Defect inspection equipment and defect inspection methods

Abstract

This invention provides a defect inspection apparatus and a defect inspection method that can easily determine the presence or absence of cracks of various depths without changing the angle of the object being inspected relative to the measuring unit. The defect inspection apparatus (100) includes: an excitation unit (1); an irradiation unit (laser illumination 2) for irradiating with laser light; and a measuring unit (3) for changing the phase of the laser light reflected by the object being inspected (8), causing the laser light before and after the phase change to interfere with each other, and measuring the interference light. Furthermore, the measuring unit (3) acquires an interference image (71) representing the vibration state of the object being inspected (8) as observed from the direction along a first optical path (21), and acquires an interference image (72) representing the vibration state of the object being inspected (8) as observed from the direction along a second optical path (22) reflected from the object being inspected in a direction different from the first optical path (21).

Description

Technical Field

[0001] This invention relates to a defect inspection device and a defect inspection method. Background Technology

[0002] Previously, defect inspection devices and methods for optically inspecting defects such as cracks or peeling that occur on the surface and inside of an object being inspected were known. Such defect inspection methods have been disclosed, for example, in Japanese Patent Application Publication No. 2017-219318.

[0003] Japanese Patent Application Publication No. 2017-219318 discloses a defect inspection device, comprising: an excitation unit for exciting elastic waves onto an object to be inspected; an illumination unit for stroboscopic illumination of a measurement area on the surface of the object to be inspected; and a displacement measurement unit (speckle shear interferometer). The displacement measurement unit is configured to simultaneously measure the displacement of each point in the measurement area in a direction orthogonal to the surface of the object to be inspected, under different phases of the elastic waves, by controlling the phase of the elastic waves and the timing of the stroboscopic illumination. In the defect inspection device described in Japanese Patent Application Publication No. 2017-219318, an image is generated based on the vibration state (amplitude and phase) of each point in the measurement area, representing the difference in displacement in a direction orthogonal to the vibrating surface of the object to be inspected, using the difference in image brightness. For example, when a defect occurs in the object to be inspected, the vibration state becomes discontinuous at the defective portion (with the defective end as the boundary), and the brightness of the image changes drastically. By visually inspecting or image processing the image, the discontinuity in the vibration state is detected as a defect.

[0004] [Existing Technical Documents]

[0005] [Patent Literature]

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-219318 Summary of the Invention

[0007] [The problem the invention aims to solve]

[0008] Although not explicitly described in Japanese Patent Application Publication No. 2017-219318, the propagation of vibration exists in both a direction orthogonal to the surface of the object being inspected (vertical direction) and a direction along the surface (in-plane direction). Furthermore, in the case of a relatively deep crack in the object being inspected, a significant discontinuity (displacement) in the vibration state occurs in both the vertical direction orthogonal to the surface of the object being inspected and the direction along the surface (in-plane direction). On the other hand, in the case of a relatively shallow crack in the object being inspected, the discontinuity (displacement) in the vibration state in the vertical direction orthogonal to the surface of the object being inspected is less pronounced. In conventional defect inspection devices as described in Japanese Patent Application Publication No. 2017-219318, the presence or absence of defects is determined based on the obtained discontinuity (displacement) in the vibration state of the object being inspected in the vertical direction orthogonal to the surface of the object being inspected; therefore, the presence or absence of relatively deep cracks can be determined. On the other hand, in existing defect inspection devices as described in Japanese Patent Application Publication No. 2017-219318, it is difficult to easily determine whether there are small, shallow cracks caused by discontinuities (displacements) in the vibration state in a direction orthogonal to the surface of the object being inspected. Furthermore, although not explicitly described in Japanese Patent Application Publication No. 2017-219318, the direction of the discontinuity (displacement) in the vibration state obtained (observed) by existing defect inspection devices as described in Japanese Patent Application Publication No. 2017-219318 is the direction that bisects the angle formed by the illumination unit and the displacement measuring unit relative to the object being inspected.

[0009] Therefore, in existing defect inspection devices as described in Japanese Patent Application Publication No. 2017-219318, determining the presence or absence of relatively shallow cracks requires changing the angle of the object under inspection relative to the displacement measuring unit, thereby altering the direction of the discontinuity (displacement) in acquiring the vibration state (the direction of acquiring the interference image). Thus, it is necessary to change the angle of the object under inspection relative to the measuring unit according to the depth of the crack. Therefore, it is desirable to easily determine the presence or absence of cracks of various depths (relatively deep cracks or relatively shallow cracks, etc.) without changing the angle of the object under inspection relative to the measuring unit.

[0010] The present invention was made to solve the aforementioned problems. One object of the present invention is to provide a defect inspection device and defect inspection method that can easily determine the presence or absence of cracks of various depths without changing the angle of the object to be inspected relative to the measuring part.

[0011] [Technical means to solve the problem]

[0012] The defect inspection apparatus of the first aspect of the present invention includes: an excitation unit that imparts elastic wave vibration to and excites an object to be inspected; an irradiation unit that irradiates the object to be inspected in a state of elastic wave vibration excited by the excitation unit with a laser; and a measurement unit that causes a phase change in the laser reflected by the object to be inspected, causes the lasers before and after the phase change to interfere with each other, and measures the interference light. The measurement unit is configured to acquire an interference image representing the vibration state of the object to be inspected as observed from the direction along the first optical path, based on the interference light of the laser irradiated from the irradiation unit and reflected from the object to the measurement unit in a first optical path, and to acquire an interference image representing the vibration state of the object to be inspected as observed from the direction along the second optical path, based on the interference light of the laser irradiated from the irradiation unit and reflected from the object to a second optical path in a direction different from the first optical path.

[0013] The defect inspection method of the second aspect of the present invention involves subjecting an object to inspection to elastic wave vibration and exciting it, irradiating the object to inspection with a laser while it is in the excited state of elastic wave vibration, and obtaining an interference image representing the vibration state of the object to inspection as observed from the direction along the first optical path based on the interference light of the laser reflected by the measuring unit that causes a phase change in the laser reflected by the object to inspection, causes the laser before and after the phase change to interfere with each other, and measures the interference light. Furthermore, an interference image representing the vibration state of the object to inspection as observed from the direction along the second optical path is obtained based on the interference light of the laser reflected by the object to inspection in a direction different from the first optical path.

[0014] [The effects of the invention]

[0015] The defect inspection apparatus and method of the present invention, based on the first aspect, acquire an interference image representing the vibration state of the object under inspection as observed from the direction along the first optical path by using interference light from a laser beam reflected from a measuring unit that measures the interference light. Furthermore, the defect inspection apparatus and method of the present invention, based on the first aspect, acquire an interference image representing the vibration state of the object under inspection as observed from the direction along the second optical path by using interference light from a laser beam reflected from the object under inspection in a direction different from the first optical path. Thus, it is possible to acquire both an interference image representing the vibration state of the object under inspection as observed from the direction along the first optical path reflected from the measuring unit that measures the interference light, and an interference image representing the vibration state of the object under inspection as observed from the direction along the second optical path reflected in a direction different from the first optical path. Therefore, interference images representing the vibration state of the object under inspection can be acquired from two different directions without changing the angle of the object under inspection relative to the measuring unit. Therefore, the displacement of the vibration state of the object under inspection can be obtained from multiple directions, thus allowing the observation of the displacement of the vibration state of cracks of various depths (shallow cracks or deep cracks, etc.). As a result, a defect inspection device and method can be provided that can easily determine the presence or absence of cracks of various depths without changing the angle of the object under inspection relative to the measuring unit.

[0016] In the conventional defect inspection apparatus described in Japanese Patent Application Publication No. 2017-219318, when inspecting defects over a large area along the curved surface (circumferential direction) of an inspection object having a cylindrical or other curved surface, it is necessary to rotate the inspection object or change the position of the displacement measuring unit, and to perform multiple measurements along the direction (circumferential direction) of the curved surface of the inspection object. Thus, when the inspection object has a curved surface, the following problem exists: it is difficult to easily expand the measurement area for determining the presence or absence of defects without changing the position of the inspection object and the measuring unit. The present invention also solves this problem. That is, in the defect inspection apparatus and defect inspection method based on the first aspect and the second aspect of the present invention, since interference images representing the vibration state of the inspection object observed from the direction along the first optical path and interference images representing the vibration state of the inspection object observed from the direction along the second optical path are acquired, interference images representing the vibration state can be acquired from two different directions. Therefore, interference images representing the vibration state of the object under inspection can be acquired from multiple directions relative to the curved surface of the object. This differs from acquiring an interference image representing the vibration state of an object with a curved surface from only one direction, allowing for an expansion of the measurement area for determining the presence or absence of defects without changing the positions of the object under inspection and the measuring unit. Consequently, a defect inspection apparatus and method can be provided that, when the object under inspection has a curved surface, allows for easy expansion of the measurement area for determining the presence or absence of defects without changing the positions of the object under inspection and the measuring unit. Attached Figure Description

[0017] Figure 1 This is a schematic diagram showing the overall structure of the defect inspection device based on the first embodiment of the present invention.

[0018] Figure 2 This diagram illustrates an example of the convergence and divergence of light in relation to the imaging of light reflected in the direction along the first optical path, as shown in the first embodiment.

[0019] Figure 3 This diagram illustrates an example of the convergence and divergence of light in relation to the capture of light reflected in the direction along the second optical path, as described in the first embodiment.

[0020] Figure 4 This is a diagram showing the light-receiving area of ​​the image sensor based on the first embodiment.

[0021] Figure 5 This is a diagram showing an example of an interferometric image based on the first embodiment.

[0022] Figure 6This is a diagram showing the vibration caused by a relatively deep crack in the object under inspection, which is under vibration.

[0023] Figure 7 This is a diagram showing the vibration caused by a relatively shallow crack in the object under inspection, which is in a state of vibration.

[0024] Figure 8 This is a diagram representing an example of a synthetic image based on the first embodiment.

[0025] Figure 9 This is a first schematic diagram showing the overall structure of a defect inspection device based on a second embodiment of the present invention, and is a diagram showing an example of the convergence and divergence state of light related to the imaging of light reflected in the direction along the first optical path.

[0026] Figure 10 This is a second schematic diagram showing the overall structure of a defect inspection device based on a second embodiment of the present invention, and is a diagram showing an example of the convergence and divergence state of light related to the imaging of light reflected in the direction along the second optical path.

[0027] Figure 11 This is a diagram showing the light-receiving area of ​​the image sensor based on the second embodiment.

[0028] Figure 12 This is a diagram showing an example of a first interferometric image based on a second embodiment.

[0029] Figure 13 This is a diagram showing an example of a second interferometric image based on the second embodiment.

[0030] Figure 14 This is a diagram representing an example of a synthetic image based on the second embodiment.

[0031] Figure 15 This is a schematic diagram showing the overall structure of a defect inspection device based on a third embodiment of the present invention.

[0032] Figure 16 This is a schematic diagram showing the first and second optical paths reflected from the object being inspected in the defect inspection apparatus based on the third embodiment of the present invention.

[0033] Figure 17 This is a diagram showing the light-receiving area of ​​an image sensor based on the third embodiment.

[0034] Figure 18 This diagram illustrates an example of the convergence and divergence of light in relation to the imaging of light reflected in the direction along the first optical path in the third embodiment.

[0035] Figure 19This diagram illustrates an example of the convergence and divergence of light in relation to the imaging of light reflected in the direction along the second light path in the third embodiment.

[0036] Figure 20 This diagram illustrates an example of image correction and image linking processing for interferometric images based on the third embodiment.

[0037] Figure 21 This is a schematic diagram showing the first, second, third, and fourth optical paths reflected from the object being inspected by the defect inspection apparatus according to the fourth embodiment of the present invention.

[0038] Figure 22 This is a diagram showing the light-receiving area of ​​an image sensor based on the fourth embodiment.

