JPH0817067A - Optical information recording and reproducing device and optical disk original disk manufacturing device - Google Patents

Abstract

PURPOSE:To make the recording density high by reducing the diameter of a converged light spot on an optical disk. CONSTITUTION:Information is recorded by using reversible variation or irreversible variation which is caused by irradiation with laser light, and the variation is optically detected with the laser light to reproduce the information. This device is equipped with the optical disk 1 and an optical head 2 having at least a laser light source and a condenser lens which converges the laser light emitted by the laser light source, and liquid 7 with a high refractive index is charged between the optical disk 1 and the condenser lens of the optical head 2. Consequently, the converged light spot diameter is reducible, a signal drop in a high frequency area is small as compared with recording and reproduction by conventional substrate incidence, and a fine mark can stably be recorded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus and an optical disk master manufacturing apparatus, and more particularly to an optical information recording / reproducing apparatus and an optical disk master manufacturing for achieving high recording density by reducing the diameter of a focused spot. Regarding the device.

[0002]

2. Description of the Related Art An optical disk recording system using a laser beam is capable of large-capacity recording and can be accessed at high speed in a non-contact manner. The optical disc medium (hereinafter referred to as an optical disc) is a read-only type known as a compact disc or a laser disc, a write-once type that can be recorded by the user himself, and a rewritable type that can be repeatedly recorded / erased by the user. are categorized. The write-once and rewritable optical disks are about to be used as external memory, document files, and image files of computers.

In an optical disc using a laser beam,
In order to achieve a high recording density, the laser light used for recording / reproducing is focused and used near the theoretical limit. That is, assuming that the numerical aperture of the condenser lens used for condensing is NA, the wavelength of the laser used is λ, and it is assumed that ideal parallel light is incident on the condenser lens, The diameter φ (the diameter at which the power becomes 1 / e ² ) is theoretically φ = (1.22 × λ) / NA (for example, by Koyama and Nishihara, Lightwave Electronics, p6
6, Corona).

Therefore, in order to reduce the laser spot diameter in order to achieve high recording density, it is understood that methods such as shortening the laser wavelength and increasing the NA of the lens are effective.

First, regarding the wavelength of the laser in the item, at present, in the optical disc, a semiconductor laser which oscillates in the near infrared of 780 to 830 nm is predominant. Recently, a semiconductor laser that oscillates red light in the 690 nm band is approaching a practical level, and further, a short-wavelength laser is still at a research level and is far from reaching a practical level.

[0006] Next, regarding the NA of the lens in the item (1), in a normal optical disc recording / reproducing apparatus, information is recorded / reproduced through an optical disc substrate having a thickness of about 1.2 mm.
At present, NAs of about 0.5 to 0.55 are used. Therefore, in order to increase the NA, it is necessary to take measures such as increasing the diameter of the lens or reducing the thickness of the optical disk substrate. Therefore, at present, the NA is at most 0.6 or less.

Further, an optical disk master manufacturing apparatus is used for manufacturing a high recording density optical disk typified by a CD-ROM and the like, and since this also achieves a high recording density, the light source has an Ar wavelength of around 400 nm. An ion laser is used, and a high NA lens with an NA of about 0.9 is used as the condenser lens, but at present, a wavelength that is considerably close to the limit is used.

[0008]

As described above, in the recording / reproducing of information using an optical disc and the production of a master disc of an optical disc, the spot diameter of the laser is almost determined by the wavelength of the laser used and the usage form of the optical disc. is there. For example, using a red light semiconductor laser of 690 nm,
Even if the unfocused light with the numerical aperture NA of 0.6 is adopted, the diameter of the focused light spot is about 1.1 μm at the minimum, which causes a problem that the recording density is limited.
Further, the conventional optical disk master manufacturing apparatus uses almost the wavelength limit, and some improvement is required for future high recording density.

The object of the present invention is to be independent of the form of the optical disk, and by introducing a simple method, an optical information recording / reproducing apparatus and an optical disk master manufacturing apparatus exceeding the limit of the conventional reduction of the focused spot diameter. To provide.

[0010]

The optical information recording / reproducing apparatus of the first invention records information by a reversible change or an irreversible change caused by irradiation of a laser beam, and uses the laser beam for the change. An optical information recording / reproducing apparatus for reproducing the information by optically detecting, the optical disk medium, a laser light source for irradiating at least the laser light, and a laser light condensing laser light radiated from the laser light source. An optical head having an optical lens is provided, and a space between the optical disk medium and the condenser lens of the optical head is filled with a high refractive index liquid.

