JPH02208846A - Inspection instrument for optical recording medium - Google Patents

Abstract

PURPOSE:To efficiently perform the inspection of a various kinds of optical characteristics and to precisely obtain an inspection result by providing an image input means to fetch light from a projecting light adjusting means as image informa tion, and an image processing means to inspect the presence/absence of the defect of a recording medium by performing the arithmetic processing of fetched image information at every prescribed section. CONSTITUTION:An optical disk substrate 2 is irradiated with the light from a light source 13, and an image I is fetched by photographing the light transmitting the sub strate 2 with a CCD camera 14, a fetched photographed image I is read in the image processing means 40, and is converted to luminance information Br by a converter 41 at every picture element Px, then, is stored in an image information memory 42. After the fetching of all of the image information in the optical disk substrate 2 are completed, a defect inspection system 1 starts up the image processing means 40, and performs judgement for a processing at every section Sn and a specific part selected from the luminance information Br in the image information memory 42 by a section setting means 32, a mean value calculation means 44, and a comparison deciding means 45. In such a way, it is possible to efficiently perform the defect inspec tion of the recording medium targeted to be inspected, and to surely detect also a fine defect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an inspection device for optical recording media, and can be used for manufacturing and inspecting optical discs and the like that perform optical recording and reproduction.

[Conventional technology]

BACKGROUND ART Conventionally, in recording media such as optical disks that perform optical recording and reproduction, it has been required that substrate materials have high optical properties, are homogeneous, and are stable.

For example, if there is an optical defect such as material unevenness on the substrate of an optical disc, the light beam for recording and reproduction will not pass through or be reflected in the desired state at this part, making it impossible to use it normally as a recording medium. . Therefore, when producing optical discs, etc., it is essential to inspect the optical characteristics and defective parts of the substrate. In particular, in order to avoid the waste of recording on a recording medium using a defective substrate, defect inspection of the substrate is required at an early stage of the manufacturing process.

Conventionally, such optical characteristics have been inspected visually from the substrate surface, and the state of light reflection and transmission is directly compared with, for example, a normal substrate. . In recent years, judgments based on image processing have been adopted in order to automate inspections. For example, an image of a normal board is taken as a reference image, and the board to be inspected is sequentially exposed to IR under the same conditions to create an inspection image. A method has been proposed in which the optical states of corresponding parts are compared, for example, pixel by pixel, and if there is a part in the inspection image that differs from the reference image, it is determined to be a defect.

[Problems to be Solved by the Invention] By the way, there are several types of optical discs, and especially in rewritable optical discs, the optical characteristics required of the substrate differ depending on the recording method. Therefore, when inspecting optical characteristics, it is necessary to change the inspection conditions depending on the required characteristics.

For example, in the magneto-optical recording method, signals are recorded using changes in the plane of polarization depending on the direction of magnetization of the recording layer, and the polarization properties of the substrate are particularly important. For this reason, it is desirable to employ various types of polarized light as the inspection light irradiated onto the substrate and to mainly inspect the polarization characteristics of the substrate. On the other hand, in the phase change recording method, signals are recorded by changes in the reflectance of the recording layer, and the substrate is required to have good reflection characteristics and transmission characteristics. For this reason, it is necessary to take measures such as changing the direction, diffusion state, etc. of the inspection light irradiated onto the substrate, and inspecting mainly the reflection on the substrate surface and the internal transmission characteristics.

Here, when conventional visual inspection is performed, the posture of the substrate can be adjusted, the type of light source can be selected, etc. freely. However, since visual inspection is a human-based judgment, ambiguity is inevitable, and the person in charge of the inspection needs to gain experience to be able to make stable judgments. Furthermore, as boards are frequently handled manually, there is a risk of scratches or dirt on the board surface, and the processing time required to inspect one board is long, resulting in low inspection efficiency. Therefore, it is practically difficult to inspect all of the mass-produced boards.

On the other hand, objective results can be obtained by performing inspections using image processing, but there is no dedicated equipment for projecting light and photographing to capture images of the board, and various polarization settings and adjustments to the degree of light diffusion are required. When performing this, it is necessary to set up inspection equipment each time, which poses problems such as low work efficiency and difficulty in handling a wide variety of optical discs.

