KR100474925B1 - High density optical disk and method for fabricating the same - Google Patents

Abstract

The present invention relates to a high-density optical disk and a method for manufacturing the same, and includes a pit formed in the same convex shape at the same position as the glass disc where all portions except the region where the pit is to be formed are exposed. It can skip the mother stamper formation process by using two or three laser lights during the photosensitive process of PR, using the remaining portion as the pit without dimming the pit of the high-density reproduction-only optical disc. By simplifying the process and using a stamper manufactured for the first time, there is no deterioration of the original signal, and at the same time, the formation of a new type of pit improves the characteristics of the signal during reproduction and increases the storage density.

Description

High density optical disk and method for fabricating the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproduction-only optical disc, and more particularly, to a high-density optical disc and a method of manufacturing the same, capable of improving recording density and reproduction signal characteristics by producing a stamper using a plurality of laser lights.

In general, the processing speed of a semiconductor-based data processor is rapidly increased, so that not only multimedia contents including high-definition video and audio signals, but also data associated with the same may be increased. The trend is dominant, and storage media are also becoming higher.

In particular, optical discs are attracting attention among storage media because of their lower cost per capacity than other storage media and the convenience of moving and storing.

There are two types of optical discs, write once read many (WORM) and rewritable types, which can be recorded / played back directly by the appropriate device (eg CD-R drive, CD-RW drive). Some optical disks have a read only memory (ROM) type in which data is supplied to a consumer in a pre-stored state during the optical disc manufacturing process so that the consumer can read the stored data.

Hereinafter, an optical disk and a stamper for manufacturing the same according to the related art will be described with reference to the accompanying drawings.

FIG. 1 is a process configuration diagram for photosensitive portions where a pit is to be formed using a single laser light in the prior art, and FIG. 2 is a cross-sectional view of a glass disc and a stamper configuration using the photosensitive process of FIG. 1.

3 is a configuration diagram of an optical disk substrate formed by the injection molding process using the stamper of FIG. 2, and FIG. 4 illustrates a process of reading information from an existing DVD or CD using the optical disk substrate of FIG. 3 under the substrate. It is a block diagram.

5 is a diagram illustrating a process of reproducing information of a high density optical disk formed by the process of FIGS. 1 to 3 above the substrate of the optical disk, and FIGS. 6A and 6B illustrate a mother stamper made of the stamper of FIG. It is a block diagram which shows the manufacturing process of the used optical disk.

FIG. 7 is a diagram illustrating an information reading process of an optical disk using the optical disk substrate of FIG. 6.

A read-only optical disc (ROM type) has a certain shape of pit during the optical disc manufacturing process.

This unevenness is properly modulated, with unevenness, indicating a digital signal of binary zeros and ones. These irregularities are made along one long spiral in the optical disk, and the user irradiates the laser light to the irregularities to reproduce the original signal with the difference in the amount of reflected light depending on the presence or absence of the irregularities. That is, the portion without the unevenness is a large amount of light reflected, and the portion with the unevenness is less the amount of light is reflected by the light scattered by the unevenness.

And the reproduction-only optical disk is made through an injection molding process from a metal disk called a stamper, as shown in FIG.

To make a stamper, a thin layer of photoresist (PR) is first applied onto a glass plate with a very clean surface.

Then, the laser is irradiated onto the glass disc only to a desired portion to partially expose the PR. PR of the photosensitive part is scraped off through the etching process and has irregularities.

When the uneven surface is thickly coated with metal, the information transmitted through the original laser light is formed in the shape of a spiral track on the metal surface in the form of a pit. This metal disk is called a stamper.

The first manufactured stamper has a pit protruding shape as shown in FIG.

And, as shown in Figure 3, when the injection molding the optical disk substrate using the fabricated stamper, since the shape of the stamper surface is transferred, irregularities having information on the surface of the optical disk substrate is generated and the shape of the irregularities are opposite to the stamper Will have

For example, in the stamper, the optical disk substrate ejected in the case of convex convex and concave becomes concave and convex.

