JP2000207768A - Optical head and optical disk apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical head and an optical disk apparatus which are small and which can achieve a high recording density. SOLUTION: Laser beams 3a radiated from a semiconductor laser 2 are shaped to be parallel beams 3b by a collimating lens 4, and it is bent at right angles by a return mirror 5 so as to be incident on a condensing hologram 10A. A parallel beam 3c which is incident on the condensing hologram 10A is condensed by the face 6b of a transparent medium 6 to be condensed for condensing, and a light spot 9b is formed on the face 6b to be condensed. Light which is condensed in the light spot 9b is passed through a very small hole 7a from the face 6b to be condensed, so as to be leaked to the outside of the transparent medium 6 for condensing as near-field light 9b. When a recording layer 8a on an optical disk 8 is irradiated with the near-field light 9b, a recording operation and a reproducing operation are performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head and an optical disk apparatus using near-field light, and more particularly to an optical head and an optical disk apparatus which are small in size and capable of increasing the recording density.

[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), and US Patent Publication USP
No. 5,497,359.

FIGS. 15 (a) and 15 (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 incident end 193a having a diameter of 10 μm and an emitting end 193b having a diameter of 50 nm, and is coated with a metal film 194b such as aluminum through a cladding 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. 16 is a cross-sectional view of US Patent Publication 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.

[0010]

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. 17 shows a 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).

Regarding the light collection experiment using the Super SIL, see 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.

Accordingly, it is an object of the present invention to provide an optical head and an optical disk apparatus which are small in size and capable of increasing the recording density.

[0015]

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. A hologram having a light condensing function is attached, and a first surface on which the laser light from the laser light emitting means is incident via the hologram, and the laser light incident on the first surface is condensed. A transparent condensing medium having a second surface on which the light spot is formed, and a transparent condensing medium having a minute hole having a smaller diameter than the light spot at a position blocking the light spot. And a light shielding film provided on the surface of the second surface. According to the above configuration, by using a hologram having a function of condensing laser light, laser light can be condensed without using an objective lens. Further, by using such a hologram, a high NA can be achieved, and a light spot formed on the second surface can be miniaturized. The light spot formed on the second 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 second surface is obtained.

According to another aspect of the present invention, there is provided an optical head for forming a light spot by condensing a laser beam, wherein the laser beam is emitted from the laser beam emitting unit, and the laser beam is emitted from the laser beam emitting unit. A first surface on which laser light is incident and having a function of diffusing the laser light;
A second surface for reflecting the laser light incident on the surface and a hologram having a function of reflecting and condensing the laser light are attached, and the laser light reflected on the second surface is reflected and condensed by the hologram. A transparent condensing medium having a third surface on which the light spot is formed on a different surface, and a light spot having a small hole smaller in diameter than the light spot at a position where the light spot is blocked. And a light-shielding film provided on the surface of the surface of the transparent light-collecting medium on which the light-collecting medium is formed. According to the above configuration, by using a hologram having a function of reflecting and condensing laser light, laser light can be condensed without using an objective lens. Further, by using such a hologram, a high NA can be achieved, and a light spot formed on the transparent light-collecting medium surface can be miniaturized. By shielding the light spot formed on the transparent light-collecting medium surface with a light-shielding film having fine holes, a near-field light spot smaller than the light spot formed on the transparent light-collecting medium surface can be obtained.

According to the present invention, there is provided an optical disk apparatus having an optical head for forming a light spot by converging a laser beam on a rotating disk and recording or reproducing information with the light spot. A laser light emitting unit that emits the laser light,
A first surface on which a hologram having a function of condensing the laser light is attached, and the laser light from the laser light emitting unit is incident through the hologram, and the laser light incident on the first surface is A transparent light-condensing medium having a second surface on which the light spot is formed by condensing light; and a transparent light-condensing medium having a small hole smaller in diameter than the light spot at a position blocking the light spot. And a light shielding film provided on the surface of the second surface of the recording medium. According to the above configuration, by using a hologram having a function of condensing laser light, laser light can be condensed without using an objective lens. As a result,
The size in the height direction is reduced, and the size of the optical disk device can be reduced. In addition, by using a hologram having a laser light focusing function, a high NA can be achieved, and a light spot formed on the second surface can be miniaturized. The light spot formed on the second 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 second surface is obtained.