In addition, when performing a comparative inspection with a reference image, it is necessary to match the condition settings at the time of inspection with the condition settings of the reference image.
It is necessary to prepare an ideal reference image for each board type.
It is difficult to apply this method to actual manufacturing inspections.

Furthermore, in the above-mentioned comparative inspection, as long as the comparison result between the corresponding parts of the inspection image and the reference image is approximately negative, it is determined to be normal. cannot be reliably detected. On the other hand, in optical discs, etc., the characteristics may be different between the outer periphery and the center, and it is not effective to judge the overall uniformity when inspecting such objects. It has been desired to reliably detect peculiar changes in the area, that is, areas that lack continuity with the surrounding area.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical recording medium inspection apparatus that can efficiently inspect various optical characteristics and provide accurate inspection results.

[Means for Solving the Problems] The present invention provides a light source for irradiating light onto an optical recording medium to be inspected, an inspection light adjusting means for adjusting optical characteristics of the light irradiated to the recording medium, and a light source for irradiating light onto an optical recording medium to be inspected; A projection light adjusting means for adjusting the optical characteristics of the transmitted light or reflected light from the recording medium, an image inputting means for taking in the light from the projection light adjusting means as image information, and calculating the taken in image information for each predetermined section. An optical recording medium inspection apparatus is provided with an image processing means for processing and inspecting the presence or absence of defects in the recording medium.

Here, as the inspection light adjusting means, an optical element that can adjust the diffusion state of light from the light source, an optical element that can adjust the polarization state such as linearly polarized light, circularly polarized light, or elliptically polarized light can be used, or these can be used as appropriate. Combinations etc. can be adopted.

Further, as the projection light adjusting means, an optical element or the like that separates a specific polarization component or a specific band of light from the inspection object can be used, and it is desirable to set the projection light adjusting means appropriately in accordance with the inspection light adjusting means.

Further, these inspection light adjustment means and projection light adjustment means may be constructed by housing one or more optical elements in a prescribed package or the like, and which can be replaced as appropriate.

On the other hand, the image processing means processes the captured image information, measures and stores predetermined optical characteristics for each pixel, and then processes the image information as appropriate, such as one pixel in the image or a set of arbitrary pixels. It is possible to adopt a method in which the determination process is performed for each set predetermined section, and the section to be determined is sequentially moved to inspect the entire inspection object.

In addition, as a specific judgment process for each section, the average of all pixels in the section is calculated, the individual values of each pixel in the section are sequentially compared with the average value, and if the value is not within the allowable range, the inspection target is determined. It is possible to adopt a means for determining that there is an optically unique part in the part corresponding to the pixel with respect to the surroundings.

[Effect]

In the present invention, the optical recording medium to be inspected is irradiated with light from a light source, and the irradiated light is transmitted through the recording medium or reflected on the surface. This transmitted light or reflected light is changed according to the optical characteristics of each part of the recording medium, and is taken in from the image input means and the optical characteristics are determined by the image processing means.

At this time, the light irradiated onto the recording medium from the light source is converted by the inspection light adjusting means into light with an optimal diffusion state and polarization state depending on the inspection content. In addition, the light from the recording medium is
The projection light adjustment means separates the light into only specific polarization components and band components depending on the inspection content. Therefore, the image captured from the image input means accurately reflects the state of each part of the recording medium with respect to the specific characteristic to be inspected, and the influence of other characteristics is suppressed.

On the other hand, the image processing means performs arithmetic processing on the captured image information section by section, thereby accurately inspecting the entire recording medium. For example, by sequentially comparing each pixel with the average of all pixels within a predetermined section and detecting optically unique parts within the section, continuity within each section can be recognized, and each section can be inspected. By sequentially performing these steps, the continuity of the optical characteristics of the entire recording medium can be accurately determined.

Additionally, if a defect is discovered during the sequential inspection of each section, an interrupt process is performed, the defect inspection of the recording medium is finished at that point, and the subsequent inspection process is omitted and the next recording medium is inspected. It is possible to move on to inspection, and for this reason,
The overall working time for defect inspection work is shortened and processing efficiency is improved.

Therefore, in the present invention, the inspection light adjusting means and the projection light adjusting means can efficiently perform accurate inspections on various optical characteristics, and the image processing device can inspect each section to improve the accuracy of the inspection. and processing efficiency is further improved, thereby achieving the above objectives.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a defect inspection system l for optical recording media based on the present invention. Here, the defect inspection system 1 inspects polarization defects in an optical disk substrate 2 to be inspected.

