JP2000163792A - Optical head and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provider an optical head and an optical disk device capable of recording or reproducing on/from an optical disk with a signal recording surface formed on the backside of a substrate and an optical disk with a signal recording surface on the front surface of a substrate. SOLUTION: This optical head 1 is composed of an object lens 2 and an optical unit 3. The optical unit 3 has a correction board 5 and an SIL(Solid Immersion Lens) 6, and is arranged movable between a position under the object lens 2 and a position off that position under the object lens 2. When recording or reproducing on/from a high density optical disk 100, the optical unit 3 is moved to the position under the object lens 3, and a laser light beam is transmitted through the object lens 2 and the correction plate 5 and the high density optical disk 100 is irradiated with the laser light beam via the SIL 6. When recording or reproducing on/from a low density optical disk, the optical unit 3 moves to a position off the position under the object lens 2, and the low density optical disk is irradiated with the laser light beam through the object lens 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head and an optical disk apparatus used for recording or reproducing information on an optical disk.

[0002]

2. Description of the Related Art Conventionally, optical disks such as DVDs (digital video disks) have been used for recording and reproducing information. Also, a near-field (near-field) recording / reproducing method has been proposed as a technique for increasing the surface recording density of an optical disc. This near-field recording / reproducing method is a technique for reducing the beam spot diameter beyond the diffraction limit of a normal objective lens. By reducing the beam spot diameter, the areal recording density on the optical disk can be further increased.

FIG. 15 is a schematic diagram showing an optical system of a conventional recording / reproducing optical disk device, and FIG. 16 is a schematic diagram showing an optical system of a near-field recording / reproducing optical disk device.

As shown in FIG. 15, in an optical disk 400 such as a DVD, a signal recording surface 402 is formed on the back surface of a transparent substrate 401. Therefore, the laser light is transmitted through the transparent substrate 401 of the optical disk 400 by the objective lens 50 and is irradiated on the signal recording surface 2 on the back surface side.
In this case, the focus of the objective lens 50 is
Is set on the signal recording surface 402.

As shown in FIG. 16, a signal recording surface 502 is formed on the front side of a substrate 501 in an optical disk 500 used for the near-field recording / reproducing method. The laser light is narrowed down by the objective lens 51 and S
The light is incident on an IL (Solid Immersion Lens) 52.

[0006] The SIL 52 is obtained by flattening and polishing a part of a sphere made of a transparent material having a large refractive index such as glass. The focal point of the laser light incident on the SIL 52 coincides with the polished surface, and the polished surface corresponds to the laser light emission surface.

Assuming that the refractive index of the SIL 52 is n and the wavelength of the laser beam in the air is λ, the wavelength of the laser beam in the SIL 52 is λ / n. Therefore, the spot diameter of the laser beam on the emission surface of the SIL 52 is 1 / n of the spot diameter collected by the objective lens 51.

When the laser beam emitted from the SIL 52 enters the air, it returns to the original spot diameter again. However, SIL5
In the range where the distance from the emission surface of No. 2 is up to １ ／ of the wavelength of the laser light (about 100 nm or less), that is, in the near-field region, the laser light seeps out with the same properties as in the SIL 52. The light leached in this way is called evanescent light. The spot diameter of the evanescent light is as small as 1 / n of the spot diameter collected by the objective lens 51. By using such evanescent light, it is possible to increase the areal recording density of the optical disc 500.

[0009]

In the near-field recording / reproducing optical disk apparatus shown in FIG. 16, a laser beam is focused on a signal recording surface 502 on the front side of an optical disk 500. Therefore, the optical disk device of FIG.
When the optical disk 400 for the conventional recording / reproducing method is used for recording and reproducing, a good light spot cannot be obtained on the signal recording surface 402 on the back side due to the spherical aberration caused by the thickness of the substrate 401.

Therefore, the optical disk device of the near-field recording / reproducing method shown in FIG. 16 cannot be used for recording and reproducing of the optical disk 400 of the conventional recording / reproducing method.

An object of the present invention is to provide an optical head and an optical disk apparatus capable of performing recording or reproduction on an optical disk having a signal recording surface formed on the back surface of a substrate and an optical disk having a signal recording surface formed on the front surface of the substrate. It is to provide.

[0012]

Means for Solving the Problems and Effects of the Invention The optical head according to the first invention has a first optical disk in which a signal recording surface is formed on the back side of a transparent substrate and a signal recording surface on the front side of the substrate. An optical head for selectively recording or reproducing data on or from a formed second optical disk, wherein the objective lens condenses light on a signal recording surface through a transparent substrate of the first optical disk during recording or reproduction of the first optical disk. And the second
And a solid immersion lens for irradiating near-field light to the signal recording surface of the second optical disc during recording or reproduction of the optical disc.

In the optical head according to the present invention, the first
During recording or reproduction of the optical disk, light is focused on the signal recording surface through the transparent substrate of the first optical disk by the objective lens. Further, at the time of recording or reproduction of the second optical disk, near-field light is irradiated on the signal recording surface of the second optical disk by the solid immersion lens.

Therefore, an optical head having compatibility with an optical disk having a signal recording surface formed on the back surface of the substrate and an optical disk having a signal recording surface formed on the front surface of the substrate is realized.

An optical head according to a second aspect of the present invention is selectively applicable to a first optical disk having a signal recording surface formed on the back surface of a transparent substrate and a second optical disk having a signal recording surface formed on the front surface of the substrate. An optical head for performing recording or reproduction on a first optical disc, an objective lens for condensing light on a signal recording surface through a transparent substrate of the first optical disc during recording or reproduction on a first optical disc, and recording or reproduction on a second optical disc A correction plate which is movably provided in an optical path between the objective lens and the second optical disk, and has optical characteristics equivalent to the transparent substrate of the first optical disk, and a correction plate when recording or reproducing the second optical disk. A light source that is movable in an optical path between the optical disk and the second optical disk, condenses the light transmitted through the objective lens and the correction plate, and irradiates the signal recording surface of the second optical disk with near-field light. It is obtained by a head immersion lens.

In the optical head according to the present invention, the first
At the time of recording or reproduction of the optical disk, light is focused on the signal recording surface through the transparent substrate of the first optical disk by the objective lens. Further, at the time of recording or reproduction of the second optical disc, the correction plate and the solid immersion lens move in the optical path between the objective lens and the second optical disc,
Light transmitted through the objective lens and the correction plate is condensed by the solid immersion lens, and near-field light is applied to the signal recording surface of the second optical disc.

In this case, since the correction plate has optical characteristics equivalent to the transparent substrate of the first optical disk, an effect equivalent to transmitting light through the transparent substrate of the first optical disk by transmitting light through the correction plate is obtained. can get. Thereby, the light is focused on the signal recording surface on the front side of the second optical disc by the objective lens and the solid immersion lens.

Thus, an optical head having compatibility with an optical disk having a signal recording surface formed on the back surface of the substrate and an optical disk having a signal recording surface formed on the front surface of the substrate is realized.

An optical head according to a third aspect of the present invention is selectively used for a first optical disk having a signal recording surface formed on the rear surface of a transparent substrate and a second optical disk having a signal recording surface formed on the front surface of the substrate. An optical head for performing recording or reproduction on a first optical disc, a first objective lens for condensing light on a signal recording surface through a transparent substrate of the first optical disc during recording or reproduction on the first optical disc; A solid immersion lens for irradiating near-field light to a signal recording surface of the second optical disc during recording or reproduction; and a second objective lens for guiding light to the solid immersion lens during recording or reproduction on the second optical disc. Things.

In the optical head according to the present invention, the first
At the time of recording or reproduction of the optical disc, light is focused on the signal recording surface through the transparent substrate of the first optical disc by the first objective lens. Further, at the time of recording or reproduction of the second optical disc, light is guided to the solid immersion lens by the second objective lens, and near-field light is applied to the signal recording surface of the second optical disc by the solid immersion lens.

In this manner, an optical head having compatibility with an optical disk having a signal recording surface formed on the back surface of the substrate and an optical disk having a signal recording surface formed on the front surface of the substrate is realized.

An optical head according to a fourth aspect of the present invention comprises: a first optical disk having a signal recording surface formed on a rear surface of a transparent substrate; a second optical disk having a signal recording surface formed on a front surface of the substrate; The third in which the signal recording surface is formed on the front side of the substrate
An optical head for selectively recording or reproducing data on or from an optical disk, an objective lens for condensing light on a signal recording surface through a transparent substrate of the first optical disk when recording or reproducing on the first optical disk; A first correction plate movably provided in an optical path between an objective lens and a second optical disc during recording or reproduction of the first optical disc and having optical characteristics equivalent to a transparent substrate of the first optical disc; Is provided movably in the optical path between the first correction plate and the second optical disk at the time of recording or reproduction of the optical disk, and condenses the light transmitted through the objective lens and the first correction plate to form the second optical disk. A solid immersion lens for irradiating near-field light to a signal recording surface of the optical disc; and a immersion lens movably provided in an optical path between the objective lens and the third optical disc during recording or reproduction of the third optical disc. A second correction plate having optical characteristics equivalent to that of the transparent substrate of the first optical disk, and movable in an optical path between the second correction plate and the third optical disk during recording or reproduction of the third optical disk And an aspherical lens for condensing the light transmitted through the objective lens and the second correction plate on the signal recording surface of the third optical disk.

In the optical head according to the present invention, the first
At the time of recording or reproduction of the optical disk, light is focused on the signal recording surface through the transparent substrate of the first optical disk by the objective lens.

When recording or reproducing data on or from the second optical disk, the first correction plate and the solid immersion lens move into the optical path between the objective lens and the second optical disk, and the objective lens and the first correction plate are moved. Is transmitted through the solid immersion lens, and the signal recording surface of the second optical disc is irradiated with near-field light.

In this case, since the first correction plate has optical characteristics equivalent to the transparent substrate of the first optical disk,
Thus, an effect equivalent to transmitting the light through the transparent substrate of the first optical disk can be obtained by transmitting the light through the correction plate. Thereby, the light is focused on the signal recording surface on the front side of the second optical disc by the objective lens and the solid immersion lens.

