Optical device, optical inspection system, imaging method of object, and imaging program of object

Abstract

To provide an optical device capable of imaging a relatively moving object even from an oblique direction in addition to from right opposite position.SOLUTION: The optical device has an illumination part, a light receiving part and a processing part. The illumination part illuminates an object relatively moving in a prescribed direction with light. The illumination part can illuminate a first illumination point of the object with first wavelength light and a second illumination point different from the first illumination point of the object with second wavelength light different from the first wavelength. A line connecting the first illumination point and the second illumination point intersects a prescribed direction. The light receiving part relatively moves to the object while maintaining the positional relationship with the illumination part, and comprises a first light receiving element for receiving light transmitting through the first illumination point and the second illumination point of the object. The first light receiving element can independently and distinguishably receive first wavelength and second wavelength. The processing part images the object on the basis of light reception signal obtained by receiving the light transmitting through the first illumination point and the second illumination point.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Embodiments of the present invention relate to an optical device, an optical inspection system, a method for imaging an object, and a program for imaging an object. [Background technology]

[0002] Non-contact imaging technology for objects being transported is becoming increasingly important in a variety of industries. Conventional methods involve illuminating an object and imaging it with a camera. However, when imaging a flat object with a camera, there is a problem in that areas are out of focus, meaning areas cannot be imaged, when capturing an image from an oblique angle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 5,675,407 [Non-patent literature]

[0004] [Non-Patent Document 1] Hiroshi Ohno & Takahiro Kamikawa, “One-shot BRDF imaging system to obtain surface properties,” Optical Review volume 28, pages655-661 (2021). Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the present invention is to provide an optical device, an optical inspection system, an object imaging method, and an object imaging program that can image a relatively moving object not only from a directly facing position but also from an oblique position. [Means for solving the problem]

[0006] According to an embodiment, an optical device includes an illumination unit, a light receiving unit, and a processing unit. The illumination unit illuminates light onto an object moving relatively in a predetermined direction. The illumination unit can illuminate a first illumination point on the object with light of a first wavelength and illuminate a second illumination point on the object different from the first illumination point with light of a second wavelength different from the first wavelength. A line segment connecting the first illumination point and the second illumination point intersects with the predetermined direction. The light receiving unit moves relative to the object while maintaining a positional relationship with the illumination unit, and includes a first light receiving element that receives light that has passed through the first illumination point on the object and light that has passed through the second illumination point. The first light receiving element can distinguish between the first wavelength and the second wavelength and receive them independently. The processing unit performs imaging of the object based on light receiving signals received from the light that has passed through the first illumination point and the second illumination point. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic perspective view of an optical inspection system according to a first embodiment. [Figure 2] FIG. 1 is a schematic block diagram of an optical inspection system according to an embodiment. [Figure 3] 1 is a flowchart showing an example of a processing flow in an optical inspection system according to an embodiment. [Figure 4] FIG. 10 is a diagram showing an example of an illumination unit of an optical device according to a modified example of the first embodiment. [Figure 5] FIG. 10 is a schematic perspective view of an optical inspection system according to a second embodiment. [Figure 6] FIG. 10 is a schematic perspective view of an optical inspection system according to a first modified example of the second embodiment. [Figure 7] FIG. 10 is a schematic cross-sectional view of an optical inspection system according to a second modification of the second embodiment. [Figure 8] FIG. 10 shows a schematic perspective view of an optical inspection system according to a third embodiment. [Figure 9]11 is a schematic top view of a first wavelength and a second wavelength from a light source of an illumination unit of an optical inspection system according to a third embodiment, and an object being transported on a transport unit of a transport device. FIG. [Figure 10] A schematic top view of a first wavelength and a second wavelength from a light source of an illumination section of an optical inspection system and an object being transported on a transport section of a transport device after an appropriate time has passed since the time shown in Figure 9. [Figure 11] FIG. 11 is a schematic perspective view of an optical inspection system according to a modified example of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Each embodiment 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 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 explanations will be omitted where appropriate.

[0009] In this specification, light is a type of electromagnetic wave, and includes X-rays, ultraviolet light, visible light, infrared light, microwaves, etc. In this embodiment, the light is considered to be visible light, with a wavelength in the range of 400 nm to 800 nm, for example.

[0010] (First embodiment) An optical inspection device 10 according to this embodiment will be described below with reference to FIGS.

[0011] Fig. 1 shows a schematic perspective view of an optical inspection system 10 according to this embodiment. Fig. 2 shows a schematic block diagram of the optical inspection system 10 according to this embodiment. Fig. 3 shows a flowchart of optical inspection according to an optical inspection program of the optical inspection system 10 according to this embodiment.

[0012] As shown in Figures 1 and 2, an optical inspection system 10 according to this embodiment includes a transport device 12 that transports an object P in a predetermined direction, and an optical device 14 that is used together with the transport device 12. An xyz Cartesian coordinate system is shown in Figure 1. The direction along the x axis is the transport direction of the object P by the transport unit 12a, which will be described later. The direction along the y axis is the direction perpendicular to the transport direction of the object P. The xy plane is preferably a plane parallel to the floor, but is not limited to this. The direction along the z axis is the direction perpendicular to the xy plane. The direction along the z axis is preferably the vertical direction, but is not limited to this depending on the position of the xy plane.

[0013] The conveying device 12 conveys the object P on the conveying section 12a in a predetermined direction by the conveying section 12a. In this embodiment, the conveying direction may be any direction, but here, the conveying direction is the x-axis in FIG. 1. However, the conveying device 12 may also move the light receiving section 40 and the illumination section 30 (described later) of the optical device 14 relative to the object P. In other words, in the optical inspection system 10, any means may be used as long as it changes the relative positional relationship of the object P with respect to the light receiving section 40 and the illumination section 30 while maintaining the positional relationship between the light receiving section 40 and the illumination section 30. These means are collectively referred to as the conveying means of the optical inspection system 10.

[0014] The conveying section 12a of the conveying device 12 may be of any type, such as a belt conveyor type, a linear motor type, a torque screw (ball screw) type, a parallel link type, a roller conveyor type, an air conveyor type, or a chain conveyor type.

[0015] In this embodiment, for the sake of simplicity, it is assumed that the conveying device 12 conveys the object P by the conveying section 12a in a straight conveying direction along the x-axis.

[0016] The optical device 14 includes an illumination unit 30 that illuminates an object P that moves relatively in a predetermined direction with light, a light receiving unit 40 that receives light reflected from the object P, and a processing unit 50.

[0017] The illumination unit 30 includes a light source 32. The light source (illumination) 32 of the illumination unit 30 emits light (or light rays) of a first wavelength L1 and a second wavelength L2. Hereinafter, the light having the first wavelength L1 may be simply referred to as the first wavelength L1. Similarly, the light having the second wavelength L2 may be simply referred to as the second wavelength L2. The point on the object P at which the first wavelength L1 reaches is referred to as the first illumination point P1, and the point on the object P at which the second wavelength L2 reaches is referred to as the second illumination point P2. The illumination unit 30 includes a white light source 32 such as a white light-emitting diode (LED), halogen lamp, fluorescent lamp, incandescent lamp, high-intensity discharge lamp (HID lamp), or metal halide lamp. However, the light source 32 is not limited to this, and may also be an array of multiple monochromatic lasers of various colors. When the light source 32 is a white light source, the illumination unit 30 may use a prism or a diffraction grating to separate the light from the white light source 32 into light of a first wavelength and light of a second wavelength. Alternatively, the illumination unit 30 may project light of the first wavelength L1 and light of the second wavelength L2 onto the object P using a projection device such as a color projector.

