Inspecting device and inspecting method

Abstract

According to the present invention, an optical probe generates images of an inspection target surface of an object. A storage unit stores relationship information indicating a relationship between feature quantities of a plurality of light-section images obtained by imaging the inspection target surface of a sample under a plurality of exposure conditions and adjustment information for adjusting the exposure conditions such that the feature quantities of each of the plurality of light-section images of the sample approach a target value. A control unit controls the optical probe. The control unit operates the optical probe under a first exposure condition to acquire an image of the inspection target surface of the object. A second exposure condition is determined on the basis of the feature quantity of the light-section image within the acquired image, the relationship information stored in the storage unit, and the first exposure condition. In addition, the optical probe is operated to acquire an image of the inspection target surface of the object under the second exposure condition.

Description

Inspection device and inspection method

[0001] The present invention relates to an inspection device and an inspection method.

[0002] An apparatus for inspecting the inner surface of a tubular body is known (see Patent Document 1). This inspection apparatus irradiates the inner surface of the tubular body with an annular beam to capture an image of the inner surface. Information such as the inner diameter is obtained by analyzing a light-section image in the captured image. Analysis of the light-section image includes, for example, detecting the peak position of the brightness distribution in the thickness direction of the light-section image.

[0003] Japanese Patent Application Laid-Open No. 2019-60722

[0004] To accurately detect the peak position of the brightness distribution, the exposure (shutter speed, aperture, gain) when acquiring the image must be appropriately adjusted. For example, if the exposure is too low, the brightness of the light-section image will be close to the noise level, making the peak position more susceptible to noise. If the exposure is too high, the brightness near the peak position of the light-section image will exceed the saturation value, making it impossible to accurately detect the peak position.

[0005] Furthermore, because the surface of an object is affected by variations in various manufacturing conditions (e.g., processing conditions, heat treatment conditions), the brightness recorded in the image also varies for each object. According to the inventor's evaluation, variations in processing conditions, heat treatment conditions, etc. can result in a difference of approximately 1,000 times in the appropriate shutter speed between objects. Determining the appropriate exposure conditions requires repeated trial and error. An object of the present invention is to provide an inspection device and an inspection method that can determine the appropriate exposure conditions without repeated trial and error.

[0006] According to one aspect of the present invention, there is provided an inspection device comprising: an optical probe that generates an image of an inspected surface of an object; a memory unit that stores relationship information indicating the relationship between feature amounts of a plurality of light section images obtained by imaging the inspected surface of the sample under a plurality of exposure conditions and adjustment information for adjusting the exposure conditions so that each feature amount of the plurality of light section images of the sample approaches a target value; and a control unit that controls the optical probe, wherein the control unit operates the optical probe under a first exposure condition to obtain an image of the inspected surface of the object, determines a second exposure condition based on the feature amounts of the light section images in the obtained image, the relationship information stored in the memory unit, and the first exposure condition, and operates the optical probe under the second exposure condition to obtain an image of the inspected surface of the object.

[0007] According to another aspect of the present invention, there is provided an inspection method including: acquiring an image of an inspected surface of an object under a first exposure condition; determining a second exposure condition from relationship information indicating the relationship between feature amounts of a plurality of light-section images obtained by imaging the inspected surface of the sample under a plurality of exposure conditions and adjustment information for adjusting the exposure conditions so that each feature amount of the plurality of light-section images of the sample approaches a target value; the feature amounts of the light-section images in the acquired image; and the first exposure condition; and acquiring an image of the inspected surface of the object under the second exposure condition.

[0008] According to yet another aspect of the present invention, there is provided an inspection device comprising: an optical probe that generates an image of an inspected surface of an object; a memory unit that stores relationship information indicating a relationship between feature amounts of a light section image obtained from a sample and adjustment information for adjusting exposure conditions at that time to more suitable exposure conditions; and a control unit having a function of controlling the optical probe and a function of acquiring a lot ID of an object to be inspected next, wherein the control unit, if an object having the same lot ID as the object to be inspected next has not yet been inspected, operates the optical probe under first exposure conditions to acquire an image of the inspected surface of the object, determines second exposure conditions based on the feature amounts of the light section image in the acquired image, the relationship information stored in the memory unit, and the first exposure conditions, operates the optical probe under the second exposure conditions to acquire an image of the inspected surface of the object, and if an object having the same lot ID as the object to be inspected next has already been inspected, acquires an image of the inspected surface of the object under exposure conditions that are the same as the second exposure conditions that were applied when the object having the same lot ID was inspected.

