JP2002352468A - Optical head and optical disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical head and disk device that can improve the data transfer rate in a small size and high in recording density. SOLUTION: The laser beam 3 from a semiconductor laser 2 is made a parallel beam 5 by a collimator lens 4 and enters the 1st surface 6a of the transparent condensing medium 6. The laser beam 5 entering the 1st surface 6a is reflected on the reflector film 7 formed on the outer surface of the 2nd surface 6b and focused on the 3rd surface 6c to form a light spot 9. Light focused in the light spot 9 leaks out as a near field light and transmitted to the recording medium 8 for optical recording or reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head and an optical disk device, and more particularly, to an optical head and an optical disk device in which a light spot is miniaturized.

[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), but the performance of a computer and the definition of a display device have been increased. With the increase in capacity, an increase in capacity is increasingly required.

[0003] The recording density of an optical disc is basically controlled by the size of a light spot formed on a recording medium.
When condensing with an objective lens, the diameter (light spot diameter) D at which the light intensity of the light spot is halved
_1/2 is given by the following equation (1), and the track width is almost equal to this. D _1/2 = kλ / (n · NA) (1) where, k: proportional constant depending on the intensity distribution of the light beam (usually about 0.5) λ: wavelength n: refraction of the medium at the light spot position Rate (usually air,
It is almost 1. ) NA: numerical aperture of objective lens

Since the NA of an objective lens used in a conventional optical disk is about 0.5, D _1/2 is about the wavelength. As can be seen from the above equation (1), in order to obtain a minute light spot, it is effective to shorten the wavelength and increase the NA of the objective lens, and various development efforts are being made. For DVDs, the wavelength is reduced to 0.65 μm, and the NA of the objective lens is increased from 0.45 for CDs to 0.6, which achieves approximately four times the density of DVDs compared to CDs. did it. Regarding the wavelength, lasers that emit green and blue light are being vigorously developed. On the other hand, when the NA is set to 0.6 or more, the influence of the signal intensity fluctuation due to the tilt of the optical disk becomes large, and it is difficult to further increase the NA by the conventional optical recording method using a plastic substrate. For this reason, the light is not passing through the plastic substrate, but is shifting from the opposite direction to the direction of condensing light on the recording layer formed on the plastic substrate.

In the optical recording system in which light is focused on the recording layer without passing through a plastic substrate, the following two systems using near-field light have recently been proposed as means for drastically reducing the diameter of a light spot. . In each of these, the technology for increasing the resolution of a microscope is applied to optical recording.

In the first method, near-field light leaking from the tip of an optical probe whose tip is tapered and polished (to several tens of nanometers or less) is used for recording. In this method, processing of the probe is difficult and unstable, the probe is vulnerable to mechanical shock, the life is short, and the light use efficiency is 1/100.
There are many problems such as low as 0 or less, and many improvements are required for practical use.

In the second method, a hemispherical lens (SolidImmersi) made of a transparent medium having a high refractive index is provided near the focal point of the objective lens.
By placing an on lens (hereinafter abbreviated as “SIL”), a minute light spot is formed at the center of the bottom of the SIL, and optical recording is performed using the spot. It can be said that the technology is relatively more feasible than. This S
Inside the IL, the light wavelength becomes shorter in inverse proportion to the refractive index of the SIL, so that the light spot also becomes smaller in proportion thereto. Most of the light condensed on this light spot is totally reflected toward the hemispherical surface of the SIL, but part of the light leaks as near-field light near the light spot outside the SIL. When a recording medium having a refractive index similar to that of the SIL is arranged near (at a distance sufficiently smaller than the wavelength of light), near-field light couples with this medium to become propagating light that propagates in the medium.
Recording on a medium using this light enables high-density recording. However, since the aberration of the objective lens remains as it is, it is necessary to suppress the aberration of the objective lens sufficiently low. There are two types of light collection methods using the SIL, which will be described below.

FIG. 13 shows an optical head of a first type. The optical head 50 includes an objective lens 5 that collects the parallel light 51.
2 and a hemispherical SIL 5 arranged such that the bottom surface 54a is orthogonal to the convergent light 53 from the objective lens 52.
And 4. When the parallel light 51 enters the objective lens 52, the parallel light 51 is condensed by the objective lens 52, and the convergent light 53 from the objective lens 52 is converted to the hemispherical surface 5 of the SIL 54.
4b, and is condensed at the center of the bottom surface 54a of the SIL 54 to form a light spot 55. The diameter of the light spot 55 in the optical head 50 is reduced in inverse proportion to the refractive index of the SIL 54. The recording medium 5 is
When 6 is brought closer, the near-field light near the light spot 55 becomes propagation light and enters the recording medium 56.

FIG. 14 shows a second type of optical head. 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.
54. The SIL 54 is disposed so as to refract the convergent light 53 from the objective lens 52 and further condense it. By configuring the SIL 54 such that the parallel light 51 condenses at a position r / n (r is the radius of the SIL) from the center 54c of the hemispherical surface 54b (referred to as a Super SIL structure), the spherical aberration due to the SIL 54 is reduced. Small and
The numerical aperture inside the SIL 54 is shown in FIG.
The numerical aperture can be increased to n times the numerical aperture of 2, and the light spot 55 can be further miniaturized. That is, the light spot is miniaturized as in the following equation (2). D _1/2 = kλ / (n · NAi) = kλ / (n ² · NAo) (2) where, NAi: numerical aperture inside SIL 54 NAo: NA of light incident on SIL 54

However, the NA of the light incident on the Super SIL 54, that is, the maximum value θmax of the incident angle θ and SI
The refractive index n of L5 has a reciprocal relationship, and both cannot be increased independently.

