JP2001184691A - Recording medium, optical head and recording/ reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording medium in which the density of information recording can be increased and to provide an optical head and a recording and reproducing device to carry out recording or the like of the information on the recording medium. SOLUTION: The recording medium 9 has a plurality (two) of recording layers 92a, 92b laminated on a base member 91. At least one recording layer is a near field optical recording layer in which information recording or the like is carried out by the optical effect by using near field light. For example, both of the recording layers 92a, 92b can be formed as near field optical recording layers. The recording layers 92a, 92b are formed from photochromic materials M1, M2, respectively, having different optical characteristics relating to the wavelength dependence of the absorbance. The interference between the recording layers 92a, 92b can be avoided and recording and reproducing operation can be performed by using light of different wavelengths. Or, the recording layer 92b may be formed as a recording layer by propagating light (information recording or the like is performed by the optical effect by using the propagating light).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium capable of recording information at a high density, and an optical head and a recording / reproducing apparatus for recording / reproducing information on / from the recording medium.

[0002]

2. Description of the Related Art In recent years, the limit of high-density recording media (such as magnetic disks) using a recording method using optical action by ordinary propagating light has become apparent, and new high-density recording technology has been sought. ing. Above all, near-field optical recording is a technique capable of using light with a smaller spot diameter without being restricted by the diffraction limit of the wavelength to be used, and this can increase the density of information.

In such near-field optical recording, the size of recording pits is smaller than the wavelength of light to be used, and information is recorded and / or reproduced using a recording layer disposed near the surface of a recording medium. Will be

[0004]

However, in the recording medium for near-field optical recording as described above, only the vicinity of the surface is used, and there is room for increasing the density of the recording medium.

In a recording medium using only near-field light recording as described above, if there is no recording / reproducing apparatus using near-field light (near-field light recording / reproducing apparatus), recording is performed on the recording medium. It is impossible to access the information at all.

In view of the above problems, the present invention provides a recording medium capable of increasing the density of information recording, and an optical head and a recording / reproducing apparatus for recording / reproducing information on / from such a recording medium. The primary purpose is to provide.

It is a second object of the present invention to provide a recording medium capable of recording / reproducing information even when there is no near-field optical recording / reproducing apparatus.

[0008]

In order to achieve the above object, a recording medium according to claim 1 is a recording medium for recording information, comprising: a base member; and a base member laminated on the base member. A plurality of recording layers, wherein at least one of the plurality of recording layers is a near-field optical recording layer in which at least one of recording and reproduction of information is performed by an optical action using near-field light. There is a feature.

According to a second aspect of the present invention, in the recording medium according to the first aspect, an outermost layer of the plurality of recording layers is the near-field light recording layer.

A recording medium according to a third aspect of the present invention is the recording medium according to the second aspect, wherein a recording layer next to the outermost layer among the plurality of recording layers has a near-field optical characteristic of the outermost layer. It is a near-field optical recording layer different from the optical recording layer.

A recording medium according to a fourth aspect of the present invention is the recording medium according to any one of the first to third aspects, wherein at least one of the plurality of recording layers is an optical disc using propagation light. Characterized in that it is a propagated optical recording layer on which at least one of recording and reproduction of information is performed by a dynamic action.

A recording medium according to a fifth aspect is the recording medium according to any one of the first to fourth aspects, wherein the plurality of recording layers each have tracking information for each of the recording layers. It is characterized by having.

[0013] According to a sixth aspect of the present invention, in the recording medium according to any one of the first to fifth aspects, the plurality of recording layers are different from each other in optical characteristics with respect to wavelength dependence of absorbance. It is formed using a photochromic material.

An optical head according to a seventh aspect of the present invention is an optical head which has an optical effect on a recording medium on which a plurality of recording layers including at least one near-field optical recording layer are laminated, and has different wavelengths. A plurality of light sources that emit light; a wavelength selection determining unit that selects and determines a wavelength of light used for the optical action among light of a plurality of wavelengths emitted from the plurality of light sources; and the wavelength selection determination. An optical system for guiding light having a wavelength selected by the means to the recording medium.

The optical head according to the present invention is an optical head having an optical effect with a recording medium in which a plurality of recording layers including a near-field optical recording layer and a propagation optical recording layer are stacked. A light source that emits light, an optical system that includes a solid immersion lens and condenses light emitted from the light source, and a relative position changing unit that changes a focal position of the optical system and a relative position of the solid immersion lens. Wherein the relative position changing means adjusts the focal position to a predetermined position on the boundary surface of the solid immersion lens to apply the near-field light, and adjusts the focal position to a position other than the predetermined position to propagate the propagation light. It is characterized in that it is possible to selectively switch the state of operation.

According to a ninth aspect of the present invention, there is provided a recording / reproducing apparatus for performing at least one operation of recording and reproducing information on a recording medium having a plurality of recording layers stacked thereon. 8. An optical head according to claim 8, further comprising: a signal processing unit that processes a recording signal for the recording medium or a reproduction signal from the recording medium via the optical head.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <A. First Embodiment><Schematic Configuration of Recording / Reproducing Apparatus> FIGS. 1 and 2 are schematic diagrams showing the configuration of a recording / reproducing apparatus 1 (1A) according to a first embodiment of the present invention. The recording / reproducing apparatus 1 includes a rotation mechanism unit 5 that rotates the recording medium 9 in a predetermined direction while holding the recording medium 9 described later, an optical head 2 that records and reproduces a signal on and from a recording surface of the recording medium 9, A controller 3 for providing a drive control signal to the optical head 2 and the rotation mechanism 5, a recording signal for the recording medium 9, or a recording medium 9
And a signal processing unit 4 for processing a reproduction signal from the CPU.

The rotation mechanism section 5 includes a rotation drive section 51 and a rotation member 52. The rotation drive section 51 rotates the rotation member 52 in a predetermined direction based on a drive control signal supplied from the controller 3. The rotating member 52 has a structure for holding the detachable recording medium 9 at a predetermined position, and performs a rotating operation integrally with the loaded recording medium 9.

The optical head 2 includes a laser light source 11, a collimator lens 12, a beam splitter 13, a photodetector 14, an optical head driving unit 18, a holding member 19, and an optical system 20.

The laser light source 11 is configured to be driven by a laser drive circuit (not shown) provided in the controller 3. The light emitted from the laser light source 11 is guided to the recording medium 9 via the collimator lens 12, the beam splitter 13, and the optical system 20.

The collimator lens 12 has a function of converting light emitted from the laser light source 11 into parallel light, and the beam splitter 13 transmits parallel light guided from the collimator lens 12. The light transmitted through the beam splitter 13 is projected by the optical system 20 after forming a minute spot on the recording surface of the recording medium 9.

Here, the laser light source 11 has a plurality of (here, two) laser light sources 11a and 11b, and the collimator lens 12 has a plurality of (here, two) collimator lenses 12a and 12b. are doing. Further, the laser light sources 11a and 11b respectively have specific wavelengths λ1 and λ
2 light is emitted. Here, the first laser light source 11a
Ar emitting light of wavelength λ1 = 514.5 nm
(Ar) laser, and He− that emits light of wavelength λ2 = 632.8 nm is used as the second laser light source 11b.
An example in which a Ne (helium-neon) laser is used will be described. Light emitted from each of the laser light sources 11a and 11b is incident on and collimated by the collimator lenses 12a and 12b, respectively.