[0009] By acquiring an image of the inspection surface of the object under the first exposure conditions, it is possible to determine the appropriate second exposure conditions without repeated trial and error.

[0010] FIG. 1 is a schematic diagram of an inspection device according to a first embodiment. FIG. 2 is a schematic perspective view of an optical probe 10. FIGS. 3A and 3C are diagrams showing an example of a light-section image 30, and FIGS. 3B and 3D are graphs showing a luminance distribution 31 in the radial direction of the light-section images shown in FIGS. 3A and 3C, respectively. FIG. 4A is a graph showing an example of the relationship between the shutter speed and the number of pixels Ngt evaluated for a sample, and FIG. 4B is a graph showing the relationship between the number of pixels Ngt and the shutter speed adjustment coefficient (S ＳＴ / S Ｓ１ ) is a graph showing the relationship between the time (t) and the time (f). FIG. 5 is a flowchart showing the procedure of the inspection method according to the first embodiment. FIG. 6 is a schematic diagram of the inspection device according to the second embodiment. FIG. 7 is a schematic diagram of the inspection device according to the second embodiment. FIG. 8 is a flowchart showing the procedure of inspection performed by the inspection device according to the third embodiment.

[0011] 1 to 5, an inspection apparatus and an inspection method according to a first embodiment will be described. Fig. 1 is a schematic diagram of the inspection apparatus according to the first embodiment. The inspection apparatus according to the first embodiment inspects the inner peripheral surface of an object 60 to be inspected by irradiating the inner peripheral surface with an annular beam.

[0012] A workpiece placement section 52 is provided on a support plate 51 arranged in the internal space of the housing 50. A tubular object 60, for example, to be inspected, is held on the workpiece placement section 52. The object 60 is fixed in a position in which its central axis is parallel to the vertical direction. The optical probe 10 is supported by a support mechanism 18 so as to be movable along the central axis of the object 60. During inspection, the optical probe 10 descends and enters the space inside the object 60 along its central axis. When the inspection is completed, the optical probe 10 ascends and exits the space inside the object 60.

[0013] The optical probe 10 includes an optical module 11, an imaging device 12, and an optical module fixing member 13. The position of the optical module 11 relative to the imaging device 12 is fixed by the optical module fixing member 13.

[0014] The housing 50 houses the laser light source 15 and a control box 42. The laser light source 15 is, for example, a laser diode that outputs a laser beam with a wavelength in the range of 370 nm to 1100 nm. Laser light is introduced from the laser light source 15 to the optical module 11 via an optical fiber 16. The control box 42 controls the laser light source 15 and the support mechanism 18 in response to commands from a higher-level control unit 40. An image captured by the imaging device 12 is input to the control unit 40, where image analysis is performed. Information stored in the memory unit 41 is used during the image analysis. The inner diameter of the object 60 can be measured based on the results of the image analysis.

[0015] The housing 50 can be moved on the floor by means of wheels 53 .

[0016] Next, the positional relationship between the optical module 11, the object 60, and the imaging device 12, and the function of the optical probe 10 will be described with reference to FIG.

[0017] 2 is a schematic perspective view of the optical probe 10. The optical probe 10 includes an optical module 11 and an imaging device 12. The optical module 11 includes a collimating lens 11A and a mirror 11B. The position of the mirror 11B is fixed relative to the collimating lens 11A by, for example, a transparent member (not shown) or a plurality of supports.

[0018] Laser light is guided from the laser light source 15 to the optical module 11 via the optical fiber 16. The laser light output from the output end of the optical fiber 16 is collimated by the collimating lens 11A.

[0019] Mirror 11B is disposed at the position where the collimated light is incident. Mirror 11B has a conical reflecting surface. The rotation axis of this conical surface coincides with the optical axis of the collimated light (the optical axis of collimating lens 11A). Mirror 11B reflects the collimated light to generate annular beam 20 that spreads in the circumferential direction of the inner circumferential surface of object 60.