[0039] Figure 23 This is a diagram showing an example of an interferometric image based on the fourth embodiment.

[0040] Figure 24 This diagram illustrates an example of image correction and image linking processing for interferometric images based on the fourth embodiment.

[0041] Figure 25 This is a first schematic diagram showing the overall structure of a defect inspection apparatus based on a fifth embodiment of the present invention, and is a diagram showing an example of the convergence and divergence state of light related to the imaging of light reflected in the direction along the first optical path.

[0042] Figure 26 This is a second schematic diagram showing the overall structure of the defect inspection apparatus based on the fifth embodiment of the present invention, and is a diagram showing an example of the convergence and divergence state of light related to the imaging of light reflected in the direction along the second optical path.

[0043] Figure 27 This is a schematic diagram showing the first and second optical paths reflected from the object being inspected by the defect inspection apparatus according to the fifth embodiment of the present invention.

[0044] Figure 28 This is a diagram showing the light-receiving area of ​​the image sensor based on the fifth embodiment.

[0045] Figure 29 The first figure is an example of an interferometric image based on the fifth embodiment.

[0046] Figure 30 The second figure shows an example of an interferometric image based on the fifth embodiment.

[0047] Figure 31This diagram illustrates an example of corrected image processing and image linking processing for interferometric images based on the fifth embodiment.

[0048] Figure 32 This is a diagram schematically showing the overall structure of the defect inspection device based on the first modified example. Detailed Implementation

[0049] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0050] [First Implementation Form]

[0051] Reference Figures 1 to 8 The structure of the defect inspection device 100 based on the first embodiment will be described.

[0052] (Structure of the defect inspection device)

[0053] like Figure 1 As shown, the defect inspection apparatus 100 based on the first embodiment includes a vibrator 1, a laser illumination 2, and a measuring unit 3. Furthermore, the vibrator 1 is an example of the "excitation unit" in the claims, and the laser illumination 2 is an example of the "illumination unit" in the claims.

[0054] Furthermore, the defect inspection device 100 includes an optical system 4, a control unit 5, a signal generator 6, and a display unit 7. Additionally, the control unit 5 is an example of the "image processing unit" mentioned in the claims.

[0055] The defect inspection apparatus 100 is configured to acquire an interference image 70 representing the vibration state of the inspection object 8 (described later), and to determine whether the inspection object 8 has a defect (defect 90). The acquired interference image 70 representing the vibration state of the inspection object 8 is displayed on the display unit 7. Furthermore, the display unit 7 includes, for example, a liquid crystal display or an organic electroluminescent (EL) display. The display unit 7 is connected to the control unit 5, for example, via a video interface such as HDMI (registered trademark).

[0056] The object of inspection 8 is a plate-shaped component. For example, the object of inspection 8 is a coated steel plate. Defects 90 (cracks 91 and 92) are found in the object of inspection 8. Furthermore, crack 91 is a deeper crack, and crack 92 is a shallower crack.

[0057] The vibrator 1 and laser illumination 2 of the defect inspection device 100 are respectively connected to the signal generator 6 via cables.

[0058] The vibrator 1 receives an AC signal from the signal generator 6 and excites elastic waves onto the object under inspection 8. The vibrator 1 is configured to contact the object under inspection 8 and convert the AC signal from the signal generator 6 into mechanical vibration, thereby imparting elastic wave vibration to and exciting the object under inspection 8.

[0059] Laser illumination 2 receives an electrical signal from signal generator 6 and illuminates the object with a laser. Laser illumination 2 includes a laser source (not shown) and an illumination lens. Laser illumination 2 is configured to illuminate the object 8 under inspection, which is in a state of elastic wave vibration excited by vibrator 1. The illumination lens amplifies the laser light emitted from the laser source to cover the entire measurement area of ​​the surface 80 of the object 8.

[0060] Furthermore, the vibrator 1, laser illumination 2, optical system 4, and the object to be inspected 8 are housed within a box-shaped housing 40. This blocks the influence of external light. Additionally, to allow the laser reflected from the object to be inspected 8 to enter the measuring unit 3, an opening (not shown) is provided at the corresponding location of the measuring unit 3 within the housing 40. Alternatively, the vibrator 1, laser illumination 2, optical system 4, and the object to be inspected 8 may not be housed within the box-shaped housing 40. That is, the defect inspection device 100 may not include the box-shaped housing 40. Furthermore, the laser illumination 2 is positioned between the surface 80 of the object to be inspected 8 and the measuring unit 3.

[0061] The measuring unit 3 includes a beam splitter 31, a phase shifter 32, a first reflecting mirror 33, a second reflecting mirror 34, a condenser lens 35, and an image sensor 36. The measuring unit 3 includes a speckle shear interferometer. The measuring unit 3 is configured to change the phase of the laser light reflected by the object under inspection 8, cause the laser light before and after the phase change to interfere with each other, and measure the interference light. Furthermore, the image sensor 36 is an example of the "image capturing unit" in the claims.

[0062] Beam splitter 31 is a semi-reflective mirror positioned at the point where the laser reflected from the surface 80 of the object being inspected is incident.

[0063] The first reflector 33 is configured such that it forms a 45-degree angle with respect to the reflecting surface of the beam splitter 31 in the optical path of the laser reflected by the beam splitter 31.

[0064] The second reflector 34 is configured such that it is slightly tilted at an angle of 45 degrees relative to the reflecting surface of the beam splitter 31 in the optical path of the laser transmitted through the beam splitter 31.

[0065] The phase shifter 32 is disposed between the beam splitter 31 and the first reflector 33, and is configured to change (shift) the phase of the transmitted laser under the control of the control unit 5.

[0066] Image sensor 36 has a light receiving area 30 for receiving the interference light of the laser beam after interference from measurement unit 3 (see reference). Figure 4 The light-receiving area 30 has multiple pixels (photodiodes). The image sensor 36 includes, for example, a complementary metal-oxide-semiconductor (CMOS) image sensor or a charge-coupled device (CCD) image sensor.

[0067] The image sensor 36 is positioned on the optical path of the laser light that is reflected by the first mirror 33 after being reflected by the beam splitter 31 and then transmitted through the beam splitter 31, and the laser light that is reflected by the second mirror 34 after being transmitted through the beam splitter 31 and then reflected by the beam splitter 31.

[0068] A focusing lens 35 is disposed between the beam splitter 31 and the image sensor 36 to focus the laser light transmitted through the beam splitter 31 and the laser light reflected by the beam splitter 31.

[0069] The optical system 4 includes multiple (two) mirrors (mirror 41 and mirror 42).

[0070] In the first embodiment, the optical system 4 (reflector 41 and reflector 42) is located outside the first light path 21 reflected from the object under inspection 8 toward the measuring unit 3, and is configured to guide the laser light passing through the second light path 22 toward the measuring unit 3.

[0071] An optical system 4 is positioned between the measuring unit 3 and the object to be inspected 8. The optical system 4 is configured to reflect laser light from a second optical path 22, which is reflected in a direction different from the first optical path 21, using a mirror 41 and then a mirror 42, so that the laser light from the second optical path 22 is incident on the measuring unit 3. This guides the laser light from the second optical path 22, which is reflected in a direction different from the first optical path 21, towards the measuring unit 3. Furthermore, in... Figure 1 In the diagram, the optical axes of the two systems on the first optical path 21 side are represented by dashed lines, and the optical axes of the two systems on the second optical path 22 side are represented by dashed lines. Furthermore, Figure 2 This illustrates an example of the convergence and divergence of light related to the imaging of light reflected along the direction of the first optical path 21. Additionally, Figure 3 This illustrates an example of the convergence and divergence of light in relation to the imaging of light reflected in the direction along the second optical path 22.

[0072] Furthermore, in the first embodiment, the laser illumination 2 and the optical system 4 are arranged in a direction orthogonal to the direction facing the surface 80 of the object under inspection 8 and the measuring unit 3, separated by the first optical path 21. The laser illumination 2 and the optical system 4 are respectively configured such that the laser light irradiated by the laser illumination 2 does not directly irradiate the reflecting surfaces of the reflector 41 and the reflector 42 of the optical system 4.

[0073] Furthermore, the laser beam reflected from point A81 on the surface 80 of the object under inspection 8 toward the front of the measuring unit 3 in a direction orthogonal to the surface 80, passes through the first optical path 21, and is reflected by the first reflecting mirror 33. Figure 2 The dashed line) and the laser light reflected from point B82 on the surface 80 of the object under inspection 8 toward the front of the measuring unit 3 in a direction orthogonal to the surface 80, passing through the first optical path 21 and being reflected by the second reflecting mirror 34. Figure 2 The dotted lines interfere with each other and are incident on the same part of the light receiving area 30 of the image sensor 36.

[0074] Additionally, the laser light reflected from point A81 on the surface 80 of the object being inspected 8 in an inclined direction relative to the surface 80 of the object being inspected 8, passes through the second optical path 22, and is reflected by the first reflecting mirror 33 ( Figure 3 The dashed line) and the laser light reflected from point B82 on the surface 80 of the object being inspected 8 in an inclined direction relative to the surface 80 of the object being inspected 8, passing through the second optical path 22 and being reflected by the second reflecting mirror 34. Figure 3 The dotted lines interfere with each other and are incident on the same part of the light receiving area 30 of the image sensor 36.

[0075] Furthermore, the following example is shown: a point on one side (optical system 4 side) of the surface 80 of the object to be inspected, where the laser is reflected in the frontal direction in the first optical path 21, is the same point (point A 81) as a point on one side (optical system 4 side) of the surface 80 of the object to be inspected, where the laser is reflected in the oblique direction in the second optical path 22. However, they may not be the same point. Additionally, the following example is shown: a point on the other side (vibrator 1 side) of the surface 80 of the object to be inspected, where the laser is reflected in the frontal direction in the first optical path 21, is the same point (point B 82) as a point on the other side (vibrator 1 side) of the surface 80 of the object to be inspected, where the laser is reflected in the oblique direction in the second optical path 22. However, they may not be the same point.

[0076] The control unit 5 uses an actuator (not shown) to operate the phase shifter 32 located in the measuring unit 3, thereby changing the phase of the transmitted laser.

[0077] Therefore, the phase difference between the laser reflected at point A81 on the surface 80 of the object under inspection 8 and the laser reflected at point B82 on the surface 80 of the object under inspection 8 and the laser reflected at point B82 on the surface 80 of the object under inspection 8 and the laser reflected at point B82 on the surface 80 of the object under inspection 8 and the laser reflected at point B82 on the surface 80 of the object under inspection 8 and the laser reflected at point B82 on the surface 80 of the object under inspection 8 and the laser reflected at point A81 ... A81 on the surface 80 of the object under inspection 8 and the laser reflected at point B82 on the surface 80 of the object under inspection 8 and the laser reflected at point B82 on the surface 80 of the object under inspection 8 and the laser reflected at point A81 on the surface 80 of the object under inspection 8 and the laser reflected at point B82 on the surface 80 of the object under inspection 8 and the laser reflected at point B82 on the surface 80 of the object under inspection 8 and the laser reflected at point B82 on the surface 80 of the object under inspection 8 and the laser reflected at point B82 on the surface 80 of the object under inspection 8 and the laser reflected at point B82 on the surface 80 of the object under inspection 8

[0078] Furthermore, the phase difference between the laser reflected at point A81 on the surface 80 of the object being inspected and passing through the second optical path 22 and the laser reflected at point B82 on the surface 80 of the object being inspected and passing through the second optical path 22 changes. Moreover, each detection element in the light receiving area 30 of the image sensor 36 detects the intensity of the interference light after the laser reflected at point A81 and passing through the second optical path 22 interferes with the laser reflected at point B82 and passing through the second optical path 22.