FIG. 15 shows that Mr. Suzuki has proposed the Asia-Pasific Data St.
orageConference (Taiwan, '97 .7.) analyzed at # OC-1 and the refractive index n of Super SIL54
And the relationship between NAo and NAo (hereinafter referred to as “conventional example 1”).
As can be seen from the figure, as the refractive index n of the SIL increases, the maximum value NAomax of the incident light NAo gradually decreases. This is because NAo is greater than the maximum value NAomax.
When the angle of incidence increases and the incident angle further increases, the light
This is because the light spot 55 at the position of the recording medium 56 rather spreads because the light directly enters the recording medium 56 without passing through the L54. For example, when the refractive index n = 2, NAoma
x 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).

BDTerris et al. In Appl. Phys. Lett., Vol. 68, ('9
6), p. 141. (hereinafter referred to as "Conventional Example 2"). According to this report, S with a refractive index n = 1.83
Place the upper SIL between the objective lens and the recording medium,
By condensing a laser beam having a wavelength of 0.83 μm, the laser beam is set to 0.1.
A light spot diameter of 317 μm was obtained. That is, D
_Although light collection equivalent to _1/2 = λ / 2.3 is achieved, the NA in this case is 0.4, and n · NAmax is about 0.73. Also, using this system, the recording density several times higher than the conventional one (3.
8 × 10 ⁸ bits / cm ² ).

FIG. 16 shows an optical disk apparatus described in US Pat. No. 5,497,359 (hereinafter referred to as "conventional example 3"). The optical disk device 500 includes an optical disk 501 having a recording layer 501b formed on a plastic substrate 501a, and an optical disk
01, a motor 504 rotating the shaft 01 by a shaft 503, a flying slider 505 made of a transparent medium which floats and travels on the recording layer 501b of the optical disk 501, and a flying slider 50
5, a hemispherical SIL 54, an optical system for shaping and condensing the light beam of the semiconductor laser, and detection for generating signals and data signals for automatic focus control and tracking control from reflected light from the optical disk 501. Optical system 5
10 and an arm 506A supporting the detection optical system 510
And the floating slider 50 attached to the arm 506A.
5 and a voice coil motor (VCM) 507 that is provided on the base 502 and drives the arm 506A to simultaneously access and track the SIL 54 and the detection optical system 510.

FIG. 17 shows details of the SIL 54 and the flying slider 505 of the third conventional example. Flying slider 505
Is formed of a transparent medium having the same refractive index as the SIL 54. The flying slider 505 is a hemispherical SIL5
4, the laser beam is condensed on the lower surface of the flying slider 505 to form the light spot 55, so that the flying slider 505 and the SIL 54
r SIL is configured.

FIG. 18 shows a detection optical system section 510 of the third conventional example.
The details are shown below. The detection optical system section 510 employs the most common conventional optical system, and is not particularly improved in accordance with the SIL 54. That is, the detection optical system 510 includes a semiconductor laser 511 that emits a laser beam 511a and an output light 51 from the semiconductor laser 511.
Collimator lens 512 that makes 1a parallel light 511b
A beam splitter 1513 for separating output light 511b from the semiconductor laser 511 and reflected light from the optical disk 501; a mirror 514; and a parallel light 511c from the semiconductor laser 511, which is driven by an actuator 515 and is transmitted onto the optical disk 501. Objective lens 5 for focusing
16A and a photodetector 517 input from a lens 516B after the reflected light from the optical disc 501 is separated from the incident light by a beam splitter 513, and a data signal (DAT) output from the photodetector 517 and a control signal. Signal (FE
S, TES). The SIL 54 has a diameter of 2 mm, which is an appropriate size for manufacturing. In this case, the beam diameter at the position of the objective lens 516A is about 4 mm. Therefore, each optical system component 512, 51 of the detection optical system unit 510
The effective apertures of 3,514, 516A, and 516B need to be 4 mm or more, which is about the same as the beam diameter.

The optical disk device 500 has a VC
Tracking control is performed by one-stage control of only M507, and automatic focus control in which the objective lens 516A is driven by the actuator 515 is performed. Since the depth of focus decreases in inverse proportion to the square of NA and the cube of n, the depth of focus in the case of light collection using the SIL 54 is as small as 0.2 μm or less. On the other hand, since a convergent beam is generated between the objective lens 516A and the SIL 54, this interval expands and contracts due to temperature fluctuation, and thus a defocus occurs. Further, since the oscillation wavelength of the laser fluctuates depending on the temperature, the chromatic aberration of the objective lens 516A also causes a defocus. Therefore, the occurrence of the above-mentioned defocus is prevented by performing high-precision automatic focus control.

In an optical disk apparatus using an SIL for an optical system, an optical head runs close to and floats on a recording medium, so that it is suitable to use an optical disk as a fixed or non-replaceable optical disk. Conflicts. For this reason, not only the recording capacity and the data transfer rate, but also a high volume recording density when disks are stacked to form a multi-head / multi-disk is indispensable. In the case of the latest hard disk, since the disk interval is 3 mm or less, it is necessary to reduce the height of the optical head to the same level as the hard disk head (about 2 mm or less).

