JP2000215501A - Optical head, optical disk device, and manufacture of the optical head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical head, an optical disk device, and manufacture of an optical head, capable of being small sized, forming highly dense recording, and aimed at preventing generation of color aberration. SOLUTION: A laser beam 3a emitted from a semiconductor laser 2 is arranged in parallel beams 3b by a collimater lens 4, is condensed as a condensed beam 3b' by a condensing lens 4', and is made vertically incident on an incident plane 6a of a transparent condensing medium 6. A condensed beam 3b' made incident from the incident plane 6a is, after being condensed on a first focus Fa, reflected towards a reflecting plane 6b by a light-shielding reflection film 7B, is reflected by a reflection film 7A, and then is condensed on a second focus Fb on a spot-forming plane 6c, and thus a light spot 9a is formed. The light condensed on this light spot 9a leaks out of the transparent condensing medium 6 as a near-field light 9b from the spot forming plane 6c through the pin hole 7a. By having a recording layer 8a of a light disk 8 irradiated with this near-field light 9b, recording/reproducing is executed.

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. 16 (a) and 16 (b) show references (Jpn.
Appl. Phys. , VOL. 35 (1996) p.
443) shows an optical disk device. As shown in FIG. 9A, the optical disc device 190 includes a semiconductor laser 191 for emitting a laser beam 191a and a laser beam 191a from the semiconductor laser 191 for converting a parallel beam 191b.
A coupling lens 192 for shaping the light, and an incident end 193a
A probe 194 for introducing a parallel beam 191b from the coupling lens 192 from the input end 193a, and an output end 193b of the optical fiber 193. And a recording medium 195 which is recorded by the near-field light 191c leaking from the recording medium 191c.

[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. 1B, the recording layer 195a is irradiated with near-field light 191c having a low power that does not cause a phase change by using the same optical head as used for recording. The reflected light 191d therefrom is condensed by a condenser lens 196 to form a photomultiplier tube (hereinafter abbreviated as "photomultiplier").
This is performed by condensing and detecting light at 197.

[0008] FIG. 17 is a schematic diagram of US Pat.
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. 19 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. 18 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. 19, since the parallel laser beam 2b is incident on the optical disk surface in a perpendicular direction, the height of the optical head becomes high, and there is a problem that the optical head cannot be miniaturized. 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 A transparent light-gathering medium, and a light-shielding film provided on the surface of the spot-forming surface of the transparent light-gathering medium, having a fine hole smaller in diameter than the light spot at a position where the light spot is blocked. An optical head characterized by comprising: 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. The light spot formed on the spot forming surface is shielded from light by a light shielding film having minute holes, whereby a near-field light spot smaller than the light spot formed on the spot forming surface is 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,
A light-shielding film provided on a surface of the spot forming surface of the transparent light-collecting medium, the light-shielding film having a minute hole smaller in diameter than the light spot, at a position where the light spot is blocked. An optical disk device 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 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. The light spot formed on the spot forming surface is shielded from light by a light shielding film having minute holes, whereby a near-field light spot smaller than the light spot formed on the spot forming surface is 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; A light shielding film provided on a surface of the spot forming surface of the transparent light-collecting medium, having a micro hole having a diameter smaller than that of the light spot, at a position where the light spot is blocked. An optical disk device 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 almost in parallel with each other, the height direction can be reduced, and the distance between optical disks can be reduced. Further, the half-vertical angle of the laser beam reflected by the reflecting surface is set to the first angle by the focusing means.
Can be increased from the half apex angle of the laser light converged on the spot, so that the light spot formed on the spot forming surface can be miniaturized. The light spot formed on the spot forming surface is shielded from light by a light shielding film having minute holes, whereby a near-field light spot smaller than the light spot formed on the spot forming surface is 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. Prepare a transparent light-collecting medium having a spot forming surface on which a light spot is formed, and form a photoresist layer having an outer diameter smaller than the diameter of the light spot on the spot-forming surface of the transparent light-collecting medium. Forming a concave portion 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, thereby forming a concave portion, and shielding the concave portion from light. A method for manufacturing an optical head is provided, wherein a light shielding film having an opening corresponding to the outer diameter is formed by depositing a material. According to the above configuration, it is possible to form a light-shielding film having an opening having an outer diameter smaller than the light spot formed on the spot forming surface by photolithography.

