JP2002230817A - Information recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the stability and the reliability of reproduced information in reproducing of information in an information recording and reproducing device. SOLUTION: A light shielding member 38 is arrange in the optical path of a light beam reflected on a recording medium 8, between a solid immersion mirror 1 and an optical detector 37, the luminous flux of the reflected light is transformed into a ring-belt shaped light. Namely, the device is so composed that the ring-belt shaped light L21 is detected in the optical detection process and when the light beam for reproducing information is entered to the solid immersion mirror 1, the light beam is made incident in such a state as a light beam L1 including the ring-belt region which is nearly the same as the ring-belt region used in the optical detection process, or a region inside the ring-belt region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording / reproducing apparatus for recording or reproducing information using light.

[0002]

2. Description of the Related Art In recent years, high-density optical recording using near-field light has been studied and developed with the increase in the density of recorded information by optical recording. In an optical head of an information recording / reproducing apparatus for performing recording or reproduction by generating near-field light, a solid immersion lens (S
IL: Solid Immersion Lens and solid immersion mirror (SIM:
Use of an optical element called a solid immersion mirror, which is made of a high-refractive-index substance, has been studied. In such an optical head, an optical element such as a solid immersion lens or a solid immersion mirror is incorporated in a holding member such as a slider, and the lowermost part of the optical element is floated at a position of several tens nm from the recording medium, and the optical element is optically driven. The light beam is condensed near the surface of the element to form a minute spot, and near-field light is leached from the minute spot to perform high-density information recording or information reproduction by the minute spot. You.

Normally, when a minute spot is formed on a solid immersion lens or a solid immersion mirror, a minute spot is formed by condensing all the light beams at a focusing position. In order to form a finer light spot in the optical element described above, the numerical aperture NA is large (for example, NA
It is effective to use only light of the component ≧ 1). This is because, by condensing only the light component having a large numerical aperture NA at the light condensing position, the near-field light can be more locally leached.

For this reason, in order to use only light of a component having a relatively large numerical aperture NA (NA ≧ 1) out of the total light flux, a solid immersion lens or a solid immersion mirror has an annular shape corresponding to the outer edge portion of the total light flux. It is desirable that only light of the above type be incident.

The near-field light is irregularly reflected by the recording layer, and the reflected light is incident again on a solid immersion lens or the like. The reflected light that has entered the solid immersion lens or the like follows the same optical path in the opposite direction as when irradiating light for information reproduction, and is then guided to a predetermined photodetector, which reproduces information. Will be done.

[0006]

However, in the case where the reflected light reflected from the recording medium is detected by the photodetector, if the total light flux of the reflected light is detected, the light beam having the reproduction information is only provided at the outer edge portion. , The SN ratio is very small. For this reason, there is a problem that it is difficult to reproduce information recorded on a recording medium at high density with high accuracy and stability.

[0007] Focusing on the light intensity, the light intensity shows a so-called Gaussian distribution in which the central portion of the total luminous flux is highest and decreases toward the outer edge portion. For this reason, even if near-field light is generated using only the light at the outer edge portion, which is a component having a large numerical aperture NA (for example, NA ≧ 1), the intensity is very weak. When the information recorded on the recording medium is reproduced by detecting the reflected light of the near-field light, the intensity of the reflected light is also weak, which causes a problem that the stability and reliability of the reproduced information are reduced.

Therefore, the present invention has been made in view of the above problems, and has as its object to improve the stability and reliability of reproduced information when reproducing information in an information recording / reproducing apparatus.

[0009]

In order to achieve the above object, according to the present invention, a recording medium is irradiated with light for reproducing information, and reflected light from the recording medium is received. An information recording / reproducing apparatus for reproducing information by irradiating the recording medium by inputting the irradiation light and irradiating the recording medium with a light source that generates irradiation light for the information reproduction. And an optical element for inputting reflected light from the recording medium, detecting means for detecting the reflected light incident on the optical element and reproducing information recorded on the recording medium, and the optical element and the optical element. And an orbicular light generating means disposed in an optical path of the reflected light between the detecting means and the reflected light to convert the luminous flux of the reflected light into an orbicular shape to make the reflected light into orbicular light.

According to a second aspect of the present invention, in the information recording / reproducing apparatus according to the first aspect, the irradiation light is converted into a light beam including an inner area of the annular shape and input to the optical element. Is done.

According to a third aspect of the present invention, in the information recording / reproducing apparatus according to the second aspect, the luminous flux of the irradiation light is constituted by the annular area and the annular inner area. You.

According to a fourth aspect of the present invention, in the information recording / reproducing apparatus according to the second aspect, the luminous flux of the irradiation light is constituted by an area inside the annular zone.

According to a fifth aspect of the present invention, in the information recording / reproducing apparatus according to the first aspect, the irradiation light is converted into a light flux composed of the annular zone and input to the optical element. .