[0079] Thus, in the first embodiment, the image sensor 36 is configured to capture the interference light of the laser beam reflected from the object under inspection 8 toward the measuring unit 3 via the first optical path 21, and the interference light of the laser beam reflected from the object under inspection 8 toward the second optical path 22, which is reflected by the optical system 4 toward the measuring unit 3 in a direction different from the first optical path 21. That is, the common image sensor (image sensor 36) is used to capture the interference light of the laser beam reflected from the object under inspection 8 toward the measuring unit 3 via the first optical path 21, and the interference light of the laser beam reflected from the object under inspection 8 toward the second optical path 22, which is reflected by the optical system 4 in a direction different from the first optical path 21.

[0080] The control unit 5 includes a central processing unit (CPU), read-only memory (ROM), and random access memory (RAM). The control unit 5 is, for example, a personal computer. Alternatively, the control unit 5 may include non-volatile memory, a hard disk drive (HDD), or a solid-state drive (SSD).

[0081] In the first embodiment, the measuring unit 3 is configured to acquire an interference image (first interference image 71, described later) representing the vibration state of the object under inspection 8 as observed along the first optical path 21, based on interference light from the laser illumination 2 that is irradiated and reflected from the object under inspection 8 toward the measuring unit 3 via the first optical path 21. Furthermore, the direction of displacement of the vibration state acquired (observed) from the interference image (first interference image 71, described later) representing the vibration state of the object under inspection 8 as observed along the first optical path 21 is a direction that bisects the angle between the laser illumination 2 and the first optical path 21 (measuring unit 3 or beam splitter 31) relative to the object under inspection 8. In the first embodiment, the defect inspection apparatus 100 (measuring unit 3) acquires an interference image representing the vibration state of the object under inspection 8 in a direction substantially perpendicular to the surface 80 of the object under inspection 8, based on interference light from the laser passing through the first optical path 21.

[0082] Specifically, the measuring unit 3 is configured to acquire an interference image (first interference image 71) representing the vibration state of the object 8 as observed from the front direction (along the direction of the first optical path 21) based on interference light from a laser beam reflected from the object 8 in a direction orthogonal to the surface 80 of the object 8 and directed toward the measuring unit 3 without passing through the optical system 4. In other words, the measuring unit 3 is configured to acquire the first interference image 71 based on interference light from a laser beam reflected directly from the object 8 toward the measuring unit 3 in a direction orthogonal to the surface 80 of the object 8.

[0083] Furthermore, in the first embodiment, the measuring unit 3 is configured to acquire an interference image (second interference image 72, described later) representing the vibration state of the object under inspection as observed along the second optical path 22, based on interference light from the laser illumination 2 that is reflected from the object under inspection 8 in a direction different from the first optical path 21 via the second optical path 22. Moreover, the direction of displacement of the vibration state acquired (observed) from the interference image (second interference image 72, described later) representing the vibration state of the object under inspection 8 as observed along the second optical path 22 is the direction that bisects the angle between the laser illumination 2 and the second optical path 22 (reflector 41) relative to the object under inspection 8. In the first embodiment, the defect inspection apparatus 100 (measuring unit 3) acquires an interference image representing the vibration state of the object under inspection 8 in a direction inclined relative to the direction perpendicular to the surface 80 of the object under inspection 8 (the direction between the direction perpendicular to the surface 80 of the object under inspection 8 and the direction parallel to the surface 80) based on interference light from the laser passing through the second optical path 22.

[0084] Specifically, the measuring unit 3 is configured to acquire an interference image (second interference image 72) representing the vibration state of the object 8 as observed from the tilt direction, based on the interference light of the laser beam that passes through the second optical path 22, which is the second optical path 22 that reflects light in a tilted direction different from the first optical path 21 towards the measuring unit 3, relative to the common surface (surface 80) of the object 8 to which the laser beam is reflected towards the measuring unit 3 by the optical system 4 (reflector 41 and reflector 42). In other words, the measuring unit 3 is configured to acquire the second interference image 72 based on the interference light of the laser beam that passes through the second optical path 22 guided towards the measuring unit 3 by the optical system 4. Furthermore, the tilt angle of the second optical path 22 relative to the surface 80 of the object 8 is at least less than 60°. For example, the tilt angle of the second optical path 22 relative to the surface 80 of the object 8 is approximately 30° to 45°. That is, the measuring unit 3 is configured to acquire an interference image (second interference image 72) representing the vibration state of the object under inspection 8 as observed from an angle of at least less than 60°, for example, an angle of about 30° to 45°, relative to the surface 80 of the object under inspection 8 (along the direction of the surface 80 of the object under inspection 8).

[0085] (Structures related to the acquisition of the first and second interferometric images)

[0086] The measuring unit 3 is configured such that it measures light in region 30a of the light receiving area 30 of the image sensor 36 (refer to...). Figure 4 The first interference image 71 is acquired by receiving interference light reflected from the surface 80 of the object under inspection 8 after passing through the first optical path 21. Furthermore, the measurement unit 3 is configured to measure the light in region 30b of the light receiving area 30 of the image sensor 36 (see reference 30b). Figure 4 The system receives interference light from the laser beam reflected from the surface 80 of the object under inspection 8 and passing through the second optical path 22, thereby acquiring a second interference image 72.

[0087] That is, in the first embodiment, the measuring unit 3 is configured to receive the interference light of the laser light reflected from the common surface (surface 80) of the object under inspection 8 through the first optical path 21 and the laser light through the second optical path 22 in each of the multiple regions (region 30a and region 30b) of the light receiving region 30, which are divided into multiple regions corresponding to the interference light of the laser light passing through the first optical path 21 and the interference light of the laser light passing through the second optical path 22, and simultaneously acquire the first interference image 71 and the second interference image 72.

[0088] like Figure 5As shown, the interference image 70 acquired based on the interference light received in the light receiving region 30 of the image sensor 36 includes: a first interference image 71, based on region 30a of the light receiving region 30 (refer to...). Figure 4 The interference light received from the laser passing through the first optical path 21 is used to acquire the second interference image 72, based on region 30b of the light receiving region 30 (refer to...). Figure 4 It is obtained by receiving the interference light of the laser that has passed through the second optical path 22.

[0089] Here, in the cracked 91 (see reference) Figure 1 In cases of deep cracks, such as Figure 6 As shown, by exciting elastic wave vibrations onto the object under inspection 8, vibrations are generated at the crack 91 of the object under inspection 8 in the vertical direction (the direction orthogonal to the surface 80 of the object under inspection 8) and the in-plane direction (the opening and closing direction of the crack) that are different from the normal vibration of the object under inspection 8. Therefore, a discontinuity in the vertical and in-plane vibration states is generated at the crack 91 of the object under inspection 8. On the other hand, at crack 92 (see reference...) Figure 1 In cases of relatively shallow cracks, such as Figure 7 As shown, by exciting elastic wave vibrations onto the object under inspection 8, vibrations are generated at the crack 92 of the object under inspection 8 in the in-plane direction (the opening and closing direction of the crack 92), which are different from the normal vibrations of the object under inspection 8. Therefore, a discontinuity in the in-plane vibration state is generated at the crack 92 of the object under inspection 8.

[0090] First interferogram 71 (reference) Figure 5 The first interference image 71 is an interference pattern representing the vibration state of the object under inspection 8 as observed from the front direction (along the direction of the first optical path 21), based on the interference light of the laser passing through the first optical path 21. The first optical path 21 is a light path reflected from the object under inspection 8 in a direction orthogonal to the surface 80 of the object under inspection 8 (the direction in which the surface 80 of the object under inspection 8 faces the measuring unit 3). That is, the first interference image 71 (refer to...) Figure 5 The first interference pattern 71 is an interference image representing the vibration state of the object 8 in the vertical direction (orthogonal to the surface 80 of the object 8 under inspection). Therefore, in the first interference pattern 71, the displacement 91a (the vertical displacement of the vibration state) caused by a relatively deep crack can be easily detected. That is, as... Figure 5 As shown, in the first interference image 71, cracks such as 91 (see reference) can be easily detected. Figure 1 The displacement of the vibration state caused by such deep cracks is 91a (displacement in the vertical direction of the vibration state).

[0091] Additionally, the second interferogram 72 (reference) Figure 5 The interference image represents the vibration state of the object 8 as observed from the tilt direction, based on the interference light of the laser beam reflected by the second optical path 22 through the surface 80 of the object 8 in an inclined direction. Therefore, the vibration state of the object 8 can be represented by light from sources such as crack 92 (see reference). Figure 1 The displacement of the vibration state caused by relatively shallow cracks (the displacement in the in-plane direction of the vibration state) is considered as the displacement in the tilt direction 92b (refer to...). Figure 5 Therefore, compared to the first interferometric image 71, the displacement of the vibration state caused by the relatively shallow cracks (the in-plane displacement of the vibration state) can be easily detected in the second interferometric image 72. That is, as... Figure 5 As shown, in the second interferometric image 72, in addition to easily detecting cracks such as 91 (see reference) Figure 1 In addition to the displacement 91a (displacement in the vertical direction of the vibration state) caused by relatively deep cracks such as those found in cracks 92 (see reference), it is also possible to easily detect the displacement caused by cracks such as those found in cracks 92 (see reference). Figure 1 The displacement of the vibration state caused by such shallow cracks (the displacement in the in-plane direction of the vibration state) is referred to as displacement 92b.

[0092] In the first embodiment, the optical system 4 includes an even number (two) of mirrors (mirror 41 and mirror 42). The laser light passing through the first optical path 21 is measured in the measurement unit 3 after passing through mirrors 41 and 42. Therefore, since the second interference image 72 can be acquired without reversing its left-right position relative to the first interference image 71, display and image synthesis processing can be performed without reversing the second interference image 72 through image processing.

[0093] Furthermore, the control unit 5 is configured to acquire the first interferometric image 71 (reference image 71). Figure 5 ) and the second interferogram 72 (refer to) Figure 5 The composite image 73 (refer to) is obtained by performing composite processing. Figure 8 The first interference image 71 represents the vibration state observed from the front direction of the measuring unit 3 along a direction orthogonal to the surface 80 of the object under inspection 8, and the second interference image 72 represents the vibration state observed from an oblique direction relative to the surface 80 of the object under inspection 8 in the measuring area of ​​the object under inspection 8. Furthermore, since the directions of displacement for acquiring the vibration state are different in the first interference image 71 and the second interference image 72, the aspect ratios of the images are different. Therefore, when the control unit 5 performs the composite processing of the first interference image 71 and the second interference image 72, it at least performs distortion correction (image correction processing) on ​​the second interference image 72.

[0094] For example, the control unit 5 performs distortion correction to make the second interferometric image 72 consistent with the first interferometric image 71. The control unit 5 corrects the distortion of the second interferometric image 72 (aspect ratio correction or trapezoidal correction) to make the first interferometric image 71 and the second interferometric image 72 consistent in the same measurement area (image area). Then, the control unit 5 or the user compares the defect location between the image obtained after correcting the second interferometric image 72 and the first interferometric image 71. Furthermore, the first interferometric image 71 (an image taken from the frontal direction) is not necessarily taken directly from the front (an image of the vibration state observed from the front), and sometimes some distortion may occur. In this case, image corrections (distortion corrections) such as aspect ratio correction and trapezoidal correction are also applied to the first interferometric image 71 (an image taken from the frontal direction). By performing this image correction processing, the defect inspection device 100 can synthesize images obtained from the vibration state observed from the front direction (vibration state in a direction approximately perpendicular to the surface 80 of the object under inspection) and images obtained from the vibration state observed from the oblique direction, under the same measurement area (shooting area) or positional relationship, through image comparison or analysis processing.