Further, the optical disk master manufacturing apparatus of the second invention irradiates a laser beam on the resin film which undergoes photochemical change,
An optical disk master manufacturing device for recording information by photochemical changes that occur therein, wherein an optical disk master coated with the resin film, a laser light source for irradiating the laser light,
A condenser lens for condensing the laser light emitted from the laser light source is provided, and a space between the optical disc master and the condenser lens is filled with a high refractive index liquid.

These high-refractive-index liquids are composed of any one of zedel oil, cargill oil, soda oil, ginger oil, cassia oil, α-monochloronaphthalene, α-monobromnaphthalene, and methylene iodide. May be.

[0013]

The present invention is intended to reduce the diameter of the condensing spot diameter of the laser light with a simple structure. Specifically, it is provided between the condensing lens and the optical disk or between the condensing lens and the master. By filling the space with a liquid having a high refractive index, the NA of the condenser lens is increased.

Here, when a liquid having a refractive index of n is filled between the optical disc and the condenser lens, the NA of the condenser lens is (n × NA). It can be reduced to 1 / n as compared with the case where there is no high refractive index liquid. For example, when a liquid having a refractive index of n = 1.2 is used, the focused spot diameter can be reduced to about 80% as compared with the case where this liquid is not used. further,
When the refractive index is n = 1.5, it is about 66%.

[0015]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a view showing the schematic arrangement of an embodiment of the optical information recording / reproducing apparatus of the present invention. In the optical information recording / reproducing apparatus of the present invention, as shown in FIG. 1, an optical disk 1 having a recording film 1a is connected to a spindle motor 3 and is rotationally driven at a predetermined rotational speed. A laser drive signal is supplied from the signal processing circuit 4 to the optical head 2 based on the recording signal 5, and a read signal received by a photodetector (not shown) provided in the optical head 2 is processed by the signal processing. The reproduced signal 6 is output from the circuit 4. Also, the optical head 2 is
In order to perform positioning at a desired position from the inner circumference to the outer circumference of the optical disk 1, it is mounted on a positioning drive mechanism (not shown) and is configured to be movable. A high-refractive index liquid 7 is filled between the optical head 1 and the optical head 2 for recording and erasing information on the optical disc 1.

The high refractive index liquid 7 can be used as long as it is non-volatile and does not adversely affect the constituent members of the optical disc 1. For example, Zedel oil (n = 1.
5), cargill oil (n = 1.5), soda oil (n = 1.
50), butterbur oil (n = 1.53), cassia oil (n
= 1.60), α-monochloronaphthalene (n = 1.6
4), α-monobromonaphthalene (n = 1.66), methylene iodide (n = 1.74) and the like can be used.

The high-refractive-index liquid 7 may be filled between the optical disk 1 and the condenser lens (not shown) of the optical head 2, and as shown in FIG. A configuration in which it is immersed in the liquid 7 may be used. In addition, as the optical disc 1 rotates, the high refractive index liquid 7 becomes
And between the condenser lens of the optical head 2 and
The high refractive index liquid 7 may be filled only on the recording surface side of the optical disc 1, that is, on the side where the optical head 2 is arranged.

Next, the results of trial manufacture of the optical information recording / reproducing apparatus according to the present invention will be described. The optical disc 1 has
Track pitch 1.0 μm, disk diameter 130 mmφ,
A magneto-optical disk medium having a substrate thickness of 1.2 mm was used. A TbFeCo film is formed as a recording film on the magneto-optical disk medium and is covered with a SiN protective film from both sides in a sandwich shape. This prototype device has a configuration in which recording / reproduction is performed from the film formation surface side without passing laser light through the substrate. Then, the optical disc 1 and the wavelength 690 nm, NA0.
“Zedel oil” as the high refractive index liquid 7 was filled between the objective lens 6 and the optical head 2 mounted thereon.

In this state, the spindle motor 3 rotates the optical disk 1 at a rotation speed of 900 rpm, and the recording power: 8 mW, the reproducing power: 1 mW, and the bias magnetic field:
When recording / reproducing was performed while changing the recording frequency under the test condition of 3000 Oe, compared to the conventional recording / reproducing by incidence on the substrate, the signal drop in the high frequency range was small and the minute mark could be recorded stably. confirmed.