The optical disk substrate 2 is a polycarbonate disk before being deposited with an information recording film for optical recording, and is held horizontally by a holding device 10. This holding device 1
0 is equipped with a spindle 11 that is engaged with the center of the optical disk substrate 2, and a drive section 12 that includes a motor that rotationally drives this spindle 11, and is capable of holding the substrate 2 and rotating it by an appropriate angle, 90 from the reference position by external command
It can be stopped at four angular positions: 180 degrees, 180 degrees, and 270 degrees.

A light source 13 is arranged below the optical disc substrate 2 to irradiate the substrate 2 with inspection light.

Further, above the optical disk substrate 2, a CCD camera 14 is arranged as an image input means for capturing the projection light transmitted through the substrate 2 as an image.

Cono CCD camera 14cm, for example 11000 x horizontal 1o
COD (Charge Co
This is a solid-state close-up camera using an upgraded device, which generates a signal according to the amount of incident light for each cell, and can output it as image information with each cell as one pixel.

The optical system from the light source 13 to the CCD camera 14 is arranged to cover about 174 parts of the optical disc substrate 2, and the optical disc substrate 2 is sequentially rotated by 1/4 rotation (90 degrees) by the holding means 10. Image information of the entire optical disk substrate 2 is captured by rotating the optical disk substrate 2 and sequentially photographing four images 1 to 3 as shown in FIG. Note that the pixels Px shown in FIG. 2 are shown schematically, and in reality, there are quite a large number of pixels Px.

An inspection light adjusting means 20 is arranged between the light source 13 and the optical disc substrate 2. Further, a projection light adjusting means 30 is arranged between the CCD camera 14 and the optical disk substrate 2.

The inspection light adjusting means 20 includes a double convex lens 2L 22 that appropriately diffuses the light from the light source 13, a polarizing plate 23 that allows only a specific polarized component to pass through, and a 174 that converts the polarized light of the passed specific component into circularly polarized light. It is provided with a wavelength plate 24 and adjusts the inspection light irradiated onto the optical disk substrate 2.

The projection light adjustment means 30 includes a 174 wavelength plate 31 that reconverts the circularly polarized light of the inspection light transmitted through the optical disc substrate 2 into linearly polarized light.
and a polarizing plate 32 that allows only specific polarized light components to pass through, and adjusts the projection light photographed by the CCD camera 14.

These inspection light adjustment means 20 and projection light adjustment means 30
are removably held by a substantially U-shaped frame 15 arranged to sandwich the optical disc substrate 2.

On the other hand, the CCD camera 14 is connected to an image processing means 40 that performs defect inspection processing based on the present invention. This image processing means 40 includes a converter 41 for reading image information from the CCD camera 14 and an image information memory 42.
It is equipped with

Of the image information sent from the CCD camera 14, the converter 41 sequentially scans each pixel Px within a pre-specified effective area A in the horizontal direction, and converts the signal into 8-bit 25-bit signals for each pixel Px.
It is converted into five-level brightness information Br and output to the image information memory 42. Here, as the effective area A, a fan-shaped area shown in FIG. 2 is set according to the type, size, etc. so that the recording surface of the optical disk substrate 2 is covered.

The image information memory 42 stores brightness information Br from the converter 41.
is stored together with the position information ^d of the pixel Px, and as shown in Fig. 3, it has four banks corresponding to images I to ■, respectively, and the luminance information for each image 1 to ■ is stored sequentially. By storing the information, the brightness information for the entire optical disc substrate 2 can be stored.

The image processing means 40 also includes a section setting means 43 for inspecting defects based on the image information stored in the image information memory 42, an average value calculation means 44, and a comparison determination means 4.
5, and further includes a control means 46 for controlling the overall operation.

The section setting means 43 sequentially sets the sections Sn based on the section information S given from the control means 46, and sequentially reads out the luminance information Br of each pixel Px corresponding to the section Sn from the image information memory 42. For example, if the partition information S is 2×
When a rectangular area with horizontal width 2 is specified, the partition setting means 43 selects the image information from the memory 42 as a partition S indicated by diagonal lines in FIG.
Pixels Pxs+ to PXS4 are designated as n, and each brightness information Brs+xBrs< is read out. Also, section Sn
After the processing is completed, the process moves to the section S6.1 indicated by the chain line, and four pixels Pxs+ to PXS4 are sequentially read out.

