it is preferable that the first optical selective aperture 26 is positioned such that its optical axis C coincides with or substantially coincides with the center of the central light shielding region 42a shown in Figure 8, both in the x-axis direction (width direction) and the y-axis direction (vertical direction) (first central axis C1).

[0074] The second light-selection region 34 is defined as a central light-shielding region 52a, which is a rectangle in the middle along the x-axis direction and includes the second central axis C2 (not shown), and the area outside of it is defined as a pair of outer light-shielding regions 52b. The space between the central light-shielding region 52a and the pair of outer light-shielding regions 52b is formed as a passing region 54 that allows light rays (in the first embodiment, reference numerals B21 and B22 (see Figure 2)) to pass through, for example, by space, a transparent film, or a transparent plate.

[0075] In the example shown in Figure 2, it is preferable that the first light-selective aperture 26 is positioned such that its optical axis C coincides with or substantially coincides with the center of the central light-shielding region 52a shown in Figure 8, both in the x-axis direction (width direction) and in the y-axis direction (vertical direction) (second central axis C2).

[0076] For example, the width in the x-axis direction of the central light shielding region 42a of the first light selection region 32 is smaller than the width in the x-axis direction of the central light shielding region 52a of the second light selection region 34. The pair of outer light shielding regions 42b of the first light selection region 32 have a larger width in the x-axis direction and a larger shielding area than the pair of outer light shielding regions 52b of the second light selection region 34.

[0077] The passing regions 44 and 54 may be configured to allow light rays of an appropriate wavelength spectrum to pass through while blocking light rays of other wavelength spectra.

[0078] The light-shielding region 42 and the light-passing region 44 of the first light-selective region 32 shown in Figure 8 may be swapped. Similarly, the light-shielding region 52 and the light-passing region 54 of the second light-selective region 34 shown in Figure 8 may be swapped. The first light-selective region 32 and the second light-selective region 34 may have either the shielding region and the pass-through region swapped.

[0079] (Second Embodiment) The optical inspection device 12 of the optical inspection system 10 according to this embodiment will be described below with reference to Figures 9 to 15.

[0080] The basic structure of the optical inspection apparatus 12 is the same as that of the optical inspection apparatus 12 of the first embodiment (see Figures 1 and 2), or the optical inspection apparatus 12 of Modification 1 (see Figures 5 and 6). The differences from the first embodiment will be described here.

[0081] Figures 9 and 10 show schematic diagrams of the first optical selective aperture 26 and the second optical selective aperture 28 of the optical inspection apparatus 12 according to this embodiment. Figure 9 is a view of the first optical selective aperture 26 and the second optical selective aperture 28 from the imaging optical element 22 side. Figure 10 is a schematic cross-sectional view along the xy plane containing the optical axis C of the imaging optical element 22 in Figure 9. Figure 11 is a view showing the first optical selective aperture 26 and the second optical selective aperture 28 shown in Figure 9 rotated around the axes of rotation axes 26a and 28a. Figure 12 is a view showing the first optical selective aperture 26 rotated around the axis of rotation axis 26a while maintaining the position of the second optical selective aperture 28 shown in Figure 9.

[0082] Figure 13 is an enlarged view of the aperture edge 64 of the first optically selective aperture 26 in Figure 10. Figure 14 is a modified example of the aperture edge 64 shown in Figure 13.

[0083] Figure 15 is a schematic block diagram of the optical inspection system 10 according to the second embodiment.

[0084] In this embodiment, the imaging unit 20 of the optical inspection device 12 of the optical inspection system 10 comprises an imaging optical element 22, an image sensor 24, a first light-selective aperture 26, a second light-selective aperture 28, and a spacer 27. In Figures 9 to 12, the first light-selective aperture 26, the second light-selective aperture 28, and the spacer 27 are shown, while the imaging optical element 22 and the image sensor 24 are omitted from the illustration.