[0014] The invention according to claim 6 is the invention according to claims 1 to 5.
The information recording / reproducing apparatus according to any one of the above, wherein the optical element is a solid immersion lens or a solid immersion mirror.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

<1. First Embodiment> First, a first embodiment of the present invention will be described. FIG. 1 is a diagram showing an information recording / reproducing apparatus 100 using a solid immersion mirror 1.

The information recording / reproducing apparatus 100 includes an optical head 3
0 and the recording medium 8, and irradiates the recording medium 8 with light for information reproduction from the optical head unit 30.
The information recorded on the recording medium 8 is reproduced by detecting the reflected light from the recording medium 8. Note that the recording medium 8 may be a medium built in the information recording / reproducing apparatus 100 so as to be difficult to remove, or a removable medium replaceable to the information recording / reproducing apparatus 100. There may be.

The optical head unit 30 has a laser light source 31 for irradiating light for information reproduction, converts the light for information reproduction from the laser light source 31 into parallel light, and shields a central portion of the light beam to form an annular band. A lens 32 for generating parallel light, a polarizing beam splitter 34, a quarter-wave plate 35, a solid immersion mirror 1 for generating near-field light for information reproduction and giving it to the recording medium 8, and a condenser lens 36. , A photodetector 37.

The laser light source 31 is composed of a semiconductor laser or the like, and generates information reproducing light for reproducing information recorded on the recording medium 8. The laser light emitted from the laser light source 31 is converted into parallel light by the lens 32, and the light beam cross section is converted into the first annular shape by the light shielding film 33 formed on one surface of the lens 32. Light shielding film 3
Reference numeral 3 may be any as long as it has a function of blocking light from the laser light source 31, and is made of, for example, an Al film whose surface is blackened.

The annular light (orbicular light) refers to light in a state where there is no light at the center of the light beam cross section, and has a circular or elliptical light beam cross section, for example. Light having a substantially constant width and having light in a circumferentially continuous area corresponds to the light. However, the cross section of the light beam may be a shape in which the circular shape or the elliptical shape is slightly distorted, or the light may be present in a state where it is partially interrupted in the outer peripheral direction.

By converting the light from the laser light source 31 to annular light by the lens 32, the near-field light can be more locally leached from the solid immersion mirror 1 to the recording medium 8 side. Recording pits formed on the recording medium 8 can be appropriately detected.

The light in the form of an orb is applied to the polarizing beam splitter 3.
4 is incident. The polarization beam splitter 34 has a function of transmitting a P wave and reflecting an S wave. The light transmitted through the polarizing beam splitter 34 transmits through the quarter-wave plate 35,
It becomes circularly polarized light. Then, the circularly polarized annular light enters the solid immersion mirror 1 which is an optical element arranged to face the recording medium 8 in order to guide the annular light to the recording layer of the recording medium 8.

FIG. 2 is a view showing an example of the solid immersion mirror 1. The solid immersion mirror 1 has a main body 10 made of a high refractive index material such as lanthanum silica glass or lead silica glass, and a first surface 11 on the upper surface side of the main body 10 is formed in a substantially planar shape. The second surface 12 on the lower surface side is formed in a paraboloid of revolution. A reflection film 13 for reflecting light inside the solid immersion mirror 1 is formed at the center of the first surface 11. The solid immersion mirror 1 is provided on the outer edge of the second surface 12 except for the central portion (that is, the portion near the focal position where self-focusing is performed).
Is formed with a reflective film 14 for reflecting light inside. The reflection films 13 and 14 are made of Al, Au, Ag, Cu, N
It is formed by a known thin film technique such as a sputtering method using a metal material such as i.

When laser light L1, which is an annular parallel light, is vertically incident on the first surface 11 of the solid immersion mirror 1 from the upper side as shown by an arrow in the figure, the incident light is rotated by a paraboloid of revolution. The light is reflected by the reflection film 14 on the two surfaces 12 and further enters the first surface 11 at a predetermined incident angle. The outer light component of the laser light L1 is reflected by the second surface 12 and then enters the first surface 11 at an angle that satisfies the condition of total reflection, and is totally reflected. The inner light component of the laser light L1 is the second light component.
Reflection film 1 formed on first surface 11 after reflection on surface 12
Reflects at 3. Therefore, the light reflected by the second surface 12 is
The light is reflected by the first surface 11 and collected near the center of the second surface 12.

In this manner, the annular light incident on the solid immersion mirror 1 is condensed on the substantially central portion of the second surface 12, and the light spot is smaller than the spot formed in the air. It becomes a spot and becomes a light spot smaller than the wavelength of light. Then, from the second surface 12 of the solid immersion mirror 1, the near-field light 9 of the minute light spot oozes downward. When the near-field light 9 reaches the recording layer 8a of the recording medium 8, information can be reproduced by detecting the reflected light from the recording medium 8.

The recording medium 8 is a disk-shaped surface recording type recording medium having a recording layer 8a formed on the front surface side. In brief, a tracking pattern for tracking control is formed on a substrate 8c made of glass, plastic, or the like. A tracking layer 8b is formed, and a recording layer 8a for recording information is formed thereon as an upper layer.