Since the optical disk substrate reproduces information by irradiating a laser beam down the optical disk substrate as shown in FIG. 4, the optical disk substrate has an information reproducing layer having a convex pit shape when the laser light is referenced.

The information contained in the reproduction-only optical disc described above is transmitted through the laser light in the process of photosensitive PR using the laser light.

This laser light enters the PR-coated glass disc through an acoustic-optic modulator (AOM).

The AOM typically contains a crystal inside and is driven by an AOM driver that controls the electrical signal.

The AOM varies the refractive index inside the crystal in minute cycles by electric signals (RF, radio frequency) supplied from the outside, and this change in the periodic refractive index becomes an optical grating. The optical grating thus formed is a device that diffracts laser light incident at a predetermined angle to the AOM.

The diffracted laser light exposes the PR on the glass disc through an optical device such as a lens.

On the other hand, when no optical grating is formed on the crystal inside the AOM, the laser beam passing through is not diffracted and continues straight. The straight laser light does not reach the glass disc and thus does not expose the PR.

Therefore, if the magnitude of the electrical signal supplied to the AOM is changed over time, the laser beam can be turned on and off on a rotating glass disc, thereby forming pits according to spiral tracks.

Injection molding using the stamper thus manufactured forms pits in the molded optical disk, and as a result, information stored in the optical disk for reproduction is obtained.

In order to achieve high density on the optical disk, laser light (wavelength from blue light source to 400 nm) with a shorter wavelength is used and a numerical aperture (NA) is larger than conventional laser light (wavelength from red light source to 650 nm). The use of a lens reduces the spot size of the light source and increases the density of information storage on the disk surface.

This is because the spot size becomes small in proportion to the wavelength, and the recording density is inversely proportional to the square of the spot size.

In using the objective lens having a large numerical aperture NA, the objective lens and the information storage layer of the optical disk should be close to the high density storage.

This is because when the distance between the objective lens and the information storage layer is far while reproducing from the high density optical disk using the large NA lens, the aberration greatly increases as the optical disk which may occur during reproduction is inclined.

In addition, coma aberration has a characteristic proportional to the cube of NA.

Therefore, in high density optical discs, an information storage layer is formed as close to the disk surface as possible to narrow the distance between the objective lens and the information storage layer.

In the prior art, as shown in FIG. 5, a reflective film is formed on a 1.1 mm optical disk substrate, and then a thin cover layer of 0.1 mm is formed so that laser light reproduces information through the protective layer. .

In addition, since it is very difficult to transfer information to a thin layer (0.1 mm cover layer) using a stamper having the information recorded on the optical disk in an uneven form, a 1.1 mm disk substrate is injection molded to provide information on the substrate. I'm using a method to make it transfer.

In the prior art, reproduction of information recorded on an optical disc is performed as follows.

In the prior art, when a stamper for a CD or a DVD is produced, a pit is formed by using one laser light, and the pit means the information itself of the disc in a reproduction-only optical disc.

However, the optical disk produced by such a CD or DVD, as shown in Figure 4, by reading the laser light to the lower side of the substrate to read the information according to the amount of reflected light.

At this time, the pits, i.e., the uneven portion has a small amount of light reflected by the unevenness, and the flat portion without the unevenness has a larger amount of reflected light than the uneven portion, and thus shows different states.

However, when making the stamper, the electrical signal entering the AOM needs to be put in a certain size to diffract the laser for the pit part (binary digit 0 on the optical disk), and the part without the pit does not put the electrical signal. Will not diffract.

In other words, an electrical signal of binary 1 is required for the pit part read from the actually manufactured disk, and an electrical signal of binary 0 must be supplied through AOM for the high reflectivity part because there is no pit.

Therefore, when a high density optical disk substrate is fabricated using the stamper manufactured in this manner, and the signal is read from the upper side of the optical disk substrate rather than the substrate, the pit shape becomes concave rather than convex.

When the signal is reproduced from such an optical disk, deterioration of signal characteristics such as jitter is expected as compared with the convex pit shape, and the tracking necessary for reading the signal may be more difficult.