[0085] As shown in Figures 9 to 12, the first optical selective aperture 26 and the second optical selective aperture 28 are formed in the shape of a disc that can rotate around the axes of rotation axes 26a and 28a, which are parallel to the z-axis direction. Preferably, the rotation axis 26a of the first optical selective aperture 26 and the rotation axis 28a of the second optical selective aperture 28 are positioned parallel to the z-axis at a position on the x-axis offset from the optical axis C of the imaging optical element 22. The discs of the first optical selective aperture 26 and the second optical selective aperture 28 are arranged so that when projected onto a cross-section perpendicular to the optical axis C, a portion of them overlap.

[0086] The second optical selective aperture 28 is positioned on the image sensor 24 side relative to the first optical selective aperture 26. In other words, the first optical selective aperture 26 is positioned on the imaging optical element 22 side relative to the second optical selective aperture 28. A spacer 27 is provided between the first optical selective aperture 26 and the second optical selective aperture 28 to maintain a predetermined distance. The spacer 27 is provided, for example, on the first optical selective aperture 26, and is made of a material that has good sliding properties relative to the second optical selective aperture 28.

[0087] The first optically selective aperture 26 shown in Figures 9 to 12 is formed as a rigid body with an appropriate thickness, as an example. The first optically selective aperture 26 is formed from an opaque shielding material. An example of the first optically selective aperture 26 is a metal or resin material.

[0088] The first light-selective aperture 26 comprises a shielding portion 62 and a plurality of aperture edges 64, each forming a through-hole 64a.

[0089] The shielding portion 62 is formed in a disc shape. The multiple through holes 64a are formed as light-transmitting regions that transmit light. Preferably, the multiple through holes 64a are formed in the shielding portion 62 in a substantially circular shape. The multiple through holes 64a are formed as circular holes of different diameters. Therefore, the multiple aperture edges 64 are formed as the 1-1 light-selective region (first light-selective region), the 1-2 (second light-selective region), the 1-3 light-selective region, ..., the 1-M light-selective region. Thus, for example, the first light-selective aperture 26 has, for example, M different types of light-selective regions (M is a natural number of 2 or more).

[0090] The center of each through-hole 64a formed by each aperture edge 64 is positioned to coincide with or substantially coincide with the optical axis C, i.e., the rotation axis 26a of the first optically selective aperture 26, i.e., the rotation of the shielding portion 62. For this reason, the center of each aperture edge 64 is equidistant from the rotation axis 26a of the shielding portion 62.

[0091] The aperture edge 64 has an inverse taper 66 that widens as it moves away from the image sensor 24 towards the object O. In other words, the aperture edge 64 has a forward taper 66 that narrows as it approaches the image sensor 24. When viewing the cross-section shown in Figure 10, the through-hole 64a formed by the aperture edge 64 is preferably formed in the cross-section shown in Figure 13, for example, in an isosceles trapezoidal shape. For this reason, in the cross-section shown in Figure 13, the aperture edge 64 is preferably formed as a straight line so as little as possible that light from the imaging optical element 22 side or the object O side toward the image sensor 24 side is reflected toward the image sensor 24 side and directed toward the imaging optical element 22 side. Alternatively, in the cross-section shown in Figure 14, the aperture edge 64 is preferably formed as a curve so as little as possible that light from the imaging optical element 22 side or the object O side toward the image sensor 24 side is reflected toward the image sensor 24 side and directed toward the imaging optical element 22 side. The curve in the cross-section of the aperture edge 64 is preferably formed in a concave shape that moves away from the z-axis, compared to the example of a straight line in the cross-section of the aperture edge 64 shown in Figure 13. For this reason, the first optically selective aperture 26 has an appropriate thickness, and when each aperture edge 64 is viewed in the xz cross-section, it is formed in a shape that tapers from the object O side towards the image sensor 24 side.

[0092] As a result, even if unwanted light rays coming towards the image sensor 24 from the side furthest from the image sensor 24 are reflected by the aperture edge 64 of the first light-selective aperture 26, it is possible to block the reflected light from the aperture edge 64 from entering the light-receiving surface 24a of the image sensor 24. On the other hand, if the aperture edge 64 does not have such a taper, some of the light that reaches its side will be reflected, and these reflected unwanted light rays may reach the image sensor 24 and be captured as noise. In other words, by providing a taper to the aperture edge 64, it is possible to prevent noise from entering the image.

