JP2009063383A - Inspection device and inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection device capable of also detecting a color irregularity flaw with sensitivity, simultaneously with undulation, fine unevenness or foreign matters and a crack-like flaw, in an inspection optical system using a telecentric optical system, and to provide an inspection method. <P>SOLUTION: In the inspection device equipped with an optical element for guiding the irradiation light from a white spot light source to an inspection target to make the reflected light which returns from the surface of the inspection target converge, and the aperture iris arranged at the after-image space focal plane position of the optical element; and an image detection means for detecting the image of the reflected image passing through the aperture iris, the aperture iris is constituted, by arranging a plurality of color filters different in transmission wavelength band in a concentric circular state, wherein the image detection means has a flaw detection means which receives light, in a state where the light transmitted through a plurality of the color filters is separated and detects flaws from the independent image and combined image obtained by the image detection means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inspection apparatus and an inspection method for detecting unevenness, foreign matter, scratches, shading unevenness, and the like on the surface of an object.

[Overview of conventional technology]
With reference to FIG. 15, the prior art disclosed in Patent Document 1 will be described.
The light source device 60 uses a halogen lamp 61 as a light source. The light emitted from the halogen lamp 61 is reflected by an elliptical reflector 62 formed of a dichroic mirror, passes through a heat ray absorption filter 63, and is collected in a pinhole 64 having a diameter of 2 mm. The pinhole 64 serves as a point light source for irradiation light to illuminate the sample surface 74a. A turret-shaped wavelength selection filter 65 including a plurality of interference filters is provided in front of the pinhole 64, and the wavelength of irradiation light for illuminating the sample surface can be appropriately changed. This wavelength selection filter 65 is used to adjust the sensitivity of the optical system portion of the inspection apparatus, and when the peak-to-valley of the unevenness of the sample surface 74a is small, a region having a short wavelength is selected. Irradiation light from the light source device 60 is reflected by the half mirror 75 and then enters the collimating lens 73. The collimating lens 73 is an apochromatic lens having a diameter of 6 inches (F7.1) using a special low dispersion glass. The collimating lens 73 converts the irradiation light diffusing from the pinhole 64 of the light source device 50 into a parallel light beam to form a sample surface 74a. Make it incident. That is, the collimating lens 73 is installed so that the pinhole 64 is located at the position of the front image space focal plane. A sample 74 on which a parallel light beam from the collimating lens 73 is incident is placed on a tilt stage 77. The tilt stage 77 finely adjusts the tilt of the sample 74 so that the parallel light flux of the irradiation light is incident on the sample surface 74a perpendicularly. The reflected light from the sample surface 74a is incident again on the collimating lens 73 and the beam diameter is reduced. The reflected light whose beam diameter is reduced by the collimator lens 73 is transmitted through the half mirror 75 and branched from the optical path of the incident light. The half mirror 75 is a flat plate beam splitter, but is a half mirror with a wedge in which a predetermined minute angle is provided between the two planes. Therefore, unnecessary ghost light generated due to reflection on the upper transmission surface deviates from the optical path of the reflected light, that is, the optical axis of the collimating lens 73. As a result, the ghost light is not detected by the detection device 70. The minute angle provided in the half mirror 75 is set, for example, so that ghost light does not enter the detection device 70 (so that the ghost light is blocked by the entrance pupil of the camera lens 72 of the detection device 70). Necessary reflected light branched from the optical path of the irradiation light by the half mirror 75 enters a zoom type camera lens 72 provided in the detection device 7. An aperture stop 76 is disposed at the condensing position inside the camera lens 72. That is, the aperture stop 76 is disposed at a position corresponding to the rear image space focal plane of the collimating lens 73. Therefore, most of the scattered light scattered on the sample surface 74 a is blocked by the aperture stop 76. The aperture stop 76 is an iris stop composed of 10 blades, and the diameter of the circular opening can be continuously changed by moving the movable adjustment portion. By changing the diameter of the circular opening, a light image suitable for the type of inspection (swell inspection, dimple inspection, scratch inspection, etc.) can be obtained. The reflected light from the sample surface 74 a that has passed through the camera lens 72 is projected onto the detection surface 71 a of the ½ inch type CCD camera 71. The image signal from the CCD camera 71 is once converted into an electrical signal, processed by an appropriate signal processing device, and then sequentially displayed on a monitor (not shown) as a reconstructed image. In this case, the image projected onto the detection surface 71a of the CCD camera 71 is a two-dimensional light / dark pattern corresponding to the state of the sample surface 74a. More specifically, the light / dark pattern of the image projected on the detection surface 71a of the CCD camera 71 is composed of only the reflected light from the sample surface 74a that has passed through the aperture stop 76. That is, most of the scattered light that is not reflected in the normal direction on the sample surface 74 a is blocked by the aperture stop 76, and the return light that is reflected in the normal direction on the sample surface 74 a passes through the aperture stop 76. To do. Moreover, the light projected at each position in the light / dark pattern constituted by the return light has a one-to-one correspondence with each position on the sample surface 74a. Therefore, the light / dark pattern of the image projected on the detection surface 71a of the CCD camera 71 reflects a minute change such as the unevenness of the sample surface 74a. By observing the image output of the CCD camera 71, A two-dimensional distribution of minute changes in the state of the sample surface 74a can be accurately observed.