[0095] Alternatively, image correction can be performed only on the second interferometric image 72 (image taken in an oblique direction) based on the reference point (4 corners) data from the capture of the first interferometric image 71 and the second interferometric image 72. This allows for comparison of defect locations within the same measurement area (capture area) or positional relationship using the corrected second interferometric image 72 and the uncorrected first interferometric image 71 (image taken in a frontal direction). Furthermore, the correction method is not limited to the method described above, as long as it is used to combine the first interferometric image 71 and the second interferometric image 72 for distortion correction. In the defect inspection device 100, the images before correction (first interferometric image 71 and second interferometric image 72), the corrected image, and the composite image 73 are each stored in an internal or external memory (storage device) of the control unit 5. Moreover, the storage of these images can be determined by changes made by the user to whether each of the images before correction, the corrected image, and the composite image 73 is stored.

[0096] The control unit 5 controls the vibration of the vibrator 1 and the timing of laser irradiation by the laser illumination 2 via the signal generator 6. Simultaneously, while changing the phase shift, the measurement unit 3 captures (acquires) interference images 70 (first interference image 71 and second interference image 72). The control unit 5 changes the phase shift by λ / 4 each time. At each phase shift (0, λ / 4, λ / 2, 3λ / 4), the measurement unit 3 captures (acquires) a total of 37 images: 32 interference images 70 (first interference image 71 and second interference image 72) corresponding to the timing j (j = 0 to 7) of laser irradiation, and 5 images taken before and after each phase shift (0, λ / 4, λ / 2, 3λ / 4) at the time of lamp extinguishing. Furthermore, λ is the wavelength of the laser.

[0097] The control unit 5 processes the detection signals from each detection element of the light receiving area 30 of the image sensor 36 in the following order, and obtains a dynamic image (spatial distribution image of vibration state) representing the vibration state based on the interference image 70 (first interference image 71 and second interference image 72) and the image when the light is off.

[0098] The brightness value I of four images (each with the same laser irradiation timing j (j=0~7) and a phase shift difference of λ / 4 each time) is determined. j0 ~I j3 And using equation (1), the optical phase (the phase difference between the two optical paths when the phase shift is zero) Φ is calculated. j .

[0099] Φ j =-arctan{(I j3 -I j1 ) / (I j2 -I j0 )}…(1)

[0100] Using the least squares method to determine the optical phase Φ j By performing a sine wave approximation, the approximation coefficients A, θ, and C in equation (2) are obtained.

[0101] Φ j =Acos(θ+jπ / 4)+C=Be×p(jπ / 4)+C…(2)

[0102] Where B is the complex amplitude, as expressed in equation (3).

[0103] B=Ae×p(iφ): Complex amplitude…(3)

[0104] Here, the complex amplitude B is the basic image information (two-dimensional spatial information of the complex amplitude) used to output a dynamic image (spatial distribution image of vibration state) representing the vibration state of the measurement area of ​​the object under inspection 8. According to the approximation after removing the constant term C from equation (2), a dynamic image (30 to 60 frames) showing the change of light phase at each phase time ξ (0 ≦ ξ < 2π) of the vibration is constructed and output as a dynamic image (spatial distribution image of vibration state) representing the vibration state of the measurement area of ​​the object under inspection 8. The image used to output the dynamic image (spatial distribution image of vibration state) representing the vibration state can be an interference image 70 (first interference image 71 and second interference image 72) or a composite image 73. In addition, the control unit 5 can also output a dynamic image (spatial distribution image of vibration state) representing the vibration state using each of the first interference image 71 and the second interference image 72, and perform composite processing on the two dynamic images (spatial distribution images of vibration state) representing the vibration state output using each of the first interference image 71 and the second interference image 72.

[0105] Furthermore, in order to remove noise during the process, a spatial filter may be appropriately applied to the complex amplitude B. Additionally, the step size of the phase shift or the timing of laser irradiation (λ / 4 and T / 8 in the example, respectively, where T is the period of vibration) is not limited to this. In this case, the calculation formula becomes different from equations (1) to (3).

[0106] The control unit 5 applies a spatial filter to detect discontinuous areas of the vibration state as defects 90 in the object under inspection 8 based on the dynamic image representing the vibration state. In cases where the object under inspection 8 itself has a shape including unevenness, discontinuities in the vibration state may sometimes occur at the boundaries between planar and uneven portions. The shape information of the object under inspection 8 can also be considered when detecting defects 90 so that they are not detected as defects. Alternatively, the control unit 5 can also use information from interference light in the interference images 70 (first interference image 71 and second interference image 72), which are used to output the dynamic image representing the vibration state, to detect defects 90.

[0107] The control unit 5 controls the display unit 7 to display a dynamic image representing the vibration state. The display unit 7 displays a dynamic image representing the vibration state of the measurement area of ​​the object under inspection 8 based on the control of the control unit 5.

[0108] In addition, the control unit 5 performs the following control: displays the interference image 70 (first interference image 71 and second interference image 72) representing the vibration state of the object under inspection 8, or the composite image 73 obtained by composite processing, on the display unit 7. The display unit 7 displays the interference image 70 (first interference image 71 and second interference image 72) or the composite image 73 representing the vibration state of the object under inspection 8 based on the control of the control unit 5.

[0109] In addition, any one of the following can be switched and displayed on the display unit 7: a dynamic image representing the vibration state of the measurement area of ​​the object under inspection 8, an interference image 70 (first interference image 71 and second interference image 72), and a composite image 73. Alternatively, multiple images and dynamic images can be combined and displayed on the display unit 7.

[0110] (Effects of the first implementation)

[0111] In the first embodiment, the following effect can be obtained.

[0112] In the first embodiment, the defect inspection apparatus 100 and the defect inspection method acquire a first interference image 71 representing the vibration state of the object under inspection 8 as observed from the direction along the first optical path 21, based on interference light from a laser beam reflected by a measuring unit 3 that measures interference light. Furthermore, a second interference image 72 representing the vibration state of the object under inspection 8 as observed from the direction along the second optical path 22, based on interference light from a laser beam reflected by a laser beam reflected from the object under inspection 8 in a direction different from the first optical path 21, is acquired. Thus, both the first interference image 71 representing the vibration state of the object under inspection 8 as observed from the direction along the first optical path 21 reflected by the measuring unit 3 that measures interference light, and the second interference image 72 representing the vibration state of the object under inspection 8 as observed from the direction along the second optical path 22, can be acquired from two different directions, allowing interference images (first interference image 71 and second interference image 72) representing the vibration state of the object under inspection 8. Therefore, without changing the angle of the object under inspection 8 relative to the measuring unit 3, the displacement of the vibration state of the object under inspection 8 can be obtained from two different directions (two different directions) observed along the direction of the first light path 21 reflected towards the measuring unit 3 and along the direction of the second light path 22 reflected in a direction different from the first light path 21. Thus, the displacement of the vibration state of the object under inspection 8 observed from multiple directions can be obtained, and therefore the displacement of the vibration state of cracks of various depths (relatively shallow cracks or relatively deep cracks, etc.) can be observed. As a result, the presence or absence of cracks of various depths can be easily determined without changing the angle of the object under inspection 8 relative to the measuring unit 3.

[0113] Furthermore, in the defect inspection device 100 based on the first embodiment, the following further effects can be obtained by configuring it as follows.

[0114] Furthermore, in the defect inspection apparatus 100 of the first embodiment, as described above, the optical system 4 is configured to guide the laser light passing through the second optical path 22, which is reflected in a direction different from the first optical path 21, toward the measuring unit 3. Therefore, by guiding the laser light passing through the second optical path 22, which is reflected in a direction different from the first optical path 21, toward the measuring unit 3, the optical system 4 can easily acquire an interference image (second interference image 72) representing the vibration state of the object 8 under inspection based on the laser light passing through the second optical path 22. Additionally, since the optical system 4 guides the laser light passing through the second optical path 22 toward the measuring unit 3, both the laser light passing through the first optical path 21 and the laser light passing through the second optical path 22 can be incident on a common measuring unit (measuring unit 3). As a result, compared to the case where the measuring unit 3 is provided for each laser light passing through the first optical path 21 and the laser light passing through the second optical path 22, the increase in the number of parts and the enlargement of the apparatus can be suppressed.

[0115] Furthermore, in the defect inspection apparatus 100 of the first embodiment, as described above, it is configured to use a common image sensor (image sensor 36) to capture the interference light of the laser beam reflected from the object under inspection 8 toward the measuring unit 3 via the first optical path 21, and the interference light of the laser beam reflected from the object under inspection 8 toward the second optical path 22, which is reflected by the optical system 4 toward the measuring unit 3 via a direction different from the first optical path 21. Therefore, compared to the case where an image sensor (capturing unit) is provided corresponding to each of the interference light of the laser beam passing through the first optical path 21 and the interference light of the laser beam passing through the second optical path 22, the increase in the number of parts can be suppressed, and the structure of the apparatus can be simplified.

[0116] Furthermore, in the defect inspection apparatus 100 of the first embodiment, as described above, the measuring unit 3 is configured to acquire an interference image (first interference image 71) representing the vibration state of the inspection object 8 as observed from the front direction (along the direction of the first optical path 21) based on interference light reflected from the inspection object 8 in the front direction of the measuring unit 3, which is reflected from the inspection object 8 via the first optical path 21 without passing through the optical system 4. Thus, based on the interference image (first interference image 71) representing the vibration state of the inspection object 8 as observed from the front direction (along the direction of the first optical path 21), the displacement (displacement 91a) in the direction orthogonal to the surface 80 of the inspection object 8 can be acquired, and therefore the presence or absence of relatively deep cracks (cracks 91) can be determined. Furthermore, the measuring unit 3 is configured to acquire an interference image (second interference image 72) representing the vibration state of the object 8 as observed from the tilt direction, based on the interference light of the laser beam that passes through the second optical path 22, which is the laser beam reflected in the tilt direction relative to the common surface (surface 80) of the surface of the object 8 facing the measuring unit 3. Thus, based on the interference image (second interference image 72) representing the vibration state of the object 8 as observed from the tilt direction relative to the common surface (surface 80) of the object 8, the displacement along the direction (in-plane direction) of the surface 80 of the object 8 can be acquired as a displacement in the tilt direction (displacement 92a) biased towards the direction orthogonal to the surface 80 of the object 8. Therefore, the presence or absence of relatively shallow cracks (crack 92) can be determined. As a result, the presence or absence of relatively deep cracks (crack 91) can be easily determined without changing the position of the object 8, and the presence or absence of relatively shallow cracks (crack 92) can also be easily determined.

[0117] Furthermore, the defect inspection apparatus 100 in the first embodiment, as described above, is configured to simultaneously acquire a first interference image 71 and a second interference image 72 by receiving interference light from each of the interference light from the laser passing through the first optical path 21 and the laser passing through the second optical path 22 in each of the multiple regions (regions 30a and 30b) of the light receiving region 30, which are divided into multiple regions corresponding to the interference light from the laser passing through the first optical path 21 and the interference light from the laser passing through the second optical path 22. Thus, the first interference image 71 based on the interference light from the laser passing through the first optical path 21 and the second interference image 72 based on the interference light from the laser passing through the second optical path 22 can be acquired simultaneously, thereby shortening the inspection time for checking whether the object 8 has defects (defects 90).

[0118] Furthermore, in the defect inspection apparatus 100 of the first embodiment, as described above, the control unit 5 is configured to acquire a composite image 73 obtained by combining a first interference image 71 and a second interference image 72. The first interference image 71 represents the vibration state observed from the front direction of the measuring unit 3 along a direction orthogonal to the surface 80 of the object being inspected, and the second interference image 72 represents the vibration state observed from an inclined direction relative to the surface 80 of the object being inspected in the measuring area of ​​the object being inspected. Thus, the composite image 73 can simultaneously represent the displacement (displacement 91a and displacement 92a) of the vibration state observed from multiple directions, allowing the user to easily identify and confirm the presence or absence of cracks of various depths.