[0020] When the apex angle of the conical reflecting surface of mirror 11B is 90°, the annular beam 20 spreads into a disk (sheet). The inner surface of object 60 is a rough surface with irregularities equal to or larger than the wavelength of the annular beam 20. When the annular beam 20 is incident on the inner surface of object 60, diffuse reflection occurs. The location where diffuse reflection occurs is referred to as the diffuse reflection location 21. The diffuse reflection location 21 is along the intersection between a plane perpendicular to the central axis of object 60 and the inner surface of object 60. If the inner surface is a cylindrical surface, the diffuse reflection location 21 will have a circumferential shape. A portion of the reflected light 22 diffusely reflected at the diffuse reflection location 21 enters the imaging device 12. The imaging device 12 receives the reflected light 22 and generates image data (sometimes simply referred to as an "image"). That is, the optical probe 10 generates an image of the inner surface (surface to be inspected) of object 60.

[0021] The generated image is input to the control unit 40 (FIG. 1). The control unit 40 performs image analysis to obtain information about the inner surface of the object 60, such as the inner diameter, the shape of the cut surface, and the presence or absence of scratches on the surface. Information for determining the exposure conditions (shutter speed, aperture, gain) of the imaging device 12 is stored in the storage unit 41 (FIG. 1).

[0022] Next, the functions of the control unit 40 will be described. The control unit 40 has a function of operating the optical probe 10 under a first exposure condition and acquiring an image of the test surface of the object 60 from the optical probe 10. The storage unit 41 stores relationship information indicating the relationship between feature quantities of multiple light-section images obtained by imaging the test surface of the sample under multiple exposure conditions and adjustment information for adjusting the exposure conditions so that each feature quantity of the multiple light-section images of the sample approaches a target value. The relationship information stored in the storage unit 41 will be described later with reference to FIGS. 4A and 4B. The control unit 40 also has a function of determining appropriate second exposure conditions from the feature quantities of the light-section images in the acquired image, the relationship information stored in the storage unit 41, and the first exposure conditions. A method for determining the second exposure conditions will be described later with reference to FIGS. 4A and 4B. The control unit 40 also has a function of operating the optical probe 10 under the second exposure condition and acquiring an image of the test surface of the object 60.

[0023] Next, the light-section image and luminance distribution will be described with reference to Figures 3A to 3D. Figures 3A and 3C are diagrams showing an example of a light-section image 30. When the inner circumferential surface of the object 60 is a cylindrical surface, the light-section image 30 will be circumferential. Figures 3B and 3D are graphs showing the radial luminance distribution 31 of the light-section images shown in Figures 3A and 3C, respectively. Figure 3C is a light-section image acquired with a slower shutter speed than that of Figure 3A. Here, "shutter speed" refers to the time the shutter of the imaging device 12 is open, and "slow shutter speed" refers to a long time the shutter is open.

[0024] By detecting the position in the radial direction r where the peak of the luminance distribution 31 appears, the inner peripheral surface of the object 60 is inspected, for example, the inner diameter is measured. To improve the inspection accuracy, it is necessary to detect the position of the peak of the luminance distribution 31 with high accuracy. To detect the peak position of the luminance distribution 31 with high accuracy, for example, subpixel processing is used. When measuring the average inner diameter, a fitting method may be used to find the circumference that best fits a closed curve that connects the peak positions of the luminance distribution 31.

[0025] If the shutter speed is too fast, the peak value of the luminance distribution will be low, as shown in FIG. 3B, and the detected peak position will be more susceptible to noise. If the shutter speed is too slow, the peak value of the luminance distribution 31 will exceed the saturation level Bsat, as shown in FIG. 3D. If the peak value exceeds the saturation level Bsat, it will be difficult to accurately detect the peak position. In particular, if the luminance distribution 31 is asymmetric, the deviation in the estimated peak position will be large. In the first embodiment, it is possible to determine a preferred shutter speed for detecting the peak position with high accuracy using a simple method.

[0026] Next, with reference to FIGS. 4A and 4B , the “relationship information indicating the relationship between the feature quantities of the light-section image obtained from the sample and the adjustment information for adjusting the exposure conditions at that time to suitable exposure conditions” stored in the memory unit 41 will be described.