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Therefore, convex pits are advantageous even in high-density optical discs for reproduction. To create a high-density optical disc substrate for reproduction with convex pits, a mother stamper must be made using the original stamper made from the first etched PR.

6A and 6B illustrate a process of making a mother stamper from an original stamper and again manufacturing an optical disk substrate using the mother stamper.

Since the mother stamper has a shape of the pit opposite to that of the original stamper, the optical disk injection-molded using the mother stamper has a convex pit as shown in FIG. 7.

However, the process of forming the optical disk of the prior art and a stamper for manufacturing the same has the following problems.

First, reproducing a signal from an optical disk having a concave pit shape is expected to deteriorate signal characteristics such as jitter, and also make it more difficult to track essential for reading out the signal.

Second, in order to solve this problem, in order to make an optical disk having a convex shape, a process of making a mother stamper is required, which is disadvantageous in terms of mass production.

Third, the pit shape may change in shape compared to the original stamper during the manufacture of the mother stamper from the original stamper.

Fourth, optical disks manufactured by using an injection molded optical disk substrate using a mother stamper have poor signal reproduction characteristics compared to optical disks made using an original stamper.

This is because the transfer characteristics from the original stamper are hardly 100% when the mother stamper is made.

Fifth, even if the optical disc is made using a mother stamper, signal degradation such as jitter due to the pit is elliptical cannot be fundamentally avoided. The surface condition of the missing portion is determined by the PR surface, which can lead to signal degradation due to surface roughness that may occur during the PR coating process.

SUMMARY OF THE INVENTION The present invention solves the problem of the prior art optical disk and the process of forming a stamper for manufacturing the same, and can improve recording density and reproduction signal characteristics by manufacturing a stamper using a plurality of laser lights. It is an object of the present invention to provide a high density optical disk and a method of manufacturing the same.

The high-density optical disc according to the present invention for achieving the above object is the same as that of the glass disc in which all parts other than the area where the pits are to be formed are the same in the information recording medium manufactured by using the same. It characterized in that it comprises a pit formed in the convex shape of the same shape at the position.

The method for manufacturing a high density optical disc according to the present invention includes the steps of: exposing and etching a PR of a second area excluding a first area where pits are to be formed by using a plurality of laser lights on the PR of a glass disc; Forming a stamper having a concave pit in a first region by using a glass disc; and forming an optical disk having a convex pit in a first region by using the stamper.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Hereinafter, a high density optical disk and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 8 is a diagram illustrating a photosensitive portion of a portion excluding a pit forming region using two laser lights according to an exemplary embodiment of the present invention.

FIG. 9 is a cross-sectional view of a glass disc according to the photosensitive process of FIG. 8 and a stamper using the same, and FIG. 10 is a diagram illustrating an information reading process of an optical disk manufactured using a stamper using the photosensitive process of FIG. 9.

The present invention allows the formation of a pit of a high-density reproduction-only optical disc using a two or more laser lights in a new shape. The position and shape of the pit can also be changed so that an additional signal can be stored in the position and shape of the pit. It is.

This also reduces the size of the pit, which is limited by the wavelength of the laser light, which makes it possible to effectively improve the storage density.

In the present invention, as shown in Fig. 8, when photosensitive PR on a glass master plate using laser light, two laser beams are used simultaneously to form a pit of a high-density reproduction-only optical disc.

That is, as shown in Figure 8 showing the use of two laser light when the photosensitive PR, the laser light ① and the laser light ② when irradiated at the same time to irradiate the glass plate 91 so as to overlap with each other.

As the glass master plate 91 rotates, the laser light ① emits a modulation signal for forming a pit, and the laser light ② irradiates a space between the pit and the pit.

At this time, the power of the laser light ① and the laser light ② is sufficiently large so that when the two laser lights are turned on at the same time, all the PR (photoresist) 92 located between the laser lights is irradiated.

This principle causes the PR 92 on the glass master 91 to be exposed to the required radius.

Thereafter, the PR irradiated through the etching process is etched, and the first produced stamper 93 has a shape as shown in FIG. 9.