For example, the tracking layer 8b may be configured such that regions having different optical characteristics such as reflectivity are formed concentrically at regular intervals, or a predetermined layer is formed on the upper surface of a layer body (tracking layer 8b) formed of a predetermined material. It can be configured by forming an uneven pattern or the like. The substrate 8c of the recording medium 8 can be made of glass, and the recording layer 8a can be made of a material in which diarylethene, which is a photochromic material, is dispersed in PMMA. The thickness of the recording layer 8a is about 100 nm
It is. As the tracking pattern, a groove-shaped pattern formed by sputtering Al can be used.

In such a recording medium 8, near-field light 9 oozing from the lowermost portion of the solid immersion mirror 1 by the information reproducing laser beam (zonal light) L 1 incident on the solid immersion mirror 1 is applied to the recording medium 8. 8 so that information can be recorded by changing the optical characteristics of the photochromic material when the recording layer 8a reaches the recording layer 8a, and the information can be reproduced by reading the optical characteristics of the photochromic material. Is done. At the time of tracking, a tracking pattern is read.

In particular, in the case of information reproduction, the near-field light 9 is irregularly reflected when it reaches the recording layer 8a, and the light that re-enters the solid immersion mirror 1 among the reflected light is detected to reproduce the information. Done.

As shown in FIG. 2, the recording layer 8 of the recording medium 8
The reflected light reflected at a enters the bottom surface of the solid immersion mirror 1 and travels in the opposite direction along the same optical path as the laser light L1 from the laser light source 31. The reflected light from the recording medium 8 is reflected by the first surface 11 and the second surface 12 of the solid immersion mirror 1 and exits from the first surface 11 of the solid immersion mirror 1, and the light beam cross section has a first annular shape. The detection light L2 has substantially the same shape.

The detection light L2 is converted from circularly polarized light to S-polarized light when passing through the quarter-wave plate 35 as shown in FIG. 1, and is reflected by the polarization beam splitter 34.

The detection light L is applied to the polarization beam splitter 34.
A light-shielding member 38 for shielding the central portion of the light-emitting element 2 is provided. The light-blocking member 38 is disposed in the optical path of the detection light L2 between the solid immersion mirror 1 as an optical element and the photodetector 37 as a detection means, and converts the light flux of the detection light into an annular shape to thereby detect the detection light. It functions as an orbicular zone light generation unit that uses L2 as orbicular zone light L21. The light shielding member 38 is realized by forming a light shielding film such as an Al film on one surface of the polarization beam splitter 34. The light L22 (see FIG. 2) in the central part of the detection light L2 reflected by the polarization beam splitter 34 is shielded by the light blocking member 38, and the light traveling toward the photodetector 37 is included in the detection light L2. The second corresponding to the outer edge
Only the annular light L21. The second annular shape forming the light beam cross section of the light L21 is formed so as to be only an outer edge portion of the first annular shape indicated by the light beam cross section of the laser light L1. Then, the second annular light L21 is
It is configured to be condensed by the condenser lens 36 and detected by the photodetector 37.

The photodetector 37 is composed of a two-division or four-division photodiode or the like, and an electric signal based on the total amount of light received by a plurality of light-receiving parts formed by two-division or four-division is used as a reproduction signal. Becomes In addition, since the amount of light received by each light receiving unit changes according to a change in the relative position of the near-field light 9 with respect to the tracking pattern, tracking control can be performed by determining the ratio of the amount of light received by each light receiving unit.

In the information recording / reproducing apparatus 100,
The recording medium 8 is configured to be rotated by a rotation driving mechanism (not shown), and the optical head unit 30 can be moved to an arbitrary position from the center to the outer edge of the recording medium 8 by an optical head driving mechanism (not shown). The optical head unit 30 can reproduce information at an arbitrary position on the recording medium 8 or can record information at an arbitrary position on the recording medium 8.

Next, an operation of reproducing information recorded on the recording medium 8 in the information recording / reproducing apparatus 100 configured as described above will be described.

The laser light source 31 is configured to emit, for example, a laser beam having a wavelength of 635 nm as information reproducing light, and the information reproducing light output from the laser light source 31 passes through the lens 32 to form a first ring. The light L1 is a band light.

When the annular light L1 enters the solid immersion mirror 1, the component of the near-field light 9 that oozes out from the lowermost part of the solid immersion mirror 1 toward the recording medium 8 increases. For example, numerical aperture NA
In the case of the ring-shaped light L1 such that ≧ 1, almost 100% of the light L1 for information reproduction is the near-field light 9.

On the other hand, the light intensity in the cross section of the light beam has a Gaussian distribution in which the light beam center position is generally strongest and becomes weaker toward the outer edge. When the near-field light 9 is generated using the orbicular zone light L1 having a low light intensity corresponding to the outer edge portion of such a light intensity distribution, the light intensity of the near-field light 9 also decreases. If the light intensity of the near-field light 9 that permeates from the solid immersion mirror 1 becomes weak, the detection light L2 that becomes reflected light of the near-field light 9
Of course, the light intensity becomes weak, and stable information reproduction becomes difficult.

