JP2001143295A - Method and device for reproducing information from optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for reproducing the information from an optical recording medium by means of the near field light with high accuracy and with suppression of the disturbance light (noises) caused in an information reproduction mode. SOLUTION: This information reproducer reproduces the information from an optical information recording medium 10 having a projecting/recessing texture 11 on its surface 10' and uses a slider 30 which floats by an air film lubrication theory and by moving relatively the information (recording pits) 12 recorded on the medium 10 to the medium 10 and also can irradiate the near field light on the medium 10 for reproducing the information. Thus, the slider 30 irradiates the near field light on the medium 10 and the information is reproduced from the medium 10 by detecting the light reflected on the medium 10. The slider 30 has a near field light emitting aperture P to irradiate the near field light on the medium 10 and the diameter (d) of the part P is smaller than the array pitch Tp of the texture 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for reproducing information from an optical recording medium.

[0002]

2. Description of the Related Art There are various types of media for recording information, among which are optical recording media. The optical recording medium is configured such that information is recorded on the medium by irradiating the medium with light from a head for irradiating the medium, or light from the medium is irradiated by light from the head (for example, reflected light)
Is detected, and the information recorded on the medium is reproduced (read). In addition, the optical recording medium is usually provided with a tracking guide such as a guide groove for tracking control and a mark for sample servo for tracking control. By causing the head to follow the tracking guide, the optical recording medium is provided. Is recorded and reproduced.

In order to record information on an optical recording medium with high density, it has been proposed to record information using near-field light and to reproduce (read) the information using near-field light. I have. For example, a head having a near-field light emission opening for irradiating near-field light to an optical recording medium is used as the head, and near-field light for information recording is recorded on the optical recording medium from the near-field light emission opening. By irradiating the medium, information is recorded on the medium, or by irradiating the optical recording medium with near-field light for information reproduction from the near-field light emission opening, reflected light reflected from the medium It is proposed that the information recorded on the medium is reproduced by picking up the information at the opening.

[0004] The near-field light is characterized in that it exists only in the vicinity of the near-field light emission opening, and that the intensity of the near-field light greatly depends on the distance from the near-field light emission opening. Therefore, when recording or reproducing information using near-field light, the distance between the near-field light emission opening and the optical recording medium must be maintained at about several tens of nm.

As one of means for this purpose, it has been proposed to use a slider type head which floats on the principle of air film lubrication used for recording and reading information in a hard disk drive (magnetic recording device) ( For example, see JP-A-9-128787. The flying principle is that, for example, a disk-shaped recording medium is rotated at a constant speed, and the slider flies a predetermined distance from the surface of the medium by a floating force caused by an air flow generated between the slider and the recording medium. Thus, the distance between the surface of the recording medium and the slider or the head is appropriately maintained.

When such a slider or a head is used, it has been proposed to provide an uneven texture on the optical recording medium in order to prevent the slider or the head from being attracted to the optical recording medium (for example, see Japanese Patent Application Laid-Open No. 9-128787). . The uneven texture is fine unevenness formed on the surface of the optical recording medium at a predetermined arrangement pitch. For example, while rotating a disk-shaped recording medium, fine diamond or aluminum oxide (Al ₂ O ₃ ) is dispersed. The disk surface is concentrically formed by rubbing the disk surface with the tape.

[0007]

However, information recorded on an optical recording medium provided with such a texture can be transferred from a near-field light emitting opening for irradiating the medium with near-field light. When irradiating the medium with near-field light and thereby picking up and reproducing reflected light reflected from the medium at the opening, there are the following difficulties.

That is, in order to collect as much reflected light as possible when collecting the reflected light from the optical recording medium at the near-field light exit opening, it is desirable that the diameter of the near-field light exit opening be large. If the diameter of the opening is too large, the spot size of light irradiation on the optical recording medium becomes large. On the other hand, the size of the spatial localization of the evanescent light that can efficiently pick up the reflected light from the optical recording medium is determined according to the size of the opening diameter. Therefore, if the diameter of the near-field light emission opening is too large, the evanescent light in the spatially unnecessary dimension other than the recording information that is not necessary is also picked up as reflected light. Lower the / N ratio.

The evanescent light within the spatially unnecessary dimension which is not originally required is often caused by the texture of the medium surface. In addition, the optical recording medium is usually provided with a tracking guide such as a guide groove for tracking control and a mark for sample servo for tracking control. However, such a tracking guide may similarly cause noise. is there.

Accordingly, the present invention relates to a method for reproducing information from an optical recording medium using near-field light, wherein the light capable of accurately reproducing information by suppressing the generation of disturbance light (the generation of noise) during the reproduction of information. It is an object to provide a method for reproducing information from a recording medium. Further, the present invention relates to an apparatus for reproducing information from an optical recording medium using near-field light, wherein the apparatus reproduces information with high accuracy by suppressing the occurrence of disturbance light (noise generation) at the time of information reproduction. It is an object of the present invention to provide an information reproducing apparatus.