Further, at the time of recording or reproduction of the third optical disk, the second correction plate and the aspherical lens move into the optical path between the objective lens and the third optical disk, and the objective lens and the second correction plate Is transmitted to the signal recording surface of the third optical disc by the aspherical lens.

In this case, since the second correction plate has optical characteristics equivalent to the transparent substrate of the first optical disc,
Thus, an effect equivalent to transmitting the light through the transparent substrate of the first optical disk can be obtained by transmitting the light through the correction plate. Thereby, the light is focused on the signal recording surface on the front surface side of the third optical disc by the objective lens and the aspherical lens.

As described above, an optical head which is compatible with an optical disk having a signal recording surface formed on the back surface of the substrate and two types of optical disks having a signal recording surface formed on the front surface of the substrate is realized. .

An optical head according to a fifth aspect of the present invention comprises: a first optical disk having a signal recording surface formed on a rear surface of a transparent substrate; a second optical disk having a signal recording surface formed on a front surface of the substrate; The third in which the signal recording surface is formed on the front side of the substrate
An optical head for selectively recording or reproducing data on or from an optical disk, comprising: a first objective lens for condensing light on a signal recording surface through a transparent substrate of the first optical disk during recording or reproduction on the first optical disk; A solid immersion lens for irradiating near-field light to a signal recording surface of the second optical disc during recording or reproduction on the second optical disc; and a light irradiating lens on the signal recording face of the third optical disc during recording or reproduction on the third optical disc. And a second objective lens that guides light to a solid immersion lens or an aspherical lens during recording or reproduction of the second or third optical disk.

In the optical head according to the present invention, the first
At the time of recording or reproduction of the optical disc, light is focused on the signal recording surface through the transparent substrate of the first optical disc by the first objective lens. Further, at the time of recording or reproduction of the second optical disc, light is guided to the solid immersion lens by the second objective lens, and near-field light is applied to the signal recording surface of the second optical disc by the solid immersion lens. Further, at the time of recording or reproduction on the third optical disk, light is guided to the aspherical lens by the second objective lens, and the light is focused on the signal recording surface of the third optical disk by the aspherical lens.

As described above, an optical head which is compatible with an optical disk having a signal recording surface formed on the back surface of the substrate and two types of optical disks having a signal recording surface formed on the front surface of the substrate is realized. .

An optical head according to a sixth aspect is the optical head according to any one of the first to fifth aspects, wherein:
The solid immersion lens has a partially spherical entrance surface and a lower surface including a flat exit surface having a predetermined diameter at a central portion, and a lower surface around the exit surface is formed by a surface different from the exit surface. It is.

In this case, since the lower surface around the light exit surface of the solid immersion lens is formed on a surface different from the light exit surface, alignment of the optical axis of the solid immersion lens is easy when assembling the optical head.

[0034] The optical disc apparatus according to the seventh aspect of the present invention is selectively applicable to a first optical disc having a signal recording surface formed on the rear surface of a transparent substrate and a second optical disc having a signal recording surface formed on the front surface of the substrate. An optical disc device that performs recording or reproduction on a first optical disc, a light source that emits light, an objective lens that condenses light on a signal recording surface through a transparent substrate of the first optical disc during recording or reproduction of the first optical disc, A correction plate movably provided in an optical path between the objective lens and the second optical disk during recording or reproduction of the second optical disk and having optical characteristics equivalent to the transparent substrate of the first optical disk; Is provided movably in the optical path between the correction plate and the second optical disc during recording or reproduction of
A solid immersion lens for condensing light transmitted through the objective lens and the correction plate and irradiating near-field light to the signal recording surface of the second optical disc; a photodetector for detecting light; and light emitted from the light source And an optical system for guiding return light from the first or second optical disk that has passed through the objective lens to the photodetector.

In the optical disk device according to the present invention, at the time of recording or reproduction of the first optical disk, light emitted from the light source is guided to the objective lens by the optical system. And
Light is condensed on the signal recording surface through the transparent substrate of the first optical disc by the objective lens. The return light from the first optical disc passes through the objective lens and is guided to the photodetector by the optical system.

During recording or reproduction of the second optical disk, the correction plate and the solid immersion lens move in the optical path between the objective lens and the second optical disk. Light emitted from the light source is guided to the objective lens by the optical system. The light transmitted through the objective lens and the correction plate is condensed by a solid immersion lens, and the signal recording surface of the second optical disc is irradiated with near-field light. The return light from the second optical disk passes through the solid immersion lens, the correction plate, and the objective lens, and is guided to the photodetector by the optical system.

In this case, since the correction plate has optical characteristics equivalent to the transparent substrate of the first optical disk, an effect equivalent to transmitting light through the transparent substrate of the first optical disk by transmitting light through the correction plate is obtained. can get. Thereby, the light is focused on the signal recording surface on the front side of the second optical disc by the objective lens and the solid immersion lens.

In this way, it is possible to record or reproduce data on or from the optical disk having the signal recording surface formed on the back surface of the substrate and the optical disk having the signal recording surface formed on the front surface of the substrate.

The optical disc apparatus according to the eighth aspect of the present invention is selectively applicable to a first optical disc having a signal recording surface formed on the rear surface of a transparent substrate and a second optical disc having a signal recording surface formed on the front surface of the substrate. An optical disc device for performing recording or reproduction on a first optical disc, and a first objective lens for condensing light on a signal recording surface through a transparent substrate of the first optical disc during recording or reproduction of the first optical disc A solid immersion lens for irradiating near-field light to a signal recording surface of the second optical disc during recording or reproduction of the second optical disc, and a second immersion lens for guiding light to the solid immersion lens during recording or reproduction of the second optical disc. And an optical detector for detecting light, and guiding light emitted from a light source to the first objective lens during recording or reproduction of the first optical disc. The transmitted through the first objective lens 1
The light emitted from the light source was guided to the second objective lens and transmitted through the solid immersion lens and the second objective lens during recording or reproduction of the second optical disk. An optical system for guiding return light from the second optical disk to the photodetector.

In the optical disk device according to the present invention, at the time of recording or reproduction on the first optical disk, light emitted from the light source is guided to the first objective lens by the optical system. Then, light is focused on the signal recording surface through the transparent substrate of the first optical disc by the first objective lens. The return light from the first optical disc passes through the first objective lens and is guided to the photodetector by the optical system.

During recording or reproduction on the second optical disk, light emitted from the light source is guided to the second objective lens by the optical system. Then, light is guided to the solid immersion lens by the second objective lens, and near-field light is applied to the signal recording surface of the second optical disk by the solid immersion lens. The return light from the second optical disc passes through the solid immersion lens and the second objective lens, and is guided to the photodetector by the optical system.

In this manner, recording or reproduction can be performed on an optical disk having a signal recording surface formed on the back surface of the substrate and an optical disk having a signal recording surface formed on the front surface of the substrate.

An optical disc device according to a ninth aspect of the present invention comprises: a first optical disc having a signal recording surface formed on a rear surface of a transparent substrate; a second optical disc having a signal recording surface formed on a front surface of the substrate; An optical disk for selectively recording or reproducing data on or from a third optical disk having a signal recording surface formed on the front surface side of a substrate, comprising: a light source for emitting light; and a first optical disk for recording or reproducing on the first optical disk. An objective lens for condensing light on a signal recording surface through a transparent substrate of the optical disc, and a movable first optical disc provided in the optical path between the objective lens and the second optical disc during recording or reproduction of the second optical disc; A first correction plate having optical characteristics equivalent to that of a transparent substrate of an optical disc;
Is provided movably in the optical path between the correction plate and the second optical disk, condenses the light transmitted through the objective lens and the first correction plate, and generates a near-field light on the signal recording surface of the second optical disk. A solid immersion lens for irradiating light, and an optical characteristic equivalent to that of a transparent substrate of the first optical disc, which is movable in an optical path between the objective lens and the third optical disc during recording or reproduction of the third optical disc. A second correction plate having an objective lens and a second correction plate that are movable in an optical path between the second correction plate and the third optical disk during recording or reproduction of the third optical disk. An aspherical lens for condensing the transmitted light on the signal recording surface of the third optical disc, a photodetector for detecting the light, and first and second light transmitting the objective lens while guiding the light emitted from the light source to the objective lens. 2nd or 3rd It is obtained by an optical system for guiding the returned light from the optical disk to the photodetector.

In the optical disk device according to the present invention, at the time of recording or reproduction on the first optical disk, light emitted from the light source is guided to the objective lens by the optical system. Then, light is focused on the signal recording surface through the transparent substrate of the first optical disk by the objective lens. The return light from the first optical disc passes through the objective lens and is guided to the photodetector by the optical system.

During recording or reproduction on the second optical disk, the first correction plate and the solid immersion lens move in the optical path between the objective lens and the second optical disk. Light emitted from the light source is guided to the objective lens by the optical system. Light transmitted through the objective lens and the first correction plate is condensed by a solid immersion lens, and near-field light is applied to the signal recording surface of the second optical disc. The return light from the second optical disc passes through the solid immersion lens, the first correction plate, and the objective lens, and is guided to the photodetector by the optical system.

In this case, since the first correction plate has optical characteristics that are transparent to the transparent substrate of the first optical disk,
By passing through the correction plate, an effect equivalent to transmitting through the transparent substrate of the first optical disk can be obtained. Thereby, the light is focused on the signal recording surface on the front side of the second optical disc by the objective lens and the solid immersion lens.

Further, at the time of recording or reproduction of the third optical disk, the second correction plate and the aspherical lens move in the optical path between the objective lens and the third optical disk. Light emitted from the light source is guided to the objective lens by the optical system. The light transmitted through the objective lens and the second correction plate is
The light is focused on the signal recording surface of the third optical disk by the aspheric lens. The return light from the third optical disc passes through the aspheric lens, the second correction plate, and the objective lens, and is guided to the photodetector by the optical system.

In this case, since the second correction plate has optical characteristics equivalent to the transparent substrate of the first optical disk,
By passing through the correction plate, an effect equivalent to transmitting through the transparent substrate of the first optical disk can be obtained. Thereby, the light is focused on the signal recording surface on the front surface side of the third optical disc by the objective lens and the aspherical lens.