Therefore, in this embodiment, in order to make the light intensity of the near-field light 9 sufficient, the zone width is larger in the inward direction of the zone than the zone shape in which the component of the near-field light 9 is generated to the maximum. The light beam cross section of the laser beam L1 is formed so as to have an annular shape (first annular shape) in which is set to be large. Thereby, the light intensity of the near-field light 9 applied to the recording medium 8 for information reproduction can be made sufficient.

The near-field light 9 leaching from the solid immersion mirror 1 in this manner enters the recording layer 8a of the recording medium 8 and is reflected at the interface between the recording layer 8a and the tracking layer 8b. A recording pattern corresponding to information is formed on the recording layer 8a, and reflected light modulated by the recording pattern enters the solid immersion mirror 1 from the second surface 12 of the solid immersion mirror 1.

At this time, the reflected light incident on the solid immersion mirror 1 at a relatively large angle is reflected on the first surface 1 of the solid immersion mirror 1.
After being totally reflected at 1, the light is reflected by the reflective film 14 on the second surface 12 and travels in the opposite direction on the same optical path as the information reproducing light L1. The reflected light incident on the solid immersion mirror 1 at a relatively small angle is reflected by the reflection film 13 provided on the first surface 11 of the solid immersion mirror 1 and then reflected by the reflection film 14 on the second surface 12. The light is reflected and travels in the opposite direction on the same optical path as the information reproducing light L1.

The detection light L2 is reflected by the polarization beam splitter 34 in the direction where the photodetector 37 is located.
The photodetector 37 generates a reproduction signal by detecting the light component L21 of the orbicular zone (second orbicular zone) among the light components included in the detection light L2.

Generally, the light L21 in the annular zone is detected by the photodetector 3
7, the main lobe component of the light at the light condensing position becomes sharper than when the light L22 in the area inside the annular zone is also condensed. Therefore, the photodetector 37 can detect a reproduction signal with high resolution from the detection light L2.

That is, of the light L2 reflected by the polarization beam splitter 34, the light component L22 in the central portion thereof is shielded by the light shielding member 38, and the light component traveling to the photodetector 37 is detected inside the annular zone of the detection light L2. The reflected light modulated by the information recorded on the recording medium 8 can be detected with higher resolution by using the second annular light L21 in which the hollow region is further enlarged. .

When the light L1 for information reproduction is incident on the solid immersion mirror 1 in the information recording / reproducing device 100, the light L21 in the form of a ring detected by the photodetector 37 is used as a reference.
The first zonal laser light L1 having a light component not only in the annular zone of the annular zone of the light L21 but also in the zone inside the annular zone is incident on the solid immersion mirror 1. Therefore, the light intensity of the near-field light 9 that permeates from the bottom surface side of the solid immersion mirror 1 for information reproduction can be sufficiently increased.

Therefore, in the information recording / reproducing apparatus 100 of this embodiment, the near-field light 9 for information reproduction can be appropriately generated, and the information recorded on the recording medium 8 can be detected with high resolution. This makes it possible to improve the stability and reliability of the reproduced information at the time of reproducing the information.

Next, an operation of recording information on the recording medium 8 in the information recording / reproducing apparatus 100 configured as described above will be described.

When recording information, the information recording light emitted from the laser light source 31 or another light source different from the laser light source 31 is converted into annular recording light by the lens 32, and the recording light is converted into the light. Is incident on the solid immersion mirror 1 in the same manner as in the case of reproduction to generate near-field light 9 for recording. Information can be recorded by forming a desired recording pattern on the recording layer 8a of the recording medium 8 with the near-field light.

Here, if a heat mode recording medium such as a phase change material is used as the recording medium 8, a heat threshold exists due to the characteristics of the recording medium. In other words, the so-called pen tip recording can be performed only by recording, and it is possible to record a recording pit having a size smaller than the spot diameter of the near-field light 9.

Therefore, even when information is recorded by the information recording / reproducing apparatus 100, the information recording light from the light source can be applied to the minute area of the recording medium 8, and the recording of about 100 nm or less can be performed. Pits (recording patterns) can be recorded on the recording layer 8a, and high-density recording on the recording medium 8 becomes possible.

Next, a description will be given of a tracking operation when information is reproduced or recorded on the recording medium 8 in the information recording / reproducing apparatus 100 configured as described above.

When reproducing information, since the light for information reproduction from the laser light source 31 is constantly emitted, tracking can be performed using the light for information reproduction. In this case, the light L1 for information reproduction also functions as light for tracking.

On the other hand, when recording information, the information recording light is controlled to be turned on / off in accordance with the contents of the recording, so that it is difficult to perform tracking using the information recording light. . Therefore, when the information recording / reproducing apparatus 100 performs not only the reproduction of information but also the recording of information, it is desirable to separately provide a tracking light source. In this case, the light from the tracking light source is appropriately provided in the optical system. Is incident on the solid immersion mirror 1.