[0018] The light receiving unit 40 includes a first light receiving element 42. The first light receiving element 42 receives light of a first wavelength L1 and light of a second wavelength L2 and can distinguish between them. That is, the first light receiving element 42 can separate light of the first wavelength L1 and light of the second wavelength L2. However, the first light receiving element 42 has a single light receiving aperture. Such a light receiving element is sometimes called a single-pixel light receiving element. The first light receiving element 42 may be, for example, a photodiode (PD) or a photomultiplier tube. The first light receiving element 42 may be, for example, a dispersive spectrometer that combines a prism or a diffraction grating with a photodiode. Alternatively, it may be a spectrometer that utilizes optical interference. For example, it may be a spectrometer that uses a Michelson interferometer or a Fabry-Perot interferometer. Alternatively, it may be a spectrometer that combines a prism or a diffraction grating with multiple photomultiplier tubes. That is, the first light receiving element 42 may be any element that can distinguish between light of the first wavelength L1 and light of the second wavelength L2 and convert each into an independent light receiving signal.

[0019] It is preferable that the relative positional relationship (position, posture, orientation) between the light source 32 of the illumination unit 30 and the first light receiving element 42 of the light receiving unit 40 is fixed when a series of images of the object P is being performed.

[0020] The line segment connecting the first illumination point P1 and the second illumination point P2 intersects with a line (x-axis) along the conveying direction of the conveying device 12. In other words, the line segment connecting the first illumination point P1 and the second illumination point P2 is not parallel to the line along the conveying direction of the conveying device 12. In other words, the angle θ that the line segment connecting the two illumination points P1 and P2 makes with the line along the conveying direction is greater than 0° and less than 180°.

[0021] In this specification, obtaining information that reflects the reflectance distribution or transmittance distribution of the object P is referred to as imaging.

[0022] The processing unit 50 controls the illumination unit 30 and the light receiving unit 40. The processing unit 50 may also control the transport device 12.

[0023] The processing unit 50 grasps the position of the light source 32 of the illumination unit 30, the irradiation direction of the light of the first wavelength and the second wavelength emitted from the light source 32, the first light receiving element 42, and the three-dimensional relative positional relationship of the illumination unit 30 and the first light receiving element 42 of the light receiving unit 40 with respect to the transport device 12. In other words, the processing unit 50 grasps the relative position, posture, and orientation of the light source 32 of the illumination unit 30 and the first light receiving element 42 of the light receiving unit 40.

[0024] The processing unit 50 is, for example, a computer. The processing unit 50 includes a processor or integrated circuit (control circuit) including a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or the like, and a storage medium such as a memory. The processing unit 50 may include one or more processors or integrated circuits. The processing unit 50 performs processing by executing a program or the like stored in a storage medium or the like. For example, one example of the program is an imaging program for the object P.

[0025] In addition, in the processing unit 50, the program executed by the processor may be stored in a computer (server) connected via a network such as the Internet or a server in a cloud environment, etc. In this case, the processing unit 50 downloads the program via the network.

[0026] The operation of the optical inspection system 10 according to the embodiment described above will be described with reference to FIG.

[0027] In this embodiment, an example will be described in which the relative positions, postures, and orientations of the illumination unit 30 and the light receiving unit 40 are fixed, and the object P is transported by the transport unit 12a of the transport device 12, i.e., the object P moves in a predetermined direction. Here, the object P is transported by the transport unit 12a of the transport device 12.

[0028] The processing unit 50 operates the light source 32 of the illumination unit 30 to irradiate light toward the object P on the conveyance unit 12a of the conveyance device 12 (step S1). The area illuminated by the light L1 and L2 from the light source 32 of the illumination unit 30 is called the illumination field F. The object P conveyed by the conveyance device 12 is illuminated by the light from the light source 32 of the illumination unit 30. The light source 32 of the illumination unit 30 emits light of a first wavelength L1 and a second wavelength L2, which are reflected or transmitted by the surface of the object P. In this specification, when light is reflected or transmitted by the object P, it is said that the light has passed through the object P. In this embodiment, the object P is assumed to be reflective, and light is reflected by the surface of the object P. However, this is not limited to this, and the object P may be transparent, translucent, or opaque. The points at which the light of the first wavelength L1 and the light of the second wavelength L2 reach the object P are called the first illumination point P1 and the second illumination point P2, respectively. The light source 32 of the illumination unit 30 emits light so that the first illumination point P1 and the second illumination point P2 are different points on the object P.

[0029] The processing unit 50 causes the first light receiving element 42 to receive the light that has passed through (or is reflected in this embodiment) the first illumination point P1 and the second illumination point P2 (step S2). However, the processing unit 50 is not limited to this. After activating the light source 32 of the illumination unit 30 to irradiate light toward the object P on the conveyance unit 12a of the conveyance device 12 (step S1), the processing unit 50 may control the illumination unit 30 to cause the first light receiving element 42 to receive the light that has passed through (or is reflected in this embodiment) the first illumination point P1 and the second illumination point P2 (step S2). In other words, the processing unit 50 may operate only the illumination unit 30. The first light receiving element 42 acquires the light of the first wavelength L1 and the light of the second wavelength L2 as independent light receiving signals for each wavelength. The intensities of these light receiving signals serve as indicators of the magnitude of the reflectance at the first illumination point P1 and the second illumination point P2, respectively. In other words, if the reflectance of each of the illumination points P1 and P2 is high, the intensity of the received light signal will also be high accordingly. However, if the object P is transparent, the transmittance will be used instead of the reflectance.

[0030] Reflectance and transmittance are important characteristics of the object P, and acquiring their distributions or the distributions of their indices in the object P is called imaging. The processing unit 50 thus performs imaging at the first illumination point P1 and the second illumination point P2 (step S3). That is, the processing unit 50 images the object P based on the light reception signal from the first light receiving element 42.

[0031] In addition, the processing unit 50 can image the object P continuously from the upstream end to the downstream end of the object P along the conveying direction by repeating steps S1 to S3 on the object P being conveyed by the conveying unit 12a.

[0032] When the illumination unit 30 irradiates the first illumination point P1 and the second illumination point P2 with light of the same wavelength, for example, when irradiating both with light of the first wavelength L1, even if the light reflected from the illumination points P1 and P2 is received by the first light receiving element 42, the illumination points P1 and P2 cannot be identified. This is because the first light receiving element 42 can only acquire the sum of the intensities of the light from the first illumination point P1 and the second illumination point P2 as a light reception signal. In this case, it is not possible to simultaneously image the two different illumination points P1 and P2. In contrast, in this embodiment, the first illumination point P1 and the second illumination point P2 are irradiated with light of different wavelengths, which has the advantage of allowing the two illumination points P1 and P2 to be simultaneously imaged.