In this manner, it is possible to record or reproduce data on or from an optical disc having a signal recording surface formed on the back surface of the substrate and two types of optical disc having a signal recording surface formed on the front surface of the substrate.

An optical disc device according to a tenth aspect of the present invention comprises: a first optical disc having a signal recording surface formed on the rear surface of a transparent substrate; a second optical disc having a signal recording surface formed on the front surface of the substrate; An optical disk device for selectively recording or reproducing data on or from a third optical disk having a signal recording surface formed on the front surface side of a substrate, comprising: a light source for emitting light; A first objective lens for condensing light on a signal recording surface through a transparent substrate of an optical disk, and a solid immersion lens for irradiating near-field light to a signal recording surface of the second optical disk during recording or reproduction of the second optical disk An aspherical lens for condensing light on the signal recording surface of the third optical disc during recording or reproduction on the third optical disc; and a solid lens for recording or reproducing on the second or third optical disc. A second objective lens for guiding light to a immersion lens or an aspherical lens, a photodetector for detecting light, and light emitted from a light source during recording or reproduction of the first optical disk, to the first objective lens. The light emitted from the light source is guided to the second objective lens at the time of recording or reproduction of the second optical disk, while guiding the return light from the first optical disk that has passed through the first objective lens while guiding the light. The return light from the second optical disc that has passed through the solid immersion lens and the second objective lens is guided to the photodetector, and the light emitted from the light source is applied to the second objective lens during recording or reproduction on the third optical disc. And an optical system for guiding return light from the third optical disk that has passed through the aspherical lens and the second objective lens to the photodetector.

In the optical disk device according to the present invention, at the time of recording or reproduction of the first optical disk, light emitted from the light source is guided to the first objective lens by the optical system. Then, light is focused on the signal recording surface through the transparent substrate of the first optical disc by the first objective lens. The return light from the first optical disc passes through the first objective lens and is guided to the photodetector by the optical system.

When recording or reproducing data on or from the second optical disk, light emitted from the light source is guided to the second objective lens by the optical system. Then, light is guided to the solid immersion lens by the second objective lens, and near-field light is applied to the signal recording surface of the second optical disk by the solid immersion lens. The return light from the second optical disc passes through the solid immersion lens and the second objective lens, and is guided to the photodetector by the optical system.

Further, at the time of recording or reproduction on the third optical disk, the light emitted from the light source is guided to the second objective lens by the optical system. Then, light is guided to the aspherical lens by the second objective lens, and the light is guided to the third by the aspherical lens.
Light is focused on the signal recording surface of the optical disk. The return light from the third optical disc passes through the aspheric lens and the second objective lens, and is guided to the photodetector by the optical system.

In this way, it is possible to record or reproduce data on or from an optical disk having a signal recording surface formed on the back surface of the substrate and two types of optical disk having a signal recording surface formed on the front surface of the substrate.

An optical disk device according to an eleventh aspect of the present invention is the optical disk device according to the tenth aspect, wherein the optical system is configured to perform recording or reproduction of the first optical disk and recording or reproduction of the second or third optical disk. It includes a first optical element that switches the polarization direction of light at different times, and a second optical element that switches the traveling direction of light in accordance with the polarization direction of light transmitted through the first optical element.

In this case, the polarization direction of the light is switched by the first optical element between the time of recording or reproduction of the first optical disk and the time of recording or reproduction of the second or third optical disk. Then, the traveling direction of the light is switched by the second optical element according to the polarization direction of the light transmitted through the first optical element.

Therefore, it is possible to easily switch between recording or reproducing of the first optical disk and recording or reproducing of the second or third optical disk.

The optical disc apparatus according to the twelfth aspect is a reflection type first optical disc having a signal recording surface formed on the back side of a transparent substrate.
An optical disc apparatus for selectively recording or reproducing data on or from a transmission-type second optical disc having a signal recording surface formed on the front side of an optical disc and a substrate, comprising: a light source for emitting light; Alternatively, an objective lens that condenses light on a signal recording surface through a transparent substrate of the first optical disc during reproduction and a movable optical path between the objective lens and the second optical disc during recording or reproduction of the second optical disc. A correction plate having an optical characteristic equivalent to that of the transparent substrate of the first optical disc; and a movable plate in a light path between the correction plate and the second optical disc during recording or reproduction of the second optical disc; A solid immersion lens that condenses light transmitted through the objective lens and the correction plate and emits near-field light to a signal recording surface of the second optical disc; A first photodetector for detecting reflected light of the first optical disc, a second photodetector for detecting transmitted light of the signal recording surface of the second optical disc, and a light emitted from the light source during recording or reproduction of the first optical disc. And the reflected light from the first optical disc that has passed through the objective lens is guided to the first photodetector, and the light emitted from the light source during recording or reproduction of the second optical disc is used as the objective lens. And an optical system for guiding the light.

In the optical disk device according to the present invention, at the time of recording or reproduction on the first optical disk, light emitted from the light source is guided to the objective lens by the optical system. And
Light is condensed on the signal recording surface through the transparent substrate of the first optical disc by the objective lens. The reflected light from the first optical disk passes through the objective lens and is guided to the first photodetector by the optical system.

During recording or reproduction of the second optical disk, the correction plate and the solid immersion lens move in the optical path between the objective lens and the second optical disk. Light emitted from the light source is guided to the objective lens by the optical system. The light transmitted through the objective lens and the correction plate is condensed by a solid immersion lens, and the signal recording surface of the second optical disc is irradiated with near-field light. The transmitted light from the second optical disc is guided to a second photodetector.

In this case, since the correction plate has optical characteristics equivalent to the transparent substrate of the first optical disk, an effect equivalent to transmitting light through the transparent substrate of the first optical disk by transmitting light through the correction plate is obtained. can get. Thereby, the light is focused on the signal recording surface on the front side of the second optical disc by the objective lens and the solid immersion lens.

In this manner, recording or reproduction can be performed on a reflective optical disk having a signal recording surface formed on the back surface of the substrate and a transmission type optical disk having a signal recording surface formed on the front surface of the substrate. Becomes

An optical disc device according to a thirteenth aspect of the present invention is directed to a reflection type first optical disc having a signal recording surface formed on the back side of a transparent substrate.
An optical disc apparatus for selectively recording or reproducing data on or from a transmission-type second optical disc having a signal recording surface formed on the front side of an optical disc and a substrate, comprising: a light source for emitting light; Alternatively, a first objective lens for condensing light on a signal recording surface through a transparent substrate of the first optical disc during reproduction, and near-field light on a signal recording surface of the second optical disc during recording or reproduction of the second optical disc. A solid immersion lens that emits light, a second objective lens that guides light to the solid immersion lens during recording or reproduction of a second optical disc, and a first photodetector that detects reflected light from a signal recording surface of the first optical disc A second photodetector for detecting light transmitted through a signal recording surface of the second optical disc; and a first light detector for recording or reproducing light from the light source during recording or reproduction on the first optical disc. And guides to the objective lens, the first
An optical system that guides reflected light from a first optical disc that has passed through an objective lens to a first photodetector, and guides light emitted from a light source to a second objective lens during recording or reproduction of a second optical disc. It is provided with.

In the optical disk device according to the present invention, at the time of recording or reproduction on the first optical disk, light emitted from the light source is guided to the first objective lens by the optical system. Then, the light is focused on the signal recording surface through the transparent substrate of the first optical disc by the first objective lens. The reflected light from the first optical disc passes through the first objective lens and is guided by the optical system to the first photodetector.

During recording or reproduction on the second optical disk, light emitted from the light source is guided to the second objective lens by the optical system. Then, light is guided to the solid immersion lens by the second objective lens, and near-field light is irradiated to the signal recording surface of the second optical disk by the solid immersion lens. The transmitted light from the second optical disc is guided to a second photodetector.

In this manner, it is possible to perform recording or reproduction on a reflection type optical disc having a signal recording surface formed on the back surface of the substrate and a transmission type optical disc having a signal recording surface formed on the front surface side of the substrate. Becomes

[0067]

1 and 2 are schematic views showing the structure of an optical disk device according to a first embodiment of the present invention.

In the following description, a conventional optical disk for a recording / reproducing system such as a DVD is called a low-density optical disk, and an optical disk for a near-field recording / reproducing system is called a high-density optical disk.

FIG. 1 shows the recording or reproduction of the high-density optical disc 100, and FIG. 2 shows the recording or reproduction of the low-density optical disc 200.

As shown in FIG.
0, the signal recording surface 102
Are formed. On the other hand, as shown in FIG. 2, in the low-density optical disk 200, a signal recording surface 202 is formed on the back surface of a transparent substrate 201.

In FIGS. 1 and 2, the optical head 1
Includes an objective lens 2 and an optical unit 3. The optical unit 3 includes a support 4, a correction plate 5, and a hemispherical SI.
L (solid immersion lens) 6. The flat lower surface of the SIL 6 becomes a laser light emission surface.
The correction plate 5 is attached to the upper part of the support 4, and the SIL 6 is attached to the lower part of the support 4.

The optical unit 3 is attached to one end of an arm 7 extending in the horizontal direction. A coil 8 is wound around the outer peripheral surface of the other end of the arm 7. A magnet 9 is arranged around the coil 8 of the arm 7. The arm 7 is supported movably in the direction of arrow X.

By switching the direction of the current flowing through the coil 8, the optical unit 3 attached to the arm 7 is moved to a position below the objective lens 2 and a position deviated from below the objective lens 2 by the magnetic force of the coil 8 and the magnet 9. Can be moved.

At the time of recording or reproduction on the high-density optical disc 100, the optical unit 3 moves to a position below the objective lens 2 as shown in FIG. The linearly polarized laser light emitted from the semiconductor laser element 11 is converted into parallel light by the collimator lens 12, and is converted into a parallel light.
4 is incident. As a result, the laser light is reflected by the polarizing beam splitter 14 in the direction of the objective lens 2, and
The laser light is converted into clockwise or counterclockwise circularly polarized laser light by the wave plate 15 and enters the objective lens 2. Laser light is
The high-density optical disk 100 is narrowed down by the objective lens 2, transmitted through the correction plate 5 of the optical unit 3, and transmitted by the SIL 6.
Is focused on the signal recording surface 102.