[0027] For a sample manufactured under the same manufacturing conditions as the object 60, images of the surface to be inspected are acquired at various shutter speeds, and the number of pixels Ngt is counted for the light-section image within the image. FIG. 4A is a graph showing an example of the relationship between the shutter speed and the number of pixels Ngt evaluated for the sample. The horizontal axis represents the shutter speed on a logarithmic scale, and the vertical axis represents the number of pixels Ngt on a logarithmic scale. The relationship between the shutter speed and the number of pixels Ngt obtained for the sample (hereinafter referred to as the exposure condition-number of pixels relationship) is represented by the thick solid line Ns. The thin solid line Nx in the graph indicates the relationship between the exposure condition and the number of pixels for the object 60. However, the relationship between the exposure condition and the number of pixels for the object 60 is unknown.

[0028] As the shutter speed increases, the brightness of the light-section image increases, and the number of pixels Ngt increases. Even for products manufactured under the same manufacturing conditions, variations in the reflectance and scattering angle of the inner circumferential surface (surface to be inspected) occur due to manufacturing variations. As a result, the amount of light incident on the imaging device 12 changes. For this reason, the curve representing the relationship between exposure conditions and number of pixels differs for each product. Therefore, the relationship between exposure conditions and number of pixels obtained for the sample (solid line Ns) and the relationship between exposure conditions and number of pixels obtained for the object 60 (solid line Nx) are not necessarily the same.

[0029] The inventors of the present application focused on the feature quantity of a light-section image as an index for determining a preferred shutter speed. The shutter speed is adjusted so that the feature quantity of a light-section image acquired at a certain shutter speed approaches a target value, thereby determining a preferred shutter speed that can improve inspection accuracy. In a first embodiment, the feature quantity of the light-section image is the number of pixels (hereinafter referred to as the pixel number Ngt) that have a brightness exceeding a predetermined threshold value among the pixels constituting the light-section image.

[0030] First, for one sample, the number of pixels Ngt was determined when a luminance distribution 31 (FIGS. 3B and 3D) was obtained, which allowed the peak position of the luminance distribution to be detected with high accuracy. Similar evaluation experiments were performed on other samples, and it was found that this number of pixels Ngt was almost the same for all samples. The number of pixels Ngt when a luminance distribution 31 was obtained, which allowed the peak position of the luminance distribution to be detected with high accuracy, was set as the target value N Ｔ Let's assume that this is the case.

[0031] As shown in FIG. 4A, for one sample, the number of pixels Ngt is set to the target value N Ｔ The shutter speed at which ＳＴ The shutter speed is S. Ｓ１ The number of pixels Ngt when set to N １ It is marked as follows.

[0032] For the object 60, the number of pixels Ngt is the target value N Ｔ The shutter speed at which Ｔ The number of pixels Ngt is N １ The shutter speed at which １ Assuming that the reflectance and scattering angle of the inner circumferential surface (surface to be inspected) of each of the plurality of objects 60 are different and therefore the amount of light incident on the image capturing device 12 is different, and the brightness of the light-section image changes depending on the amount of light, the relationship between the exposure condition and the number of pixels for the object 60 (solid line Nx) can be considered to be the relationship between the exposure condition and the number of pixels for the sample (solid line Ns) stretched or contracted in the horizontal direction. Various evaluation experiments conducted by the inventors have confirmed that this assumption is met.

[0033] Assuming that the solid line Nx is obtained by expanding or contracting the solid line Ns in the horizontal direction, the following equation is established: Ｓ１ / S １ = S ＳＴ / S Ｔ ...(1) By transforming equation (1), the following equation is obtained: S Ｔ = S １ × (S ＳＴ / S Ｓ１ ) ... (2) Shutter speed S ＳＴ is a predetermined fixed value, but the shutter speed S Ｓ１ is the number of pixels N １ Therefore, (S ＳＴ / S Ｓ１ ) is the number of pixels N １ This function is a function of the exposure condition-pixel number relationship (solid line N Ｓ ) can be predetermined.

[0034] For the object 60, the shutter speed S １ The number of pixels of the light section image obtained is N １ Once this is known, (S ＳＴ / S Ｓ１ ) can be determined. １ To (S ＳＴ / S Ｓ１ ) to obtain the target shutter speed S Ｔ is calculated. １ Coefficient to be multiplied by (S ＳＴ / S Ｓ１ ) is referred to as the shutter speed adjustment coefficient.