[0011]

Means for Solving the Problems The present inventor has conducted various studies to solve the above-mentioned problems, and has found the following.
That is, information recorded on the medium from an optical recording medium having an uneven texture on the surface is irradiated with near-field light onto the medium from a near-field light emission opening for irradiating the medium with near-field light. Thus, when the reflected light reflected from the medium is picked up at the opening and reproduced, the spatial frequency component of the noise included in the reflected light picked up at the opening is determined by the arrangement pitch of the uneven texture of the medium. There is a large component in the position. Paying attention to this, when the near-field light emission opening is adopted as the near-field light emission opening having an opening diameter smaller than the arrangement pitch of the uneven texture of the optical recording medium to reproduce such information, the reflected light has noise. Is suppressed, and the S / N ratio of the information reproduction signal is improved.

Further, as a result of research, the present inventor has found that an optical recording having an uneven texture on the surface and a tracking guide such as a guide groove for tracking control and a mark for sample servo for tracking control is provided. When information recorded on the medium from the medium is reproduced using near-field light in the same manner as described above, the near-field light emission opening is smaller than the arrangement pitch of the uneven texture of the medium, and the medium It has also been found that the adoption of a near-field light emission opening having an opening diameter smaller than the width of the tracking guide suppresses noise from being included in the reflected light and improves the S / N ratio of the information reproduction signal.

The present invention is based on this finding,
In order to solve the above-mentioned problems, the following method and apparatus for reproducing information from an optical recording medium are provided. (1) Method for Reproducing Information from Optical Recording Medium Information recorded on the medium from an optical recording medium having an uneven texture on its surface is moved relative to the medium so that it floats on the principle of air film lubrication. The medium is reproduced using a slider capable of irradiating near-field light for information reproduction, and the slider has a near-field light emission opening for irradiating the optical recording medium with near-field light, and Using a slider whose opening diameter is smaller than the arrangement pitch of the uneven texture, irradiating the medium with near-field light from the opening, detects reflected light reflected from the medium, and reproduces information. Characteristic information reproducing method from an optical recording medium. (2) Apparatus for reproducing information from an optical recording medium Information recorded on the medium from an optical recording medium having an uneven texture on its surface is moved relative to the medium so that it floats based on the principle of air film lubrication. Using a slider capable of irradiating near-field light for information reproduction on the medium, irradiating the optical recording medium with near-field light from the slider,
An information reproducing apparatus from an optical recording medium for detecting and reproducing reflected light reflected from the medium, wherein the slider is a near-field light emission opening for irradiating the optical recording medium with near-field light. Wherein the diameter of the opening is smaller than the arrangement pitch of the uneven texture. The optical recording medium includes an optical recording medium capable of recording, reproducing and erasing information, and a read-only optical recording medium (that is, an optical recording medium on which information is already recorded and which can only reproduce the information). Either may be used.

According to the method and apparatus for reproducing information from an optical recording medium according to the present invention, the optical recording medium moves relative to an optical recording medium having an uneven texture on the surface to float by the principle of air film lubrication and reproduce information on the medium. A slider that can emit near-field light is used. The slider has a near-field light emission opening for irradiating the optical recording medium with near-field light, and the diameter of the opening is smaller than the arrangement pitch of the uneven texture.

The slider which flies by the air film lubrication principle is also called a flying head, and the slider and the optical recording medium move relatively (usually, the optical recording medium is rotated. In this case, the air-floating film generated between the slider and the optical recording medium flies a predetermined distance from the optical recording medium. The uneven texture is usually provided on an optical recording medium in order to prevent the slider from adsorbing to the optical recording medium. For example, while rotating the medium, fine diamond or aluminum oxide (A
l ₂ O ₃ ) or the like is formed by rubbing the surface of the medium with a tape in which the tape is dispersed. The arrangement pitch is not limited to this, but may be about 0.3 μm.

In the method and apparatus for reproducing information from an optical recording medium according to the present invention, when reproducing information recorded on the optical recording medium, the slider moves relatively to the medium. When the slider moves relative to the medium, an air flow is generated between the slider and the optical recording medium by the air film lubrication principle, and the film of the air flow causes the slider to move from the optical recording medium. By floating a predetermined distance, the distance between the surface of the optical recording medium and the slider or the near-field light emission opening is kept constant. Then, the information recorded on the optical recording medium is reproduced by irradiating the medium with near-field light from the near-field light emission opening, thereby picking up reflected light reflected from the medium at the opening. I do.

According to the method and apparatus for reproducing information from an optical recording medium according to the present invention, the diameter of the near-field light emission opening of the slider is smaller than the arrangement pitch of the uneven texture of the optical recording medium. Noise included in the reflected light can be suppressed, and the S / N ratio of the information reproduction signal can be improved. As a result, the occurrence of disturbance light (the occurrence of noise) during information reproduction can be suppressed and the information can be reproduced with high accuracy.