Such tracking light is guided to the solid immersion mirror 1 as in the case of reproducing or recording information.
A minute light spot is formed near the center of the second surface 12 of the solid immersion mirror 1, and near-field light of the minute spot is generated near the center of the second surface 12 of the solid immersion mirror 1.

The near-field light reaches the surface of the convex portion of the groove of the tracking layer 8b, and is reflected by, for example, an Al film. The depth of the unevenness is set so that the near-field light does not reach the concave portion of the tracking layer 8b.

The light reflected by the convex portion of the tracking layer 8b is detected by the photodetector 37 along the same optical path as in the case of information reproduction. Depending on the ratio of the amount of reflected light detected on each light receiving surface divided into two or four, the near-field light 9 for information reproduction or information recording is relatively different from the tracking pattern. The optical head unit driving mechanism can move the optical head unit 30 relative to the recording medium 8 so that tracking control can be appropriately performed.

<2. Second Preferred Embodiment> Next, a second preferred embodiment of the present invention will be described. FIG. 3 is a diagram showing an information recording / reproducing apparatus 200 using the solid immersion lens 2.

The information recording / reproducing apparatus 200 includes an optical head 4
0 and the recording medium 8, and irradiates the recording medium 8 with light for information reproduction from the optical head unit 40.
The information recorded on the recording medium 8 is reproduced by detecting the reflected light from the recording medium 8. The recording medium 8 is the same as that described in the first embodiment.

The optical head section 40 includes a laser light source 41 for irradiating light for information reproduction and a lens 4 such as a collimator lens.
2, a ring-shaped mirror 43 for reflecting the reflected light from the recording medium 8, a condenser lens 44, and a solid immersion lens 2 for generating the near-field light 9 for information reproduction and giving it to the recording medium 8.
, A condenser lens 46, and a photodetector 47.

The laser light source 41 is constituted by a semiconductor laser or the like, and generates information reproducing light for reproducing information recorded on the recording medium 8. The laser light L3 emitted from the laser light source 41 is converted into parallel light by the lens 42 and passes through an opening formed in the center of the ring-shaped mirror 43. The ring-shaped mirror 43 is used for light L for information reproduction.
3 is arranged in a state of being inclined at a predetermined angle in the optical path.

The laser light L 3 is condensed by the condenser lens 44, and thereafter enters the solid immersion lens 2, which is an optical element arranged to face the recording medium 8.

FIG. 4 is a view showing an example of the solid immersion lens 2. The solid immersion lens 2 is formed as a substantially hemispherical body 20 from a high refractive index material such as lanthanum silica glass or lead silica glass, and has a spherical portion 21 formed in a substantially spherical shape and a flat portion formed in a substantially planar shape. 22.

The laser light L 3 from the laser light source 41 is condensed by the condensing lens 44,
Incident on. The light incident on the solid immersion lens 2 is
Is condensed at a substantially central portion of the flat surface portion 22 of FIG. The light spot at this condensing position is a minute light spot compared to a spot formed in the air, and forms a spot smaller than the wavelength of light. As a result, the plane portion 2 of the solid immersion lens 2
From the vicinity of the center position of 2, the near-field light 9 of the minute light spot leaks downward. When the near-field light 9 reaches the recording layer 8 a of the recording medium 8, the near-field light 9 exhibits a reflection action corresponding to the recording pits of the recording layer 8 a, and the information can be reproduced by detecting the reflected light from the recording medium 8. Become.

In the case of information reproduction, the near-field light 9 is irregularly reflected when it reaches the recording layer 8a, and the light that re-enters the plane portion 22 of the solid immersion lens 2 out of the reflected light is detected. Information is reproduced.

As shown in FIG. 4, the recording layer 8 of the recording medium 8
The reflected light reflected at a includes not only light L42 having a small numerical aperture NA but also light L41 having a relatively large numerical aperture NA. In general, light L41 having a relatively large numerical aperture NA contains more high-frequency components than light L42. For this reason, even when only the circular laser beam L3 having a constant light beam width is incident on the solid immersion lens 2 as the information reproducing light, the recording medium 8 can be used.
The detection light L4 reflected not only includes the light component L42 that is the same as the light beam width of the laser light L3, but also includes the light component L41 in a region outside the light beam width. This detection light L4
Travels in the optical path of the information reproducing light L3 in the reverse direction.

Then, the detection light L4 is transmitted to the condenser lens 4
4, only the light component L <b> 41 at the outer edge is reflected by the ring-shaped mirror 43. With this ring-shaped mirror 43, of the detection light L4 from the solid immersion lens 2,
Only the second annular light L41 corresponding to the outer edge portion is reflected toward the photodetector 47, and the light incident on the photodetector 47 can be converted into annular light. That is, the ring-shaped mirror 43 is disposed in the optical path of the detection light L4 between the solid immersion lens 2 as an optical element and the photodetector 47 as detection means, and converts the light flux of the detection light L4 into an annular shape. In this way, the detection light L4 functions as an orbicular light generation unit that converts the detection light L4 into an orbicular light L41. The orbicular shape forming the light beam cross section of the orbicular light L41 is formed so as to include an outer portion of the light beam cross section of the laser light L3. The annular light L41 is configured to be condensed by the condensing lens 46 and detected by the photodetector 47. The photodetector 47 generates a reproduced signal by performing photoelectric conversion.