[0119] Furthermore, in the defect inspection apparatus 100 of the first embodiment, as described above, the control unit 5 is configured to at least correct the distortion of the second interference image 72. Therefore, by correcting the distortion of the second interference image 72 through the control unit 5, it is easy to compare defects (defects 90) between the first interference image 71 and the second interference image 72, whose displacement acquisition directions are different under vibration conditions, and to perform composite processing of the first interference image 71 and the second interference image 72 (acquisition of composite image 73).

[0120] [Second Implementation Form]

[0121] Reference Figures 9-14 The structure of the defect inspection device 200 based on the second embodiment will be described. Furthermore, in the figures, structural parts identical to those in the first embodiment are labeled with the same symbols. Figure 9 This illustrates an example of the convergence and divergence of light related to the imaging of light reflected in the direction along the first optical path 221. Additionally, Figure 10 This illustrates an example of the convergence and divergence of light in relation to the imaging of light reflected in the direction along the second optical path 222.

[0122] In the second embodiment, unlike the first embodiment which is configured to acquire the first interference image 71 and the second interference image 72 simultaneously, the first interference image 271 and the second interference image 272 are acquired by switching the interference light of the received laser.

[0123] In the defect inspection device 200, the optical system 204 includes a reflector 241 and a reflector 242. For example... Figure 9 and Figure 10 As shown, the optical system 204 is disposed between the measuring unit 3 and the object 8 in a direction facing the measuring unit 3 on the surface 80 of the object 8 being inspected. Furthermore, a portion of the optical system 204 (reflector 242) is disposed on the first optical path 221.

[0124] In the defect inspection apparatus 200 based on the second embodiment, the position of the optical system 204 within the housing 40 can be changed. The defect inspection apparatus 200 is configured such that, by changing the position of the optical system 204, the laser reflected from the surface 80 of the object to be inspected 8 and incident on the measuring unit 3 can be switched to a laser passing through the first optical path 221 and a laser passing through the second optical path 222.

[0125] Specifically, the defect inspection device 200 is configured to move (offset) the positions of reflectors 241 and 242 in a direction intersecting the direction of the measuring unit 3 and the object to be inspected 8 via an actuator (not shown). Thus, the defect inspection device 200 (measuring unit 3) is configured to switch between states such that the laser light passing through the first optical path 221 is incident on the measuring unit 3 (see reference 241) by moving the positions of reflectors 241 and 242. Figure 9 The optical system 204 (reflector 242) is disposed on the first optical path 221, and the laser light from the second optical path 222, which blocks the laser light passing through the first optical path 221 and guides the light through the optical system 204, is incident on the measuring unit 3 (see reference). Figure 10 Furthermore, the position switching of the optical system 204 can be performed by control executed by the control unit 5 or by user operation. Additionally, the defect inspection device 200 can also be configured to switch the laser incident on the measuring unit 3 into a laser passing through the first optical path 221 and a laser passing through the second optical path 222 by simply moving the position of the reflector 242. Furthermore, the angles of the reflectors 241 and 242 can also be changed using an actuator (not shown).

[0126] In addition, the measuring unit 3 includes a common image sensor (image sensor 236), which captures interference light of laser light reflected from the object under inspection 8 toward the measuring unit 3 via a first optical path 221 and interference light of laser light reflected from the object under inspection 8 toward a second optical path 222 in a direction different from the first optical path 221.

[0127] In the second embodiment, the system is configured to capture the interference light of the laser beam reflected from the object under inspection 8 toward the measuring unit 3 via a common image sensor (image sensor 236), which is reflected by the laser beam reflected from the object under inspection 8 toward the measuring unit 3 via the first optical path 221 and the interference light of the laser beam reflected from the object under inspection 8 toward the second optical path 222 in a direction different from the first optical path 221.

[0128] In the second embodiment, the measuring unit 3 is configured to measure by means of... Figure 11The interference light of the laser received in the common area (light receiving area 230) of the light receiving area of ​​the image sensor 236 shown is switched to the interference light of the laser reflected from the common surface (surface 80) of the object under inspection 8, which passes through the first optical path 221 and the interference light of the laser passing through the second optical path 222, thereby acquiring the first interference image 271 (see reference). Figure 12 ) and the second interferogram 272 (refer to) Figure 13 Each of the following. And the first interference pattern 271 (refer to...) Figure 12 Compared to the second interferogram 272 (reference), Figure 13 In addition to being able to easily detect cracks such as crazing 91 (refer to...), Figure 9 In addition to the displacement 91a (displacement in the vertical direction of the vibration state) caused by relatively deep cracks, it is also possible to easily detect the displacement caused by cracks 92 (see reference). Figure 9 The displacement 92a (displacement in the in-plane direction of the vibration state) is caused by relatively shallow cracks. Furthermore, similar to the first embodiment, the first interference pattern 271 (referencing...) Figure 12 The direction of displacement of the vibration state obtained (observed) is the direction that bisects the angle between the laser illumination 2 and the first optical path 221 (measuring unit 3 or beam splitter 31) relative to the object under inspection 8. Additionally, the second interference image 272 (referencing...) Figure 13 The direction of displacement of the vibration state obtained (observed) becomes the direction that bisects the angle between the laser illumination 2 and the second optical path 222 (reflector 241) relative to the object under inspection 8.

[0129] Furthermore, the control unit 5 is configured to acquire the first interferometric image 271 (refer to...) Figure 12 ) and the second interferogram 272 (refer to Figure 13 The composite image 273 obtained by performing composite processing (refer to) Figure 14The first interference image 271 represents the vibration state observed from the front direction of the measuring unit 3 along a direction orthogonal to the surface 80 of the object under inspection 8, and the second interference image 272 represents the vibration state observed from an inclined direction relative to the surface 80 of the object under inspection 8 in the measuring area of ​​the object under inspection 8. Furthermore, as described above, the first interference image 271 and the second interference image 272 have different aspect ratios due to the different directions of displacement acquisition. Therefore, before the synthesis process of the first interference image 271 and the second interference image 272, or before the comparison of the first interference image 271 and the second interference image 272, the control unit 5 performs distortion correction (image correction processing) on ​​at least the second interference image 272. Furthermore, the distortion correction (image correction processing) for the first interference image 271 and the second interference image 272 is performed in the same manner as described in the first embodiment. Additionally, the saving (storage) of the images before correction (first interference image 271 and second interference image 272), the corrected image, and the synthesized image 73 is also performed in the same manner as in the first embodiment.

[0130] Furthermore, the other structures of the second embodiment are the same as those of the first embodiment.

[0131] (Effects of the second implementation)

[0132] In the second embodiment, the following effect can be obtained.

[0133] Similar to the first embodiment, in the second embodiment, the defect inspection device 200 and the defect inspection method can easily determine whether there are cracks of various depths (deeper cracks or shallower cracks, etc.) without changing the angle of the object under inspection 8 relative to the measuring unit 3.

[0134] Furthermore, in the defect inspection device 200 based on the second embodiment, the following further effects can be obtained by configuring it as follows.

[0135] Furthermore, in the defect inspection apparatus 200 of the second embodiment, as described above, the measuring unit 3 is configured to acquire a first interference image 271 and a second interference image 272 by switching the interference light of the laser received in the common area (light receiving area 230) of the light receiving area of ​​the image sensor 236 (imaging unit) to interference light of the laser reflected from the common surface (surface 80) of the object under inspection through the first optical path 221 and interference light of the laser through the second optical path 222. Thus, by switching the interference light of the laser received in the common area (light receiving area 230) of the light receiving area of ​​the image sensor 236 to acquire a first interference image 271 and a second interference image 272, the measuring unit 3 can acquire interference light of the laser through the first optical path 221 and interference light of the laser through the second optical path 222 without dividing the light receiving area 230 of the image sensor 236 into multiple areas. As a result, compared to the case where the light receiving area 230 of the image sensor 236 is divided into multiple areas to simultaneously receive both the interference light of the laser passing through the first optical path 221 and the interference light of the laser passing through the second optical path 222, the interference light of the laser passing through the first optical path 221 and the interference light of the laser passing through the second optical path 222 can be acquired in a wider area (light receiving area). Therefore, the first interference image 271 and the second interference image 272 can be acquired in a wider measurement area.

[0136] Furthermore, the other effects of the second embodiment are the same as those of the first embodiment.

[0137] [Third Implementation Form]

[0138] Reference Figures 15-20 The structure of the defect inspection device 300 based on the third embodiment will be described. Furthermore, in the figures, structural parts identical to those in the first and second embodiments are labeled with the same symbols.

[0139] Unlike the first embodiment where the inspected object 8 is a plate-shaped component, such as Figure 15 and Figure 16 As shown, the inspection object 308 in the third embodiment is an object having a curved surface 380. The inspection object 308 may, for example, be an object having a cylindrical or cylindrical shape. The defect inspection device 300 is configured to acquire an interference image 370 (see below) representing the vibration state of the inspection object 308. Figure 20 ), and constitutes a determination of whether the inspected object 308 has defects 390 (refer to Figure 16 ) to make a judgment. Furthermore, in Figure 15 In the diagram, the optical axes of the two systems on the first optical path 321 side are represented by dashed lines, and the optical axes of the two systems on the second optical path 322 side are represented by dashed lines.

[0140] In addition, such as Figure 15 As shown, the defect inspection apparatus 300 also includes a reflector 320 that reflects the laser light irradiated by the laser illumination 2. Furthermore, the laser illumination 2 and the reflector 320 are arranged with the object to be inspected 308 in between. By reflecting the laser light irradiated by the laser illumination 2 through the reflector 320, the laser light irradiated by the laser illumination 2 can reach not only the side of the object to be inspected facing the laser illumination 2 (surface side), but also the side of the object to be inspected opposite to the side facing the laser illumination 2 (back side).

[0141] In the third embodiment, the optical system 304 includes a reflector 341, a reflector 342, and a lens 343. Furthermore, the optical system 304 is located outside the first optical path 321 and is configured to guide the laser light reflected from a measurement area (different from the measurement area of ​​the inspected object 308 with a curved surface 380) that is reflected from the first optical path 321 facing the measurement unit 3, through the second optical path 322, towards the measurement unit 3.

[0142] Specifically, the optical system 304 reflects laser light from a measurement area different from the measurement area of ​​the object 308 being inspected (which is reflected towards the first optical path 321) that has passed through the second optical path 322. This laser light is then reflected by a mirror 341 and further reflected by a mirror 342. Furthermore, the optical system 304 is configured such that a lens 343 refracts the laser light further reflected by the mirror 342 and passing through the second optical path 322 before it is incident on the measurement unit 3. This guides the laser light from the second optical path 322, which is reflected in a direction different from the first optical path 321, towards the measurement unit 3.

[0143] Furthermore, the measuring unit 3 is configured to acquire interference images 370 representing the vibration state in multiple measuring areas of the object under inspection 308. Specifically, the measuring unit 3 is configured to acquire interference images 370 representing the vibration state in the area facing the front side of the measuring unit 3 towards the laser reflected from the first optical path 321 and in the area facing the side side of the laser reflected from the second optical path 322 (see reference). Figure 20 ).

[0144] like Figure 17As shown, the measurement unit 3 receives interference beams of laser light reflected from different measurement areas of the object under inspection 308 in each of the multiple regions (regions 330a and 330b) of the light receiving region 330 of the image sensor 336, which are divided into multiple regions corresponding to the interference beams of laser light reflected from the first optical path 321 and the second optical path 322, respectively. Thus, the measurement unit 3 is configured to simultaneously acquire interference images 371 and 372, representing the vibration states of the different measurement areas of the object under inspection 308 having a curved surface 380. In other words, the defect inspection device 300 is configured to simultaneously acquire interference images 371 and 372 corresponding to each interference beam of laser light reflected from the object under inspection 308 along multiple directions (two directions).