According to the present invention, there is provided an optical disc apparatus having an optical head for forming a light spot by converging a laser beam on a rotating disk and recording or reproducing information with the light spot. A laser light emitting unit that emits the laser light,
The laser light from the laser light emitting means is incident,
A first surface having a function of diffusing the laser light, a second surface reflecting the laser light incident on the first surface,
A third surface on which a hologram having a function of reflecting and condensing the laser light is attached, and the laser light reflected on the second surface is reflected and condensed by the hologram to form the light spot on a different surface. And a transparent light-collecting medium having a small hole having a diameter smaller than that of the light spot at a position where the light spot is blocked. An optical disc device comprising: a light-shielding film provided. According to the above configuration, by using a hologram having a function of reflecting and condensing laser light, laser light can be condensed without using an objective lens. As a result, the height direction is reduced in size, and the size of the optical disk device can be reduced. Also,
By using a hologram having a function of reflecting and condensing laser light, a high NA can be achieved, and a light spot formed on a transparent condensing medium surface can be miniaturized. By shielding the light spot formed on the transparent light-collecting medium surface with a light-shielding film having fine holes, a near-field light spot smaller than the light spot formed on the transparent light-collecting medium surface can be obtained.

According to the present invention, in order to achieve the above object, a plurality of rotating optical disks arranged coaxially at predetermined intervals, and a laser spot focused on the plurality of optical disks by focusing a laser beam on the plurality of optical disks. In an optical disc apparatus having a plurality of optical heads for recording and reproducing information by using the light spot, the optical head has a laser light emitting unit for emitting the laser light, and a laser light condensing function. A first surface on which the laser light from the laser light emitting means is incident via the hologram, and the laser light incident on the first surface is condensed to form the light spot. A transparent light-collecting medium having a second surface to be formed, and a second hole of the transparent light-collecting medium having a small hole smaller in diameter than the light spot at a position where the light spot is blocked. To provide an optical disk apparatus characterized by comprising a light shielding film provided on the surface. According to the above configuration, by using a hologram having a function of condensing laser light, laser light can be condensed without using an objective lens. As a result, the height direction can be reduced, and the distance between the optical disks can be reduced. In addition, by using a hologram having a laser light focusing function, a high NA can be achieved, and a light spot formed on the second surface can be miniaturized. The light spot formed on the second 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 second surface is obtained.

In order to achieve the above object, the present invention provides a plurality of rotating optical disks arranged coaxially at a predetermined interval, and a laser spot condensing laser light on the plurality of optical disks. In an optical disc device having a plurality of optical heads for forming and recording or reproducing information with this light spot, the optical head comprises: a laser light emitting unit for emitting the laser light; A first surface on which laser light is incident and having a function of diffusing the laser light, a second surface for reflecting the laser light incident on the first surface, and a hologram having a function of reflecting and condensing the laser light Is applied, and the laser light reflected by the second surface is reflected and condensed by the hologram to form the light spot on a different surface.
And a transparent condensing medium having a surface, and a surface of the surface of the transparent condensing medium on which the light spot is formed at a position where the light spot is blocked, the light spot having a small hole having a smaller diameter than the light spot. An optical disk device comprising: a light-shielding film provided on the optical disk device. According to the above configuration, by using a hologram having a function of reflecting and condensing laser light, laser light can be condensed without using an objective lens. As a result, the height direction can be reduced, and the distance between the optical disks can be reduced. In addition, by using a hologram having a function of reflecting and condensing laser light, a high NA can be achieved, and a light spot formed on a transparent condensing medium surface can be miniaturized. By shielding the light spot formed on the transparent light-collecting medium surface with a light-shielding film having fine holes, a near-field light spot smaller than the light spot formed on the transparent light-collecting medium surface can be obtained.

[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 folding mirror 5 for bending the parallel beam 3b at a right angle, and a parallel mirror from the folding mirror 5. A transparent condensing medium 6 on which the beam 3c is incident.

The transparent condensing medium 6 has an incident surface 6a on which a collimated hologram 10A having a condensing function is formed on the surface of which the parallel beam 3c from the folding mirror 5 is incident.
And a converging surface 6b on which the convergent light 3d from the incident surface 6a is converged. On the surface of the light-collecting surface 6b of the transparent light-collecting medium 6, a light-shielding film 7A having a small hole 7a having a smaller diameter than the light spot 9a formed on the light-collecting surface 6b is applied. The shape of the minute hole 7a was a rectangle whose one side is orthogonal to the track direction X of the optical disk 8. Since the recording density is determined by the size of the near-field light in the track direction X, in this case, the recording density in the track direction X is the same as that in the case of the circular micro holes.
On the other hand, the intensity of the near-field light can be made higher than that of the circular shape. However, in terms of ease of processing, circular micropores are excellent, and circular micropores may be used.

