JPH08249658A - Common inspecting apparatus for optical disk - Google Patents

Abstract

PURPOSE: To inspect three kinds of disks, that is, a mother board, a stamper and an optical disk by one inspecting apparatus. CONSTITUTION: The apparatus is provided with a loading/rotating mechanism 4' which can load disks for every kind, an optical head 5' used in common, a servo control part 6' having two sets of amplifiers 61', 62' each consisting of three switchable amplifiers to which a focus control signal SFR and a tracking control signal STR outputted from the optical head 5' are inputted, a pre-format inspection part 7' having two sets of amplifiers 71', 72' each consisting of three amplifiers to which polarization signals SA, SB are inputted, a medium inspection part 8, a modulation degree inspection part 9 and a data-processing part 10. When a mother board 1 and a stamper 2 are to be inspected, a correction glass 56 for focusing a spot SP is inserted in the optical head 5'. Moreover, a current control circuit 5b is arranged in the optical head 5' to set the intensity of the spot SP properly for every kind of disks.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc common inspection apparatus capable of inspecting an optical disc and three types of discs, a mother master and a stamper for duplicating the optical disc, by a single device.

[0002]

2. Description of the Related Art There are various types of optical disks, all of which have a huge recording density as compared with magnetic disks.
Since data can be accessed in a non-contact manner, there are advantages such as excellent data storability, and rewritable optical disks are used as storage devices for computer systems and the like. The outline of the optical disk manufacturing process will be described with reference to FIG. (a) shows a mother master 1, the mother master 1 a photoresist H _R is applied to the surface of suitable diameter phi ₀ glass disk G of laser cutting to this, the development, by performing a vapor deposition process, a spiral guide The track T _R is pierced. Each guide track T _R is divided into a plurality of n sectors S _{0 to} S _n in the circumferential direction, and an ID portion is provided in each sector to provide a pit p _{T for} a synchronization code or an identification code.
Is pierced. Next, when depositing a thin film of nickel Ni to the surface of the mother stamper 1, the track T _R and each pit p _T transcribed as T _R ', p _T' inverted, and peeling the thin film, ( The stamper 2 shown in b) is created, and the center hole 2a is provided in the center thereof. Then, stamper 2
On the other hand, with an injection molding machine, for example, a substrate of polycarbonate PC is pressed, T _R 'and p _T ' are inverted again and transferred as T _R "and p _T ", and a recording film R is formed on the surface. An optical disk 3 shown in (c) is reproduced by coating a reflective film of aluminum. Further, since it is used on both sides, as shown in (d), the two optical disks 3A and 3B may be bonded together to form an optical disk 3 '. These optical disc 3 and optical disc 3 '
Is protected by covering a cover glass (not shown).

FIG. 4 shows sectors S _{0 to} S _{n in} which one track of each track T _R is divided into a plurality of sectors, and each sector is provided with an ID section and a data area. Expanding the ID portion, the sector mark SM, SYNC1 for synchronization, there is the pit p _T for ID for identification, such as a track number and sector number, since they are previously穿溝the mother master 1, preformat Is called. Further, in each data area, the SYNC3 for synchronization and each pit p _D of the recording data are written at the time of use, and the recorded data is reproduced by the clock pulse synchronized with the SYNC3. In the case of the rewritable type, the data pit p _D already recorded is erased or overwritten to update the data.

The track T _R , the pits p _T of each preformat, and the medium in the data area must be free from defects such as scratches and adhered foreign matters. Optical disc inspection apparatus has been developed as a prior art. However, this inspection device is used as a dedicated device for each of the mother master 1, the stamper 2, and the optical disc 3 (or the optical disc 3 ').