[0145] like Figure 17 As shown, the image sensor 336 has a light-receiving region 330 (regions 330a and 330b) that receives the interference light of the laser beam after interference from the measurement unit 3. The measurement unit 3 is configured to receive the interference light from the laser beam after interference from the measurement unit 3 in region 330a (see reference 330b) of the light-receiving region 330 of the image sensor 336. Figure 17 ) Receives laser light reflected from the object under inspection 308 along the direction opposite to the measuring unit 3 via the first optical path 321 (see reference). Figure 18 The interference light is used to obtain an interference image 371. Furthermore, Figure 18 An example of the convergence and divergence of light related to the imaging of light reflected in the direction along the first optical path 321 is shown.

[0146] Furthermore, the measuring unit 3 is configured to pass through region 330b of the light receiving area 330 of the image sensor 336 (refer to...) Figure 17 ) Receives laser light reflected from the object under inspection 308 along a direction orthogonal to the direction opposite to the measuring unit 3 via a second optical path 322 (see reference). Figure 19 The respective interfering beams of each light source are used to obtain an interference image 372. Furthermore, Figure 19 An example of the convergence and divergence of light related to the imaging of light reflected in the direction along the second optical path 322 is shown.

[0147] In the third embodiment, the control unit 5 is configured to correct the length of the acquired interference image 370 representing the vibration state of the object under inspection 308, at least in the direction along the surface 380 of the object under inspection 308, based on the curvature of the surface 380 of the object under inspection 308.

[0148] In addition, in the third embodiment, the control unit 5 is configured to continuously connect the interference images 370 representing the vibration states of multiple measurement areas in the direction along the curved surface 380 of the object under inspection 308.

[0149] Specifically, the control unit 5 corrects the lengths of the interferograms 371 and 372 along the direction of the surface 380 of the object 308 in the pre-acquired measurement area (image correction). Simultaneously, the control unit 5 deletes portions of the interferogram 370 other than interferograms 371 and 372, as well as duplicate portions between interferograms 371 and 372. Then, the remaining portions of the interferograms 371 and 372 are linked (image linking). Furthermore, in images captured by the image sensor 336, objects appear larger when the shooting distance is close and smaller when the shooting distance is far. Therefore, in addition to correcting the lengths along the direction of the surface 380, the control unit 5 can also correct based on the shooting distance (the distance relative to the surface 380 of the object 308). Therefore, even for objects with curved surfaces (surface 380) such as the object under inspection 308, distortion caused by differences in shooting distance can be corrected, making image linking easier. Furthermore, by correcting the image shooting distance, the visibility of the image of the curved surface 380 of the object under inspection 308 is improved, making it easier for the user to determine the presence or absence of defects (defect 390).

[0150] like Figure 20 As shown, the control unit 5 generates a linked image 373 by performing image correction and image linking on the interference images 370 (interference images 371 and 372).

[0151] Furthermore, the defect inspection device 300 is configured to acquire, based on the interference images 370 (interference images 371 and 372), the displacement 390a of the vibration state caused by the defect 390 of the inspected object 308 (see reference). Figure 20 The defect inspection device 300 can determine whether the object to be inspected 308 has a defect (defect 390) based on the displacement 390a of the acquired vibration state, in the same manner as in the first embodiment.

[0152] Furthermore, the other structures of the third embodiment are the same as those of the first embodiment.

[0153] (Effects of the third implementation mode)

[0154] In the third implementation, the following effect can be obtained.

[0155] Here, the third embodiment is an embodiment designed to solve the following problem: when the object to be inspected has a curved surface, it is difficult to easily expand the measurement area for determining the presence or absence of defects without changing the position of the object to be inspected and the measuring part. That is, in the third embodiment, the defect inspection device 300 and the defect inspection method acquire an interference image 371 representing the vibration state of the object to be inspected 308 as observed from the direction along the first optical path 321 and an interference image 372 representing the vibration state of the object to be inspected 308 as observed from the direction along the second optical path 322. Therefore, interference images (interference image 371 and interference image 372) representing the vibration state can be acquired from two different directions. Therefore, interference images (interference image 371 and interference image 372) representing the vibration state of the inspection object 308 can be acquired from multiple directions relative to the curved surface 380 of the inspection object 308. Thus, unlike the case where an interference image representing the vibration state of the inspection object 308 with the curved surface 380 is acquired from only one direction, the measurement area for determining the presence or absence of defects (defect 390) can be expanded without changing the positions of the inspection object 308 and the measuring unit 3. Consequently, when the inspection object 308 has a curved surface 380, the measurement area for determining the presence or absence of defects (defect 390) can be easily expanded without changing the positions of the inspection object 308 and the measuring unit 3.

[0156] Furthermore, in the defect inspection device 300 based on the third embodiment, the following further effects can be obtained by configuring it as follows.

[0157] Furthermore, in the defect inspection apparatus 300 of the third embodiment, as described above, the measuring unit 3 is configured to simultaneously acquire interference images 370 (interference images 371 and 372) representing the vibration states of mutually different measuring regions of the inspection object 308 having a curved surface 380 by receiving interference light from the laser light passing through the first optical path 321 and the laser light passing through the second optical path 322 in each of regions 330a and 330b. Thus, interference image 371 based on the interference light of the laser light passing through the first optical path 221 and interference image 372 based on the interference light of the laser light passing through the second optical path 322 can be acquired simultaneously, thereby shortening the inspection time for checking whether the inspection object 308 has defects (defects 390).

[0158] Furthermore, in the defect inspection apparatus 300 of the third embodiment, as described above, the control unit 5 is configured to correct the length of at least along the direction along the curved surface 380 of the inspection object 308 of the acquired interference image 370 (interference image 371 and interference image 372) representing the vibration state of the inspection object 308 based on the curvature of the surface 380 of the inspection object 308. This improves the visibility of the image of the curved surface 380 of the inspection object 308, making it easier for the user to determine whether a defect (defect 390) is present.

[0159] Furthermore, in the defect inspection apparatus 300 of the third embodiment, as described above, the control unit 5 is configured to continuously connect interference images 370 (interference images 371 and 372) representing the vibration states of multiple measurement areas in a direction along the curved surface 380 of the object under inspection 308. Thus, the user can centrally view the interference images 371 and 372 representing the vibration states of the object under inspection 308 in multiple measurement areas.

[0160] [Fourth Implementation Form]

[0161] Reference Figures 21-24 The structure of the defect inspection device 400 based on the fourth embodiment will be described. Furthermore, in the figures, structural parts identical to those in the first to third embodiments are labeled with the same symbols.

[0162] The defect inspection device 400 based on the fourth embodiment is configured to acquire an interference image 470 representing the vibration state based on the interference light of laser light reflected from the object under inspection 308 in four directions.

[0163] The measuring unit 3 of the defect inspection device 400 is configured to be based on the measurement unit 3 of the defect inspection device 400. Figure 21 Interference images 470 are acquired by interfering the laser light reflected from the object under inspection 308 and passing through the first optical path 421, the second optical path 422, the third optical path 423, and the fourth optical path 424. The first optical path 421 is the optical path from which light is reflected directly from the object under inspection 308 toward the measuring unit 3. Furthermore, the defect inspection device 400 is configured to guide light to the measuring unit 3 using an optical system such as a mirror or lens, as shown in the third embodiment, corresponding to each of the laser light passing through the second optical path 422, the third optical path 423, and the fourth optical path 424.

[0164] like Figure 22 As shown, the image sensor 436 of the defect inspection device 400 has a light receiving area 430 for receiving light, which includes four areas (area 430a, area 430b, area 430c and area 430d).

[0165] Image sensor 436 receives interference beams from lasers passing through the first optical path 421, the second optical path 422, the third optical path 423, and the fourth optical path 424 in regions 430a, 430b, 430c, and 430d, respectively. Thus, the measurement unit 3 of the defect inspection device 400 can acquire an interference image 470 (see reference) representing the vibration state of the inspection object 308 as observed from all four directions (along the four cardinal directions). Figure 23 ).

[0166] In the light-receiving region 430 of the image sensor 436, the interference image 470 based on the received interference light includes interference image 471, interference image 472, interference image 473, and interference image 474. Interference image 471 is an image of the interference light of the laser light received in region 430a after passing through the first optical path 421. Interference image 472 is an image of the interference light of the laser light received in region 430b after passing through the second optical path 422. Interference image 473 is an image of the interference light of the laser light received in region 430c after passing through the third optical path 423. Interference image 474 is an image of the interference light of the laser light received in region 430d after passing through the fourth optical path 424.

[0167] Similarly to the third embodiment, in the fourth embodiment, such as Figure 24 As shown, the control unit 5 generates a double-page image 475 by performing image correction and image linking on the interference images 470 (interference images 471, 472, 473 and 474).

[0168] Specifically, the control unit 5 corrects the lengths (image corrections) of interferometric images 471, 472, 473, and 474 along the surface 380 of the object under inspection 308 based on the curvature of the surface 380 of the object under inspection 308 in the pre-acquired measurement area. Simultaneously, the control unit 5 removes portions of interferometric images 470 other than those of interferometric images 471, 472, 473, and 474, as well as duplicate portions among them. Then, the remaining portions of interferometric images 471, 472, 473, and 474 are linked (image linking).

[0169] Furthermore, the other structures and effects of the fourth embodiment are the same as those of the third embodiment.

[0170] [Fifth Implementation Form]

[0171] Reference Figures 25-31 The structure of the defect inspection device 500 based on the fifth embodiment will be described. Furthermore, in the figures, structural parts identical to those in the first to fourth embodiments are labeled with the same symbols. Figure 25 This illustrates an example of the convergence and divergence of light related to the imaging of light reflected in the direction along the first optical path 521. Additionally, Figure 26 This illustrates an example of the convergence and divergence of light in relation to the imaging of light reflected in the direction along the second optical path 522.

[0172] In the fifth embodiment, unlike the third embodiment which is configured to simultaneously acquire interference images 371 and 372 representing the vibration states of different measurement regions of the inspection object 308 having a curved surface 380, the fifth embodiment is configured to acquire interference images 571 and 572 representing the vibration states of different measurement regions of the inspection object 308 having a curved surface 380 by switching the interference light of the received laser.

[0173] In the defect inspection apparatus 500, the optical system 504 includes a reflector 541, a reflector 542, and a lens 543. The optical system 504 is configured to guide the laser light reflected from the measurement area, which is different from the measurement area of ​​the inspection object 308 with a curved surface 380, which is reflected towards the measurement unit 3 via the laser light passing through the first optical path 521, toward the measurement unit 3.

[0174] When viewed from a direction orthogonal to the direction in which the object under inspection 308 faces the measuring unit 3, the reflector 541 is configured to overlap with the object under inspection 308. Additionally, as... Figure 25 and Figure 26 As shown, the reflector 542 and the lens 543 are arranged between the measuring unit 3 and the object 8 in a direction facing the measuring unit 3 on the surface 80 of the object 8. Furthermore, a portion of the optical system 504 (lens 543) is arranged on the first optical path 521.

[0175] The defect inspection device 500 based on the fifth embodiment is configured to be able to change the position of the optical system 504 within the housing 40. The defect inspection device 500 is configured such that, by changing the position of the optical system 504, the laser reflected from the surface (curved surface 380) of the object to be inspected 308 and incident on the measuring unit 3 can be switched to a laser passing through the first optical path 521 and a laser passing through the second optical path 522.

[0176] Specifically, the defect inspection device 500 is configured to move (offset) the positions of the reflector 541, reflector 542, and lens 543 in a direction intersecting the direction of the measuring unit 3 and the object to be inspected 8 via an actuator (not shown), thereby switching between states where the laser light passing through the first optical path 521 is incident on the measuring unit 3 (see reference). Figure 25 The optical system 504 (lens 543) is disposed on the first optical path 521, and the laser light from the second optical path 522, which blocks the laser light passing through the first optical path 521 and guides the light through the optical system 504, is incident on the measuring unit 3 (see reference). Figure 26 Furthermore, the position switching of the optical system 504 can be performed by control executed by the control unit 5 or by user operation. Additionally, the defect inspection device 500 can also be configured to switch the laser incident on the measuring unit 3 into a laser passing through the first optical path 221 and a laser passing through the second optical path 222 by simply moving the position of the lens 543.