FIG. 19 shows a structure in response to such a demand for downsizing the optical head.
497,359 discloses an optical head (hereinafter, referred to as "conventional example 4"). This optical head 50 has an SI
The L54, the objective lens 516A, the semiconductor laser and the detection optical system are integrated on the flying slider 505 and run up and down. In the figure, the semiconductor laser and the detection optical system are collectively shown as a single block 520, and the block 520 is attached to the flying slider 50 by the mounting member 521.
5 is attached. Since the distance between the objective lens 516A and the block 520 is shortened to reduce the influence of a temperature change, an automatic focus control mechanism is not required, and the size can be reduced.

On the other hand, a light-weighted conventional optical head is described in the document "Digest of Optical Data Storage ('93) P.93.
(Hereinafter referred to as “conventional example 5”). This optical head employs a separation type optical system in which a semiconductor laser and a detection unit are separated from an objective lens unit and fixed, and only the objective lens unit is driven by a VCM. The tracking is performed by two-stage control using a galvanometer mirror for tracking in a high frequency range. Thereby, the weight of the movable part including the objective lens can be reduced to 7 g including the VCM. Further, the frequency band can be expanded to about 30 kHz (gain is about 80 dB) by tracking by two-stage control.

FIG. 20 shows a conventional optical disk apparatus (hereinafter referred to as "Conventional Example 6") described in the document "Nikkei Electronics (No. 699, P.13, '97 .9.22)". The optical disk device 500 has a separation optical system that employs a galvanometer mirror for tracking.
01, a flying slider 505, a SIL (not shown) mounted on the flying slider 505, an objective lens 530, a rising mirror 531, an arm 532 supporting the flying slider 505, and an arm 532 are driven. VCM 533, fixed optical system 534, and mirror 535 for guiding light from fixed optical system 534 to objective lens 530
And By adopting the separation optical system, as in the fifth conventional example, the weight of the movable portion can be reduced, and the frequency band of tracking can be expanded.

[0021]

However, according to Conventional Examples 1 and 2, the refractive index n of the SIL and the maximum NAmax
Has a reciprocal relationship, the theoretical limit of the product n · NAmax of the two is 0.8 to 0.9, and actually 0.7 to 0.8
And the light spot diameter is large, making it impossible to achieve high density.

Further, according to the optical disk device 500 of the conventional example 3, since the SIL 54 has a diameter of 2 mm, the beam diameter needs to be about 4 mm, and the objective lens 516A has low aberration and low chromatic aberration. Since it is necessary, the lens size (diameter or height) becomes large, and the optical system becomes large. In addition, since a convergent beam is used as a beam incident on the SIL 54, an autofocus control mechanism is required because the convergent point changes due to temperature fluctuation. Accordingly, the weight of the optical head is as heavy as 10 g or more, and the height is as high as about 10 mm.
The interval when overlapping is large, it is difficult to increase the capacity,
There is a problem that the volume capacity cannot be increased as compared with the magnetic hard disk. That is, it is possible to reduce the entire optical system by reducing the diameter of the SIL 54, but there is a limit because the thickness of the flying slider 505 must be reduced at the same time. That is, the thickness of the flying slider 505 is determined by the distance r / n from the center to the focal point.
, But using a medium with a refractive index of 2,
When the radius is 0.5 mm, the thickness of the flying slider 505 is 250 μm, which is almost the limit thickness for maintaining mechanical strength,
It is difficult to make the radius of the SIL 54 smaller than this. Also, when the weight of the optical head is as heavy as 10 g or more,
There is a problem that high-speed tracking cannot be performed and the data transfer rate cannot be increased.

According to the optical head 50 of the conventional example 4,
Actually, it is difficult to reduce the size of the optical head 50 and an automatic focus control mechanism is required. Therefore, similarly to the third conventional example, the height of the optical head 50 is increased, and it is difficult to increase the capacity. That is, an optical system for generating a signal for tracking control and a data signal is actually required. Further, since the optical systems are stacked in the vertical direction, the size of the optical system is increased because the rigidity of the mounting member 521 must be maintained. A nearby height is required. Furthermore, since the optical system of the optical head 50 is a finite system, even if the distance from the semiconductor laser to the objective lens 516A is almost the same as the distance from the objective lens 516A to the focal point, it is almost 2 when focusing a parallel beam. If the magnification, that is, the NA on the image plane side is about 0.5, the objective lens 516A whose NA is close to 1 is required, which is unrealistic. This N
In order to reduce the problem A, the distance from the semiconductor laser to the objective lens 516A must be increased, and the size of the optical head increases. In addition, although automatic focus control is not required, since the optical system is a finite system, it is easily affected by expansion and contraction due to temperature fluctuation of the optical system support member.
It is also necessary to correct the defocus due to laser wavelength fluctuation,
In practice, it is difficult to remove the automatic focus control mechanism.

Further, according to the optical head of the fifth conventional example, there is a problem that the galvanomirror has a limitation in a high frequency range and cannot achieve a high data transfer rate. That is, the track width becomes narrower in proportion to the miniaturization of the light spot, and accordingly, higher-speed and higher-performance tracking control is required. The track width is about 70% of the normal light spot diameter D _1/2 as seen on a DVD. Therefore, D _1/2
Is 0.31 μm, the track width is 0.3 mm.
When a blue laser (410 nm) is used, the track width becomes 0.1 μm or less. On the other hand, the tracking accuracy usually needs to be performed at about 1/10 of the track width. In other words, tracking with an accuracy of ± 0.01 μm is required. In addition, since tracks are previously formed on the optical disk by stamping, track eccentricity of ± several tens of microns occurs during the process. In order to track this track with an accuracy of ± 0.01 μm, a tracking error of ± 0.01 μm is detected, and a tracking of ± several tens of microns is performed. A gain of 80 dB is required as a control system. Become. Further, since the tracking control system is a secondary system, and the band is extended at -40 dB / digit, the rotational speed is set to a normal 3600 rpm, and in order to perform tracking of 0.01 μm on this rotating disk, about 200 kHz is required. Is required.
That is, even if the galvanometer mirror is used as described above, the band is 30 kHz, and it is difficult to perform tracking by one-stage control. The rotation speed is reduced by one digit or more, or a lighter weight and higher performance than the galvanometer mirror are used. Needs to be used. It goes without saying that a higher data transfer rate is required along with the increase in density, but lowering the rotation speed causes a problem in that the data transfer rate is reduced in proportion thereto.