The condensing hologram 10A is formed of a binary hologram having concentric concave and convex surfaces.
A volume hologram made of a polymer material may be used.

As the semiconductor laser 2, a distributed non-feedback type laser or a distributed Bragg reflection mirror type laser having small wavelength fluctuation is used. This is the chromatic aberration of the hologram,
Since the fluctuation of the diffraction angle due to the wavelength is large, if a laser having a large wavelength dependence such as an edge emitting laser is used, the light condensing position shifts, and an automatic focus control mechanism for correcting this is required. It is because it becomes large. In the case of a surface emitting laser (VCSEL), it is possible to reduce the wavelength dependency by shifting the center of the gain curve from the oscillation wavelength.

Specifically, the thickness of the transparent light-collecting medium 6 is
0.4mm, diameter of parallel beam 3c is about 6mm, head 1
Is about 1 mm in height. In addition, the collection of the convergent beam 3d
The bundle angle is about 60 degrees and its NA is 0.87. in this case
Of the spot 9a on the light receiving surface 6b_1/2Is
Given by D_1/2= K · λ / (n · NA) where k is a constant determined by the intensity distribution of incident light, and Gaussian
For a beam, it is about 0.5. λ is the wavelength of the light source, n is
This is the refractive index of the transparent light-collecting medium 6, and the light source is Galn.
AlP red laser (wavelength 0.63μm)
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.

The light shielding film 7A is made of titanium (Ti).
It has a thickness (for example, 10 nm) smaller than the wavelength of the laser light, and forms a micro hole 7a at a position corresponding to the light spot 9a to block light emitted directly from the light spot 9a to the outside. The near-field light 9b is formed via the light 7a. The length of the microhole 7a in the track direction X is W,
When the length in a direction Y perpendicular to the track direction X L, 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, the near-field light 9b having a length of W × L is formed. In the present embodiment, the lengths W and L are set to about a fraction of the diameter D _1/2 of the light spot 9a or less, that is, about 1/10 of the wavelength of the laser light (for example, 5
0 nm). Note that the lengths W and L may be smaller than 50 nm in accordance with the progress of the technology for increasing the recording density of the optical disk and the technology for forming micropores. Also, the light shielding film 7A
May be subjected to a process of absorbing laser light (for example, a black color process) around the micro holes 7a, or may be formed of a material that absorbs laser light. Thereby, the light shielding film 7A
Of the S / N ratio due to the laser light reflected around the micro holes 7a can be prevented.

The lengths W and L of the micro holes 7a are set to 1 of the laser wavelength.
Therefore, no propagation light is emitted from the minute hole 7a, and the minute hole 7a is substantially equal to the length W of the minute hole 7a in the track direction X and is equal to the length W in the direction Y orthogonal to the track direction X.
The near-field light 9b, which is about the same as the length L of the a and several times as large in the vertical direction, seeps to a close distance as the wavelength. By disposing a medium having the same refractive index as that of the transparent light condensing medium 6, for example, the optical disk 8, in proximity to the near-field light 9 b, the near-field light 9 b becomes a propagation light in the recording layer 8 a of the optical disk 8. This light allows recording and reading on the recording layer 8a. The amount of the propagated light is represented by the following equation.

(Equation 1) Here, Io: the total power of the laser ω: the radius of the light spot 9a on the light-receiving surface 6b a: the half width of the minute hole 7a That is, in the case of a red laser, the light amount of the laser light passing through the minute hole 7a is the light spot. About 15% of the total power of 9a,
In the case of blue light, it is 20%, and the light collection efficiency can be improved to 100 times or more as compared with the case where a conventional optical fiber is used.

FIGS. 2A to 2D show a method for applying the light-shielding film 7A and a method for forming the fine holes 7a. First, a photoresist film 70 for electron beam exposure is applied to the bottom surface 6c of the transparent light-condensing medium 6, and is exposed by an electron beam so as to leave a portion corresponding to the minute hole 7a (FIG. 2A). Thereafter, the bottom surface 6c is anisotropically etched by about 100 ° by dry etching to form the light-collected surface 6b (FIG. 2B).
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. 2C), and the photoresist film 70 is dissolved to form a T film corresponding to the fine hole 7a.
The i-film 71 is lifted off (FIG. 2D). Thus, the light-shielding film 7A having the fine holes 7a is formed. In addition,
The light-shielding film 7A may be a film other than the Ti film as long as it has a light-shielding property and an excellent adhesion to glass.