[0177] In addition, such as Figure 25 and Figure 26 As shown, the measuring unit 3 includes a common image sensor (image sensor 536), which captures interference light of laser light reflected from the object under inspection 308 toward the measuring unit 3 via a first optical path 521 and interference light of laser light reflected from the object under inspection 308 toward a second optical path 522 in a direction different from the first optical path 521.

[0178] In the fifth embodiment, the image sensor (image sensor 536) is configured to capture images transmitted from... Figures 25-27 The interference light of the laser reflected from the first optical path 521 by the object under inspection 308 toward the measuring unit 3, and the interference light of the laser reflected from the object under inspection 8 toward the second optical path 522 in a direction different from the first optical path 521, are photographed.

[0179] like Figure 28 As shown, the image sensor 536 has a light receiving area 530 for receiving the interference light of the laser beam after interference from the measurement unit 3.

[0180] The measurement unit 3 is configured to acquire interference images 571 (see reference) representing the vibration state of the object 308 with curved surface 380 in different measurement areas by switching the interference light of the laser received in the common area (light receiving area 530) of the light receiving area of ​​the image sensor 36 to interference light of the laser reflected from different measurement areas of the object 308 with curved surface 380, passing through the first optical path 521 and the second optical path 522. Figure 29 ) and interferometric image 572 (reference) Figure 30).

[0181] In the fifth implementation form, such as Figure 31 As shown, the control unit 5 generates a double-page image 573 by performing image correction and image linking on the interference images 571 and 572.

[0182] Specifically, the control unit 5 corrects the lengths (image correction) of interferograms 571 and 572 along the surface 380 of the object 308 in the pre-acquired measurement area based on the curvature of the surface 380 of the object 308. Simultaneously, the control unit 5 removes overlapping portions between interferograms 571 and 572. Then, the remaining portions of interferograms 571 and 572 are linked (image linking).

[0183] Furthermore, the other structures of the fifth embodiment are the same as those of the third and fourth embodiments.

[0184] (Effects of the fifth implementation mode)

[0185] In the fifth implementation, the following effect can be obtained.

[0186] In the fifth embodiment, when the object to be inspected 308 has a curved surface 380, the defect inspection device 500 and the defect inspection method can easily expand the measurement area for determining whether there is a defect (defect 390) without changing the position of the object to be inspected 308 and the measuring part 3.

[0187] Furthermore, in the defect inspection device 500 based on the fifth embodiment, the following further effects can be obtained by configuring it as follows.

[0188] Furthermore, in the fifth embodiment of the defect inspection apparatus 500, as described above, the measuring unit 3 is configured to acquire interference images 571 and 572 representing the vibration state of the inspection object 308 with a curved surface 380 in different measuring areas by switching the interference light of the laser received in the common area (light receiving area 530) of the light receiving area of ​​the image sensor 536 (imaging unit) to interference light of the laser passing through the first optical path 521 and interference light of the laser passing through the second optical path 522. Thus, by switching the interference light of the laser received in the common area (light receiving area 530) of the light receiving area of ​​the image sensor 536, the measuring unit 3 acquires interference images 571 and 572, respectively. Therefore, it is possible to acquire interference light of the laser passing through the first optical path 521 and interference light of the laser passing through the second optical path 522 without dividing the light receiving area 530 of the image sensor 536 into multiple areas. As a result, compared to the case where the light receiving area 530 of the image sensor 536 is divided into multiple areas and the interference light of the laser passing through the first optical path 521 and the interference light of the laser passing through the second optical path 522 are received simultaneously, the interference light of the laser passing through the first optical path 521 and the interference light of the laser passing through the second optical path 522 can be acquired over a wider area. Therefore, the interference images 571 and 572 can be acquired over a wider measurement area.

[0189] Furthermore, the other effects of the fifth embodiment are the same as those of the third embodiment.

[0190] [Variation Example]

[0191] Furthermore, the embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of the invention is defined by the claims rather than by the description of the embodiments described above, and includes all modifications (variations) within the meaning and scope equivalent to the claims.

[0192] For example, in the first to fifth embodiments, examples are shown where the laser illumination 2 (irradiation section) is disposed between the surface 80 of the object under inspection 8 and the measuring section 3, or between the curved surface 380 of the object under inspection 308 and the measuring section 3; however, the present invention is not limited thereto. In the present invention, the measuring section and the irradiation section may also be disposed at approximately the same position in the direction facing the surface of the object under inspection. In this case, the measuring section and the irradiation section are disposed adjacent to each other in the direction along the surface of the object under inspection. That is, the measuring section and the irradiation section are disposed offset in the direction along the surface of the object under inspection.

[0193] Furthermore, in the first embodiment, an example is shown that includes an optical system 4, which guides the laser light passing through the second optical path 22 toward a measuring unit 3 that measures the interference light of the laser light passing through the first optical path 21. However, the present invention is not limited to this. In the present invention, the optical system may be omitted, and measuring units may be provided corresponding to the laser light passing through the first optical path and the laser light passing through the second optical path.

[0194] Furthermore, in the aforementioned embodiment, an example is shown where the interference light of the laser passing through the first optical path 21 and the interference light of the laser passing through the second optical path 22 are received by the image sensor 36 (capturing unit), but the present invention is not limited thereto. In the present invention, the capturing unit may also be provided corresponding to the interference light of the laser passing through the first optical path and the laser passing through the second optical path.

[0195] Furthermore, in the first to fifth embodiments, examples were shown in which laser light was incident on the measuring unit 3 via the first optical path 21, first optical path 221, first optical path 321, or first optical path 521 without passing through an optical system; however, the present invention is not limited thereto. In the present invention, the laser light passing through the first optical path may also be incident on the measuring unit via an optical system such as a mirror or lens.

[0196] Furthermore, in the first embodiment, an example is shown of obtaining a composite image 73 obtained by combining the first interference image 71 and the second interference image 72. In the second embodiment, an example is shown of obtaining a composite image 273 obtained by combining the first interference image 271 and the second interference image 272. However, the present invention is not limited thereto. In the present invention, it is also possible to obtain only the first interference image and the second interference image without obtaining the composite image.

[0197] Furthermore, in the third to fifth embodiments, examples are shown where the control unit 5 (image processing unit) performs image correction processing and image linking processing on the interferometric images (interferometric images 371, 372, 471, 472, 473, 474, 571, and 572), but the present invention is not limited thereto. In the present invention, the image processing unit may also be configured to perform only image correction processing or image linking processing on the interferometric images, or it may not perform either image correction processing or image linking processing.

[0198] Furthermore, in the third to fifth embodiments described above, an example is shown where the laser light irradiated from the laser illumination 2 (irradiation unit) is reflected by the reflector 320, but the present invention is not limited thereto. In the present invention, it is also possible to... Figure 32As shown in the first modified example of the defect inspection device 600, it is configured to provide multiple laser illuminations 2 to irradiate the inspection object 308 with the curved surface 380 from multiple directions.

[0199] Furthermore, in the first and second embodiments, examples are shown where the object to be inspected 8 is a plate-shaped member, and in the third to fifth embodiments, examples are shown where the object to be inspected 308 is an object having a cylindrical or cylindrical shape; however, the present invention is not limited thereto. In the present invention, the object to be inspected may be an object with a shape composed of a combination of curved and flat surfaces, or it may be an object with a bowl-shaped shape.

[0200] [form]

[0201] Those skilled in the art will understand that the exemplary embodiments described above are specific examples of the following forms.

[0202] (Project 1)

[0203] A defect inspection device, comprising:

[0204] The excitation section imparts elastic wave vibration to the object under inspection and excites it.

[0205] An irradiation unit irradiates the object under inspection with a laser while it is in a state of elastic wave vibration excited by the excitation unit; and

[0206] The measuring unit causes a phase change in the laser light reflected by the object under inspection, causes the laser light before and after the phase change to interfere with each other, and measures the interference light.

[0207] The measuring unit is configured to acquire an interference image representing the vibration state of the object under inspection as observed from the direction along the first optical path, based on interference light of the laser beam irradiated from the irradiation unit and reflected from the object under inspection toward the measuring unit via a first optical path; and to acquire an interference image representing the vibration state of the object under inspection as observed from the direction along the second optical path, based on interference light of the laser beam irradiated from the irradiation unit and reflected from the object under inspection toward a second optical path different from the first optical path.

[0208] (Project 2)

[0209] The defect inspection device according to Project 1 further includes: an optical system that guides the laser light, which has passed through a second optical path reflected in a direction different from the first optical path, toward the measuring unit.

[0210] The measuring unit is configured to acquire an interference image representing the vibration state of the object under inspection as observed from the direction along the first optical path, based on interference light of the laser beam reflected directly from the object under inspection toward the measuring unit without passing through the optical system; and to acquire an interference image representing the vibration state of the object under inspection as observed from the direction along the second optical path, based on interference light of the laser beam reflected directly from the second optical path guided by the optical system toward the measuring unit.

[0211] (Project 3)

[0212] According to the defect inspection apparatus of Project 2, the measuring unit includes a common imaging unit that captures interference light of the laser reflected from the object under inspection toward the measuring unit via a first optical path, and interference light of the laser reflected from the object under inspection toward a second optical path that is guided by the optical system toward the measuring unit via a second optical path that is reflected by the object under inspection toward a direction different from the first optical path.

[0213] (Project 4)

[0214] According to any one of items 1 to 3, the defect inspection apparatus wherein the measuring unit is configured to acquire an interference image representing the vibration state of the inspection object as observed from the front direction based on interference light of the laser light passing through a first optical path orthogonal to the surface of the inspection object facing the measuring unit, and to acquire an interference image representing the vibration state of the inspection object as observed from the tilted direction based on interference light of the laser light passing through a second optical path orthogonal to the surface of the inspection object facing the front direction.

[0215] (Project 5)

[0216] According to the defect inspection apparatus of Project 3, the measuring unit is configured to acquire a first interference image representing the vibration state observed from the front direction based on interference light of the laser reflected from the inspection object in a first optical path that is not via the optical system but faces the measuring unit in a direction orthogonal to the surface of the inspection object; and to acquire a second interference image representing the vibration state observed from the tilted direction based on interference light of the laser reflected in a second optical path that is different from the first optical path but in an inclined direction relative to the surface of the inspection object that is reflected by the laser in a common direction to the surface of the inspection object facing the measuring unit, and guided by the optical system towards the measuring unit.

[0217] (Project 6)

[0218] According to the defect inspection device described in Project 5, the imaging unit has a light receiving area for receiving the interference light of the laser beam after interference from the measuring unit.

[0219] The optical system is located outside the first optical path and is configured to guide the laser light passing through the second optical path toward the measuring unit.

[0220] The measuring unit is configured to receive, in each of the multiple regions of the light receiving region corresponding to the interference light of the laser passing through the first optical path and the interference light of the laser passing through the second optical path, the interference light reflected from the common surface of the object under inspection, and simultaneously acquire the first interference image and the second interference image.

[0221] (Project 7)

[0222] According to the defect inspection device described in Project 5, the imaging unit has a light receiving area for receiving the interference light of the laser beam after interference from the measuring unit.

[0223] The measuring unit is configured to acquire the first interference image and the second interference image by switching the interference light of the laser received in the common area of ​​the light receiving area of ​​the imaging unit to the interference light of the laser reflected from the common surface of the object under inspection, passing through the first optical path and the interference light of the laser passing through the second optical path.

[0224] (Project 8)

[0225] The defect inspection apparatus according to any one of items 5 to 7 further includes: an image processing unit configured to acquire a composite image obtained by combining the first interference image and the second interference image, wherein the first interference image represents a vibration state observed from the front direction of the measuring unit along a direction orthogonal to the surface of the object being inspected, and the second interference image represents a vibration state observed from an inclined direction relative to the surface of the object being inspected in the measuring area of ​​the object being inspected.