[0033] Furthermore, if the first light receiving element 42 cannot distinguish between the light of the first wavelength L1 and the light of the second wavelength L2, that is, if it cannot acquire the light receiving signals of the light L1 and the light L2 independently, it will not be possible to identify the first illumination point P1 and the second illumination point P2 from the light receiving signals. In contrast, in this embodiment, the first light receiving element 42 can distinguish between the first wavelength L1 and the second wavelength L2, which has the advantage that the processing unit 50 can simultaneously image the two illumination points P1 and P2.

[0034] While the object P is being transported by the transport section 12a of the transport device 12, the relative positions of the first illumination point P1 and the second illumination point P2 with respect to the object P change over time. At this time, the first light-receiving element 42 receives the reflected light from each point independently over time. This allows the reflectance distribution of the object P to be acquired along the transport direction of the transport section 12a. In other words, the processing section 50 of the optical inspection system 10 can image two different lines on the object P while scanning them over time. Meanwhile, consider a case where the line segment connecting the first illumination point P1 and the second illumination point P2 is parallel to a line along the transport direction. In this case, the processing section 50 scans and images a single line passing through the first illumination point P1 and the second illumination point P2 over time. In other words, the processing section 50 cannot simultaneously scan and image more than one line. In contrast to this, in this embodiment, the line segment connecting the first illumination point P1 and the second illumination point P2 is set to intersect with a line (x-axis) along the transport direction, which has the advantage that the processing unit 50 can image the object P while simultaneously scanning not one line but two lines, i.e., lines passing through the first illumination point P1 and the second illumination point P2.

[0035] According to this embodiment, the processing unit 50 performs imaging based on the light reception signal from the first light receiving element 42. At this time, the optical device 14 does not need to focus using an imaging optical element such as a lens to acquire the light reception signal. In other words, there is no need to adjust the focus for imaging by adjusting the distance to the light receiving unit 40 or using an imaging optical element or the first light receiving element 42, which is an advantage of being focus-free. As a result, by using the optical device 14 according to this embodiment, it is possible to image an object P, such as a planar subject, not only from directly above, which is a position directly facing the object P, but also from an oblique angle.

[0036] In the present embodiment, an example has been described in which the illumination unit 30 of the optical device 14 illuminates the object P with light of a first wavelength L1 and a second wavelength L2. For example, it is also preferable to illuminate a line segment connecting the first illumination point P1 and the second illumination point P2 with light of wavelengths L3, L4, ... different from both the first wavelength L1 and the second wavelength L2, and to obtain the light of those wavelengths by dispersing it using the first light receiving element 42. In this case, the wavelengths L3, L4, ... of the light illuminated on the line segment between the first illumination point P1 and the second illumination point P2 are different from each other.

[0037] The processing unit 50 repeats steps S1 to S3 on the object P being transported by the transport unit 12a, dispersing and receiving light of wavelengths L1, L2, L3, L4, ... with the first light receiving element 42, thereby imaging the object P continuously from the upstream end to the downstream end of the object P along the transport direction.

[0038] In the present embodiment, the optical device 14 is described as being equipped with the processing unit 50. For example, the processing unit 50 may be located at a location separate from the optical device 14, whether domestic or overseas, as long as it can process the light reception signal of the first light receiving element 42 of the light receiving unit 40.

[0039] In the optical inspection system 10 according to the present embodiment, an example has been described in which the object P is moved in a predetermined direction using the transport unit 12a. For example, while the object P is stationary, the illumination unit 30 and the light receiving unit 40 may be moved while irradiating the object P with light including a first wavelength L1 and a second wavelength L2, while maintaining the relative positional relationship (position, posture, orientation) between the illumination unit 30 and the light receiving unit 40. Alternatively, the object P, the illumination unit 30, and the light receiving unit 40 may be moved while irradiating the object P with light including a first wavelength L1 and a second wavelength L2, while maintaining the relative positional relationship (position, posture, orientation) between the illumination unit 30 and the light receiving unit 40.

[0040] As described above, the optical device 14 according to this embodiment includes an illumination unit 30 that illuminates light onto an object moving relatively in a predetermined direction, a light receiving unit 40, and a processing unit 50. The illumination unit 30 is configured to illuminate a first illumination point P1 on the object P with light of a first wavelength L1 and illuminate a second illumination point P2 on the object P that is different from the first illumination point P1 with light of a second wavelength L2 that is different from the first wavelength L1. A line segment connecting the first illumination point P1 and the second illumination point P2 intersects with a predetermined direction (e.g., the transport direction). The light receiving unit 40 moves relative to the object P while maintaining its positional relationship (position, posture, and orientation) with the illumination unit 30, and includes a first light receiving element 42 that receives light that has passed through the first illumination point P1 and the second illumination point P2 on the object P. The first light receiving element 42 can distinguish between the first wavelength L1 and the second wavelength L2 and receive them independently. The processing unit 50 performs imaging of the object P based on light reception signals obtained by receiving light that has passed through the first illumination point P1 and the second illumination point P2.

[0041] The imaging method for the object P includes: illuminating a first illumination point P1 of the object P with light of a first wavelength L1 from the illumination unit 30, and illuminating a second illumination point P2 different from the first illumination point P1 of the object P with light of a second wavelength L2 different from the first wavelength L1, while maintaining the relative position (position, posture, orientation) of the optical device 14 having the illumination unit 30 and the light receiving unit 40, and moving the object in a predetermined direction relative to the illumination unit 30 and the light receiving unit 40; receiving the light that has passed through the first illumination point P1 of the object P and the light that has passed through the second illumination point P2 with a light receiving unit 40 having a first light receiving element 42 that can distinguish between the first wavelength L1 and the second wavelength L2 and receive them independently; and imaging the object P based on light receiving signals of the light that has passed through the first illumination point P1 and the second illumination point P2 received by the light receiving unit 40. Note that the line segment connecting the first illumination point P1 and the second illumination point P2 intersects with a predetermined direction (for example, the transport direction).

[0042] The imaging program for the object P maintains the relative position of the optical device 14 having the illumination unit 30 and the light receiving unit 40, and while moving the object P in a predetermined direction relative to the illumination unit 30 and the light receiving unit 40, illuminates a first illumination point P1 of the object P with light of a first wavelength L1 from the illumination unit 30, and illuminates a second illumination point P2 different from the first illumination point P1 of the object P with light of a second wavelength L2 different from the first wavelength L1. The line segment connecting the first and second illumination points P1 and P2 intersects with a predetermined direction, and the light that has passed through the first illumination point P1 of the object P and the light that has passed through the second illumination point P2 are received by a light receiving unit 40 that has a first light receiving element 42 that can distinguish between the first wavelength L1 and the second wavelength L2 and receive them independently, and the computer is caused to perform imaging of the object P based on the light receiving signals received by the light receiving unit 40 of the light that has passed through the first illumination point P1 and the second illumination point P2.

[0043] According to this embodiment, an optical device 14, an optical inspection system 10, an imaging method for an object P, and an imaging program for an object P can be provided that can image a relatively moving object P not only from a direct facing position but also from an oblique position.