At the time of reproduction of the high-density optical disk 100, return light (reflected light) from the signal recording surface 102 of the high-density optical disk 100 passes through the SIL 6, the correction plate 5 and the objective lens 2, and is incident by the 波長 wavelength plate 15. Laser light at the time and 9
It is converted to linearly polarized laser light with a different 0 ° polarization direction,
The light passes through the polarizing beam splitter 14. The laser light transmitted through the polarizing beam splitter 14 is condensed on a light receiving surface of a photo sensor 17 by a condenser lens 16.

As shown in FIG. 2, the low-density optical disk 20
When recording or reproducing 0, the optical unit 3 moves to a position deviated from below the objective lens 2. The linearly polarized laser light emitted from the semiconductor laser element 11 is converted into parallel light by the collimator lens 12 and enters the polarization beam splitter 14. As a result, the laser light is reflected in the direction of the objective lens 2 by the polarization beam splitter 14, is converted into a clockwise or counterclockwise circularly polarized laser light by the quarter-wave plate 15, and the low-density optical disk 200 is converted by the objective lens 2. Of the signal recording surface 20
It is condensed on 2.

At the time of reproduction of the low-density optical disk 200, the feedback light (reflected light) from the signal recording surface 202 of the low-density optical disk 200 passes through the objective lens 2 and
Is converted into a linearly polarized laser beam having a 90 ° polarization direction different from that of the incident laser beam by the polarization beam splitter 14.
Through. The laser light transmitted through the polarizing beam splitter 14 is condensed on a light receiving surface of a photo sensor 17 by a condenser lens 16.

FIG. 3A is a schematic diagram showing the optical head 1 during recording or reproduction on the high-density optical disk 100, and FIG. 3B is a schematic diagram showing the optical head 1 during recording or reproduction on the low-density optical disk 200. It is.

As the semiconductor laser device 11 shown in FIGS. 1 and 2, for example, a semiconductor laser device that emits laser light having a wavelength of 650 nm is used.

As shown in FIG. 3B, the objective lens 2
Is designed for recording and reproduction of the low-density optical disc 200. That is, the objective lens 2 has a thickness (0.6 m in this embodiment) of the substrate 201 of the low-density optical disc 200.
m) is an aspherical lens having a lens shape determined in consideration of the spherical aberration generated by (m).

Thus, the laser beam can be focused by the objective lens 2 on the signal recording surface 201 on the back side through the substrate 201 of the low-density optical disk 200. The numerical aperture NA of the objective lens 2 is 0.6. In this case, the spot diameter of the laser beam formed on the signal recording surface 202 of the low-density optical disk 200 by the objective lens 2 is about 0.9 μm.
m.

In FIG. 3A, the correction plate 5 of the optical unit 3 has optical characteristics equivalent to the substrate 201 of the low-density optical disk 200. In this embodiment, the correction plate 5 has the same refractive index as the substrate 201 and the same thickness of 0.6 mm.
Having. The correction plate 5 acts so that the laser beam narrowed down by the objective lens 2 is focused on the center of the emission surface of the SIL 6.

The surface of the high-density optical disk 100 is SIL6
The distance d between the surface of the high-density optical disc 100 and the surface of the high-density optical disc 100 is
When the distance is less than m, the evanescent light oozing out from the exit surface of the SIL 6 can be used.

That is, the numerical aperture NA at the converging point of the SIL 6 is applied to the surface of the high-density optical disc 100 as it is. For example, when the SIL 6 is formed of a material having a refractive index of 1.8, the numerical aperture NA is 1.08. In this case, the spot diameter of the laser beam formed on the surface of the high-density optical disc 100 by the SIL 6 is about 0.5 μm.

In the optical disk device of this embodiment, by moving the optical unit 3 of the optical head 1,
High density optical disc 100 and low density optical disc 200
Recording or reproduction can be performed.

In the optical head 1 of the above-described embodiment, the objective lens 2 is not the lower surface of the SIL 6 but the SIL 6
By switching to an objective lens that focuses on the signal recording surface 102 of the optical disc 100 via the optical disc 100, the beam spot diameter can be reduced and the signal can be reproduced.

FIGS. 4 and 5 are schematic diagrams showing the configuration of an optical disk device according to the second embodiment of the present invention.

FIG. 4 shows the recording or reproduction of the high-density optical disc 100, and FIG. 5 shows the recording or reproduction of the low-density optical disc 200.

As shown in FIGS. 4 and 5, the optical disk device has an optical head 21. The optical head 21
An objective lens 22 for the high-density optical disc 100, a hemispherical SIL 23, and an objective lens 24 for the low-density optical disc 200 are provided.

As shown in FIG.
When recording or reproducing 0, the linearly polarized laser light emitted from the semiconductor laser element 25 is
The light is converted into a parallel light by the light source 6. By not applying a voltage to the liquid crystal 27, the polarization direction of the linearly polarized laser light becomes 90 degrees.
° rotate. As a result, the laser light is reflected by the polarizing beam splitter 28 in the direction of the objective lens 22. The laser light reflected by the polarization beam splitter 28 is 1
The laser light is converted into clockwise or counterclockwise circularly polarized laser light by the 波長 wavelength plate 29, and is focused on the signal recording surface 102 of the high density optical disc 100 by the objective lens 22 and the SIL 23.

At the time of reproduction of the high-density optical disk 100, the laser light is reflected by the signal recording surface 102 of the high-density optical disk 100, and becomes circularly polarized light in the opposite direction to that at the time of incidence.
The laser beam passes through the SIL 23 and the objective lens 22 and is converted by the 波長 wavelength plate 29 into linearly polarized laser light having a 90 ° polarization direction different from that of the incident laser light. The laser light passes through the polarization beam splitter 28 and is condensed on the light receiving surface of the photo sensor 31 by the condenser lens 30.

As shown in FIG. 5, the low-density optical disk 20
When recording or reproducing 0, the linearly polarized laser light emitted from the semiconductor laser element 25 is
The light is converted into a parallel light by the light source 6. In this case, by applying a voltage to the liquid crystal 27, the polarization direction of the linearly polarized laser light does not rotate by 90 °. As a result, the laser beam transmitted through the liquid crystal 27 passes through the polarization beam splitter 28 and
The light is converted into clockwise or counterclockwise circularly polarized laser light by the wave plate 32, and is reflected by the mirror 33 in the direction of the objective lens 24. The laser light reflected by the mirror 33 is transmitted through the substrate 201 of the low-density optical disc 200 by the objective lens 24 and collected on the signal recording surface 202.

At the time of reproduction of the low-density optical disk 200, the laser light is reflected by the signal recording surface 202 of the low-density optical disk 200, and becomes circularly polarized light in the opposite direction to that at the time of incidence.
The light passes through the objective lens 24 and is reflected by the mirror 33 in the direction of the polarization beam splitter 28. The laser light reflected by the mirror 33 is converted into linearly-polarized laser light having a 90 ° polarization direction different from that of the incident laser light by the quarter-wave plate 32, and is converted by the polarization beam splitter 28 toward the condenser lens 30. Is reflected. Polarizing beam splitter 2
The laser beam reflected by 8 is condensed on the light receiving surface of photosensor 31 by condensing lens 30.

In the optical disk device of this embodiment, the optical head 21 includes the objective lens 22 and the SIL 23 for the high-density optical disk 100 and the objective lens 24 for the low-density optical disk 200. Both recording and playback can be performed.

Note that another optical element such as a Pockels cell or a Faraday element may be used instead of the liquid crystal 27 in FIGS.

FIG. 6 is a diagram showing the function of the Pockels cell. When a voltage V is applied between the electrodes 61 and 62 of the Pockels cell 60, the laser light 6 incident on the Pockels cell 60
3 can be rotated. Further, by adjusting the applied voltage V, the rotation angle of the polarization plane of the laser beam 63 can be changed. The Pockels cell 60 is easy to assemble and adjust.

In the optical disk device of the second embodiment, the voltage V is selectively applied so that the polarization plane of the laser beam 63 rotates 90 degrees.

FIG. 7 shows the function of the Faraday element. When the magnetic field H is applied in a direction parallel to the direction of the laser light 71 passing through the Faraday element 70, the polarization plane of the laser light 71 can be rotated. Therefore, by winding the coil around the lens barrel supporting the Faraday element 70, the polarization plane of the laser light 71 can be rotated. This Faraday element 70 is also easy to assemble and adjust.

FIG. 8 is a schematic diagram showing the configuration of an optical disk device according to the third embodiment of the present invention.

In the optical disk device shown in FIG. 8, the optical head 161 further includes an aspheric lens 166 in addition to the SIL 167. In such an optical disk device,
A high-density optical disk 300 is formed by a compound lens recording / reproducing method using an objective lens 162 and an aspherical lens 166.
Can be recorded or reproduced, and the objective lens 1
The near-field recording / reproducing method using the SIL 62 and the SIL 167 enables recording or reproduction on the high-density optical disc 100. Further, recording or reproduction of the low-density optical disk 200 can be performed by a conventional recording and reproduction method using the objective lens 162.

In FIG. 8, an optical head 161 includes an objective lens 162 and an optical unit 163. The optical unit 163 includes an aspheric lens 166 and a hemispherical SI.
L167, a support 164, and two correction plates 165. Two correction plates 16 are provided on the support 164.
5 is attached, and an aspheric lens 166 and an SIL 167 are attached to a lower portion of the support 164, respectively. The distance between the flat exit surface of the aspheric lens 166 and the surface of the high density optical disc 300 is equal to the distance between the exit surface of the SIL 167 and the surface of the high density optical disc 300.
It is within the near field area of 00 nm or less.

The optical unit 163 is attached to one end of an arm 170 extending in the horizontal direction. Arm 17
A coil 168 is wound around the outer peripheral surface at the other end of the zero.
A magnet 169 is arranged around the coil 168 of the arm 170. The arm 170 is supported movably in the direction of arrow X.