[0226] (Project 9)

[0227] According to the defect inspection apparatus of Project 8, the image processing unit is configured to correct the distortion of at least the second interference image in the first interference image and the second interference image, wherein the first interference image represents a vibration state observed from the front direction of the measuring unit along a direction orthogonal to the surface of the object being inspected, and the second interference image represents a vibration state observed from the tilt direction relative to the surface of the object being inspected in the measuring area of ​​the object being inspected.

[0228] (Project 10)

[0229] According to the defect inspection device described in Project 3, the object to be inspected is an object with a curved surface.

[0230] The imaging unit has a light receiving area for receiving the interference light of the laser beam after interference from the measuring unit.

[0231] The optical system is located outside the first optical path and is configured to guide the laser light reflected from a measurement area (different from the measurement area of ​​the object under inspection with the curved surface) that has passed through the second optical path and is directed toward the measurement unit.

[0232] The measuring unit is configured to simultaneously acquire an interference image representing the vibration state of the different measuring regions of the object under inspection, by receiving interference beams of the laser light reflected from different measuring regions of the object under inspection in each of the multiple regions of the light receiving region of the imaging unit, which are divided into multiple regions corresponding to the interference beams of the laser light passing through the first optical path and the laser light passing through the second optical path.

[0233] (Project 11)

[0234] According to the defect inspection device described in Project 3, the object to be inspected is an object with a curved surface.

[0235] The imaging unit has a light receiving area for receiving the interference light of the laser beam after interference from the measuring unit.

[0236] The optical system is configured to guide the laser light reflected from a measurement area (different from the measurement area of ​​the object under inspection with the curved surface) that is reflected from the laser light passing through the first optical path toward the measurement unit, via the second optical path, toward the measurement unit.

[0237] The measuring unit is configured to acquire interference images representing the vibration state of the object under inspection with the curved surface in different measuring areas by switching the interference light of the laser received in the common area of ​​the light receiving area of ​​the imaging unit to interference light of the laser reflected from different measuring areas of the object under inspection with the curved surface that passes through the first optical path and interference light of the laser that passes through the second optical path.

[0238] (Project 12)

[0239] The defect inspection apparatus according to item 10 or 11 further includes: an image processing unit configured to correct, based on the curvature of the surface of the object under inspection, the length of at least in the direction along the surface of the object under inspection of the acquired interference image representing the vibration state of the object under inspection.

[0240] (Project 13)

[0241] According to the defect inspection apparatus of Project 12, the measuring unit is configured to acquire interference images representing the vibration state in multiple measuring regions of the object under inspection.

[0242] The image processing unit is configured to continuously link interferometric images representing the vibration states of multiple measurement areas along the direction of the surface of the object under inspection.

[0243] (Project 14)

[0244] A defect inspection method, wherein the object to be inspected is subjected to elastic wave vibration and excited.

[0245] The object under inspection, which is in a state of excited elastic wave vibration, is irradiated with a laser.

[0246] Based on the interference light of the laser reflected by the measuring unit (which causes a phase change in the laser reflected by the object under inspection, causes the laser before and after the phase change to interfere with each other, and measures the interference light), an interference image representing the vibration state of the object under inspection as observed from the direction along the first optical path is obtained. Furthermore, based on the interference light of the laser reflected from the object under inspection in a second optical path different from the first optical path, an interference image representing the vibration state of the object under inspection as observed from the direction along the second optical path is obtained.

[0247] [Explanation of Symbols]

[0248] 1: Vibrator (excitation unit)

[0249] 2: Laser illumination (irradiation area)

[0250] 3: Measurement Section

[0251] 4, 204, 304, 504: Optical systems

[0252] 5: Control Unit (Image Processing Unit)

[0253] 8. 308: Inspection object

[0254] 21, 221, 321, 421, 521: First optical path

[0255] 22, 222, 322, 422, 522: Second optical path

[0256] 30, 230, 330, 430, 530: Light receiving area

[0257] 30a, 30b, 330a, 330b, 430a, 430b, 430c, 430d: Areas

[0258] 36, 236, 336, 436, 536: Image sensor (imaging unit)

[0259] 70°, 37°, 47°: Interference images

[0260] 71, 271: First interferometric image

[0261] 72, 272: Second interferometric images

[0262] 73, 273: Composite images

[0263] 80: (The surface of the object being inspected)

[0264] 100, 200, 300, 400, 500, 600: Defect inspection device

[0265] 380: (The surface of the object being inspected)

[0266] 371, 372, 471, 472, 473, 474, 571, 572: Interference images.

Claims

1. A defect inspection device, characterized in that, include: The excitation section imparts elastic wave vibration to the object under inspection and excites it. An irradiation unit irradiates the object under inspection with a laser while it is in a state of elastic wave vibration excited by the excitation unit; and The measuring unit causes a phase change in the laser light reflected by the object under inspection, causes the laser light before and after the phase change to interfere with each other, and measures the interference light. The measuring unit is configured to acquire an interference image representing the vibration state of the object under inspection as observed from the direction along the first optical path, based on interference light of the laser beam irradiated from the irradiation unit and reflected from the object under inspection toward the measuring unit via a first optical path; and to acquire an interference image representing the vibration state of the object under inspection as observed from the direction along the second optical path, based on interference light of the laser beam irradiated from the irradiation unit and reflected from the object under inspection toward a second optical path different from the first optical path.

2. The defect inspection device according to claim 1, wherein, Also includes: The optical system guides the laser light, which has passed through the second optical path and reflected in a direction different from the first optical path, toward the measuring unit. The measuring unit is configured to acquire an interference image representing the vibration state of the object under inspection as observed from the direction along the first optical path, based on interference light of the laser beam reflected directly from the object under inspection toward the measuring unit without passing through the optical system; and to acquire an interference image representing the vibration state of the object under inspection as observed from the direction along the second optical path, based on interference light of the laser beam reflected directly from the second optical path guided by the optical system toward the measuring unit.

3. The defect inspection device according to claim 2, wherein, The measuring unit includes a common imaging unit that captures interference light of the laser beam reflected from the object under inspection toward the measuring unit via a first optical path, and interference light of the laser beam reflected from the object under inspection toward a second optical path that is guided by the optical system toward the measuring unit via a second optical path that is reflected from the object under inspection toward a direction different from the first optical path.

4. The defect inspection device according to claim 1, wherein, The measuring unit is configured to acquire an interference image representing the vibration state of the object under inspection as observed from the front direction, based on interference light of the laser beam reflected from the object under inspection in a first optical path orthogonal to the surface of the object under inspection facing the measuring unit, and to acquire an interference image representing the vibration state of the object under inspection as observed from the tilted direction, based on interference light of the laser beam reflected in a second optical path orthogonal to the surface of the object under inspection facing the front direction.

5. The defect inspection device according to claim 3, wherein, The measuring unit is configured to acquire a first interference image representing the vibration state observed from the front direction based on interference light of the laser reflected from the object under inspection in a first optical path that is not via the optical system but is directed toward the measuring unit in a direction orthogonal to the surface of the object under inspection; and to acquire a second interference image representing the vibration state observed from the tilted direction based on interference light of the laser reflected in a second optical path that is different from the first optical path but in an oblique direction relative to the surface of the object under inspection that is reflected in the first optical path that is directed toward the measuring unit by the optical system.

6. The defect inspection device according to claim 5, wherein, The imaging unit has a light receiving area for receiving the interference light of the laser beam after interference from the measuring unit. The optical system is located outside the first optical path and is configured to guide the laser light passing through the second optical path toward the measuring unit. The measuring unit is configured to receive, in each of the multiple regions of the light receiving region corresponding to the interference light of the laser passing through the first optical path and the interference light of the laser passing through the second optical path, the interference light reflected from the common surface of the object under inspection, and simultaneously acquire the first interference image and the second interference image.

7. The defect inspection device according to claim 5, wherein, The imaging unit has a light receiving area for receiving the interference light of the laser beam after interference from the measuring unit. The measuring unit is configured to acquire the first interference image and the second interference image by switching the interference light of the laser received in the common area of ​​the light receiving area of ​​the imaging unit to the interference light of the laser reflected from the common surface of the object under inspection, passing through the first optical path and the interference light of the laser passing through the second optical path.

8. The defect inspection device according to claim 5, wherein, Also includes: The image processing unit is configured to acquire a composite image obtained by combining the first interference image and the second interference image. The first interference image represents the vibration state observed from the front direction of the measuring unit along a direction orthogonal to the surface of the object being inspected, and the second interference image represents the vibration state observed from an inclined direction relative to the surface of the object being inspected in the measuring area of ​​the object being inspected.

9. The defect inspection device according to claim 8, wherein, The image processing unit is configured to correct distortions in at least one of the first interference image and the second interference image, wherein the first interference image represents a vibration state observed from the front direction of the measuring unit along a direction orthogonal to the surface of the object being inspected, and the second interference image represents a vibration state observed from the tilt direction relative to the surface of the object being inspected in the measuring area of ​​the object being inspected.

10. The defect inspection device according to claim 3, wherein, The object being inspected is an object with a curved surface. The imaging unit has a light receiving area for receiving the interference light of the laser beam after interference from the measuring unit. The optical system is located outside the first optical path and is configured to guide the laser light reflected from a measurement area (different from the measurement area of ​​the object under inspection with the curved surface) that has passed through the second optical path and is directed toward the measurement unit. The measuring unit is configured to simultaneously acquire an interference image representing the vibration state of the different measuring regions of the object under inspection, by receiving interference beams of the laser light reflected from different measuring regions of the object under inspection in each of the multiple regions of the light receiving region of the imaging unit, which are divided into multiple regions corresponding to the interference beams of the laser light passing through the first optical path and the laser light passing through the second optical path.

11. The defect inspection device according to claim 3, wherein, The object being inspected is an object with a curved surface. The imaging unit has a light receiving area for receiving the interference light of the laser beam after interference from the measuring unit. The optical system is configured to guide the laser light reflected from a measurement area (different from the measurement area of ​​the object under inspection with the curved surface) that is reflected from the laser light passing through the first optical path toward the measurement unit, via the second optical path, toward the measurement unit. The measuring unit is configured to acquire interference images representing the vibration state of the object under inspection with the curved surface in different measuring areas by switching the interference light of the laser received in the common area of ​​the light receiving area of ​​the imaging unit to interference light of the laser reflected from different measuring areas of the object under inspection with the curved surface that passes through the first optical path and interference light of the laser that passes through the second optical path.

12. The defect inspection apparatus according to claim 10, wherein, Also includes: The image processing unit is configured to correct the length of at least one direction along the surface of the object under inspection of the acquired interference image representing the vibration state of the object under inspection, based on the curvature of the surface of the object under inspection.

13. The defect inspection apparatus according to claim 12, wherein, The measuring unit is configured to acquire interference images representing the vibration state in multiple measuring regions of the object under inspection. The image processing unit is configured to continuously link interferometric images representing the vibration states of multiple measurement areas along the direction of the surface of the object under inspection.

14. A defect inspection method, characterized in that, The object under inspection is subjected to elastic wave vibration and excited. The object under inspection, which is in a state of excited elastic wave vibration, is irradiated with a laser. Based on the interference light of the laser reflected by the measuring unit through a first optical path that is directed toward the measuring unit such that the phase of the laser reflected by the object under inspection changes, the lasers before and after the phase change interfere with each other, and the interference light is measured, an interference image representing the vibration state of the object under inspection as observed from the direction along the first optical path is obtained. Furthermore, based on the interference light of the laser reflected from the object under inspection in a second optical path that is directed toward a direction different from the first optical path, an interference image representing the vibration state of the object under inspection as observed from the direction along the second optical path is obtained.

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