The optical head 2 further has a folding mirror 15 and a multiplexing prism 16. Laser light source 1
1a is incident on the collimator lens 12a and is collimated,
And proceeds to the beam splitter 13. On the other hand, the light emitted from the laser light source 11b enters the collimator lens 12b, is collimated, is reflected by the folding mirror 15, is also reflected by the multiplexing prism 16, and is transmitted to the beam splitter 13. move on.

The beam splitter 13 emits two beams emitted from two laser light sources 11a and 11b.
Only one type of light of the wavelengths λ1 and λ2, which is selectively determined to be used for an optical action with a recording medium described later, enters. This selection is determined by the controller 3.

After that, as described above, the light that has traveled to the beam splitter 13 passes through the beam splitter 13 and is projected by the optical system 20 after forming a minute spot on the recording surface of the recording medium 9.

On the other hand, the reflected light from the recording medium 9 travels in the opposite direction, and returns from the optical system 20 to the beam splitter 13. Then, after being reflected by the beam splitter 13, the light enters the photodetector 14. As a result, the information recorded on the recording medium 9 is read by the photodetector 14.

The laser light source 11, the collimator lens 12, the beam splitter 13 and the photodetector 14 are respectively arranged at predetermined positions, and the optical system 20 is
9 at the tip. The holding member 19 is configured to be able to advance and retreat in a straight line with respect to the rotation center direction of the recording medium 9 by the optical head driving unit 18. The controller 3 supplies a driving control signal to the optical head driving unit 18. The position of the holding member 19, that is, the optical system 2
The position of “0” with respect to the recording medium 9 is controlled. Note that the drive mechanism of the optical head 2 does not have to be configured to advance and retreat linearly with respect to the rotation center direction of the recording medium 9, but is a mechanism that swings the holding member having a predetermined length in the rotation center direction. You may.

The signal processing section 4 supplies data to be recorded on the recording medium 9 to the laser drive circuit via the controller 3, and sends the read data (reproduced data) detected by the photodetector 14 to the controller 3. Received via
It has the function of outputting to other data processing devices.

<Optical System 20> As shown in FIG.
The optical system 20 includes an objective lens 21 and a solid immersion lens (SIL:
Solid Immersion Lens) 22 and mirror 29. As a result, light that has traveled in the horizontal direction after passing through the beam splitter 13 is reflected by the mirror 29, and
The traveling direction is changed downward, and after being refracted and condensed by the objective lens 21, the light passes through the inside of the solid immersion lens 22 and is condensed (imaged) on the bottom surface of the solid immersion lens 22. This light condensed on the bottom surface of the solid immersion lens 22 oozes as near-field light, and is applied to the recording surface of the recording medium 9 which is present in the vicinity of a near-field region (a proximity region having a wavelength of ４ or less). ,
A small spot is formed and projected.

Here, the solid immersion lens 22 is made of a translucent material having a high refractive index. Specifically, as the solid immersion lens 22, a glass material such as SF6 can be used. By using the solid immersion lens 22 having such a high refractive index, the diameter (spot diameter) d (not shown) of the spot light focused on the bottom surface B can be miniaturized. This is understood from the fact that the spot diameter d of light can be expressed by the following equations (1) and (2).

[0031]

(Equation 1)

[0032]

(Equation 2)

Note that k is a constant, λ is the wavelength, and NA is the numerical aperture. Θ (see FIG. 2) is the half-opening angle, and n represents the refractive index of the medium (here, the solid immersion lens 22) that passes during light collection.

From the above equation (2), when the refractive index n of the solid immersion lens 22 has a large value (for example, a value relatively large with respect to the vacuum refractive index 1), the numerical aperture NA may be large. It can be seen from Equation 1 that a smaller spot diameter d can be obtained when having a large numerical aperture NA. That is, by condensing light in the solid immersion lens 22 having a high refractive index, a smaller spot diameter d can be realized.

Here, the optical system 20 is constituted by using the solid immersion lens 22, but as shown in FIG. 9, an objective lens 23 for condensing and a SNOM (Scanning Near-field Op
The optical system 20 may be configured by using a fiber probe 24 and a tical microscope. In this case, SNOM
The fiber probe 24 is connected to each of the laser light sources 11a and 11b.
Is emitted toward the recording medium 9 and, in a state close to the recording medium 9, generates near-field light that oozes from the front end thereof. Therefore, using this near-field light,
It becomes possible to perform a recording / reproducing operation of digital information on the recording medium 9.

<Recording Medium 9> FIG. 3 is a sectional view of the recording medium 9 (9A) according to the first embodiment. As shown in FIG. 3, the recording medium 9 (9A) includes a base member 91 and a plurality (here, two layers) of recording layers 92a and 92b laminated on the base member 91. Use).

The recording medium 9 further has tracking information for each of the recording layers 92a and 92b for each of the recording layers 92a and 92b. Specifically, as shown in the plan view of FIG. 4, a servo track information area RS is provided in a specific sector area of a recording area of the recording medium 9 having a disk-shaped outer shape, and tracking information is recorded. deep. The optical head 2 reads the tracking information when accessing the recording medium 9 and uses it for position control of the optical head 2.

According to this, a plurality of recording layers 92a, 92
b has tracking information for each of the recording layers 92a and 92b, respectively.
Can be controlled independently for each recording layer.

In this recording medium 9A, each recording layer 9
2a and 92b (FIG. 3) are near-field light recording layers in which at least one of information recording and reproduction is performed by optical action using near-field light, and is a recording layer formed of a photochromic material. is there.

More specifically, the recording layer 92a located at the position of the outermost layer (outermost layer) of the plurality of recording layers laminated on the base member 91 is formed by using the photochromic material M1. Formed as a 30 nm thick film,
The recording layer 92b located next to the recording layer 92a (position closer to the base member 91 than the recording layer 92a) is formed as a 30 nm thick film using the photochromic material M2. Here, 1,2-bis- (2,5-dimethylthiophene-3) is used as the photochromic material M1.
-Yl) perfluorocyclopentene, and 1,2-bis- (2-methyl-5- (4-biphenyl) thiophen-3-yl) perfluorocyclopentene as the photochromic material M2 (see FIG. 7). ).

<Recording / Reproducing Operation> In this near-field optical recording layer, digital information recording / reproducing operation and the like are performed by utilizing the change in the optical characteristics of the photochromic material before and after irradiation with light of a specific wavelength.

FIG. 5 is a diagram for explaining the state transition of the photochromic material. FIG. 6 shows the wavelength dependence of the absorbance (absorbance at each wavelength) of the photochromic material.
6 is a graph showing optical characteristics of the optical disk.

