JPH09180269A - Method and system for reproducing optical disk master disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To grasp a normal/defective condition of recording state in initial stage by covering an information recording surface with a refraction medium, placing a transparent substrate with a refractive index equivalent to a resin substrate of a replica disk on it and reproducing it with laser light of a specified wavelength. SOLUTION: The information recording surface 2 is covered by the refraction medium 4 of the refractive index n2, and the transparent substrate 7 of the refractive index n1 equivalent to the resin substrate of the replica disk is placed on it, and the signal groove part of the information recording surface 2 on an optical disk master disk 1 is read and reproduced by the laser light 8 of the wavelength λ2=(n2/n)×λ1. At this time, the wavelength λ1 is made the wavelength of the reproducing laser light of the replica disk. Since the laser light 8 of wavelength λ2 is converged on the signal groove part transmitted through the transparent substrate 7 and the refraction medium 4, the wavelength at the time becomes (1/n2)×((n2/n1)×λ1)=λ1/n1, and becomes equal to the wavelength of the time when the replica disk is reproduced. Thus, the normal/defective condition at the recording state of the initial stage of an optical disk manufacturing process is grasped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing method and system for inspecting an optical disk master used for manufacturing an optical disk.

[0002]

2. Description of the Related Art FIG. 3 is a schematic view showing a conventional optical disk manufacturing process. In FIG. 3, in order to manufacture an optical disc, first, a glass master 9 is created. The glass master 9 is coated with a photosensitizer (photoresist) 10 to form a photosensitizer 1
The signal from the master tape 11 is recorded on the glass master 9 coated with 0 with the laser beam 8. Then, by developing, the master master 12 is created.

A silver conductive film 13 is applied to the master master 12, nickel plating 14 is applied, and then the silver conductive film 13 is removed to form the stamper 3.
A normal optical disk (replica disk) 5 is completed by attaching the stamper 3 to a mold and molding a resin such as polycarbonate using the mold.

FIG. 4 is a schematic diagram showing a main part of the structure of a conventional optical disc reproducing system. In FIG. 4, when reproducing the replica disk 5, the laser beam 8 having the wavelength λ1 incident on the objective lens 16 reaches the information recording surface 2 through the resin substrate 6 having the refractive index n1. A reflection film 17 of ariminium is attached to the information recording surface 2, and a protection film 18 for protecting the reflection film 17 is further provided. Since the reproduction of the replica disk 5 is performed through the resin substrate 6, the objective lens 16 is designed in consideration of the thickness of the resin substrate 6 and the refractive index n1.

FIG. 5 is a schematic view showing a main part of a reproducing system of a conventional optical disc master. The optical disc master 1 is a stamper 3 for making a replica disc 5, and the surface on the signal reading side is not covered with a transparent substrate. As shown in FIG. 5, the optical disc master 1 used for making the above-mentioned replica disc 5 has the signal recording surface 2 not covered with the resin substrate 6, as shown in FIG.
Reproduction is performed using the reproduction pickup of the replica disk 5. When the reproduction of the replica disc 5 is performed by using the reproduction pickup, the transparent substrate 7 having the same optical thickness as the resin substrate 6 of the optical disc is arranged between the objective lens 16 and the information recording surface 2. When the objective lens 16 designed for reproducing the optical disc master 1 is used, the transparent substrate 7 is not necessary.

[0006]

The replica disc 5 and the optical disc are used regardless of whether the pickup for reproducing the replica disc 5 is used or the objective lens 16 designed for reproducing the optical disc master 1 is used. In the master disk 1, there is a difference whether or not the resin substrate 6 is provided in the signal groove portion 15, and therefore, the signals obtained at the time of reproduction are different.

FIG. 6 is a schematic view showing a main part in reproducing an optical disc. In general, signal reproduction on an optical disk utilizes the phase difference between the reflected light from the upper portion 19 of the information recording surface and the reflected light from the lower portion 20 of the information recording surface, as shown in FIG. In the replica disk 5, the resin substrate 6 having the refractive index n1 is arranged from the upper portion 19 of the information recording surface to the lower portion 2 of the signal recording surface.
Since it is between 0 and 0, the refractive index is n1 from the upper portion of the resin substrate 6 to the information recording surface bottom portion 20, and the information recording surface upper portion 19
At the boundary, the refractive index does not change, and the phase of the reflected light does not change.