FIG. 2 is a view showing the schematic arrangement of an embodiment of the optical disk master manufacturing apparatus of the present invention. As shown in FIG. 2, the optical disk master manufacturing apparatus according to the present invention includes a resin film 11a.
Optical disc master coated with (hereinafter referred to as master) 11
Is connected to the spindle motor 13 and driven to rotate at a predetermined rotation speed. Laser light 1 emitted from the laser light source 14
5 is modulated by the modulator 16 which receives the recording signal. Further, the master 11 and the spindle motor 13 are mounted on a positioning drive mechanism (not shown) and configured to be movable in order to perform positioning at desired positions from the inner circumference to the outer circumference of the master 11. A high refractive index liquid 17 is filled between the master 11 and the condenser lens 12.

As the high refractive index liquid 17, the same liquid as that used in the above-mentioned optical information recording / reproducing apparatus can be used. This high-refractive-index liquid 17 is composed of the master 11 and the condenser lens 12.
It suffices that it is filled between the two, and as shown in FIG. 2, the master 11 may be immersed in the high refractive index liquid 17. In addition, as the master 11 rotates, the high refractive index liquid 17
As long as it is not dispersed between the master 11 and the condenser lens 12, the high refractive index liquid 17 may be filled only on the side where the condenser lens 12 is arranged.

Next, a trial production result of the optical disk master manufacturing apparatus according to the present invention will be described. As the master 11, a glass master coated with an ultraviolet curable organic resin film is used,
Between this master 11 and the condenser lens 12 with NA 0.9,
As the high refractive index liquid 17, “butterfly oil” was filled. Then, the laser light source 14 for exposure has an A wavelength of 458 nm.
Spindle motor 1 with r-ion laser
From No. 3, the master 11 was rotated at a rotation speed of 900 rpm for exposure. As a result of the test, it was confirmed that there is an improving effect on the forming ability of the fine marks as compared with the conventional method.
In particular, the contrast of the edge shape of the mark was improved.

[0024]

As described above, according to the present invention, it has been found that a high recording density can be easily realized by interposing a high refractive index liquid between an optical disc medium or an optical disc master and a condenser lens. This is a novel one that exceeds the limit of the conventional reduction of the focused spot diameter, and has the effect of further promoting the high recording density of the optical information recording / reproducing apparatus and the optical disc master manufacturing apparatus.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of an optical information recording / reproducing apparatus of the present invention.

FIG. 2 is a diagram showing a schematic configuration of an embodiment of an optical disc master manufacturing apparatus of the present invention.

[Explanation of symbols]

 1 Optical Disc 1a Recording Film 2 Optical Head 3,13 Spindle Motor 4 Signal Processing Circuit 5 Recording Signal 6 Reproduction Signal 7,17 High Refractive Index Liquid 11 Master Disk 11a Resin Film 12 Condensing Lens 14 Laser Light Source 15 Laser Light 16 Modulator

Claims (4)

[Claims] 1. An optical information recording / reproducing method for reproducing information by recording information by reversible change or irreversible change caused by irradiation of laser light and optically detecting the change using laser light. An optical disk medium, an optical head having at least a laser light source for irradiating the laser light, and an optical head having a condenser lens for condensing the laser light emitted from the laser light source, the optical disk medium and the optical head An optical information recording / reproducing apparatus characterized in that a space between the condenser lens and the condenser lens is filled with a high refractive index liquid. 2. The high refractive index liquid comprises any one of zedel oil, cargill oil, soda oil, clove oil, cassia oil, α-monochloronaphthalene, α-monobromonaphthalene, and methylene iodide. The optical information recording / reproducing apparatus according to claim 1, which is characterized in that: 3. An optical disk master manufacturing apparatus for irradiating a laser beam onto a resin film which undergoes a photochemical change, and recording information by the photochemical change generated therein, comprising: an optical disk master coated with the resin film; and the laser beam. And a condenser lens for condensing the laser light emitted from the laser source, and a space between the optical disc master and the condenser lens is filled with a high refractive index liquid. Optical disc master making device. 4. The high refractive index liquid comprises any one of Zeder oil, cargill oil, soda oil, sardine oil, cassia oil, α-monochloronaphthalene, α-monobromonaphthalene, and methylene iodide. 4. The optical disk master manufacturing device according to claim 3, which is characterized in that.