Further, according to the optical disk device 500 of the sixth prior art, the beam diameter is set to 4 to 5 mm in order to reduce the beam position shift due to the movement of the optical head. The height is close to 10 mm, and when the optical disks 501 are stacked, a large interval must be taken, and it is difficult to increase the capacity. The wavelength is 68 nm
Despite being about 20% shorter than the above example, the track pitch is 0.34 μm, which is larger than the theoretical spot diameter of 0.2 μm in this system. The advantages of SIL have not been fully exploited.

Each of the above-mentioned problems arises from the fact that the SIL alone cannot sufficiently condense light and requires two-stage light condensing in combination with the objective lens. Problem.

Accordingly, it is an object of the present invention to provide an optical head and an optical disk apparatus which are small in size, enable high recording density, and improve a data transfer rate.

[0028]

In order to achieve the above object, the present invention provides a laser light emitting means for emitting laser light,
A first surface on which the laser light from the laser light emitting means is incident, a second surface for reflecting the laser light incident on the first surface, and the laser light reflected on the second surface being condensed An optical head comprising: a third surface on which a light spot is formed; and a transparent light-collecting medium for performing recording or reproduction with near-field light oozing from the third surface. . In order to achieve the above object, the present invention provides an optical disc device comprising: a rotating optical disc; and an optical head for recording or reproducing information by irradiating the optical disc with a laser beam. A laser light emitting unit for emitting light, a first surface on which the laser light from the laser light emitting unit is incident, a second surface for reflecting the laser light incident on the first surface, and a second surface. A transparent converging medium having a third surface on which the reflected laser light is condensed to form a light spot, and performing recording or reproduction with near-field light oozing from the third surface. An optical disk device characterized by the above-mentioned features is provided. In order to achieve the above object, the present invention provides a plurality of rotating optical discs arranged coaxially at predetermined intervals, and irradiates a laser beam onto the plurality of optical discs to record or reproduce information. In an optical disc apparatus having a plurality of optical heads, the optical head comprises: a laser beam emitting unit for emitting the laser beam; a first surface on which the laser beam from the laser beam emitting unit is incident; and a first surface. And a third surface on which the laser light reflected by the second surface is focused and the light spot is formed by condensing the laser light reflected by the second surface, and oozes out from the third surface. And a transparent light-collecting medium for performing recording or reproduction with near-field light. The present invention
In order to achieve the above object, in a rotating optical disk, an optical disk device that irradiates a laser beam onto the optical disk to record or reproduce information, a semiconductor laser that emits the laser beam, and the laser from the semiconductor laser. Light is incident thereon, and the incident laser light is condensed and a transparent condensing medium having a surface on which a light spot of the laser light is formed, and an output position of the laser light from the semiconductor laser is displaced. Thereby, a light spot displacing means for displacing a position where the light spot is formed with respect to the transparent condensing medium in a predetermined tracking direction, and a light provided with at least the semiconductor laser and the transparent condensing medium. Light, comprising: a head; and an optical head moving means for moving the optical head in the predetermined tracking direction. To provide a disk apparatus.

[0029]

FIG. 1 shows an optical head according to a first embodiment of the present invention. The optical head 1 includes a semiconductor laser 2 for emitting a laser beam 3 and a collimator lens 4 for shaping the output light 3 of the semiconductor laser 2 into a parallel beam 5.
A transparent condensing medium 6 for condensing the parallel beam 5, a reflective film 7 formed on a surface of a second surface 6b described later of the transparent condensing medium 6, and a transparent condensing medium 6 Third surface 6 described later
and a recording medium 8 arranged in the vicinity of the recording medium c.

The transparent condensing medium 6 has a first surface 6a on which the parallel beam 5 is incident, and a laser beam 5 incident on the first surface 6a.
And a third surface 6c on which the laser beam reflected by the second surface 6b is focused. Second surface 6b
The reflective film 7 formed on the surface of the first surface 6a reflects the laser beam 5 incident on the first surface 6a to form a light spot 9 on the third surface 6c.

The second surface 6b uses a part of the paraboloid of revolution to increase the NA inside the transparent light-collecting medium 6 and to form a minute light spot 9 on the three surfaces 6c.
The main axis of the section (6b) of the paraboloid of revolution is the x-axis, and the vertical axis is y
Taking the axis, the focal position is (p, 0), and the cross section (6
b) is represented by y ² = 4 px (3). When the light is condensed inside the transparent condensing medium 6 using a paraboloid of revolution, it is possible in principle to collect light with no aberration (Optical: Hiroshi Kubota, Iwanami Shoten, P.283). One light-collecting surface enables light to be focused on the minute spot 9. The light spot diameter D _{1/2 in} this case is given by the following equation (4) as in the case of the SIL. D _1/2 = λ / (n · NAi) (4) where, NAi: numerical aperture inside the transparent light-collecting medium 6

Next, the operation of the optical head 1 will be described.
When a laser beam 3 is emitted from the semiconductor laser 2, the laser beam 3 is shaped into a parallel beam 5 by a collimator lens 4 and is incident on a first surface 6 a of a transparent focusing medium 6. The laser beam 5 incident on the first surface 6a is reflected by the reflection film 7 formed outside the second surface 6b, and is reflected on the third surface 6c.
It converges upward and forms a light spot 9 on the third surface 6c.
The light focused on the light spot 9 leaks out as near-field light and propagates to the recording medium 8, where optical recording or optical reproduction is performed. In order to form a light spot on the third surface 6c, the second surface may be formed such that the third surface is located within the depth of focus.