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 3a is shaped into a parallel beam 3b by a collimator lens 4, is bent at a right angle by a return mirror 5, and is incident on a condensing hologram 10A. The parallel beam 3c incident on the condensing hologram 10A becomes a convergent beam 3d, and forms a light spot 9a on the converging surface 6b of the transparent condensing medium 6. The laser beam 3d condensed on the light spot 9a passes through the minute hole 7a on the light-shielding film 7A from the converging surface 6b to form a near-field light 9b as a near-field light 9b.
Seeping out of the outside. By irradiating the recording layer 8a on the plastic substrate 8b of the optical disk 8 with the near-field light 9b, information is recorded / reproduced. The light-collected surface 6b 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 above configuration, the following effects can be obtained. (A) By condensing light using the hologram 10A, the light can be condensed at once from the parallel beam 3c without using an objective lens, and the height of the optical head can be reduced. (B) By condensing light using the hologram 10A, high NA light can be condensed.
A small spot of m is obtained. (C) By using a laser with little wavelength dependence as a light source, the problem of chromatic aberration can be avoided even in the case of condensing by a hologram, and an automatic focus control mechanism is not required, and a small optical head can be formed. This makes it possible to reduce the disc spacing when using several optical discs in a stack.
A large number of disks can be stacked, and the capacity can be increased. In addition, since the entire optical disc device can be made thinner, it can be made smaller and more effective when used as a memory for a portable terminal. (D) Since the near-field light 9b oozing out of the miniaturized light spot 9a is narrowed down by the minute holes 7a formed in the light-shielding film 7A, the near-field light 9b is smaller than the convergent light using the conventional Super SIL. Can be made several times smaller, so that the recording density can be increased several times. (E) By using the light-collecting surface 6b as a slider surface for floating traveling, the structure of the optical head can be simplified, and further downsizing and cost reduction can be achieved.

FIGS. 3A and 3B show modified examples of the light shielding film 7A. As shown in FIG. 4A, the light-shielding film 7A is etched by etching the bottom surface of the transparent light-condensing medium 6 by tilting a region 6b 'near the microhole 7a of the light-collecting surface 6b. May be inclined with respect to the incident light to form a convex or concave conical surface. Further, as shown in FIG. 3B, 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. If the reflectance of the region 6b 'near the micro holes 7a of the light shielding film 7A is high, the light shielding film 7A
The intensity of the light reflected by the light source becomes stronger than the signal light returning from the minute hole 7a, and the amplification factor of the pre-amplification at the time of signal processing cannot be increased, so that the S / N is reduced. On the other hand, the light shielding film 7A
If the absorptance is high, the temperature of the portion of the light-shielding film 7A irradiated with the light spot 9a increases, and this heat undesirably affects recording. Therefore, by adopting a structure as shown in FIGS. 7A and 7B, the reflected light 3e does not return to the collimator lens 4 side, and the S / N can be improved. On the other hand, the reflected light passing through the minute hole 7a follows the same path as the incident light 3d 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.

FIGS. 4A and 4B show 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 the incident surface 6a is formed in a convex shape in the first embodiment. By forming the incident surface 6a in a convex shape in this way, the convex incident surface 6a and the condensing hologram 10A are formed.
Since both chromatic aberrations are opposite to the wavelength, both wavelength fluctuations can be canceled out, and even lasers with large wavelength fluctuations, such as edge emitting lasers, do not have automatic focus control. Can be used for

FIGS. 5A and 5B show an optical head according to a third embodiment of the present invention. This optical head 1 is different from the first embodiment in that the incident function and the light condensing function of the incident surface 6a are separated, and the incident surface 6a is formed in a concave spherical shape. The incident light 3d refracted and spread by the surface 6a is reflected by the light-shielding reflection film 7B, and is further reflected and condensed by the reflection surface 6d in which the reflection type hologram 10B is formed around the incident surface 6a. Surface 6b
To form a light spot 9a. In this case, the numerical aperture NA of the reflection hologram 10B is set to the incident surface 6 of the first embodiment.
When the NA is the same as in the case of a, the beam diameter of the parallel beam 3c can be reduced to half or less, so that the size of another optical system such as the folding mirror 5 can be reduced, and the optical head can be further downsized.