FIG. 5 shows the basic structure of each dedicated inspection apparatus according to the above-mentioned prior art. Each dedicated inspection device includes a mounting rotation mechanism 4, an optical head 5, a servo control unit 6, a preformat inspection unit 7, a medium inspection unit 8, a modulation degree inspection unit 9, and a data processing unit 10. Hereinafter, the optical disc 3 will be described as a representative. The optical disk 3 is chucked by the chuck head 41 of the mounting rotation mechanism 4 and the motor (M) 42
To rotate. On the other hand, the optical head 5 seeks in the radius R direction of the optical disc 3 by the carriage mechanism 5a.

FIG. 6 shows a schematic structure of the optical head 5 (an example of an MO head). The MO head 5 is of a magneto-optical type and is more suitable for defect detection than a write-once type used in a drive device for an optical disc. Although the MO head is known, the outline of its operation will be described. M
In the O head, the linearly polarized laser beam from the laser light source 51 is collimated by the collimating lens (CL), passes through the polarizing beam splitter (PBS ₁ ), passes through the mirror (M _R ) and is spotted by the objective lens 52. S
_It is focused on _P and irradiated onto the optical disc 3. in this case,
The plane of polarization of the spot S _P is a groove direction of the track T _R. The reflected light of the spot S _P due to the groove of the track T _R or each pit P _T of the preformat is condensed by the objective lens 52, reflected by M _R and PBS _1, and split by the beam splitter (HM ₁ ). One of them is λ
The polarized light is split by the PBS ₂ through the / 2 plate, and each is imaged by the imaging lens (KL) on the photodetectors 53 and 54 of the pin photodiode, and polarized signals S _A and S _B polarized in the directions perpendicular to each other are formed. Is output. The other divided by HM ₁ is re-divided by HM ₂ , and one is converged into an elliptical shape by a cylindrical lens (SL) and enters a four-divided photodetector 53, which outputs a focus control signal S _FR. It In addition, the other sub-divided beam enters the four-divided photodetector 54 through M _R , and the tracking control signal S
_TR is output.

FIG. 7 shows a schematic configuration of the servo control unit 6, the preformat inspection unit 7, the medium inspection unit 8 and the modulation degree inspection unit 9. The outline of these operations will be described below. In the servo control unit 6, the focus control signal S
_{The FR} and the tracking control signal S _TR are level-adjusted by the fixed gain amplifiers 61 and 62, smoothed by the low-pass filter (LF), and given to the optical head 5 by the drive amplifier (DRIV) for auto-focusing. Tracking control is performed. In the pre-format inspection unit 7, the polarization signals S _A and S _B are level-adjusted by the fixed gain amplifiers 71 and 72, and the adders are added.
The difference signal S _AD input to 81 and output _therefrom is automatically adjusted to a constant level by the AGC amplifier 74, the preformat is reproduced by the data reproduction circuit 75, and the reproduction data is input to the comparison / determination unit 76 and written. If the two are different from each other, the preformat is determined to be defective. Also in the medium inspection unit 8,
The output signals of the above-mentioned amplifiers 71 and 72 are input to the adder 81, and the sum signal S _AD output from this is the + of the comparators 82 and 83.
It is input to the terminal and the-terminal and compared with the threshold voltages L ₁ and L ₂ provided from the threshold generation circuit 84, respectively. Each dark defect is detected. In the modulation degree inspection unit 9, the above-mentioned sum signal S _AD , the error signal of the servo system, etc. (outputs of the amplifiers 61 and 62) are input to the multiplexer 7.
3 is selected by this, digitized by the A / D converter 91, the peak value and the like are detected by the peak value detection circuit 92, and these peak values are compared and calculated with various modulation degree standard values. To be judged. As a result, the depth of the groove of the track T _R or the pit p _T of the preformat,
Inspected for abnormal width or shape. The above-mentioned preformat, each defect data of the medium, and the data of the modulation degree are stored in the microprocessor (MP) of the data processing unit 10.
U) 101, and edit it appropriately to the printer (P
RNT) 103. The memory (MEM) 102
The above-mentioned preformatted original data is stored in.