[0093] As shown in Figures 9 to 12, the second light-selective aperture 28 comprises a light-transmitting portion 72 and a plurality of light-shielding portions (light-shielding materials) 74.

[0094] The light-transmitting portion 72 is formed in a disc shape. The light-transmitting portion 72 is formed, for example, from a light-transmitting plate (transparent material) that transmits light. Preferably, the light-transmitting plate 72 is made of quartz glass with a thickness of about 0.5 mm. It is also preferable that both sides of the light-transmitting plate 72 are coated with an anti-reflective (AR) coating.

[0095] Furthermore, multiple light-shielding portions 74 are bonded to the surface of the light-transmitting plate 72 that is furthest from the image sensor 24. The multiple light-shielding portions 74 are arranged such that their centers are selectively positioned on the optical axis C of the imaging optical element 22, in accordance with the rotation of the light-transmitting plate 72 around the axis of rotation 26a. The multiple light-shielding portions 74 are formed, for example, by chromium deposition. Preferably, the multiple light-shielding portions 74 are made of light-absorbing material.

[0096] Each light-shielding portion 74 is preferably formed in a circular shape. Each light-shielding portion 74 is formed with a different diameter from the others. Therefore, the multiple light-shielding portions 74 are formed as a 2-1 light-selective region (3rd light-selective region), a 2-2 light-selective region (4th light-selective region), a 2-3 light-selective region, ..., a 2-N light-selective region. For example, the second light-selective aperture 28 has, for example, N different types of light-selective regions (N is a natural number of 2 or more).

[0097] Furthermore, it is preferable that the diameter of the smallest through-hole 64a is the same as or approximately the same as the diameter of the largest light-shielding portion 74.

[0098] The first optically selective aperture 26 has a first aperture movement mechanism 82, and the second optically selective aperture 28 has a second aperture movement mechanism 84. As shown in Figure 15, these first aperture movement mechanism 82 and second aperture movement mechanism 84 are controlled by the processing unit 14.

[0099] The first aperture movement mechanism 82 in this embodiment can independently move the shielding portion 62 of the first optical selective aperture 26 about a rotation axis 26a parallel to the imaging optical axis C. The second aperture movement mechanism 84 in this embodiment can independently move the light transmitting portion 72 of the second optical selective aperture 28 about a rotation axis 28a parallel to the imaging optical axis C. The rotation angles of the first aperture movement mechanism 82 and the second aperture movement mechanism 84 are controlled by a drive source, such as a motor, controlled by the processing unit 14. Therefore, the processing unit 14 controls the aperture movement mechanisms 82 and 84 to set the rotation angles of the shielding portion 62 of the first optical selective aperture 26 and the light transmitting portion 72 of the second optical selective aperture 28 to desired angles. Accordingly, the processing unit 14 selectively positions the central axes of the multiple aperture edges 64 of the first optical selective aperture 26 and the central axes of the multiple light shielding portions 74 of the second optical selective aperture 28 to the optical axis C of the imaging optical element 22. While stepping motors are preferred as the drive sources for the first optical selective aperture 26 and the second optical selective aperture 28, servo motors may also be used.

[0100] Based on the above configuration, the operation of the optical inspection system 10 according to this embodiment will be described.

[0101] In this embodiment, the processing unit 14 can independently rotate the shielding portion 62 of the first optical selective aperture 26 to a desired angle around the rotation axis 26a. Furthermore, the processing unit 14 can independently rotate the light-transmitting portion 72 of the second optical selective aperture 28 to a desired angle around the rotation axis 28a. Therefore, as shown in Figure 9, the processing unit 14 controls the first aperture movement mechanism 82 to move the first-first optical selective region (first optical selective region), which is one of the multiple aperture edges 64 of the first optical selective aperture 26, and the second aperture movement mechanism 84 to move the second-first optical selective region (third optical selective region), which is one of the multiple light-shielding portions 74 of the second optical selective aperture 28, to a position that includes the imaging optical axis C, for example, simultaneously. At this time, the positional relationship in the z-axis direction between the shielding portion 62 of the first optical selective aperture 26 and the light-transmitting portion 72 of the second optical selective aperture 28 does not change due to the spacer 27. This makes it possible to form various shielding or transmission regions in the region including the imaging optical axis C of the focal plane fs or in its vicinity. In other words, the optical inspection apparatus 12 according to this embodiment can form various types of light-selective regions by adjusting the rotation angles of the first light-selective aperture 26 and the second light-selective aperture 28 around the rotation axes 26a and 28a.

