Optical inspection device, optical inspection method and optical inspection program

Abstract

To provide an optical inspection device capable of suppressing false detection of a singular part such as defects.SOLUTION: According to an embodiment, an optical inspection device includes a control unit. The control unit projects first modulation pattern light having an intensity modulation pattern in which the modulation direction is approximately parallel to the direction of an end of an object onto objects, captures images of the objects onto which the first modulation pattern light has been projected to acquire a first image group, and generates a first singular light scattering image that may include an image of a singular region that is located in a region on the end of the object or inside the end, extracted on the basis of the first image group, and scatters light in a singular manner with the first modulation pattern light through singular scattering extraction processing.SELECTED DRAWING: Figure 5A

Description

[Technical field]

[0001] An embodiment of the present invention relates to an optical inspection device, an optical inspection method, and an optical inspection program. [Background technology]

[0002] In various industries, non-contact optical inspection of objects is becoming important. For example, pattern projection imaging is a method for non-contact optical inspection in which a pattern of light with spatial intensity modulation that can be expressed by a trigonometric function is projected onto an object in sequence, the object is imaged each time, and the characteristics of the object are obtained from the multiple images obtained by imaging. However, false signals may appear due to the effect of light reflection from the edge of the object. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] DJ Cuccia, et. al., “Quantitation and mapping of tissue optical properties using modulated imaging,” Journal of Biomedical Optics 14(2), (2009). Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide an optical inspection device, an optical inspection method, and an optical inspection program that can suppress erroneous detection of unique areas such as defects. [Means for solving the problem]

[0005] According to an embodiment, the optical inspection device includes a control unit that projects a first modulated pattern light having an intensity modulation pattern whose modulation direction is substantially parallel to the direction of the end of the object onto each object, captures an image of each object onto which the first modulated pattern light is projected to obtain a first group of images, and generates a first peculiar light scattering image by a peculiar scattering extraction process, the first peculiar light scattering image being located at the end of the object or in a region inside the end, being extracted based on the first group of images, and may include an image of a peculiar region that scatters light peculiarly due to the first modulated pattern light. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram showing the configuration of an example optical inspection device according to a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of a hardware configuration of a control device. [Figure 3A] A diagram showing four overlapping pattern lights with a phase shift of λ / 4 projected onto the projection surface of an object. [Figure 3B] 3B is a diagram showing an example of light on an object surface in response to the projection of the four pattern lights shown in FIG. 3A. [Figure 3C] 3B according to the projection of the pattern light of FIG. 3A; FIG. [Figure 4] FIG. 1 is a schematic perspective view showing an example of an object to be optically inspected by the optical inspection device of the first embodiment. [Figure 5A] 4B is a diagram showing a scattered image (first differential light scattered image) in a case where the modulation direction of the pattern light is approximately parallel to the direction in which the end of the object extends, at a position including the end indicated by the symbol V in FIG. 4A. FIG. [Figure 5B] 4B is a diagram showing a scattering image (second specific light scattering image) in which the modulation direction of the pattern light is non-parallel to the direction in which the end of the object extends, at a position including the end indicated by symbol V in FIG. 4A. FIG. [Figure 6] An example of a peculiar light scattering image when there is a peculiar area (defect) on or near the edge of an object. [Figure 7] 5 is a flowchart showing a process according to an optical inspection program performed by the optical inspection device according to the first embodiment. [Figure 8] 8 is a flowchart showing a subroutine of step S11 shown in FIG. 7. [Figure 9] 5 is a flowchart showing a process according to an optical inspection program performed by the optical inspection device according to the first embodiment. [Figure 10] 1 is a schematic diagram showing an object that can be inspected by an optical inspection device according to a first modified example of the first embodiment, a pattern light used when inspecting the object, and a modulation direction of the pattern light. FIG. [Figure 11] FIG. 13 is a diagram showing a configuration of an example of an optical inspection device according to a second modified example of the first embodiment. [Figure 12] 10 is a flowchart showing a process according to an optical inspection program performed by an optical inspection device according to a second modified example of the first embodiment. [Figure 13A] A figure showing the area indicated by symbol V in Figure 4 of a peculiar light scattering image generated using pattern light (second modulated pattern light) that is non-parallel to the direction in which the end of the object extends, and also showing a schematic diagram of the inspection target area in the peculiar light scattering image. [Figure 13B] A figure showing the area indicated by symbol V in Figure 4 of a peculiar light scattering image generated using pattern light (second modulated pattern light) that is non-parallel to the direction in which the end of the object extends, and also showing a schematic diagram of the inspection target area in the peculiar light scattering image. [Figure 14A] FIG. 1 is a schematic diagram showing an example of the setting range of the inspection target area when inspecting an object having a parallelogram outer shape (end) using pattern light whose modulation direction is parallel to the direction in which the upper or lower end extends. [Figure 14B] FIG. 1 is a schematic diagram showing an example of the setting range of the inspection target area when inspecting an object having a parallelogram outer shape (end) using pattern light whose modulation direction is parallel to the direction in which the left or right end extends. [Figure 15] 8 is a flowchart showing a subroutine of step S11 shown in FIG. 7, regarding processing based on an optical inspection program performed by an optical inspection device according to a second embodiment. [Figure 16]13 is a schematic diagram showing an object that can be inspected by an optical inspection device according to a modified example of the second embodiment, a pattern light used when inspecting the object, a modulation direction of the pattern light, and an inspection target range. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, the embodiments will be described with reference to the drawings. The drawings are schematic or conceptual. The relationship between the thickness and width of each part, the size ratio between parts, etc., shown in the drawings are not necessarily the same as the actual ones. Even when the same part is shown, the dimensions and ratios of each part may be different depending on the drawing. In this specification and each drawing, elements similar to those described above with respect to the previous drawings are given the same reference numerals, and detailed descriptions are omitted as appropriate.

[0008] Furthermore, the term "light" used in the following description is a type of electromagnetic wave, and includes gamma rays, X-rays, ultraviolet rays, visible light, infrared rays, radio waves, and the like. In the following description, light will be described as visible light. Visible light belongs to a wavelength range of, for example, 400 nm to 750 nm. Meanwhile, when light is mentioned in the following description, it may be replaced with gamma rays, X-rays, ultraviolet rays, visible light, infrared rays, radio waves, and the like.

[0009] (First embodiment) The first embodiment will be described with reference to Fig. 1 to Fig. 9. Fig. 1 is a diagram showing a configuration of an example optical inspection device 1 according to the first embodiment. The optical inspection device 1 of the first embodiment has a projector 10, an imaging device 20, and a control device 30.

[0010] The projector 10 projects modulated pattern light (hereinafter, mainly referred to as pattern light) having a spatial intensity modulation pattern onto the object O. The pattern light in this embodiment is light in which light and dark change periodically on the object O. Here, the periodic change in light and dark corresponds to a change in intensity such that a region with high intensity and a region with low intensity are periodically located. However, periodic does not necessarily mean only a pattern that is repeated at a constant interval. That is, the period may vary. In other words, periodic corresponds to a region with high intensity and a region with low intensity being repeatedly located. In the following, for the sake of simplicity, unless otherwise specified, periodic refers to a pattern having a constant period. In addition, as will be described in detail later, in the first embodiment, the projector 10 is configured to be able to project pattern light in two modulation modes corresponding to two different spatial intensity modulation patterns. In the following description, the term "projection" may be used in the same sense as the term "projection".

[0011] Here, the object O is assumed to be, for example, transparent to visible light and composed of a uniform scattering medium. The material, shape, and thickness of the object O are not particularly limited. In the following, the object O in this embodiment is assumed to be a plate having a thickness of about several millimeters and having light transparency. In addition, the description will be continued assuming that the surface onto which the pattern light is projected, of the two surfaces facing each other in the thickness direction of the plate-like object O, is the back side, and the surface onto which the image is captured is the front side. In the example of FIG. 1, the pattern light is projected from the back side surface of the object O, passes through the object O while being scattered within the object O, reaches the front side surface of the object O, and is emitted from the object O. An image of the object O is captured with the light emitted from the object O. The surface of the object O onto which the pattern light is projected is generally called the projection surface Pp, and the surface onto which the image is captured is called the object surface Po. That is, in the example of FIG. 1, the projection surface Pp is the back side surface of the object O, and the object surface Po is the front side surface of the object O.