FIG. 8 exemplifies the above-mentioned medium defect. When the reflectance of the medium in the preformatted area is large, a pulse having a large peak value and a large width generally exists in the reproduced signal, and the reflectance is large. Since the signal waveform disappears when is small, these are compared with the thresholds L ₁ and L ₂ , and the bright defect E,
Each is detected as a dark defect M. In the data area,
For the same reason, the bright defect E and the dark defect M have the threshold values L ₁ and L 2.
Detected by ₂ respectively. The defect data preformat and data regions detected by the above, it is processed by the data processing unit 9, and the defect type, is added the number of the track groove T _R and the sector S in the presence of a defect, the printer (PRNT) Printed by 93.

Next, a dedicated inspection device for the mother master 1 and the stamper 2 will be described. Here, comparing the media of the three types of disks to be inspected, the mother master 1 is glass G
And nickel film H _R , and the stamper 2 is nickel Ni
And in itself, the optical disk 3, the reflection film of Aruminiumu Al on the recording film R is coated, these reflectance have much different, for example H _R, Ni is 70
80% and Al is 15 to 35%, so that the reflection intensity of the mother master 1 and the stamper 2 is much higher than that of the optical disc 3. Therefore, the amplifiers 61, 62 of the servo control unit 6
Then, the amplifiers 71 and 72 of the pre-format inspection unit 7 may be saturated, resulting in malfunction. If the amplifier 61.62 is saturated, autofocus and tracking control are not stable. When the amplifiers 71 and 72 are saturated, the adder 81 and A
The GC amplifier 74 does not work well and interferes with preformat, medium and modulation test. Intensity of each inspection apparatus dedicated for different reflectivity of the disk, by adjusting the supply current of the laser light source 51, the reflected light by irradiating a spot S _P output appropriate intensity for each disk with respect to more And each amplifier 61, 62, 71, 72 having a proper operating range without being saturated with respect to each disk is used to stably detect each defect.
Next, the difference between the dedicated inspection devices other than the above will be described. As described above, the stamper 2 and the optical disc 3 have the center hole 2
Although there are a and 3a, the mother master 1 does not have this, so that the mounting rotation mechanism 4 of each dedicated inspection device has a structure corresponding to the presence or absence of the central hole. Also, the optical disc 3
Although there is a cover glass, the mother master 1 and stamper 2
I don't have this. Spot S _P focused to the optical disc 3 to this itself would not in focus with respect to the mother master 1 and the stamper 2, the mother master 1 and the stamper 2
In a dedicated inspection apparatus, between the objective lens 52 and the disk of the optical head 5, the spot S _P is focused by inserting a correction glass corresponding to the cover glass.

[0010]

The dedicated inspection device for each of the above three types of disks has a problem. First, although there are many optical disks 3 and 3 ', the number of mother masters 1 and stampers 2 is far less than that of the optical disks 3 and 3', so that a dedicated inspection apparatus for them has a low operating rate and is inefficient.
Therefore, by inspecting three kinds of disks in common by one inspection device, it is desirable to eliminate a dedicated device having a low operating rate, thereby improving cost performance. Next, there is a problem of preformatted reproduction data of the mother master 1 and the stamper 2. For the optical discs 3 and 3 ', the reproduction data of the pre-formatted pit p _T is
Quality standards are specified. On the other hand, the mother master 1 and the stamper 2 track groove T depths of _R and the pit p _T (or height), width, shape is different from those of the optical disk 3, which is now transferred, therefore, the mother master 1 and the stamper The waveform of the reproduced signal 2 is naturally different from that of the optical disc 3. Nevertheless, since no quality standard is specified for the reproduction data (or signal waveform) of the mother master 1 and the stamper 2, these reproduction data are
It is collated with the original data without knowing whether it is right or wrong. In order to know whether these reproduced data are correct or not, the same optical head 5 reads out and reproduces the preformats of three types of discs, compares the reproduced data of the three parties, and examines the mutual correlation. Is considered effective, that is, it is necessary to inspect three types of disks with one device. The present invention has been made in view of the above,
It is an object of the present invention to provide a common inspection apparatus capable of inspecting each defect of three types of disks, that is, a mother master 1 and a stamper 2 and optical disks 3 and 3'by one inspection apparatus.