[Problems of the prior art]
In the conventional optical system using the telecentric optical system as described above, when the number of defect types to be detected increases, it is necessary to change the size of the aperture stop and perform imaging a plurality of times. For example, consider optical disk inspection. FIG. 1 shows a layer structure of a conventional reflection type optical disc. In FIG. 1, an optical disc 1 is composed of a circular substrate 2, a recording layer 3 formed on the lower surface of the substrate 2, and a reflective layer 4 formed by evaporating gold on the surface of the recording layer 3, for example. As a material for the substrate 2, a light transmissive member such as glass or polycarbonate is mainly used. The recording layer 3 is formed by applying an organic dye on the substrate 2 by spin coating. Furthermore, a protective film 5 or a film having other functions may be formed on the surface of the recording layer 3. In the inspection of such an optical disk, it is necessary to detect defects such as irregularities and scratches on the surface of the substrate 2 and the surface of the reflective layer 4 and mixed foreign matter. When the conventional technique is applied to such an inspection, it is possible to increase the detection sensitivity for unevenness, scratches, and foreign matter by reducing the aperture stop to a small size. However, on the other hand, the recording layer 3 is formed of a dye, and there are uneven defects due to the difference in density. Such color information (color density) is usually obtained by receiving diffused light. In other words, the larger the aperture stop is, the easier it is to receive diffused light, which makes it more sensitive to color changes. Therefore, when it is desired to inspect the unevenness of the surface of the object and the difference in color at the same time, it is necessary to change the size of the aperture stop and perform imaging a plurality of times.

Next, FIG. 7 shows the structure of a photoconductor (Organic Photo Conductor) drum 17. An undercoat layer (UC layer: Under Coat Layer) 19 is coated on the cylindrical aluminum tube 18, and further, a charge generation layer (CG layer: Charge carrier Generation Layer) 20 and a charge transport layer (CT layer: Charge carrier Transfer). A three-layer structure in which Layer 21 is coated is common. As shown in FIG. 8, the types of defects generated include foreign matter 27 generated inside the three-layer structure, shading unevenness 28 due to coating unevenness, scratches 26 caused by contact with the drum surface layer, attached foreign matter, CT layer 21. Film thickness unevenness 25 or the like generated when the thickness of the film is different from the normal part. Even when the conventional technique is applied to such inspection of the photosensitive drum 17, the film thickness unevenness 25, the scratch 26, and the foreign matter 27 can increase the detection sensitivity as the aperture stop is reduced. On the other hand, the sensitivity decreases.
Japanese Patent No. 3385432

  The present invention has been made in view of the above circumstances, and in an inspection optical system using a telecentric optical system, simultaneously detects defects such as undulations, subtle irregularities, foreign matters, scratches, and color unevenness defects with high sensitivity. An object of the present invention is to provide an inspection apparatus and inspection method that can be used.

  In order to achieve such an object, the first inspection apparatus of the present invention guides the irradiation light from the white point light source to the inspection object, and focuses the reflected light returning from the surface of the inspection object. And an aperture stop disposed at the focal plane position of the rear image space of the optical element, and image detection means for detecting an image of reflected light that has passed through the aperture stop, the aperture stop has a transmission wavelength A configuration in which a plurality of color filters having different bands are arranged concentrically, and the image detecting means receives light in a state where light transmitted through the plurality of color filters is separated, and a single image and a combination obtained by the image detecting means It has a defect detection means for detecting a defect from the obtained image.

  The second inspection apparatus of the present invention is the first inspection apparatus of the present invention for guiding the irradiation light from the white point light source to the inspection object and focusing the reflected light returning from the inspection object surface. An inspection apparatus comprising: an optical element; a first aperture stop disposed at a focal plane position of a rear image space of the optical element; and an image detection unit that detects an image of reflected light that has passed through the first aperture stop. A second aperture stop having a configuration in which a plurality of color filters having different transmission wavelength bands are arranged concentrically at a point light source position conjugated with the first aperture stop. It is characterized by having defect detection means for receiving light in a state where light transmitted through the filter is separated and detecting defects from a single image and a combined image obtained by the image detection means.