[0035] FIG. 4B shows the relationship between the number of pixels Ngt and the shutter speed adjustment coefficient (S ＳＴ / S Ｓ１ ) is a graph showing an example of the relationship between the number of pixels Ngt on a logarithmic scale and the shutter speed adjustment coefficient (S ＳＴ / S Ｓ１ ) is expressed on a logarithmic scale. As can be seen from FIG. 4A, as the number of pixels Ngt increases, the shutter speed S Ｓ１ Therefore, as the number of pixels Ngt increases, the shutter speed adjustment coefficient (S ＳＴ / SＳ１ ) becomes smaller.

[0036] The number of pixels Ngt is one of the features of the light-section image obtained from the sample, and the shutter speed adjustment coefficient (S ＳＴ / S Ｓ１ ) is one of the adjustment information for adjusting the shutter speed. That is, the "relationship information indicating the relationship between the feature amount of the light-section image obtained from the sample and the adjustment information" is defined, for example, by the graph shown in FIG. 4B.

[0037] The relational information shown in FIG. 4B is the feature amount (number of pixels Ngt) and the exposure condition (shutter speed S Ｓ１ ), and the exposure condition sample value (shutter speed S ＳＴ ) relationship. ＳＴ ) is set to a size such that the maximum brightness of the light-section image does not exceed the saturation level of the light-receiving element that acquires the image, and the position where the brightness distribution in the thickness direction of the light-section image is maximum is not affected by noise.

[0038] Exposure condition sample value (shutter speed S ＳＴ ) is set in this way, the shutter speed S calculated for the object 60 using equation (2) is Ｔ Even if the maximum brightness of the light-section image does not exceed the saturation level, the condition that the position where the brightness distribution in the thickness direction of the light-section image is maximum is of a size that is not affected by noise is satisfied.

[0039] Next, the inspection method according to the first embodiment will be described with reference to Fig. 5. Fig. 5 is a flow chart showing the procedure of the inspection method according to the first embodiment.

[0040] First, an image of the object 60 is acquired by setting the shutter speed to a first shutter speed (step SA1). Next, a feature quantity of the light-section image in the acquired image is calculated (step SA2). As this feature quantity, the number Ngt of pixels whose luminance is equal to or greater than the determination threshold Bth in the luminance distribution 31 (FIGS. 3B and 3D) in the thickness direction of the light-section image can be used.

[0041] Next, an appropriate shutter speed during inspection is calculated from the calculated feature amount, the first shutter speed when step SA1 is executed, and the related information (FIG. 4B) stored in the storage unit 41 (step SA3). For example, a shutter speed adjustment coefficient (S ＳＴ / S Ｓ１ ) is determined. ＳＴ / S Ｓ１ ) is determined, the shutter speed S Ｔ Here, the shutter speed S in equation (2) is calculated. １ corresponds to the first shutter speed, and the shutter speed S Ｔ corresponds to the shutter speed during inspection. Next, the obtained shutter speed during inspection S Ｔ Then, the actual inspection is carried out (step SA4).

[0042] Next, the advantageous effects of the first embodiment will be described. In the first embodiment, by setting the shutter speed to a first shutter speed and acquiring an image of the surface to be inspected of the object 60 (step SA1), an appropriate inspection shutter speed can be immediately determined without repeated trial and error (step SA3). For example, as the horizontal axis of FIG. 4A represents shutter speed on a logarithmic scale, the shutter speed must be changed by approximately 1 / 100 to 100 times during trial and error. This can result in a huge number of trial and error iterations. In the first embodiment, since there is no need to repeat trial and error to find an appropriate shutter speed, inspection efficiency can be improved.

[0043] In the first embodiment, an example of inspecting the inner peripheral surface of a cylindrical object 60 is shown, but the method of adjusting the exposure conditions applied to the inspection method according to the first embodiment can be applied to inspections using the more general light-section method. The inspection method according to the first embodiment can also be applied to measuring the shape of the outer surface of an object.

[0044] Next, a modified example of the first embodiment will be described. In the first embodiment, shutter speed is used as the exposure condition to be adjusted. However, aperture value or gain may also be used. In this case, the relationship between aperture value or gain and the number of pixels Ngt may be used instead of the relationship between shutter speed and the number of pixels Ngt shown in FIG. 4A. The relationship between the number of pixels Ngt and aperture value adjustment coefficient, or the relationship between the number of pixels Ngt and gain adjustment coefficient may be defined as the relationship information shown in FIG. 4B. More generally, the relationship between the number of pixels Ngt and the exposure condition adjustment coefficient may be defined as the relationship information. Note that shutter speed can be easily adjusted within a range of, for example, 10 μs to 1 s, providing a wider adjustable range than aperture value or gain. Therefore, using shutter speed as the exposure condition to be adjusted is advantageous in that it provides a wider adjustable range for the exposure condition.