FIGS. 6A and 6B show an optical head according to a fourth embodiment of the present invention. This optical head 1 is the same as the third embodiment except that the concave spherical function of the incident surface 6a is replaced by a planar diffusion hologram 10C in the third embodiment. . By replacing the concave spherical incident surface 6a with the diffusion hologram 10C, it becomes possible to cancel the chromatic aberration of the diffusion hologram 10C and the reflection hologram 10B,
A condensing optical head having small wavelength dependence can be obtained, and condensing without automatic focus control can be performed even when a laser having a large wavelength variation such as an edge emitting laser is used.

In the above-described embodiment, the shape of the transparent light-condensing medium 6 on the side facing the optical disk 8 is flat, but a step may be provided, and at least the transparent light-condensing medium 6 may be provided. It is sufficient that the laser beam is focused on any one of the surfaces of No. 6 and a light spot is formed.

FIG. 7A shows an optical disk device according to the first embodiment of the present invention, and FIG. 7B shows A in 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. 8 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. 9A and 9B show the optical head 1 of the optical disk apparatus 100. FIG. 9A is a side view and FIG. 9B is a plan view. The optical head 1 has a flying slider 18 that floats on the optical disk 12, and is made of, for example, AlGalnP and has a wavelength of 630 nm.
Edge-emitting semiconductor laser 2 that emits laser beam 3a, and laser beam 3 that is emitted from semiconductor laser 2.
a collimator lens 4 for shaping a into a parallel beam 3b;
A holder 20 made of a fused silica plate for mounting the semiconductor laser 2 on the flying slider 18, a polarization beam splitter 22 for separating the parallel beam 3 b from the semiconductor laser 2 and the reflected light from the optical disk 12, and a parallel beam from the semiconductor laser 2 A quarter-wave plate 23 for converting the linearly polarized light of the beam 3b into circularly polarized light, a folding mirror 5 for bending the parallel beam 3b from the quarter-wave plate 23 at right angles to the optical disk 12, and
The transparent light-collecting medium 6 having the light-collecting hologram 10A formed on the incident surface 6a and the transparent light-collecting medium 6 in the track direction X
And a photodetector 24 that is mounted on the flying slider 18 and that receives reflected light from the optical disc 12 through the beam splitter 22. Have been placed. Further, the whole is stored in a head case 25, and 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. The transparent light-collecting medium 6 has the same configuration as the transparent light-collecting medium 6 shown in FIG. 1 and is accommodated in an opening 18c formed in the flying slider 18 so as to be movable in a direction Y orthogonal to the track direction X. I have.

As shown in FIG. 9A, the flying slider 18 has a groove 18b for generating a negative pressure. 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 crystal and amorphous in the recording layer 121. 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. 10 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 and is bent at a right angle by the folding mirror 5,
The light is incident on the condensing hologram 10A. Parallel light beam 3b
When passing through the 波長 wavelength plate 23, the 、 wavelength plate 2
3 changes from linearly polarized light to circularly polarized light. The circularly-polarized parallel light beam 3b incident on the condensing hologram 10A is converged as a convergent beam on the converging surface 6b of the transparent condensing medium 6, and a minute light spot 9a is formed on the converging surface 6b. Is formed. A part of the light of the light spot 9a from the minute hole 7a under the light spot 9a is converted into a near-field light 9b by the flying slider 18a.
Leaks to the outside of the lower surface of the optical disk 12, and the near-field light 9b propagates to the recording layer 121 of the optical disk 12 to perform optical recording or optical reproduction. The light reflected by the optical disk 12 follows the path of the incident light in the reverse direction, and is reflected by the polarization beam splitter 22.
The light is reflected in the direction of 0 degrees and 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 of the focused beam on the transparent focusing medium 6 is
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% can be incident on the recording layer 121 of the optical disk 12 as near-field light 9b through the fine hole 7a having a width of 50 nm, and ultra-high density (180 Gbits / inch ² ) ultra-high density optical recording / optical reproduction has become 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 as light as 2 mm in height, 3 mm in width, 6 mm in length, and 0.2 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 is used to generate the tracking control error signal. However, the recording track is made to meander, and the modulation of the reflected light is adjusted to the meander 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 4 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 light-collecting surface 6b of the transparent light-collecting medium 6 and performing magnetic field modulation, magneto-optical recording using a magneto-optical medium is possible. Become. 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, but a surface emitting laser (VCSEL) is used.
Can also be used. In the case of the surface emitting laser, the maximum output in the fundamental mode (TEM00) is about 2 mW, which is 1/10 or less of that of the edge emitting laser. In the present embodiment, the light spot diameter used in the conventional optical disk device is used. Since the light density can be increased by one digit or more, recording is possible even with a surface-emitting type 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 the present 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. 14 to be described later may be used.