According to the optical head 1 having the above configuration, the following effects can be obtained. (B) p at the focal position of the paraboloid of revolution is p = 0.125 mm
And the upper end of the paraboloid of revolution is (x, y) = (2 mm, 1 m
m), the convergence angle from the upper end is 60 degrees or more, and the NA of the third surface 6c is 0.98, which is 1.6 times or more the NA of conventional DVD = 0.6. I was able to. (B) Since a high NA is obtained, the light spot 9 can be miniaturized. (C) Chromatic aberration does not occur due to reflection type light collection. (D) The optical system according to the present embodiment is a so-called infinite system, that is, the laser beam 5 between the collimator lens 4 and the transparent light-condensing medium 6 is parallel, so that the focal position shift due to temperature fluctuation is small. . (E) Since the optical system can be arranged along the recording medium 8, the height of the optical head 1 can be reduced, and the capacity can be increased when a plurality of optical disks are used. Note that a reflective hologram such as a volume hologram or a binary hologram having unevenness may be used for the reflective layer 7.

FIG. 2 shows an optical head according to a second embodiment of the present invention. The optical head 1 has a second surface 6b of a transparent medium for condensing light, and uses a reflection hologram such as a volume hologram or an uneven binary hologram for a reflection layer 7; The configuration is the same as that of the embodiment. The second surface 6 of the transparent light-collecting medium 6
By making a a plane, productivity can be increased.

FIG. 3 shows an optical head according to a third embodiment of the present invention. This optical head 1 uses a part of a spherical surface as the second surface 6b of the transparent light-collecting medium 6, and uses a reflection hologram such as a volume hologram or an uneven binary hologram as the reflection layer 7; Are configured in the same manner as in the first embodiment. When a spherical surface is used for the second surface 6b, the light-collecting performance can be improved by using a reflective hologram for the reflective layer 7, although the light-collecting property is slightly inferior. Note that a metal such as Al may be deposited on the second surface 6b of the transparent light-collecting medium 6 as the reflective layer 7.

FIG. 4A 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 10, a recording layer 121 made of a GeSbTe phase change material is formed on one surface of a disc-shaped plastic plate 120, and the optical disc 1 is rotated via a rotating shaft 11 by a motor (not shown).
2, an optical head 1 for performing optical recording / light reproduction on the recording layer 121 of the optical disk 12, a linear motor 14 for moving the optical head 1 in the tracking direction 13, and a suspension for supporting the optical head 1 from the linear motor 14 side. Fifteen
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 has a tracking direction 1
A pair of fixing portions 14A, 14A provided along 3;
Moving coil 1 moving on a pair of fixed parts 14A, 14A
4B. The optical head 1 is supported by the suspension 15 from the movable coil 14B.

FIG. 5 shows details of the optical disk 12. The optical disc 12 has a higher recording density in response to the miniaturization of the light spot 9 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. 6A and 6B show the optical head 1. FIG. 6A is a side view thereof, and FIG. 6B is a plan view thereof. Optical head 1
Has a flying slider 18 that floats on the optical disk 12, and moves the edge emitting semiconductor laser 19 that emits the laser beam 3 and the edge emitting semiconductor laser 19 on the flying slider 18 in the vertical direction. A piezoelectric element 20 for displacing the light spot 9 in the tracking direction 13 as shown in FIG. 9 '; a collimator lens 4 for shaping the laser beam 3 emitted from the semiconductor laser 19 into a parallel light beam 5; And a fused quartz plate 21 for fixing the collimator lens 4 on the flying slider 18
A polarizing beam splitter 22 for separating the parallel light beam 5 from the semiconductor laser 19 and the reflected light from the optical disc 12; and a quarter-wave plate for converting the linearly polarized light of the parallel light beam 5 from the semiconductor laser 19 into circularly polarized light. 23, a transparent condensing medium 6 for condensing the parallel light beam 5 from the semiconductor laser 19
A reflection layer 7 formed of a metal such as Al on the outside of the second surface 6b of the transparent light-condensing medium 6; and a photodetector 24 for inputting reflected light from the optical disk 12 via a beam splitter 22. Are arranged. 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 condensing 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-gathering medium 6 is similar to the transparent light-gathering medium 6 shown in FIGS.
It has a first surface 6a and a second surface 6b, but the flying slider 18 is made of a transparent medium having the same refractive index as the transparent light-collecting medium 6, and the lower surface 16a of the flying slider 18 corresponds to the third surface 6b. And the flying slider 1
The light spot 9 is formed on the lower surface 16 a of the light source 8.

FIG. 7 shows the back surface of the flying slider 18.
The flying slider 18 has a groove 18b so as to generate a negative pressure in a portion other than the periphery of the light spot 9 formed on the lower surface 18a. The gap between the light spot 9 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 this embodiment, the flying height is about 0.1 μm. In addition,
The lower surface 18a serves as a sliding surface.