[0045] When any one of shutter speed, aperture value, and gain is used as the exposure condition, in step SA1, an image of the inspection surface of the object 60 is acquired under the first exposure condition. In step SA3, a second exposure condition is determined based on relationship information indicating the relationship between the feature amount (number of pixels Ngt) and adjustment information, the feature amount of the light-section image in the acquired image, and the first exposure condition. In step SA4, an image of the inspection surface of the object is acquired under the second exposure condition, and inspection is performed.

[0046] In the first embodiment, the brightness of the light-section image that can obtain high inspection accuracy is changed by adjusting the exposure conditions of the imaging device 12. Alternatively, the brightness of the light-section image can be changed by adjusting the output of the laser light source 15.

[0047] In the first embodiment, the feature quantity of the light-section image is the number Ngt of pixels that have a luminance equal to or greater than the judgment threshold Bth among the pixels that make up the light-section image, but other feature quantities may also be used. For example, it is possible to use a feature quantity that monotonically increases or decreases with respect to the shutter speed, as shown in the graph of FIG. 4A.

[0048] For example, statistics such as the average value, median, variance, and standard deviation of the luminance values ​​of all pixels constituting the light-section image or all pixels in a ring-shaped region including the light-section image can be used as the feature of the light-section image.

[0049] Alternatively, the values ​​described below may be used as feature quantities. The light-section image is actually composed of multiple arc-shaped images separated in the circumferential direction due to light being blocked by components such as the member supporting the mirror 11B (FIG. 2) and the optical module fixing member 13 (FIG. 1). For each of the multiple arc-shaped images, the contours of areas with brightness values ​​equal to or greater than a threshold are determined. It is also possible to extract contours containing a certain number of pixels or more within the area, and use the ratio of the total number of pixels in the areas surrounded by these contours to the total perimeter of these contours as feature quantities of the light-section image.

[0050] Second Embodiment Next, an inspection device according to a second embodiment will be described with reference to Figures 6 and 7. Below, a description of the components common to the inspection device according to the first embodiment (Figures 1 to 5) will be omitted.

[0051] 6 and 7 are schematic diagrams of an inspection device according to a second embodiment. In the first embodiment (FIG. 1), the optical probe 10 waits above the object 60 when not performing an inspection. In the inspection device according to the second embodiment, the optical probe 10 waits below the object 60 (below the support plate 51), and during inspection, the optical probe 10 rises and enters the space inside the object 60. A user inserts or removes the object 60 into the housing 50 through an opening 50C provided in the housing 50.

[0052] The support mechanism 18 realizes an inserted state in which at least a portion of the optical probe 10 is disposed inside the cylindrical portion of the object 60, and a standby state in which the optical probe 10 is disposed outside the cylindrical portion. Fig. 6 shows the inspection device when the optical probe 10 is in the inserted state, and Fig. 7 shows the inspection device when the optical probe 10 is in the standby state. The inspection device according to the second embodiment is equipped with an access prevention device that prevents a user from accessing the object 60 when the optical probe 10 is in the inserted state. The access prevention device will be described in detail below.

[0053] The access prevention device prevents a user from accessing an object 60 installed in an inspection device. For example, if a user removes the object 60 while the optical probe 10 is inserted, there is a risk that the object 60 will come into contact with the optical probe 10 and damage the optical probe 10. If the user's access to the object 60 is prevented while the optical probe 10 is inserted, damage to the optical probe 10 is prevented.

[0054] The inspection device includes an alarm 71 as one of the access prevention devices. The operation of the alarm 71 is controlled by the control unit 40. When the optical probe 10 is in the inserted state, the alarm 71 notifies the user that the optical probe 10 is in the inserted state. For example, a warning light that lights up red and green lights is used as the alarm 71. When the optical probe 10 is in the inserted state ( FIG. 6 ), the alarm 71 lights up or flashes a red light, and when the optical probe 10 is in the standby state ( FIG. 7 ), the alarm 71 lights up a green light.