[0012] In this embodiment, an XYZ Cartesian coordinate system is taken for the optical inspection device 1 as shown in FIG. 1. The object O is a substantially rectangular plate, and the projection plane Pp and the object plane Po are arranged parallel or nearly parallel to a plane formed by the X-axis and the Y-axis. The projection plane Pp and the object plane Po of the object O are also assumed to be perpendicular to the Z-axis. A pair of ends (edges) E1a, E2a (see FIG. 4) of the object O are also assumed to be parallel to the X-axis, and the remaining pair of ends (edges) E1b, E2b (see FIG. 4) of the object O are also assumed to be parallel to the Y-axis. Here, the ends E1a, E2a parallel to the X-axis will be mainly described.

[0013] Furthermore, in the first embodiment, the object O may have a peculiar region S. The peculiar region S is a localized region inside or on the surface of the object O that is composed of a peculiar medium or a peculiar shape. The peculiar medium or peculiar shape may be, for example, a foreign object or bubble mixed into the object, a crack or breakage occurring in the object O, a region of peculiar density caused by stress strain of the object O, a minute uneven shape on the surface of the object O, or a surface of the object O whose surface roughness is different from that of the surroundings. However, the peculiar medium or peculiar shape is not limited to those listed here.

[0014] The projector 10 includes a light source 11 , a spatial modulator 12 , and projection optics 13 .

[0015] The light source 11 emits light. The light source 11 may be any light source such as a laser light source, an LD (Laser Diode) light source, an LED (Light Emitting Diode) light source, a filament light source, a halogen lamp, or a xenon lamp. For example, in the first embodiment, the description will be continued assuming that the light source 11 is a white LED light source. The wavelength spectrum of the white light has significant intensity in the wavelength range from 450 nm to 750 nm. Here, the light source 11 may be provided separately from the projector 10.

[0016] The spatial modulator 12 has a modulation surface. The modulation surface is composed of a collection of modulation pixels. The modulation surface changes the characteristics of light independently for each modulation pixel. The characteristics of light include, for example, intensity, polarization direction, wavelength spectrum, etc. The modulation surface may be, for example, a DMD (Digital Micromirror Device), an LCD (Liquid Crystal Display) panel, an LCOS (Liquid Crystal on Silicon) panel, etc. The shape of the modulation surface may be any shape. For example, the shape of the modulation surface may be an area shape or a line shape.

[0017] The projection optical element 13 has a projection optical axis zp, and images the pattern light obtained by the spatial modulation in the spatial modulator 12 onto the object O along the projection optical axis zp. As a result, a projected image corresponding to the modulation surface is formed on the object O. The projection optical element 13 is, for example, a lens. However, the projection optical element 13 may be anything that can image light emitted from an object point in space onto an image point. In the case of an optical system defined by the projection optical element 13, the object point is a point on the modulation surface of the spatial modulator 12, and the image point is a point on the projection surface Pp of the object O.

[0018] The imaging device 20 has an imaging optical element 21 and an image sensor 22. The imaging device 20 captures an image of the object O by using light emitted from an object surface Po of the object O.

[0019] The imaging optical element 21 has an imaging optical axis zi, and forms an image of light emitted from an object O on the image sensor 22. The imaging optical element 21 is, for example, a lens. The imaging optical element 21 may be anything that can form an image of light emitted from an object point in space onto an image point. In the case of an optical system defined by the imaging optical element 21, the object point is a point on the object surface Po of the object O, and the image point is a point on the pixel surface of the image sensor 22.

[0020] The image sensor 22 has a pixel surface. The pixel surface is composed of a collection of imaging pixels using photoelectric conversion elements. Each imaging pixel converts incident light into a pixel signal as an electrical signal. The collection of pixel values ​​based on the pixel signals forms an image. The image sensor 22 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The image sensor 22 may be any type of sensor capable of acquiring an image. The shape of the pixel surface may also be any type. The shape of the pixel surface may be an area shape or a line shape.

[0021] The control device 30 is a computer that controls the optical inspection device 1. The control device 30 controls the start / stop of irradiation of pattern light from the projector 10 and controls switching of modulation modes. The control device 30 also generates a first specific light scattering image as an inspection image from a plurality of images (first image group) obtained from the imaging device 20 by a specific scattering extraction process.

[0022] Fig. 2 is a diagram showing an example of a hardware configuration of the control device 30. As shown in Fig. 2, the control device 30 includes a computer to which a control unit 31, a storage unit 32, a power supply unit 33, a timing device 34, a communication interface (I / F) 35, an input unit 36, an output device 37, and an external interface (I / F) 38 are electrically connected. Here, the control device 30 may include elements other than those shown in Fig. 2, or may not include some of the elements shown in Fig. 2. For example, the control device 30 may not include the timing device 34.

[0023] The control unit 31 includes a processor such as a CPU (Central Processing Unit), a RAM (Random Access Memory), and / or a ROM (Read Only Memory), and controls each component of the control device 30. The control unit 31 can call up an execution program stored in the storage unit 32 and execute processing.

[0024] The storage unit 32 is a medium that stores information such as a program so that the information can be read by a computer or the like. The storage unit 32 may be, for example, an auxiliary storage device such as a hard disk drive or a solid state drive. Furthermore, the storage unit 32 may include a drive. A drive is a device for reading data stored in another auxiliary storage device, a recording medium, or the like, and includes, for example, a semiconductor memory drive (a flash memory drive), a CD (Compact Disk) drive, a DVD (Digital Versatile Disk) drive, and the like. The type of drive may be appropriately selected depending on the type of storage medium.

[0025] The power supply unit 33 supplies power to each element of the control device 30. The power supply unit 33 may include, for example, a secondary battery or an AC power supply.

[0026] The timing device 34 is a device that measures time. For example, the timing device 34 may be a clock including a calendar, and transmits information on the current year, month, and / or date to the control unit 31. The timing device 34 may be used to record the date and time of an examination, etc.

[0027] The communication interface 35 is, for example, a short-distance wireless communication (for example, Bluetooth (registered trademark)) module, a wired LAN (Local Area Network) module, a wireless LAN module, etc., and is an interface for performing wired or wireless communication via a network. The communication via this network may be either wireless or wired. The network may be an internetwork including the Internet, or may be another type of network such as an in-house LAN. Furthermore, the communication interface 35 may perform one-to-one communication using a USB (Universal Serial Bus) cable or the like. Furthermore, the communication interface 35 may include a micro USB connector. The communication interface 35 is an interface for connecting to an external device such as various communication devices. The communication interface 35 is controlled by the control unit 31, and sends various information to the external device via a network or the like. The various information is, for example, an inspection image of the object O.

[0028] The input unit 36 ​​is a device that accepts input, and may be, for example, a touch panel, a physical button, a mouse, a keyboard, etc. The output device 37 is a device that performs output, and may be, for example, a display that outputs information by display or the like.

[0029] The external interface 38 is for intermediating between the main body of the optical inspection device 1 and an external device. The external device may be, for example, a printer, a memory, a communication device, or the like.

[0030] The control unit 31 executes processes to exert various functions by having the processor execute programs and the like stored in the storage unit 32. It is preferable that the control program of the control unit 31 is not stored in the storage unit 32 of the control unit 31, but is placed on an appropriate server or cloud. In this case, the control program is executed while communicating with, for example, a processor of the optical inspection device 1 via the communication interface 35. The control unit 31 according to this embodiment may be disposed near the projector 10 or the imaging device 20, or may be located on a server or cloud of a system of various inspection sites away from the projector 10 or the imaging device 20. For this reason, it is preferable that the optical inspection program is not stored in the storage unit 32, but is on a server or cloud, and the program is executed while communicating with, for example, a processor of the optical inspection device 1 via the communication interface 35. Therefore, the control unit 31 (processor) can execute an optical inspection program (optical inspection algorithm) (see FIG. 7 to FIG. 9) described later.

[0031] Next, an optical inspection method using the optical inspection device 1 according to this embodiment will be described. Fig. 3A to Fig. 3C are schematic diagrams showing the optical inspection method of the first embodiment. In the optical inspection method of the first embodiment, pattern light having a spatial intensity modulation pattern is projected onto an object. Then, the object O is imaged by the light transmitted through the object, and an image is acquired based on pixel signals obtained by imaging. The pattern light is formed from, for example, white light.

[0032] In the first embodiment, a projector 10 irradiates an object O with a plurality of pattern lights having the same modulation direction at time intervals or over time. This causes the imaging device 20 to acquire a plurality of images corresponding to the respective pattern lights. Based on these images, the control device 30 acquires information regarding the peculiar region S of the object O.

[0033] Light incident on the peculiar region S exhibits scattering characteristics different from those of light incident on the uniform medium surrounding the peculiar region S. In other words, the light scattering distribution is different in the uniform medium and in the peculiar region. In other words, the peculiar region S is a localized region that exhibits light scattering characteristics different from those of a uniform medium. The peculiar region S can be any localized region that causes peculiar light scattering. For example, peculiar light scattering occurs in cracks, surface cracks and stains, and foreign objects within the object O. Therefore, the presence or absence of cracks in the object O is inspected by detecting the presence or absence of the peculiar region S of the object O.