  According to a third inspection apparatus of the present invention, in the first or second inspection apparatus of the present invention, the plurality of color filters are a color filter that passes only R color, a color filter that passes only G color, and only B color. And a color filter that allows the light to pass therethrough.

  According to a fourth inspection apparatus of the present invention, in any one of the first to third inspection apparatuses of the present invention, the defect detection means first detects defects using only the G image detected by the image detection means. Next, a G + B image is generated by adding the B image detected by the image detection means and the G image, defect detection is performed using the G + B image, and then the detection is performed by the image detection means A G + B + R image obtained by adding the R image and the G + B image is generated, and defect detection is performed using the G + B + R image.

  According to a fifth inspection apparatus of the present invention, in any one of the first to fourth inspection apparatuses of the present invention, the inspection apparatus includes an identification unit that identifies a type of defect detected by the defect detection unit.

  According to a sixth inspection apparatus of the present invention, in any one of the first to fifth inspection apparatuses of the present invention, the inspection apparatus includes a display unit that displays a detection result by the defect detection unit.

  According to a seventh inspection apparatus of the present invention, in any one of the first to sixth inspection apparatuses of the present invention, the image detecting means is either a single-plate color CCD or a 3 CCD color camera. .

  An eighth inspection apparatus according to the present invention includes an optical element for guiding irradiation light from a light source to an inspection object and focusing reflected light returning from the surface of the inspection object, and a rear image space focal plane of the optical element. An inspection apparatus comprising: an aperture stop disposed at a position; and an image detection unit that detects an image of reflected light that has passed through the aperture stop. The aperture stop has a configuration in which a plurality of polarizing filters having different polarization states are concentrically arranged, and the detection means receives the light branched by the optical path branching means, respectively, and a single image obtained by the image detection means And defect detection means for detecting a defect from the combined image.

  According to a ninth inspection apparatus of the present invention, in the eighth inspection apparatus of the present invention, the plurality of polarizing filters include a first polarizing filter that transmits the first linearly polarized light of the light source, and a second linearly polarized light of the light source. And a second polarizing filter that transmits the light.

  According to a tenth inspection apparatus of the present invention, in the eighth or ninth inspection apparatus of the present invention, the defect detection means first performs defect detection using only the first polarized image detected by the image detection means. Next, a first + second polarization image is generated by adding the second polarization image detected by the image detection means and the first polarization image, and the first + second polarization image is used. Defect detection is performed.

  An eleventh inspection apparatus according to the present invention is characterized in that, in any one of the eighth to tenth inspection apparatuses according to the present invention, the inspection apparatus includes an identification unit that identifies a type of a defect detected by the defect detection unit.

  According to a twelfth inspection apparatus of the present invention, in any one of the eighth to thirteenth inspection apparatuses of the present invention, the inspection apparatus includes a display unit that displays a detection result by the defect detection unit.

  In the first inspection method of the present invention, the irradiation light from the white point light source is guided to the inspection object, the reflected light returning from the surface of the inspection object is focused, and a plurality of color filters having different transmission wavelength bands are concentric. A single image obtained by a plurality of color filters, which is received in a state where light transmitted through a plurality of color filters is separated and transmitted through an aperture stop installed at the position of the focal plane of the rear image space. The defect is detected from the image and the combined image.

  In the second inspection method of the present invention, the irradiation light from the white point light source is guided to the inspection object through a diaphragm in which a plurality of color filters having different transmission wavelength bands are concentrically arranged, and returns from the surface of the inspection object. The reflected light is focused, passed through an aperture stop installed at the position of the focal plane of the rear image space, and received from a plurality of color filters in a separated state. Defects are detected from the image and the combined image.

  According to the third inspection method of the present invention, the irradiation light from the light source is guided to the inspection object, the reflected light returning from the surface of the inspection object is focused, and a plurality of polarizing filters having different polarization states are arranged concentrically. From the single image and the combined image obtained by each polarizing filter, after passing through the aperture stop installed at the position of the focal plane of the rear image space, separating the optical path by the difference in polarization state, and receiving light It is characterized by detecting a defect.