FIG. 11 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. 12 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. 11, 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 disc apparatus 100 of the third embodiment, the distance from the optical fiber 201 to the light-condensing surface is as short as about 1 mm, and there is little defocus due to thermal expansion and contraction between them. Since the width of the near-field light in the track direction is constant due to the width of the minute holes, 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 photodetection system are separated from the optical head 1 of the second embodiment,
Had a height of 1 mm, a length / width of 2 mm, and a weight of about 10 mg. 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,
A small optical disk device can be provided. In addition, this optical disk device can be provided as a stack type similar to the optical disk device of FIG. 13 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. 13 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 this optical head 1 is basically the same as that shown in FIG. 9 with a transparent light-collecting medium 6 and an AlGalnN-based laser (630 nm).
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 μm, respectively, and the capacity on one side is 300 GB, and the total is 3 TB.

FIGS. 14A, 14B and 14C show the fifth embodiment of the present invention.
1 shows a main part of an optical disk device according to an embodiment. It should be noted that the illustration of the head case 25 and the like is omitted in FIG. This optical disc apparatus 100 is different from the optical disc apparatus 100 of the first embodiment shown in FIG. 9 in that a plurality of (for example, eight) laser elements capable of independently driving the semiconductor laser 2 are provided. A laser beam 3a is emitted, a plurality of minute holes 7a are formed in a light-shielding film 7A, and a photodetector 24 is divided into eight parts, and the other configuration is the same as that of the first embodiment. Have been.

As shown in FIG. 14B, 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. 14 (c), the light shielding film 7A
It has eight micro holes 7a corresponding to the number of laser beams 3a. The collimator lens 4 has an NA of 0.16, the transparent condensing medium 6 has an NA of 0.8, and the distance d between the laser beams 3a.
Since ₁ is a 15 [mu] m, distance of the light spot 9a on the light collecting surface 6b, i.e., distance d ₂ of microporous 7a is 3μm
I have to. The array axis direction X 'of the minute holes 7a is slightly inclined with respect to the track direction X of the optical disc 12 such that each minute hole 7a is located directly above the adjacent track. That is, the adjacent minute holes 7a are arranged so that the interval in the vertical direction with respect to the recording track is equal to the track pitch (in this case, 0.07 μm) p. The inclination angle of the micro holes 7a in the array axis direction X 'with respect to the track direction X is 23 milliradians, and this inclination is adjusted by adjusting the inclination of the support of the semiconductor laser 2 and the photolithography at the time of forming the light shielding film 7A. .

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, is bent at a right angle by the folding mirror 5, and enters the condensing hologram 10A. 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. The circularly polarized parallel light beam 3b incident on the condensing hologram 10A is converged as a convergent beam on the converging surface 18a of the flying slider 18 to form a plurality of minute light spots 9a. A plurality of near-field lights 9b ooze out of the transparent light-collecting medium 6 from the plurality of micro holes 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 follows the path of the incident light in the reverse direction, is reflected by the return mirror 5 and is separated from the incident beam by the polarization beam splitter 22, and is then divided into eight light detectors 24 by the condenser lens 26. Is collected.

According to the optical disc apparatus 100 of the fifth embodiment, eight recording tracks are independently recorded simultaneously by eight independently modulatable near-field lights 9b from eight micro holes 7a. Recording and reproduction can be performed, and the transfer rate of recording and reproduction can be increased eight times. Note that the micro holes 7
The length of the array a is about 20 μm, and the track bending between them is 0.007 μm, which is 1/10 of the track width.
Therefore, the track deviation due to this can be ignored. Further, the number of the micro holes 7a is not necessarily limited to eight, but can be increased or decreased depending on the application. The optical head 1
3 to 6 may be used.

[0056]

As described above, according to the present invention,
Since the laser light is condensed by using the hologram, the laser light can be condensed without using an objective lens, and downsizing in the height direction can be achieved. Also, since the laser beam is focused using a hologram, a high NA
The light spot formed on the transparent light-collecting medium surface can be miniaturized, and the light spot is shielded by a light-shielding film having minute holes. A small near-field light spot is obtained from the light spot, and a high recording density can be achieved.