[0034] FIG. 3A shows an example of each pattern light (one set of first modulated pattern light) projected on the projection surface Pp of the object O. The horizontal axis of FIG. 3A indicates the position of the projection surface Pp of the object O on a line segment on the paper surface of FIG. 1, for example. The vertical axis of FIG. 3A indicates the intensity Ii of the pattern light on the projection surface Pp. The intensity modulation pattern is a periodic modulation pattern. As shown in FIG. 3A, an example of the pattern light is a trigonometric function wave with a modulation amplitude A1, and multiple pattern lights shifted by equal phase intervals are overlapped. As an example, an example is shown in which four trigonometric function wave pattern lights Ii0, Ii1, Ii2, and Ii3 with initial phases of 0 degrees, 90 degrees, 180 degrees, and 270 degrees are overlapped to be used as the pattern light. In this embodiment, the pattern light is an example of the light and dark of a trigonometric function wave, but it may be a rectangular wave pattern light that changes in a rectangular wave shape. The number of pattern lights may be N sheets that satisfy the initial phase of 360 degrees (°) / N, and N may be an integer of 3 or more. Here, the first modulation amplitude A1 is spatially uniform, although this is not necessarily the case.

[0035] Note that the pattern light Ii0 (pattern light in the basic modulation mode) and the pattern light Ii2 (pattern light in the inverse modulation mode) in Fig. 3A are inverted in terms of brightness on the projection surface Pp. Similarly, the pattern light Ii1 and the pattern light Ii3 in Fig. 3A are inverted in terms of brightness on the projection surface Pp.

[0036] The pattern light projected onto the object O is scattered by and passes through the object O. Then, this pattern light reaches the front side of the object O. In this manner, the object O is imaged by the light that has reached the front surface of the object O, and the imaging device 20 acquires an image.

[0037] When the object O is a homogeneous medium, the brightness of the light that reaches the front surface of the object O changes periodically, just like the pattern light projected onto the object O. In other words, when the object O is a homogeneous medium, there is a positive correlation between the intensity of the pattern light projected onto the projection surface Pp and the intensity of the light that reaches the object surface Po. As a result, the intensity Io of the region on the object surface Po facing the region on the projection surface Pp where the intensity Ii is high is greater than the intensity Io of the region on the object surface Po facing the region on the projection surface Pp where the intensity Ii is low.

[0038] Fig. 3B shows an example of light on an object plane Po in response to the projection of the pattern light of Fig. 3A. The horizontal axis of Fig. 3B indicates the position on a line segment on the object plane Po corresponding to a line segment on the projection plane Pp of the object O, for example, on the paper surface (XZ plane) of Fig. 1. The vertical axis of Fig. 3B indicates the intensity Io of light on the object plane Po.

[0039] As shown in FIG. 3B, the modulation amplitude A2 is lower than the amplitude A1 by scattering and transmitting through the object O. That is, the amplitude A2 <A1となる。

[0040] In addition, the pattern light that passes through the unique region S is locally scattered differently due to the effects of cracks and surface scratches, and is transmitted to the object surface Po. The pattern light that appears on the object surface Po after passing through the unique region S has a different shape from the surrounding trigonometric function waves.

[0041] Next, a calculation (specific scattering extraction process) for demodulating the amplitude A2 from the four pattern images (first image group) Io0, Io1, Io2, and Io3 captured by the imaging device 20 will be described.

[0042] Up until now, we have explained the case where there are four pattern lights, but here we will generally explain the calculation method for N patterns (N is an integer of 3 or more). Each of the N patterns has a periodic structure with a phase difference of T / N with respect to the period T. If n is an integer, the phase (radian) of each pattern light is α = 2πn / N. If we focus on a certain point (pixel point) x in a certain space, the pixel value Ion(x) of the pattern image at that point can be thought of as N pixel values ​​sampled in the n direction at equal intervals of 1 / N. In other words, it can be thought of as a function with n as a variable, such as Ion(x) = I(n). By performing a discrete Fourier transform on this variable n and setting the period to 1, the amplitude A2 and initial phase φ in the n direction at this point x can be found.

[0043]

number

[0044] A2·e calculated using equation (1) iφ The magnitude of this is the amplitude A2. In other words, the amplitude A2 is

number

[0045] By performing this calculation on each pixel value of each pattern image (first image group) Io0, Io1, Io2, and Io3, an amplitude image is generated. A specific example for N=4 is shown below. By substituting N=4 into equations (1) and (2), the modulation amplitude A2 is given by

number

[0046] That is, the specific scattering extraction process of the control unit 31 is a process of calculating the modulation amplitude A2 at each pixel point. The pattern images Io0, Io1, Io2, and Io3 as the first image group are images that form the basis of the specific scattering extraction process of the control unit 31.

[0047] Fig. 3C shows an example of an amplitude image generated by capturing an image of light on an object plane Po in response to the projection of the pattern light in Fig. 3B using equations (1) and (2). The horizontal axis of Fig. 3C indicates the position of the captured image corresponding to a line segment on the object plane Po of the object O. The vertical axis of Fig. 3C indicates the modulation amplitude A2 corresponding to the imaging plane Pi.

[0048] As shown in Fig. 3C, a region of object O having uniform scattering characteristics has a modulation amplitude A2, while the amplitude is larger around peculiar region S than the surroundings. In other words, it is possible to distinguish between a region having uniform scattering characteristics and peculiar region S by comparing the magnitude of modulation amplitude A2.

[0049] Here, the modulation amplitude A2 was calculated using formula (1) and formula (2), but it does not have to be the modulation amplitude itself, and for example, an offset value may be added or subtracted from the amplitude, the amplitude may be multiplied by a constant value, a power of the amplitude, or a combination of these may be used. In other words, any calculation that does not destroy the magnitude relationship of the amplitudes will suffice, and hereinafter an image generated by performing such a calculation will be referred to as a specific light scattering image (first specific light scattering image).

[0050] Next, we will describe the modulation direction of the pattern light irradiated from the projector 10 to the object O. In particular, we have found that when inspecting the ends E1a, E2a, E1b, E2b and / or their vicinities (near the ends) of the inspection object, the modulation direction has a significant effect on the extraction accuracy of the peculiar region S.

[0051] In the first embodiment, the modulation direction Dm1 of the pattern light (first modulated pattern light) used by the control unit 31 to generate a scattering image using the projector 10 is approximately parallel to the direction D1 in which the ends E1a, E2a of the object O to be inspected extend.

[0052] FIG. 4 shows an overall image of the object O. The object O shown in FIG. 4 has four ends E1a, E1b, E2a, and E2b. Of these, two ends E1a and E1b are formed parallel or nearly parallel to each other, and the remaining two ends E2a and E2b are formed parallel or nearly parallel to each other. In this embodiment, the ends E1a and E2a are perpendicular to the ends E1b and E2b. The direction in which the ends E1a and E1b extend is defined as D1, and the direction in which the ends E1b and E2b extend is defined as D2.

[0053] Fig. 5A is a scattering image (first unique light scattering image) in which the modulation direction Dm1 of the pattern light is approximately parallel to the direction D1 in which the end E1a of the object O extends, at a position including the end E1a indicated by the symbol V in Fig. 4. The pattern light for obtaining such a scattering image is irradiated onto the object O in sequence, shifted by equal phase intervals, for example λ / 4, in the X-axis direction, as shown in Fig. 3A.

[0054] Fig. 5B is a modulated amplitude image (second specific light scattering image) generated by calculating the amplitude when the modulation direction Dm2 of the pattern light at the position indicated by symbol V in Fig. 4 is a direction D2 that is approximately perpendicular to the direction D1 in which the end E1a of the object O extends. For the pattern light (second modulated pattern light) to obtain such a specific light scattering image, for example, pattern light as shown in Fig. 3A is irradiated onto the object O in sequence, shifted by equal phase intervals, for example λ / 4, in the Y-axis direction instead of the X-axis direction.