As shown in FIGS. 5 and 6, the photochromic material before and after irradiation with light of a specific wavelength
It has the property that its optical properties change. For example, before irradiating light of a specific wavelength λa, the curve L
When the photochromic material having the characteristic ST1 of the characteristic a1 (the two-dot chain line in FIG. 6) is irradiated with light having the specific wavelength λa, the photochromic material transitions to the state having the characteristic ST2 of the curve Lb (the solid line in FIG. 6). Furthermore, by irradiating light of wavelength λb different from wavelength λa,
The photochromic material transitions from the state having the property ST2 to the state having the property ST1 in the opposite direction.

Therefore, for example, by using the light having the wavelength λb as the erasing light, the photochromic material over the entire predetermined recording layer 92 of the recording medium 9 has the characteristic ST1 (curve La).
After initializing to have a different wavelength λ as the recording light
By irradiating the light of “a” only on a specific portion of the recording layer 92 of the recording medium 9, only the irradiated portion has the characteristic ST2
(Curve Lb). In this manner, in the recording layer 92 of the recording medium 9, by selectively forming a portion having the characteristic ST1 and a portion having the characteristic ST2, two states in digital storage, that is, "1" and "0". Can be expressed. Further, a separate wavelength λc (for example, 5
By irradiating light (at about 00 nm) and detecting different reflectances based on the difference in absorbance between the two states, it is possible to read these two states separately. In this way, it is possible to perform the operation of reproducing digital information composed of a combination of two-bit signals “1” and “0”.

Here, in the above description, it is assumed that the light of each wavelength λa, λb, λc is used in each of the recording operation, the erasing operation, and the reproducing operation.
The present invention is not limited to this. For example, the recording operation and the reproducing operation can be performed using light having the same wavelength (λa = λc), and the erasing operation can be performed using light having the wavelength λb. Hereinafter, the latter case, that is, the case where the recording operation and the reproducing operation are performed using light having the same wavelength (λa = λc) will be described.

As described above, in the recording medium 9 according to the present embodiment, two recording layers 92a and 92b are formed as near-field optical recording layers using two types of photochromic materials M1 and M2.

FIG. 7 shows two types of photochromic materials M.
It is a figure explaining the above-mentioned state transition about 1 and M2. The respective photochromic materials M1 and M2 use the wavelengths λ1 and λ2 as the wavelengths λa used for the recording operation and the reproduction operation, respectively, to change the state having the characteristic ST1 on the left side in the drawing from the characteristic ST2 on the right side in the drawing. Having the wavelength λb used for the erasing operation.
By using the wavelengths λ3 and λ4, respectively, from the state having the characteristic ST2 (right side in the figure) to the characteristic S
The state transits to a state having T1 (left side in the figure). Here, it is assumed that the erasing operation is not performed and the two wavelengths λ
1, λ2, two photochromic materials M1,
The case where the recording operation and the reproducing operation in M2 are performed will be described.

FIG. 8 shows each photochromic material M
6 is a graph showing optical characteristics of absorbance (wavelength dependence of absorbance) for each wavelength for 1 and M2. However, in FIG. 8, two photochromic materials M
1 and M2, those corresponding to the curve Lb representing the characteristic ST2 are represented as curves L1 and L2, respectively, and corresponding to the curve La (the two-dot chain line in FIG. 6) representing the characteristic ST1. Is not shown for simplicity. Note that the optical characteristics in the characteristic ST1 are in the wavelength region of reproduction light (the region including the wavelengths λ1 and λ2).
It has a value that is relatively much smaller than the absorbance represented by the curves L1 and L2 representing the characteristic ST2.

The recording layers 92a and 92b are respectively shown in FIG.
Photochromic material M having optical characteristics as shown in FIG.
1, M2.

The recording / reproducing operation is performed on the recording layer 92a using the light having the wavelength λ1 (= 514.5 nm). In this case, by using strong light for the recording operation and weak light for the reproducing operation, both operations (recording operation and reproducing operation) can be performed while using light of the same wavelength.
Can be realized separately.

For the recording layer 92b, the wavelength λ2
(= 632.8 nm) light is used to perform a recording / reproducing operation. Also in this case, strong light is used for the recording operation,
Moreover, by using weak light for the reproducing operation, both operations (recording operation and reproducing operation) can be realized while using light of the same wavelength.

First, regarding the recording operation, for each photochromic material M1 and M2, the corresponding wavelength λ1,
By partially irradiating the light of λ2 with a large intensity,
This is realized by causing the above-described state transition in the irradiated portion to have a state having the characteristic ST2.

On the other hand, with respect to the reproducing operation, for each photochromic material M1, M2, the corresponding wavelength λ1,
This is performed by irradiating light of λ2 with a small intensity and measuring the intensity of the reflected light. That is, the characteristic ST1 and the characteristic S
By dividing the intensity of the reflected light by a predetermined threshold based on the difference between the absorbance and the reflectance in the two states with T2, the two states "0" and "1" are separated and read as digital information. Can be played.

Here, since the light having the wavelength λ1 used for the reproducing operation of the recording layer 92a reaches the recording layer 92b and is reflected, the presence or absence of recording pits in the recording layer 92b (the state of the photochromic material M2 is determined by the characteristic ST2) Whether or not it has the characteristic ST1) affects the reflectance detected by the photodetector 14, but as shown in FIG. 8, the absorbance of the recording layer 92b (photochromic material M2) for the wavelength λ1 is 92a (photochromic material M
Since it has a relatively small value compared to the absorbance for the wavelength λ1 of 1), the influence on the detected reflectance is small, and if an appropriate threshold is set, the state of the photochromic material M1 of the recording layer 92a is (Characteristic ST1 or characteristic ST2) can be read separately.

As described above, since the absorbance of the photochromic material M1 at the wavelength λ1 is relatively larger than the absorbance of the photochromic material M2, the light of the wavelength λ1 is irradiated and the reflected light intensity is adjusted to an appropriate threshold value. Is determined by setting the recording layer 9b without being affected by the state of the photochromic material M2 of the recording layer 92b.
The state (the characteristic ST1 or the characteristic ST2) of the photochromic material M1 of 2a can be read separately.

The light of wavelength λ2 passes through the recording layer 92a, reaches the recording layer 92b, and is reflected.
Presence or absence of recording pits in 2a (whether the state of photochromic material M1 is characteristic ST2 or characteristic ST1)
Influences the reflectance detected by the photodetector 14, but as shown in FIG. 8, the absorbance of the recording layer 92a (photochromic material M1) for the wavelength λ2 is
2b (photochromic material M2) has a relatively small value compared to the absorbance at wavelength λ2,
The influence on the detected reflectance is small, and if an appropriate threshold value is set, the state of the photochromic material M2 (whether the characteristic ST1 or the characteristic ST2) of the recording layer 92b can be distinguished and read.

As described above, since the absorbance of the photochromic material M2 at the wavelength λ2 is relatively larger than the absorbance of the photochromic material M1, the light of the wavelength λ2 is irradiated and the reflected light intensity is adjusted to an appropriate threshold value. Is set, the recording layer 9a is not affected by the state of the photochromic material M1 of the recording layer 92a.
The state (the characteristic ST1 or the characteristic ST2) of the photochromic material M2 of 2b can be distinguished and read.