In the method and apparatus for reproducing information from an optical recording medium according to the present invention, the optical recording medium may have an uneven texture on its surface and may have a guide groove for tracking control or a mark for sample servo for tracking control. An optical recording medium having a tracking guide can be employed. In this case, the tracking guide may cause noise. For example, when an optical recording medium having an uneven texture on the surface and having a guide groove for tracking control is employed, the slider may be used as the slider. By using a slider whose field light emission opening diameter is smaller than the arrangement pitch of the uneven texture and smaller than the width of the guide groove for tracking control, a sample servo for unevenness texture on the surface and tracking control is provided. When an optical recording medium having marks for use in the optical recording medium is adopted, the slider having the near-field light emission opening diameter smaller than the arrangement pitch of the uneven texture and smaller than the width of the sample servo mark is used as the slider. Is used to suppress noise contained in the reflected light picked up at the opening. Can, it is possible to improve the S / N ratio of information reproduction signal.

In any case, if the diameter of the near-field light emission opening is too small, noise is suppressed, but reflected light from information recorded on the optical recording medium is also picked up by the limitation due to the size of the opening. It becomes difficult. Therefore, the diameter of the opening is desirably large enough to efficiently pick up the reflected light from the recorded information on the optical recording medium. In any case, in the method and apparatus for reproducing information from the optical recording medium of the present invention, a near-field light emitting probe is mounted as the slider, and the tip for emitting near-field light of the probe is made of a dielectric material. And a metal film covering the side peripheral surface of the optical waveguide portion, and a part of the optical waveguide portion has a cone shape or a truncated cone shape from the metal film as a near-field light emission opening. A slider whose bottom surface diameter is the diameter of the near-field light emission opening portion.

According to such a slider, when irradiating the optical recording medium with near-field light, the light guided to the optical waveguide portion passes through the opening where the diffraction of light is restricted by the metal film. It becomes evanescent light existing near the surface of the protruding exposed portion, and the light intensity at the sharp portion of the protruded exposed portion is increased, so that the narrowed light can be applied to the optical recording medium.

The pyramidal shape may be any of pyramidal shapes such as a quadrangular pyramid and a hexagonal pyramid, in addition to the conical shape. As for the frustum shape, in addition to the frustum shape,
The shape may be any of truncated pyramids such as truncated pyramids and truncated hexagons.
If the height of the protruding exposed portion in the shape of a cone or a truncated cone is too high, it is difficult to obtain an appropriate value of the bottom diameter, that is, the diameter of the near-field light emission opening, for example, at about several hundred nm.
Therefore, the height of the projecting exposed portion is about several tens of nm,
nm or less.

In the case where the shape of the projecting exposed portion is a frustum shape, a thin wire made of metal, for example, silver (Ag) is projected from the inside of the projecting exposed portion from the upper surface of the frustum of the projecting exposed portion. You may. By doing so, the light intensity of the sharp portion of the protruding exposed portion is further increased, which is advantageous in irradiating the optical recording medium with near-field light.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration of a part of an example of an information reproducing apparatus for executing a method of reproducing information from an optical recording medium according to the present invention. The information reproducing apparatus shown in FIG. 1 includes a head device 100, an optical recording medium storage unit 200, and the like, and reproduces information from the optical recording medium 10 stored in the optical recording medium storage unit 200 using near-field light. be able to. That is, the head device 100 is
0, and the near-field light emission probe 34 is mounted on the slider 30. Then, by irradiating information recorded on the medium 10 from the optical recording medium 10 with near-field light for reproduction from the near-field light emitting probe 34 to the medium 10, reflected light reflected from the medium 10 is detected. Perform playback. Further, the head device 100 is provided with a tracking head (not shown) separately from the near-field light emission probe 34, and irradiates the optical recording medium 10 with tracking light from the tracking head. The reflected light is detected by a tracking information detection device (not shown) to perform tracking control.

The optical recording medium accommodating section 200 is provided with a rotation drive device (not shown), and can accommodate the disk-shaped optical recording medium 10. The optical recording medium 10 is fixed to a rotation shaft 20 of the rotary drive device, and is driven to rotate in the circumferential direction A in the figure by the rotary drive by the rotary drive device. FIG. 2A is a perspective view of the optical recording medium 10 shown in FIG. 1, and FIG. 2B is a plan view in which a portion α of the optical recording medium 10 is enlarged.
(C) shows the recording medium radial direction X of a part α of the optical recording medium 10.
FIG. In FIG. 2A, a recording pit 12, which will be described later, is not shown. In FIG. 2B and FIG. 2C, a tracking guide 13 described later is not shown.