[0055] The ends E1a, E2a, E1b, and E2b of the object O are interfaces between the object O and the outside, generally between the object O and the air. It can be said that the scattering characteristics inside the object O are discontinuous at the ends E1a, E2a, E1b, and E2b of the object O. Therefore, singular scattering occurs at the ends E1a, E2a, E1b, and E2b of the object O, similar to the singular region S. The singular scattering at the ends E1a, E2a, E1b, and E2b of the object O increases in intensity in the scattering image, similar to the singular region S caused by a crack or foreign matter. The magnitude of the increase in intensity in the scattering image changes depending on the relationship between the modulation directions Dm1 and Dm2 of the pattern light and the extension directions of the ends E1a, E2a, E1b, and E2b of the object O. As shown in FIG. 5A, if the direction in which the end E1a of the object O extends and the modulation direction Dm1 of the pattern light are almost parallel, there is almost no increase in the modulation amplitude at the end E1a of the object O. However, if the direction D1 in which the end E1a of the object O extends and the modulation direction Dm2 of the pattern light are non-parallel to the end E1a of the object O, for example, as shown in FIG. 5B, the direction D2 is perpendicular to the direction D1 in which the end E1a of the object O extends, an increase in the modulation amplitude due to peculiar scattering occurs near the end E1a of the object O. Such an increase in modulation amplitude due to peculiar scattering near the end E1a of the object O is difficult to distinguish from a peculiar region S to be extracted, such as a crack in the object O. In this embodiment, a peculiar light scattering image generated using a pattern light having a modulation direction Dm1 parallel to the direction D1 in which the end E1a of the object O extends is used to extract the peculiar region S near the end E1a of the object O. By using pattern light having a modulation direction Dm1 parallel to the direction D1 in which the end E1a of the object O extends, it is possible to extract the increase in modulation amplitude on the scattering image caused by the end E1a of the object O without erroneously extracting it, or overlooking the peculiar region S that overlaps with the increased region, thereby improving the accuracy of extraction of the peculiar region S.

[0056] FIG. 6 shows an example of a peculiar light scattering image in which a peculiar region S actually exists at and near the end E1a of the object O. This peculiar light scattering image was generated using a pattern light (see FIG. 5A) having a modulation direction Dm1 that is approximately parallel to the direction D1 in which the end E1a of the object O extends. The desired scattering region of the object O, which indicates the surface of the object O, appears relatively bright, whereas no bright area is generated due to peculiar scattering caused by the end E1a of the object O. Therefore, the optical inspection device 1 can accurately extract the peculiar region S in the region inside the end E1a of the object O by generating a peculiar light scattering image using a pattern light having a modulation direction Dm1 that is parallel to the direction D1 in which the end E1a of the object O extends.

[0057] 7 and 8 are flowcharts showing an optical inspection method performed using the optical inspection device 1 according to the first embodiment. The operations shown in FIGS.

[0058] In step S11, the control unit 31 causes the projector 10 to sequentially project onto the object O pattern light (see FIG. 5A) having a modulation direction Dm1 substantially parallel to the direction D1 in which the end E1a of the object O extends while modulating the pattern light, and causes the imaging device 20 to capture each pattern light passing through the object O. In addition, each image obtained by imaging with the imaging device 20 is held in a predetermined storage area of ​​the storage unit 32 of the control device 30.

[0059] 8, in capturing the pattern light in step S11, the control unit 31 first calls up, for example, a projection pattern having a certain modulation direction Dm1 stored in a predetermined storage area of ​​the storage unit 32 in order to sequentially project the pattern light (first modulated pattern light) onto the object O (step S101). Note that multiple projection patterns Ii0, Ii1, Ii2, and Ii3 having the same modulation direction Dm1 but different phases may be called up at once from the predetermined storage area of ​​the storage unit 32, or the projection patterns Ii0, Ii1, Ii2, and Ii3 may be called up sequentially.

[0060] The projector 10 projects one of the pattern lights (for example, the pattern light Ii0 in FIG. 3A) having a modulation direction Dm1 substantially parallel to the direction D1 in which the end E1a of the object O extends, onto the object O, and the control unit 31 causes the imaging device 20 to capture the pattern light passing through the object O and stores the image (pattern image Io0) in the storage unit 32 (step S102). The image (pattern image Io0) becomes one of the first image group.

[0061] A pattern light (for example, the pattern light Ii1 in FIG. 3A) that is shifted in phase by a predetermined amount from the previously irradiated pattern light (for example, the pattern light Ii0 in FIG. 3A) is projected onto the object O, and the control unit 31 causes the imaging device 20 to capture the pattern light that transmits through the object O and stores the image (pattern image Io1) in the storage unit 32 (step S103). The image (pattern image Io1) becomes one of the first image group.

[0062] Then, the control unit 31 projects pattern light of predetermined N patterns (N is an integer of 3 or more, here 4) onto the object O, and judges whether the pattern light of the predetermined N patterns has been captured by the imaging device 20 and stored in the storage unit 32 (step S104). If the pattern light of the predetermined N patterns (four patterns) has not been projected onto the object O (step S104-No), the control unit 31 projects pattern light (e.g., pattern light Ii2 in FIG. 3A) shifted by a predetermined phase from the pattern light irradiated one time previously (e.g., pattern light Ii1 in FIG. 3A) onto the object O, and the control unit 31 causes the imaging device 20 to capture the pattern light passing through the object O and stores the image (pattern image Io2) in the storage unit 32. The image (pattern image Io2) becomes one of the first image group.

[0063] A pattern light (e.g., pattern light Ii3 in FIG. 3A) that is shifted in phase by a predetermined amount from the previously irradiated pattern light (e.g., pattern light Ii2 in FIG. 3A) is projected onto the object O, and the control unit 31 causes the imaging device 20 to capture the pattern light that transmits through the object O and stores the image (pattern image Io3) in the storage unit 32. The image (pattern image Io3) becomes one of the first image group. That is, the projector 10 projects the first modulated pattern light onto the object O, and the imaging device 20 acquires the first image group.

[0064] When N predetermined patterns of pattern light are projected onto the object O, the image is captured by the imaging device 20, and the image is stored in the memory unit 32 (step S104-Yes), the processing shown in FIG. 8 is terminated, that is, the processing of step S11 by the control unit 31 of the optical inspection device 1 shown in FIG. 7 is terminated, and the control unit 31 subsequently performs the processing of step S12.

[0065] In step S12, the control unit 31 generates a peculiar light scattering image (first peculiar light scattering image) using N (four in this case) captured images (pattern images of the first image group) Io0, Io1, Io2, and Io3 as a peculiar region extraction process (see Figs. 5A and 6). The peculiar light scattering image generated as an inspection image emphasizes the peculiar region S compared to other homogeneous medium regions including the ends E1a and E2a of the object O (see Fig. 6, for example). It should be noted that, as shown in Fig. 5A, there may naturally be cases where the peculiar region S is not visible in the object O.

[0066] In step S13, the control unit 31 outputs a specific light scattering image (first specific light scattering image) as an inspection image for the object O. For example, the control unit 31 displays the inspection image on the display of the output device 37. Alternatively, the control unit 31 transmits the inspection image to an analysis device (image processing device) not shown using the communication interface 35. In this manner, the control unit 31 of the optical inspection device 1 completes a series of processes related to optical inspection (optical inspection method) shown in Figs. 7 and 8.

[0067] The analysis device analyzes the presence or absence of a peculiar region S as a defect such as a crack, for example, by comparing each pixel of the inspection image with a threshold value representing the peculiar region S stored in advance. Such an analysis may be performed by the control unit 31 (see step S14 in FIG. 9). That is, the control unit 31 of the optical inspection device 1 according to this embodiment can determine the presence or absence of a peculiar region S such as a defect, based on the inspection image (specific light scattering image) of the object O.

[0068] As described above, in the first embodiment, a plurality of pattern lights Ii0, Ii1, Ii2, Ii3 having a modulation direction Dm1 substantially parallel to the direction D1 in which the ends E1a, E2a of the object O extend are projected onto the object O, and the control unit 31 generates a peculiar light scattering image from a plurality of images (first image group) Io0, Io1, Io2, Io3 obtained by capturing an image of the object O. In the peculiar light scattering image, no peculiar bright areas resulting from the ends E1a, E2a of the object O are generated, and the peculiar region S can be emphasized. Therefore, the optical inspection device 1 according to this embodiment can acquire information about the peculiar region S of the object O from the peculiar light scattering image.