  According to the present invention, an aperture stop having a configuration in which a plurality of color filters having different transmission wavelength bands are arranged concentrically at the rear image space focal plane position is disposed, and the light transmitted through each color filter is received in a separated state. Therefore, it is possible to simultaneously perform imaging with a plurality of sizes of openings, that is, it is possible to simultaneously perform different types of defects with one imaging.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

As Example 1 of the present invention, an inspection apparatus and an inspection method for detecting defects or the like of an optical disk will be described.
In FIG. 2, the light from the white light source 6 is condensed on the illumination light stop 8 by the condenser lens 7 and reflected by the half mirror 9. Since the illumination light stop 8 is disposed at the focal point of the collimating lens 10, the collimating lens 10 converts the illumination light into a parallel light beam and irradiates the optical disk 1. The reflected light from the optical disk 1 passes through the collimating lens 10 and the half mirror 9, passes through the color filter aperture stop 11, and forms an image on the element surface of the single-plate color CCD 12. As shown in FIG. 2, the color filter aperture stop 11 is disposed at the rear focal position of the collimating lens 10 and the imaging optical system is telecentric on the optical disc 1 side. The image of the optical disk 1 picked up by the single-plate color CCD 12 is taken into the image input unit 13 and subjected to image processing by the image processing unit 14. The inspection result obtained by the image processing unit 14 is displayed on the monitor 15.

  In the single-plate color CCD 12, a color filter as shown in FIG. 4 is used. The Bayer arrangement is such that G having a large contribution ratio of the luminance signal is arranged on the checkered pattern, and R and B are further arranged on the checkered pattern in the remaining portions. At the time when a signal is output from a CCD covered with such a color filter such as a Bayer array, only information for one color among the RGB color components is obtained for each pixel. Therefore, in normal imaging, interpolation processing for obtaining the remaining color information is performed by estimating information for the remaining two colors for each pixel from the color signal values of the peripheral pixels in the image processing unit.

  The color filter aperture stop 11 is configured as shown in FIG. That is, the color filter 11 (a) that passes only G from the center, the color filter 11 (b) that passes only B, and the color filter 11 (c) that passes only R are formed concentrically.

  A method for detecting a defective portion from the image obtained by the color filter aperture stop 11 and the single-plate color CCD 12 will be described with reference to FIG. The R, G, and B images 29, 30, and 31 obtained by the image input unit 13 are sent to the image processing unit 14. First, the image processing unit 14 performs defect detection processing using only the G image 29. That is, if there is no defect on the optical disc 1, the reflected light can pass through the color filter aperture stop 11 (a). However, if the surface has irregularities due to waviness or the like, the reflected light deviates from the normal direction, and thus cannot pass through the color filter aperture stop 11 (a). Further, even when light is scattered by foreign matter or scratches, the scattered light cannot pass through the color filter aperture stop 11 (a). As a result, the bright and dark pattern of the G image 29 obtained by the single-plate color CCD 12 reflects a minute change such as the unevenness of the optical disk 1. In the defect detection process 1 (34), for example, the video signal (original video signal) included in the G image 29 is differentiated, the average or standard deviation is calculated by dividing into rectangular areas, and the defect is analyzed by a histogram analysis. Part can be detected. Since the G image 29 is an image obtained in a state where the opening is the smallest, the detection sensitivity to the unevenness is the highest.

  Next, the G image 29 and the B image 30 obtained by the image input unit 14 are added to generate a G + B image 32. The G + B image 32 represents a light / dark pattern by reflected light that can pass through the color filter aperture stops 11 (a) and 11 (b) in FIG. 3 and reflected light that cannot pass. The defect detection processing unit 2 (35) detects the defective part by the same method as the defect detection processing unit 1 (34). In this case, since the opening has a size obtained by combining 11 (a) and (b), the detection sensitivity to the unevenness is lower than that of the G image 29 alone. Furthermore, the G + B + R image 33 is generated by adding the R image 31 obtained by the image input unit 14 to the G + B image 32. From this G + B + R image 33, the defect detection processing unit 3 (36) detects the defective part by the same method as the defect detection processing unit 1 (34). Here, the size of the color filter aperture stop 11 (c) is set to a level that can sufficiently receive the scattered light from the recording layer 3 of the optical disc 1. Here, the detection sensitivity with respect to the unevenness can be lowered, and the uneven density of the recording layer 3 can be detected with high sensitivity.

  Next, the operation of the identification unit 37 will be described. Let us consider a case where a dent defect whose incident light is not scattered and a foreign object or scratch that scatters incident light is identified without being scattered. When the aperture stop is enlarged, the dent defect cannot be detected first. In the case of foreign matter or scratches in which incident light is scattered, the scattered light remains dark because it cannot pass even if the opening is slightly expanded. Therefore, if the opening is set to a limit size that can detect the dent defect with the size of 11 (a) as a target, the G image 29 and the defect detection processing unit 1 (34) will dent, foreign matter, scratches. , Foreign matter and scratches can be detected by the G + B image 32 and the defect detection processing unit 2 (35).