[0055] The user can easily notice whether the optical probe 10 is in the inserted state or the standby state by checking the lighting color of the alarm 71. When the user notices that the lighting color of the alarm 71 is red, he or she should be careful not to access the target object 60. This prevents damage to the optical probe 10.

[0056] The inspection device is equipped with a door 54 that blocks the opening 50C of the housing 50 as one of the access prevention devices. A user accesses the object through the opening 50C. The door 54 can be opened, closed, and locked. A sliding door, a swing door, or the like can be used as the door 54. The control unit 40 locks and unlocks the door 54. When the optical probe 10 is in an inserted state, the door 54 is locked, and when the optical probe 10 is in a standby state, the door 54 is unlocked.

[0057] When the optical probe 10 is in the inserted state, the door 54 is locked, and therefore the user cannot open the door 54 to access the target object 60. This prevents the optical probe 10 from being damaged.

[0058] The inspection device includes, as one of the access prevention devices, a detector 72 that detects an object entering the housing 50 through the opening 50C, and an alarm emitter 73. The control unit 40 operates the alarm emitter 73 based on the detection result of the detector 72. When the detector 72 detects an object entering the housing while the optical probe 10 is in the inserted state, the alarm emitter 73 emits an alarm. The detector 72 may be, for example, a light curtain or an area sensor. The alarm emitter 73 may be, for example, a sound emitter that outputs an alarm sound. In addition to the sound emitter, a display or the like that displays an image to alert the user may be provided.

[0059] When maintenance is performed, the door 54 is left open and unlocked. If the detector 72 detects an object entering the housing while the optical probe 10 is inserted, the alarm emitter 73 emits an alarm, so that the user realizes that the optical probe 10 is inserted and stops accessing the target object 60. This prevents damage to the optical probe 10.

[0060] Regardless of whether the optical probe 10 is in the inserted state or the standby state, when the detector 72 detects an object entering the housing, a sound may be emitted to alert the user. The user will be encouraged to work carefully, taking into consideration the possibility that the target object 60 may come into contact with the optical probe 10. This will prevent damage to the optical probe 10.

[0061] Third Embodiment Next, an inspection device according to a third embodiment will be described with reference to Fig. 8. Below, a description of the components common to the inspection device according to the first embodiment (Figs. 1 to 5) will be omitted.

[0062] The control unit 40 (FIG. 1) of the inspection device according to the third embodiment has a function of acquiring the lot ID of the object 60. The lot ID can be acquired by a method in which the user reads the engraved characters affixed to the object 60 and manually inputs the same, a method in which a camera captures the engraved characters and performs image analysis, a method in which a barcode affixed to the object 60 is read, a method in which an IC tag attached to the object 60 is read, or the like.

[0063] 8 is a flowchart showing the procedure for an inspection performed by the inspection apparatus according to the third embodiment. The control unit 40 determines whether or not other objects 60 in the same lot as the object 60 to be inspected next have already been inspected (step SB1). If the objects 60 in the same lot have not yet been inspected, the inspection is performed using the same procedure as steps SA1 to SA4 in FIG. 5.

[0064] If an inspection has already been performed on an object 60 from the same lot as the object 60 to be inspected next, the control unit 40 performs the inspection under the same inspection shutter speed conditions as those used when inspecting the object 60 from the same lot (step SB2).

[0065] Next, the advantageous effects of the third embodiment will be described. Since the inspection method according to the first embodiment ( FIG. 5 ) is applied to the inspection of the first object 60 in the same lot, the inspection can be completed in a short time without repeated trial and error. Since the second and subsequent objects 60 in the same lot are inspected under the exposure conditions that have already been adjusted, the inspection time can be further reduced. Since the objects 60 in the same lot are expected to have a certain degree of uniformity in quality, the inspection shutter speed determined when inspecting the first object 60 can be applied to the second and subsequent objects 60.

[0066] Next, a description will be given of an inspection apparatus according to a modification of Example 3. In Example 3, the shutter speed is used as the exposure condition to be adjusted, but other factors such as aperture value and gain may also be used.

[0067] The above-described embodiments are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. Similar effects resulting from similar configurations of multiple embodiments will not be mentioned sequentially for each embodiment. Furthermore, the present invention is not limited to the above-described embodiments. For example, it will be obvious to those skilled in the art that various modifications, improvements, combinations, etc. are possible.