FIG. 8 shows the edge emitting semiconductor laser 19 and the piezoelectric element 20. Edge-emitting semiconductor laser 19
Is composed of, for example, AlGalnP and has a wavelength of 630 nm.
Out of the laser beam 3. The active layer 190 of the semiconductor laser 19 is arranged perpendicular to the surface of the optical disk 12. The edge emitting semiconductor laser 19 has a beam divergence angle θh in a plane parallel to the plane of the active layer 190.
(See FIG. 6B) is a beam divergence angle θv in a plane orthogonal to the plane of the active layer 190 at 8 to 10 degrees (see FIG. 6A).
Is less than 1/2 or less than 25 to 30 degrees. On the other hand, the opening of the transparent condensing medium 6 having a paraboloid of revolution has a vertical direction that is １ ／ of the horizontal direction, and by arranging the semiconductor laser 19 as described above, almost no light loss occurs. The laser beam can be made incident on the transparent light-collecting medium 6.
By using the edge emitting type semiconductor laser 19, a small (for example, 0.3 × 0.4 × 0.4 mm) and lightweight (for example, 0.5 mg or less) laser light source can be obtained, and the size and weight of the optical head 1 can be reduced. be able to.

The piezoelectric element 20 includes electrode terminals 200, 200
And a multi-layer PZT thin film (about 20 μm thick) 202 formed between the electrode films 201. The piezoelectric element 20 is formed of the above fused quartz plate 21
, And a semiconductor laser 19 is further superposed thereon. Since the weight of the semiconductor laser 19 is as small as 0.5 mg or less, the resonance frequency of the system supporting the semiconductor laser 19 is set to 30.
0 kHz or more, and a displacement of 0.5 μm or more was obtained at an applied voltage of 5 V between the electrode terminals 200. The light spot 9 on the third surface 6c can be scanned in the tracking direction 13 by the vertical scanning of the semiconductor laser 19 by the piezoelectric element 20.

The optical head drive system 16 modulates the output light of the semiconductor laser 19 with a recording signal at the time of recording, thereby causing a phase change between crystal and amorphous in the recording layer 121, and as a difference in reflectance between them. At the time of recording and reproduction, the output light of the semiconductor laser 19 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 disc 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 disk technology, Radio Technology, p. 95), and this sample servo method uses a staggered mark (Wobbled Tr
ack) is intermittently provided on the track, and an error signal is generated from a change in the reflection intensity from that. The tracking control is performed by two-stage control in which the linear motor 14 is controlled based on a low-frequency range error signal and the piezoelectric element 20 is controlled based on a high-frequency range error signal. 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.

As described above, since the recording signal and the tracking error signal are separated in a time-division manner by adopting the sample servo method, the photodetector 24 does not need to be a split type, and is, for example, 1 mm square. Can be used. Since the photodetector 24 does not need to be a split type, the detection system can be significantly simplified and lightened.

Next, the operation of the optical disk device 10 will be described. The optical disk 12 is rotated at a predetermined rotation speed by a motor (not shown), and the flying slider 18 flies over 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. When the laser beam 3 is emitted from the edge-emitting semiconductor laser 19 by the drive of the optical head drive system 16, the output light 3 of the semiconductor laser 19 is shaped into a parallel light beam 5 by a collimator lens 4 and then a polarization beam splitter. The light passes through the 22 and １ ／ wavelength plate 23 and enters the first surface 6 a of the transparent light-collecting medium 6. Parallel light beam 5
When passing through the 波長 wavelength plate 23, the 、 wavelength plate 2
3 changes from linearly polarized light to circularly polarized light. Circularly polarized parallel light beam 5 incident on the first surface 6a of the transparent condensing medium 6
Are reflected by the reflection layer 7 formed on the second surface 6b and condensed on the lower surface 18a of the flying slider 18. A minute light spot 9 is formed on the lower surface 18a of the flying slider 18.
From the light spot 9, the lower surface 18 of the flying slider 18
Near-field light leaks to the outside of a, and the near-field light propagates to the recording layer 121 of the optical disc 12 to perform optical recording or optical reproduction. The light reflected by the optical disk 12 reverses the path of the incident light, and the second surface 6 of the transparent light-collecting medium 6
b, the light is reflected by the reflective layer 7 formed on the surface b, reflected by the polarization beam splitter 22 in the 90-degree direction, and is incident on 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 disk device 10 having the above configuration,
The following effects can be obtained. (A) The maximum reflection angle on the second surface 6b of the transparent light-collecting medium 6 is
60 degrees, NA of 0.86 is obtained, and as a result,
Pot diameter D_1/2A small light spot 9 of about 0.2 μm was obtained.
High density (19Gbits / inch^Two)
Recording / light reproduction is now possible. (B) Since recording and playback can be performed without performing automatic focus control,
The need for an automatic focus control mechanism is eliminated, and the weight of the optical head 1 is increased.
The width can be reduced and the size can be reduced. That is, light
The size of the head 1 is 2mm high, 3mm wide and 6m long
m, the weight was 0.2 g, which was light. For this reason, linear
The movable coil 14B of the motor 14 and the suspension 15
The weight of the movable part including the movable part was reduced to 1.0 g or less. This result
As a result, the linear mode 14 alone has a bandwidth of 30 kHz or more and a gain of 6
0 or more was obtained. (C) The focal position shift due to temperature fluctuation is small. Sand
The main cause of defocus is temperature fluctuation.
In most cases, the laser beam is a parallel beam in most parts of the optical system.
In this portion, no defocus occurs due to thermal expansion. Impatience
The point that may cause the point shift is the semiconductor laser 19
To the collimating lens 4 and flint glass
This is a light collecting portion by the transparent light collecting medium 6. Flynn
The linear expansion coefficient of glass is 9 × 10^-6Less than or equal to light
In the operating temperature range (10 to 50 ° C.) of the disk device 10
The change in the length of the condensing portion is 0.4 μm at the maximum. Also,
Of the focal position
Is one order of magnitude smaller than the linear expansion, and the defocus caused by this is negligible.
Was. For the former collimating part, a collimating lens
4 and the collimating lens 4
The conductor laser 19 is fused with a fused silica plate having a low linear expansion coefficient (linear expansion coefficient).
Number is 5 × 10 ^-7) Connection by 21 and distance change between them
Was suppressed. The focal position shift due to this part is caused by temperature fluctuation 4
0.02 μm or less in a range of 0 degrees, and a depth of focus of 0.2
The range was sufficiently negligible for μm.