  In the identification unit 37, it is determined that what is detected by both is a scattering defect such as a foreign object or a flaw, and that only the defect detection processing unit 1 (34) detects a defect such as a dent. Are identified, the determination result is stored, color-coded, etc., and displayed on the monitor 15. Similarly, a defect detected only by the defect detection processing unit 3 (36) can be determined to be an uneven density defect. As described above, it is possible to identify defect types having different properties and causes of occurrence, such as dents, foreign matters, scratches, and shading unevenness.

As an embodiment 2 of the present invention, an inspection apparatus and an inspection method for detecting a defect or the like of a photosensitive drum will be described.
In FIG. 9, the light emitted from the white light source 6 is condensed at the position of the illumination light stop 8 by the condenser lens 7 to form an image of the white light source 6, and the light that has passed through the illumination light stop 8 is substantially The illumination light is considered to be from a point light source. The illumination light is incident on the half mirror 9 via an illumination lens (cylindrical lens) 22, reflected by the half mirror 9, and then irradiated toward the photosensitive drum 17.

  The reflected light reflected by the photosensitive drum 17 passes through the half mirror 9 and is collected by the imaging lens 23 and forms an image on the single-plate color CCD 12. Here, the photosensitive drum 17 is disposed so that the center 24 of the cylindrical photosensitive drum 17 exists on the optical axis, and further, the point 38 and the center 24 where the photosensitive drum 17 and the optical axis intersect with each other. The photosensitive drum 17 is arranged so that the middle point (focal point of spherical surface) 39 substantially coincides with the condensing point of the illumination light without the photosensitive drum 17.

  By arranging the photosensitive drum 17 in this way, the reflected light becomes substantially parallel light and enters the imaging lens 23 along the optical axis, and forms an image of the photosensitive drum 17 on the single-plate color CCD 12. . The color filter aperture stop 11 is disposed at the rear image space focal position of the imaging lens 23. When minute irregularities, scratches, foreign matter, etc. exist on the photosensitive drum 17, a light and dark pattern appears on the single-plate color CCD 12 corresponding to the minute irregularities, scratches, foreign matter, etc.

  The configuration of the color filter aperture stop 11 is the same as that of the first embodiment described above (see FIG. 3). The processing method for detecting a defective portion from R, G, and B images obtained by the single-plate color CCD 12 is also the same as that in the first embodiment.

  In the first and second embodiments, the single-plate color CCD 12 is used, but a 3CCD color camera shown in FIG. 5 may be used. In this case, there is no color filter as shown in FIG. 4, and the color separation prism 16 divides the image into R, G and B images, which are received by the CCD.

  As described above, according to the first to third embodiments, an aperture stop having a configuration in which a plurality of color filters having different transmission wavelength bands are concentrically arranged is disposed at the focal plane position of the rear image space. Since the light transmitted through is received in a separated state, it is possible to simultaneously perform imaging with a plurality of apertures, that is, it is possible to simultaneously perform different types of defects with one imaging.

As Example 4 of the present invention, an inspection apparatus having a configuration in which a color filter aperture stop is installed on the illumination side will be described.
As shown in FIG. 11, the inspection apparatus of the present embodiment has a color filter aperture stop (second aperture stop) 11 installed at the position of the illumination light aperture 8 in the configuration of Example 1 (see FIG. 2). In this configuration, an aperture stop (first aperture stop) 57 is installed at the focal position of the imaging lens 23 on the rear image space side. In this configuration, the parallelism of the illumination light varies depending on the size of the color filter aperture stop 11. The detection sensitivity varies depending on the parallelism of the irradiated light.

  The reason will be described with reference to FIG. FIG. 10A shows a case where the size of the color filter aperture stop 11 is small. When the surface of the optical disc 1 is the normal surface 42, the incident light 40 is incident in the normal direction, and the reflected light 41 is also in the normal direction. Reflects. Here, when the surface of the optical disc 1 has a concave-convex defect and has an inclined surface 43 (FIG. 10B), the incident light 40 is incident in the normal direction, while the reflected light 41 is reflected in FIG. Unlike the direction of), the image cannot pass through the aperture stop 57, and an image darkened by the single-plate color camera 12 is obtained.