[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 reflective film 7A is applied to the surface of the reflective surface 6b of the transparent light-collecting medium 6, and a pinhole 7a in the direction Y orthogonal to the track direction X on the optical disk 8 is formed on the surface on the spot forming surface 6c. The 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. Also, depending on the design
By selecting the values of the major axis a and the minor axis b,
While maintaining the distance, appropriately set the distance from the origin of the second focal point Fb
Can be adjusted. This is the degree of freedom to set the ellipsoid
There are two. Let NAi be the NA of condensed light 3e
Then, the diameter D of the light spot 9a at the second focal point Fb_1/2
Is 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 pinhole 7 at a position corresponding to the light spot 9a.
a from the light spot 9a to block the light emitted directly to the outside, and the near-field light 9b through the pinhole 7a.
Is formed. The diameter of the pinhole 7a Do, when the diameter of the light spot 9a and D _1/2, the relationship of Do and D _1/2 is set so that Do <D _1/2. Thereby, near-field light 9b having a diameter of about D _1/2 is formed. In the present embodiment, the diameter D is less than about a fraction of the diameter D _1/2 of the light spot 9a, that is, about 1/10 of the wavelength of the laser light (for example, 50 nm).
I have to. The pinhole does not necessarily have to be circular, but may be rectangular or polygonal. The same effect as a circular pinhole can be obtained by forming the maximum passing length smaller than the diameter of the light spot 9a. Further, the diameter of the pinhole 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 of forming the pinhole. The light-shielding reflection film 7B has a pinhole 7a.
May be subjected to a process of absorbing laser light (for example, a black process), or may be formed of a material that absorbs laser light. As a result, a decrease in the S / N ratio due to the laser light reflected around the pinhole 7a of the light-shielding reflection film 7B can be prevented.

The diameter Do of the pinhole 7a is equal to 1 of the laser wavelength.
Therefore, no propagating light is emitted from the pinhole 7a, and in the track direction X and the direction Y orthogonal to the track direction X, the diameter Do of the pinhole 7a is substantially the same as that of the pinhole 7a. The near-field light 9b having a size several times as large as the near-field light 9b oozes out to a close distance approximately equal to the wavelength. By disposing a medium having a similar refractive index to the near-field light 9b as the refractive index of the transparent light-condensing medium 6, for example, the optical disk 8, in close proximity, the near-field light 9b is
The light propagates and enters the recording layer 8a on the recording layer 8a, and this light enables 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 pinhole 7a That is, in the case of a red laser, the light amount of the laser light passing through the pinhole 7a is the light spot 9a. About 8 of the total power of
%, And about 12% in the case of blue light, and 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 attaching the light-shielding reflection film 7B and a method of forming the pinhole 7a. First, a photoresist film 70 for electron beam exposure is applied to the bottom surface 6d of the transparent condensing medium 6 having a substantially semi-spheroidal shape, and is exposed by an electron beam so as to leave a portion corresponding to the pinhole 7a (FIG. 3 (a)) After development, the bottom surface 6d is anisotropically etched by about 100 ° by dry etching to form a spot forming surface 6c (FIG. 3 (b)). A CF ₄ 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 ° (FIG. 3C), and the photoresist film 70 is dissolved to lift off the Ti film 71 corresponding to the pinhole 7a. (FIG. 3D). Thus, the light-shielding reflection film 7B having the pinhole 7a is formed. The light-shielding reflection film 7B may be a film other than the Ti film as long as it has a light-shielding property and an excellent adhesion to glass. Further, when the present optical head is used for a magneto-optical disk, the use of permalloy for the light-shielding film can increase the strength of the recording magnetic field, so that the number of turns of the coil can be reduced. Therefore, the inductance of the coil is reduced, and high-speed modulation of the recording magnetic field can be performed, so that high-speed recording can be performed. In addition, as the light-shielding reflection film 7B, a reflection film that reflects the incident light 3c may be formed near the first focal point Fa, and a light-shielding film having a pinhole 7a may be formed near the second focal point Fb. In this case, a photoresist film is formed around the portion corresponding to the pinhole 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 pinhole 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. (A) By forming the reflecting surface 6b into a spheroidal shape,
The optical axis of the incident light is converted from a direction substantially parallel to the disk to a direction perpendicular thereto, and the NA inside the transparent light-collecting medium 6 is increased, so that a minute spot can be formed on the spot forming surface 6c. . For example, when the major axis a and the minor axis b of the spheroid are 1.2 mm and 1 mm, respectively, the NA of the condensed beam is 0.86, and the optical head using the condensing system such as the conventional SIL is used. In comparison, the NA can be increased. Further, by further increasing the eccentricity e, the NA can be further increased. Further, since a high NA is obtained, the light spot 9a can be miniaturized. (B) Chromatic aberration does not occur because of the reflection type light collecting system. (C) Since the optical axis can be bent almost perpendicularly by the reflection surface 6b, the optical element can be arranged almost horizontally with respect to the disk surface, and the height of the optical head can be reduced. Thereby, especially when a plurality of optical discs are used one upon another, the capacity can be increased. In addition, since the entire optical disk device can be made thinner, it can be downsized and effective when used as a memory of a portable terminal. (D) The near-field light oozing out of the miniaturized light spot 9a is narrowed down by the pinhole 7a formed in the light-shielding reflection film 7B. Can be reduced to a fraction, so that the recording density can be increased to 20 times or more. (E) Since the diameter of the near-field light 9b can be reduced, the track pitch can be reduced. (F) Even if the near-field light 9b is narrowed by the pinhole 7a having a diameter smaller than the wavelength of the laser beam 3, the light intensity at the central portion of the light propagating from the pinhole 7a does not change, so that high light use efficiency can be obtained. Therefore, the semiconductor laser 2 having a relatively low output of several milliwatts can be used as a light source. Further, since the reflected light from the optical disk 8 also increases in proportion to the light propagated from the pinhole 7a, the Si light detector conventionally used in the conventional optical disk memory can be used for detecting the reproduction light, and the photomultiplier is not used. Thus, the optical head 1 can be reduced in size and weight, and high-speed reading can be performed.