[0102] The processing unit 14 then controls the image sensor 24 to capture an image of object O incident on the light-receiving surface 24a of the image sensor 24, thereby acquiring a third image.

[0103] As shown in Figure 11, the processing unit 14 controls the first aperture moving mechanism 82 to move the first-second light-selective region (second light-selective region), which is one of the multiple aperture edges 64 of the first light-selective aperture 26, and the second-second light-selective region (fourth light-selective region), which is one of the multiple light-shielding portions 74 of the second light-selective aperture 28, to a position where both regions, for example, simultaneously include the imaging optical axis C. Then, the processing unit 14 controls the image sensor 24 to capture an image of the object O incident on the light-receiving surface 24a of the image sensor 24, thereby acquiring a fourth image. In this way, the optical inspection system 10 acquires multiple different images of the same object surface using the first light-selective aperture 26.

[0104] Therefore, the optical inspection apparatus 12 according to this embodiment can acquire an image corresponding to the direction of light rays from the same object O by using, for example, a combination of the first-1 optical selection region (first optical selection region) of the first optical selection aperture 26 and the second-1 optical selection region (third optical selection region) of the second optical selection aperture 28, and a combination of the first-2 optical selection region (second optical selection region) of the first optical selection aperture 26 and the second-2 optical selection region (fourth optical selection region) of the second optical selection aperture 28.

[0105] Therefore, according to this embodiment, it is possible to provide an optical inspection device 12 capable of acquiring multiple images corresponding to the direction of light rays from an object O, and an optical inspection system 10 having the optical inspection device 12.

[0106] The processing unit 14 may, for example, acquire a fifth image different from the fourth image after acquiring the third image. The processing unit 14 acquires a fifth image by capturing an image of the object O incident on the light-receiving surface 24a of the image sensor 24 when the combination of the optical selection region of the first optical selection aperture 26 and the optical selection region of the second optical selection aperture 28, which is a different combination from the combination of the 1-1 optical selection region (first optical selection region) and the 2-1 optical selection region (third optical selection region), is simultaneously moved to a position that includes the imaging optical axis C. For example, the second optical selection aperture 28 shown in Figures 9 and 12 is positioned in the same location. As shown in Figure 12, the first optical selection aperture 26 is rotated from the position shown in Figure 9. Therefore, the optical inspection system 10 may acquire a fifth image by rotating at least one of the first optical selection aperture 26 and the second optical selection aperture 28 after acquiring one image (the third image described above).

[0107] For example, suppose the first optical selective aperture 26 is provided with M types of optical selective regions (through holes 64a), and the second optical selective aperture 28 is provided with N types of optical selective regions (light shielding portions 74). In this case, by adjusting the rotation angles of the first optical selective aperture 26 and the second optical selective aperture 28 around their rotation axes 26a and 28a, at least N × M types of optical selective regions can be formed in the region including the imaging optical axis C of the focal plane fs or in its vicinity. Therefore, the processing unit 14 can acquire up to N × M types of images by selectively moving the first optical selective aperture 26 and the second optical selective aperture 28 with respect to an object O without moving the imaging optical element 22 and the image sensor 24. On the other hand, the first optical selective aperture 26 and the second optical selective aperture 28 can only form N types or M types of optical selective regions, respectively. In other words, this embodiment has the effect of dramatically increasing the number of types of optical selective regions that can be formed.

[0108] Increasing the variety of light-selective regions that can be formed improves the angular resolution of the obtainable scattering angle distribution. Therefore, by using the optical inspection apparatus 12 according to this embodiment to capture multiple images of object O and processing them with the processing unit 14, the accuracy of the optical inspection of object O can be improved. Alternatively, increasing the variety of light-selective regions that can be formed using the optical inspection apparatus 12 according to this embodiment allows for further optimization of the light-selective region according to the object being inspected.