[0044] (Variation 1) Fig. 4 shows an example of the illumination unit 30 of the optical device 14 in Modification 1 of the optical inspection system 10 according to this embodiment. Fig. 4 is a cross-sectional view perpendicular to the conveying direction. Following Fig. 1, an xyz Cartesian coordinate system is taken as shown in Fig. 4.

[0045] The illumination unit 30 includes a light source 32, such as an LED light source, an aperture 33, a diffraction grating 34, and an illumination lens 35. The diffraction grating 34 is positioned so as to include the focal point of the illumination lens 35 or its vicinity. Light emitted from the light source 32 passes through the aperture 33 and reaches the diffraction grating 34. The light that passes through the aperture 33 is incident on the diffraction grating 34 in a direction perpendicular to the diffraction surface. The light that enters the diffraction grating 34 is converted into a group of light rays with different directions for each wavelength. This group of light rays becomes divergent light and reaches the illumination lens 35. The divergent light rays are then converted into parallel light by the illumination lens 35 and irradiated onto the transport unit 12a (see FIG. 1) outside the illumination unit 30. As a result, the light of different wavelengths reaches the object P at different illumination points. Because the group of light rays is parallel when it reaches the object P, the group of light rays points in the same direction at all illumination points. This allows the incident directions of the first illumination point P1, illuminated with light of the first wavelength L1, and the second illumination point P2, illuminated with light of the second wavelength L2, to be aligned parallel to each other. Furthermore, if the first light-receiving element 42 is located sufficiently far from the illumination points P1 and P2, the directions of the reflected light of the first wavelength L1 and the second wavelength L2 can also be aligned. It is known that reflectance depends on the incident and reflected directions. This directional dependency can be described by a bidirectional reflectance distribution function (BRDF). The processing unit 50 can accurately identify differences in the surface characteristics of the object P by comparing the BRDFs based on the light-receiving signals from the light-receiving unit 40. To accurately obtain the distribution of surface characteristics on the object P, it is necessary to compare the reflectances by aligning the incident and reflected directions of light from the illumination unit 30 of the optical device 14. In other words, by aligning the conditions of these two directions (incident and reflected directions), the processing unit 50 can accurately compare the BRDFs and more accurately identify surface characteristics.

[0046] The above-described illumination unit 30 of the optical device 14 of this variant example 1 allows the incident direction and reflection direction to be aligned regardless of the position on the object P, so the optical inspection system 10 of this variant example 1 has the advantage of being able to more accurately acquire the surface characteristics of the object P, i.e., information about the object P.

[0047] (Variation 2) Modification 2 is a further modification of the first embodiment and modification 1. In the first embodiment and modification 1, examples using light of a first wavelength L1 and a second wavelength L2 have been described. The optical device 14 according to modification 2 may use light of more than two (three or more) different wavelengths. That is, light of wavelengths ranging from 450 nm to 750 nm, for example, may be dispersed and irradiated over the entire irradiation field F intersecting the transport direction. At the same time, the first light-receiving element 42 in the light-receiving unit 40 may be configured to receive light of the multiple wavelengths by dispersing them. This has the effect of enabling imaging of the object P not only at the illumination points P1 and P2 but also over the entire irradiation field F between the illumination points P1 and P2.

[0048] For example, by using the diffraction grating 34 shown in FIG. 4, the illumination unit 30 can irradiate the surface of the object P with light whose wavelength gradually increases from the first illumination point P1 to the second illumination point P2, or whose wavelength gradually decreases from the first illumination point P1 to the second illumination point P2. This allows the illumination unit 30 to continuously change the light between the first illumination point P1 and the second illumination point P2 like a rainbow. Therefore, by using the diffraction grating 34, the illumination unit 30 can generate light of a first wavelength L1 and light of a second wavelength L2 at different illumination positions. The wavelengths between the illumination points P1 and P2 in the illumination field F can all be different.

[0049] The first light receiving element 42 of the light receiving unit 40 may be capable of separating and receiving light into not only two wavelengths L1 and L2 but also three or more wavelengths. If the first light receiving element 42 of the light receiving unit 40 can separate and receive light into a greater number of wavelengths, it will be possible to image images of illumination points corresponding to each wavelength between the first illumination point P1 and the second illumination point P2.

[0050] Since the object P is transported by the transport unit 12a while maintaining the relative positional relationship (position, posture, orientation) between the illumination unit 30 and the light receiving unit 40, by using the optical device 14 of this modified example 2, it is possible to image the surface of the object P while simultaneously scanning the lines passing through the points between the first illumination point P1 and the second illumination point P2.

[0051] (Variation 3) In the first embodiment and the above-described modified examples 1 and 2, the representative points of the area illuminated by the light of the first wavelength L1 and the light of the second wavelength L2 are defined as illumination points. However, the illumination areas of the light of each wavelength L1 and L2 may not be points but may be areas with a finite extent. That is, the area illuminated by the light of the first wavelength L1 and the light of the second wavelength L2 may have an extent. When the illumination field F has an extent like this, imaging of the object P is possible over a wide band in terms of spatial frequency. That is, the optical device 14 is capable of wide, global imaging of the object P. On the other hand, the area illuminated by the light of the first wavelength L1 and the light of the second wavelength L2 may be a narrow area that can be regarded as approximately a point. In this case, the optical device 14 is capable of high-resolution imaging of the object P.

[0052] Even when the areas illuminated by the light of the first wavelength L1 and the light of the second wavelength L2 are wide, the processing unit 50 can perform imaging with high resolution in the conveyance direction by using the difference between signals that are close in time among the time series of light reception signals received by the light receiving unit 40. In other words, the light receiving unit 40 acquires light reception signals at high speed, increasing the number of light reception signals that can be acquired per unit time, and the processing unit 50 calculates the difference between them, thereby enabling the processing unit 50 to improve the imaging resolution in the conveyance direction.

[0053] (Second embodiment) The optical inspection system 10 according to this embodiment will be described below with reference to Fig. 5. This embodiment is a further modification of the first embodiment including various modifications, and the same components as those described in the first embodiment or components having the same functions are assigned the same reference numerals as much as possible, and detailed descriptions thereof will be omitted.

[0054] 5 shows a schematic perspective view of the optical inspection system 10 according to this embodiment. Following FIG. 1, an xyz Cartesian coordinate system is used as shown in FIG.

[0055] The light receiving section 40 of the optical device 14 of this embodiment includes a first light receiving element 42 and a second light receiving element 44, that is, two light receiving elements 42, 44. These light receiving elements 42, 44 are arranged at different spatial positions.

[0056] Each of the light receiving elements 42, 44 receives light of the first wavelength L1 and light of the second wavelength L2 and can distinguish between them. In other words, the light receiving elements 42, 44 can separate light of the first wavelength L1 and light of the second wavelength L2. The first light receiving element 42 and the second light receiving element 44 may be any element that can distinguish between and receive light of the first wavelength L1 and light of the second wavelength L2 and convert each into an independent light receiving signal.