As in the first embodiment, the photodetector 47 is composed of a two-division or four-division photodiode or the like.
An electric signal based on the sum of the amounts of received light detected by the plurality of light receiving units formed by dividing into two or four is a reproduction signal. The amount of light received by each light receiving unit is used for tracking control.

In the information recording / reproducing apparatus 200,
The recording medium 8 is configured to be rotated by a rotation driving mechanism (not shown), and the optical head unit 40 can be moved to an arbitrary position from the center to the outer edge of the recording medium 8 by an optical head driving mechanism (not shown). The configuration is the same as that of the first embodiment.

Next, an operation of reproducing information recorded on the recording medium 8 in the information recording / reproducing apparatus 200 configured as described above will be described.

The laser light source 41 is configured to emit, for example, a laser beam L3 having a wavelength of 635 nm as information reproducing light. After the information reproducing light output from the laser light source 41 passes through the lens 42, Through the central opening, and is condensed by the condensing lens 44 to enter the solid immersion lens 2. Then, near-field light 9 permeates toward the recording medium 8 from the lowermost part of the solid immersion lens 2.

The near-field light 9 from the solid immersion lens 2 enters the recording layer 8a of the recording medium 8, and is reflected at the interface between the recording layer 8a and the tracking layer 8b. The reflected light modulated by the recording pits (recording pattern) of the recording layer 8a enters the solid immersion lens 2 from the plane portion 22 of the solid immersion lens 2.

At this time, the reflected light L42 incident on the solid immersion lens 2 at a relatively small angle is the information reproducing light L3.
Travel in the opposite direction along the same optical path as The reflected light L41 incident on the solid immersion lens 2 at a relatively large angle
Becomes an annular light passing outside the light beam of the information reproducing light L3, and travels in the opposite direction to the information reproducing light L3.

The light component L at the outer edge of the detection light L4
Only the light 41 is reflected by the ring-shaped mirror 43, becomes an annular light, is detected by the photodetector 47, and a reproduced signal is generated.

When the light L41 in the annular zone is condensed on the photodetector 47, the main lobe component of the light at the condensing position is compared with the case where the light L42 in the area inside the annular zone is also collected. Becomes sharper. Therefore, the photodetector 47 can detect a reproduction signal with high resolution from the detection light L4.

That is, of the detection light L 4 incident on the solid immersion lens 2, the light component L 42 at the center thereof is detected by the photo detector 4.
The light component L in the annular zone is not reflected in the direction where
By reflecting only 41 toward the photodetector 47, the reflected light modulated by the information recorded on the recording medium 8 can be detected with higher resolution.

When the light L3 for information reproduction is incident on the solid immersion lens 2 in the information recording / reproducing apparatus 200, the laser light L3 having a substantially circular light beam cross-section is not converted into a ring-shaped light, but the solid immersion lens 2 is used as it is. 2. For this reason, the light intensity of the near-field light 9 leaching from the solid immersion lens 2 is increased as compared with the case where annular light is incident, and the reflected light intensity from the recording medium 8 can be increased.

Therefore, the information recording / reproducing apparatus 100 of this embodiment can appropriately generate the near-field light 9 for information reproduction and detect the information recorded on the recording medium 8 with high resolution. This makes it possible to improve the stability and reliability of the reproduced information at the time of reproducing the information.

The operation at the time of recording information and the operation at the time of tracking in the information recording / reproducing apparatus 200 are the same as those described in the first embodiment.

<3. Third Embodiment> Next, a third embodiment of the present invention will be described. FIG. 5 is a diagram showing an information recording / reproducing device 300 using the solid immersion mirror 1a.

The information recording / reproducing apparatus 300 has substantially the same configuration as the information recording / reproducing apparatus 100 shown in the first embodiment, and the same members are denoted by the same reference numerals. Here, a detailed description of the same members will be omitted.

Information recording / reproducing apparatus 300 of this embodiment
Is the information recording / reproducing apparatus 100 according to the first embodiment.
The difference from the first embodiment is that the light shielding film 33a formed on the lens 32 is set to be larger than the light shielding film 33 in the first embodiment, and the reflection film 13 is formed on the first surface 11 of the solid immersion mirror 1a. That is not done.

Laser light L1 emitted from laser light source 31
Is converted into parallel light by the lens 32, and the light beam cross section is converted into an annular shape (first annular shape) by the light shielding film 33a formed on the first surface side of the lens 32.

When the light from the laser light source 31 is converted into annular light by the lens 32, the ratio of the near-field light component leaching from the solid immersion mirror 1 to the recording medium 8 increases, and the recording medium increases. 8, the recording pits formed on the recording pit 8 can be appropriately detected. For example, when annular light having a numerical aperture NA ≧ 1 is incident on the solid immersion mirror 1a, almost 100% of the information reproducing light L1 becomes the near-field light 9.