The average value calculation means 44 calculates the average value Br5m of the brightness information Brs, to Br5a read out by the section setting means 43.

The comparison/judgment means 45 sequentially calculates the brightness information Brs+ to Br54 read out by the section setting means 43 to the average value calculation means 4.
Average from 4 (compared with iBram, each brightness information Brs
are each given a predetermined tolerance range E for the average value BraIl.
If it is within the range, it is determined that the section Sn is not larger than that. on the other hand,
If there is brightness information Br-5i outside the variation range, it is determined that the corresponding pixel Pxs i is a non-uniform and unique part within the section SrI, and each determination result Re is returned to the control means 46.

The control means 46 monitors the determination result Re while the section setting means 43 sequentially processes each section Sn, and when a peculiar part is detected, omits the processing for each section Sn at that point. It is configured as follows.

Furthermore, the image processing means 40 is connected to an operation terminal device 50 using a normal personal computer or the like, which commands the operation of the entire defect inspection system 1 and the input/output of the image processing means 40 (effective area A, partitions, etc.). Setting of information S, tolerance range E, display of determination result Re), etc. are performed all at once by this terminal device 50. Further, the terminal device 50 is also connected to the holding device 10, and is configured to operate the holding device 10 in accordance with the photographing of images 1 to 2 by the image processing means 40, and rotate the optical disc substrate 2 to a predetermined position. ing.

In this embodiment configured as described above, the optical disc substrate 2 is inspected for defects in the following procedure.

During the inspection, the effective area A is set in advance from the terminal device 5o according to the type and dimensions of the optical disc substrate 2 to be inspected, and the section information S that is the processing unit is set, and the information is sent to the holding device 1o. The optical disk substrates 2 are sequentially set and the defect inspection system 1 is activated.

The activated defect inspection system 1 first starts with the CCD camera 1.
Image I is photographed by step 4. That is, the optical disk substrate 2 is irradiated with light from the light source 13, and the light transmitted through the substrate 2 is imaged by the CCD camera 14 to capture the image I. The captured image I is read into the image processing means 40, converted into luminance information Br by the converter 41 for each pixel Px, and stored in the image information memory 42.

Here, the light irradiated from the light a13 to the substrate 2 is converted by the inspection light adjustment means 20 into light in the optimal diffusion state and polarization state according to the inspection content, and the light from the substrate 2 is The light adjusting means 30 separates the light into only specific polarized components depending on the inspection content. Therefore, the image I captured by the CCD camera 14 accurately reflects the state of the substrate 2 with respect to the specific characteristic to be inspected, and the influence of other characteristics is suppressed.

Subsequently, the optical disk substrate 2 is rotated 90 degrees by the holding device 10, and the images ■ to ■ are sequentially projected in the same manner as the image ■ and stored in the image information memo IJ 42, for a total of four times. By storing, brightness information Br corresponding to the entire optical disc substrate 2 is stored in the image information memory 42.

After the entire image information of the optical disk substrate 2 has been captured, the defect inspection system 1 activates the image processing means 40, and uses the section setting means 43, the average value calculation means 44, and the comparison determination means 45 to read the image information in the image information memory 42. Brightness information Br
Processing and determination of a unique portion are performed for each section Sn selected from the above.

That is, the optical characteristics of the optical disc substrate 2 tested are as follows:
If the entire area is uniform or continuous even if there is variation, the determination result Re for each section Sn will always be normal, but if there is a locally peculiar part, the brightness information Bri of the pixel Pxi corresponding to that part will be , changes significantly with respect to the average value Br5m in the same section and deviates from the allowable range E based on the average value Br5m, the determination result Re becomes abnormal.

Therefore, it is determined that the inspected substrate 2 has an optically discontinuous defective portion, and a display to that effect is displayed on the terminal device 50.

Note that if a defective portion is found, it is clear that the optical disc substrate 2 is not suitable for use, and the control means 46
interrupts the subsequent processing and displays a request to set the next optical disk group Irl12.

According to this embodiment, the following effects can be obtained.