[0057] Similar to the relationship described in the first embodiment, the line segment connecting the first illumination point P1 of the light of the first wavelength L1 illuminated by the illumination unit 30 and the second illumination point P2 of the light of the second wavelength L2 intersects with a line along the conveying direction of the conveying unit 12a of the conveying device 12. In other words, the line segment connecting the first illumination point P1 and the second illumination point P2 is not parallel to the line along the conveying direction of the conveying unit 12a of the conveying device 12. In other words, the angle θ between the line segment connecting the two illumination points P1 and P2 and the line along the conveying direction is greater than 0° and less than 180°. In particular, in this embodiment, the angle θ between the line segment connecting the two illumination points P1 and P2 and the line along the conveying direction is 90°, so that they are orthogonal to each other. The longitudinal direction of the irradiation field F is aligned with the line (y-axis) connecting the two illumination points P1 and P2. This maximizes the area through which the irradiation field F passes over the object P during conveyance. On the other hand, the more the longitudinal direction of the irradiation field F is aligned with the transport direction, the smaller the area through which the irradiation field F passes through the object P during transport. In other words, by orthogonally orthogonalizing the longitudinal direction of the irradiation field F to the transport direction, the area of ​​the irradiation field F that passes through the object P can be increased. In other words, this has the effect of increasing the range that can be imaged using the optical device 14.

[0058] That is, when the distance between the illumination points P1 and P2 is the same, by arranging the line segment connecting the illumination points P1 and P2 so that it is perpendicular to the conveying direction, a larger area in the width direction of the conveying section 12a can be inspected. For example, assuming that the object P is the same, when the illumination points P1 and P2 are arranged as shown in Fig. 5, a larger range of the object P can be scanned and imaged than when the illumination points P1 and P2 are arranged as shown in Fig. 1.

[0059] The operation of the optical inspection system 10 according to the embodiment described above will be described. In this embodiment and the following embodiments, the processing unit 50 performs processing according to the flow shown in FIG. 3. The contents described in the first embodiment will be omitted as appropriate. This also applies to the following embodiments.

[0060] The light source 32 of the illumination unit 30 irradiates light toward the conveyance unit 12a of the conveyance device 12. The illumination unit 30 irradiates light so that the first illumination point P1 and the second illumination point P2 are different points. The light that passes through (is reflected in this embodiment) the first illumination point P1 and the second illumination point P2 is received by the first light receiving element 42 and acquired as independent light receiving signals for each wavelength. Similarly, the light that passes through (is reflected in this embodiment) the first illumination point P1 and the second illumination point P2 is received by the second light receiving element 44 and acquired as independent light receiving signals for each wavelength.

[0061] These received light intensities are indices that represent the magnitude of the reflectance at the first illumination point P1 and the second illumination point P2, respectively. In other words, if the reflectance at each illumination point P1, P2 is high, the received light intensity will also be high accordingly. However, if the object P is transparent, the received light intensity will be transmittance instead of reflectance. Reflectance and transmittance are important characteristics of the object P, and acquiring their distribution on the object P, or the distribution of these indices, is called imaging. As described above, imaging at the first illumination point P1 and the second illumination point P2 is possible.

[0062] In this embodiment, the longitudinal direction of the irradiation field F is aligned with the line connecting the two illumination points P1 and P2. This maximizes the area through which the irradiation field F passes over the object P during transport. On the other hand, the more the longitudinal direction of the irradiation field F is aligned with the transport direction, the smaller the area through which the irradiation field F passes over the object P during transport. In other words, as in the optical inspection system 10 according to this embodiment, by orthogonally ...

[0063] In the optical device 14 of this embodiment, the first light receiving element 42 and the second light receiving element 44 can receive light reflected in two different directions from the first illumination point P1. Similarly, the first light receiving element 42 and the second light receiving element 44 can receive light reflected in two different directions from the second illumination point P2. The optical device 14 grasps the relative positional relationship (position, posture, and orientation) between the illumination unit 30 and the first light receiving element 42 and the second light receiving element 44 of the light receiving unit 40. It is known that the BRDF from each point on the object P (e.g., the first illumination point P1, the second illumination point P2) reflects physical property information of the object P. The processing unit 50 can acquire more detailed physical property information by acquiring the reflection angle dependency of the BRDF. In this embodiment, the dependency of the BRDF on two different reflection angles can be acquired at the first illumination point P1. Similarly, at the second illumination point P2, the dependence of the BRDF on two different reflection angles can be obtained, which has the effect of enabling more detailed physical property information of the object P to be obtained.

[0064] For example, suppose the first illumination point P1 is a glossy surface and the second illumination point P2 is a rough surface. That is, the first illumination point P1 reflects light with a narrow angular distribution, while the second illumination point P2 reflects light with a wide angular distribution. In this case, light of the second wavelength L2 is received by both the first light receiving element 42 and the second light receiving element 44, and light of the first wavelength L1 is received only by the first light receiving element 42. In other words, this embodiment has the advantage of being able to distinguish whether each of the illumination points P1 and P2 is a glossy surface or a rough surface.

[0065] According to this embodiment, an optical device 14, an optical inspection system 10, an imaging method for an object P, and an imaging program for an object P can be provided that can image a relatively moving object P not only from a direct facing position but also from an oblique position.

[0066] (Variation 1) Following FIG. 1, an xyz Cartesian coordinate system is taken as shown in FIG.

[0067] Although the light receiving unit 40 of the optical device 14 of this embodiment uses only the first light receiving element 42 and the second light receiving element 44, as shown in FIG. 6, multiple more light receiving elements 46 may be used with different spatial arrangements. These light receiving elements 42, 44, and 46 are arranged at different spatial positions. The directions of the line segments connecting the first light receiving element 42 and the second light receiving element 44, and the first light receiving element 42 and the third light receiving element 46, respectively, are different from each other. In this case, the angular distribution of the BRDF corresponding to the wavelength at each of the illumination points P1 and P2 and at an appropriate point between the illumination points P1 and P2 can be obtained in more detail. This has the effect of obtaining more detailed information about the object P. According to this embodiment, even if the BRDF of a microdefect is anisotropic and the BRDF of the microdefect changes angle only within a certain cross section relative to the standard plane, the directions of the line segments connecting the first light receiving element 42 and the second light receiving element 44, and the first light receiving element 42 and the third light receiving element 46 are different from each other, so the change in BRDF caused by the presence or absence of the microdefect can always be detected.

[0068] As an example, the third light receiving element 46 can be disposed immediately above the line segment connecting the illumination points P1 and P2, downstream of the first light receiving element 42 along the transport direction (x-axis direction).

[0069] (Variation 2) The optical device 14 according to the second modification of this embodiment will be described below with reference to FIG.

[0070] Fig. 7 shows a schematic cross-sectional view of the optical inspection system 10 according to the present modified example 2, as seen from the downstream side of the irradiation field F. Following Fig. 1, an xyz Cartesian coordinate system is used as shown in Fig. 7. The cross-sectional view shown in Fig. 7 is perpendicular to the conveying direction of the conveying unit 12a.

[0071] The optical device 14 according to this modification includes an illumination unit 30, a light receiving unit 40, and a beam splitter 60. Although details of the illumination unit 30 in Fig. 7 are omitted, it is assumed that the illumination unit 30 can emit light of a first wavelength L1 and a second wavelength L2 as parallel light toward the beam splitter 60.