  Next, when the color filter aperture stop 11 is enlarged, the parallelism of the incident light 40 is disturbed, and light incident from other than the normal direction is mixed as shown in FIGS. 10 (c) and 10 (e). come. In this state, when the inclined surface 43 is irradiated, the reflected light 41 from the inclined surface 43 is reflected in the normal direction as shown in FIG. 42 may be as bright as 42. That is, as the color filter aperture stop 11 is made larger, the sensitivity to unevenness decreases, while color information can be obtained because light diffused by irradiating the object to be inspected at various angles can be received. Therefore, in the same manner as in the first embodiment, the G image 29 with the smallest aperture is used to detect defects such as dents and scattering defects such as foreign matter and scratches, and the G + B image 32 indicates scattering defects such as foreign matter and scratches, and G + B + R images In FIG. 33, the density unevenness defect can be detected.

  As described above, according to the fourth embodiment, a stop having a configuration in which a plurality of color filters having different transmission wavelength bands are arranged concentrically at a point light source position conjugated with an aperture stop is disposed, and each color filter is Since the transmitted light is received in a separated state, it is possible to simultaneously receive and receive irradiation light with different parallelism, that is, it is possible to simultaneously perform different types of defects with one imaging.

An inspection apparatus and an inspection method according to Example 5 of the present invention will be described.
In FIG. 12, the light from the laser light source 44 is spread by the collimating lens 1 (45) and the collimating lens 2 (58), is collimated, and is irradiated onto the optical disc 1. It is assumed that the laser light source 44 is a randomly polarized light, and two linearly polarized light (linearly polarized light 1 and linearly polarized light 2) whose polarization planes are orthogonal are mixed at a ratio of 1: 1. The reflected light from the optical disc 1 passes through the collimating lens 2 (58) and the half mirror 9, passes through the polarizing filter aperture stop 46, and is then split by the polarizing beam splitter 47, and is then sent to the CCD 1 (48) and the CCD 2 (49). Each is imaged.

  Here, the configuration of the polarizing filter aperture stop 46 will be described with reference to FIG. An aperture stop is formed concentrically with the polarizing filter 1 (46 (a)) so that the linearly polarized light 1 of the laser light source 44 is transmitted from the center and with the polarizing filter 2 (46 (b)) so that the linearly polarized light 2 is transmitted. Has been. As shown in FIG. 12, the polarizing filter aperture stop 46 is disposed at the rear focal position of the collimating lens 2 (58). The linearly polarized light 1 that has passed through the polarizing filter 1 (46 (a)) passes through the polarizing beam splitter 47 and forms an image on the CCD 1. On the other hand, the linearly polarized light 2 that has passed through the polarizing filter 2 (46 (b)) is bent by the polarizing beam splitter 47 and forms an image on the CCD 2.

  As shown in FIG. 14, the polarization 1 image 52 and the polarization 2 image obtained by the image input unit 50 are sent to the image processing unit 51. First, the image processing unit 51 performs defect detection processing using only the polarization 1 image 52. That is, if there is no defect on the optical disc 1, the reflected light can pass through the polarizing filter aperture stop 46 (a). However, if the surface has irregularities due to waviness or the like, the reflected light deviates from the normal direction and cannot pass through the polarizing filter aperture stop 46 (a). Even when light is scattered by foreign matter or scratches, the scattered light cannot pass through the polarizing filter aperture stop 46 (a). As a result, the light / dark pattern of the polarized light 1 image 52 reflects a minute change such as unevenness of the optical disk 1.

  In the defect detection process 4 (55), for example, the video signal (original video signal) included in the polarization 1 image 52 is differentiated, the average or standard deviation is calculated by dividing into rectangular areas, and the histogram is analyzed. A defective part can be detected. Since the polarized light 1 image 52 is an image obtained with a small aperture, the detection sensitivity for unevenness is the highest. Next, the polarization 1 image 52 and the polarization 2 image 53 obtained by the image input unit 50 are added to generate a polarization 1 + polarization 2 image 54.

  The polarized light 1 + polarized light 2 image 54 represents a light / dark pattern by reflected light that has passed through the polarizing filter aperture stops 46 (a) and 46 (b) and reflected light that has failed to pass. The defect detection processing unit 5 (56) detects the defective part by the same method as the defect detection processing unit 4 (55). In this case, since the opening has the size of 46 (a) and 46 (b), the detection sensitivity to the unevenness is lower than that of the polarization 1 image 52, but the scattered light from the recording layer 3 of the optical disc 1 is scattered. Is set to a level that can sufficiently receive light. That is, here, the detection sensitivity for unevenness can be reduced, and unevenness in the density of the recording layer 3 can be detected with high sensitivity.

  Next, in the identification unit 59, the defect detected only by the defect detection processing unit 4 (55) is a dent defect, and the defect detected only by the defect detection processing unit 5 (56) is uneven density detection. The defect type is identified as a defect such as a foreign object or a flaw, the defect type is identified, the result is stored, color-coded or the like is applied, and the result is displayed on the monitor 15.