In particular, in this case, since the light having the wavelength λ2 is hardly absorbed by the recording layer 92a (photochromic material M1), the light is recorded on the recording layer 92b located below (inside) the recording layer 92a. A sufficient amount of light reaches to perform the reproducing operation. Further, since the thickness of the recording layer 92a is sufficiently small (sufficiently smaller than １ ／ of the wavelength λ2), the light having the wavelength λ2 reaches a position exceeding the thickness of the recording layer 92a as near-field light ( Leach out). Therefore, it is possible to favorably perform the recording / reproducing operation on the recording layer 92b located below the recording layer 92b.

In the above description, as the wavelengths λ1 and λ2 of light used for recording and reproduction, light having a wavelength λ1 shorter than the wavelength λ2 is used for the recording layer 92a on the front side, and the lower recording layer 92b is used for the lower recording layer 92b. On the other hand, light having a longer wavelength λ2 is used. As described above, this is preferable in that the difference in the absorbance between the photochromic materials M1 and M2 is used, but in view of the fact that the leaching depth of the near-field light depends on the wavelength. Is also preferred. In other words, near-field light using relatively long wavelength light can ooze to a deeper position than using relatively short wavelength light. Light having a relatively short wavelength λ1 is used for the near-field optical recording layer 92a (that is, a shallow layer), and light having a relatively long wavelength λ2 is used for the near-field optical recording layer 92b (that is, a deep layer) that is relatively far from the surface. By using light,
This ensures that the near-field light recording layer 92b (that is, a deep layer) that is relatively far from the surface can be accessed by optical action using near-field light. In addition,
When such an effect is not required, on the other hand, a relatively long wavelength λ2 is used for the recording layer 92a on the front side, and a relatively short wavelength λ2 is used for the lower recording layer 92b.
One light may be used.

As described above, since the recording layers 92a and 92b are formed by using the photochromic materials M1 and M2 having different optical characteristics with respect to the wavelength dependence of the absorbance, interference between the recording layers is avoided. And at least one of recording and reproduction of information. In particular, by selectively using the two wavelengths λ1 and λ2 by utilizing the difference in the optical characteristics of the recording layers 92a and 92b, the recording layers 92a and 92b stacked in the vertical direction can be selectively used. Can be accessed.

As described above, since the recording medium 9A includes a plurality of near-field light recording layers 92a and 92b as recording layers, it is possible to increase the density of information recording by increasing the number of recording layers.

In the above description, the outermost recording layer 92a of the plurality of recording layers is the near-field light recording layer.
As described above, since the near-field optical recording layer having the optical action using the near-field light whose light amount is weak compared with the propagating light is provided on the outermost layer, the reduction in the signal-to-noise ratio of the signal is suppressed, At least one of recording and reproduction of information can be performed more reliably.

Further, in the above, since the recording layer 92b next to the outermost layer among the plurality of recording layers is also a near-field light recording layer, the density of information recording can be further increased.

According to the optical head 2 and the recording / reproducing apparatus 1 using the optical head 2, a plurality of recording layers 92 are provided.
By selectively using a plurality of wavelengths λ1 and λ2 for a and 92b, it is possible to perform a recording / reproducing operation on a recording medium 9 having a plurality of recording layers 92a and 92b.

In the above description, the case where two near-field optical recording layers 92a and 92b are provided as a plurality of recording layers has been described. However, the present invention is not limited to this, and three or more near-field optical recording layers are provided. It may be something. In that case,
The material of each recording layer, the wavelength used for recording / reproduction (and the corresponding light source), and the like are determined in consideration of the optical characteristics related to the wavelength dependence of the absorbance of each recording layer.

<B. Second Embodiment> In the first embodiment, the outermost recording layer 92a of the plurality of recording layers 92a and 92b stacked on the base member 91 is described.
And the recording layer 92 located next to the recording layer 92a.
In the second embodiment, the near-field optical recording layer is provided on the outermost layer, but the recording layer below is provided on the lower recording layer in the second embodiment. A recording medium 9B provided with a propagating light recording layer on which at least one of information recording and reproduction is performed by an optical action using normal light that is not near-field light, that is, propagating light will be described.

FIG. 10 is a schematic diagram showing the configuration of a recording / reproducing apparatus 1B according to the second embodiment. Recording / reproducing device 1B
Has the same configuration as that of the recording / reproducing apparatus 1A except for the components other than the optical head 2, that is, the controller 3, the signal processing unit 4, the rotation mechanism unit 5, and the like.

The optical head 2B can be roughly classified into an optical head 2Ba for near-field light and an optical head 2B for propagating light.
b) and two systems of optical heads.

The near-field light optical head 2Ba includes a laser light source 11a, a collimator lens 12a, and a beam splitter 1.
3a, a photodetector 14a, an optical system 20a, and the like. Here, a case where an SNOM fiber probe is used as the optical system 20a is illustrated. This SNO
A small opening having a predetermined size (for example, a diameter of 100 nm) is provided at the tip of the M-fiber probe, and a size corresponding to the small opening (for example, about 100 nm).
nm) can ooze out.

The propagating optical head 2Bb includes a laser light source 11b, a collimator lens 12b, a beam splitter 13b, a photodetector 14b, an optical system 20b, and the like. Further, the optical system 20b does not have a solid immersion lens, and the light collected by the objective lens 21b is directly
An image is formed on the recording medium 9B to form a spot light.
This spot light is relatively larger than the spot light formed by the above-described near-field light optical head 2Ba. For example, the light having a wavelength of λ2 = 632.8 nm is converted to a numerical aperture NA (in vacuum). The light is condensed using the objective lens 21b = 0.6, so that it is formed as having a size of about 1 μm. This is the optical head 2 for near-field light.
It is about ten times as large as the spot light formed in Ba.

As the laser light sources 11a and 11b, the first
The same laser as in the embodiment is used, and the laser light source 11a emits light with a wavelength λ1 = 514.5 nm, and the second laser light source 11b emits light with a wavelength λ2 = 632.8 nm.

FIG. 11 is a sectional view of the recording medium 9B. As shown in FIG. 11, the recording medium 9B includes a base member 91 and a plurality of (here, two layers) recording layers 92Ba and 92Bb stacked on the base member 91.
Specifically, the recording layer 92Ba is made of a photochromic material M
1 and the recording layer 92Bb is formed using the photochromic material M2. However, while the recording layer 92Ba is formed as a film having a thickness of 30 nm, the recording layer 9Ba is formed.
2Bb is formed as a film having a larger thickness, for example, 100 nm.

In the near-field light optical head 2Ba (FIG. 10) of the recording / reproducing apparatus 1B, the light having the wavelength λ1 seeps in accordance with the size of the minute opening provided at the tip. For example, a spot light having a diameter of about 100 nm infiltrates the recording medium 9B through a small aperture of about 100 nm provided at the tip of the SNOM fiber probe 24. The near-field light optical head 2Ba uses at least the near-field light leached in this manner to perform at least recording and reproduction with respect to the recording layer 92Ba located on the most surface side among the recording layers of the recording medium 9B. One operation can be performed.