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-condensing medium 6, the surface to be etched is inclined with respect to the incident light by an operation such as inclining the area 6c 'near the pinhole 7a of the spot forming surface 6c, thereby forming a convex or concave conical surface. Shape. Also,
As shown in FIG. 4 (b), when etching the bottom surface of the transparent light-condensing 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. Region 6c 'of light-shielding reflection film 7B near pinhole 7a
Is high, the light intensity reflected by the light shielding reflection film 7B becomes stronger than the signal light returning from the pinhole 7a,
Since the amplification factor of the pre-amplification at the time of signal processing cannot be made large, the S / N decreases. 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 increases, and this heat undesirably affects recording. Therefore, by adopting a structure as shown in FIGS. 4A and 4B, the reflected light 3f is focused on the condenser lens 4 '.
And the S / N can be improved. On the other hand, the reflected light passing through the pinhole 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, a second focal point Fb is formed on the spot forming surface 6c, and a light-shielding film 7C having a pinhole 7a is provided instead of the light-shielding reflection film 7B. The configuration is the same as that of the 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. Note that also in the first and third embodiments, the major axis L of the spheroid with respect to the spot forming surface 6c.
By tilting the first focal point Fa, the first focal point Fa can be separated from the spot forming surface 6c, so that the slider can be easily designed, and other optical systems can be arranged in parallel to the disk surface as in the present embodiment. The same effect 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 in the track pitch of 0.1μ
m, and the depth of the groove portion 12a is about 0.1 μm. The mark length is 0.05 μm and the recording density is 120 Gbi
ts / inch ² and 170 for a 12 cm disc
The recording density was equivalent to the recording capacity of GB, and the recording density was 7.6 times higher than 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 7C having a pinhole 7a is formed on the spot forming surface 18a of the flying slider 18 as shown in FIG.

As shown in FIG. 10A, 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, and is covered by the holder 37C. Has been formed. This piezoelectric element 4
1 scans in the 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. Part of the light of the light spot 9a leaks out of the lower surface of the flying slider 18 as near-field light 9b from the pinhole 7a below the light spot 9a, and the near-field light 9b propagates to the recording layer 121 of the optical disk 12. Optical recording or optical reproduction is performed. 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. Reflected
The light enters the photodetector 24. 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 incident on the photodetector 24, and performs tracking control on the optical head driving system 16 based on the error signal. Do.

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.
% Near-field light 9b through a pinhole 7a having a width of 50 nm.
As a result, the light can be incident on the recording layer 121 of the optical disc 12, and the ultra-high density (170 Gbits / inch ² ) ultra-high density optical recording / reproduction can be performed. In addition, since recording and reproduction can be performed without performing automatic focus control, an automatic focus control mechanism is not required, and the weight of the optical head 1 can be significantly reduced.
The size was 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. For this reason, the weight of the movable part including the movable coil 14B of the linear motor 14 and the suspension 15 can be reduced to 2.0 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 focus shift due to shrinkage is small and the width of the near-field light in the track direction is fixed by the width of the pinhole, the influence of temperature fluctuation is small, so that 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 was 1 mm in height, 2 mm in length / width, and the weight was about 10 mg. Such super lightweight
By using the 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. Also,
This optical disk device can be a stack type similar to the optical disk device of FIG. 14 described later, and a large-capacity optical disk device can be provided. 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.

According to the optical disk device 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. 15A, 15B and 15C 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 capable of independently driving, and a plurality of laser beams 3a are emitted from the plurality of laser elements.
Is formed, and the photodetector 24 is divided into eight parts, and the other parts are configured in the same manner as in the first embodiment.

The semiconductor laser 2 is an edge emitting semiconductor laser as shown in FIG. 2B 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.