  As described above, according to the fifth embodiment, the aperture stop having the configuration in which a plurality of polarization filters having different polarization states are arranged concentrically at the rear image space focal plane position, and the light transmitted through each polarization filter. Since the light is received in a separated state, it is possible to simultaneously perform imaging with a plurality of sizes of openings, that is, it is possible to simultaneously perform different types of defects with one imaging.

  As mentioned above, although each Example of this invention was described, it is not limited to said each Example, A various deformation | transformation is possible in the range which does not deviate from the summary.

  The present invention can be applied to a defect inspection method and apparatus for optical discs and photosensitive drums.

It is a sectional side view which shows the structure of the optical disk used as the test object of the test | inspection apparatus of this invention. It is a figure which shows the structure of the inspection apparatus which concerns on Example 1 of this invention. It is a figure which shows the color filter aperture stop of the inspection apparatus which concerns on Example 1 of this invention. It is a figure which shows the color filter of a Bayer array of the inspection apparatus which concerns on Example 1 of this invention. It is a figure which shows an example of 3CCD color camera. It is a block diagram which shows the structure of the image processing part of the inspection apparatus which concerns on Example 1 of this invention. FIG. 3 is a view showing a structure of a photoconductor (Organic Photo Conductor) drum 17. It is a figure which shows the kind of defect which generate | occur | produces in a photoconductor drum. It is a figure which shows the structure of the inspection apparatus which concerns on Example 2 of this invention. It is a figure for demonstrating the principle of the inspection apparatus which concerns on Example 4 of this invention. It is a figure which shows the structure of the inspection apparatus which concerns on Example 4 of this invention. It is a figure which shows the structure of the inspection apparatus which concerns on Example 5 of this invention. It is a figure which shows the color filter aperture stop of the inspection apparatus which concerns on Example 5 of this invention. It is a block diagram which shows the structure of the image process part of the inspection apparatus which concerns on Example 5 of this invention. It is a figure which shows the structure of a prior art.

Explanation of symbols

1 Optical disk (inspection object)
2 Substrate 3 Recording layer 4 Reflective layer 5 Protective layer 6 White light source (white point light source)
7 Condenser lens 8 Illumination light stop 9 Half mirror 10 Collimating lens 11 Color filter aperture stop 11 (a) Color filter that passes only G 11 (b) Color filter that passes only B 11 (c) Color filter that passes only C 12 Single Plate type color CCD (image detection means)
13 Image Input Unit 14 Image Processing Unit (Defect Detection Unit)
15 Monitor (display means)
17 Photosensitive drum (inspection object)
18 Aluminum Element Tube 19 UC Layer 20 CG Layer 21 CT Layer 22 Illumination Lens 23 Imaging Lens 24 Center of Photosensitive Drum 17 Film Thickness Unevenness (Example of Defect)
26 Scratches (an example of a defect)
27 Foreign matter (an example of a defect)
28 Light and dark unevenness (an example of a defect)
29 G image 30 B image 31 R image 32 G + B image 33 G + B + R image 34 Defect detection processing 1
35 Defect detection process 2
36 Defect detection process 3
37 Identification part (identification means)
38 Point at which the photoconductor drum 17 and the optical axis cross each other 39 Midpoint of the center 24 of the photoconductor drum 17 (spherical focal point)
40 incident light 41 reflected light 42 normal surface 43 inclined surface 44 laser light source 45 collimating lens 1
46 Polarizing filter aperture stop 46 (a) Polarizing filter 1 (first polarizing filter)
46 (b) Polarizing filter 2 (second polarizing filter)
47 Polarizing beam splitter (optical path branching means)
48 CCD1 (image detection means)
49 CCD2 (image detection means)
50 Image input unit 51 Image processing unit (defect detection means)
52 Polarized 1 image (first polarized image)
53 Two polarized images (second polarized image)
54 Polarized light 1 + polarized light 2 image (first + second polarized image)
55 Defect detection process 4
56 Defect detection processing 5
57 Aperture stop (first aperture stop)
58 Collimating lens 2
59 Identification part (identification means)
60 Light source device 61 Halogen lamp 62 Elliptic reflector 63 Heat ray absorption filter 64 Pinhole 65 Wavelength selection filter 70 Detection device 71 CCD camera 71a Detection surface of CCD camera 71 72 Camera lens 73 Collimating lens 74 Sample 74a Sample surface 75 Half mirror 76 Aperture stop 77 Tilt stage

Claims (15)