[0069] The control unit 31 of the optical inspection device 1 according to this embodiment projects, onto the object O, a first modulated pattern light having an intensity modulation pattern in which the modulation direction Dm1 is substantially parallel to the direction D1 in which the ends E1a, E2a of the object O extend, and captures images of the object O onto which the first modulated pattern light is projected to obtain a first image group. Then, the control unit 31 generates, by a peculiar light scattering extraction process, a first peculiar light scattering image which may include an image of a peculiar region S which is located in the end portions E1a, E2a of the object O or in a region inside the end portions E1a, E2a, and which is extracted based on the first image group and which scatters light peculiarly due to the first modulated pattern light. The optical inspection method according to this embodiment includes projecting, onto the object O, a first modulated pattern light having an intensity modulation pattern in which the modulation direction Dm1 is substantially parallel to the direction D1 in which the ends E1a, E2a of the object O extend, and capturing an image of the object O onto which the first modulated pattern light is projected to obtain a first group of images. The optical inspection method also includes generating, by a peculiar scattering extraction process, a first peculiar light scattering image which is located in the end E1a, E2a of the object O or in a region inside the end E1a, E2a, is extracted based on the first group of images, and may include an image of a peculiar region S which scatters light peculiarly due to the first modulated pattern light. The optical inspection program (algorithm) of this embodiment causes a computer to execute the following steps: projecting a first modulated pattern light having an intensity modulation pattern in which the modulation direction Dm1 is approximately parallel to the direction D1 in which the ends E1a, E2a of the object O extend, onto each of the objects; capturing an image of the object O onto which the first modulated pattern light is projected to obtain a first group of images; and generating a first peculiar light scattering image by a peculiar scattering extraction process, the first peculiar light scattering image being located in the end E1a, E2a of the object O or in the area inside the end E1a, E2a, and being extracted based on the first group of images, and which may include an image of a peculiar region S that scatters light specifically due to the first modulated pattern light.

[0070] According to this embodiment, an optical inspection device 1, an optical inspection method, and an optical inspection program can be provided that can suppress erroneous detection of a unique area S, such as a defect, of an object O near the ends E1a, E2a of the object O by using pattern light having an intensity modulation pattern in which the modulation direction Dm1 is approximately parallel to the direction D1 in which the ends E1a, E2a of the object O extend.

[0071] Furthermore, according to the present embodiment, the control unit 31 detects the peculiar region S of the object O by using the first peculiar light scattering image. Therefore, an optical inspection device 1 is provided that can suppress erroneous detection of the peculiar region S, such as a defect, of the object O near the ends E1a, E2a of the object O.

[0072] In this embodiment, an example has been described in which the projection plane Pp of the object O and the object surface Po are parallel or approximately parallel (see Figs. 1 and 4). Although not shown, a case will be considered in which the projection plane Pp of the object O and the object surface Po are non-parallel. For example, the thick part of the object O is less likely to transmit the pattern light than the thin part, and the amplitude of the captured pattern light is reduced. That is, the amplitudes Io0, Io1, Io2, and Io3 (see Fig. 3B) of the normal region, which is the base part of the peculiar light scattering image, are not constant, but if the spatial change rate of the base part is different from the spatial change rate of the bright part due to the peculiar region S such as a defect, the base part and the peculiar region S due to the bright part can be separated by image processing (spatial frequency filter) (see Fig. 3C). Therefore, even if the back surface of the object O is a curved surface or an inclined surface, for example, optical inspection can be performed using the optical inspection device 1 to suppress erroneous detection of the peculiar region S.

[0073] (First Modification) In the first embodiment, an example has been described in which the outer shape of the object O is rectangular.

[0074] Fig. 10 is a schematic diagram showing the modulation direction Dm of the illumination pattern light when the end (outer edge) E of the object O is circular. The object O shown in Fig. 10 is a plate with a thickness of about several millimeters and is optically transparent.

[0075] 10 shows a pattern light in which the modulation direction Dm is the circumferential direction as an example of an intensity pattern in which the direction of the end E of a circular object O and the modulation direction Dm are nearly parallel. In this way, the modulation direction Dm of the pattern light does not need to be spatially uniform, and pattern light that matches the outer shape (end E) of the object O may be used.

[0076] 10, the optical inspection device 1 can perform the optical inspection process according to the flowcharts shown in Fig. 7 to Fig. 9, similarly to the case where the object O is rectangular. That is, the optical inspection device 1 according to this embodiment can provide an optical inspection device 1, an optical inspection method, and an optical inspection program that can suppress erroneous detection of a unique region S, such as a defect, of the object O near the end E of the object O by using pattern light having an intensity modulation pattern in which the modulation direction Dm of the pattern light from the projector 10 is substantially parallel to the direction in which the end E of the object O extends, even when the end E of the object O is not a straight line but an appropriate curve.

[0077] (Second Modification) In the first embodiment, an example has been described in which an image of the object O is captured with pattern light that has been transmitted from the back surface to the front surface of the object O. In contrast, as shown in FIG. 11, the object O may be captured with pattern light that has been reflected by the back surface of the object O. In this case, the projector 10 and the image capture device 20 are both installed on the back surface of the object O. In addition, in this case, the projection surface Pp and the object surface Po of the object O are both the back surface of the object O.

[0078] 11, the optical inspection device 1 includes a projector 10, an imaging device 20, a control device 30, and a beam splitter 40. The projector 10 and the imaging device 20 are arranged so that the projection optical axis zp of the projector 10 and the imaging optical axis zi of the imaging device 20 intersect perpendicularly at the beam splitter 40. However, this is not limited thereto, and an oblique incidence arrangement may be used in which the projector 10 and the imaging device 20 are arranged so that the projection optical axis zp and the imaging optical axis zi intersect at an angle.

[0079] In the optical inspection device 1 according to this modification, the object O is not imaged with light transmitted from the back surface to the front surface of the object O, but is imaged with light reflected by the back surface of the object O. That is, in the optical inspection device 1 according to this modification, both the projection plane Pp and the object surface Po of the object O are the back surface of the object O.

[0080] The beam splitter 40 is a non-polarizing splitter or a polarizing splitter. Alternatively, the beam splitter 40 may be a dichroic mirror. When the beam splitter 40 is a polarizing splitter, it transmits the regular reflection component from the object O among the pattern light projected on the object O, and reflects only the scattered component that is scattered and reflected toward the imaging device 20. This is because the polarization generally changes due to scattering. As described above, the unique region S exhibits unique scattering characteristics different from the surrounding uniform medium. On the other hand, the reflected light from the uniform medium generally contains a large amount of regular reflection components. In other words, when the beam splitter 40 is a polarizing splitter, it is easy to extract only the scattered light from the unique region S. When the beam splitter 40 is a non-polarizing splitter, it is possible to make the projection optical axis zp and the imaging optical axis zi coincident.

[0081] (Third Modification) A third modified example of the first embodiment will be described with reference to FIG.

[0082] In the first embodiment, the pattern lights Ii0, Ii1, Ii2, and Ii3 are white light. In contrast, in this modified example, the pattern lights Ii0, Ii1, Ii2, and Ii3 have different wavelength spectra. For example, the pattern light Ii0 is blue light, and the pattern light Ii1 is red light. The pattern light Ii2 is green light. In this modified example, the three pattern lights Ii0, Ii1, and Ii2 are used, and the pattern light Ii3 is not used.

[0083] For example, blue light has a peak wavelength at 450 nm, red light has a peak wavelength at 650 nm, and green light has a peak wavelength at 550 nm. However, the combination of the pattern lights Ii0, Ii1, and Ii2 is not limited to this. In other words, the combination of the pattern lights Ii0, Ii1, and Ii2 may be any combination of different wavelength spectra.

[0084] The image sensor 22 in this modification is configured to be able to independently receive each of the pattern light beams Ii0, Ii1, and Ii2 having different wavelength spectra. For example, the image sensor 22 includes imaging pixels having spectral sensitivity to red light, blue light, and green light. As a result, an image acquired by the image sensor 22 has a color channel corresponding to red light, a color channel corresponding to blue, and a color channel corresponding to green. An image including light projected with the pattern light Ii0 can be acquired from the color channel corresponding to red light. Similarly, an image including light projected with the pattern light Ii1 can be acquired from the color channel corresponding to blue light. An image including light projected with the pattern light Ii2 can be acquired from the color channel corresponding to green light.

[0085] 12 is a flowchart showing an optical inspection method according to a modified example of the first embodiment. The operation of FIG.

[0086] In step S102a, the control unit 31 causes the projector 10 to project a red light pattern light Ii0 onto the object O. In addition, in step S102b, the control unit 31 causes the projector 10 to project a blue light pattern light Ii1 onto the object O. In addition, in step S102c, the control unit 31 causes the projector 10 to project a green light pattern light Ii2 onto the object O. In this modification, the projection of the pattern light Ii0, Ii1, and Ii2 may be performed simultaneously or at the same time, and the pattern light Ii0, Ii1, and Ii2 may be photographed simultaneously or at the same time (the photographing of the first image group).

[0087] A red light image Io0 corresponding to the red light pattern light Ii0, a blue light image Io1 corresponding to the blue light pattern light Ii1, and a green light image Io2 corresponding to the green light pattern light Ii2 obtained by imaging with the imaging device 20 are stored in a predetermined storage area of ​​the storage unit 32 of the control device 30. Even if the images Io0, Io1, and Io2 are captured in a single shooting, they are processed as separate images Io0, Io1, and Io2 for each color by spectral analysis.