[0011]

SUMMARY OF THE INVENTION The present invention is a common optical disk inspection apparatus, which mounts and rotates each of the above-mentioned three kinds of disks by type, and irradiates each disk with a laser spot. Then, the optical head for reading the data, the servo control unit for performing the auto focus and tracking control of the optical head, the preformats read and reproduced by the optical head are compared with the original data, and the defect is inspected. A pre-format inspecting unit, a medium inspecting unit for inspecting optical defects of the medium in the pre-format and recording data area, and a modulation degree inspecting unit for inspecting the quality of the signal modulation degree of the track groove and pre-format pits are provided. Moreover, the laser spot is focused on each of the three types of discs by inserting or removing the correction glass. Focusing means, switching means for switching the intensity of the laser spot to an appropriate value for the difference in reflectance depending on the type of each disc, and servo control for the difference in signal modulation degree between the track groove and the preformatted pit. And a switching means for switching the gains of the amplifiers of the pre-format inspection section and the modulation degree inspection section to appropriate values, respectively, and enable each of the above-mentioned inspections of three types of disks by the same device. is there.

[0012]

In the above-mentioned common inspection apparatus, each of the three types of discs is mounted and rotated by a mounting rotation mechanism for each type, the optical head is commonly used for each disc, and the laser spot from the laser light source is used. The appropriate intensity is set by the switching means, and each disc is focused and irradiated by the focusing means. Further, with respect to the difference in signal modulation degree between the track groove and the preformat pit, the gains of the amplifiers of the servo control section, the preformat inspection section and the modulation degree inspection section are set to appropriate values by the switching means. With the appropriate spot intensity of each amplifier, each amplifier operates stably without being saturated, and the servo control section performs good auto focus and tracking control for the optical head, and the pre-format inspection section, medium inspection section and modulation section. In the degree inspection section, the subtractor and the adder operate stably, and the correct difference signal and sum signal are obtained,
Defects or defects in pre-format, media and modulation depth are inspected as well as dedicated inspection equipment.

[0013]

1 and 2 show an embodiment of a common inspection apparatus according to the present invention. FIG. 1 is a block diagram of a mounting / rotating mechanism 4'of the common inspection apparatus, and FIG. 2 is an optical head of the common inspection apparatus. 5 ', servo control unit 6', pre-format inspection unit 7 '
The partial view of is shown. Note that this ['] indicates that each part in FIGS. 6 and 7 has been changed in the present invention, and the other constituent elements are the same as those in FIGS. 6 and 7 and are denoted by the same reference numerals. In FIG. 1, (a) shows a mounting / rotating mechanism 4 ′ for the mother master 1. A disc 44 such as an aluminum is screwed and fixed to a rotary shaft 43 of a drive motor M42, and a porous ceramic suction plate is mounted on the upper surface thereof. 45 is attached, and the mother master 1 placed on this is sucked and held by the air suction device 46. (b) is for the stamper 2, which is
Since it is necessary to position the center hole 2a, a positioning tool 47 having the illustrated shape is screwed into the center of the disk 44 for positioning with respect to the stamper 2 placed on the suction plate 45, and the air suction device 46 also causes the positioning. Aspirate and hold. (c) is for the optical discs 3, 3 '. In this case, the same chuck head 41 as in FIG.
Screw to and chuck the disc to it.