The stamper 93 formed by such a process allows the optical disk substrate 100 to have a convex pit even when immediately used for injection molding without a process of making a mother stamper as shown in FIG. 10.

This is because when using two laser beams to expose the PR, the original stamper is made of a concave-convex shape unlike the structure of FIG. This is because they are opposite to each other.

In addition, since the power of the laser light ① for forming the pit was increased, the pit formed was close to a rectangle.

This further improves the characteristics of the reproduction signal such as jitter when reading information using laser light from the reproduction-only optical disc.

When the laser beam is irradiated to the glass plate coated with PR in order to make the stamper of this shape, if the rotation direction of the glass plate is irradiated in a counterclockwise direction with respect to the objective lens, even when the information is reproduced from the final optical disk Also, it plays back counterclockwise around the objective lens.

According to the manufacturing process of the present invention, since two laser beams are exposed to portions other than the pit, a much smaller pit can be manufactured, improving the recording density, and making the width of the pit of all lengths uniform, thereby reproducing the signal. Improve the characteristics.

The laser irradiation apparatus and the PR photosensitive process using the same for the stamper and the optical disk manufacturing process using the same will be described below.

FIG. 11 is a configuration showing an example of a laser irradiation apparatus for applying to a stamper of the present invention and an optical disc using the same.

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The laser beam recorder (LBR) of FIG. 11 is an example for manufacturing a stamper for an optical disc for high-density reproduction using two laser beams, and has two AOM (Acousto Optic Modulator).

First, after passing through various optical instruments, the laser output unit (Laser) that outputs short-wavelength laser light used for photosensitive PR on the glass disc, and the laser light power is adjusted according to the PR photosensitive conditions. Electro-optic modulator (EOM) that removes noise components mixed with laser light, polarization beam splitter (PBS) that passes only laser light of constant polarization among laser light emitted through EOM, and laser light at an appropriate ratio The response time of the beam splitter (BS1) (BS3) which divides, the PD-1 (photo detector) which measures the EOM output which the EOM acts as a feedback system, and the AOM (Acousto Optic Modulator) To focus the laser light at the front end of the AOM, enter the AOM, and the laser light that passes through the AOM is returned to the lens L1, L2, L3, L4, and the like. XYBS1, XYBS2 (XY Beam Shifter) for moving the optical axis of the laser light, a beam splitter (BS2) (BS4) for dividing the laser light in a constant ratio, and transmits or reflects according to the polarization state of the incident laser light When the beam steerer (BST), the half wave plate (HWP) that changes the polarization direction of the incident linearly polarized light, and the polarization direction of the linearly polarized laser light are incident at a constant angle, the circular polarization In the process of converting and converting the returned circularly polarized light into linearly polarized light, the converted linearly polarized light has an angle of 90 degrees with the original linearly polarized light so that the reflected laser light does not return to the original light source. QWP (quarter wave plate), which serves to protect the laser light source, a photo detector PD-2 (PD-3) for measuring the power of each laser beam, and a mirror M1. And an objective lens (OBJ) for focusing the incident laser light to a very small size.

Using this LBR system, one laser light applies a modulation signal through the AOM to form a pit, and the other laser light is adjusted to have a proper power through the other AOM, and the beam continues to pass without modulation. Try to light the glass disc.

Here, the AOM used for photosensitive laser light can adjust the power of the laser light so that the width of the photosensitive light can be adjusted.

As such, when using two laser lights, one is used to determine the presence or absence of the pit and the length of the pit to represent a modulated binary digit, and the other laser light is the portion between the pit and the pit. It is used to determine the width of the pit by dimming the PR.

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Here, if the power of the laser light used to make the pit shape is increased, the curvature of the end of the pit shape can be adjusted, and if a sufficiently large power is used, a pit shape close to the square can be formed.

As such, the curvature at the tip of the pit can be adjusted to a level comparable to the laser spot size used when reading signals from the optical disk, so that the signal can be read better during playback.

FIG. 12 shows another embodiment of an LBR for photosensitive PR using two laser lights as in FIG. 13.