[0088] In step S12, the control unit 31 calculates the difference in pixel value (amplitude) for each pixel of the images Io0, Io1, and Io2 as a peculiar region extraction process, and generates a peculiar light scattering image.

[0089] In step S13, the control unit 31 outputs an inspection image of the object O. Thereafter, the processing of FIG. 12 ends. For example, the control unit 31 displays the inspection image on the display of the output device 37. Alternatively, the control unit 31 transmits the inspection image to an analysis device (not shown) using the communication interface 35. The analysis device analyzes the presence or absence of defects (peculiar regions S) such as cracks by, for example, comparing the pixel value of each pixel of the inspection image with a threshold value representing the peculiar region S stored in advance. Such an analysis may be performed by the control unit 31.

[0090] As described above, in this modification, the plurality of pattern lights Ii0, Ii1, Ii2 have different wavelength spectra, the plurality of pattern lights Ii0, Ii1, Ii2 are irradiated onto the object O at the same time, and images Io0, Io1, Io2 (first image group) corresponding to the plurality of pattern lights Ii0, Ii1, Ii2 are captured at the same time. That is, according to the optical inspection device 1 of this modification, it is not necessary to sequentially irradiate the plurality of pattern lights Ii0, Ii1, Ii2 and capture each of them. Therefore, by using the pattern lights Ii0, Ii1, Ii2 according to this modification, the inspection time can be shortened.

[0091] Second Embodiment Next, the optical inspection device 1 according to the second embodiment will be described with reference to Fig. 13A to Fig. 15. In the following, the description common to the optical inspection device 1 according to the first embodiment will be omitted as appropriate. Here, the basic configuration of the optical inspection device 1 according to the second embodiment can be the same as that shown in Fig. 1 and Fig. 2.

[0092] In the first embodiment, the modulation direction Dm1 of the pattern light (first modulated pattern light) is set to be approximately parallel to the direction D1 in which the ends E1a, E2a of the object O extend. However, depending on the shape of the peculiar region S, there may be cases where the emphasis in the peculiar light scattering image (first peculiar light scattering image) is not very strong. For example, when the peculiar region S has a linear shape approximately parallel to the direction D1 in which the ends E1a, E2a of the object O extend, and the modulation direction Dm of the pattern light is approximately parallel to the direction D1 in which the ends E1a, E2a of the object O extend, it has been found that the emphasis in the peculiar light scattering image decreases and the extraction accuracy of the peculiar region S may deteriorate. On the other hand, when using a pattern light (second modulated pattern light) in which the modulation direction Dm2 is non-parallel to the direction D1 in which the linear peculiar region S extends, the peculiar region S is emphasized in the peculiar light scattering image, so that the optical inspection device 1 can increase the extraction accuracy of the peculiar region S. That is, even with the same single continuous unique region S, depending on the modulation directions Dm1, Dm2 of the pattern light, there may be cases where it is emphasized in the unique light scattering image and cases where it is difficult to emphasize in the unique light scattering image.

[0093] For example, in the case of a crack occurring in the object O, the crack often starts from the end E1a of the object O, progresses from the end E1a of the object O toward the inside, and takes on a linear shape. Since the crack is non-parallel to the direction D1 in which the end E1a of the object O extends near the end E1a of the object O, the crack can be extracted as a peculiar region S by the processing of the optical inspection device 1 described in the first embodiment. However, the direction of the crack that has progressed further toward the inside of the object O may be almost parallel to the direction D1 in which the end E1a of the object O extends. In that case, it can be emphasized by a peculiar light scattering image using a pattern light that is non-parallel to the direction D1 in which the end E1a of the object O extends.

[0094] In the optical inspection device 1 of the second embodiment, in addition to the optical inspection processing in the optical inspection device 1 of the first embodiment, an example is described in which optical inspection processing is performed using pattern light that is non-parallel to the direction D1 in which the end E1a of the object O extends.

[0095] 13A and 13B are schematic diagrams showing a peculiar light scattering image generated using pattern light (second modulated pattern light) that is non-parallel to the direction D1 in which the end E1a of the object O extends, and the inspection target region R in the peculiar light scattering image. When non-parallel pattern light is used, the end E1a of the object O appears as a bright part in the peculiar light scattering image, similar to the peculiar region S, due to peculiar scattering caused by the end E1a of the object O, which may cause erroneous extraction of the peculiar region S.

[0096] FIG. 13A shows that a position that is a certain distance d or more away from the end E1a of the object O is set as the inspection target region R. This method can be used when the position of the object O does not always change in the image to be acquired, or when the position of the end E1a of the object O is easy to detect by image processing. The certain distance d is preferably set to a value corresponding to the maximum value of the variation in the position of the object O in the image acquired in response to the irradiation of the pattern light, or the detection error of the end E1a of the object O in the image processing, in addition to the width of the bright part caused by the end E1a of the object O. By setting the region R that is a certain distance d or more away from the end E1a of the object O as the inspection target region in this way, the optical inspection device 1 can extract the desired peculiar region S in the region R1 without detecting the bright part that appears at the end E1a of the object O, or, even if it detects it, ignore it because it is outside the region R.

[0097] As shown in FIG. 14B, the boundary of the inspection region R within the range on the lower side of the paper surface of FIG. 14B is set at a position away from the end E2a of the object O opposite the end E1a, by a certain distance d or more toward the end E1a.

[0098] Also, as shown in FIG. 13B, a part of the bright part appearing at the end E1a of the object O in the peculiar light scattering image can be detected, and the region excluding the part of the bright part toward the end E2a on the opposite side of the end E1a can be set as the upper end of the paper in FIG. 14B of the inspection target region R. Similarly, a part of the bright part appearing at the end E2a of the object O in the peculiar light scattering image can be detected, and the region excluding the part of the bright part toward the end E1a on the opposite side of the end E2a can be set as the lower end of the paper in FIG. 14A of the inspection target region R. The bright parts appearing at the ends E1a and E2a of the object O can be detected, for example, by determining a certain threshold value and setting the region to be a continuously extending region that is equal to or greater than the threshold value. Then, image processing can be performed to set the region excluding the detected bright part as the inspection target region R, and a range in which the desired peculiar region S can be extracted can be set. In the case of the example shown in FIG. 13B, the inspection target region R can be made larger than the example shown in FIG. 13A.

[0099] By setting the modulation direction Dm2 of the non-parallel pattern light to a direction that is approximately parallel to the other ends E1b, E2b of the object O, the entire object O can be covered as the inspection target area R, and the number of pattern lights projected can be reduced compared to projecting pattern light with a random modulation direction.

[0100] 14A and 14B are schematic diagrams showing an example of a set range of an inspection target region R for inspecting an object O having a parallelogram outer shape (end portion) using pattern light. FIG. 14A shows an example of using pattern light (first modulated pattern light) having a first modulation direction Dm1 described in the first embodiment, which is substantially parallel to the direction D2 in which the upper end E1a and the lower end E2a extend. A specific light scattering image generated by projecting the pattern light having the first modulation direction Dm1 is defined as S1(m,n). In the specific light scattering image S1(m,n), no bright areas are generated at the upper end E1a and the lower end E2a in FIG. 14A. However, since the modulation direction Dm1 is non-parallel to the direction D1 in which the left end E1b and the right end E2b in FIG. 14A extend, the positions corresponding to the ends E1b and E2b in the specific light scattering image S1(m,n) become bright areas. Here, an inner region that is a certain distance d or more away from the left end E1b and the right end E2b is defined as a first inspection region R1.

[0101] FIG. 14B shows an example of using a pattern light (second modulated pattern light) having a second modulation direction Dm2 that is substantially parallel to the direction D2 in which the left end E1b and the right end E2b extend. A specific light scattering image generated by projecting the pattern light having the second modulation direction Dm2 is designated as S2(m,n). In the specific light scattering image S2(m,n), no bright areas are generated at the left end E1b and the right end E2b in FIG. 14B. However, since the modulation direction Dm2 is non-parallel to the upper end E1a and the lower end E2a in FIG. 14B, the positions corresponding to the ends E1a and E2a in the specific light scattering image S2(m,n) become bright areas. Here, the internal regions that are a certain distance d or more away from the upper end E1a and the lower end E2a are designated as the second inspection target region R2.

[0102] The combined area of ​​the first inspection target area R1 and the second inspection target area R2 corresponds to the entire front and back surfaces of the object O.