FIG. 9 shows tracking control characteristics. By the two-stage control by the linear motor 14 and the piezoelectric element 20, a band of 200 kHz is obtained as shown at 26 in the same figure, and 0.01 band under high-speed rotation (3600 rpm).
Tracking could be performed with an accuracy of μm. 27 is a response characteristic of the linear motor 14,
By performing the step control, a gain 28 of 80 dB or more was obtained. Also, an average seek speed of 10 ms or less was achieved for a 12 cm disk. Thereby, 3600r
The access time during pm rotation is less than 20 ms.

FIG. 10 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 30 used for the hard disk is used. The optical head 1 is connected to a rotary linear motor 30 by a suspension 31 rotatably supported by a rotary shaft 31. With such a configuration, the rotary linear motor 30 can be arranged outside the optical disk 12, so that the optical head 1 can be made thinner and the entire optical disk device 10 can be downsized. In addition, this allows the disk to operate at a high speed (3600 rpm).
m), enabling a data transfer rate of 50 Mbps or more on average. Also, in this device, the tracking direction is perpendicular to the light output direction of the semiconductor laser, so for tracking, the semiconductor laser or its output beam must be scanned in a direction perpendicular to the light output direction of the conductor laser. Needless to say, it does not have to be.

FIG. 11 shows an optical disk device according to the third embodiment of the present invention. This optical disk device has a first
Optical head 1 using transparent condensing medium 6 of the embodiment
Is applied to a five-stacked disk stack type optical disk device, in which five optical disks 40 having recording media 42, 42 attached to the upper and lower surfaces of a plastic substrate 41, respectively, and a recording medium for each optical disk 40 A suspension 44 that rotatably supports the optical head 1 by a rotating shaft 43;
Rotary linear motor 45 for driving suspension 44
And The recording medium 42 may be a phase change type medium or a magneto-optical type medium. Rotary linear motor 45
A movable piece 45a to which the suspension 44 is directly connected;
The electromagnets 45c, 45c are connected by a yoke 45b and drive the movable piece 45a. The structure of the optical head 1 is basically the same as that of the first embodiment, and uses a transparent condensing medium 6 having a paraboloid of revolution and an AlGalnN laser (410 nm). The diameter is 0.2 μm. Disk diameter is 12 cm, track pitch and mark length are 0.16 μm and 0.19 μm, respectively.
The capacity on one side is 60 GB, and the total capacity is 1.2 TB.

FIGS. 12A and 12B show a semiconductor laser according to the third embodiment. This semiconductor laser 46
Is a beam scanning type semiconductor laser having a substrate 460, an upper electrode 461 on the upper surface, and a lower electrode 46 on the lower surface.
2. An active layer 463 is formed at the center. The width of the main portion 464a and the tip portion 464b of the oscillation narrowing portion of the active layer 463 are 3 μm and 5 μm, respectively, and the lengths are 300 μm and 50 μm, respectively. Upper electrode 461
Are a main part electrode 461 a and a pair of left and right tip part electrodes 461.
b, 461b. The oscillation portion of the active layer 463 is narrowed by oscillation narrowing portions 464a and 464b, and the output light beam is scanned left and right by dividing the current into the tip electrodes 461b and 461b or by passing current alternately. This scanning width can be 1 μm and the scanning frequency can be up to 30 MHz. Tracking of two-stage control was performed by the laser beam scanning and the linear motor 45. The generation of the error signal for tracking control was performed by a laser beam wobbling method. That is, the laser beam is moved at a high speed (1
(0 MHz), the light spot on the recording surface is wobbled about 0.01 μm in proportion to the NA ratio of the collimator lens and the transparent light-collecting medium. As a result, the reflected signal from the recording track is modulated, and the modulated signal is detected in synchronization with the scanning frequency to generate an error signal.

According to the above configuration, high-speed tracking without a mechanically movable portion can be performed by scanning the laser beam right and left at high speed. Also, by using the rotary linear motor 45, the average seek time could be realized to be 10 ms or less as in the first embodiment. Further, the use of the transparent light-condensing medium 6 allows
A high-speed optical disk device with an ultra-large capacity of B or more has become possible.