12 is configured such that the laser light for forming the pit passes not only the AOM for modulation but also the AOD to change position.

The welded cylindrical lens (CYL1,2) configured at both ends of the AOD is for maintaining the proper angle and incidence when the laser light is incident on the AOD.

In addition, BEX (beam expander) is to increase the size of the laser light to ultimately have a laser spot size when the PR photosensitive. And Figure 13 is a block diagram showing a PR photosensitive process using the laser irradiation apparatus of FIG. 14 is a block diagram showing the information reproduction process of the optical disk using a stamper formed by the method of FIG. 13. PR photosensitive using the LBR system is such that the two laser lights ①② do not overlap each other, as shown in FIG. The position of the laser light to form the pit is changed to an AOD (acousto-optic modulator) to expose the PR. In other words, the laser light ① is to change the position of the PR light, thereby adjusting the position of the photosensitive light. The recording density can be further improved in the case where the degree of positional variation of the laser light? Is made into several stages. This shows the process of reproducing information from an optical disk made by using a stamper using the same. To reproduce the information, the difference between the left and right sides (up and down of the laser light in the drawing) due to the difference in reflectance of the laser light is push-pushed ( This signal is called a push-pull signal, and when the signal is read, separate information can be stored by changing the position of the pit in addition to the information of the presence or absence of the pit, thereby improving the information storage density of the optical disk.

Hereinafter, a manufacturing process of a stamper and an optical disc using three laser lights according to another embodiment of the present invention will be described.

15 is a block diagram showing a photosensitive process for forming pits using three laser lights according to the present invention.

FIG. 16 is a diagram illustrating a process of reproducing information of an optical disk using a stamper formed by the method of FIG. 15, and FIGS. 17, 18, 19, and 20 are methods of varying position change signals of three laser lights. It is an example of a pit shape formed by the.

15 shows the use of three laser lights to vary the position of the pit.

The shape of each pit can be varied by appropriately adjusting three positions of the laser light, and thus, various types of pit shapes can be realized.

That is, it shows the process of photosensitive so that the position and shape of the pit can be changed while at the same time the stamper produced by using the three laser light to reduce the PR can be used for injection molding.

Among the three laser lights, the laser light ② having the greatest power is used to determine the presence or absence of the pit and the length of the pit. The laser light modulated by NRZI (Non Return to Zero Inverted recording).

The other two laser lights are used to determine the width of the pit by exposing it between the pit and the pit.

By simultaneously inputting the same amount of signal to each AOD through which these three light passes, it is possible to change the position of the three beams at the same time, thereby changing the position of the pit of the same shape.

FIG. 16 illustrates a process of reading an optical disc made by using a stamper manufactured by the method of FIG. 15, and it can be seen that the pits are convex and the formation positions thereof are variable.

In addition, the shape of the pit can be varied by applying a modulation signal and a position variable signal to the laser light ② and a position variable signal different from the laser light ② to the laser light ① and ③.

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17, 18, 19, and 20 show such shapes, and various shapes of pits are realized by appropriately adjusting the power and position signals of the laser lights ①, ②, ③.

FIG. 21 is a configuration diagram showing an example of a laser irradiation apparatus for applying to the photosensitive process for forming the pits of FIGS. 15, 17, 18, 19, and 20, and FIG. 22 shows FIGS. 15, 17, It is a block diagram which shows the other example of the laser irradiation apparatus for applying to the photosensitive process for forming the pit of FIG. 18, FIG. 19, FIG.

FIG. 21 illustrates an example of photosensitive PR using three laser lights, and FIG. 22 illustrates a case in which a beam monitoring system is separately configured.

In the LBR system of FIG. 21, an NRZI signal for forming a pit is input to one of three AOMs, and an adjustable constant value is input to the other two AOMs.

AOD is used to change the position of the laser light.

As described above, in the present invention, the pit size is not determined by the spot size of the focused laser light, which is determined by the wavelength of the laser light and the numerical aperture NA of the objective lens to be used. In the case of forming a pit with two beams as described above, a small pit can be easily manufactured since the pit size is determined by reducing the distance between the two beams and the distance between the tracks.