The light-shielding film 7C has eight pinholes 7a corresponding to the number of laser beams 3a, as shown in FIG. Since the NA of the collimator lens 4 is 0.16, the NA of the transparent condensing medium 6 is 0.8, and the distance d ₁ between the laser beams 3a is 15 μm, the distance between the light spots 9a on the spot forming surface 6c, ie, The distance d ₂ between the pinholes 7a is 3 μm. The array axis direction X ′ of the pinholes 7a is slightly inclined with respect to the track direction X of the optical disc 12 so that each pinhole 7a is located directly above an adjacent track. That is, the interval between the adjacent pinholes 7a in the vertical direction with respect to the recording track is the track pitch (in this case, 0.07 μm).
It is arranged to be equal to p. Track direction X
The inclination angle of the pinhole 7a in the array axis direction X ′ is 23 milliradians with respect to the inclination angle of the support base in the laser array and the adjustment by photolithography at the time of formation in the pinhole array.

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 pinholes 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 emit light. Recording or optical reproduction is performed. The light reflected by the optical disk 12 reverses the path of the incident light, and is reflected by the reflection surface 6 b of the transparent light-collecting medium 6.
After being reflected by the reflection layer 7A adhered to and separated from the incident beam by the polarization beam splitter 22, the condensing lens 2
The light is condensed on the eight-divided photodetector 24 by 6.

According to the optical disk device 100 according to the fifth embodiment, eight recording tracks are simultaneously recorded independently by eight independently modulatable near-field lights 9b from eight pinholes 7a. Recording and reproduction can be performed, and the transfer rate of recording and reproduction can be increased eight times. The length of the array of the pinholes 7a is about 20 μm, and the track bends between them is 0.007 μm, which is about 1/10 of the track width. Further, the number of pinholes 7a is not necessarily limited to eight, and can be increased or decreased depending on the application. In addition,
1 to 6 may be used as the transparent light-collecting medium 6.

[0054]

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. In addition, since the numerical aperture inside the transparent light-collecting 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 minute holes. A near-field light spot smaller than the light spot formed on the spot forming 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 3D 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.

15A is a diagram illustrating a main part of an optical disk device according to a fifth embodiment of the present invention, FIG. 15B is a diagram illustrating the semiconductor laser, and FIG. 15C is a diagram illustrating the light-shielding film. is there.

16A is a diagram showing a conventional optical disk device, and FIG.
Is a diagram showing the operation at the time of reproduction.

FIG. 17 is a diagram showing another conventional optical disk device.

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

FIG. 19 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 Reflecting surface 6c Spot forming surface 6c 'Area near pinhole 6d Bottom surface 7A Reflective film 7B Light-shielding reflective film 7C Light-shielding film 7a Pinhole 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 formation surface 18b Groove 19a Active layer 19b P-type electrode 19c n-type electrode 20 holder 22 polarizing beam splitter 23 1/4 wavelength plate 24 photodetector 25 head case 26 condenser lens 33 suspension 33a rotation axis 37C holder 41 piezoelectric element 43 rotation type linear motor 44 rotation axis 45 Rotary linear motor 45a Movable piece 45b Yoke 45c Electromagnet 46 Semiconductor laser 70 Photoresist film 71 Ti film 100 Optical disc device 120 Plastic substrate 121 Recording layer 200 Fixed unit 201 Optical fiber 410 Electrode terminal 411 Electrode film 412 Multilayer PZT thin film 460 Substrate 461 Upper part interval Fa first focal point of the distance d ₂ pinholes of the electrode 461a main part electrode 461b tip electrode 462 lower electrode 463 active layer 464a oscillation stenosis main portion 464b oscillation constriction of the distal end 463 active layer d ₁ p-type electrode Fb Second focus L Long axis of spheroid X Track direction X 'Array direction of pinhole Y Direction perpendicular to track direction P Center point p Track pitch θe Half vertex angle of condensed light θc Half vertex of incident light Corner

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 provided on a surface of the spot forming surface of the transparent light-collecting medium, the light-shielding film having a fine hole smaller in diameter than the light spot. 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 diameter smaller than the light spot at a position that blocks the light spot. An optical disc device, comprising: a light-shielding film having a fine hole and provided on a 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. A medium, and a light-shielding film provided on a surface of the spot forming surface of the transparent light-condensing medium, having a fine hole having a smaller diameter than the light spot at a position where the light spot is blocked. Characteristic 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-condensing medium comprising: forming a photoresist layer having an outer diameter smaller than the diameter of the light spot on the spot forming surface of the transparent light-condensing medium; Forming a concave portion by removing an area of the spot forming surface where the photoresist layer is not present by etching at a predetermined depth equal to or less than the wavelength of the laser light, and depositing a light shielding material in the concave portion to adjust the outer diameter. A method of manufacturing an optical head, comprising forming a light-shielding film having a corresponding opening. 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.