By switching the direction of the current flowing through the coil 168, the magnetic force of the coil 168 and the magnet 169 causes the optical unit 163 attached to the arm 170 to move.
Can be moved to a position below the objective lens 162, and the optical unit 163 can be moved to a position deviated from below the objective lens 162.

The surface recording density of the high-density optical disc 300 for recording or reproducing by the composite lens recording / reproducing method is as follows.
It is lower than that of the high-density optical disc 100 that performs recording or reproduction by the near-field recording / reproduction method. Therefore, recording or reproduction of the high-density optical disk 300 is performed not by evanescent light but by laser light having a small spot diameter focused on the signal recording surface 302 by the objective lens 162 and the aspherical lens 166.

FIG. 8 shows the recording or reproduction of the high-density optical disk 300 by the composite lens recording / reproducing method.

At the time of recording or reproduction of the high-density optical disk 300 by the composite lens system recording / reproduction method, the arm 170 is moved so that the aspherical lens 166 of the optical unit 163 is located below the objective lens 162 as shown in FIG. Moving. The linearly polarized laser light emitted from the semiconductor laser element 171 is converted into parallel light by the collimator lens 172 and is incident on the polarization beam splitter 174. As a result, the laser beam is polarized by the polarization beam splitter 174.
Is reflected in the direction of the objective lens 162, is converted into clockwise or counterclockwise circularly polarized laser light by the 波長 wavelength plate 175, and enters the objective lens 162. The laser light is narrowed down by the objective lens 162, passes through the correction plate 165 of the optical unit 163, and enters the aspheric lens 166. The laser light is focused on the signal recording surface 302 of the high-density optical disk 300 by the aspheric lens 166.

At the time of reproduction of the high-density optical disk 300, the feedback light from the signal recording surface 302 of the high-density optical disk 300 passes through the aspheric lens 166, the correction plate 165, and the objective lens 162, and is incident by the quarter wavelength plate 175. Is converted into linearly polarized laser light having a 90 ° polarization direction different from that of the laser beam, and transmits through the polarization beam splitter 174. The laser light transmitted through the polarization beam splitter 174 is condensed on the light receiving surface of the photo sensor 177 by the condenser lens 176.

At the time of recording or reproduction of the high-density optical disk 100 by the near-field recording / reproduction method, recording or reproduction of the high-density optical disk 100 is performed as follows, as in the optical disk apparatus of FIG.

The arm 170 moves so that the SIL 167 of the optical unit 163 is located below the objective lens 162. The linearly polarized laser light emitted from the semiconductor laser element 171 is converted into parallel light by the collimator lens 172 and is incident on the polarization beam splitter 174. As a result, the laser beam is polarized by the polarization beam splitter 174.
Is reflected in the direction of the objective lens 162, is converted into clockwise or counterclockwise laser light by the 波長 wavelength plate 175, and is incident on the objective lens 162. The laser beam is narrowed down by the objective lens 162, passes through the correction plate 165 of the optical unit 163, and enters the SIL 167. SIL
The laser light is focused on the emission surface of the optical disk 167, and the evanescent light is applied to the signal recording surface 102 of the high-density optical disk 100.

At the time of reproduction of the high-density optical disc 100, the feedback light from the signal recording surface 102 of the high-density optical disc 100 is transmitted by the SIL 167, the correction plate 165, and the objective lens 162.
The laser beam is converted by the レ ー ザ wavelength plate 175 into linearly polarized laser light having a 90 ° polarization direction different from that of the incident laser light, and is transmitted through the polarization beam splitter 174. The laser light transmitted through the polarization beam splitter 174 is condensed on the light receiving surface of the photo sensor 177 by the condenser lens 176.

At the time of recording or reproduction of the low-density optical disk 200 according to the conventional recording / reproducing method, recording or reproduction of the low-density optical disk 200 is performed as follows, as in the optical disk apparatus of FIG.

The arm 170 moves so that the optical unit 163 comes to a position deviated from below the objective lens 162. The linearly polarized laser light emitted from the semiconductor laser element 171 is converted into parallel light by the collimator lens 172 and is incident on the polarization beam splitter 174. As a result, the laser beam is reflected by the polarizing beam splitter 174 in the direction of the objective lens 162, and the quarter-wave plate 175
Is converted into a clockwise or counterclockwise circularly polarized laser beam, and is transmitted through the transparent substrate 201 of the low-density optical disc 200 by the objective lens 162 and collected on the signal recording surface 202.

At the time of reproduction of the low-density optical disk 200, the feedback light from the signal recording surface 202 of the low-density optical disk 200 passes through the objective lens 162, and the quarter-wave plate 175 causes the laser beam at the time of incidence to have a 90 ° polarization direction. The laser light is converted into laser light having a different linear polarization, and passes through the polarization beam splitter 174. The laser light transmitted through the polarization beam splitter 174 is condensed on the light receiving surface of the photo sensor 177 by the condenser lens 176.

As the semiconductor laser device 171 shown in FIG.
For example, a semiconductor laser device that emits laser light having a wavelength of 650 nm is used.

As the objective lens 162, a lens having a curvature of the first aspherical surface 162a of 0.48, a curvature of the second aspherical surface 162b of -0.10, and a numerical aperture NA of 0.6 is used. When the curvature has a positive value, it means that the surface of the lens is convex with respect to the incident light. When the curvature has a negative value, the lens surface has a concave shape with respect to the incident light. It means that it has become. In the conventional recording / reproducing method, the spot diameter of the laser light focused on the signal recording surface 202 of the low-density optical disk 200 by such an objective lens 162 is about 0.9 μm.

The structure and function of the correction plate 165 and SIL 167 are the same as those of the correction plate 5 and SIL 6 of FIG. For example, in the near-field recording / reproducing method, when the SIL 167 formed of a material having a refractive index of 1.8 and the objective lens 162 are combined, the numerical aperture NA is 1.
08. In this case, the spot diameter of the evanescent light formed on the signal recording surface 102 of the high density optical disc 100 is about 0.5 μm.

The aspheric lens 166 has a flat exit surface and an entrance surface having a curvature of 0.25. The laser light narrowed down to the aspherical lens 166 by the objective lens 162 is transmitted to the signal recording surface 30 of the high-density optical disk 300.
It is condensed on 2. In the compound lens system recording / reproducing method,
When the aspherical lens 166 and the objective lens 162 formed of a material having a refractive index of 1.8 are combined, the numerical aperture NA is 0.8. In this case, the spot diameter of the laser light formed on the signal recording surface 302 of the high-density optical disk 300 is about 0.7 μm. The shape of the aspherical lens is not limited to the aspherical lens 166 shown in FIG. Any material can be used as long as it has a flat emission surface and can collect laser light on the signal recording surface 302 of the high-density optical disk 300.

In the optical disk device of the present embodiment, the optical head 161 includes the objective lens 162, the aspherical lens, and the SI.
Since the optical head 161 includes the L167, by moving the optical unit 163 of the optical head 161, it becomes possible to perform recording or reproduction on an optical disc having a different surface recording density.
That is, the high density optical disc 10
0 is recorded or reproduced, and the aspherical lens 16
6, the recording or reproduction of the high-density optical disk 300 is performed, and further, the recording or reproduction of the low-density optical disk 200 is performed using the objective lens 162.

FIG. 9 is a schematic diagram showing the configuration of an optical disk device according to the fourth embodiment of the present invention.

In the optical disk device shown in FIG. 9, similarly to the optical disk device shown in FIG. 8, the recording or reproduction of the high-density optical disk 300 is possible by the compound lens recording / reproducing method using the objective lens 182 and the aspherical lens 183. Yes,
The near-field recording / reproducing method using the objective lens 182 and the SIL 184 enables recording / reproducing of the high-density optical disc 100, and the recording / reproducing of the low-density optical disc 200 by the conventional recording / reproducing method using the objective lens 185. Is possible. As described above with reference to FIG. 8, the high-density optical disk 300 has a lower areal recording density than the high-density optical disk 100.

As shown in FIG. 9, the optical disk device includes an optical head 181. The optical head 181 includes an objective lens 182 for a high-density optical disk, an aspherical lens 183,
A hemispherical SIL 184 and a low-density optical disk objective lens 185 are provided. The aspheric lens 183 and the SIL 184 of the optical head 181 are supported by a support 198, respectively.
The support 198 is attached to one end of a horizontally extending arm 197.
A coil 195 is wound around the outer peripheral surface at the other end of the arm 197. A magnet 196 is arranged around the coil 195 of the arm 197. The arm 197 is supported movably in the direction of arrow X.

By switching the direction of the current flowing through the coil 195, the magnetic force of the coil 195 and the magnet 196 allows the aspheric lens 183 attached to the arm 197 to be rotated.
Alternatively, the SIL 184 can be moved to a position below the objective lens 182.

FIG. 9 shows the recording or reproduction of the high-density optical disk 300 by the composite lens recording / reproducing method.

At the time of recording or reproduction on the high-density optical disk 300 by the composite lens system recording / reproducing method, the aspherical lens 183 is positioned below the objective lens 182 so as to be positioned below.
The arm 197 moves. The linearly polarized laser light emitted from the semiconductor laser element 186 is collimated by the collimator lens 18.
7 is converted into parallel light. By not applying a voltage to the liquid crystal 188, the polarization direction of the linearly polarized laser light becomes 9
Rotate 0 °. As a result, the laser beam is reflected by the polarizing beam splitter 189 in the direction of the objective lens 182. The laser beam reflected by the polarization beam splitter 189 is converted into a clockwise or counterclockwise circularly polarized laser beam by the quarter wavelength plate 190, and the signal is recorded on the high-density optical disk 300 by the objective lens 182 and the aspheric lens 183. The light is focused on the surface 302.

At the time of reproduction of the high-density optical disk 300, the laser light is reflected by the signal recording surface 302 of the high-density optical disk 300, and becomes circularly polarized light in the direction opposite to that at the time of incidence.
Transmitted through the aspheric lens 183 and the objective lens 182,
The quarter-wave plate 190 converts the laser beam into linearly-polarized laser light having a 90 ° polarization direction different from that of the incident laser light. The laser light passes through the polarization beam splitter 189 and is condensed on the light receiving surface of the photo sensor 192 by the condenser lens 191.