[0109] The optical inspection apparatus 12 according to this embodiment can move the first optically selective aperture 26 and the second optically selective aperture 28 with the aperture moving mechanism 36 to form, for example, N × M types of optically selective regions. However, it is not necessary to use all of them; using only some of them is sufficient.

[0110] The second light-selective aperture 28 is composed of a light-transmitting plate 72 that transmits light, and a light-shielding portion 74 that blocks light is joined to the surface of the light-transmitting plate 72 that is farther from the image sensor 24. As a result, an annular aperture is formed at a distance closer to the focal plane fs by the through-hole 64a of the first light-selective aperture 26 and the light-shielding portion 74 of the second light-selective aperture 28. On the other hand, if, for example, the light-shielding portion 74 is formed on the surface of the light-transmitting plate 72 that is closer to the image sensor 24, the light reflected by the light-shielding portion 74 toward the side farther from the image sensor 24 will be reflected again by the back surface of the light-transmitting plate 72, becoming stray light that reaches the image sensor 24 and becomes imaging noise. In other words, this embodiment has the effect of reducing such noise.

[0111] (modified version) The optical inspection apparatus 12 according to this modified example will be described below with reference to Figures 16 and 17.

[0112] The basic structure of the optical inspection apparatus 12 according to this modified example is the same as that of the optical inspection apparatus 12 according to the second embodiment. Here, we will describe the differences from the optical inspection apparatus 12 according to the second embodiment.

[0113] Figures 16 and 17 show schematic diagrams of the first optical selective aperture 26 and the second optical selective aperture 28 of the optical inspection apparatus 12 according to this modified example. Figure 16 is a view of the first optical selective aperture 26 and the second optical selective aperture 28 from the imaging optical element 22 side. Figure 17 is a schematic cross-sectional view along the xy plane containing the optical axis C of the imaging optical element 22 in Figure 16.

[0114] In this modified example, the imaging unit 20 includes an imaging optical element 22, an image sensor 24, a first light-selective aperture 26, a second light-selective aperture 28, and a spacer 27.

[0115] The first optically selective aperture 26 is formed in the same manner as the first optically selective aperture 26 described in the second embodiment.

[0116] The second optically selective aperture 28 is rotatable around the axis of the rotation axis 28a by the second aperture moving mechanism 84, similar to the second optically selective aperture 28 described in the second embodiment.

[0117] The second optically selective aperture 28 comprises a wavelength-selective transmitting plate 92 and a plurality of aperture edges 94, each forming a through-hole 94a.

[0118] The wavelength-selective transmission plate 92 is assumed to transmit light of a specific wavelength spectrum. Here, for example, the wavelength-selective transmission plate 92 is assumed to transmit red light with wavelengths from 500 nm to 700 nm, and block visible light of other wavelengths. In other words, light that passes through the wavelength-selective transmission plate 92 becomes red light.

[0119] Through-holes 94a are formed in the wavelength-selective transmission plate 92. The multiple through-holes 94a are arranged such that the centers of the multiple through-holes 94a are selectively positioned on the optical axis C of the imaging optical element 22 in accordance with the rotation of the wavelength-selective transmission plate 92 around the axis of rotation 28a. When the light source is white, the light that passes through the through-holes 94a becomes white light that includes blue light.

[0120] Furthermore, it is preferable that the diameter of the smallest through-hole 64a is the same as or approximately the same as the diameter of the largest through-hole 94a. For this reason, the through-hole 94a of the second optically selective aperture 28, and the wavelength-selective transmission plate 92 outside the aperture edge 94 forming the through-hole 94a, are formed as a plurality of transmission wavelength spectral regions that transmit light of at least two different wavelengths. In other words, the second optically selective aperture 28 has a plurality of transmission wavelength spectral regions that transmit light of at least two different wavelengths.

[0121] The image sensor 24 is configured to independently receive, at least, red light with a wavelength of 500 nm to 700 nm and blue light with a different wavelength spectrum and a peak wavelength of 450 nm at each pixel. In each pixel, the channel that receives red light is denoted as R, and the channel that receives blue light is denoted as B.