However, when reproducing the optical disc master 1, as shown in FIG. 5, since there is no resin substrate 6 having a refractive index n1 in the replica disc 5 in the signal groove portion 15, refraction in the transparent substrate 7 and the signal groove portion 15 is caused. The rate changes, and the phase of the reflected light changes unlike the case of reproducing the replica disk 5. Assuming that the refractive index of the signal groove portion 15 is n2 and the wavelength of the incident light is λ1, the phase of the reflected light at the signal groove portion 15 is λ1 / n2, and the larger the refractive index n2, the more the phase difference between the incident light and the reflected light. Increase.

That is, in the replica disk 5, as shown in FIG. 4, the information recording surface bottom 20 is formed from the upper portion of the resin substrate 6.
Up to the same refractive index, so the refractive index does not change,
In the optical disc master 1, as shown in FIG.
Since the refractive index of the space up to the bottom portion 20 of the information recording surface is different from that of the replica disc 5, the phase of the reproduction signal of the signal groove portion 15 is different between the reproduction of the replica disc 5 and the reproduction of the optical disc master 1 and the optical disc master 1 In, the reflected light corresponding to the signal groove portion 15 of the replica disk 5 cannot be obtained.

Therefore, even if the signal is observed at the stage of the optical disc master 1, it is difficult to confirm the recording state of the recording signal on the optical disc master 1 because it is different from the reproduction condition on the replica disc 5, and it is accurate. In order to check the proper recording state, the replica disk 5 had to be created, and the productivity was poor.

In the manufacturing process of the optical disc master 1, the master master 12 cannot confirm the state of the recording signal on the master master 12 recording the recording signal, that is, whether or not the signal is accurately recorded. ,
Only after the replica disk 5 was created, it could be judged, and the productivity was poor.

Further, even when the stamper 3 is produced from the master master 12, the state of the recording signal on the stamper 3 cannot be confirmed, so that the determination can be made only after the replica disc 5 is produced, and the productivity is poor. .

In view of the above problems, it is an object of the present invention to judge the quality of the recording state of a recording signal recorded on an optical disc master in a manufacturing process before making a replica disc.

[0014]

Therefore, the present invention according to claim 1 creates an optical disc when the refractive index of the resin substrate of the optical disc is n1 and the wavelength of the laser beam for reproducing a signal through the resin substrate is λ1. For covering the signal groove of the optical disc master with a refraction medium having a refractive index n2, the wavelength λ2 =
It is characterized in that reproduction is performed with a (n2 / n1) × λ1 laser beam through a transparent substrate having a refractive index of n1.

According to a second aspect of the present invention, an optical disk master in which a signal groove is covered with a refractive medium having a refractive index n2, a transparent substrate having a refractive index n1 mounted on the optical disk master, and an optical disk via a transparent substrate are provided. Wavelength λ2 that illuminates the signal groove of the master
= (N2 / n1) × λ1 laser light.

As described above, the optical reproduction condition of the optical disc master can be made equal to the optical reproduction condition of the optical disc (replica disc), and the reproduction condition at the time of reproduction of the replica disc (signal recording on the replica disc) Status) can be confirmed from the recording status of the optical disc master.

[0017]

1 is a schematic diagram showing an embodiment of a reproducing system for an optical disc master according to the present invention. The optical disc master 1 of this embodiment is a stamper 3 having an information recording surface 2 on the surface of which a signal is recorded by a conventional manufacturing process.
The same effect can be obtained even with the master master. According to the present invention, the information recording surface 2 is covered with a refraction medium 4 having a refractive index n2, a transparent substrate 7 corresponding to the resin substrate 6 of the replica disc 5 is placed thereon, and the optical disc master 1 has a wavelength λ2 = Reproduction is performed with a laser beam 8 of (n2 / n1) × λ1.

The manufacture of the optical disc master of the present invention will be described. FIG. 2 is a schematic view showing a manufacturing process of an optical disc master. In FIG. 2, the glass master 9 is coated with the photosensitizer 10, the laser light 8 is modulated based on the signal from the master tape 11, and the photosensitizer 10 on the glass master 9 is exposed. After that, the master master 12 is formed by developing the glass master 9. The master master 12 is covered with a silver conductive film 13, and then nickel plating 14 is applied to the master, and the silver conductive film 13 is removed to form the stamper 3. By covering the stamper 3 with the refraction medium 4,
The optical disc master 1 is completed.

As a method of forming the optical disc master 1 by covering the stamper 3 with the refraction medium 4, for example, a stamper 3 is pressed with resin to form a replica disc.
By installing the stamper 3 in a mold and injecting and pressing the refraction medium 4 into the mold, the optical disc master 1 in which the signal groove portion 15 and the information recording surface 2 are covered with the refraction medium 4 can be obtained. When the refraction medium 4 is water, water is placed on the stamper 3 and the transparent substrate 7 is placed on the stamper 3, so that the water covers the signal groove portion 15 by the transparent substrate 7 to form the optical disc master 1.