At the time of recording or reproduction of the high-density optical disk 100 by the near-field recording / reproduction method, recording or reproduction of the high-density optical disk 100 is performed as follows, as in the optical disk apparatus of FIG.

The arm 197 moves so that the SIL 184 is located below the objective lens 182. The linearly polarized laser light emitted from the semiconductor laser element 186 is converted into parallel light by the collimator lens 187. By not applying a voltage to the liquid crystal 188, the polarization direction of the linearly polarized laser light is rotated by 90 °. As a result, the laser beam is split by the polarizing beam splitter 189 into the objective lens 182.
Is reflected in the direction of The laser light reflected by the polarization beam splitter 189 is converted into clockwise or counterclockwise circularly polarized laser light by the quarter-wave plate 190, and enters the objective lens 182 and the SIL 184. SIL1
The laser light is condensed on the emission surface 84, and the evanescent light is applied to the signal recording surface 102 of the high-density optical disc 100.

At the time of reproduction of the high-density optical disk 100, the laser light is reflected by the signal recording surface 102 of the high-density optical disk 100, and becomes circularly polarized light in the direction opposite to that at the time of incidence.
It passes through the SIL 184 and the objective lens 182 and
The wave plate 190 converts the laser light into a linearly polarized laser light having a 90 ° polarization direction different from that of the incident laser light. The laser light passes through the polarizing beam splitter 189 and is condensed on the light receiving surface of the photo sensor 192 by the condenser lens 191.

At the time of recording or reproduction of the low-density optical disk 200 according to the conventional recording / reproducing method, recording or reproduction of the low-density optical disk 200 is performed as follows, as in the optical disk apparatus of FIG.

The linearly polarized laser light emitted from the semiconductor laser element 186 is converted by the collimator lens 187 into parallel light. In this case, by applying a voltage to the liquid crystal 188, the polarization direction of the linearly polarized laser light becomes 90 degrees.
° does not rotate. As a result, the laser light transmitted through the liquid crystal 188 is transmitted through the polarization beam splitter 189, is converted into clockwise or counterclockwise circularly polarized laser light by the quarter-wave plate 193, and is converted by the mirror 194 toward the objective lens 185. Is reflected. The laser light reflected by the mirror 194 is transmitted to the low-density optical disk 200 by the objective lens 185.
Through the transparent substrate 201 and is focused on the signal recording surface 202.

At the time of reproduction of the low-density optical disk 200, the laser light is reflected by the signal recording surface 202 of the low-density optical disk 200, and becomes circularly polarized light in the opposite direction to that at the time of incidence.
The light passes through the objective lens 185 and is reflected by the mirror 194 in the direction of the polarization beam splitter 189. Mirror 19
The laser light reflected by the laser beam 4 is converted by a quarter-wave plate 190 into linearly polarized laser light having a polarization direction different from that of the incident laser light by 90 °.
Is reflected in the direction of the condenser lens 191. The laser beam reflected by the polarization beam splitter 189 is condensed on the light receiving surface of the photo sensor 192 by the condenser lens 191.

The configuration and function of the liquid crystal 188 shown in FIG. 9 are the same as those of the liquid crystal 27 shown in FIGS. Further, the objective lens 182, the aspherical lens 183, and the SIL 18
The configuration and function of No. 4 are the same as those of the objective lens 162, the aspheric lens 166, and the SIL 167 of FIG.

In the optical disk device of this embodiment, the optical head 181 has the objective lens 182, aspheric lens 183, and SIL 184 for a high-density optical disk, and the objective lens 185 for a low-density optical disk. It becomes possible to perform recording or reproduction on different optical disks. That is, the recording or reproduction of the high-density optical disc 100 is performed using the SIL 184, and the high-density optical disc 3 is recorded using the aspheric lens 183.
00 is recorded or reproduced, and the objective lens 18
5, the recording or reproduction of the low-density optical disk 200 can be performed.

The optical disk apparatus of the above embodiment may further include a photosensor for a high-density optical disk for detecting a reproduction signal of a transmission type high-density optical disk below the optical disk. Thereby, recording or reproduction of a transmission type high-density optical disk becomes possible.

FIGS. 10 and 11 are schematic views showing the structure of an optical disk device according to a fifth embodiment of the present invention.

FIG. 10 shows a transmission type high-density optical disk 110.
FIG. 11 shows the recording or reproduction of the reflection type low-density optical disk 200.

As shown in FIG. 10, in a transmission type high-density optical disk 110, a pit row 113 is provided on the surface side of a substrate 111, and the surface of the pit row 113 is covered with an ultraviolet curing resin 114. . Thus, the signal recording surface 112 is formed on the front surface side of the substrate 111.

On the other hand, as shown in FIG. 11, in the reflection type low-density optical disk 200, a pit row 203 is provided on the back side of the transparent substrate 201, and the pit row 203 is provided.
Is coated with a reflective film 204 such as an Al thin film, and further coated with an ultraviolet curable resin 205. As described above, the signal recording surface 202 is formed on the back surface side of the transparent substrate 201.

At the time of reproduction of the transmission type high-density optical disk 110, the transmitted light from the signal recording surface 112 is detected by the high-density optical disk photosensor 140, whereby
Signal reproduction is performed. Such a high-density optical disk photosensor 140 is arranged below the optical disk.

On the other hand, at the time of reproduction of the reflection type low-density optical disk 200, signal reproduction is performed by detecting the reflected light from the signal recording surface 202 with the low-density optical disk photosensor 137. Such a photosensor 137 for a low-density optical disk is arranged above the optical disk.

In FIG. 10, an optical head 121 includes an objective lens 122 and an optical unit 123. The optical unit 123 includes a support 124, a correction plate 125, and a hemispherical SIL 126. SIL12
The flat lower surface of 6 is a laser light emitting surface. Support 12
A correction plate 125 is mounted on the upper part of
The SIL 126 is attached to the lower part of.

The optical unit 123 is attached to one end of an arm 127 extending in the horizontal direction. Arm 12
A coil 128 is wound on the outer peripheral surface of the other end of the coil 7.
A magnet 129 is arranged around the coil 128 of the arm 127. The arm 127 is supported movably in the direction of arrow X.

By switching the direction of the current flowing through the coil 128, the optical unit 123 attached to the arm 127 is moved by the magnetic force of the coil 128 and the magnet 129 to a position below the objective lens 122 and the objective lens 1.
22 can be moved to a position deviated from below.

At the time of recording or reproduction on the high-density optical disk 110, the optical unit 123 moves to a position below the objective lens 122 as shown in FIG. The linearly polarized laser light emitted from the semiconductor laser element 131 is converted into parallel light by the collimator lens 132 and enters the polarization beam splitter 134. As a result, the laser light is reflected in the direction of the objective lens 122 by the polarization beam splitter 134 and is converted into a clockwise or counterclockwise circularly polarized laser light by the quarter-wave plate 135.
22. The laser light is narrowed down by the objective lens 122, passes through the correction plate 125 of the optical unit 123, and enters the SIL 126. Of the laser light incident on the SIL 126, the light 601 in the orbicular zone is totally reflected on the emission surface of the SIL 126, and evanescent light (near-field light) is irradiated on the signal recording surface 112 of the high-density optical disk 110. On the other hand, of the incident laser light,
00 is a signal recording surface 1 which is transmitted through the emission surface of the SIL 126.
The light is condensed at 12.

During reproduction of the high-density optical disk 110, the transmitted light of the central part 600 of the laser light from the signal recording surface 112 of the high-density optical disk 110 and the high-density optical disk 1
The transmitted light of the evanescent light from the ten signal recording surfaces 112 is condensed as transmitted light 602 on the light receiving surface of the photosensor 140 for a high-density optical disk. In this manner, the detection of the reproduction signal of the transmission type high-density optical disk 110 is performed. In this case, the transmitted light of the light 600 at the center of the laser light and the transmitted light of the evanescent light are collected on the high-density optical disc photosensor 140, so that a high-intensity reproduced signal is obtained. As a result, S / N (signal to noise ratio) is improved.

As shown in FIG. 11, at the time of recording or reproduction of the reflection type low-density optical disk 200, the optical unit 1
23 moves to a position deviated from below the objective lens 122. The linearly polarized laser light emitted from the semiconductor laser element 131 is converted into parallel light by the collimator lens 132 and enters the polarization beam splitter 134. As a result, the laser light is reflected by the polarizing beam splitter 134 in the direction of the objective lens 122, and the 光 wavelength plate 135
The laser light is converted into clockwise or counterclockwise circularly polarized laser light, and is transmitted through the transparent substrate 201 of the low-density optical disk 200 by the objective lens 122 to be focused on the signal recording surface 202.

At the time of reproduction of the low-density optical disk 200, the reflected light from the signal recording surface 202 of the low-density optical disk passes through the objective lens 122, and has a 90 ° polarization direction different from that of the incident laser light by the quarter-wave plate 135. The light is converted into linearly polarized laser light and passes through the polarization beam splitter 134. The laser beam transmitted through the polarizing beam splitter 134 is condensed by the condenser lens 136 on the light receiving surface of the low-density optical disk photosensor 137.

Semiconductor laser device 1 shown in FIGS. 10 and 11
As 31, for example, a semiconductor laser device that emits a laser beam having a wavelength of 650 nm is used. Further, the objective lens 1
22, the configuration and function of the correction plate 125 and the SIL 126 are the same as those of the objective lens 2, the correction plate 5 and the SIL 6 in FIGS.

The optical disk apparatus of this embodiment includes the photosensor 140 for high-density optical disk and the photosensor 137 for low-density optical disk.
By moving the first optical unit 123, it is possible to perform recording and reproduction on both the transmission type high density optical disc 110 and the reflection type low density optical disc 200.

FIGS. 12 and 13 are schematic views showing the structure of an optical disk device according to the sixth embodiment of the present invention.

FIG. 12 shows a transmission type high-density optical disk 110.
FIG. 13 shows the recording or reproduction of the reflection type low-density optical disk 200. The structures of the high-density optical disk 110 and the low-density optical disk 200 are as described above with reference to FIGS. In addition, the signal reproduction of the transmission type high-density optical disk 110 is performed by using the high-density optical disk photosensor 160 provided on the lower side of the optical disk. Is used.