[0122] Based on the above configuration, the operation of the optical inspection system 10 according to this modified example will be described.

[0123] The processing unit 14 allows the first optical selective aperture 26 and the second optical selective aperture 28 of this embodiment to be rotated independently around their respective rotation axes 26a and 28a. This makes it possible to form various shielding regions, red light transmission regions, or blue-red light transmission regions in or near the region including the imaging optical axis C of the focal plane fs. In other words, by adjusting the rotation angles of the shielding portion 62 of the first optical selective aperture 26 and the wavelength-selective transmission plate 92 of the second optical selective aperture 28, various types of optical selective regions can be formed.

[0124] For example, suppose the first optical selective aperture 26 is provided with multiple aperture edges 64 as M types (where M is a natural number of 2 or more) of optical selective regions, and the second optical selective aperture 28 is provided with multiple aperture edges 94 and wavelength-selective transmitting plates 92 on the outer periphery of each aperture edge 94 as N types (where N is a natural number of 2 or more) of optical selective regions. In this case, by adjusting the rotation angles of the first optical selective aperture 26 and the second optical selective aperture 28, at least N × M types of optical selective regions can be formed in the region including the imaging optical axis C of the focal plane fs or in its vicinity. On the other hand, the first optical selective aperture 26 or the second optical selective aperture 28 can only form N types or M types of optical selective regions, respectively. In other words, this embodiment has the effect of dramatically increasing the number of types of optical selective regions that can be formed.

[0125] Increasing the variety of light-selective regions that can be formed improves the angular resolution of the obtainable scattering angle distribution. Therefore, by using the optical inspection device 12 according to this modified example to capture multiple images of object O and processing them with the processing unit 14, the accuracy of the optical inspection of object O can be improved. Alternatively, increasing the variety of light-selective regions that can be formed using the optical inspection device 12 according to this modified example allows for further optimization of the light-selective region according to the inspection target.

[0126] In this modified example, for instance, when the relative positions of the two light-selective apertures 26 and 28 are set as shown in Figures 16 and 17, the light can be divided into two different color regions: a red light transmission region and a blue-red light transmission region. This has the effect that when the processing unit 14 acquires an image using the image sensor 24 of the imaging unit 20, it can simultaneously distinguish scattering angle distribution information at different angles by color. In other words, the optical inspection system 10 according to this embodiment has the effect of increasing the amount of scattering angle distribution information that can be acquired in a single image.

[0127] An increase in the scattering angle distribution information that can be acquired in a single operation allows the processing unit 14 to optically inspect the surface state of object O with greater accuracy. Alternatively, an increase in the scattering angle distribution information that can be acquired in a single operation allows the processing unit 14 to optically inspect the surface state of object O at a faster speed.

[0128] According to at least one embodiment described above, it is possible to provide an optical inspection device 12 capable of acquiring multiple images corresponding to the direction of light rays from an object O, and an optical inspection system 10 having the optical inspection device 12.

[0129] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0130] 10…Optical inspection system, 12…Optical inspection device, 14…Processing unit, 16…Illumination unit, 18…Beam splitter, 20…Imaging unit, 22…Imaging optical element (imaging lens), 24…Image sensor, 24a…Light receiving surface, 26…First light-selective aperture, 26a…Rotation axis, 27…Spacer, 28…Second light-selective aperture, 28a…Rotation axis, 32…First light-selective region, 34…Second light-selective region, 36…Aperture movement mechanism, 42,42a…Shielding region, 42b…Outer shielding region (outer periphery) Shielding region), 44...passing region, 52, 52a...shielding region, 52b...outer shielding region (outer peripheral shielding region), 54...passing region, 62...shielding part, 64...aperture edge, 64a...through hole, 66...taper, 72...light transmitting plate (light transmitting part), 74...light shielding part, 82...first aperture moving mechanism, 84...second aperture moving mechanism, 92...wavelength selective transmitting plate, 94...aperture edge, 94a...through hole, B11, B12, B21, B22...light rays, C...optical axis, C1...first central axis, C2...second central axis.