In other words, the optical characteristics of the optical disk substrate 2 to be inspected can be captured as image information, and defects can be automatically determined through image processing. Efficiency can be dramatically increased compared to conventional visual inspection.

Furthermore, when capturing image information, the inspection light adjustment means 20 can adjust the light irradiated onto the substrate 2 to have the optimum characteristics for inspection, and the projection light adjustment means 30 can adjust the characteristics of the light to be taken in as an image. , desired optical characteristics such as polarization defects can be accurately inspected.

Furthermore, inspection light adjustment means 20 and projection light adjustment means 30
By appropriately selecting , it is possible to easily handle a wide variety of inspections of various optical characteristics. In particular, in this embodiment, each means 20 and 30 is of a so-called cassette type, which improves work efficiency during preparation. This can be further improved.

On the other hand, when automatically determining defects by image processing, the image processing device 40 processes each section once, detects unique parts within each section, and confirms the continuity of each section. It is possible to detect a unique portion of optical characteristics regardless of the uniformity of the optical characteristics, and to determine the overall continuity of 61 LU, thereby making it possible to accurately determine a defective optical disk substrate 2.

In addition, since the image information to be inspected is quantitatively processed within the image processing device 40, it is possible to make an objective determination, and display the brightness information Br, the status of each section Sn, etc. on the terminal device 50 as appropriate. It is also possible to use it flexibly in inspections.

Furthermore, the section Sn to be processed can be set to any size and arrangement according to the section information S, for example, the section Sn
The overall uniformity can also be evaluated by increasing the number of pixels Px included in the image. At this time, the sensitivity to be judged can be adjusted by setting the tolerance range E, and by setting it according to the type of defect to be detected, it can be widely used for inspection of various defects. .

In addition, if a defect is discovered during the sequential inspection of each section, an interrupt process is performed, and the defect inspection of the recording medium is finished at that point, and the subsequent inspection process is omitted and the next recording medium is inspected. Since the process is shifted to inspection, it is possible to shorten the working time of the entire inspection work and further improve processing efficiency.

Furthermore, since the reading of the photographed image is limited to the effective area A according to the type and dimensions of the optical disc base vi2, processing for the meaningless area outside is omitted, and processing data related to calculation and judgment is The amount can be suppressed in advance, the processing time can be further shortened, and erroneous judgments due to noise etc. in the outside part of the effective area A can be avoided beforehand, and accurate inspection can be performed more reliably. Can be done.

Therefore, according to the defect inspection system 1 of this embodiment, subtle defects can be reliably detected, efficient high-speed processing can be performed, and it can be easily used for defect inspection in a line that mass-produces optical disk substrates 2. This makes it possible to check for defective products before they occur and reliably improve the quality of the product.

Note that the present invention is not limited to the above-mentioned embodiments, but also includes the following modifications.

In other words, 1/4 of the optical disk board 2 to be inspected is divided into images (most shadow), and these are configured to cover the entire area, but when the inspection target is small, the entire image may be combined. The image may be taken as a whole, or if it is large, it may be further subdivided.

In addition, the optical disk board 2 is used for sequential shooting of images 1 to ■.
Although the holding means 10 holding the optical disc 2 is configured to be rotated, it may be configured such that the optical disk substrate 2 is fixed and the optical system from the light source 13 to the COD camera 14 is moved.

Further, when the optical disk substrate 2 is large and the inspection image is divided also in the radial direction of the substrate 2, for example, the holding means 1
0 may be provided with a mechanism for moving the substrate 2 in parallel while keeping it horizontal.

Further, the control of the holding device i10 performed by the terminal device 50 may be replaced by the control means 46 of the image processing means 40,
Alternatively, the function of the control means 46 may be performed by an externally connected terminal device 50.

In addition, the image capture is not limited to the COD camera 14, and other image input means may be used.In short, this image input means can capture an image and produce an output that allows each processing as in the above embodiments to be performed. It is fine as long as it can be done.

Furthermore, when capturing images, the optical disc substrate 2
The transmission characteristics of the substrate 2 were inspected by passing light through the substrate 2. However, when inspecting the reflection characteristics of the surface, the light source 13, CCD camera 14, etc. are placed on the same side with respect to the surface to be inspected of the optical disk substrate 2, and the surface All you have to do is capture the reflected light from the camera as an inspection image.