In the propagating optical head 2Bb, the light of wavelength λ2 is condensed by the objective lens 21b, and a spot light is formed on the recording medium 9B. For example, a spot light having a size of about 1.3 μm can be formed using an objective lens having a numerical aperture NA = 0.6. The propagating light optical head 2Bb exerts an optical action on the recording medium 9B using the spot light (propagating light) thus formed, thereby recording and recording on the recording layer 92Bb of the recording medium 9B. At least one operation of reproduction can be performed.

Therefore, similarly to the first embodiment, the difference between the optical characteristics of the recording layers 92Ba and 92Bb is utilized to make use of the difference.
By selectively using the two wavelengths λ1 and λ2, each of the recording layers 92Ba and 92Bb stacked in the vertical direction can be accessed.

As described above, according to the recording medium 9B, in addition to the near-field light recording layer 92Ba, at least one of information recording and reproduction is performed by the optical action using propagating light as the plurality of recording layers 92. Propagation optical recording layer 92B to be performed
Since b is also provided, it is possible to increase the density of information recording. Further, even when there is no near-field optical recording / reproducing device, at least one of information recording and reproducing can be performed on the propagating optical recording layer 92Bb by optical action using propagating light. The possibility of access to the recording medium 9B can be left. In particular, if part of the information recorded in the near-field light recording layer 92Ba is also recorded in the propagation light recording layer 92Bb in an overlapping manner, even if there is no near-field light recording / reproducing device, the propagation Optical recording layer 9
The same information can be obtained by reading out the information recorded in 2Bb by a recording / reproducing device for propagating light.
Alternatively, by recording an overview of information included in the entire recording medium 9B in the propagation optical recording layer 92Bb,
It can also be used as an index.

As in the first embodiment, each recording layer 92
Since Ba and 92Bb are formed using the photochromic materials 1 and M2 having different optical characteristics with respect to the wavelength dependence of the absorbance, it is possible to avoid interference between the recording layers. In addition to this, the size of the spot light used for recording / reproducing of the propagation light recording layer 92Bb is very much smaller than the size of the spot light used for recording / reproducing of the near-field light recording layer 92Ba (here, about Since it is large, the recording / reproducing operation of the propagation optical recording layer 92Bb is less affected by the state of the near-field optical recording layer 92Ba.

<C. Third Embodiment> In the recording / reproducing apparatus 1B of the second embodiment, when performing a recording / reproducing operation using near-field light and propagating light, etc., the optical head 2Ba for near-field light and the optical head 2Bb for propagating light are used. Although the optical head 2B having two systems is provided, this third embodiment relates to a case where two types of light (near-field light and propagation light) are applied to a recording medium by one system of optical head. explain.

The recording / reproducing apparatus 1C according to the third embodiment
The recording medium 9C (see FIG. 11) used in the second embodiment has two recording layers, a near-field light recording layer 92Ba and a propagation light recording layer 92Bb, as in the second embodiment.

The recording / reproducing apparatus 1C has the same components as those of the recording / reproducing apparatus 1A (see FIG. 1) except for the components other than the optical head, that is, the controller 3, the signal processing section 4, the rotating mechanism section 5, and the like. It has. Further, the recording / reproducing apparatus 1C also includes an optical head 2C, and has the same configuration as the optical head 2A of the first embodiment, except for the optical system 20C.

FIG. 12 is a diagram showing an outline of the optical system 20C. As shown in FIG. 12, the optical system 20C includes an objective lens 21C and a solid immersion lens 22C. Here, the solid immersion lens 22C has an optical axis A as described later.
It differs from the first embodiment in that it is configured to be able to move in a plane perpendicular to C. Thereby, the relative position between the focal position P by the optical system 20C and the solid immersion lens 22C is changed.

More specifically, the state shown in FIG. 12A and the state shown in FIG. 12B are switched by the movement of the solid immersion lens 22C.

FIG. 12A shows a state in which near-field light is applied to the recording medium 9 with the focal position P being adjusted to the center position CP on the boundary surface (bottom surface) B of the solid immersion lens 22C. . In this state, the light refracted and condensed by the objective lens 21C passes through the inside of the solid immersion lens 22C located at the position C1, and passes through the center position C of the bottom surface B of the solid immersion lens 22C.
The light is condensed (imaged) at P. Then, the solid immersion lens 22
This light condensed (imaged) at the central position CP of the bottom surface B of C is leached as near-field light, and forms a minute spot on the recording surface of the recording medium 9C existing near the near-field region. And projected. For example, the minute spot emits light of wavelength λ1 with a numerical aperture NA (in vacuum).
The light is condensed by an objective lens 21C of 0.6, passes through a solid immersion lens having a refractive index of 1.7, and forms an image on its bottom surface, whereby it can be generated as having a size of about 615 nm.

On the other hand, FIG. 12B shows a boundary surface (bottom surface) B
A state is shown in which the focal position P is adjusted to a position other than the upper central position CP so that the propagating light acts on the recording medium 9. The solid immersion lens 22C moves in a direction parallel to the surface of the recording medium 9C (a direction perpendicular to the optical axis AC) and is at a position C2. Therefore, since the solid immersion lens 22C is not located at the condensing position of the objective lens 21C,
The light refracted and condensed at C does not pass through the solid immersion lens 22C, but is condensed (imaged) near the surface of the recording medium 9C as it is. Therefore, since the effect of decreasing the spot diameter with the increase in the numerical aperture NA as described above cannot be obtained, a spot light having a small diameter as shown in FIG. (For example, about 1.3 μm) is formed on the recording medium 9C. Note that this large spot light is formed using light of wavelength λ2.

As described above, the relative positional relationship between the objective lens 21C and the solid immersion lens 22C is changed so that the focal position P
And the solid immersion lens 22C, the focal position P is shifted to the center position CP on the boundary surface of the solid immersion lens.
(Hereinafter, also referred to as “near-field light generation state”, refer to FIG. 12A), and the focal position P is adjusted to a position other than the center position CP to apply the propagation light. State (hereinafter, also referred to as “near-field light non-generation state”,
12 (see FIG. 12B). As a result, a near-field light generating layer is generated on the near-field light recording layer 92Ba of the recording medium 9C, and a recording / reproducing operation or the like is performed using an optical action using the near-field light. For the optical recording layer 92Bb, a recording / reproducing operation or the like can be performed by using an optical action using a propagation light by generating a near-field light non-generation state.

FIGS. 13 and 14 are a top view and a side view showing a driving mechanism of the solid immersion lens 22C. Here, a case where the solid immersion lens 22C is driven by an impact driving method using a piezo element will be exemplified.
This impact drive system is a drive system in which the horizontal displacement is increased to a value exceeding the displacement amount of the piezo element itself by causing a small displacement of the piezo element with a small displacement accompanied by a frictional sliding operation.

The drive mechanism of the solid immersion lens 22C includes two sliding mechanisms F and a holder 28 that holds the solid immersion lens 22C between the two sliding mechanisms F. The sliding mechanism F includes a piezo element 25, a rod 26, and a bearing 2
7a and a housing 27b.