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Similarly, as shown in FIG. 15, when three laser lights are used, the width between the laser light ① and the laser light ③ can be narrowed and the track spacing can be reduced at the same time. It is possible to reduce and improve the recording density, which effectively improves the recording density by overcoming the existing technology in which the spot size of the laser is determined by the wavelength and the recording density is physically limited by the spot size.

Thus, by using two or more laser lights to etch portions other than the pit, the width of the pit of all lengths can be made uniform, so that the reproduction signal characteristics can be improved. By etching parts other than the pits, the large reflectance surface is determined by the glass surface instead of the PR surface formed during the process of optical disk regeneration, thereby eliminating signal degradation that may occur during the PR coating process. do.

Such a high density optical disk and its manufacturing method according to the present invention has the following effects.

First, the present invention uses a two or three laser light in the photosensitive process of the PR, and a mother stamper forming process by using the remaining portion as a pit without dimming the pit of the high-density reproduction-only optical disk It can be skipped, which simplifies the process.

Second, there is no deterioration of the original signal by using the stamper produced for the first time, and the effect of improving the characteristics of the signal during reproduction is formed by forming a new type of pit at the same time.

Third, it is possible to make a smaller pit by overcoming the existing technology in which the minimum size of the pit formable by the laser wavelength and the objective lens is determined, thereby improving the recording density.

Fourth, it is possible to obtain a push-pull signal at the time of signal reproduction, so that not only the information held by the pit, but also the information stored according to the pit position can be improved, thereby improving the recording density.

Fifth, since portions other than the pit are exposed by two or more laser lights, a pit having a uniform width can be formed from the smallest pit to the longest pit, thereby improving reproduction signal characteristics.

Sixth, the size of the pit can be made close to a square, which improves the characteristics of the playback signal. Seventh, the position and shape of the pit can be varied, so that a separate signal can be stored, for example, to prevent disc copying, and thus the recording density. Eighth, since the high reflectivity surface is determined by the glass surface instead of the PR surface formed during the process of optical disk regeneration, the signal degradation that may occur during the PR coating process is eliminated at the source.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

1 is a process configuration diagram for photosensitive portions where pits will be formed using one laser light in the prior art;

2 is a cross-sectional view of the glass disc by the photosensitive process of FIG. 1 and a stamper configuration using the same

3 is a block diagram of an optical disk substrate formed by the injection molding process using a stamper of FIG.

4 is a diagram illustrating a process of reading information from an existing DVD or CD using the optical disk board of FIG. 3 to the bottom of the board.

5 is a diagram illustrating a process of reproducing information of a high density optical disk formed by the process of FIGS. 1 to 4 above the optical disk substrate.

6A and 6B are diagrams illustrating an optical disk manufacturing process using a mother stamper made of the stamper of FIG.

FIG. 7 is a diagram illustrating a process of reading information of an optical disk using the optical disk substrate of FIG. 6B. FIG.

8 is a configuration diagram showing the photosensitization of the portion excluding the pit formation region using two laser lights according to an embodiment of the present invention.

9 is a cross-sectional view of the glass disc by the photosensitive process of FIG. 8 and a stamper configuration diagram using the same;

FIG. 10 is a configuration diagram illustrating an information reading process of an optical disk manufactured by using a stamper by the photosensitive process of FIG. 9.

11 is a block diagram showing an example of a laser irradiation apparatus for applying to the stamper of the present invention and the manufacturing process of the optical disk using the same.

12 is a configuration diagram showing another example of a laser irradiation apparatus for applying to a stamper of the present invention and an optical disc using the same;

FIG. 13 is a configuration diagram illustrating a PR photosensitive process using the laser irradiation apparatus of FIG. 12. FIG.

14 is a configuration diagram showing an information reproducing process of an optical disc using a stamper formed by the method of FIG.

15 is a block diagram showing a photosensitive process for forming a pit using three laser light according to the present invention

16 is a configuration diagram showing an information reproducing process of an optical disc using a stamper formed by the method of FIG.