In FIG. 2A, an optical head 5'adds a current control circuit 5b to the optical head 5 of FIG.
This is connected to the MPU 101 of the data processing unit 9. Also,
Objective lens for inspection of mother master 1 and stamper 2
Between 53 and the disk, insert the correction glass 57 corresponding to the cover glass of the optical disk 1, to focus the spot S _P. It should be noted that the supply current values for the three types of disks having different reflectances and the thickness of the correction glass 57 are the same values as those of the dedicated inspection device, and each supply current value is stored in the MEM 102. In FIG. 2B, the servo control unit 6'provides two sets of amplifier groups 61 'and 62' instead of the amplifiers 61 and 62 of the servo control unit 6 of FIG. The amplifier group 61 'includes three amplifiers 611,612,613 having gains and operating ranges corresponding to three types of disks, and switches 614,615 for switching between them.
The same applies to the amplifier group 62 '. Further, the preformat inspection section 7'is provided with two sets of amplifier groups 71 'and 72' similar to the above, instead of the amplifiers 71 and 72 of the preformat inspection section 7 of FIG. It should be noted that the switching of the amplifiers of each set may be performed by a method of replacing the substrate without using switches.

A method of inspecting three types of disks in the above-described common inspection apparatus will be described below with reference to FIGS. 1 and 2 in combination with FIG. In the inspection, the mounting / rotating mechanism 4'corresponding to the type of the disc is replaced, and the disc is mounted and rotated. In the case of the optical disks 3 and 3 ', the correction glass 57 is not used. In the case of the mother master 1 and the stamper 2, after inserting the correction glass 57 into the optical head 5', the supply current value is set to ME.
The data is read from M102 and given to the current control circuit 5b, and each disk is irradiated with a laser spot S _P having an appropriate intensity. In addition, the amplifier of each amplifier group is switched to the one corresponding to the disc type. The focus control signal S _FR and the tracking control signal S _TR output by the optical head 5 ′
Is stably adjusted by each amplifier of the servo control unit 6 ′ without being saturated, so that the optical disc 3 is satisfactorily autofocused and tracking-controlled. On the other hand, the polarization signals S _A and S _B are adjusted in level stably without being saturated by each amplifier of the pre-format inspection unit 7 ′ and the subtractor
73 and the adder 81 to input more accurate difference signals S _SB
And the sum signal S _AD is output, and there is a defect in the preformat,
Bright and dark defects of the medium and defects of the modulation degree are inspected in the same manner as in each dedicated inspection device, and the defect or defective data is MPU10.
The data is sequentially captured by the printer 2, edited, and output to the printer 103.

[0016]

As described above, according to the common inspection apparatus of the present invention, three types of disks, that is, a mother master, a stamper, and an optical disk, are inspected by one inspection apparatus, so that the conventional mother master is used. Since no dedicated inspection device with low operating rate for the stamper is required, the cost is saved accordingly, and the preformats of the three types of discs are read and reproduced by the same optical head, and the reproduction data of the three types are mutually exchanged. By comparing and checking the correlation, it can be used to judge whether the reproduction data of the mother master and the stamper, which has not been standardized in the past, is correct, and the effect that contributes to the cost performance of optical disc inspection and the improvement of inspection technology. There is a big one.

[Brief description of drawings]

1A and 1B are configuration diagrams of a mounting / rotating mechanism according to an embodiment of the present invention, FIG. 1A is an explanatory diagram of a rotating mounting mechanism of a mother master, and FIG. 1B is a rotation of a stamper. It is an explanatory view of a mounting mechanism, and (c) is an explanatory view of a rotary mounting mechanism of an optical disc.

2A and 2B are partial views of a common inspection apparatus according to an embodiment of the present invention, FIG. 2A is an explanatory diagram of light beam irradiation in the case of inspection of a mother master and a stamper, and FIG. FIG. 4 is a block diagram of a servo control system and a preformat inspection unit that receive a signal from an optical head.

FIG. 3 is an explanatory diagram of an optical disc manufacturing process, (a) is an explanatory diagram of a mother master, (b) is an explanatory diagram of a stamper, and (c) is an explanatory diagram of an optical disc. is there.

FIG. 4 is an explanatory diagram of a plurality of sectors into which each track is divided.

FIG. 5 is a basic configuration diagram of a dedicated inspection device for an optical disc.

FIG. 6 is a schematic configuration diagram of an optical head.

FIG. 7 is a schematic configuration diagram of a servo control unit, a preformat inspection unit, a medium inspection unit, and a modulation degree inspection unit.

FIG. 8 is a waveform diagram showing an example of a bright defect and a dark defect of a medium in a preformat and a data area.

[Explanation of symbols]

1 ... Mother master, 2 ... Stamper, 3, 3 '... Optical disk, 2a, 3a ... Center hole, 4 ... Conventional mounting rotation mechanism, 41 ...
Chuck head, 42 ... Drive motor (M), 4 '... Mounting rotation mechanism of the present invention, 43 ... Rotation shaft, 44 ... Aluminum disc, 45 ... Adsorption plate, 46 ... Air suction machine, 47 ... Positioning tool, 5 ... Conventional optical head, 51 ... Laser light source, 52 ... Objective lens, 53, 54, 55, 56 ... Light receiver, 5a ... Carriage mechanism 5 '... Optical head in this invention, 57 ... Correction glass,
5b ... Current control circuit, 6 ... Conventional servo control section, 61, 62
... Amplifier, 6 '... Servo signal creation unit of this invention, 61', 6
2 '... amplifier group, 7 ... conventional preformat inspection section,
71,72 ... Amplifier, 73 ... Subtractor, 74 ... AGC amplifier, 75 ...
Data reproduction circuit, 76 ... Comparison determination unit, 7 '... Preformat inspection unit of this invention, 71', 72 '... Amplifier group, 8 ... Medium inspection unit, 81 ... Adder, 82, 83 ... Comparator, 84 ... Threshold value Generation circuit, 9 ... Modulation degree inspection section, 91 ... A / D converter, 92
... Crest value detection circuit, 93 ... Comparison determination section 10 ... Data processing section, 101 ... Microprocessor (MP
U), 101 ... Memory (MEM), 103 ... Printer (PR)
NT), T _R ... guide track, S ₀ ~S _n ... sector, p
_T, p _D ... Pit, S _P ... laser spot, PBS ... polarized beam splitter, HM ... half mirror M _R ... mirror, CL ... collimator lens, KL ... imaging lens, SL ... cylindrical lens, LF ... low pass filter, DRIV ... drive amplifier, S _FR ... focus control signal, S _TR ... tracking control signal, S _A , S _B ... polarization signal, S _SB ... difference signal, S _AD ... sum signal, L ₁ , L ₂ ... threshold value, E ... medium Bright defect of M, dark defect of medium.

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[Procedure amendment]

[Submission date] June 30, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

1A and 1B are configuration diagrams of a mounting / rotating mechanism according to an embodiment of the present invention, FIG. 1A is an explanatory diagram of a rotating mounting mechanism of a mother master, and FIG. 1B is a rotation of a stamper. It is an explanatory view of a mounting mechanism, and (c) is an explanatory view of a rotary mounting mechanism of an optical disc.

2A and 2B are partial views of a common inspection apparatus according to an embodiment of the present invention, FIG. 2A is an explanatory diagram of light beam irradiation in the case of inspection of a mother master and a stamper, and FIG. FIG. 4 is a block diagram of a servo control system and a preformat inspection unit that receive a signal from an optical head.

FIG. 3 is an explanatory diagram of an optical disc manufacturing process, (a) is an explanatory diagram of a mother master, (b) is an explanatory diagram of a stamper, and (c) is an explanatory diagram of an optical disc. (D)
[FIG. 3] is an explanatory diagram of a case where two optical disks are bonded together.

FIG. 4 is an explanatory diagram of a plurality of sectors into which each track is divided.

FIG. 5 is a basic configuration diagram of a dedicated inspection device for an optical disc.

FIG. 6 is a schematic configuration diagram of an optical head.

FIG. 7 is a schematic configuration diagram of a servo control unit, a preformat inspection unit, a medium inspection unit, and a modulation degree inspection unit.

FIG. 8 is a block diagram of an inspection apparatus for a mother master and a stamper.

FIG. 9 is a waveform diagram showing an example of a bright defect and a dark defect of a medium in a preformat and a data area.

[Explanation of Codes] 1 ... Mother master, 2 ... Stamper, 3, 3 '... Optical disc, 2a, 3a ... Center hole, 4 ... Conventional mounting rotation mechanism, 4
1 ... Chuck head, 42 ... Drive motor (M), 4 '...
The mounting rotating mechanism of the present invention, 43 ... Rotating shaft, 44 ... Aluminum disc, 45 ... Suction plate, 46 ... Air suction device,
47 ... Positioning tool, 5 ... Conventional optical head, 51 ... Laser light source, 52 ... Objective lens, 53, 54, 55, 56
... light receiver, 5a ... carriage mechanism 5 '... optical head in this invention, 57 ... correction glass, 5b ... current control circuit, 6 ... conventional servo control section, 6
1, 62 ... Amplifier, 6 '... Servo signal creating section of the present invention, 61', 62 '... Amplifier group, 7 ... Conventional preformat inspection section, 71, 72 ... Amplifier, 73 ... Subtractor, 7
4 ... AGC amplifier, 75 ... Data reproduction circuit, 76 ... Comparison determination section, 7 '... Preformat inspection section of this invention, 7
1 ', 72' ... Amplifier group, 8 ... Medium inspection unit, 81 ... Adder, 82, 83 ... Comparator, 84 ... Threshold generation circuit,
9 ... Modulation degree inspection unit, 91 ... A / D converter, 92 ... Crest value detection circuit, 93 ... Comparison determination unit 10 ... Data processing unit, 10
1 ... microprocessor (MPU), 101 ... memory (MEM), 103 ... printer (PRNT), T R _... guide _{track, S} o to S n _... sector, _{p T,} p D _... Pit, S P _... laser spot, PBS ... polarized beam splitter, HM ... half mirror M R _... mirror, CL ... collimator lens, KL ... imaging lens, SL ... cylindrical lens, LF ... low pass filter, DRIV ... drive amplifier, S _{FR ...} focus control _{signal, S TR} ... Tracking control signals, S _A , S
_B ... Polarization signal, _SSB ... Difference signal, _SAD ... Sum signal,
L ₁ , L ₂ ... Threshold value, E ... Medium bright defect, M ... Medium dark defect.

Claims (1)

[Claims] 1. A spiral track groove, and a plurality of sectors dividing the track groove in a circumferential direction are provided with a preformat including a sync code and ID data pits, and a recording data area. Three types of discs, mother master, stamper and optical disc, are inspected.
A mounting / rotating mechanism that mounts and rotates the three types of discs by type, an optical head that irradiates a laser spot on each of the discs to write / read data, and an autofocus and tracking control of the optical head. A servo control section for performing a pre-format inspection section for inspecting defects by comparing each pre-format read and reproduced by the optical head with the written original data, and the pre-format and the recording data area of the medium. A medium inspection section for inspecting optical defects, and a modulation degree inspection section for inspecting the quality of the signal modulation degree of the track grooves and preformatted pits, and correction glass for the three types of disks. Focusing means for focusing the laser spots by inserting or removing the laser spots, depending on the type of each disc. Switching means for switching the intensity of the laser spot to an appropriate value with respect to the difference in reflectance, and the servo control section and the preformat inspection section with respect to the difference in signal modulation degree between the track groove and the preformat pit, The gain of the amplifier of the modulation degree inspection unit,
Switching means for switching to an appropriate value, respectively, and is configured to perform the inspections for the three types of disks,
A common inspection device for optical disks, which can be performed by the same device.