One end of the piezo element 25 is fixedly connected to the housing 27b, and the other end is fixedly connected to the rod 26. Further, the rod 26 has two bearings 2
7a slidably supported by the piezoelectric element 2
5 moves in the axial direction of the rod 26 in accordance with the expansion and contraction in the axial direction. The holder portion 28 has an elongated hole portion 28b into which the rod 26 is inserted, and the elongated hole portion 28b and the rod 2
6 is slidably in contact with appropriate friction.

In such a mechanism, rapid deformation of the piezo element 25 is used. Specifically, in a state where the solid immersion lens 22C is at the position C1, the piezo element 25 is slowly contracted and then rapidly expanded. According to this, at the time of low-speed contraction, the rod 26 and the holder 28 are integrally moved (therefore the solid immersion lens 22C) by the static frictional force between the long hole 28b and the rod 26, and are moved in the direction of the arrow AR. On the other hand, at the time of high-speed extension, the long hole 28b and the rod 26 move relative to each other (slip) due to rapid operation.
The rod 26 moves in the direction opposite to the arrow AR with respect to the holder 28, and the holder 28
It will move in the direction of R. Along with this, the solid immersion lens 22C held by the holder 28 also moves by a predetermined amount in the direction of the arrow AR. By repeating both the contraction and extension operations, the solid immersion lens 22C held by the holder unit 28 can be moved in the direction of the arrow AR by a horizontal movement distance exceeding the displacement of the piezo element itself.

Further, by reversing the operation at the time of contraction and the operation at the time of extension (ie, low-speed extension and high-speed contraction), the solid immersion lens 22C can be moved in the reverse direction of the arrow AR. It is.

With such a driving mechanism, the solid immersion lens 2
2C can be moved in a plane perpendicular to the optical axis AC.

According to the optical head 2C of the third embodiment, two types of light (near-field light and propagating light) can act on the recording medium by one system of optical head. , A compact optical head can be constructed.

<D. Fourth Embodiment> In the third embodiment, the relative position between the focal position of the optical system and the solid immersion lens is changed by relatively moving the solid immersion lens in a direction perpendicular to the optical axis. In the fourth embodiment, a case will be described in which the relative position between the focal position of the optical system and the solid immersion lens is changed by relatively moving the solid immersion lens in the optical axis direction.

The fourth embodiment is a modification of the third embodiment, and the recording / reproducing apparatus 1D, optical head 2D, optical system 20D, recording medium 9D, etc. according to the fourth embodiment correspond to those of the third embodiment. It has the same configuration as the element. The following description focuses on the differences.

FIG. 15 is a diagram showing an outline of the optical system 20D. As shown in FIG. 15, the optical system 20D includes an objective lens 21D and a solid immersion lens 22D. Here, the objective lens 21D is held by a holder 28d, and the solid immersion lens 22D is held by a holder 28e. The holder 28d and the holder 28e are connected by a piezo element 25, and the solid immersion lens 22
It is configured such that D can be moved with respect to the objective lens 21 in the optical axis AC direction. This allows
The relative position between the focal position and the solid immersion lens is changed.

Specifically, by moving the solid immersion lens 22C in the optical axis direction, the state of FIG. 16A and the state of FIG.
State is switched.

FIG. 16A shows a state in which the near-field light is applied to the recording medium 9 with the focal position P being adjusted to the center position CP on the boundary surface (bottom surface) B of the solid immersion lens 22D. . In this state, the light refracted and condensed by the objective lens 21D passes through the inside of the solid immersion lens 22D located at the position D1, and the center position C of the bottom surface B of the solid immersion lens 22D.
The light is condensed (imaged) at P. Then, the solid immersion lens 22
This light condensed (imaged) at the center position CP of the bottom surface B of D oozes out as near-field light and forms a minute spot on the recording surface of the recording medium 9D existing near the near-field region. And projected.

On the other hand, FIG. 16B shows the boundary (bottom) surface B
A state is shown in which the focal position P is adjusted to a position other than the upper central position CP so that the propagating light acts on the recording medium 9. The solid immersion lens 22D moves the recording medium 9D from the position D1.
Moves in a direction perpendicular to the surface (in the direction of the optical axis AC) away from the recording medium 9D, and is in a position D2. Therefore, the focal position P does not exist on the bottom surface B of the solid immersion lens 22D, but is focused (imaged) near the surface of the recording medium 9C as it is. Therefore, since the effect of decreasing the spot diameter with the increase in the numerical aperture NA as described above cannot be obtained, a spot light having a small diameter as shown in FIG. Is formed on the recording medium 9D. In this case, since an aberration due to passing through the solid immersion lens 22D is added,
The spot light has a larger diameter (for example, about 1.5 μm) than that of the third embodiment (see FIG. 12B).

As described above, the relative position between the objective lens 21D and the solid immersion lens 22D in the direction of the optical axis AC is changed to change the relative position between the focal position P and the solid immersion lens 22D. A state in which the near-field light is applied by adjusting the focal position P to the center position CP on the boundary surface of the immersion lens (near-field light generating state), and the propagation light is applied by adjusting the focal position P to a position other than the center position CP (A state in which no near-field light is generated). This allows
For the near-field light recording layer 92Ba of the recording medium 9D, a near-field light generation state is generated, and a recording / reproducing operation or the like is performed by using an optical action using the near-field light, so that the propagating light recording layer of the recording medium 9D is formed. For 92Bb, a recording / reproducing operation or the like can be performed using an optical action using a propagation light by generating a near-field light non-generation state.

Here, the relative position between the focal position P and the solid immersion lens 22D is changed by moving the solid immersion lens 22D in the direction of the optical axis AC to change the relative positional relationship between the objective lens and the solid immersion lens 22D. However, the focus position P and the solid immersion lens are changed by moving the objective lens 21D in the optical axis AC direction to change the positional relationship between the objective lens 21D and the solid immersion lens 22D. The position relative to 22D may be changed.

<E. Fifth Embodiment> In the third and fourth embodiments, the relative position between the focal position P and the solid immersion lens 22D is changed by changing the positional relationship between the objective lens and the solid immersion lens. , But is not limited to this. In the fifth embodiment, a case where the relative position between the focal position and the solid immersion lens is changed by changing the relative positional relationship between the collimator lens and the light source will be described.

The fifth embodiment is different from the third embodiment and the fourth embodiment.
This is a modification of the embodiment, and is a recording / reproducing apparatus 1E, an optical head 2E, an optical system 20E, and a recording medium 9E according to the fifth embodiment.
And the like have the same configuration as the corresponding elements of the third embodiment and the fourth embodiment. The following description focuses on the differences.

Specifically, by moving the collimator lens 12 (12a, 12b) in the direction of the optical axis A as shown in FIG. 17, the state shown in FIG. 18A and the state shown in FIG.
Alternatively, the state is switched to the state shown in FIG. More specifically, the holder for holding the collimator lens 12 is
Any mechanism may be used as long as it moves in the direction, and a ball screw mechanism, a mechanism using the above-described piezo element, or the like can be used.