[0072] The illumination unit 30 emits light (or light rays) of a first wavelength L1 and a second wavelength L2. The light L1 and L2 emitted from the illumination unit 30 are reflected by the beam splitter 60 and reach the object P. The points on the object P where the light of the first wavelength L1 and the light of the second wavelength L2 reach are referred to as a first illumination point P1 and a second illumination point P2, respectively. In this modification, the light source 32 of the illumination unit 30 emits a group of parallel light rays. Therefore, the light of the first wavelength L1 and the light of the second wavelength L2 are parallel to each other.

[0073] The first light receiving element 42 and the second light receiving element 44 of the light receiving unit 40 may be any element that can distinguish between and receive light of the first wavelength L1 and the second wavelength L2, and convert each into an independent light receiving signal, similar to the first light receiving element 42 described in the first embodiment.

[0074] The light receiving unit 40 further includes an imaging optical element 48. The imaging optical element 48 is, for example, an imaging lens. In FIG. 7, the imaging lens is schematically depicted as a single lens, but it may also be a lens assembly consisting of multiple lenses. Alternatively, the imaging optical element 48 may be a concave mirror, a convex mirror, or a combination thereof. In other words, the imaging optical element 48 may be any optical element that has the function of collecting a group of light rays emanating from a point on the object P, i.e., an object point, at a conjugate image point. The process of collecting (concentrating) a group of light rays emanating from an object point on the surface of the object P at an image point by the imaging optical element 48 is called imaging. Alternatively, it may be called transferring the object point to the image point (a conjugate point of the object point). The plane of conjugate points to which a group of light rays emanating from a sufficiently distant object point are transferred by the imaging optical element 48 is called the focal plane f of the imaging optical element 48. Furthermore, a line perpendicular to the focal plane f and passing through the center of the imaging optical element 48 is defined as the optical axis C. In this case, an image point on the optical axis C that is conjugate with an object point that is sufficiently far away is called a focus. In this embodiment, the imaging optical element 48 may be simply called a lens.

[0075] The first light receiving element 42 and the second light receiving element 44 are each disposed on the focal plane f of the imaging optical element 48. In this modification, the first light receiving element 42 is disposed on the optical axis C, directly above the line segment connecting the first illumination point P1 and the second illumination point P2.

[0076] The line segment connecting the first illumination point P1 and the second illumination point P2 is perpendicular to a line extending along the conveying direction of the conveying section 12a of the conveying device 12. In other words, the line segment connecting the first illumination point P1 and the second illumination point P2 is not parallel to the line extending along the conveying direction of the conveying section 12a of the conveying device 12. In other words, the angle θ between the line segment connecting the two illumination points P1 and P2 and the line extending along the conveying direction is greater than 0° and less than 180°. In particular, in this embodiment, the angle θ between the line segment connecting the two illumination points P1 and P2 and the line extending along the conveying direction is 90°. The longitudinal direction of the irradiation field F is aligned with the line connecting the two illumination points P1 and P2. This maximizes the area through which the irradiation field F passes over the object P during conveyance. On the other hand, the more the longitudinal direction of the irradiation field F is aligned with the conveying direction, the smaller the area through which the irradiation field passes over the object P during conveyance. That is, by orthogonally ...

[0077] The operation of the optical inspection system 10 according to this modified example will now be described.

[0078] The processing unit 50 controls the illumination unit 30 to irradiate light toward the conveying unit 12a of the conveying device 12 via the beam splitter 60. The area illuminated by the light from the light source 32 of the illumination unit 30 is called the illumination field F. The object P being conveyed by the conveying unit 12a of the conveying device 12 is illuminated by the light from the light source 32 of the illumination unit 30. Light of a first wavelength L1 and a second wavelength L2 is emitted from the light source 32 of the illumination unit 30 and is reflected by or transmitted through the surface of the object P.

[0079] The point where light of the first wavelength L1 reaches the object P is called the first illumination point P1, and the point where light of the second wavelength L2 reaches the object P is called the second illumination point P2. The light source 32 of the illumination unit 30 emits light so that the first illumination point P1 and the second illumination point P2 are different points. The light passing through (or reflected in this modification) the first illumination point P1 and the second illumination point P2 is received by the first light-receiving element 42 and acquired as independent light-receiving signals for each wavelength L1 and L2. The received light intensities are indices representing the magnitude of the reflectance at the first illumination point P1 and the second illumination point P2, respectively. In other words, the higher the reflectance at each illumination point P1 or P2, the higher the received light intensity. Reflectance is an important characteristic of the object P, and acquiring its distribution on the object P, or the distribution of these indices, is called imaging. As described above, the processing unit 50 can perform imaging at the first illumination point P1 and the second illumination point P2 using the first light receiving element 42. Similarly, light that passes through (or is reflected in this modification) the first illumination point P1 and the second illumination point P2 is received by the second light receiving element 44 and acquired as independent light receiving signals for each of the wavelengths L1 and L2. Then, the processing unit 50 can perform imaging at the first illumination point P1 and the second illumination point P2 using the second light receiving element 44.

[0080] According to this modification, light from the first illumination point P1 in two different reflection directions can be received by the first light receiving element 42 and the second light receiving element 44. Similarly, light from the second illumination point P2 in two different reflection directions, the same as that obtained at the first illumination point P1, can be received by the first light receiving element 42 and the second light receiving element 44. It is known that the BRDF from each point P1, P2 of the object P reflects the physical property information of the object P. Then, by obtaining the reflection angle dependency of the BRDF, more detailed physical property information can be obtained. According to this modification, the light intensities for two reflection angles of the BRDFs from the first illumination point P1 and the second illumination point P2 can be obtained simultaneously. Then, these BRDFs can be compared. This has the effect of obtaining more detailed physical property information of the object P.

[0081] For example, suppose that the object P is a flat, smooth, glossy surface. There is no defect at the first illumination point P1, but there is a defect at the second illumination point P2. The BRDF of a glossy surface generally exhibits specular reflection. The angular distribution of the BRDF at a defect point is generally broad. Therefore, specular reflection occurs at the first illumination point P1, and the light is incident on the first light-receiving element 42. Meanwhile, reflection with a wide angular distribution occurs at the second illumination point P2, and the reflected light is received by both the first light-receiving element 42 and the second light-receiving element 44. In this case, the light of the second wavelength L2 is received by both the first light-receiving element 42 and the second light-receiving element 44, while the light of the first wavelength L1 is received only by the first light-receiving element 42. Alternatively, the received intensity of the light of the first wavelength L1 received by the second light-receiving element 44 is significantly smaller than the received intensity of the light of the second wavelength L2. That is, this modification has the effect of enabling the processing unit 50 to detect the presence of a defect at the second illumination point P2 by acquiring the reception intensities of the wavelengths L1 and L2 of the first light receiving element 42 and the second light receiving element 44. Therefore, by acquiring the reception intensities of the wavelengths L1 and L2 of the first light receiving element 42 and the second light receiving element 44, the processing unit 50 can acquire object information of the object P at the first illumination point P1.