The ring-shaped light L1 passes through the polarizing beam splitter 34 and the quarter-wave plate 35, and passes through the solid immersion mirror 1a.
Incident on. Light that has entered the interior of the solid immersion mirror 1a is reflected by a reflective film formed on the second surface (bottom side), and then reflected by the first
The second surface (bottom surface) by total reflection on the surface (top surface side)
Is focused near the center of Then, near-field light 9 of a minute light spot oozes out from the bottom side of the solid immersion mirror 1a. When the near-field light 9 reaches the recording layer 8a of the recording medium 8, information can be reproduced by detecting the reflected light from the recording medium 8.

The light reflected on the recording layer 8a of the recording medium 8 enters the bottom surface of the solid immersion mirror 1a. At this time, a light component L21 traveling in the opposite direction from the solid immersion mirror 1a in the same optical path as the laser light L1 from the laser light source 31 and the solid immersion mirror 1a
And the light component L22 emitted upward from the central portion on the upper surface side of the light emitting device L2.

After passing through the quarter-wave plate 35, the detection light L2 is reflected by the polarization beam splitter 34.

As in the first embodiment, the polarization beam splitter 34 is provided with a light shielding member 38 for shielding the central portion of the detection light L2, and the light is reflected by the polarization beam splitter 34 by the light shielding member 38. Detection light L2
Among them, the light L22 in the central portion is blocked, and the light detector 37
Is only the second annular light L21 corresponding to the outer edge portion of the detection light L2. This light L21
The second annular shape forming the light beam cross section of the laser beam L1
Are formed so as to be substantially the same as the first annular zone shape shown by the light beam cross section of FIG. The second orbicular light L21 is condensed by the condensing lens 36, detected by the photodetector 37, and generates a reproduction signal.

Information recording / reproducing apparatus 300 of this embodiment
Is also configured so that only the light L21 in the annular zone is condensed on the photodetector 37, as compared with the case where the light L22 in the area inside the annular zone is also collected. The main lobe component of the light at the light position becomes sharper. Therefore, the photodetector 37 can detect a reproduction signal with high resolution from the detection light L2. That is, of the light L2 reflected by the polarization beam splitter 34, the light component L22 in the central portion thereof is shielded by the light blocking member 38, and the light component traveling toward the photodetector 37 is detected by the second ring of the detection light L2. By detecting only the band light L21,
The reflected light modulated by the information recorded on the recording medium 8 can be detected with higher resolution.

Therefore, in the information recording / reproducing apparatus 300 of this embodiment, the near-field light 9 for information reproduction can be appropriately generated, and the information recorded on the recording medium 8 can be detected with high resolution. This makes it possible to improve the stability and reliability of the reproduced information at the time of reproducing the information.

However, in the case of the information recording / reproducing apparatus 300 of this embodiment, the near-field light component is increased, but the light intensity is higher in the information recording / reproducing apparatus 100 of the first embodiment. Therefore, when it is necessary to increase the light intensity detected by the photodetector 37, it is desirable to adopt the configuration of the first embodiment.

<4. Modifications> Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the contents described above.

For example, in the first embodiment, of the detection light L2 from the recording medium 8, the light component L
The laser beam L1 irradiating the recording medium 8 is guided to the solid immersion mirror 1 so as to include a region inside the annular zone at the time of light detection, and the near-field light 9 is generated. It is configured. In the second embodiment, of the detection light L4 from the recording medium 8, a light component L41 in a predetermined annular zone is detected, and the laser light L3 applied to the recording medium 8 is detected by light. The light is guided to the solid immersion lens 2 so as to include only the area inside the annular zone area at the time, and the near-field light 9 is generated. Further, in the third embodiment, of the detection light L2 from the recording medium 8, the light component L21 in a predetermined annular zone is detected, and the laser light L1 applied to the recording medium 8 is detected by light. The light is guided to the solid immersion mirror 1 so as to include only the substantially same area as the annular zone at the time, and the near-field light 9 is generated.

However, the present invention is not limited to the configurations of the above-described embodiments, but is configured to detect annular light at the time of detecting light, and to allow light for information reproduction to enter the optical element. In this case, it is sufficient that the light is incident in such a state that the light includes a ring region substantially the same as the ring region used at the time of detection or a region inside the ring region. With such a configuration, it is possible to improve the stability and reliability of the reproduced information at the time of reproducing the information.

In the first embodiment, the information recording / reproducing apparatus 100 uses the solid immersion mirror 1 as an optical element for guiding annular light for information reproduction to the recording layer of the recording medium. Although described, the solid immersion lens 2 shown in FIG. 4 may be used as an optical element for the configuration of the information recording / reproducing apparatus 100 according to the first embodiment (see FIG. 1). However, when the solid immersion lens 2 is used, a condensing lens 44 for giving a condensing action so as to form a minute spot inside the solid immersion lens 2 is required.