FIG. 18A shows a state where near-field light is applied to the recording medium 9E with the focal position P being adjusted on the boundary surface (bottom surface) B of the solid immersion lens 22E. In this state, the collimated light collimated by the collimator lens 12 is incident on the objective lens 21E, is refracted and condensed by the objective lens 21E, passes through the inside of the solid immersion lens 22E, and passes through the bottom of the solid immersion lens 22E. Central position CP of B
Converge (image). Then, the solid immersion lens 22E
This light condensed (imaged) at the center position CP of the bottom surface B of the recording medium 9E leaches as near-field light, and forms a minute spot on the recording surface of the recording medium 9E existing close to the near-field area. Projected. In addition, this minute spot light is
It is formed using light of wavelength λ1.

On the other hand, FIG. 18B shows a boundary surface (bottom surface) B
A state is shown in which the focal position P is adjusted to a position other than the upper center position CP (a position lower than the position CP), and the propagating light acts on the recording medium 9E. This state is realized as follows. First, by slightly moving the collimator lens 12 in the direction of the optical axis A in a direction approaching the laser light source 11, light emitted through the collimator lens 12 is converted into non-collimated light. Then, the non-collimator light, whose light flux gradually spreads, is incident on the objective lens 21E, so that it can be focused (imaged) at a position below the position CP.

FIG. 18C shows a boundary surface (bottom surface) B
A state is shown in which the focal position P is adjusted to a position other than the upper center position CP (a position above the position CP), and the propagating light acts on the recording medium 9E. This state is realized by the operation opposite to the above. First, by slightly moving the collimator lens 12 in a direction away from the laser light source 11 in the direction of the optical axis A, light emitted through the collimator lens 12 is made non-collimated light.
Then, the non-collimator light whose light flux is gradually narrowed is made incident on the objective lens 21E, so that it can be condensed (imaged) at a position above the position CP.

Here, FIG. 18B or FIG.
8 (c), the numerical aperture NA as described above
Since the effect of decreasing the spot diameter cannot be obtained with the increase of the spot light, the spot light does not have a very small diameter as shown in FIG. 12A, but has a larger diameter (for example, about 1.5 μm). The spot light is recorded on the recording medium 9E.
Formed. Note that this large spot light
It is formed using light of wavelength λ2.

As described above, by changing the relative positional relationship between the collimator lens 12 and the laser light source 11 and changing the relative position between the focal position P and the solid immersion lens 22E, the bottom surface B of the solid immersion lens 22E is changed. A state in which the near-field light is applied by adjusting the focal position P to the upper central position CP (near-field light generating state), and the propagation light is applied by adjusting the focal position P to a position other than the bottom surface B of the solid immersion lens 22E. The state (near-field light non-generation state) is selectively switched. This allows
With respect to the near-field light recording layer 92Ba of the recording medium 9E, a near-field light generation state is generated, and a recording / reproducing operation or the like is performed by using an optical action using the near-field light, and the propagation light recording layer of the recording medium 9E is formed. For 92Bb, a recording / reproducing operation or the like can be performed using an optical action using a propagation light by generating a near-field light non-generation state.

According to the fifth embodiment, although a mechanism for moving the collimator lens 12 is required,
There is no need to move the small solid immersion lens to change the positional relationship between the objective lens and the solid immersion lens. Therefore, since a mechanism for moving the small solid immersion lens is not required, two types of spot lights can be obtained with a simple configuration.

In the fifth embodiment, the near-field light generating state is generated by making the collimated light incident on the objective lens, and the near-field light non-generating state is generated by making the non-collimated light incident on the objective lens. However, the reverse is also possible.
That is, the near-field light generating state may be generated by making the collimated light incident on the objective lens, and the near-field light generating state may be generated by making the non-collimated light incident on the objective lens.

Further, it is not necessary to use collimated light,
The near-field light generating state and the near-field light non-generating state may be generated by selectively using the two states of the non-collimated light.

<F. Others> In the optical heads of the third to fifth embodiments, when accessing the near-field optical recording layer and the propagation optical recording layer, recording is performed by changing the relationship between the solid immersion lens and the focal position. Although the size of the spot light formed on the medium was changed, as shown in FIG. 19, a plurality of filters having wavelength selectivity (wavelength selection filters) were used to meet the desired spot diameter. It is formed as a minute portion having a size, and by selectively passing light of a specific wavelength in the minute portion, the size of the spot light formed on the recording medium is changed according to the wavelength. Is also good.

FIG. 19 is a diagram showing the tip of the optical system (the portion close to the recording medium 9) in such an optical head. 19A is a sectional view, and FIG. 19B is a top view. As shown in the figure, the distal end of this optical system has a structure in which a filter portion 61 is provided at the center of a thin plate-shaped non-translucent member 63. In the filter section 61, an annular second filter 61b having an outer diameter d2 (d1 <d2) is provided so as to surround the circular first filter 61a having a diameter d1.

The first filter 61a has an optical characteristic of transmitting both the light of the wavelength λ1 and the light of the wavelength λ2. The second filter 61b allows the light of the wavelength λ2 to pass and the light of the wavelength λ1. It has optical characteristics of blocking light.

Accordingly, since the light having the wavelength λ1 passes through the first filter 61a but does not pass through the second filter 61b, when the light having the wavelength λ1 is incident on the filter section 61, the spot light having the diameter d1 is recorded. Formed in the medium 9.

Since the light having the wavelength λ2 passes through both the first filter 61 and the second filter 61b, when the light having the wavelength λ2 is incident on the filter section 61, the spot light having the diameter d2 becomes a recording medium. 9 is formed.

As described above, it is possible to obtain a spot light having two sizes (diameters d1 and d2) according to the wavelengths λ1 and λ2, so that the lights having the two wavelengths λ1 and λ2 are respectively transmitted to the recording medium 9D. By acting on the near-field optical recording layer and the propagating optical recording layer, a recording / reproducing operation or the like in each recording layer can be performed.

It should be noted that such a filter unit 61
It may be provided at the tip of the OM fiber probe.

In each of the above embodiments, the recording medium has a circular shape. However, the present invention is not limited to this. The recording medium may have a rectangular shape such as a card type.

[0120]

As described above, according to the recording medium of the first aspect, the near-field optical recording layer in which at least one of recording and reproduction of information is performed by an optical action using near-field light is included. Since a plurality of recording layers are provided, it is possible to increase the density of information recording.

In particular, according to the recording medium of the present invention, a near-field light recording layer having an optical action using near-field light whose light intensity is weaker than that of propagating light is provided on the outermost layer. Therefore, it is possible to suppress a decrease in the SN ratio of the signal and more reliably perform at least one of recording and reproduction of information.

According to the recording medium of the third aspect, the next recording layer next to the outermost layer among the plurality of recording layers has near-field light whose optical characteristics are different from those of the near-field light recording layer as the outermost layer. Since it is a recording layer, it is possible to further increase the density of information recording.

According to the recording medium of the fourth aspect, in addition to the near-field light recording layer, at least one of information recording and reproduction is performed by optical action using propagating light. Since it also includes a propagation optical recording layer to be performed, it is possible to increase the density of information recording. Further, even when there is no near-field optical recording / reproducing device, at least one of information recording and reproducing can be performed on the propagating optical recording layer by optical action using propagating light, The possibility of access to this recording medium can be left.