[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.

FIGS. 2A to 2D are diagrams illustrating a method of forming a light-shielding reflection film according to the first embodiment.

FIGS. 3A and 3B are diagrams showing a modification of the light-shielding reflection film according to the first embodiment.

FIG. 4A is a diagram showing a main part of an optical head according to a second embodiment of the present invention, and FIG. 4B is a bottom view thereof.

5A is a diagram showing a main part of an optical head according to a third embodiment of the present invention, and FIG. 5B is a bottom view thereof.

FIG. 6A is a diagram showing a main part of an optical head according to a fourth embodiment of the present invention, and FIG. 6B is a bottom view thereof.

FIG. 7A is a diagram showing an optical disc device according to the first embodiment of the present invention, and FIG. 7B is a cross-sectional view taken along line AA of FIG.

FIG. 8 is a sectional view showing details of the optical disc according to the first embodiment.

FIG. 9A is a longitudinal sectional view of the optical head according to the first embodiment, and FIG. 9B is a transverse sectional view.

FIG. 10 is a sectional view of the piezoelectric element according to the first embodiment.

FIG. 11 is a perspective view of an optical disk device according to a second embodiment of the present invention.

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

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

14A is a diagram showing a main part of an optical disk device according to a fifth embodiment of the present invention, FIG. 14B is a diagram showing the semiconductor laser, and FIG. 14C is a diagram showing the light shielding film thereof. is there.

FIG. 15A is a diagram showing a conventional optical disk device, and FIG.
Is a diagram showing the operation at the time of reproduction.

FIG. 16 is a diagram showing another conventional optical disk device.

FIG. 17 is a diagram showing the relationship between the refractive index n and NA in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Optical head 2 Semiconductor laser 3a, 3b, 3c, 3d, 3e Laser beam 4 Collimator lens 5 Folding mirror 6 Transparent condensing medium 6a Incident surface 6b Condensed surface 6b 'Area | region near a micro hole 6c Bottom surface 6d Reflecting surface 7A Light shielding film 7B Light shielding reflection film 7a Micro hole 8 Optical disk 8a Recording layer 8b Plastic substrate 9a Light spot 9b Near field light 10A Condensing hologram 10B Reflection hologram 10C Diffusion holobram 12 Optical disk 12a Groove section 13 Tracking direction 14 Linear motor 15 Suspension Reference Signs List 16 optical head drive system 17 signal processing system 18 flying slider 18a light-receiving surface 18b groove 18c opening 19a active layer 19b p-type electrode 19c n-type electrode 20 holder 22 polarization beam splitter 23 quarter-wave plate 24 photodetector 25 Head case 26 Condenser lens 33 Suspension 33a Rotating shaft 37C Holder 41 Piezoelectric element 43 Rotating linear motor 44 Rotating shaft 45 Rotating linear motor 45a Moving piece 45b Yoke 45c Electromagnet 46 Semiconductor laser 70 Photoresist film 71 Ti film 100 Optical disk Apparatus 120 Plastic substrate 121 Recording layer 200 Fixing unit 201 Optical fiber 410 Electrode terminal 411 Electrode film 412 Multi-layer PZT thin film d ₁ P-type electrode distance d ₂ Micro-hole distance X Track direction X ′ Micro-hole array axis direction Y Track direction The direction perpendicular to the track pitch

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G065 AA11 AB04 AB09 AB22 AB24 AB26 BA01 BA34 BB02 BB10 BB22 BB33 BB44 BB45 BC02 BC03 BC07 BC10 BC19 DA20 5D119 AA02 AA11 AA22 BA01 BB04 CA06 DA01 DA05 FA05 FA17 FA21 JA32 JA44 JA44 JB03 MA06

Claims (18)