An optical element for guiding the irradiation light from the white point light source to the inspection object and focusing the reflected light returning from the surface of the inspection object, and a rear image space focal plane position of the optical element In an inspection apparatus comprising: an aperture stop; and an image detection unit that detects an image of the reflected light that has passed through the aperture stop.
The aperture stop is configured by concentrically arranging a plurality of color filters having different transmission wavelength bands,
The image detecting means receives light that has passed through the plurality of color filters in a separated state,
An inspection apparatus comprising defect detection means for detecting defects from a single image and a combined image obtained by the image detection means. An optical element for guiding the irradiation light from the white point light source to the inspection object and focusing the reflected light returning from the surface of the inspection object, and a rear image space focal plane position of the optical element In an inspection apparatus comprising: a first aperture stop; and an image detection unit that detects an image of the reflected light that has passed through the first aperture stop.
A second aperture stop having a configuration in which a plurality of color filters having different transmission wavelength bands are arranged concentrically at a point light source position conjugated with the first aperture stop;
The image detecting means receives light that has passed through the plurality of color filters in a separated state,
An inspection apparatus comprising defect detection means for detecting defects from a single image and a combined image obtained by the image detection means.   3. The plurality of color filters are composed of a color filter that passes only the R color, a color filter that passes only the G color, and a color filter that passes only the B color. Inspection equipment. The defect detection means includes
First, defect detection is performed using only the G image detected by the image detection means,
Next, a G + B image obtained by adding the B image detected by the image detection means and the G image is generated, and defect detection is performed using the G + B image.
4. The G + B + R image obtained by adding the R image detected by the image detecting means and the G + B image is generated, and defect detection is performed using the G + B + R image. The inspection device according to any one of the above.   5. The inspection apparatus according to claim 1, further comprising an identification unit that identifies a type of defect detected by the defect detection unit.   6. The inspection apparatus according to claim 1, further comprising display means for displaying a detection result by the defect detection means.   The inspection apparatus according to any one of claims 1 to 6, wherein the image detection means is either a single-plate color CCD or a 3CCD color camera. An optical element for guiding irradiation light from a light source to an inspection object and converging reflected light returning from the surface of the inspection object, and an aperture stop disposed at a focal plane position of a rear image space of the optical element And an image detection means for detecting an image of the reflected light that has passed through the aperture stop,
Having optical path branching means for branching the optical path of the bundled light according to the polarization state;
The aperture stop has a configuration in which a plurality of polarizing filters having different polarization states are arranged concentrically.
The detecting means receives the light branched by the optical path branching means,
An inspection apparatus comprising defect detection means for detecting defects from a single image and a combined image obtained by the image detection means.   The plurality of polarizing filters include a first polarizing filter that transmits the first linearly polarized light of the light source, and a second polarizing filter that transmits the second linearly polarized light of the light source. 9. The inspection apparatus according to claim 8, wherein the inspection apparatus is characterized. The defect detection means includes
First, defect detection is performed using only the first polarization image detected by the image detection means,
Next, a first + second polarization image is generated by adding the second polarization image detected by the image detection means and the first polarization image, and the first + second polarization image is used. 10. The inspection apparatus according to claim 8, wherein defect detection is performed.   The inspection apparatus according to claim 8, further comprising an identification unit that identifies a type of defect detected by the defect detection unit.   The inspection apparatus according to any one of claims 8 to 11, further comprising display means for displaying a detection result by the defect detection means. The light emitted from the white point light source is guided to the inspection object, the reflected light returning from the surface of the inspection object is focused, and a plurality of color filters having different transmission wavelength bands are concentrically arranged. Transmit through an aperture stop installed at the position of the focal plane of the image space,
An inspection method, wherein light transmitted through the plurality of color filters is received in a separated state, and a defect is detected from a single image and a combined image obtained by the plurality of color filters.   The irradiation light from the white point light source is guided to the inspection object through a diaphragm in which a plurality of color filters having different transmission wavelength bands are arranged concentrically, and the reflected light returning from the surface of the inspection object is focused, and the rear image Through the aperture stop installed at the position of the spatial focal plane, the light irradiated from the plurality of color filters is received in a separated state, and defects are obtained from the single image and the combined image obtained by the plurality of color filters. The inspection method characterized by detecting.   It has a configuration in which the irradiation light from the light source is guided to the inspection object, the reflected light returning from the surface of the inspection object is focused, and a plurality of polarizing filters having different polarization states are concentrically arranged to focus on the rear image space. Transmitting through an aperture stop installed at a plane position, separating the optical path according to the difference in polarization state, receiving light, and detecting defects from single images and combined images obtained by each polarization filter Inspection method.

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