According to the recording medium of the present invention, each of the plurality of recording layers has tracking information for each recording layer. The position can be controlled independently for each recording layer.

Furthermore, according to the recording medium of the present invention, since the plurality of recording layers are formed using photochromic materials having different optical characteristics with respect to the wavelength dependence of the absorbance, respectively. Interference can be avoided, and at least one of recording and reproduction of information can be performed.

According to the optical head of the seventh aspect, by selectively using a plurality of wavelengths for a plurality of recording layers, a plurality of recording layers including at least one near-field optical recording layer can be formed. By exerting an optical effect with the laminated recording medium, a recording / reproducing operation can be performed on a recording medium having a plurality of recording layers.

Further, according to the optical head of the present invention, a light source for emitting light, an optical system including a solid immersion lens for condensing light emitted from the light source, and a focal position of the optical system are fixed. A relative position changing means for changing a relative position with respect to the immersion lens, wherein the relative position changing means adjusts the focal position to a near-field light generating position which is a predetermined position on a boundary surface of the solid immersion lens, It is possible to selectively switch between a state where the focal position is adjusted to a position other than the predetermined position. That is, in a recording medium in which a plurality of recording layers including a near-field optical recording layer and a propagating optical recording layer are stacked, an optical field using near-field light is used for each of the near-field optical recording layer and the propagating optical recording layer. Therefore, it is possible to selectively switch between the optical action and the optical action using the propagating light for access, so that a compact optical head can be configured.

According to the recording / reproducing apparatus of the ninth aspect, the same effects as those of the seventh or eighth aspect can be obtained.

[Brief description of the drawings]

FIG. 1 is a recording and reproducing apparatus 1A according to a first embodiment of the present invention.
FIG. 3 is a schematic diagram showing the configuration of FIG.

FIG. 2 is a side view showing the configuration of the optical system 20.

FIG. 3 is a sectional view of a recording medium 9A.

FIG. 4 is a plan view of a recording medium 9A.

FIG. 5 is a diagram illustrating a state transition of a photochromic material.

FIG. 6 shows a photochromic material having characteristics ST1,
It is a figure which shows the light absorbency (wavelength dependence of light absorbency) with respect to each wavelength in every state which has ST2.

FIG. 7 is a diagram showing a state transition of the photochromic materials M1 and M2.

FIG. 8 shows each photochromic material M1 and M2.
It is a graph which shows the optical characteristic showing the light absorbency with respect to each wavelength.

FIG. 9 is a diagram showing a modification of the optical system 20.

FIG. 10 is a schematic diagram illustrating a configuration of a recording / reproducing device 1B according to a second embodiment.

FIG. 11 is a sectional view of a recording medium 9B.

FIG. 12 is a diagram showing an outline of an optical system 20C.

FIG. 13 is a top view illustrating a driving mechanism of a solid immersion lens 22C.

FIG. 14 is a side view illustrating a driving mechanism of a solid immersion lens 22C.

FIG. 15 is a cross-sectional view illustrating a configuration of an optical system 20D.

FIG. 16 is a sectional view showing the operation of the optical system 20D.

FIG. 17 is a schematic diagram showing a configuration of an optical head 2E.

FIG. 18 is a cross-sectional view showing a convergence operation in the optical system 20E.

FIG. 19 is a diagram showing a tip portion of an optical head provided with a wavelength selection filter.

[Explanation of symbols]

 1, 1A-1E recording / reproducing device 2, 2A-2E optical head 3 controller 4 signal processing unit 5 rotation mechanism unit 9, 9A-9E recording medium 11, 11a, 11b laser light source 12, 12a, 12b collimator lens 14 photodetector 20, 20a, 20b, 20C to 20E Optical system 21, 21b, 21C to 21E, 23 Objective lens 22, 22C to 22E Solid immersion lens 24 SNOM fiber probe 91 Base member 92a, 92b, 92Ba Near-field optical recording layer 92Bb Propagating light Recording layer F Sliding mechanism M1, M2 Photochromic material P Focus position RS Servo track information area

Continued on the front page (72) Inventor Yujiro Suzuki 2-3-1-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka F-term in Osaka International Building Minolta Co., Ltd. 5D029 HA06 HA07 JA04 JB02 JB04 JB05 JB08 JB41 JB46 JB47 JB48 JC03 MA04 VA03 5D118 AA26 BA01 BB02 BC13 BF02 BF03 CA11 CA13 CD06 CG03 CG07 CG16 CG26 DC02 DC05 EA11 5D119 AA41 BA01 BB06 CA16 DA01 DA05 EB02 EB07 EB15 EC20 EC44 EC45 EC47 FA08 JA44 JA49 JC07

Claims (9)

[Claims] 1. A recording medium for recording information, comprising: a base member; and a plurality of recording layers laminated on the base member, wherein at least one recording layer of the plurality of recording layers is provided. Is a near-field light recording layer in which at least one of recording and reproduction of information is performed by an optical action using near-field light. 2. The recording medium according to claim 1, wherein an outermost layer of the plurality of recording layers is the near-field light recording layer. 3. The near-field optical recording layer according to claim 2, wherein the next recording layer next to the outermost layer among the plurality of recording layers has optical characteristics different from those of the near-field optical recording layer of the outermost layer. A recording medium characterized by being an optical recording layer. 4. The recording medium according to claim 1, wherein at least one of the plurality of recording layers records and reproduces information by an optical action using propagating light. Wherein the recording medium is a propagation light recording layer on which at least one of the following is performed. 5. The recording medium according to claim 1, wherein each of the plurality of recording layers has tracking information for each of the recording layers. Medium. 6. The recording medium according to claim 1, wherein each of the plurality of recording layers is formed using a photochromic material having optical characteristics different from each other in wavelength dependence of absorbance. A recording medium characterized by the above-mentioned. 7. An optical head having an optical effect on a recording medium on which a plurality of recording layers including at least one near-field optical recording layer are stacked, wherein the plurality of light sources emit light of different wavelengths from each other. Of the light of a plurality of wavelengths emitted from the plurality of light sources,
A wavelength selection determining unit that selects and determines the wavelength of light used for the optical action; and an optical system that guides the light of the wavelength selected by the wavelength selection determining unit to the recording medium. And the optical head. 8. An optical head having an optical effect with a recording medium on which a plurality of recording layers including a near-field optical recording layer and a propagating optical recording layer are stacked, wherein: a light source for emitting light; An optical system for condensing light emitted from the light source, and a relative position changing unit for changing a relative position between a focal position of the optical system and the solid immersion lens, wherein the relative position changing unit includes: A state where the near-field light is applied by adjusting the focal position to a predetermined position on the boundary surface of the solid immersion lens, and a state where the propagation light is applied by adjusting the focal position to a position other than the predetermined position. An optical head characterized by being switchable. 9. A recording / reproducing apparatus which performs at least one operation of recording and reproducing information on a recording medium on which a plurality of recording layers are stacked, wherein the optical head according to claim 7 or 8; A recording / reproducing apparatus, comprising: a signal processing unit that processes a recording signal for the recording medium or a reproduction signal from the recording medium via an optical head.