[0082] 7, the parallel light from the light source 32 of the illumination unit 30 is depicted as being irradiated perpendicularly onto the object P by the beam splitter 60. In other words, the parallel light is depicted as being irradiated perpendicularly onto the plane of the object P. For example, the parallel light from the light source 32 of the illumination unit 30 may be irradiated obliquely onto the object P by the beam splitter 60 along the conveying direction from downstream to upstream or from upstream to downstream, and the light reflected from the object P may be received by the light receiving unit 40 having an imaging lens 48.

[0083] According to this modification, the processing unit 50 performs imaging based on the light receiving signal from the light receiving unit 40. In this case, there is an advantage that the object P, which is a planar subject, can be imaged not only directly above (directly facing) but also from an oblique angle. In this modification, the first light receiving element 42 and the second light receiving element 44 are used, so there is an advantage that the processing unit 50 can simultaneously perform imaging from two different angular directions.

[0084] (Third embodiment) The optical inspection system 10 according to this embodiment will be described below with reference to FIGS.

[0085] 8 shows a schematic perspective view of the optical inspection system 10 according to this embodiment. Following FIG. 1, an xyz Cartesian coordinate system is used as shown in FIG.

[0086] 9 shows a schematic top view of the first wavelength L1 and the second wavelength L2 from the light source 32 of the illumination unit 30 of the optical inspection system 10 according to this embodiment, and the object P being transported on the transport unit 12a of the transport device 12. The top view shown in FIG. 9 is a plane parallel to the transport direction. In the example shown in FIG. 9, the object P indicates the position immediately before the pattern light Pa is illuminated on the object P. Following FIG. 8, an xyz Cartesian coordinate system is taken as shown in FIG.

[0087] Fig. 10 is a schematic diagram showing the state in which the object P is illuminated with pattern light after an appropriate amount of time has passed since the state shown in Fig. 9. The top view shown in Fig. 10 is a plane parallel to the conveying direction. Following Fig. 8 and Fig. 9, an xyz Cartesian coordinate system is taken as shown in Fig. 10.

[0088] As shown in FIG. 8, the light receiving section 40 of this embodiment includes a first light receiving element 42.

[0089] The light source 32 of the illumination unit 30 includes, for example, a color projector (projection device). The color projector may be a DLP (Digital Light Processing) type with a DMD (Digital Mirror Device), an LCD (Liquid Crystal Display) type with an LCD (Liquid Crystal on Silicon) type, or the like. The light source 32 of the illumination unit 30 may be an LED or a laser. Light of a first wavelength L1 and light of a second wavelength L2 are emitted from the light source 32 of the illumination unit 30, and a projection pattern Pa is formed by each of the lights.

[0090] As shown in Figures 8 to 10, the optical device 14 forms a first projection pattern Pa1 with M x N projection element numbers using light of a first wavelength L1 from the light source 32 of the illumination unit 30. As shown in Figures 9 and 10, the number of projection element numbers in the transport direction is M, and the number of projection element numbers in the direction perpendicular to the transport direction is N. The aspect ratio (pixel size of the projected image) of each projection element projected by the light source (projection device) 32 of the illumination unit 30 is assumed to be smaller in the transport direction than in the direction perpendicular to the transport direction. This is referred to as the first projection pattern Pa1. The first projection pattern Pa1 may be any pattern, but here it is assumed to be a random pattern.

[0091] Similarly, the optical device 14 forms a second projection pattern Pa2 with M×N projection pixel numbers using light of a second wavelength L2 from the light source 32 of the illumination unit 30. This is referred to as the second projection pattern Pa2. The aspect ratio (pixel size of the projected image) of each projection pixel projected by the light source (projection device) 32 of the illumination unit 30 is assumed to be smaller in the transport direction than in the direction perpendicular to the transport direction. The second projection pattern Pa2 may be any pattern, but here it is assumed to be a random pattern. M and N are integers, and M is greater than or equal to N (M≧N). In this embodiment, M and N are assumed to be the same (equal).

[0092] 9 and 10, the processing unit 50 acquires light reception signals of the light of the first wavelength L1 and the second wavelength L2 each time the object P is conveyed in the conveying direction by a distance equal to the projection pixel size (1 / M) by the conveying unit 12a of the conveying device 12 and the first light receiving element 42 of the light receiving unit 40. In particular, the light reception signal of the light of the first wavelength L1 is designated as B (blue light).

[0093] It is assumed that the area of ​​the object P passing through the first projection pattern Pa1 as it is transported by the transport unit 12a can be imaged with N pixels in a direction perpendicular to the transport direction. It is also assumed that it can be imaged with pixels of the same size in the transport direction. In other words, it is assumed that the object P is composed of uniform cell areas. It is also assumed that one side of each cell is equal to the pixel size of the projection pattern Pa1 in a direction perpendicular to the transport direction.

[0094] The illumination unit 30 uses a projection device as the light source 32, and can emit light of the first wavelength L1 and light of the second wavelength L2 at different irradiation positions.

[0095] The operation of the optical inspection system 10 according to the embodiment described above will now be described.

[0096] A top view of this embodiment is shown in Fig. 10. Fig. 10 shows a state after a little time has passed since Fig. 9, when the object P has been conveyed in the conveying direction.

[0097] The first projection pattern Pa1 using light of the first wavelength L1 has a total number of projection elements M × N. Here, the value of each projection element is I, the number of the transport direction is i, and the number of the direction perpendicular to that is j, resulting in Iij. In other words, Iij is the light receiving intensity obtained by the first light receiving element 40 of the light receiving unit 40 when the first projection pattern Pa1 using light of the first wavelength L1 is projected onto the object P.

[0098] Furthermore, among the pixels of the object P passing through the first projection pattern Pa1, the one in the upper row in FIG. 9 is designated R, and the number i in the transport direction is added to designate Ri. Similarly, the one in the lower row in FIG. 9 is designated ri. The light receiving signal from the first light receiving element 42 when the pixel ri in the lower row of the object P reaches the first row (1 / Mth row) of the first projection pattern Pa1 is designated B1. Similarly, the light receiving signal from the first light receiving element 42 when the pixel ri in the lower row of the object P reaches the ith row (i / Mth row) of the first projection pattern Pa1 is designated Bi. Note that M is equal to or greater than N. In this case, the following equations hold for i=1 to N, respectively.

[0099]

number

[0100] This equation (1) can be regarded as a set of N simultaneous equations. On the other hand, if the pixel Ri of the object P in the upper row in FIG. 9 is known, the unknown parameter is ri, and the number of unknowns becomes N. Therefore, a solution can be found by solving equation (1) as a set of simultaneous equations. Then, as the object P is transported, by inductively using equation (1), it is possible to obtain the pixel values ​​of the object P passing through the projection pattern Pa formed by light of the first wavelength L1. In other words, there is an effect that it becomes possible to image the object P passing through the area of ​​the first projection pattern Pa1.

[0101] That is, when pixels (reflectances) R1, ..., RN of the object P pass through the projection pixel values ​​I11, ..., I1N to IN1, ..., INN of the first projection pattern Pa1, the processing unit 50 first determines the reference reflectances R1, ..., RN based on the light reception signals from the first light receiving elements 42 of the light receiving unit 40. Then, when pixels (reflectances) r1, ..., rN of the object P pass through the projection pixel values ​​I11, ..., I1N to IN1, ..., INN of the first projection pattern Pa1, the processing unit 50 determines the reflectances r1, ..., rN of the second row of the object P based on the light reception signals from the first light receiving elements 42 of the light receiving unit 40 and the reference reflectances R1, ..., RN. That is, when the first projection pattern Pa1 is projected onto the object P, the reflectance of the second row of the object P is determined using the reflectance of the first row of the object P. Similarly, the processing unit 50 inductively determines the reflectances of the remaining pixels (reflectances) of the object P.