Conversely, the configuration of the information recording / reproducing apparatus 200 in the second embodiment (see FIG. 3) is different from the solid immersion mirror 1 shown in FIG. 2 or the solid immersion mirror of the third embodiment. The immersion mirror 1a may be used. In this case, since the solid immersion mirrors 1 and 1a have a self-focusing function, the focusing lens 44 becomes unnecessary.

In the above description, an example has been described in which the operation of reproducing information or recording information on a recording medium is performed using near-field light. However, the present invention is not limited to this. Instead, information may be reproduced or reproduced using far-field light.
Further, the optical element is not limited to the solid immersion mirrors 1 and 1a and the solid immersion lens 2 described above, and other optical elements may be used.

Further, the information recording / reproducing device 100,
Each of the devices 200 and 300 may be a device exclusively for reproducing information (information reproducing device) for reproducing only information.

[0098]

As described above, according to the first aspect of the present invention, the annular light generating means disposed in the optical path of the reflected light from the recording medium between the optical element and the detecting means is provided. By converting the light flux of the reflected light into an annular shape, the reflected light is formed into an annular shape light, and the detecting means is configured to detect the annular shape light. Information can be reproduced, and stability and reliability of the reproduced information can be improved.

According to the second aspect of the present invention, since the irradiation light is configured to enter the optical element as a light flux including the inner area of the annular shape of the reflected light, the light irradiated on the recording medium is formed. Therefore, the intensity of the reflected light from the recording medium also increases, and the stability and reliability of the reproduced information can be improved.

According to the third aspect of the present invention, since the luminous flux of the illuminating light is composed of the annular area of the reflected light and the inner area of the annular area, the luminous flux of the light illuminating the recording medium is reduced. Since the intensity can be increased, the intensity of the reflected light from the recording medium is also increased, and the stability and reliability of the reproduced information can be improved.

According to the fourth aspect of the present invention, since the luminous flux of the illuminating light is constituted by the inner region of the annular shape of the reflected light, the intensity of the light illuminating the recording medium is increased. In addition, the stability and reliability of reproduced information can be improved.

According to the fifth aspect of the present invention, the irradiation light is configured as a light flux composed of a ring-shaped area of the reflected light and input to the optical element. , The information can be reproduced, and the stability and reliability of the reproduced information can be improved.

According to the invention described in claim 6, since the optical element is a solid immersion lens or a solid immersion mirror, local near-field light can be leached from the optical element.

[Brief description of the drawings]

FIG. 1 is a diagram showing an information recording / reproducing device using a solid immersion mirror.

FIG. 2 is a diagram illustrating an example of a solid immersion mirror.

FIG. 3 is a diagram showing an information recording / reproducing apparatus using a solid immersion lens.

FIG. 4 is a diagram illustrating an example of a solid immersion lens.

FIG. 5 is a diagram showing an information recording / reproducing apparatus using a solid immersion mirror, which is different from FIG.

[Explanation of symbols]

 Reference Signs List 1, 1a solid immersion mirror (optical element) 2 solid immersion lens (optical element) 8 recording medium 9 near-field light 31, 41 laser light source 38 light-shielding member (ring light generation means) 37, 47 photodetector (detection means) 43 ring-shaped mirror (ring light generating means) 100, 200, 300 information recording / reproducing device

Continued on the front page (72) Inventor Seiji Kojima 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka F-term in Osaka International Building Minolta Co., Ltd. 2H042 AA15 AA31 2H087 KA13 TA01 TA04 5D119 AA12 DA05 EC37 JA44 JA48 JA64

Claims (6)

[Claims] 1. An information recording / reproducing apparatus which irradiates a recording medium with light for information reproduction and reproduces information by receiving reflected light from the recording medium, wherein the irradiation for information reproduction is performed. A light source that generates light, an optical element that is disposed to face the recording medium, irradiates the recording medium by inputting the irradiation light, and inputs reflected light from the recording medium; and Detecting means for detecting the incident reflected light to reproduce information recorded on the recording medium; and a light flux of the reflected light which is arranged in an optical path of the reflected light between the optical element and the detecting means. By converting the reflected light into annular light by converting the reflected light into annular light,
An information recording / reproducing apparatus comprising: 2. The information recording / reproducing apparatus according to claim 1, wherein the irradiation light is configured to be a light flux including a region inside the annular shape and input to the optical element. Information recording and playback device. 3. The information recording / reproducing apparatus according to claim 2, wherein the luminous flux of the irradiation light is configured to include the ring-shaped region and the ring-shaped inner region. Recording and playback device. 4. The information recording / reproducing apparatus according to claim 2, wherein the luminous flux of the irradiating light is constituted by a region inside the annular zone. 5. The information recording / reproducing apparatus according to claim 1, wherein the irradiation light is configured to be converted into a light flux composed of the annular zone and input to the optical element. Playback device. 6. The information recording / reproducing apparatus according to claim 1, wherein the optical element is a solid immersion lens or a solid immersion mirror.