17, 18, 19, and 20 are diagrams showing still another example of a new pit shape formed by a method of varying position change signals of three laser lights.

21 is a configuration diagram showing an example of a laser irradiation apparatus for applying to the photosensitive process for forming the pit of FIG. 15 and the pit of FIGS. 17, 18, 19, and 20.

22 is a configuration diagram showing another example of a laser irradiation apparatus for applying to the photosensitive process for forming the pit of FIG. 15 and the pit of FIGS. 17, 18, 19, and 20;

Explanation of symbols for the main parts of the drawings

91.Glass Disc 92.PR

93. Stamper 100. Optical Disc Substrate

Claims (16)

In an information recording medium selectively photosensitive PR on a glass disc and manufactured using the same, And a pit formed in the same convex shape at the same position as that of the glass original plate in which the PR of the second area other than the first area where the pit is to be formed is all exposed and the PR pattern having the convex shape exists in the first area. High density optical disk. 2. The high density optical disc of claim 1, wherein the widths of all the pits are constant regardless of the length of the pits. The high-density optical disc according to claim 1, wherein the pit is not aligned with respect to the same track and the position is changed so that other information is stored in addition to the information held by the pit according to the degree of change of the position. 4. The high density optical disc according to claim 3, wherein additional information is stored in addition to the presence or absence of the pit and the information of the pit position according to the degree of change of the pit shape. Dimming and etching the PR of the second region except for the first region in which the pit is to be formed by using the plurality of laser lights on the glass disc so that the PR patterned in the first region remains convex; Forming a stamper having a concave pit in the first region by using a glass disc from which the PR is selectively etched; Using the stamper to form an optical disk having the same convex pit in the same first region as the patterned PR on the glass disc. 6. The method of claim 5, wherein in the step of photosensitive PR, one of the laser lights irradiates a modulation signal for determining the presence or absence of the pit and the length of the pit, and the other of the laser light irradiates the space between the pit and the pit. A method for producing a high density optical disc, characterized in that the width of the pit is determined. The method of manufacturing a high density optical disc according to claim 6, wherein the width at which the PR is exposed is adjusted by varying the power of the laser light irradiated between the pit and the pit. 7. The method of manufacturing a high density optical disc according to claim 6, wherein the pit shape becomes rectangular in shape as the power of laser light for irradiating a modulation signal increases. 7. The method of manufacturing a high density optical disc according to claim 6, wherein when the laser lights are irradiated simultaneously, the laser lights are irradiated such that the irradiated areas overlap with each other. 7. The method of claim 6, wherein the laser lights are irradiated so that they do not overlap each other when the laser lights are irradiated, and the position of the laser light irradiating a modulation signal for forming a pit is varied by an acoustic optic modulator (AOD). A manufacturing method of a high density optical disk, wherein the pit formation position is different. 6. The rotation according to claim 5, wherein the rotation direction of the glass substrate during the irradiation of the laser light in the PR photosensitive step with respect to the objective lens and the irradiation of the laser light for information reproduction of the optical disk having convex pit formed in the first region. The manufacturing method of the high density optical disk characterized by the same direction. 6. The method according to claim 5, wherein in the step of photosensitive PR, one of the laser lights irradiates a modulation signal for determining the presence or absence of the pit and the length of the pit, and the other two of the laser lights irradiate the space between the pit and the pit. And determining the width of the pit. 13. The method of manufacturing a high density optical disc according to claim 12, wherein the laser light for determining the presence or absence of the pit and the length of the pit is located at the center of the other two laser lights. 13. The method according to claim 12, wherein the position of the irradiation area is varied by inputting an appropriate position change signal to the AOD simultaneously to three laser beams so that the pit formation position and the pit shape can be varied in various ways so that additional information recording is possible. The manufacturing method of the high density optical disk characterized by the above-mentioned. 6. The method of claim 5, wherein the size of the pits is not limited to the wavelength of the laser. 6. The optical disc manufacturing method according to claim 5, wherein a signal having a large reflectance at the time of optical disc reproduction is not affected by the surface state of the PR but by the surface state of the glass.