As shown in FIGS. 12 and 13, the optical disk device has an optical head 141. Optical head 14
1 is an objective lens 142 for the high-density optical disk 110,
A hemispherical SIL 143 and an objective lens 144 for the low-density optical disc 200 are provided.

As shown in FIG.
When recording or reproducing the data, the semiconductor laser element 145 is used.
Is converted into parallel light by the collimator lens 146. By not applying a voltage to the liquid crystal 147, the polarization direction of the linearly polarized laser light is rotated by 90 °. As a result, the laser light is reflected by the polarizing beam splitter 148 in the direction of the objective lens 142. The laser light reflected by the polarization beam splitter 148 is converted into clockwise or counterclockwise circularly polarized laser light by a quarter-wave plate 149, and the objective lens 142
And is incident on the SIL 143. SIL1
Of the laser light incident on the laser beam 43, the light 604 in the annular zone is S
Evanescent light (near-field light) is totally reflected on the emission surface of the IL 143 and is irradiated on the signal recording surface 112 of the high-density optical disk 110. On the other hand, the light 603 at the center of the incident laser light is transmitted through the emission surface of the SIL 143 and focused on the signal recording surface 112.

During reproduction of the high-density optical disk 110, the transmitted light of the central part 603 of the laser light from the signal recording surface 112 of the high-density optical disk 110 and the high-density optical disk 1
The transmitted light of the evanescent light from the ten signal recording surfaces 112 is condensed as transmitted light 605 on the light receiving surface of the photosensor 160 for a high-density optical disk. Thus, the reproduction signal of the high-density optical disk 110 is detected. In this case, the transmitted light of the light 603 at the center of the laser light and the transmitted light of the evanescent light are condensed on the high-density optical disk photosensor 160, so that a high-intensity reproduced signal is obtained. As a result, S / N (signal to noise ratio)
Is improved.

As shown in FIG. 13, at the time of recording or reproduction on the reflection type low density optical disc 200, the linearly polarized laser light emitted from the semiconductor laser element 145 is converted by the collimator lens 146 into parallel light. In this case, by applying a voltage to the liquid crystal 147, the polarization direction of the linearly polarized laser light does not rotate by 90 °. as a result,
The laser light transmitted through the liquid crystal 147 passes through the polarization beam splitter 148, is converted into clockwise or counterclockwise circularly polarized laser light by the ４ wavelength plate 152, and is reflected by the mirror 67 in the direction of the objective lens 144. . Mirror 67
Is reflected by the objective lens 144, passes through the transparent substrate 201 of the low-density optical disc 200, and is focused on the signal recording surface 202.

At the time of reproduction of the low-density optical disk 200, the laser light is reflected by the signal recording surface 202 of the low-density optical disk 200, and becomes circularly polarized light in the opposite direction to that at the time of incidence.
The light passes through the objective lens 144 and is reflected by the mirror 67 in the direction of the polarization beam splitter 148. The laser light reflected by the mirror 67 is converted into linearly-polarized laser light having a 90 ° polarization direction different from that of the incident laser light by the quarter-wave plate 152, and is converted by the polarization beam splitter 148 toward the condenser lens 150. Is reflected. The laser beam reflected by the polarization beam splitter 148 is converted by the condenser lens 150 into a low-density optical disk photosensor 151.
Is collected on the light receiving surface of the.

The configuration and function of the liquid crystal 147 shown in FIGS. 12 and 13 are described with reference to the liquid crystal 27 shown in FIGS.
Is the same as

The optical disk device of this embodiment includes a photosensor 160 for a high-density optical disk and a photosensor 151 for a low-density optical disk.
1 is an objective lens 142 and S
The transmission-type high-density optical disc 1 includes the IL 143 and the objective lens 144 for the low-density optical disc 200.
It is possible to perform recording and reproduction on both the low-density optical disk 200 and the reflection type low-density optical disk 200.

FIG. 14 is a diagram showing another example of the SIL used in the optical head of the optical disk device of the first to sixth embodiments.

The SIL 81 shown in FIG. 14A has a substantially hemispherical upper surface and a flat lower surface, and has a columnar convex portion 82 at the center of the flat lower surface. The center of the lower surface of the convex portion 82 and S
The distance R between the top of the spherical surface of the IL 81 and the radius R is set to be the same as the radius of the spherical surface. As a result, the laser light that is perpendicularly incident on the spherical surface is focused on the center of the lower surface of the projection 82. This S
In the IL 81, the lower surface of the projection 82 serves as a laser light emission surface.

When the SIL 81 is used, the optical axis of the SIL 81 can be adjusted by aligning the projection 82 with the optical axis of the optical system.
21, 141, 161, 181 can be easily assembled and adjusted.

The SIL 83 shown in FIG. 14B has a partially spherical upper surface and an inverted truncated conical lower surface. SIL83
R between the center of the central portion 84 of the lower surface of the sphere and the top of the spherical surface
Is set to be the same as the radius of the spherical surface. As a result, the laser beam that is perpendicularly incident on the spherical surface is focused on the center of the central portion 84 on the lower surface. In this SIL 83, the central portion 84 on the lower surface serves as a laser light emission surface.

When the SIL 83 is used, the optical axis of the SIL 83 can be adjusted by aligning the central portion 84 on the lower surface with the optical axis of the optical system.
1, 121, 141, 161, and 181 are easily assembled and adjusted.

The SIL 85 shown in FIG. 14C has a substantially hemispherical upper surface and a flat lower surface, and has a cylindrical concave portion 86 at the center of the flat lower surface. The distance R between the center of the bottom surface of the recess 86 and the top of the spherical surface is set to be the same as the radius of the spherical surface. As a result, the laser beam that is perpendicularly incident on the spherical surface is focused on the center of the bottom surface of the concave portion 86. In the SIL 85, the bottom surface of the concave portion 86 becomes the laser light emission surface.

When the SIL 85 is used, the optical axis of the SIL 85 can be adjusted by aligning the concave portion 86 with the optical axis of the optical system.
1, 141, 161, and 181 are easily assembled and adjusted.

In the first to sixth embodiments, the optical disk in which a signal is recorded by using pits is described. However, the present invention can be applied to an optical disk in which a signal can be reproduced by a difference in reflectance. .

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of an optical disk device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of an optical disc device according to a first embodiment of the present invention.

FIG. 3 is a schematic diagram showing an optical head during recording or reproduction of a high-density optical disk and a low-density optical disk in the optical disk devices of FIGS. 1 and 2;

FIG. 4 is a schematic diagram illustrating a configuration of an optical disc device according to a second embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating a configuration of an optical disc device according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating functions of a Pockels cell.

FIG. 7 is a diagram showing functions of a Faraday element.

FIG. 8 is a schematic diagram illustrating a configuration of an optical disc device according to a third embodiment of the present invention.

FIG. 9 is a schematic diagram illustrating a configuration of an optical disc device according to a fourth embodiment of the present invention.

FIG. 10 is a schematic diagram illustrating a configuration of an optical disc device according to a fifth embodiment of the present invention.

FIG. 11 is a schematic diagram showing a configuration of an optical disc device according to a fifth embodiment of the present invention.

FIG. 12 is a schematic diagram illustrating a configuration of an optical disc device according to a sixth embodiment of the present invention.

FIG. 13 is a schematic diagram illustrating a configuration of an optical disc device according to a sixth embodiment of the present invention.

FIG. 14 is a diagram illustrating another example of the SIL.

FIG. 15 is a schematic diagram showing an optical system of an optical disk device using a conventional recording / reproducing method.

FIG. 16 is a schematic diagram showing an optical system of an optical disk device using a near-field recording / reproducing method.

[Explanation of symbols]

1,21,121,141,161,181 Optical head 2,22,24,122,142,144,162,1
82,185 Objective lens 3,123,163 Optical unit 4,124,164,198 Support 5,125,165 Correction plate 6,23,81,83,85,126,143,16
7,184 SIL 7,127,170,197 Arm 8,128,168,195 Coil 9,129,169,196 Magnet 11,25,131,145,171,186 Semiconductor laser device 12,26,132,146,146 172,187 Collimator lens 14,28,134,148,174,189 Polarizing beam splitter 15,29,32,135,149,152,175
190,193 quarter wave plate 17,31,137,140,151,160,17
7,192 Photosensor 27,147,188 Liquid crystal 60 Pockels skeleton 70 Faraday element 100,110,300 High density optical disk 101,201,301 Substrate 102,202,302 Signal recording surface 200 Low density optical disk

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yasuyuki Kano 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Yoichi Tsuchiya 2-5-2 Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. F term (reference) 5D119 AA04 AA11 AA22 AA41 BA01 BB11 EC22 JA09 JA43 JA44 JC04

Claims (13)