[0068] REFERENCE SIGNS LIST 10 Optical probe 11 Optical module 11A Collimating lens 11B Mirror 12 Imaging device 13 Optical module fixing member 15 Laser light source 16 Optical fiber 18 Support mechanism 20 Annular beam 21 Diffuse reflection area 22 Reflected light 30 Light section image 31 Brightness distribution 40 Control unit 41 Memory unit 42 Control box 50 Housing 50C Opening 51 Support plate 51A Opening 52 Workpiece placement section 53 Wheels 54 Door 60 Object 71 Alarm 72 Detector 73 Alarm generator

Claims

1. An inspection device comprising: an optical probe that generates an image of an object's surface to be inspected; a memory unit that stores relationship information indicating the relationship between feature amounts of multiple light section images obtained by imaging the sample's surface to be inspected under multiple exposure conditions and adjustment information that adjusts the exposure conditions so that each feature amount of the multiple light section images of the sample approaches a target value; and a control unit that controls the optical probe, wherein the control unit operates the optical probe under a first exposure condition to obtain an image of the object's surface to be inspected; determines a second exposure condition based on the feature amounts of the light section images in the obtained image, the relationship information stored in the memory unit, and the first exposure condition; and operates the optical probe under the second exposure condition to obtain an image of the object's surface to be inspected.

2. An inspection device according to claim 1, wherein the object includes a cylindrical portion, and further comprising: a support mechanism that supports the optical probe and realizes an inserted state in which at least a portion of the optical probe is disposed inside the cylindrical portion, and a standby state in which the optical probe is disposed outside the cylindrical portion; and an access prevention device that prevents a user from accessing the object when the optical probe is in the inserted state.

3. The inspection device according to claim 2, wherein the access prevention device includes an alarm that notifies a user when the optical probe is in the inserted state.

4. An inspection device as described in claim 2 or 3, further comprising a housing that defines a space for accommodating the object and has an opening through which a user can access the object, wherein the access prevention device includes an openable, lockable door that blocks the opening, and wherein the control unit locks the door when the optical probe is in the inserted state and unlocks the door when the optical probe is in the standby state.

5. An inspection device as described in claim 4, wherein the access prevention device includes a detector that detects an object entering the housing through the opening, and an alarm emitter that emits an alarm when the detector detects an object entering the housing while the optical probe is in the inserted state.

6. An inspection method comprising: acquiring an image of an object's surface to be inspected under a first exposure condition; determining a second exposure condition from relationship information indicating the relationship between feature amounts of a plurality of light-section images obtained by imaging the sample's surface to be inspected under a plurality of exposure conditions and adjustment information for adjusting the exposure conditions so that each feature amount of the plurality of light-section images of the sample approaches a target value; the feature amounts of the light-section images in the acquired image; and the first exposure condition; and acquiring an image of the object's surface to be inspected under the second exposure condition.

7. An inspection method according to claim 6, wherein the relationship information includes the feature amounts and exposure conditions when light-section images of the sample are acquired under various exposure conditions, and the relationship between the exposure condition sample values ​​when a light-section image suitable for inspection of the sample is obtained.

8. An inspection method according to claim 7, wherein the exposure condition sample value is set to a size such that the maximum brightness of the light-section image does not exceed the saturation level of the light-receiving element that acquires the image, and the position where the brightness distribution in the thickness direction of the light-section image is maximum is not affected by noise.

9. An inspection device comprising: an optical probe that generates an image of the object's surface to be inspected; a memory unit that stores relationship information indicating the relationship between feature amounts of a light section image obtained from a sample and adjustment information for adjusting the exposure conditions at that time to more suitable exposure conditions; and a control unit having a function to control the optical probe and a function to acquire the lot ID of the object to be inspected next, wherein the control unit, if an object with the same lot ID as the object to be inspected next has not yet been inspected, operates the optical probe under first exposure conditions to acquire an image of the object's surface to be inspected, determines second exposure conditions based on the feature amounts of the light section image in the acquired image, the relationship information stored in the memory unit, and the first exposure conditions, operates the optical probe under the second exposure conditions to acquire an image of the object's surface to be inspected, and if an object with the same lot ID as the object to be inspected next has already been inspected, acquires an image of the object's surface to be inspected under the same exposure conditions as the second exposure conditions applied when the object with the same lot ID was inspected.

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