As shown in FIG. 2A, the optical recording medium 10
Has an uneven texture 11 on its surface 10 '.
The uneven texture 11 is fine unevenness formed on the optical recording medium surface 10 'at a predetermined arrangement pitch. That is,
The uneven texture 11 is usually provided to prevent the slider 30 from adsorbing to the optical recording medium 10, and as shown in FIG. 2B and FIG. Array pitch (Tp in the figure, here 0.3 μm)
m) are minute concave and convex portions formed by the concave portions 11a and the convex portions 11b. The height difference between the concave portion 11a and the convex portion 11b (h in FIG. 2C) is 0.05 μm here.

Information is recorded on the optical recording medium 10 in advance. That is, as shown in FIGS. 2B and 2C, recording pits 12 are formed here as recording information. The pit size here is 0.1 μm. By irradiating the recording pit 12 with near-field light, information is reproduced. Further, the optical recording medium 10 is provided with a tracking guide 13 for tracking control, as shown in FIG. As the tracking guide 13, a guide groove or a sample servo mark can be employed.

FIG. 3 is a view showing a part of a state in which a guide groove 131a for tracking control is formed on the surface 10 'of the optical recording medium 10, and FIG. 3A is a plan view thereof.
FIG. 3B shows a cross-sectional view thereof. FIG. 4 is a diagram showing a part of a state in which a sample servo mark 131b for tracking control is formed on the surface 10 'of the optical recording medium 10, and FIG. 4A is a plan view thereof. , FIG.
(B) shows a cross-sectional view thereof. In FIGS. 3 and 4, the texture 11 is not shown.

The tracking control guide groove 131a is a continuous groove formed on the medium surface 10 'and extending in the medium circumferential direction A as shown in FIG. 3, and the sample servo mark 131b for tracking control is As shown in FIG. 4, there are two pit-shaped marks formed on the medium surface 10 'and arranged in a direction B crossing the medium circumferential direction A at predetermined intervals in the medium circumferential direction A.

The tracking control guide groove 131a
(R in FIG. 3A), sample servo mark 13
The width of 1b (R in FIG. 4 (A)) is, here, 0.
8 μm. In the optical recording medium 10, tracking light from a tracking head (not shown)
By irradiating the groove 131a shown in FIG. 3 and detecting the reflected light from the groove 131a, the mark 13 shown in FIG.
1b, the tracking control is performed by detecting the reflected light from the mark 131b.

The head device 100 shown in FIG. 1 includes a slider 30, an optical fiber 40, a suspension 50, a radial driving device 60, and an optical system 70. The suspension 50 holds the slider 30 on the one hand and is connected to the radially movable part of the radial drive 60 on the other hand. In the suspension 50, the holding portion 52 of the slider 30 is connected to the connection portion 51 with the radial driving device 60.
Can be moved in the slider lifting / lowering direction (Y direction in the figure). This allows the slider 30 to move in the Y direction in the figure.

The radial driving device 60 can move the suspension 50 and the slider 30 integrally along the surface 10 ′ of the optical recording medium 10 in the recording medium radial direction (X direction in the figure). The slider 30 is similar to that used for recording and reading information in a hard disk drive (magnetic recording device), and floats on the principle of air film lubrication.

FIG. 5 is an enlarged view of the slider 30 shown in FIG. 1 and its periphery, and FIG. 6 is a slider 30 shown in FIG.
FIG. 2 is a perspective view as viewed obliquely from below. 5 and 6, the suspension 50 is not shown. The slider 30 has a slider surface 31 (see the hatched portion in FIG. 6) facing the surface 10 ′ of the optical recording medium 10, and moves relatively to the optical recording medium 10. When the optical recording medium 10 is rotated in the direction A as shown in FIG. 2, the slider 30 is separated from the optical recording medium 10 by a predetermined distance (see FIG. 4) by a buoyancy force F caused by an air flow W generated between the slider surface 31 and the optical recording medium 10. (Medium G, about 60 nm in this case). Thereby, the distance between the optical recording medium surface 10 'and the opening P of the slider 30 or the near-field light emitting probe 34 described later is kept constant.

The slider 30 is provided with a fiber fitting hole 32 at a position shifted from the center of gravity of the slider 30 toward the air flow outlet 33 on the slider surface 31. Fiber 4
Reference numeral 0 indicates that one end 41 is fitted in the hole 32 of the slider 30 and the other end is connected to the optical system 70 in FIG. Further, the near-field light emitting probe 34 is mounted on the slider 30, and the probe 34 is connected to the end 41 of the fiber 40. As the near-field light emission probe 34, a fiber type probe or a coaxial probe can be employed.

FIG. 7A shows a state before the fiber type near-field light emitting probe 34 is mounted on the slider 30.
FIG. 7B is a perspective view of a fiber type near-field light emitting probe 34 mounted on the slider 30. FIG. FIG. 8A
Denotes a slider 30 of the near-field light emitting probe 34 having a coaxial shape.
FIG. 8B is a cross-sectional view of a part of the probe 34 b showing a state before being mounted on the slider 30. FIG. 8B is a perspective view of the coaxial near-field light emitting probe 34 mounted on the slider 30.