[Claims] 1. An optical head for selectively recording or reproducing data on or from a first optical disc having a signal recording surface formed on a rear surface of a transparent substrate and a second optical disc having a signal recording surface formed on a front surface of the substrate. An objective lens for condensing light on the signal recording surface through the transparent substrate of the first optical disc during recording or reproduction of the first optical disc; and the objective lens for recording or reproducing the second optical disc. 2. An optical head, comprising: a solid immersion lens for irradiating near-field light to the signal recording surface of the second optical disc. 2. An optical head for selectively recording or reproducing data on a first optical disk having a signal recording surface formed on the rear surface side of a transparent substrate and a second optical disk having a signal recording surface formed on the front surface side of the substrate. An objective lens for condensing light on the signal recording surface through the transparent substrate of the first optical disc during recording or reproduction of the first optical disc, and an objective lens for recording or reproducing the second optical disc. A correction plate movably provided in an optical path between a lens and the second optical disk, and having an optical characteristic equivalent to that of the transparent substrate of the first optical disk; The optical disk is provided movably in an optical path between the correction plate and the second optical disk, and collects light transmitted through the objective lens and the correction plate so as to be in front of the second optical disk. An optical head, comprising: a solid immersion lens that irradiates a near-field light to the signal recording surface. 3. An optical head that selectively records or reproduces data on a first optical disc having a signal recording surface formed on the back surface of a transparent substrate and on a second optical disc having a signal recording surface formed on the front surface of the substrate. A first objective lens for condensing light on the signal recording surface through the transparent substrate of the first optical disc during recording or reproduction of the first optical disc; and recording or reproduction of the second optical disc. A solid immersion lens that irradiates the signal recording surface of the second optical disc with near-field light at times, and a second objective lens that guides light to the solid immersion lens during recording or reproduction of the second optical disc. An optical head characterized in that: 4. A first optical disk having a signal recording surface formed on the rear surface of a transparent substrate, a second optical disk having a signal recording surface formed on the front surface of the substrate, and a signal recording surface formed on the front surface of the substrate. An optical head for selectively recording or reproducing data on or from a third optical disk on which a signal is formed, wherein light is recorded on the signal recording surface through the transparent substrate of the first optical disk when recording or reproducing on the first optical disk. An objective lens for converging light, and a movable substrate provided in the optical path between the objective lens and the second optical disk during recording or reproduction of the second optical disk, and A first correction plate having equivalent optical characteristics; and a movable optical path between the first correction plate and the second optical disk during recording or reproduction of the second optical disk; A solid immersion lens for condensing light transmitted through the lens and the eleventh correction plate and irradiating near-field light to the signal recording surface of the second optical disc; A second correction plate movably provided in an optical path between the objective lens and the third optical disk and having optical characteristics equivalent to the transparent substrate of the first optical disk; and the third optical disk The optical disk is provided so as to be movable in an optical path between the second correction plate and the third optical disk at the time of recording or reproducing, and transmits the light transmitted through the objective lens and the second correction plate to the third optical disk. And an aspheric lens for converging light on the signal recording surface. 5. A first optical disk having a signal recording surface formed on the rear surface of a transparent substrate, a second optical disk having a signal recording surface formed on the front surface of the substrate, and a signal recording surface formed on the front surface of the substrate. An optical head for selectively recording or reproducing data on or from a third optical disk on which a signal is formed, wherein light is recorded on the signal recording surface through the transparent substrate of the first optical disk when recording or reproducing on the first optical disk. A first objective lens for converging light; a solid immersion lens for irradiating near-field light to the signal recording surface of the second optical disc during recording or reproduction of the second optical disc; An aspherical lens for condensing light on the signal recording surface of the third optical disc during recording or reproduction; and the solid image recording or reproducing on the second or third optical disc. The optical head is characterized in that a second objective lens for guiding light to John lens or the aspherical lens. 6. The solid immersion lens has a partially spherical entrance surface and a lower surface including a planar exit surface having a predetermined diameter at a central portion, and a lower surface around the exit surface is defined as an exit surface. 2. The method according to claim 1, wherein the first and second surfaces are formed on different surfaces.
6. The optical head according to any one of items 1 to 5, 7. An optical disk apparatus for selectively recording or reproducing data on or from a first optical disk having a signal recording surface formed on a rear surface of a transparent substrate and a second optical disk having a signal recording surface formed on a front surface of the substrate. A light source for emitting light; an objective lens for condensing light on the signal recording surface through the transparent substrate of the first optical disc during recording or reproduction of the first optical disc; and the second optical disc A correction plate which is movably provided in an optical path between the objective lens and the second optical disk during recording or reproduction of the optical disk, and has optical characteristics equivalent to a transparent substrate of the first optical disk; The optical disk is provided movably in an optical path between the correction plate and the second optical disk during recording or reproduction of the optical disk, and collects light transmitted through the objective lens and the correction plate to form A solid immersion lens for irradiating the signal recording surface of the second optical disc with near-field light; a photodetector for detecting light; and a light emitted from the light source to the objective lens and transmitted through the objective lens. An optical system for guiding the return light from the first or second optical disk to the photodetector. 8. An optical disk apparatus for selectively recording or reproducing data on a first optical disk having a signal recording surface formed on the rear surface of a transparent substrate and a second optical disk having a signal recording surface formed on the front surface of the substrate. A light source for emitting light; a first objective lens for condensing light on the signal recording surface through the transparent substrate of the first optical disc during recording or reproduction of the first optical disc; A solid immersion lens for irradiating near-field light to the signal recording surface of the second optical disc during recording or reproduction of the second optical disc; and a solid immersion lens for guiding light to the solid immersion lens during recording or reproduction of the second optical disc. An objective lens, a photodetector for detecting light, and a first pair of light emitted from the light source during recording or reproduction of the first optical disc. It guides the return light from the first optical disc that has passed through the first objective lens to the object lens and guides the return light to the photodetector, and the light emitted from the light source during recording or reproduction of the second optical disc. An optical system that guides the return light from the second optical disk that has passed through the solid immersion lens and the second objective lens to the second objective lens and that has passed through the second objective lens to the photodetector. Optical disk device. 9. A first optical disk having a signal recording surface formed on the back surface of a transparent substrate, a second optical disk having a signal recording surface formed on the front surface of the substrate, and a signal recording surface formed on the front surface of the substrate. An optical disk device for selectively recording or reproducing data on or from a third optical disk on which is formed a light source, a light source for emitting light, and the transparent substrate of the first optical disk when recording or reproducing on the first optical disk An objective lens for condensing light on the signal recording surface through the optical disc; and a movably provided optical path between the objective lens and the second optical disc during recording or reproduction of the second optical disc; A first correction plate having optical characteristics equivalent to that of a transparent substrate of the optical disk, and movable in an optical path between the first correction plate and the second optical disk during recording or reproduction of the second optical disk. A solid immersion lens for converging light transmitted through the objective lens and the first correction plate and irradiating near-field light to the signal recording surface of the second optical disc; A second correction plate movably provided in an optical path between the objective lens and the third optical disk during recording or reproduction of the optical disk, and having an optical characteristic equivalent to a transparent substrate of the first optical disk; The optical disk is provided movably in an optical path between the second correction plate and the third optical disk during recording or reproduction of the third optical disk, and transmits light transmitted through the objective lens and the second correction plate. An aspherical lens for converging light on the signal recording surface of the third optical disc; a photodetector for detecting light; a light emitted from the light source to the objective lens; Wherein the first optical disk apparatus characterized by comprising an optical system for guiding the returned light from the second or third optical disc to the photodetector. 10. A first optical disk having a signal recording surface formed on the back surface of a transparent substrate, a second optical disk having a signal recording surface formed on the front surface of the substrate, and a signal recording surface formed on the front surface of the substrate. An optical disk device for selectively recording or reproducing data on or from a third optical disk on which is formed a light source, a light source for emitting light, and the transparent substrate of the first optical disk when recording or reproducing on the first optical disk A first objective lens for condensing light on the signal recording surface through the optical disk; a solid immersion lens for irradiating near-field light to the signal recording surface of the second optical disk during recording or reproduction of the second optical disk; An aspheric lens for condensing light on the signal recording surface of the third optical disc during recording or reproduction of the third optical disc; A second objective lens for guiding light to the solid immersion lens or the aspherical lens during reproduction; a photodetector for detecting light; and a light emitted from the light source during recording or reproduction of the first optical disc. The return light from the first optical disc, which has been guided to the first objective lens and transmitted through the first objective lens, is guided to the photodetector, and emitted from the light source during recording or reproduction of the second optical disc. Guided to the second objective lens, and guides return light from the second optical disc that has passed through the solid immersion lens and the second objective lens to the photodetector. During recording or playback,
An optical system that guides light emitted from the light source to the second objective lens and guides return light from the third optical disc that has passed through the aspheric lens and the second objective lens to the photodetector; An optical disk device comprising: 11. The optical system according to claim 1, wherein the optical system switches a polarization direction of light between recording or reproduction of the first optical disk and recording or reproduction of the second or third optical disk.
11. The optical disk device according to claim 10, further comprising: an optical element, and a second optical element that switches a traveling direction of the light according to a polarization direction of the light transmitted through the first optical element. 12. A selective recording on a reflection-type first optical disk having a signal recording surface formed on the rear surface side of a transparent substrate and a transmission-type second optical disk having a signal recording surface formed on the front surface side of the substrate. Or an optical disc device that performs reproduction, and a light source that emits light; and an objective lens that condenses light on the signal recording surface through the transparent substrate of the first optical disc during recording or reproduction of the first optical disc. A correction plate provided so as to be movable in an optical path between the objective lens and the second optical disk during recording or reproduction of the second optical disk, and having optical characteristics equivalent to a transparent substrate of the first optical disk; And a movably provided optical path between the correction plate and the second optical disk during recording or reproduction of the second optical disk, and transmitting through the objective lens and the correction plate. A solid immersion lens for converging the reflected light and irradiating near-field light to a signal recording surface of the second optical disc; and a first light detection for detecting reflected light of the signal recording face of the first optical disc. Device, a second photodetector for detecting light transmitted through the signal recording surface of the second optical disc, and light emitted from the light source for recording or reproducing the first optical disc to the objective lens. The first light detector guides the reflected light from the first optical disc that has passed through the objective lens to the first photodetector, and converts the light emitted from the light source into the objective lens when recording or reproducing the second optical disc. An optical disk device comprising: an optical system that guides the optical disk. 13. A selective recording on a reflective first optical disk having a signal recording surface formed on the rear surface side of a transparent substrate and a transmission type second optical disk having a signal recording surface formed on the front surface side of the substrate. Or a light source for emitting light, and a first light source for condensing light on the signal recording surface through the transparent substrate of the first optical disc during recording or reproduction of the first optical disc. An objective lens, a solid immersion lens for irradiating near-field light to the signal recording surface of the second optical disc during recording or reproduction of the second optical disc, and a solid immersion lens for recording or reproduction of the second optical disc A second objective lens for guiding light to a lens; a first photodetector for detecting reflected light from the signal recording surface of the first optical disc; A second photodetector for detecting light transmitted through the signal recording surface of the disc, and guiding light emitted from the light source to the first objective lens during recording or reproduction of the first optical disc; The reflected light from the first optical disc that has passed through the first objective lens is guided to the first photodetector, and the light emitted from the light source is written to the second optical disc during recording or reproduction on the second optical disc. And an optical system for guiding to the objective lens.