Furthermore, in the above embodiment, in order to inspect the optical disc substrate 2 for polarization defects, a polarizing plate 23 and a high-frequency wave plate 24 are interposed between the substrate 2 and the light beam 13, and the substrate 2 and the CCD A 174 wavelength plate 31 and a polarizing plate 32 were interposed between the camera 14 and the substrate 2 was irradiated with circularly polarized light, but this may be changed depending on the defect to be inspected. Polarizing plate 23, 32 and 1/4 wavelength plate 2
4.31 may be omitted.

On the other hand, in the embodiment described above, the pixels Px of the image processed by the image processing means 40 are arranged in a vertical and horizontal grid pattern.
This may be divided along the circumferential direction of the optical disc substrate 2.

In addition, the section S is not limited to the setting of two pixels each in the vertical and horizontal directions as in the above embodiment, but may be set as a large area if overall uniformity is required, or in the case of the optical disk substrate 2, a large area may be set. In order to record and play continuously in the direction,
It is also possible to set a circumferentially long region as a section and determine the continuity of its optical characteristics.

Furthermore, as for the effective 6J [area A, for example, in the case of a disk-shaped inspection target such as the optical disk substrate 2, if the above-mentioned means for determining the fan-shaped area by specifying the effective outer diameter and the effective inner diameter, etc. is adopted. If the object to be inspected has a different shape, it is sufficient to register each projection form.

In addition, in limiting the area to the valid area, by taking advantage of the fact that the brightness of the part to be inspected and the brightness of the part outside the area change drastically, each pixel is determined to be valid or invalid when converting the brightness information Br in the converter 41. It is also possible to perform a process such as determining only valid ones and storing them in the image recording memo IJ42.

Furthermore, the image processing means 40 that performs image processing is not limited to the method and configuration of the above embodiment, but in short, the image processing means 40 inspects the distribution of optical characteristics of the optical disk substrate 2 captured as image information by appropriate image processing, and detects abnormalities. Any method may be used as long as it can determine defective elements such as non-uniformity in parts and characteristics.

In the above embodiment, the optical disk substrate 2 was used as the optical recording medium to be inspected, but it may also be applied to other optical recording media such as an optical disk on which a recording layer is formed as a finished product or a magneto-optical disk. The optical recording medium inspection apparatus of the present invention can be widely used for optical inspection of recording media that requires high precision. In particular, the present invention is effective for inspecting optical disk substrates using i3 light.

(Effects of the Invention) As explained above, according to the optical recording medium inspection apparatus of the present invention, defects in the recording medium to be inspected can be efficiently inspected, and even subtle defects can be reliably detected. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the overall configuration of an embodiment of the present invention, FIG. 2 is a schematic diagram showing the state of the inspection object and the inspection image in the embodiment, and FIG. 3 is the storage of image information in the embodiment. A conceptual diagram showing the state, FIG. 4 is a conceptual diagram showing processing for each section in the embodiment. 1... Defect inspection system which is an inspection device, 2... Optical disk substrate which is an optical recording medium, 13... Light source,
14... CCD camera, which is a manual image means, 20...
- Inspection light adjustment means, 21.22... convex lens, 23.
32...Polarizing plate, 24, 31...174 wavelength plate, 3
0... Projection light adjustment means, 40... Image processing means, A
...Effective area, B"...Brightness information, Brs xBr
sa...brightness information of pixels within the section, Br5m...average value of brightness information within the section, E...allowance, range, Px.
... Pixel, Pxs 1 to PXS4 ... Pixel in section,
Re: Judgment result, S: Section information, Sn: Section to be inspected.

Claims (2)

[Claims] (1) A light source that irradiates light to an optical recording medium to be inspected, an inspection light adjustment means that adjusts the optical characteristics of the light irradiated to the recording medium, and a light source that irradiates light to the optical recording medium to be inspected; a projection light adjustment means for adjusting optical characteristics; an image input means for taking in the light from the projection light adjustment means as image information; and arithmetic processing of the taken-in image information for each predetermined section to determine the presence or absence of defects in the recording medium. 1. An optical recording medium inspection apparatus comprising: an image processing means for inspecting an optical recording medium. (2) The optical recording medium inspection apparatus according to claim 1, wherein the optical recording medium is an optical disk substrate.