[0103] In this way, when pattern light of two different modulation directions Dm1, Dm2 is used, the result of combining the unique region extracted using the unique light scattering image S1(m,n) and the unique region extracted using the unique light scattering image S2(m,n) can be extracted as the unique region S of the object O according to this embodiment. In this case, in the region where the inspection target region R1 by the first modulation direction Dm1 and the inspection target region R2 by the second modulation direction Dm2 overlap, extraction with little dependency on the shape of the unique region S is possible. Therefore, the optical inspection device 1 can extract the unique region S more reliably. In other words, although a part of the extracted unique region may differ from a part of the extracted unique region, when pattern light of two different modulation directions Dm1, Dm2 is used, these can be extracted respectively.

[0104] FIG. 15 is a flowchart showing an optical inspection method performed using the optical inspection device 1 according to the second embodiment. The operation of FIG. 15 can be controlled by the control unit 31 of the control device 30. The process of FIG. 15 is a modification of the pattern light imaging process of step S11 of FIG. 8 described in the first embodiment. The basic flow of the optical inspection device 1 according to the second embodiment is the same as the flow of the optical inspection device 1 according to the first embodiment shown in FIG. 7.

[0105] Steps S101 to S104 in step S11 are the same as the flow of the optical inspection device 1 described in the first embodiment. Each image in the first image group is obtained as an image of a region including the four ends of the object O, and as shown in Fig. 14A, for example, a region that is a distance d or more away from the left end E1b, to the right of the position of distance d, and a distance d or more away from the right end E2b, to the left of the position of distance d is set as the detection range R1.

[0106] The control unit 31 causes the projector 10 to project one of the pattern lights (light along the direction D2 corresponding to the pattern light Ii0 shown in FIG. 3A) having a modulation direction Dm2 non-parallel to the direction D1 in which the upper end E1a and the lower end E2a of the object O extend, and parallel to the direction D2 in which the left end E1b and the right end E2b extend, onto the object O, causes the imaging device 20 to capture the pattern light passing through the object O, and causes the storage unit 32 to store the image (pattern image Io0) (step S105). The image (pattern image Io0) becomes one of the second image group.

[0107] A pattern light (light along the direction D2 corresponding to the pattern light Ii1 shown in FIG. 3A) that is shifted by a predetermined phase from the previously irradiated pattern light (light along the direction D2 corresponding to the pattern light Ii0 shown in FIG. 3A) is projected onto the object O, and the control unit 31 causes the imaging device 20 to capture the pattern light that transmits through the object O and stores the image (pattern image Io1) in the storage unit 32 (step S106). The image (pattern image Io1) becomes one of the second image group.

[0108] Then, the control unit 31 projects pattern light of a predetermined N patterns (N is an integer of 3 or more, here 4) onto the object O, and judges whether the pattern light of the predetermined N patterns has been captured by the imaging device 20 and stored in the storage unit 32 (step S107). If the pattern light of the predetermined N patterns (for example, 4 patterns) has not been projected onto the object O (step S107-No), the control unit 31 projects pattern light (light along the direction D2 corresponding to the pattern light Ii2 shown in FIG. 3A) shifted by a predetermined phase from the pattern light irradiated one time previously (light along the direction D2 corresponding to the pattern light Ii1 shown in FIG. 3A) onto the object O, and the control unit 31 causes the imaging device 20 to capture the pattern light passing through the object O and stores the image (pattern image Io2) in the storage unit 32. The image (pattern image Io2) becomes one of the second image group.

[0109] A pattern light (light along the direction D2 corresponding to the pattern light Ii3 shown in FIG. 3A) that is shifted by a predetermined phase from the previously irradiated pattern light (light along the direction D2 corresponding to the pattern light Ii2 shown in FIG. 3A) is projected onto the object O, and the control unit 31 causes the imaging device 20 to capture the pattern light that transmits through the object O and stores the image (pattern image Io3) in the storage unit 32. The image (pattern image Io3) becomes one of the second image group.

[0110] When N predetermined patterns of pattern light are projected onto the object O, the image is captured by the imaging device 20, and the image is stored in the memory unit 32 (step S107-Yes), the processing shown in FIG. 15 is terminated, that is, the processing of step S11 by the control unit 31 of the optical inspection device 1 shown in FIG. 7 is terminated, and the control unit 31 subsequently performs the processing of step S12.

[0111] In this embodiment, an example in which different pattern lights are irradiated multiple times, imaged, and stored can be described. As described with reference to FIG. 12, a set of, for example, three first pattern lights shifted by λ / 4 each can be used, and the image sensor 22 can be used to obtain RGB by dispersing the first pattern lights. In this case, a set of, for example, three first pattern lights shifted by λ / 4 each can be irradiated at the same time, imaged, and stored, and a set of, for example, three second pattern lights shifted by λ / 4 each can be irradiated at the same time, imaged, and stored, so that the control unit 31 of the optical inspection device 1 can perform the process of step S11.

[0112] Each image in the second image group is obtained as an image of an area including the four ends E1a, E2a, E1b, and E2b of the object O. As shown in FIG. 14B, for example, the area below the position at distance d from the upper end and above the position at distance d from the lower end is set as the detection range R2, i.e., the area to be subjected to the peculiar area extraction process.

[0113] In step S12, as a peculiar region extraction process, the control unit 31 generates a peculiar light scattering image (first peculiar light scattering image) within the detection range R1 shown in FIG. 14A using N (here, four) captured images (pattern images) Io0, Io1, Io2, Io3 of the first image group, and generates a peculiar light scattering image (second peculiar light scattering image) within the detection range R2 shown in FIG. 14B using N (here, four) captured images (pattern images) Io0, Io1, Io2, Io3 of the second image group.

[0114] In step S13, the control unit 31 outputs two specific light scattering images (a first specific light scattering image and a second specific light scattering image) as inspection images for the object O. For example, the control unit 31 displays the inspection images on the display of the output device 37. Alternatively, the control unit 31 transmits the inspection images to an analysis device (image processing device) not shown using the communication interface 35. In this manner, the control unit 31 of the optical inspection device 1 completes a series of processes related to optical inspection (optical inspection method) shown in Figs. 7 and 15.

[0115] As described in the first embodiment, the analysis device can analyze the presence or absence of defects such as cracks by, for example, comparing each pixel of an inspection image (first specific light scattering image) in which a detection range R1 is specified and an inspection image (second specific light scattering image) in which a detection range R2 is specified with a threshold value representing a specific region S that is stored in advance. Alternatively, the analysis device can analyze the presence or absence of defects such as cracks by comparing each pixel in an image obtained by superimposing the detection range R1 of the first specific light scattering image and the detection range R2 of the second specific light scattering image with a threshold value representing the specific region S that has been stored in advance.

[0116] In the present embodiment, the first image group is obtained by a first pattern light in which the modulation direction Dm1 is substantially parallel to the direction D1 in which the ends E1a and E2a of the object O extend, and then the second image group is obtained by a second pattern light in which the modulation direction Dm2 is non-parallel, such as intersecting the direction D1 in which the ends E1a and E2a of the object O extend, and the modulation direction Dm2 is substantially parallel to the direction D2 in which the ends E1b and E2b of the object O extend. The control unit 31 of the optical inspection device 1 may obtain the second image group first, for example, and then obtain the first image group. In addition, the control unit 31 of the optical inspection device 1 may obtain, for example, a partial image of the first image group first, then a partial image of the second image group, and then obtain the remaining image of the first image group. For this reason, the order for obtaining both the first image group and the second image group may be random or may be set appropriately.

[0117] As described above, in the optical inspection device 1 according to the second embodiment, a first peculiar light scattering image is generated from a plurality of images obtained by projecting a plurality of pattern lights (first modulated pattern lights) onto the object O, the object O being imaged. In the first peculiar light scattering image, no peculiar bright areas due to the ends of the object O are generated, and only the peculiar region S can be emphasized. Furthermore, in the optical inspection device 1 according to the second embodiment, a plurality of pattern lights (second modulated pattern lights) having a modulation direction Dm2 that is non-parallel to the direction D1 in which the ends E1a and E2a of the object O extend and parallel to the direction D2 in which the ends E1b and E2b of the object O extend are projected onto the object O, and a second peculiar light scattering image different from the first peculiar light scattering image is generated from a plurality of images obtained by imaging the object O. In this second peculiar light scattering image, by setting the region R2 inside the peculiar bright areas caused by the ends E1a, E2a of the object O as the region to be inspected, it is possible to improve the accuracy of extraction of the peculiar region S in the region to be inspected.