The probe 34a shown in FIG.
Optical fiber (optical waveguide) consisting of 41 and cladding 342
After the tip portion 35 is sharpened by chemical etching, a metal, here, aluminum (Al) is vapor-deposited on the peripheral portion, thereby forming the metal film 3.
7 is given. Here, since aluminum does not easily adhere to the sharpened distal end, the near-field light emission opening P is formed by forming a film of aluminum normally. The tip portion 34a 'of the probe 34a is mounted on the slider 30 as a fiber type near-field light emission probe 34.

This fiber type near-field light emitting probe 3
As shown in FIG. 7B, reference numeral 4 denotes an optical waveguide portion 36a whose distal end portion 34 'is made of a dielectric material (here, glass) and a metal (here, aluminum) film 37 which covers the side peripheral surface of the optical waveguide portion 36a. And a part of the optical waveguide portion 36a is projected and exposed as a near-field light emission opening P from the metal film 37 into a cone shape, here a cone shape. The diameter of the bottom surface of the protruding exposed portion 38 is the diameter d of the near-field light emission opening.

The probe 34b shown in FIG. 8A is formed as follows. That is, a thin wire 39 made of a metal, in this case, silver (Ag) is passed through the inside of a hollow pipette (optical waveguide portion) 36b which is a glass tube, and they are integrally pulled and cut while applying heat to cut the glass tube 36b. Create a sharpened tip. At this time, the metal part 39 is projected from the tip of the glass tube 36b,
The heating and tension conditions are adjusted. Further, a metal, in this case, aluminum (Al) is vapor-deposited on the tip portion, and this is used as a light shielding film 37. At this time, aluminum does not easily adhere to the sharpened tip, so that only the tip remains without being formed into a film, and the near-field light emission opening P is formed. The tip 34b 'of the probe 34b is mounted on the slider 30 as a near-field light emitting probe 34 having a coaxial shape.

This coaxial near-field light emitting probe 34
As shown in FIG. 8B, the optical waveguide 36b and the optical waveguide 3 whose tip 34 'is made of a dielectric material (here, glass).
Metal covering the side peripheral surface of 6b (aluminum here)
A part of the optical waveguide portion 36b is formed as a near-field light emission opening P and is projected and exposed from the metal film 37 in a truncated cone shape, here a truncated cone shape. And protruding exposed part 3
8, a thin wire 3 made of metal, in this case, silver (Ag)
9 protrudes from the upper surface of the truncated cone of the protruding exposure portion 38. The diameter of the bottom surface of the protruding exposed portion 38 is the diameter d of the near-field light emission opening.

The diameter d of the near-field light emission opening is 0.1 μm here. FIG. 9A is a diagram for comparing the opening diameter d of the fiber type near-field light emitting probe 34 with the arrangement pitch Tp of the uneven texture 11 in the optical recording medium 10, and FIG. FIG. 3 shows a diagram for comparing the aperture diameter d of the near-field light emission probe 34 having a shape with the arrangement pitch Tp of the uneven texture 11 in the optical recording medium 10.

As shown in FIG. 9, the near-field light emission opening diameter d (here, 0.1 μm) is smaller than the arrangement pitch Tp (here, 0.3 μm) of the uneven texture 11 of the optical recording medium 10. When the medium having the tracking control guide groove 131a shown in FIG. 3 is used as the optical recording medium 10, the aperture diameter d is set to the width R of the guide groove 131a (see FIG. 3, here 0.8 μm). Less than. Optical recording medium 10
When a medium having a sample servo mark 131b for tracking control shown in FIG. 4 is used, the width R of the mark 131b (see FIG. 4, here, 0.8
μm).

The near-field light emitting probe 34 is connected to the fiber 40 as described above, and is connected to a light source (not shown) provided in the optical system 70 via the fiber 40. When the light is emitted from the light source, the incident light L from the light source passes through the fiber 40 and enters the near-field light emission probe 34 as shown in FIG. Thereby, near-field light is emitted from the near-field light emission opening P of the probe 34.

FIG. 10 shows a state in which near-field light is emitted from the opening P of the fiber type near-field light emission probe 34. As shown in FIG. 10, the light L guided from the light source provided in the optical system 70 to the optical waveguide portion 36 a of the fiber type near-field light emission probe 34 via the fiber 40 is formed by the metal film 37. When the light passes through the opening P, the light becomes evanescent light E existing near the surface of the protruding exposed portion 38, the light intensity at the sharp portion of the protruded exposed portion 38 increases, and the narrowed light E 'is irradiated on the optical recording medium 10. can do.

The near-field light emitting probe of the coaxial shape shown in FIG. 8 also emits near-field light as described above. In this case, the light intensity of the sharp portion of the projecting exposed portion 38 is further increased. This is advantageous in irradiating the optical recording medium 10 with near-field light. In any case, near-field light is emitted from the near-field light emission opening P to the optical recording medium 10, whereby reflected light reflected from the medium 10 can be picked up by the opening P. As a result, the reflected light L ′ picked up by the opening P
Is transmitted through a fiber 40 as shown in FIG. 5 to a reproduction information detecting device (not shown) provided in the optical system 70 shown in FIG.

As described above, the optical system 70 shown in FIG. 1 has a light source and a reproduced information detecting device (not shown). The light source is connected to a near-field light emitting probe 34 via a fiber 40.
Incident on the optical recording medium 10 from the near-field light emission opening P.
The reflected light L ′ reflected from 0 and picked up at the opening P is converted into an electric signal, which can be detected as an information reproduction signal.

According to the information reproducing apparatus described above, when reproducing information from the optical recording medium 10 having the uneven texture 11 on the surface 10 ', the medium 10 is rotated in the direction A. When the medium 10 is rotationally driven, an air flow W is generated between the slider 30 and the optical recording medium 10 by the principle of air film lubrication, and the film of the air flow W causes the slider 30 to move a predetermined distance G from the optical recording medium 10. Floating optical recording medium surface 1
The distance between 0 ′ and the slider 30 or the near-field light emission opening P is kept constant (see FIG. 5). And the optical recording medium 10
The information recorded on the medium 10 is reproduced by irradiating the medium 10 with the near-field light from the near-field light emission opening P to pick up the reflected light reflected from the medium 10 at the opening P.

According to the information reproducing apparatus shown in FIG. 1 for carrying out the method for reproducing information from an optical recording medium according to the present invention, the diameter d of the near-field light exit opening of the slider 30 is determined by the uneven texture 11 of the optical recording medium 10. Since it is smaller than the arrangement pitch Tp,
Noise contained in the reflected light picked up by the opening P can be suppressed, and the S / N ratio of the information reproduction signal can be improved. When the optical recording medium having the tracking control guide groove 13a is adopted as the optical recording medium 10, the aperture diameter d is smaller than the width R of the guide groove 13a. When employing an optical recording medium having sample servo marks 13b for control, since the width is smaller than the width R of the marks 13b,
Noise contained in the reflected light picked up by the opening P can be suppressed, and the S / N ratio of the information reproduction signal can be improved.

As a result, it is possible to suppress occurrence of disturbance light (noise generation) at the time of information reproduction and to reproduce information with high accuracy. If the near-field light emission opening diameter d is too small, noise is suppressed, but due to the limitation due to the size of the opening diameter d,
The reflected light from the recorded information on the optical recording medium 10 is also hardly picked up. Therefore, the diameter d of the opening is, here, the optical recording medium 1.
The size is such that reflected light from recording information of 0 can be efficiently picked up.

The protruding exposed portion 38 of the near-field light emitting probe has a conical shape (fiber type shown in FIG. 7) or a truncated conical shape (coaxial shape shown in FIG. 8). The shape may be a pyramid such as a quadrangular pyramid or a hexagonal pyramid, or a truncated pyramid such as a truncated pyramid or a hexagonal pyramid. Next, an experiment for examining a state of noise included in an information reproduction signal at the time of information reproduction due to a difference in a near-field light emission opening diameter of the near-field light emission probe was performed.

In the experiment, the optical recording medium 10 was used as the optical recording medium.
In the optical recording medium in which the tracking guide 13 is not provided, that is, the uneven texture 11
And the optical recording medium 1 having recording pits 12 formed in advance.
OX was used in the information reproducing apparatus shown in FIG. In addition, a fiber type probe is adopted as the near-field light emitting probe 34 of the slider 30 in the information reproducing apparatus shown in FIG. 1, and the conditions of metal deposition of the metal film 37 are changed so that the near-field light emitting aperture diameter d is reduced. Experiments 1, 2, and 3 were performed using three different types of probes. That is, in the experimental example 1, the near-field light emission probe 34A having the near-field light emission opening having the opening diameter larger than the arrangement pitch Tp of the uneven texture 11 is used, and in the experimental example 2, the arrangement pitch of the uneven texture 11 is used. Tp
Experimental Example 3 uses the near-field light emission probe 34B having a smaller near-field light emission opening, and the diameter of the opening in Experimental Example 3 is reduced.
A near-field light emission probe 34C having a near-field light emission opening smaller than the near-field light emission opening diameter of the near-field light emission probe 34B used in the above was used.

FIGS. 11A, 11B and 11
(C) shows a state in which the near-field light emitting probes 34A, 34B, and 34C are arranged close to the optical recording medium 10X in Experimental Examples 1, 2, and 3, respectively. In addition,
Figure 11 (A) Medium d _1, FIG. 11 (B) middle d _2, FIG. 11
(C) In the figure, d ₃ is the near-field light emitting probe 34
A, 34B, 34C are the opening diameters.

The experimental conditions are as follows. That is, the diameter of the opening of the probe 34A in the experimental example 1: d ₁ = 0.4
μm (d ₁ > Tp) Diameter of opening of probe 34B in Experimental Example 2: d ₂ = 0.1
6 μm (d ₂ <Tp) Diameter of opening of probe 34C in Experimental Example 3: d ₃ = 0.0
8 μm (d ₃ ≪Tp) Array pitch of uneven texture 11: Tp = 0.3
μm Pit size of recording pit 12: 0.06 μm These three near-field light emission probes 34A, 34B, 34
1 is mounted on the slider 30, and in the information reproducing apparatus shown in FIG. 1, a signal for each frequency component (spectrum) decomposed by the Fourier transform of the electric signal waveform by the reflected light from the medium 10X in the information reproducing apparatus. The intensity was observed.

The experimental results are summarized below. EXPERIMENTAL EXAMPLE 1 EXPERIMENTAL EXAMPLE 2 EXPERIMENTAL EXAMPLE 3 Intensity of Reproduced Signal Component Strong Strong Weak Noise Component Intensity Strong Weak Weak S / N Ratio Small Large Small Signal component) is strongly detected,
The spectrum (noise component) at the arrangement pitch of the uneven texture 11 was hardly detected, and the S / N ratio was large.
On the other hand, in Experimental Example 1, in addition to the spectrum (information reproduction signal component) modulated by the recording pits 12, the spectrum (noise component) at the arrangement pitch of the uneven texture 11 is also strongly detected, and the S / N ratio is small. Was. In Experimental Example 3, although the noise component strongly detected in Example 1 was hardly detected, the spectrum modulated by the recording pits 12 (information reproduction signal component) also became weak, and S
The / N ratio was small.

As described above, the opening diameter of the near-field light emitting probe is made smaller than the arrangement pitch of the uneven texture within a range in which information reflected light from information recorded on the optical recording medium can be picked up (a size capable of picking up information reflected light). It was found that information could be reproduced well. The optical recording medium 10 shown in FIGS. 1 and 2 as an optical recording medium, that is, an uneven texture 11 on the surface 10 'and a guide groove 13a for tracking control is provided.
Alternatively, the tracking guide 13 (size R = 0.8 μm) of the sample servo mark 13b for tracking control
m) and a similar experiment was performed using an optical recording medium having recording pits 12 formed in advance, and similar results were obtained.

[0054]

As described above, according to the present invention, there is provided a method for reproducing information from an optical recording medium using near-field light, which suppresses the generation of disturbance light (noise generation) during information reproduction. It is possible to provide a method of reproducing information from an optical recording medium that can reproduce information with high accuracy.

According to the present invention, there is provided an apparatus for reproducing information from an optical recording medium using near-field light, wherein information can be reproduced with high precision by suppressing the generation of disturbance light (the occurrence of noise) during the reproduction of information. An apparatus for reproducing information from an optical recording medium can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a part of an example of an information reproducing apparatus for executing a method of reproducing information from an optical recording medium according to the present invention.

2A is a perspective view of the optical recording medium shown in FIG. 1, FIG. 2B is an enlarged plan view of a part of the optical recording medium, and FIG. FIG. 3 is a cross-sectional view of a part of the medium in a recording medium radial direction.

FIG. 3 is a diagram showing a part of a state in which a guide groove for tracking control is formed on the surface of the optical recording medium, and FIG.
Is a plan view and FIG. (B) is a sectional view thereof.

FIG. 4 is a diagram showing a part of a state in which a sample servo mark for tracking control is formed on the surface of the optical recording medium; FIG. 4A is a plan view thereof, and FIG.
Is a sectional view thereof.

FIG. 5 is an enlarged view of the slider shown in FIG. 1 and a peripheral portion thereof.

FIG. 6 is a perspective view of the slider shown in FIG. 1 as viewed obliquely from below.

FIG. 7A is a cross-sectional view of a part of the fiber type near-field light emitting probe before it is mounted on the slider, and FIG. 7B is a state in which the probe is mounted on the slider. FIG. 3 is a perspective view of the fiber type near-field light emitting probe of FIG.

FIG. 8A is a cross-sectional view of a part of a coaxial near-field light emitting probe before it is mounted on a slider, and FIG. 8B is a state in which the probe is mounted on the slider. FIG. 3 is a perspective view of a near-field light emitting probe having a coaxial shape of FIG.

FIG. 9A is a diagram for comparing the aperture diameter of a fiber type near-field light emitting probe with the arrangement pitch of uneven texture on an optical recording medium, and FIG. FIG. 7 is a diagram for comparing the aperture diameter of the field light emission probe with the arrangement pitch of the uneven texture on the optical recording medium.

FIG. 10 is a diagram showing a state in which near-field light is emitted from an opening of a fiber-type near-field light emission probe.

FIG. 11A is a diagram showing a state in which a near-field light emitting probe is arranged close to an optical recording medium in Experimental Example 1, and FIG. FIG. 7C is a diagram illustrating a state where the near-field light emitting probe is arranged in proximity to the optical recording medium in Experimental Example 3 in the third embodiment.

[Explanation of symbols]

Reference Signs List 10 optical recording medium 10 'surface of optical recording medium 10 10X optical recording medium 11 uneven texture 11a concave portion 11b convex portion 12 recording pit 13 tracking guide 131a tracking control guide groove 131b sample servo mark for tracking control 20 rotation drive device Rotation axis of 30 Slider 31 Slider surface 32 Hole for fitting fiber 33 Outlet side of air flow 34, 34A, 34B, 34C Near-field light emission probe 34 'Tip of near-field light emission probe 34 341 Core 342 Clad 34a 34b Probe 34a ', 34b' Tip of probe 35 Tip of optical fiber 36a 36a Optical fiber (optical waveguide made of dielectric) 36b Glass tube (optical waveguide made of dielectric) 37 Metal film 38 Near-field light emission Exposed exposed part of probe 3 Fine wire made of metal (Ag) 40 Optical fiber 41 End portion of fiber 40 50 Suspension 51 Connection portion of suspension 50 with radial driving device 60 52 Holding portion of suspension 50 for slider 30 60 Radial driving device 70 Optical system 100 Head Apparatus 200 Optical recording medium housing part d Near-field light emission opening diameter h Height difference between concave part 11a and convex part 11b E Evanescent light E near the surface of dielectric 36 E 'Focused light F Flying force G Slider 30 and light Distance from recording medium 10 L Light guided through optical waveguide 36a L 'Reflected light picked up at opening P P Near-field light emission opening R Tracking guide width Tp Arrangement pitch of uneven texture W Air flow

Claims (8)

[Claims] An information recorded on an optical recording medium having an uneven texture on its surface is floated by an air film lubrication principle by moving the information relative to the medium, and information is reproduced on the medium. For reproduction using a slider capable of irradiating near-field light for the, as the slider,
Using a slider having a near-field light emission opening for irradiating the optical recording medium with near-field light and having a diameter of the opening smaller than the arrangement pitch of the uneven texture, the near-field light is applied to the medium from the opening. A method for reproducing information from an optical recording medium, comprising detecting reflected light reflected from the medium by irradiation to reproduce information. 2. When the optical recording medium is an optical recording medium having a guide groove for tracking control, the slider has a near-field light emission opening diameter smaller than an arrangement pitch of the uneven texture, and 2. The method for reproducing information from an optical recording medium according to claim 1, wherein a slider smaller than the width of said tracking control guide groove is used. 3. When the optical recording medium is an optical recording medium having a mark for sample servo for tracking control, the diameter of the near-field light emission opening of the slider is an array of the irregular texture. 2. The method for reproducing information from an optical recording medium according to claim 1, wherein a slider smaller than the pitch and smaller than the width of the sample servo mark is used. 4. A near-field light emitting probe is mounted as the slider, and a tip of the probe for emitting near-field light covers an optical waveguide portion made of a dielectric and a side peripheral surface of the optical waveguide portion. And a part of the optical waveguide is projected and exposed as a near-field light emission opening in a cone shape or a frustum shape from the metal film. The method for reproducing information from an optical recording medium according to any one of claims 1 to 3, wherein the diameter of the near-field light emission opening is set. 5. The information recorded on an optical recording medium having an uneven texture on its surface is moved relative to the medium so that it floats by the principle of air film lubrication and reproduces information on the medium. A slider capable of irradiating near-field light for irradiating the optical recording medium with the near-field light from the slider, thereby detecting reflected light reflected from the medium and reproducing from the optical recording medium. An information reproducing apparatus, wherein the slider has a near-field light emission opening for irradiating the optical recording medium with near-field light, and the opening diameter is smaller than an arrangement pitch of the uneven texture. Information reproducing apparatus from an optical recording medium. 6. An apparatus for reproducing information from an optical recording medium having a guide groove for tracking control as the optical recording medium, wherein the diameter of the near-field light emission opening of the slider is an arrangement pitch of the uneven texture. 6. The information reproducing apparatus from an optical recording medium according to claim 5, which is smaller and smaller than the width of the tracking control guide groove. 7. An apparatus for reproducing information from an optical recording medium having a sample servo mark for tracking control as said optical recording medium, wherein said near-field light emission opening diameter of said slider is equal to said diameter. 6. The apparatus for reproducing information from an optical recording medium according to claim 5, wherein the pitch is smaller than the arrangement pitch of the uneven texture and smaller than the width of the sample servo mark. 8. The slider has a near-field light emitting probe mounted thereon, and the tip of the probe for emitting near-field light has an optical waveguide portion made of a dielectric and a side peripheral surface of the optical waveguide portion. It is made of a metal film to be coated, and a part of the optical waveguide is projected and exposed in a conical shape or a frustum shape from the metal film as a near-field light emission opening, and the bottom diameter of the projected exposed portion is The apparatus for reproducing information from an optical recording medium according to any one of claims 5 to 7, wherein the diameter of the near-field light emission opening is the same.