[0102] That is, when the object P passes under the first projection pattern Pa, the processing unit 50 acquires the light receiving signal in increments of 1 / M, and thereafter, by inductive calculation, can obtain the pixel value of each pixel of the object P. Therefore, the processing unit 50 can perform imaging of the object P based on the pixel value of each pixel of the object P.

[0103] The same is true for the second projection pattern Pa2 formed with light of the second wavelength L2. The light of the first wavelength L1 and the light of the second wavelength L2 can be simultaneously and independently acquired by the first light receiving element 42. This has the effect of enabling imaging of the object P being transported across the entire projection area of ​​the illumination unit 30. In other words, by simultaneously using light of the second wavelength L2, it is possible to image a wider range than by using only the first wavelength L1. For example, by using the third wavelength L3, it is possible to reduce the projection pixel size of the projection pattern Pa in the direction (N) perpendicular to the transport direction, allowing for more detailed imaging.

[0104] The pixel size of the projection pattern Pa is smaller in the transport direction (M) than in the direction perpendicular to it (N). This has the effect of making it possible to image the object P that has passed through the projection pattern Pa using equation (1) even over a short transport distance.

[0105] According to this embodiment, an optical device 14, an optical inspection system 10, an imaging method for an object P, and an imaging program for an object P can be provided that can image a relatively moving object P not only from a direct facing position but also from an oblique position.

[0106] (Variation) 11, the projection pattern Pa by the light source 32 of the illumination unit 30 may be condensed using a cylindrical lens 38 to reduce the irradiation field size (M) in one direction (for example, the conveying direction). This has the effect of enabling imaging of the object P that has passed through the projection pattern Pa using equation (1) even over a short conveying distance.

[0107] According to at least one of the embodiments described above, it is possible to provide an optical device 14, an optical inspection system 10, an imaging method for an object P, and an imaging program for an object P that can image a relatively moving object P not only from a direct facing position but also from an oblique position.

[0108] 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]

[0109] 10...optical inspection system, 12...conveying device, 12a...conveying section, 14...optical device, 30...illuminating section, 32...light source, 33...diaphragm, 34...diffraction grating, 35...illumination lens, 38...cylindrical lens, 40...light receiving section, 42...first light receiving element, 44...second light receiving element, 48...imaging optical element, 50...processing section, 60...beam splitter, L1...first wavelength, L2...second wavelength, P1...first illumination point, P2...second illumination point.

Claims

1. an illumination unit that illuminates light onto an object that moves relatively in a predetermined direction; the illumination unit is configured to illuminate a first illumination point on the object with light of a first wavelength, and to illuminate a second illumination point on the object that is different from the first illumination point with light of a second wavelength that is different from the first wavelength; a line segment connecting the first illumination point and the second illumination point intersects with the predetermined direction; A lighting section, a light receiving unit that moves relative to the object while maintaining a positional relationship with the illumination unit, and that includes a first light receiving element that receives light that has passed through the first illumination point on the object and light that has passed through the second illumination point; the first light receiving element can distinguish between the first wavelength and the second wavelength and independently receive the light; A light receiving unit; a processing unit that performs imaging of the object based on a light receiving signal obtained by receiving light that has passed through the first illumination point and the second illumination point; Equipped with optical equipment.

2. The light receiving unit further includes a second light receiving element disposed at a different spatial position from the first light receiving element, the second light receiving element can distinguish between the first wavelength and the second wavelength and independently receive the light, the processing unit acquires object information at the first illumination point on the object based on signals received by the first light receiving element and the second light receiving element.

10. The optical device of claim 1.

3. The object is provided with an imaging optical element that transmits light therethrough, At least the first light receiving element is disposed on a focal plane of the imaging optical element.

3. The optical device according to claim 2.

4. the second light receiving element is further disposed on the focal plane of the imaging optical element; 4. The optical device according to claim 3.

5. the light receiving unit further includes a third light receiving element disposed at a different spatial position from the first light receiving element and the second light receiving element, the directions of the line segments connecting the first light receiving element and the second light receiving element and the line segments connecting the first light receiving element and the third light receiving element are different from each other; the third light receiving element can distinguish between the first wavelength and the second wavelength and independently receive the light, the processing unit acquires object information at the first illumination point on the object based on signals received by the first light receiving element, the second light receiving element, and the third light receiving element.

3. The optical device according to claim 2.

6. the illumination unit uses a diffraction grating to make the light of the first wavelength and the light of the second wavelength light at different irradiation positions.

3. The optical device according to claim 1.

7. the illumination unit uses a projection device to project the light of the first wavelength and the light of the second wavelength at different irradiation positions; 3. The optical device according to claim 1.

8. The pixel size of the projection image projected by the projection device is smaller in the predetermined direction than in a direction perpendicular to the predetermined direction, the processing unit performs imaging of the object based on the projected image and a signal obtained by the first light receiving element.

8. The optical device according to claim 7.

9. The illumination unit uses a cylindrical lens to condense light to an irradiation field size in one direction.

8. The optical device according to claim 7.

10. The optical device according to claim 1 or 2; a conveying device that conveys the object in the predetermined direction and includes a conveying unit that moves relatively to the illumination unit and the light receiving unit; An optical inspection system comprising:

11. maintaining a relative position of an optical device having an illumination unit and a light receiving unit, and moving an object in a predetermined direction relative to the illumination unit and the light receiving unit, while illuminating a first illumination point on the object with light of a first wavelength from the illumination unit, and illuminating a second illumination point on the object different from the first illumination point with light of a second wavelength different from the first wavelength; receiving the light that has passed through the first illumination point on the object and the light that has passed through the second illumination point with the light receiving unit that includes a first light receiving element that can distinguish between the first wavelength and the second wavelength and receive the light independently; imaging the object based on a light receiving signal of the light received by the light receiving unit and having passed through the first illumination point and the second illumination point; Equipped with a line segment connecting the first illumination point and the second illumination point intersects with the predetermined direction; Methods for imaging objects.

12. a light source for illuminating a first illumination point on the object with light of a first wavelength from the illumination unit, and a light source for illuminating a second illumination point on the object that is different from the first illumination point with light of a second wavelength that is different from the first wavelength, while maintaining a relative position of an optical device having an illumination unit and a light receiving unit and moving the object in a predetermined direction relative to the illumination unit and the light receiving unit, wherein a line segment connecting the first illumination point and the second illumination point intersects with the predetermined direction; receiving the light that has passed through the first illumination point on the object and the light that has passed through the second illumination point by the light receiving unit that includes a first light receiving element that can distinguish between the first wavelength and the second wavelength and receive the light independently; imaging the object based on a light receiving signal of the light received by the light receiving unit and having passed through the first illumination point and the second illumination point; to the computer, Object imaging program.

Images