[0118] The control unit 31 of the optical inspection device 1 according to this embodiment projects onto the object O a second modulated pattern light having an intensity modulation pattern with a modulation direction non-parallel to the direction of the ends E1a, E2a of the object O and a modulation direction different from that of the first modulated pattern light, and captures images of the object O onto which the second modulated pattern light is projected to obtain a second image group. Then, the control unit 31 generates, by a peculiar scattering extraction process, a second peculiar light scattering image that is located at a position at least a certain distance d away from the ends E1a, E2a of the object O, is extracted based on the second image group, and may include an image of a peculiar region S that scatters light peculiarly due to the second modulated pattern light.

[0119] Furthermore, according to the present embodiment, the control unit 31 detects the peculiar region S of the object O by using the second peculiar light scattering image. Therefore, an optical inspection device 1 is provided that can suppress erroneous detection of the peculiar region S, such as a defect, of the object O near the ends E1a, E2a of the object O.

[0120] Therefore, according to the present embodiment, it is possible to provide the optical inspection device 1, the optical inspection method, and the optical inspection program that are capable of suppressing erroneous detection of the unique region S such as a defect.

[0121] In this embodiment, two pattern lights having different modulation directions, that is, two modulation directions Dm1 and Dm2, are used, but this is not limited thereto, and three or more pattern lights may be used and the modulation directions may be three or more. For example, when optically inspecting an object O having a trapezoidal outer shape, a first modulated pattern light having an intensity modulation pattern in which the modulation direction Dm1 is approximately parallel to the direction in which a pair of parallel ends extend is projected onto the object, a first modulated pattern light having an intensity modulation pattern in which the modulation direction Dm2 is approximately parallel to the direction in which one of the remaining two ends extends is projected onto the object, and a first modulated pattern light having an intensity modulation pattern in which the modulation direction Dm3 (not shown) is approximately parallel to the direction in which the remaining end extends is projected onto the object, and each image is obtained, thereby providing an optical inspection device 1, an optical inspection method, and an optical inspection program that can suppress erroneous detection of a unique area such as a defect.

[0122] (Modification) In the second embodiment, an example has been described in which the outer shape of the object O is rectangular. Fig. 16 shows an object O having a circular outer edge, the same as the object O shown in Fig. 10. Fig. 16 also shows pattern light in which the modulation direction Dm shown in Fig. 10 is not the circumferential direction of the end E of the object O, but is the radial direction of the object O.

[0123] The control unit 31 of the optical inspection device 1 acquires a first group of images using pattern light (first modulated pattern light) whose modulation direction Dm is approximately parallel to the direction D in which the end E of the object O extends, as in the example shown in FIG. 10. Moreover, the control unit 31 of the optical inspection device 1 acquires a second group of images using pattern light (second modulated pattern light) whose modulation direction Dm is non-parallel to the direction D in which the end E of the object O extends, as in the example shown in FIG. 16. Therefore, the control unit 31 outputs two specific light scattering images (first specific light scattering image, second specific light scattering image) as inspection images for the object O. At this time, the first specific light scattering image in the example shown in FIG. 10 has the entire surface including the end E of the object O as the inspection target region R. Then, the first peculiar light scattering image by pattern light having a modulation direction Dm parallel to the direction D in which the end E of the object O extends can detect the peculiar region S excluding the end E and the peculiar region S parallel to the direction D in which the end E extends. Meanwhile, the second peculiar light scattering image of the example shown in FIG. 16 sets the inspection target region R to a region inside a position a predetermined distance d away from the end E of the object O. Then, the second peculiar light scattering image by pattern light having a modulation direction Dm parallel to the radial direction and perpendicular to the direction D in which the end E of the object O extends can detect the peculiar region S excluding the peculiar region S extending in a direction perpendicular to the direction D in which the end E extends.

[0124] Therefore, according to this modification, it is possible to provide the optical inspection device 1, the optical inspection method, and the optical inspection program that are capable of suppressing erroneous detection of the unique region S such as a defect.

[0125] According to at least one of the optical inspection apparatus 1, the optical inspection method, and the optical inspection program of the embodiment described above, it is possible to suppress erroneous detection of a unique area such as a defect.

[0126] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0127] 1...optical inspection device, 10...projector, 20...imaging device, 30...control device, 31...control unit, 32...memory unit, 33...power supply unit, 34...timing device, 35...communication interface, 36...input unit, 37...output device, 38...external interface, Ii0, Ii1, Ii2, Ii3...pattern light, Io0, Io1, Io2...pattern image (captured image), O..., object, S...singular area.

Claims

1. a first modulation pattern light having an intensity modulation pattern in which the modulation direction is substantially parallel to a direction in which an end portion of the object extends, is projected onto the object; capturing an image of each of the objects onto which the first modulated pattern light is projected to obtain a first group of images; generating a first peculiar light scattering image by a peculiar scattering extraction process, the first peculiar light scattering image being located at the end of the object or in an area inside the end, extracted based on the first image group, and which may include an image of a peculiar area that scatters light peculiarly due to the first modulated pattern light; An optical inspection device having a control unit.

2. The optical inspection device according to claim 1 , wherein the control unit detects the peculiar region of the object by using the first peculiar light scattering image.

3. The control unit is projecting a second modulation pattern light having a modulation direction non-parallel to a direction of the end of the object and an intensity modulation pattern having a modulation direction different from that of the first modulation pattern light onto the object; capturing images of the objects onto which the second modulated pattern light is projected to obtain a second group of images; generating a second peculiar light scattering image by the peculiar scattering extraction process, the second peculiar light scattering image being located at a position at least a certain distance away from the end of the object, being extracted based on the second image group, and which may include an image of a peculiar region that scatters light peculiarly due to the second modulated pattern light; 3. The optical inspection device according to claim 1 or 2.

4. The optical inspection device according to claim 3 , wherein the control unit detects the peculiar region of the object by using the second peculiar light scattering image.

5. 3. The optical inspection device according to claim 1, wherein the specific scattering extraction process by the control unit is a process for calculating a modulation amplitude at each pixel point.

6. 3. The optical inspection device according to claim 1, wherein the intensity modulation pattern is a periodic modulation pattern.

7. a projector that is controlled by the control unit and projects the first modulated pattern light onto the object; an imaging device controlled by the control unit to acquire the first image group; The optical inspection device according to claim 1 or 2, further comprising:

8. projecting a first modulation pattern light having an intensity modulation pattern in which a modulation direction is substantially parallel to a direction in which an end portion of the object extends, onto the object; acquiring a first group of images by capturing images of the objects onto which the first modulated pattern light is projected; generating a first peculiar light scattering image by a peculiar scattering extraction process, the first peculiar light scattering image being located at the end of the object or in an area inside the end, extracted based on the first image group, and which may include an image of a peculiar area that scatters light peculiarly due to the first modulated pattern light; An optical inspection method comprising:

9. detecting the anomalous region of the object using the first anomalous light scattering image; The optical inspection method of claim 8 , comprising:

10. projecting, onto the object, a second modulated pattern light having an intensity modulation pattern with a modulation direction non-parallel to a direction of the end of the object and different from that of the first modulated pattern light; acquiring a second group of images by capturing images of the objects onto which the second modulated pattern light is projected; generating, by the peculiar scattering extraction process, a second peculiar light scattering image which is located at a position at least a certain distance away from the end of the object, is extracted based on the second image group, and may include an image of a peculiar region which scatters light peculiarly due to the second modulated pattern light; The optical inspection method according to claim 8 or claim 9, comprising:

11. detecting the anomalous region of the object using the second anomalous light scattering image; The optical inspection method of claim 10 , comprising:

12. projecting a first modulation pattern light having an intensity modulation pattern in which a modulation direction is substantially parallel to a direction in which an end portion of the object extends, onto the object; acquiring a first group of images by capturing images of the objects onto which the first modulated pattern light is projected; generating a first peculiar light scattering image by a peculiar scattering extraction process, the first peculiar light scattering image being located at the end of the object or in an area inside the end, extracted based on the first image group, and which may include an image of a peculiar area that scatters light peculiarly due to the first modulated pattern light; An optical inspection program that causes a computer to execute the above steps.

13. The optical inspection program of claim 12 , further comprising: detecting the anomalous region of the object using the first anomalous light scattering image.

14. projecting, onto the object, a second modulated pattern light having an intensity modulation pattern with a modulation direction non-parallel to a direction of the end of the object and different from that of the first modulated pattern light; acquiring a second group of images by capturing images of the objects onto which the second modulated pattern light is projected; generating, by the peculiar scattering extraction process, a second peculiar light scattering image which is located at a position at least a certain distance away from the end of the object, is extracted based on the second image group, and may include an image of a peculiar region which scatters light peculiarly due to the second modulated pattern light; The optical inspection program according to claim 12 or 13, which causes the computer to execute the steps of:

15. detecting the anomalous region of the object using the second anomalous light scattering image; The optical inspection program according to claim 14, which causes the computer to execute the steps:

Images