A method of reproducing the optical disc master prepared as described above will be described. As shown in FIG. 1, the wavelength λ2 of the laser light 8 for reproduction on the optical disc master 1 is set to (n2 / n
1) × λ1 and the laser beam 8 is focused on the signal groove portion 15 of the information recording surface 2 on the optical disc master 1 to read the recording signal. At this time, the wavelength λ1 is the wavelength of the reproducing laser beam 8 of the replica disk 5, and the refractive index n1 and the thickness t of the transparent substrate 7 do not need to match those of the replica disk 5, and the objective lens Any value that meets the 16 design values may be used.

Laser light 8 of wavelength λ2 = (n2 / n1) × λ1
Passes through the transparent substrate 7 and the refraction medium 4 and converges on the signal groove portion 15 of the information recording surface 2, so that the wavelength at the signal groove portion 15 of the information recording surface 2 of the optical disc master 1 is (1 / n2) × { (N2 / n1) * [lambda] 1} = [lambda] 1 / n1 (1), which is the same as when reproducing the replica disk 5.

For example, in the case of a CD, a reproduction laser beam 8
Wavelength λ1 = 780 nm, and the refractive index n1 = 1.
55. In order to reproduce the optical disc master 1 under the reproduction condition equivalent to that of the CD, if the refraction medium 4 shown in FIG. 1 is water (n2 = 1.33), the wavelength of the laser beam 8 for reproduction of the optical disc master 1 will be described. λ2 is λ2 = (1.33 / 1.55) × 780 (2) = 669 nm.

As described above, by covering the information recording surface 2 of the optical disc master 1 with the refractive medium 4 having the refractive index n2,
Since the reproduction condition of the optical disc master 1 can be made equal to that of the replica disc 5, the quality of the optical disc master or the recorded signal can be confirmed at an early stage of the optical disc manufacturing process. The reproduction conditions of No. 5 (signal recording state on the replica disk 5) can be confirmed, and the productivity is improved.

[0024]

According to the present invention, the optical condition at the time of reproduction of the optical disc master can be made equal to the reproduction condition of the replica disc, so that the quality of the recording state can be grasped at the initial stage of the optical disc manufacturing process. And productivity is improved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a reproduction system of an optical disc master according to the present invention.

FIG. 2 is a schematic view showing a manufacturing process of an optical disc master.

FIG. 3 is a schematic view showing a manufacturing process of a conventional optical disc.

FIG. 4 is a schematic diagram showing a main part of a configuration of a reproduction system of a conventional optical disc.

FIG. 5 is a schematic diagram showing a main configuration part of a reproduction system of a conventional optical disc master.

FIG. 6 is a schematic diagram showing a main part in reproduction of an optical disc.

[Explanation of Codes] 1 ... Optical disc master 2 ... Information recording surface 3 ... Stamper 4 ... Refractive medium 5 ... Repleker disc 6 ... Resin substrate 7 ... Transparent substrate 8 ...・ ・ Laser light 9 ・ ・ ・ Glass master 10 ・ ・ ・ Photosensitizer 11 ・ ・ ・ Master tape 12 ・ ・ ・ Master master 13 ・ ・ ・ Silver conductive film 14 ・ ・ ・ Nickel plating 15 ・ ・ ・ Signal groove 16 ・ ・・ Objective lens 17 ・ ・ ・ Reflective film 18 ・ ・ ・ Protective film 19 ・ ・ ・ Top of information recording surface 20 ・ ・ ・ Bottom of information recording surface

Claims (2)

[Claims] 1. A refractive index of a resin substrate of an optical disk is n1, and a wavelength of a laser beam for reproducing a signal through the resin substrate is λ.
When it is set to 1, the signal groove of the optical disc master for producing the optical disc is covered with the refractive medium having the refractive index n2, and the refractive index n is obtained by the laser light having the wavelength λ2 = (n2 / n1) × λ1.
A method for reproducing an optical disc master, which is characterized in that reproduction is performed through the transparent substrate 1. 2. An optical disk master in which a signal groove is covered with a refractive medium having a refractive index n2, and a refractive index n mounted on the optical disk master.
1 and the wavelength λ2 = (n2 / n1) × λ1 for irradiating the signal groove of the optical disc master through the transparent substrate.
An optical disk master reproduction system, comprising: