JP2000155975A - Optical head, optical disk device, and method for manufacturing optical head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical head that is compact, is capable of high-density recording, and can prevent color aberration from occurring, an optical disk device, and a method for manufacturing the optical head. SOLUTION: A laser beam 3a that is emitted from a semiconductor laser 2 is shaped into a parallel beam 3b by a collimator lens 4, is condensed as a condensation beam by a condensing lens 4', and is applied vertically to an incident surface 6a of a transparent medium 6 for condensation. A condensing beam entering from an incident surface 6a is condensed at a first focus FA, is reflected toward a reflection surface 6b by a glare protection reflection film 7B, and is reflected by a reflection film 7A and is condensed at a second focus Fb on a spot formation surface 6c, thus forming a light spot 9a. Light being condensed at the light spot 9a passes through the slit 7a from a spot formation surface 6c and exudes to the outside of the transparent medium 6 for condensation as a near-field beam 9b. The near-field light 9b is applied to a recording layer 8a of an optical disk 8 for recording and reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head, an optical disk apparatus, and a method of manufacturing an optical head using near-field light, and more particularly, to a small-sized optical disk, a high recording density, and prevention of chromatic aberration. The present invention relates to an optical head, an optical disk device, and a method for manufacturing an optical head.

[0002]

2. Description of the Related Art In an optical disk device, the density of an optical disk has been increased from a compact disk (CD) to a digital video disk (DVD). With the increase in capacity, an increase in capacity is increasingly required.

[0003] The recording density of an optical disk is basically controlled by the diameter of a light spot formed on a recording medium. In recent years, a technique of near-field light of a microscope has been applied to optical recording as a technique for reducing the diameter of a light spot. As a conventional optical disk device using this near-field light, for example, a document (Jpn. J. Appl. Phys., Vo1.35)
(1996) P.A. 443), U.S. Pat.
7359, and the document "Technical Digest of Data Sto"
rage, ('98) P. 137 ".

FIGS. 17 (a) and 17 (b) show references (Jpn.
Appl. Phys. , VOL. 35 (1996) p.
443) shows an optical disk device. As shown in FIG. 17A, the optical disc apparatus 190 includes a semiconductor laser 191 for emitting a laser beam 191a and a laser beam 191a from the semiconductor laser 191 for a parallel beam 191a.
b, a coupling lens 192 shaped to b
has an optical fiber 193 polished in a tapered shape so as to become thinner from the output end 193a toward the output end 193b, and transmits the parallel beam 191b from the coupling lens 192 to the input end 193a.
And a recording medium 195 recorded by near-field light 191c leaking from the emission end 193b of the optical fiber 193.

[0005] The recording medium 195 is a phase change medium of GeSb.
It has a recording layer 195a made of Te and has a near-field light 191c.
Is heated by the incident light, causing a phase change between crystal and amorphous, and is recorded using the change in reflectance between the two.

The optical fiber 193 has an input end 193a having a diameter of 10 μm and an output end 193b having a diameter of 50 nm, and is coated with a metal film 194b such as aluminum through a clad 194a. Prevents leaks. Since the diameter of the near-field light 191c is substantially equal to the diameter of the emission end 193b, a high recording density of 10 GB / inch ² is possible.

For reproduction, as shown in FIG. 17 (b), near-field light 191c having a low power that does not cause a phase change is irradiated onto the recording layer 195a by using the same optical head as used for recording. The reflected light 191d therefrom is collected by a condenser lens 196.
The light is focused on a photomultiplier tube (hereinafter abbreviated as “photomultiplier”) 197 and detected.

[0008] FIG.
59 shows an optical head of an optical disk device described in No. 59. The optical head 50 includes an objective lens 5 that collects the parallel light 51.
2 and a bottomed spherical SIL arranged such that the bottom surface 54a is orthogonal to the convergent light 53 from the objective lens 52.
(Solid Immersion Lens) 54. Parallel light 51
Is converged by the objective lens 52, and the condensed light 53 is incident on the spherical incident surface 54b. The convergent light 53 is refracted by the incident surface 54b and is condensed on the bottom surface 54a.
A light spot 55 is formed on the substrate. Inside the SIL 54,
Since the wavelength of light becomes shorter in inverse proportion to the refractive index of the SIL 54, the light spot 55 also becomes smaller in proportion thereto. Most of the light condensed on the light spot 55 is totally reflected toward the incident surface 54b, but part of the light leaks out of the light spot 55 to the outside of the SIL 54 as near-field light 57. The SIL 54 is located at a distance sufficiently smaller than the wavelength of light from the bottom surface 54a.
When the recording medium 56 having the same refractive index as that of
The near-field light 57 couples with the recording medium 56 and the recording medium 5
6 becomes the propagating light. Information is recorded on the recording medium 56 by the propagating light.

The SIL 54 is configured such that the parallel light 51 is focused at a position r / n (r is the radius of the SIL) from the center 54c of the hemispherical surface 54b (this is referred to as Super).
Called the SIL structure. ), The spherical aberration due to the SIL 54 is small, the numerical aperture inside the SIL 54 can be increased, and the light spot 55 can be further miniaturized. That is, the light spot 55 is miniaturized as in the following equation. D _1/2 = kλ / (n · NAi) = kλ / (n ² · NA
o) Here, k: proportional constant depending on the intensity distribution of the light beam (usually about 0.5) λ: wavelength of the light beam n: refractive index of SIL 54 NAi: numerical aperture inside SIL 54 NAo: incidence on SIL 54 Numerical aperture of light Light spot 5 without parallel light 51 being absorbed on the optical path
Since the light is condensed as 5, a high light use efficiency is obtained.
As a result, a light source having a relatively low output can be used, and the reflected light can be detected without using a photomultiplier.

FIG. 20 shows a document “Technical Digest of Data Stora” as a means for condensing light mainly using a reflection condensing surface.
ge, ('98) P. 137 ". This optical head has a parallel laser beam 2b.
Incident surface 101a, concave surface 101a on which
Light-collecting surface 101b, light-collecting surface 1 provided at a position facing
01b, and an aspherical reflecting surface 1 formed around the entrance surface 101a.
01d, a transparent condensing medium 101, a planar reflective film 102 formed on the surface of the planar reflective surface 101c, and an aspherical reflective film 103 formed on the surface of the aspherical reflective surface 101d. . In the optical head configured as described above, the parallel laser beam 2b
Is incident on the incident surface 101a, the parallel laser beam 2b incident on the incident surface 101a is diffused on the incident surface 101a, and the diffused light 2d is reflected on the planar reflector 102,
The reflected light 2e is further reflected by the aspherical reflective film 103 and condensed on the light-collecting surface 101b, and a light spot 9a is formed on the light-collecting surface 101b. The near-field light 9b oozing from the light-collecting surface 101b enables recording and reading on the recording layer 8a of the optical disk 8. This transparent light-collecting medium 10
The numerical aperture NA of the flat reflecting surface 101c is about 0.8, the refractive index of the transparent condensing medium 101 is 1.83,
The NA inside the transparent condensing medium 101 can be about 1.5.

[0011]

However, according to the conventional optical disk device 190, a minute light spot of about several tens of nm can be formed on the recording medium. However, since the optical fiber 193 is tapered, the optical fiber 193 is formed. A part of the laser incident on the surface is absorbed inside, and the light utilization efficiency is 1/1000.
There is a problem that it becomes lower as follows. Therefore, the reflected light 1
I have to use Photomaru 197 to detect 91d,
The optical head is large and expensive. In addition, Photomaru 19
7 has a slow response speed and a heavy optical head, so that high-speed tracking cannot be performed. Therefore, the optical disc cannot be rotated at a high speed, so that there are many problems such as a low transfer rate, and many improvements are required for practical use.

FIG. 19 shows the conventional optical head 5 shown in FIG.
0 is a diagram to explain the problem, Suzuki is Asia-
Pacific Data Storage Conf
OC of erence (Taiwan, '97 .7.)
-1 and shows the relationship between the refractive index n of the SIL 54 and NAo. N of light incident on SIL 54
A, that is, the maximum value θmax of the incident angle θ and the refractive index n of the SIL 54 have a reciprocal relationship, and both cannot be increased independently. As can be seen from the figure, as the refractive index n of the SIL 54 increases, the maximum value NAomax of the incident light NAo gradually decreases. This is the maximum value N
This is because when the NAo increases more than Aomax and the incident angle further increases, the light directly enters the recording medium 56 without passing through the SIL 54, so that the light spot 55 at the position of the recording medium 56 spreads. For example, when the refractive index n = 2, NAomax is 0.44, and the product n · NAomax of both is 0.8 to 0.9 in any combination of both. This is a theoretical limit, and actually becomes a smaller value (0.7 to 0.8).

The light-collecting experiment using the Super SIL is described in B.S. D. Terris et al., Appl. Phys
s. Lett. , Vo 1.68, ('96), P.E. 14
1. In the report. According to this report, a SuperSIL having a refractive index n = 1.83 is placed between an objective lens and a recording medium, and a laser beam having a wavelength of 0.83 μm is condensed to obtain a light spot diameter of 0.317 μm.
That is, light collection equivalent to D _1/2 = λ / 2.3 is achieved. In this case, NA is 0.4 and n · NAmax is 0.2.
It is about 73. Also, the possibility of a recording density of 0.38 × Gbits / cm ² , which is several times the conventional value, is verified using this system.

That is, according to the conventional optical head 50,
Although the light use efficiency is high, the refractive index n of SIL and the maximum NAom
ax has a reciprocal relationship, so the product n · NAoma of both
The theoretical limit for x is 0.8-0.9, and in practice 0.7
０．８0.8, and even when a laser beam having a wavelength of 400 nm is used, the light spot can be narrowed down to only about 0.2 μm in diameter at most. However, there is a problem that the recording density cannot be increased.

Further, according to the conventional optical head shown in FIG. 20, since the parallel laser beam 2b is incident on the optical disk surface in a vertical direction, the height of the optical head becomes high, and there is a problem that the size of the optical head cannot be reduced. In addition, since the incident light is refracted by the incident surface 101a, chromatic aberration is generated and the focus is shifted as in the second conventional example, so that there is a problem that the automatic focus control is required.

Accordingly, it is an object of the present invention to provide an optical head, an optical disk device, and a method of manufacturing an optical head which are small in size, enable high recording density, and prevent the occurrence of chromatic aberration.

[0017]

According to the present invention, there is provided an optical head for forming a light spot by condensing a laser beam, the laser beam emitting means for emitting the laser beam, and the laser beam. Focusing means for focusing the laser light from the light emitting means, and a first point where the laser light is focused by the focusing means and a second point where the light spot is formed at two focal points. A reflection surface formed of a part of a spheroid and having a reflector formed on the outside, an incidence surface on which the laser light from the laser light emission unit is incident, and a spot formation surface on which the light spot is formed. The laser beam condensed by the light condensing means, reflected or refracted at the first point, and reflected toward the reflection surface by the reflector to reflect the second point on the spot forming surface. Form the light spot on And a light-shielding film having a slit in a predetermined direction at a position blocking the light spot and provided on a surface of the spot forming surface of the transparent light-collecting medium. An optical head is provided.
According to the above configuration, since the reflection surface that is a part of the spheroidal surface can bend the optical axis of the laser beam from the light condensing means almost vertically, the light axis of the light condensing means is spot-formed. Can be arranged substantially in parallel with each other, and the height direction can be reduced. Further, since the half-vertical angle of the laser light reflected by the reflecting surface can be made larger than the half-vertical angle of the laser light focused on the first point by the focusing means, the half-vertical angle is formed on the spot forming surface. It is possible to miniaturize the light spot to be emitted. By shielding the light spot formed on the spot forming surface with a light shielding film having a slit, a near-field light spot smaller than the light spot formed on the spot forming surface can be obtained.

In order to achieve the above object, the present invention has an optical head that forms a light spot by condensing a laser beam,
In an optical disc apparatus that records or reproduces information on a recording track on a rotating optical disc based on the light spot, the optical head includes a laser beam emitting unit that emits the laser beam, and a laser beam emitting unit that emits the laser beam. Focusing means for focusing the laser light, and a spheroid having two focal points at a first point at which the laser light is focused by the focusing means and a second point at which the light spot is formed. A reflecting surface formed of a part of a surface and having a reflector formed outside, an incident surface on which the laser light from the laser light emitting unit is incident, and a spot forming surface on which the light spot is formed; The laser light condensed by the light condensing means and reflected or refracted at the first point and directed toward the reflection surface is reflected by the reflector, and the laser light is reflected at the second point on the spot forming surface. And a transparent condensing medium to form a Tsu door,
An optical disc device, comprising: a light-shielding film provided on a surface of the spot forming surface of the transparent light-collecting medium having a slit in a direction orthogonal to the recording track at a position where the light spot is blocked. I will provide a. According to the above configuration, since the reflection surface that is a part of the spheroidal surface can bend the optical axis of the laser beam from the light condensing means almost vertically, the light axis of the light condensing means is spot-formed. Can be arranged almost in parallel with the optical disk, and the height direction can be reduced, and the optical disk device can be reduced in size. Further, since the half-vertical angle of the laser light reflected by the reflecting surface can be made larger than the half-vertical angle of the laser light focused on the first point by the focusing means, the half-vertical angle is formed on the spot forming surface. It is possible to miniaturize the light spot to be emitted. By shielding the light spot formed on the spot forming surface with a light shielding film having a slit, a near-field light spot smaller than the light spot formed on the spot forming surface can be obtained.

In order to achieve the above object, the present invention provides an optical head that forms a light spot by condensing a laser beam, and a plurality of rotating optical disks coaxially arranged at a predetermined interval. An optical disk device that performs recording or reproduction on a recording track on the plurality of optical disks based on the light spot, wherein the optical head comprises: a laser light emitting unit that emits the laser light; Focusing means for focusing the laser light from the means, and a first point at which the laser light is focused by the focusing means and a second point at which the light spot is formed as two focal points. A reflecting surface formed of a part of a spheroidal surface and having a reflector formed outside; an incident surface on which the laser light from the laser light emitting unit is incident; and a spot forming surface on which the light spot is formed. , It is condensed by the condensing means,
A transparent light-collecting medium that reflects or refracts the laser light toward the reflection surface after being reflected or refracted at the first point, and reflects the laser light at the second point on the spot formation surface by reflecting the laser light; An optical disk comprising: a light-shielding film provided on a surface of the spot forming surface of the transparent light-collecting medium, having a slit in a direction orthogonal to the recording track at a position where the light spot is blocked. Provide equipment.
According to the above configuration, since the reflection surface that is a part of the spheroidal surface can bend the optical axis of the laser beam from the light condensing means almost vertically, the light axis of the light condensing means is spot-formed. Can be arranged almost in parallel with each other, the height direction can be reduced, and the distance between optical disks can be reduced. Also,
The half vertex angle of the laser beam reflected by the reflecting surface can be made larger than the half vertex angle of the laser beam converged on the first point by the condensing means, so that it is formed on the spot forming surface. The light spot can be miniaturized. By shielding the light spot formed on the spot forming surface with a light shielding film having a slit, a near-field light spot smaller than the light spot formed on the spot forming surface can be obtained.

In order to achieve the above object, the present invention has a substantially spheroidal shape having two focal points at a point where laser light is focused and a point where a light spot is formed by the laser light. A transparent light-collecting medium having a spot forming surface on which a light spot is formed is prepared, and the spot-forming surface of the transparent light-collecting medium has a width smaller than the light spot and a length larger than the light spot. Forming a photoresist layer having an outer diameter having a concave portion by removing a region where the photoresist layer is not present on the spot forming surface of the transparent light-collecting medium at a predetermined depth equal to or less than the wavelength of the laser beam. And forming a light shielding film having an opening corresponding to the outer diameter by depositing a light shielding material in the concave portion.
According to the above configuration, it is possible to form a light-shielding film having an opening having a width smaller than the light spot formed on the spot formation surface by photolithography and a length larger than the light spot.

[0021]

1 (a) and 1 (b) show a first embodiment of the present invention.
1 shows an optical head according to an embodiment. This optical head 1
Are a semiconductor laser 2 for emitting a laser beam 3a, a collimator lens 4 for shaping the output light 3a of the semiconductor laser 2 into a parallel beam 3b, a condensing lens 4 'for condensing the parallel beam 3b, and a condensing lens 4 And a substantially semi-spheroidal transparent light-collecting medium 6 into which a light-converged beam 3c is incident.

The transparent light-condensing medium 6 has an incident surface 6a on which the converging beam 3c is incident from the condensing lens 4 ', a reflecting surface 6b formed from a part of the spheroid, and a spheroidal surface. 1
And spot forming surface 6 having second focal points Fa and Fb
c. A reflection film 7A is applied to the surface of the reflection surface 6b of the transparent light-collecting medium 6, and the surface on the spot formation surface 6c has a slit 7a in a direction Y orthogonal to the track direction X on the optical disk 8. A light-shielding reflection film 7B is provided. The entrance surface 6a is formed in a convex spherical shape with the center of curvature coincident with the first focal point Fa.

FIG. 2 shows the detailed shape of the transparent light-collecting medium 6. As shown in the figure, the main axis of the cross section (6b) of the spheroid is taken as the x-axis, the vertical axis is taken as the y-axis, and the direction orthogonal to the x- and y-axes is taken as the z-axis. b, the section (6b) is

(Equation 1) And the coordinates of the bifocals Fa and Fb are

(Equation 2)And the coordinates of the center point P are (a, b), the eccentricity e
Is e = (a^Two-B^Two) / A^Two It is expressed as The incident light 3c, 3c 'is at the first focal point Fa.
The light is reflected as shown by 3d and 3d ', and further 3e and 3e'
The light is converged on the second focal point Fb as shown by. 3d reflected light
When the intersection of the reflecting surfaces 6b is on the right side of the center point P,
The value of the half vertex angle θe of the light 3e is calculated from the half vertex angle θc of the incident light 3c.
growing. Therefore, the NA of the condensed light 3e is
It is possible to increase more. For example, spheroid
The major axis a and minor axis b of the surface are 1.2 mm and 1 mm, respectively.
Then, the NA of the condenser lens 4 'is set to 0.5, as shown in FIG.
Thus, the spherical incident surface 6a centered on the first focal point Fa
Incident vertically, and the angle between the incident light 3c and the x-axis is 70 degrees.
Then, the half vertex angle θc of the incident light 3c is 30 degrees, and
The angle between the x axis and the x axis is -70 degrees, and the angle between the condensed light 3e and the x axis is
It is about 42 degrees. On the other hand, the angle between the incident light 3c 'and the x-axis is
10 degrees and the angle of the condensed light 3e 'with the x-axis is about 20 degrees.
You. Accordingly, the N of the condensed light 3e condensed on the second focal point Fb
A can be increased to about 0.86 as compared with the conventional example. Ma
This value can also be increased by increasing the eccentricity even further.
It is possible to further increase. In addition, by selecting the values of the major axis a and the minor axis b according to the design,
From the origin of the second focal point Fb while maintaining the value of NA.
Can be adjusted appropriately. This is the ellipsoid
This is because there are two degrees of freedom to set. Assuming that NA of the condensed light 3e is NAi, at the second focal point Fb
Diameter D of the light spot 9a_1/2Is given by the following equation. D_1/2= K · λ / (n · NAi) where k is a constant determined by the intensity distribution of the incident light, and Gaussian
For a beam, it is about 0.5. Λ is the wave of the light source
Length, n is the refractive index of the transparent light-collecting medium 6, and
GalnAIP red laser (wavelength 0.63μm), transparent collection
Heavy flint glass (n = 1.83) as the medium 6 for light
When used, the diameter D of the light spot 9a _1/2As about
0.2 μm is obtained. This is the conventional example shown in FIG.
It is almost half of the value obtained in

The light-shielding reflection film 7B is made of titanium (Ti) and has a thickness (for example, 10 nm) smaller than the wavelength of the laser light.
And a slit 7a in a direction Y orthogonal to the track direction X is formed at a position corresponding to the light spot 9a to block light emitted directly from the light spot 9a to the outside. The light 9b is formed.
The width of the slit 7a W, length L, and the diameter of the light spot 9a and D _1/2, W, the relationship between L and D _1/2, W <D _1/2 and,, L> D _{1 / 2} is set. Thereby, near-field light 9b having a length of about D _1/2 and a width W is formed. In the present embodiment, the width W is set to about a fraction of the diameter D of the light spot 9a, that is, about 1/10 of the wavelength of the laser light (for example, 50 nm). Note that the slit width W may be smaller than 50 nm in accordance with the progress of the technology for increasing the recording density of the optical disc and the technology for forming the slit. Further, the light-shielding reflection film 7B may be subjected to a process of absorbing laser light (for example, a black process) around the slit 7a, or may be formed of a material that absorbs laser light. This prevents a decrease in the S / N ratio due to the laser light reflected around the slit 7a of the light-shielding reflection film 7B.

The width W of the slit 7a is 1/1 of the laser wavelength.
Since it is as small as about 0, no propagating light is emitted from the slit 7a, and the near-field light 9b having a size approximately equal to the width W of the slit 7a in the track direction X and several times as large in the vertical direction as the wavelength. It exudes to a similar close distance. By disposing a medium having a refractive index similar to that of the transparent light-condensing medium 6, for example, the recording medium 8, in proximity to the near-field light 9 b, the near-field light 9 b is transmitted to the recording layer 8 a of the optical disc 8 by a This light allows recording and reading on the recording layer 8a. The amount of the propagated light is represented by the following equation.

(Equation 3) Here, Io: the total power of the laser ω: the radius of the light spot 9a on the light-collecting surface 6b a: the half width of the slit 7a That is, in the case of a red laser, the light amount of the laser light passing through the slit 7a is the entire light spot 9a. About 20 of power
%, And 30% in the case of blue light, so that the light-collecting efficiency can be improved to 100 times or more that in the case where a conventional optical fiber is used.

FIGS. 3A to 3D show a method of applying the light-shielding reflection film 7B and a method of forming the slit 7a. First, a photoresist film 70 for electron beam exposure is applied to the bottom surface 6d of the transparent converging medium 6 having a substantially semi-spheroidal shape.
Exposure with an electron beam is performed to leave a portion corresponding to a (FIG. 3A), and after development, the bottom surface 6d is anisotropically etched by about 100 A by dry etching to form a spot forming surface 6c (FIG. 3A). 3 (b)). A CF4-based gas is used as an etching gas. Next, a Ti film 71 for a light-shielding film is deposited on the entire surface by sputtering at about 100 A (FIG. 3C), and the Ti film 71 corresponding to the slit 7a is lifted off by dissolving the photoresist film 70. (FIG. 3 (d)). Thus, the light-shielding reflection film 7B having the slit 7a is formed. In addition, the light shielding reflection film 7
B may be a film other than the Ti film as long as it is a film having a light-shielding property and an excellent adhesion to glass. The light-shielding reflection film 7B may be formed with a reflection film that reflects the incident light 3c near the first focal point Fa and a light-shielding film having a slit 7a near the second focal point Fb. In this case, a photoresist film is formed around the portion corresponding to the slit 7a and around the light shielding film, and the reflection film and the light shielding film can be formed by the above-described photolithography method.

Next, the operation of the optical head 1 will be described. When a laser beam 3a is emitted from the semiconductor laser 2, the laser beam 3 is shaped into a parallel beam 3b by a collimator lens 4 and is focused by a focusing lens 4 '.
The light is condensed as b ′, and is perpendicularly incident on the incident surface 6a of the transparent light condensing medium 6. In this way, the condensed beam 3b ′ incident from the incident surface 6a is once condensed on the first focal point Fa, then reflected by the light-shielding reflection film 7B toward the reflection surface 6b, and further reflected on the reflection surface 6b. The light is reflected by the reflection film 7A and condensed at the second focal point Fb on the spot forming surface 6c to form a light spot 9a on the spot forming surface 6c. The light focused on the light spot 9a oozes out of the transparent light-gathering medium 6 as near-field light 9b from the spot forming surface 6c through the slit 7a on the light-shielding reflection film 7B. By the near-field light 9b, the recording layer 8 of the optical disk 8 is
Recording / reproduction is performed by irradiating a. The spot forming surface 6c is also used as a slider surface for levitating and traveling on the optical disk 8. The flying height varies from several tens to 200 nm, depending on the wavelength of the light and the spot diameter.

According to the optical head 1 having the above configuration, the following effects can be obtained.
Is obtained. (A) Forming the reflection surface 6b in a spheroidal shape
In this way, the optical axis of the incident light is almost parallel to the disk.
To the vertical direction, and in the transparent light-collecting medium 6.
NA on the spot forming surface 6c
Can be formed. For example, the spheroid
When the major axis a and the minor axis b are 1.2 mm and 1 mm, respectively.
The NA of the focused beam is 0.86,
Larger NA compared to an optical head using a condensing system such as L
it can. Further, by further increasing the eccentricity e, the NA
Can be further increased. Also, high NA
As a result, the light spot 9a can be miniaturized.
You. (B) Chromatic aberration does not occur because of the reflection type light collecting system. (C) The optical axis can be bent almost vertically by the reflecting surface 6b.
Optical element is almost horizontal to the disk surface.
And the height of the optical head can be reduced.
Wear. This makes it possible to use multiple optical discs,
When used, the capacity can be increased. Also light
Since the entire disk unit can be made thinner,
When used as a wall, it can be reduced in size and is effective. (D) Near-field light oozing from the miniaturized light spot 9a
Are orthogonal to the track direction X formed on the light-shielding reflection film 7B.
Since it is narrowed by the slit 7a in the direction Y, the conventional
Near-field light compared to the case using Super SIL
9b can be reduced to a fraction of the width in the track direction X.
To increase the recording density in the track direction X several times
Can be. (E) In the direction Y orthogonal to the track direction X of the near-field light 9b
Length is spot diameter D _1/2Determined by spot diameter
D_1/2Reduced track pitch
Can be done. (F) Width of the near-field light 9b smaller than the wavelength of the laser beam 3
Of the light propagating from the slit 7a
Since the light intensity at the center does not change, high light use efficiency is obtained.
Can be Therefore, a relatively low power semiconductor of several milliwatts
Laser 2 can be used as a light source. Also, the optical disk 8
The reflected light from the light also increases in proportion to the propagating light from the slit 7a.
To detect the reproduction light, the conventional optical disk memory
The photodetector used can be used.
The optical head 1 can be reduced in size and weight.
In addition, high-speed reading can be performed. (G) The width of the near-field light 9b in the track direction X is the slit width W.
And the spot diameter D on the spot forming surface 6c._1/2
, Collimator lens 4, condenser lens
The effect of spot diameter fluctuation due to 4 'aberration and temperature change
Providing a highly reliable optical head that is difficult to receive

FIGS. 4A and 4B show modified examples of the light-shielding reflection film 7B. As shown in FIG. 4A, the light-shielding reflection film 7B
At the time of etching the bottom surface of the transparent light-collecting medium 6, the surface to be etched is inclined with respect to the incident light by an operation such as inclining an area 6c ′ near the slit 7a of the spot forming surface 6c,
The shape may be a convex or concave conical surface. FIG.
As shown in (b), when etching the bottom surface of the transparent light-collecting medium 6, fine irregularities may be formed on the etched surface by an operation such as etching at a relatively large current and at a high speed. When the reflectance of the region 6c 'near the slit 7a of the light-shielding reflection film 7B is high, the light intensity reflected by the light-shielding reflection film 7B becomes stronger than the signal light returning from the slit 7a, and amplification of the pre-amplification at the time of signal processing is performed. Since the ratio cannot be made large, the S / N is reduced. On the other hand, if the absorptance in the light shielding reflection film 7B is high,
The temperature of the portion of the light-shielding reflection film 7B irradiated with the light spot 9a rises, and this heat undesirably affects recording. Therefore, by adopting a structure as shown in FIGS. 4A and 4B, the reflected light 3f does not return to the condenser lens 4 ', and the S / N can be improved. On the other hand, the reflected light passing through the slit 7a follows the same path as the incident light 3e and enters a photodetector (not shown). As a result, the ratio of stray light entering the photodetector can be reduced, so that the gain of the DC preamplifier can be increased and the S / N can be improved.

FIG. 5 shows an optical head according to a second embodiment of the present invention. This optical head 1 is the same as the first embodiment except that a prism 5 is arranged between a collimator lens 4 and a condenser lens 4 'in the first embodiment. ing. Thus prism 5
Is used, the semiconductor laser 2 and the collimator lens 4 can be arranged in parallel to the disk surface, and the entire optical head 1 can be made thinner. The height of the transparent condensing medium 6 is about 1 mm, and the prism 5
The height to the top can be about 2 mm,
The height is almost the same as that of a magnetic head for a magnetic hard disk. It is also possible to replace the prism 5 and the condensing lens 4 'with one hologram, thereby reducing the number of components and making the optical head smaller and thinner.

FIG. 6 shows an optical head according to a third embodiment of the present invention. The optical head 1 has the same configuration as that of the second embodiment except that the incident surface 6a of the transparent light-collecting medium 6 has a concave spherical surface in the second embodiment. The center of this concave spherical entrance surface 6a is located at the first focal point F
a, and the first focal point Fa is located inside the spheroid constituting the reflection surface 6b. With such an arrangement, the light condensed at the first focal point Fa by the condensing lens 4 'is reflected by the reflection film 7B and enters the incident surface 6a. In this case, since the light is perpendicularly incident on the incident surface 6a,
As in the first embodiment, the light reaches the reflecting surface 6b without being refracted, and is condensed at the second focal point Fb. In this case, the diameter of the light spot 9a can be reduced to the same extent as in the first embodiment.

FIGS. 7A and 7B show an optical head according to a fourth embodiment of the present invention. In the optical head 1 according to the first embodiment, the incident surface 6a is made substantially perpendicular to the disk surface, the major axis L of the spheroid is inclined with respect to the spot forming surface 6c, and the first surface is formed on the incident surface 6a. Is formed, the second focal point Fb is formed on the spot forming surface 6c, and the reflection layer 7B is omitted. The other configuration is the same as that of the first embodiment. With this configuration, the incident light 3c can be made incident parallel to the disk surface, and the semiconductor laser 2 and other optical systems 4, 4 'can be arranged parallel to the disk surface. Further, the thickness of the optical head can be reduced, and the assembly of the optical head can be simplified. In the first and third embodiments, the first focal point Fa can be separated from the spot forming surface 6c by inclining the major axis L of the spheroid with respect to the spot forming surface 6c. Can be easily designed, and other optical systems can be arranged in parallel to the disk surface in the same manner as in the present embodiment, so that similar effects can be expected.

FIG. 8A shows an optical disk apparatus according to the first embodiment of the present invention, and FIG.
It is -A sectional drawing. In the optical disc device 100, a recording layer 121 made of a GeSbTe phase change material is formed on one surface of a disc-shaped plastic plate 120, and an optical disc 12 that is rotated by a motor (not shown) via a rotating shaft 11; Optical recording /
An optical head 1 for performing optical reproduction, a linear motor 14 for moving the optical head 1 in the tracking direction 13, and a suspension 15 for supporting the optical head 1 from the linear motor 14 side
And an optical head drive system 16 for driving the optical head 1, and a signal processing system 17 for processing a signal obtained from the optical head 1 and controlling the optical head drive system 16. The linear motor 14 includes a pair of fixed portions 14A, 14A provided along the tracking direction 13 and a pair of fixed portions 14A.
A, and a movable coil 14B that moves on 14A.
The optical head 1 is supported by the suspension 15 from the movable coil 14B.

FIG. 9 shows details of the optical disc 12. The optical disc 12 has a high recording density corresponding to the miniaturization of the light spot 9a formed by the optical head 1. As the plastic plate 120, for example, a polycarbonate substrate or the like is used, and a groove portion 12a is formed on one surface thereof. The optical disc 12 has an Al reflective film layer (100 nm thick) 122, an SiO ₂ layer (100 nm thick) 123, and a GeSbTe recording layer (15 n) on the surface of the plastic plate 120 on which the groove 12 a is formed.
m) 121 and a SiN protective layer (50 nm thick) 124 are laminated. In the present embodiment, the land portion 12b
Information is recorded on the track, and the track pitch is 0.25μ.
m, and the depth of the groove portion 12a is about 0.1 μm. The mark length is 0.13 μm and the recording density is 19 Gbit
s / inch ² and 27GB for 12cm disc
, And the recording density could be increased to 7.6 times that of the related art.

FIGS. 10A and 10B show the optical head 1 of the optical disk apparatus 100 according to the first embodiment. FIG. 10A is a side view and FIG. 10B is a plan view. The optical head 1 has a flying slider 18 that floats on the optical disk 12. On the flying slider 18, an edge-emitting semiconductor laser 2 made of, for example, AlGalnP and emitting a laser beam 3 a having a wavelength of 630 nm, and a semiconductor. A collimator lens 4 for shaping a laser beam 3a emitted from a laser 2 into a parallel beam 3b;
8, a holder 20 made of a fused quartz plate, and a holder 3 for supporting the semiconductor laser 2 via a piezoelectric element 41.
7C, a polarizing beam splitter 22 for separating the parallel beam 3b from the semiconductor laser 2 and the reflected light from the optical disk 12, and a quarter-wave plate 23 for converting the linearly polarized light of the parallel beam 3b from the semiconductor laser 2 to circularly polarized light. And a condenser lens 4 ′ for condensing the parallel beam 3 b from the １ ／ wavelength plate 23.
In addition, a transparent condensing medium 6 and a photodetector 24 mounted on the flying slider 18 and inputting the reflected light from the optical disk 12 via the beam splitter 22 are arranged. Also, the whole is stored in the head case 25,
The head case 25 is fixed to a tip of the suspension 15.

The transparent light-collecting medium 6 has, for example, a refractive index n =
Made of heavy flint glass with 1.91, height 1m
m, 2 mm in length. This transparent light-collecting medium 6 has an incident surface 6a and a reflecting surface 6b, as in the case of the transparent light-collecting medium 6 shown in FIG. The flying slider 18 is made of a transparent medium so that the surface 18a of the flying slider 18 corresponds to the spot forming surface 6c, and the light spot 9a is formed on the spot forming surface 18a of the flying slider 18. A light-shielding film 7 having a slit 7a is formed on the spot forming surface 18a of the flying slider 18 in the same manner as shown in FIG. The slit 7a is, as shown in FIG.
It is formed such that the longitudinal direction is a direction Y orthogonal to the track direction X.

As shown in FIG. 10 (b), the flying slider 18 has a light spot 9 formed on the spot forming surface 18a.
The groove 18b is formed so as to generate a negative pressure in a portion other than the peripheral portion of the portion a. The gap between the flying slider 18 and the optical disk 12 is kept constant as the flying height by the action of the negative pressure by the groove 18b and the spring force of the suspension 15. In the present embodiment, the flying height is about 0.06 μm.

The optical head drive system 16 modulates the output light of the semiconductor laser 2 with a recording signal at the time of recording, thereby causing a phase change between crystalline and amorphous in the recording layer 121, and as a difference in reflectance between the phases. At the time of recording and reproduction, the output light of the semiconductor laser 2 is continuously irradiated without being modulated, and the difference in reflectance at the recording layer 121 is detected by the photodetector 24 as a change in reflected light. Has become.

The signal processing system 17 generates an error signal and a data signal for tracking control based on the reflected light from the optical disk 12 detected by the photodetector 24, and converts the error signal into a high frequency band by a high-pass filter and a low-pass filter. An error signal and an error signal in a low frequency range are formed, and tracking control is performed on the optical head drive system 16 based on these error signals. Here, an error signal for tracking is generated by a sample servo method (optical disc technology, Radio Technology Co., p. 95).
bleed Track) is intermittently provided on the track,
In this method, an error signal is generated from the fluctuation of the reflection intensity. In the case of the sample servo method, since the recording signal and the tracking error signal are separated in a time-division manner, the two are separated by a gate circuit in a reproducing circuit.
The error signal may be generated by a push-pull method using interference with light reflected from the groove 12a.

FIG. 11 shows the piezoelectric element 41. The piezoelectric element 41 includes a plurality of electrode films 411 connected to the pair of electrode terminals 410, 410, and a multilayer PZT thin film (about 20 μm thick) 412 formed between the electrode films 411. The piezoelectric element 41 is attached to the holder 37C, supports the light-collecting transparent medium 6 with the piezoelectric element 41, and scans in a direction Y (tracking direction) orthogonal to the track direction X.

Next, the operation of the optical disk device 100 according to the first embodiment will be described. The optical disk 12
The flying slider 18 is rotated at a predetermined rotation speed by a motor (not shown), and floats on the optical disk 12 by the action of the negative pressure generated by the rotation of the optical disk 12 and the spring force of the suspension 15. Optical head drive system 1
When the laser beam 3a is emitted from the semiconductor laser 2 by the drive by the laser 6, the output light 3a of the semiconductor laser 2 becomes
After being shaped into a parallel light beam 3 b by the collimator lens 4, the polarization beam splitter 22 and the 板 wavelength plate 2
3, the light enters the first focal point Fa of the incident surface 6a of the transparent light-collecting medium 6. The parallel light beam 3b is output from the 波長 wavelength plate 2
3, the light is changed from linearly polarized light to circularly polarized light by the ４ wavelength plate 23. Circularly polarized parallel light beam 3b incident on the first focal point Fa of the entrance surface 6a of the transparent light-collecting medium 6
Is refracted and reaches the reflecting surface 6b, is reflected by the reflecting layer 7A formed on the reflecting surface 6b, and is condensed at the second focal point Fb of the spot forming surface 18a of the flying slider 18. A minute light spot 9a is formed on the spot forming surface 18a of the flying slider 18. Slit 7 under this light spot 9a
A part of the light of the light spot 9a leaks out of the lower surface of the flying slider 18 as the near-field light 9b from the a, and the near-field light 9b propagates to the recording layer 121 of the optical disk 12 to perform optical recording or optical reproduction. Will be The reflected light reflected by the optical disk 12 reverses the path of the incident light, is reflected by the reflecting layer 7A formed on the reflecting surface 6b of the transparent light-collecting medium 6, and is reflected by the polarizing beam splitter 22 in the 90-degree direction. The light is reflected and enters the photodetector 24. The signal processing system 17 includes the photodetector 2
An error signal and a data signal for tracking control are generated based on the reflected light from the optical disk 12 incident on the optical disk 4, and tracking control is performed on the optical head drive system 16 based on the error signal.

According to the optical disc apparatus 100 of the first embodiment, the N
A is 0.86, and as a result, a very small light spot 9b having a spot diameter D _{1/2 of} about 0.2 μm is obtained.
0% is passed through a slit 7a having a width of 50 nm to emit near-field light 9b.
As a result, the light can be incident on the recording layer 121 of the optical disk 12, and the ultra-high-density (60 Gbits / inch ² ) ultra-high-density optical recording / reproduction becomes possible. In addition, since recording and reproduction can be performed without performing the automatic focus control, an automatic focus control mechanism is not required, so that the weight of the optical head 1 can be significantly reduced and the size of the optical head 1 can be reduced. That is, the size of the optical head 1 was 6 mm in height, 4 mm in width, 8 mm in length, and 0.6 g in weight. Therefore, the moving coil 1 of the linear motor 14
4B and the weight of the movable part including the suspension 15
0 g or less. As a result, a bandwidth of 50 kHz or more and a gain of 60 or more were obtained using only the linear motor 14. Therefore, tracking was possible under rotation of 600 rpm, and an average transfer rate of 60 Mbps was obtained. Also, by adopting the sample servo method, the recording signal and the tracking error signal are separated in a time-division manner.
The photodetector 24 does not need to be a split type, and for example, a 1 mm square PIN photodiode can be used. Since the photodetector 24 does not need to be a split type, the detection system can be significantly simplified and lightened. Further, since the weight of the transparent light-collecting medium 6 is as light as 5 mg or less, the resonance frequency of the system supporting the transparent light-collecting medium 6 can be made 300 kHz or more, and 0 V at a voltage of 5 V applied between the electrode terminals 410 and 410. A displacement of 0.5 μm or more was obtained. In addition, the two-stage control by the piezoelectric element 41 and the linear motor 14 allows 80 d
A band of 300 kHz was obtained with a gain of B, and tracking could be performed with an accuracy of 5 nm under high-speed rotation (3600 rpm). As a result, in the present embodiment, the transfer rate can be increased to six times that of the optical disk device 100 without using the piezoelectric element 41, that is, 360 Mbps. Further, when a multi-beam optical head described later is used, it is further increased by 8 times to 500 Mb.
Transfer rates near ps were obtained. Also, an average seek speed of 10 ms or less was achieved for a 12 cm disk. As a result, the access time at 3,600 rpm becomes 20 ms or less.

In the above embodiment, the sample servo method was used to generate the error signal for tracking control. However, the recording track was made to meander around, and the modulation of the reflected light was changed to the meandering frequency. A wobbled track method of detecting in synchronization and generating an error signal may be used. Also, for tracking of a read-only disc, CD
It is also possible to use a three-spot method as performed in the above. That is, a diffraction grating is inserted between the collimator lens 5 and the polarizing beam splitter 22, and ±
An error signal can be generated by arranging photodetectors for detecting the reflected light of the primary light from the disc on both sides of the main beam detecting element and calculating the difference between the outputs. It is also possible to perform a push-pull control that detects an imbalance between the left and right of the diffracted light from the side of the recording track and generates an error signal. In this case, the diffracted light is incident on a two-division type photodetector, and a differential output error signal is generated. Further, the optical head 1 of the present embodiment can be used as it is for recording and reproducing on a write-once optical disc (disc having uneven bits formed by light absorption of a dye). Further, by mounting a thin film coil around the light spot 9a formed on the spot forming surface 18a of the flying slider 18 and performing magnetic field modulation, magneto-optical recording using a magneto-optical medium becomes possible. However, in the case of reproduction, in order to generate a signal by detecting the rotation of the plane of polarization of light by polarization analysis, the polarization beam splitter 22 is changed to a non-polarization splitter, and an analyzer is arranged in front of the photodetector. There is a need. In this embodiment, an edge-emitting laser is used as a laser source.
CSEL) can also be used. In the case of a surface emitting laser, the maximum output in the fundamental mode (TEM00) is 2 m
Although it is about W and 1/10 or less of the edge emitting laser, in the present embodiment, the light density is reduced to one digit because the diameter is reduced to a fraction of the light spot diameter used in the conventional optical disk device. Since the height can be increased as described above, recording can be performed even with a surface emitting semiconductor laser. In the case of a surface-emitting type semiconductor laser, wavelength fluctuation due to temperature is small, and chromatic aberration correction can be unnecessary. In this embodiment, the piezoelectric element is used for driving the light spot. However, the present invention is not limited to this, and a light spot driving type semiconductor laser as shown in FIG. 15 described later may be used.

FIG. 12 shows an optical disk device according to a second embodiment of the present invention. In the first embodiment, the linear motor 14 is used for the seek operation. In the second embodiment, the rotary linear motor 43 used for the hard disk is used. The optical head 1 is connected to a rotary linear motor 43 by a suspension 33 rotatably supported by a rotary shaft 33a. With such a configuration, the rotary linear motor 43 can be arranged outside the optical disc 12, so that the optical head 1 can be made thinner and the entire optical disc apparatus 100 can be downsized. In addition, this allows the optical disc 12 to operate at high speed (3
600rpm), 360Mb on average
A data transfer rate of ps or more becomes possible.

FIG. 13 shows an optical disk device according to the third embodiment of the present invention. This optical disk device 100
In the second embodiment shown in FIG. 12, the semiconductor laser 2, the collimator lens 3, the holder 3
7C, the laser beam generation system including the piezoelectric element 41 and the light detection system including the beam splitter 22, the quarter-wave plate 23, and the photodetector 24 are separated and arranged in the fixing unit 200, and fixed to the optical head 1. The unit 200 is optically connected by an optical fiber 201.

According to the optical disk device 100 according to the third embodiment, the distance from the optical fiber 201 to the spot forming surface is as short as about 1 mm.
Since the defocus due to shrinkage is small and the width of the near-field light in the track direction is fixed by the slit width,
Since the influence of the temperature fluctuation is small, the automatic focus control can be omitted. Further, since the laser beam generation system and the light detection system are separated from the optical head 1 according to the second embodiment, the size of the optical head 1 is 1 mm in height, 2 mm in length / width, and the weight is about 10 mg. Was. By using such an ultra-light and thin optical head 1, high-speed tracking by the rotary linear motor 43 becomes possible, and a high transfer rate and a small optical disk device can be provided. Further, this optical disk device can be provided as a stack type similar to the optical disk device of FIG. 14 to be described later to provide a large-capacity optical disk device. In order to perform high-speed tracking, a piezo element (not shown) may be attached to the suspension 33 and the tip of the suspender 33 and the optical head may be driven as conventionally proposed.

FIG. 14 shows an optical disk device according to a fourth embodiment of the present invention. This optical disk device 100
Is an optical head 1 using the transparent light-collecting medium 6 shown in FIG.
Is applied to a five-stacked disk stack type optical disk device, in which five optical disks 12 having recording layers 121, 121 respectively attached to the upper and lower surfaces of a plastic substrate 120, and a recording layer of each optical disk 12 And ten suspensions 33 for supporting the optical head 1 rotatably by a rotating shaft 44.
And a rotary linear motor 45 that drives the suspension 33. The recording layer 121 may be a phase change type medium or a magneto-optical type medium. Rotary linear motor 4
5 is a movable piece 45a to which the suspension 33 is connected.
And electromagnets 45c, 45c connected by a yoke 45b to drive the movable piece 45a. The structure of the optical head 1 is basically the same as that shown in FIG.
Transparent condensing medium 6 having a paraboloid of revolution and AlGalnN
A system laser (630 nm) is used, and the light spot diameter is 0.2 μm. The disc diameter is 12 cm, the track pitch and the mark length are 0.07 μm and 0.05, respectively.
μm, capacity on one side is 300GB, 3TB in total
It is.

FIGS. 15A and 15B show a semiconductor laser according to the fourth embodiment. This semiconductor laser 46
Is a beam-scanning semiconductor having a substrate 460 with an upper electrode 461 formed on the upper surface, a lower electrode 462 formed on the lower surface, and an active layer 463 formed in the center. The width of the main portion 464a and the tip portion 464b of the oscillation narrowing portion of the active layer 463 are 3 μm and 5 μm, respectively, and the lengths are 300 μm and 50 μm, respectively. Upper electrode 46
1 is a main part electrode 461a and a pair of left and right tip part electrodes 46
1b and 461b. The oscillation portion of the active layer 463 is narrowed by oscillation narrowing portions 464a and 464b, and the output light beam is scanned left and right by dividing the current into the tip electrodes 461b and 461b or by passing current alternately.
This scanning width can be 1 μm and the scanning frequency can be up to 30 MHz. Tracking of two-step control was performed by the laser beam scanning and the linear motor 45. The generation of the error signal for tracking control was performed by a laser beam wobbling method. That is, the light spot on the recording surface is wobbled about 0.01 μm in proportion to the NA ratio of the collimator lens 4 and the transparent light-collecting medium 6 by scanning the laser beam right and left at 0.03 μm at a high speed (10 MHz). You. As a result, the reflected signal from the recording track is modulated, and the modulated signal is detected in synchronization with the scanning frequency to generate an error signal.

According to the optical disk apparatus 100 according to the fourth embodiment, since information can be recorded on five optical disks 12, the capacity can be increased by 15 TB. In addition,
The optical head 1 shown in FIGS. 1 to 6 may be used. Thereby, the height of the optical head 1 can be reduced to 3 m or less,
The height of the optical disk device can be reduced, and the volume capacity can be increased.

FIGS. 16 (a), (b) and (c) show the fifth embodiment of the present invention.
1 shows a main part of an optical disk device according to an embodiment. This optical disc device 100 is different from the optical disc device 100 of the first embodiment shown in FIG.
Is provided with a plurality of (for example, eight) laser elements that can be independently driven, a plurality of laser beams 3a are emitted from the plurality of laser elements, a plurality of slits 7a are formed in the light shielding film 7C, and the photodetector 24 is formed. Is divided into eight parts, and the other parts are configured in the same manner as in the first embodiment.

As shown in FIG. 16B, the semiconductor laser 2 is an edge emitting semiconductor laser and has an active layer 19a, a p-type electrode 19b, and an n-type electrode 19c. p-type electrode 19b
By the distance d ₁ of the example 15 [mu] m, it has a distance of the laser beam 3a in 15 [mu] m.

As shown in FIG. 6C, the light shielding film 7C
8 slits 7a corresponding to the number of laser beams 3a
I do. The NA of the collimator lens 4 is 0.16, transparent condensing
Is 0.8 in the medium 6 for use, and the distance d between the laser beams 3a is 0.8.
₁Is 15 μm, so that the light
The distance between the pots 9a, that is, the distance d between the slits 7a _Two
Is 3 μm. Array axis direction X 'of slit 7a
Indicates that each slit 7a is directly above an adjacent track.
In the track direction X of the optical disc 12 so that
It is slightly tilted. That is, each neighbor
The vertical spacing of the slit 7a with respect to the recording track is
Track pitch (in this case 0.07 μm) equal to p
It is arranged to become. Track direction X
The tilt angle of the lit 7a in the array axis direction X 'is 23 milliradians.
This tilt is the tilt of the support in the laser array.
Photolithography during formation for tilt and slit arrays
It is adjusted by the adjustment.

Next, the operation of the optical disk device 100 according to the fifth embodiment will be described. When the plurality of laser beams 3a are emitted from the semiconductor laser 2, the plurality of laser beams 3a from the semiconductor laser 2 are shaped into a parallel light beam 3b by the collimator lens 4, and then the polarization beam splitter 22 and the 1/4 wavelength The light passes through the plate 23 and enters the first focal point Fa of the incident surface 6a of the transparent light-collecting medium 6.
When passing through the quarter-wave plate 23, the parallel light beam 3b is changed from linearly polarized light to circularly polarized light by the quarter-wave plate 23. First focal point Fa of incident surface 6a of transparent light-collecting medium 6
The parallel light beam 3b of the circularly polarized light incident on the reflecting surface 6b is refracted and reaches the reflecting surface 6b, and is formed on the reflecting surface 6b.
The light is reflected by A and condensed on the second focal point Fb of the spot forming surface 6c. A plurality of minute light spots 9a are formed on the spot forming surface 6c. A plurality of near-field lights 9b ooze out of the transparent light-collecting medium 6 from the plurality of slits 7a below the plurality of light spots 9a, and the near-field light 9b propagates to the recording layer 121 of the optical disk 12 to perform optical recording. Alternatively, light regeneration is performed. The reflected light reflected by the optical disk 12 reverses the path of the incident light, is reflected by the reflection layer 7A formed on the reflection surface 6b of the transparent light-collecting medium 6, and is separated from the incident beam by the polarization beam splitter 22. After being condensed, the condenser lens 26
Is focused on the eight-divided photodetector 24.

According to the optical disk device 100 of the fifth embodiment, eight independently modulating near-field lights 9b from eight slits 7a simultaneously record eight recording tracks independently. -Reproduction is possible, and the transfer rate of recording and reproduction can be increased eight times. The length of the array of the slits 7a is about 20 μm, and the track bending therebetween is 0.007 μm, which is 1/1 of the track width.
Since it is about 10, the track shift due to this is negligible. Further, the number of slits 7a is not necessarily limited to eight, and can be increased or decreased depending on the application. In addition, as the transparent light-collecting medium 6, those shown in FIGS. 1 to 6 may be used.

[0055]

As described above, according to the present invention,
Since the optical axis of the laser beam from the light condensing means can be bent almost vertically by the reflecting surface which is a part of the spheroidal surface, the light axis of the light condensing means should be arranged almost parallel to the spot forming surface. Is possible, and downsizing in the height direction can be achieved. Also, since the numerical aperture inside the transparent condensing medium can be increased, the light spot formed on the spot forming surface can be miniaturized, and the light spot is shielded by a light shielding film having slits. A near-field light spot smaller than the light spot formed on the formation surface can be obtained, and high recording density can be achieved. In addition, by making the shape such that the laser beam is perpendicularly incident on the incident surface of the transparent light-condensing medium, the occurrence of chromatic aberration can be prevented.

[Brief description of the drawings]

FIG. 1A is a diagram showing a main part of an optical head according to a first embodiment of the present invention, and FIG. 1B is a bottom view thereof.

FIG. 2 is a diagram showing a detailed shape of a transparent light-collecting medium according to the first embodiment.

FIGS. 3A to 3A are diagrams illustrating a method of forming a light-shielding reflection film according to the first embodiment.

FIGS. 4A and 4B are diagrams showing modified examples of the light-shielding reflection film according to the first embodiment.

FIG. 5 is a diagram showing a main part of an optical head according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a main part of an optical head according to a third embodiment of the present invention.

FIG. 7A is a diagram showing a main part of an optical head according to a fourth embodiment of the present invention, and FIG. 7B is a bottom view thereof.

8A is a diagram showing an optical disc device according to the first embodiment of the present invention, and FIG. 8B is a cross-sectional view taken along line AA of FIG.

FIG. 9 is a cross-sectional view illustrating details of the optical disc according to the first embodiment.

10A is a longitudinal sectional view of the optical head according to the first embodiment, and FIG. 10B is a transverse sectional view.

FIG. 11 is a sectional view of the piezoelectric element according to the first embodiment.

FIG. 12 is a perspective view of an optical disk device according to a second embodiment of the present invention.

FIG. 13 is a perspective view of an optical disc device according to a third embodiment of the present invention.

FIG. 14 is a sectional view of an optical disc device according to a fourth embodiment of the present invention.

FIGS. 15A and 15B are views showing a semiconductor laser according to a fourth embodiment.

16A is a diagram showing a main part of an optical disk device according to a fifth embodiment of the present invention, FIG. 16B is a diagram showing the semiconductor laser, and FIG. 16C is a diagram showing the light shielding film thereof. is there.

17A is a diagram showing a conventional optical disk device, and FIG.
Is a diagram showing the operation at the time of reproduction.

FIG. 18 is a diagram showing another conventional optical disk device.

19 is a diagram showing the relationship between the refractive index n and NA in FIG.

FIG. 20 is a diagram showing a conventional optical head.

[Explanation of symbols]

Reference Signs List 1 optical head 2 semiconductor laser 3a, 3b, 3c, 3c ', 3d, 3d', 3e, 3
e 'Laser beam 4 Collimator lens 4' Condensing lens 5 Prism 6 Transparent condensing medium 6a Incident surface 6b Reflective surface 6c Spot forming surface 6c 'Area near slit 6d Bottom surface 7A Reflective film 7B Light-shielding reflective film 7C Light-shielding film 7a Slit Reference Signs List 8 optical disk 9a optical spot 9b near-field light 12 optical disk 12a groove 13 tracking direction 14 linear motor 15 suspension 16 optical head drive system 17 signal processing system 18 flying slider 18a spot forming surface 18b groove 19a active layer 19b p-type electrode 19cn type Electrode 20 Holder 22 Polarizing beam splitter 23 Quarter wave plate 24 Photodetector 25 Head case 26 Condensing lens 33 Suspension 33a Rotating shaft 37C Holder 41 Piezoelectric element 43 Rotary linear motor 44 Rotating shaft 45 Rotation Type linear motor 45a movable piece 45b yoke 45c electromagnet 46 semiconductor laser 70 photoresist film 71 Ti film 100 optical disk device 120 plastic substrate 121 recording layer 200 fixing unit 201 optical fiber 410 electrode terminal 411 electrode film 412 multilayer PZT thin film 460 substrate 461 upper electrode 461a main part electrode 461b tip electrode 462 lower electrode 463 active layer 464a oscillation stenosis main portion 464b distance d ₂ distance Fa first focus Fb of the slit of the oscillation stenosis of the distal end 463 active layer d ₁ p-type electrode first 2 focal points L major axis of spheroid X track direction X 'array axis direction of slits Y direction orthogonal to track direction P center point p track pitch θe half vertex angle of condensed light θc half vertex angle of incident light

Claims (20)

[Claims] 1. An optical head that forms a light spot by condensing laser light, wherein: a laser light emitting means for emitting the laser light; and a light collecting means for condensing the laser light from the laser light emitting means. A part of a spheroid having two focal points at a first point where the laser light is condensed by the light condensing means and a second point where the light spot is formed; A first reflecting surface, a light incident surface on which the laser light from the laser light emitting unit is incident, and a spot forming surface on which the light spot is formed; A transparent light-collecting medium that reflects or refracts the laser light toward the reflection surface after being reflected or refracted at a point and forms the light spot at the second point on the spot formation surface by reflecting the laser light; In a position to block the light spot An optical head comprising: a light-shielding film having a slit in a predetermined direction and provided on a surface of the spot forming surface of the transparent light-collecting medium. 2. The reflection medium, wherein the transparent light-collecting medium is provided at the first point, and reflects the laser light condensed at the first point by the light-condensing means toward the reflection surface. The optical head according to claim 1, further comprising a member. 3. The structure according to claim 1, wherein the incident surface of the transparent light-collecting medium is formed of a part of a concave spherical surface centered on the first point, and the laser light reflected by the reflecting member is incident thereon. Item 3. The optical head according to Item 2. 4. The incident surface of the transparent light-collecting medium comprises a part of a convex spherical surface centered on the first point, and the laser light condensed by the light condensing means is incident thereon. The optical head according to claim 1 having a configuration. 5. The transparent light-collecting medium has the first point on the incident surface, and the laser light condensed on the first point by the light condensing means is reflected on the reflection surface. The optical head according to claim 1, wherein the optical head is configured to bend toward the optical head. 6. The optical head according to claim 1, wherein the spot forming surface of the transparent light-collecting medium has a flat surface. 7. The optical head according to claim 1, wherein said entrance surface of said transparent light-collecting medium is formed of a flat surface. 8. An optical head according to claim 1, wherein said incident surface and said spot forming surface of said transparent light-collecting medium are each formed of a plane and are orthogonal to each other. 9. The light according to claim 1, wherein said incident surface and said spot forming surface of said transparent light-collecting medium are formed of the same plane, and have said first and second points on said plane. head. 10. The spot forming surface of the transparent light-collecting medium has a flat surface, has the first and second points on the flat surface, and the reflecting member and the light shielding film are on the flat surface. 3. An optical head according to claim 2, wherein said optical head comprises a single light-shielding reflection film formed on said substrate. 11. An optical head according to claim 1, wherein said condensing means is a condensing lens. 12. The light according to claim 1, wherein said laser light emitting means comprises a laser light source for emitting said laser light, and a collimating lens for shaping said laser light from said laser light source into parallel light. head. 13. The apparatus according to claim 1, wherein said laser light emitting means includes a laser light source for emitting said laser light, and a deflecting member for deflecting said laser light from said laser light source in a predetermined direction. Light head. 14. An optical disc apparatus having an optical head for forming a light spot by condensing a laser beam and recording or reproducing information on a recording track on a rotating optical disc based on said light spot. A laser beam emitting unit that emits the laser beam; a focusing unit that focuses the laser beam from the laser beam emitting unit; and a laser beam that is focused by the focusing unit. A reflecting surface formed of a part of a spheroid having two focal points at a first point and a second point at which the light spot is formed, and a reflector formed outside, and the laser light from the laser light emitting means; Having a light incident surface and a spot forming surface on which the light spot is formed, and condensed by the light condensing means, and reflected or refracted at the first point toward the reflection surface. A transparent light-condensing medium that reflects the light by the reflector to form the light spot at the second point on the spot forming surface; and a slit that intersects the recording track at a position that blocks the light spot. And a light shielding film provided on the surface of the spot forming surface of the transparent light-collecting medium. 15. The transparent light-collecting media are in close contact with each other,
A first transparent medium and a second transparent medium having the same refractive index, wherein the first transparent medium has the incident surface and the reflection surface, and the second transparent medium is an optical disk. A flying slider that floats and scans on the optical disk with the rotation of
15. The optical disk device according to claim 14, wherein the flying slider has the spot forming surface, and the laser beam emitting means and an optical system required for the recording or the reproduction are arranged on the flying slider. 16. An optical head for forming a light spot by condensing a laser beam, and a plurality of rotating optical disks arranged coaxially at a predetermined interval, wherein the plurality of rotating optical disks are arranged on the plurality of optical disks. In an optical disc device that performs recording or reproduction on a recording track based on the light spot, the optical head includes: a laser beam emitting unit that emits the laser beam; and the laser beam from the laser beam emitting unit is collected. A condensing means, and a part of a spheroid having two focal points, a first point where the laser light is condensed by the condensing means and a second point where the light spot is formed. A reflecting surface on which a reflector is formed, an incident surface on which the laser light from the laser light emitting unit is incident, and a spot forming surface on which the light spot is formed. A transparent light-collecting device that forms a light spot at the second point on the spot forming surface by reflecting the laser light reflected or refracted at the first point toward the reflecting surface by the reflector. And a light-shielding film provided on a surface of the spot forming surface of the transparent light-collecting medium, the slit having a slit in a direction orthogonal to the recording track at a position blocking the light spot. Optical disk device. 17. A spot forming surface having a substantially spheroidal shape having two focal points at a point where laser light is focused and a point where a light spot is formed by the laser light, wherein the light spot is formed. Preparing a transparent light-collecting medium comprising: forming a photoresist layer having an outer diameter having a width smaller than the light spot and a longer length than the light spot on the spot forming surface of the transparent light-collecting medium. Forming a recess by etching a region of the spot forming surface of the transparent light-collecting medium where the photoresist layer is not present at a predetermined depth equal to or less than the wavelength of the laser beam; And forming a light shielding film having an opening corresponding to the outer diameter. 18. The step of forming the photoresist layer comprises:
18. The method of manufacturing an optical head according to claim 17, further comprising a step of forming a photoresist layer for determining an outer diameter of the light-shielding film on an outer green surface of the spot forming surface of the transparent light-collecting medium. 19. The method of manufacturing an optical head according to claim 17, wherein the step of forming the concave portion includes the step of forming a plurality of minute irregularities for light scattering on a seating surface of the concave portion near the photoresist layer. Method. 20. The method of manufacturing an optical head according to claim 17, wherein the step of forming the concave portion includes the step of forming a seating surface of the concave portion near the photoresist layer on an inclined surface.