[Claims] 1. An optical head that forms a light spot by condensing a laser beam, comprising: a laser beam emitting unit that emits the laser beam; and a hologram having a function of condensing the laser beam. A first surface on which the laser light from the light emitting means is incident via the hologram; and a second surface on which the laser light incident on the first surface is condensed to form the light spot. A transparent light-condensing medium, and a light-shielding film provided on a surface of the second surface of the transparent light-condensing medium having a minute hole having a diameter smaller than that of the light spot at a position where the light spot is blocked. An optical head, comprising: 2. The optical head according to claim 1, wherein said first surface is formed in a convex shape. 3. The transparent light-condensing medium is composed of a first transparent medium and a second transparent medium which are in close contact with each other and have the same refractive index, and wherein the first transparent medium is provided on the first surface. Wherein the second transparent medium has a second surface, and is a flying slider that floats and runs with an air gap between the second surface and the optical disk as the optical disk rotates. The optical head according to claim 1. 4. An optical head that forms a light spot by condensing a laser beam, wherein: a laser beam emitting unit that emits the laser beam; and the laser beam from the laser beam emitting unit is incident on the optical head.
A first surface having a function of diffusing the laser light, a second surface reflecting the laser light incident on the first surface,
A third surface on which a hologram having a function of reflecting and condensing the laser light is attached, and the laser light reflected on the second surface is reflected and condensed by the hologram to form the light spot on a different surface. And a 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 head comprising: a light-shielding film provided. 5. The optical head according to claim 4, wherein said first surface is provided with a hologram having a function of diffusing said laser light. 6. The optical head according to claim 1, wherein said minute hole has a rectangular shape. 7. The optical head according to claim 1, wherein the transparent light-collecting medium has a refractive index larger than 1. 8. The optical head according to claim 1, wherein said hologram is formed from a concavo-convex type binary hologram. 9. An optical head according to claim 1, wherein said hologram is formed from a volume hologram. 10. An optical head according to claim 1, wherein said laser beam emitting means is a distributed non-feedback type laser. 11. An optical head according to claim 1, wherein said laser beam emitting means is a surface emitting laser. 12. The optical head according to claim 1, wherein said second surface is substantially flat. 13. A flying slider according to claim 1, wherein said transparent light-collecting medium is a flying slider which floats with an air gap between said second surface and said optical disk with rotation of said optical disk.
Alternatively, the optical head according to 4. 14. 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 first surface and the third surface, and the second transparent medium has 5. The optical head according to claim 4, wherein said optical head is a flying slider having said second surface, wherein said flying slider is provided with an air gap between said second surface and said optical disk so as to levitate as said optical disk rotates. 15. An optical disk apparatus having an optical head that forms a light spot by condensing a laser beam on a rotating disk and records or reproduces information by using the light spot, wherein the optical head converts the laser beam to light. A first surface on which a hologram having a function of condensing the laser light is attached, and a first surface on which the laser light from the laser light emitting device is incident via the hologram; A transparent condensing medium having a second surface on which the laser light incident on a surface is condensed to form the light spot; and a small hole having a diameter smaller than the light spot at a position blocking the light spot. An optical disc device, comprising: a light-shielding film provided on the surface of the second surface of the transparent light-collecting medium. 16. An optical disk apparatus having an optical head that forms a light spot by condensing a laser beam on a rotating disk and records or reproduces information using the light spot. Laser light emitting means for emitting, the laser light from the laser light emitting means is incident,
A first surface having a function of diffusing the laser light, a second surface reflecting the laser light incident on the first surface,
A third surface on which a hologram having a function of reflecting and condensing the laser light is attached, and the laser light reflected on the second surface is reflected and condensed by the hologram to form the light spot on a different surface. And a 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 disc device comprising: a light-shielding film provided. 17. A plurality of rotating optical discs arranged coaxially at predetermined intervals, and a laser spot formed on the plurality of optical discs by condensing a laser beam. In an optical disk device having a plurality of optical heads for performing recording or reproduction, the optical head is provided with a laser light emitting unit that emits the laser light, and a hologram having a function of condensing the laser light is attached to the optical head. A first surface on which the laser light from the light emitting means is incident via the hologram; and a second surface on which the laser light incident on the first surface is condensed to form the light spot. A transparent light-condensing medium, and a light-shielding film provided on a surface of the second surface of the transparent light-condensing medium having a minute hole having a diameter smaller than that of the light spot at a position where the light spot is blocked. Preparation Optical disc apparatus characterized by. 18. A plurality of rotating optical discs arranged coaxially at predetermined intervals, and a laser spot formed on the plurality of optical discs by condensing a laser beam. In an optical disc device having a plurality of optical heads for performing recording or reproduction, the optical head is a laser beam emitting unit that emits the laser beam, and the laser beam from the laser beam emitting unit is incident thereon,
A first surface having a function of diffusing the laser light, a second surface reflecting the laser light incident on the first surface,
A third surface on which a hologram having a function of reflecting and condensing the laser light is attached, and the laser light reflected on the second surface is reflected and condensed by the hologram to form the light spot on a different surface. And a 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 disc device comprising: a light-shielding film provided.