Claims

1. An imaging optical element having an imaging optical axis, An image sensor having a light-receiving surface that intersects the aforementioned imaging optical axis, A movable first optically selective aperture and As a preparation, The first optically selective aperture has a first optically selective region and a second optically selective region that selectively transmit light from an object in different directions. The first optically selective aperture is positioned at or near the focal plane of the imaging optical element. When the first light-selection region of the first light-selection aperture moves to a position that includes the imaging optical axis, the image sensor captures an image of the object incident on the light-receiving surface through the imaging optical element and the first light-selection region to acquire a first image. When the second light-selection region of the first light-selection aperture moves to a position that includes the imaging optical axis, the image sensor captures an image of the object incident on the light-receiving surface through the imaging optical element and the second light-selection region to acquire a second image. Optical inspection equipment.

2. The system includes a second optically selective aperture that is movable independently of the first optically selective aperture, The second optically selective aperture has a third optically selective region and a fourth optically selective region that selectively transmit light from the object in different directions. The second optically selective aperture is positioned at or near the focal plane of the imaging optical element. At least one of the first or second optical selection region of the first optical selection aperture, and at least one of the third and fourth optical selection regions of the second optical selection aperture, can be moved simultaneously to a position that includes the imaging optical axis. The optical inspection apparatus according to claim 1.

3. When the first light-selection region of the first light-selection aperture and the third light-selection region of the second light-selection aperture are both moved simultaneously to a position that includes the imaging optical axis, the image sensor captures an image of the object incident on the light-receiving surface and acquires a third image. When the second light-selection region of the first light-selection aperture and the fourth light-selection region of the second light-selection aperture are both moved simultaneously to a position that includes the imaging optical axis, the image sensor captures an image of the object incident on the light-receiving surface and acquires a fourth image. The optical inspection apparatus according to claim 2.

4. When the first light-selection region of the first light-selection aperture and the third light-selection region of the second light-selection aperture are both moved simultaneously to a position that includes the imaging optical axis, the image sensor captures an image of the object incident on the light-receiving surface and acquires a third image. When the combination of the optical selection region of the first optical selection aperture and the optical selection region of the second optical selection aperture is different from the combination of the first optical selection region and the third optical selection region, and these combinations are simultaneously moved to a position that includes the imaging optical axis, the image sensor captures an image of the object incident on the light-receiving surface and acquires a fifth image. The optical inspection apparatus according to claim 2.

5. The first light-selective aperture has at least a light-shielding region that blocks light and a light-transmitting region provided in the light-shielding region. The optical inspection apparatus according to claim 1 or claim 2.

6. The second light-selective aperture has a light-transmitting region that transmits light and a light-shielding region provided in the light-transmitting region that at least blocks light. The optical inspection apparatus according to claim 2.

7. The second optically selective aperture has multiple transmission wavelength spectral regions that transmit light of at least two different wavelengths. The optical inspection apparatus according to claim 2.

8. The light-transmitting region of the first light-selective aperture is formed as a plurality of through holes, Each of the aforementioned through holes has a taper that widens in the direction away from the image sensor. The optical inspection apparatus according to claim 5.

9. The light-transmitting region of the second light-selective aperture is formed by a light-transmitting plate that transmits light. The light-shielding region of the second light-selective aperture is formed by bonding a light-shielding material to the surface of the light-transmitting plate that is furthest from the image sensor. The optical inspection apparatus according to claim 6.

10. The first and second optically selective apertures each have a rotation axis parallel to the imaging optical axis, and are able to move independently around them. The optical inspection apparatus according to claim 2.

11. It shall be equipped with a lighting unit, The illumination unit is capable of illuminating the object with parallel illumination along the imaging optical axis. The optical inspection apparatus according to claim 1 or claim 2.

12. An optical inspection apparatus according to claim 1 or claim 2, A processor that uses the first image and the second image to acquire scattering angle distribution information of the object. An optical inspection system having the following features.

13. An optical inspection apparatus according to claim 1 or claim 2, An aperture movement mechanism for moving the first light-selective aperture, A processor that controls the aperture movement mechanism and controls the movement of the first optically selective aperture. An optical inspection system having the following features.

Images