The present invention is not limited to the above embodiment, but can be variously modified. For example, in the above-described embodiment, the sample servo method is used to generate the error signal for tracking control. However, the recording track is made to meander, and the modulation of the reflected light is synchronized with the meander frequency. A wobbled track method of detecting and generating an error signal may be used. Further, for example, when the beam power may be small as in the case of reproduction, the laser beam to be incident on the transparent light-collecting medium does not have to be collimated by the collimating lens. For tracking of a read-only disc, it is also possible to use a three-spot method as performed in a CD. That is, a diffraction grating is inserted between the collimator lens and the polarizing beam splitter, and photodetectors for detecting the reflected light of each of the ± primary lights from the disk are arranged on both sides of the main beam detecting element, and the output By taking the difference between the two, an error signal can be generated. 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. However, in this embodiment, since the semiconductor laser is scanned, the light spot of the photodetector moves right and left in accordance with the scanning. An erroneous signal due to this can be suppressed by scanning the photodetector right and left in synchronization with the scanning of the semiconductor laser. Further, the optical head of the present embodiment can be used for recording and reproducing on a write-once optical disc as it is. In addition, magneto-optical recording using a magneto-optical medium is also possible by mounting a thin-film coil around the light spot condensing part on the third surface (the lower surface of the flying slider) of the transparent condensing medium and performing magnetic field modulation. Becomes However, in the case of reproduction, in order to generate a signal by detecting the rotation of the polarization plane of light by polarization analysis, it is necessary to change the polarization beam splitter to a non-polarization splitter and place an analyzer in front of the photodetector. There is. Although an edge-emitting laser is used in this embodiment as a laser source, a surface-emitting laser (VCSEL) may 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 can be performed even with a surface-emitting type semiconductor laser. In the case of a surface-emitting type semiconductor laser, wavelength variation due to temperature is small, and chromatic aberration correction can be omitted. In this embodiment, a commercially available semiconductor laser having the shortest wavelength (630 nm) is used as the semiconductor laser, but an AlGalnN blue laser (410 nm) currently under development can be used in the same manner. In this case, the diameter of the light spot can be made 0.15 μm or less, and the density can be more than doubled.
In the present embodiment, a heavy-flint glass having a refractive index of 1.91 is used as the transparent light-collecting medium. However, if the refractive index is larger than 1, there is no upper limit, and a material having a higher refractive index is used. Can also. For example, a crystalline material such as cadmium sulfide CdS (refractive index 2.5) or zinc blende ZnS (refractive index 2.37) may be used. As a result, the diameter of the light spot can be further reduced by 20% or more, and the recording density can be increased by about 50%. As an optical recording medium, a read-only disk having uneven pits, a recording / reproducing medium using a magneto-optical recording material or a phase change material, and a write-once type in which uneven pits are formed by light absorption of a dye or the like for recording. Various recording media such as media can be used. When an edge emitting semiconductor laser is used as the semiconductor laser, the active layer may be arranged so as to be parallel to the third surface (the lower surface of the flying slider) of the transparent light-collecting medium.

[0055]

As described above, according to the present invention, the laser beam incident on the first surface of the transparent light-collecting medium is transmitted to the second surface.
Since a light spot is formed on the third surface by reflection on the surface, near-field light leaking from the light spot formed on the third surface to the outside of the third surface can be used for optical recording / light reproduction. Further, since the numerical aperture inside the transparent condensing medium can be increased, the light spot can be miniaturized. As a result, a high recording density becomes possible. In addition, since light can be collected without using an objective lens, the size of the optical head can be reduced, and the data transfer rate can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an optical head according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an optical head according to a second embodiment of the present invention.

FIG. 3 is a diagram showing an optical head according to a third embodiment of the present invention.

4A is a diagram showing an optical disc device according to the first embodiment of the present invention, and FIG. 4B is a cross-sectional view taken along line AA of FIG.

5 is a sectional view of an optical disk used in the optical disk device shown in FIG.

6A is a side view of an optical head used in the optical disk device shown in FIG. 4, and FIG. 6B is a plan view of the optical head.

FIG. 7 is a rear view of a flying slider used in the optical disk device shown in FIG. 4;

FIG. 8 is a diagram showing a semiconductor laser scanning unit used in the optical disk device shown in FIG.

9 is a diagram showing tracking control characteristics in the optical disc device shown in FIG.

FIG. 10 is a diagram illustrating an optical disc device according to a second embodiment of the present invention.

FIG. 11 is a diagram showing an optical disc device according to a third embodiment of the present invention.

12A is a plan view showing a semiconductor laser used in the optical disk device shown in FIG. 11, and FIG. 12B is a sectional view thereof.

FIG. 13 is a diagram showing a conventional first type optical head.

FIG. 14 is a diagram showing a second type of conventional optical head.

FIG. 15 is a diagram showing a conventional relationship between refractive index n and NA.

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

17 is a diagram showing the SIL and the flying slider of the optical disk device shown in FIG.

18 is a diagram illustrating a detection optical system unit of the optical disc device illustrated in FIG.

FIG. 19 is a view showing a conventional optical head.

FIG. 20 is a diagram showing another conventional optical disk device.

[Explanation of symbols]

 Reference Signs List 1 optical head 2 semiconductor laser 3 laser beam 4 collimator lens 5 parallel beam 6 transparent focusing medium 6a first surface 6b second surface 6c third surface 7 reflection film 8 recording medium 9 light spot 10 optical disk device 11 rotation axis 12 optical disk 12a Groove part 12b Land part 13 Tracking direction 14 Linear motor 14A Fixed part 14B Moving coil 15 Suspension 16 Optical head drive system 17 Signal processing system 18 Floating slider 18b Groove 19 Edge emitting semiconductor laser 20 Piezoelectric element 21 Fused silica plate 22 Polarized beam Splitter 23 1/4 wavelength plate 24 Photodetector 25 Head case 40 Optical disk 41 Plastic substrate 42 Recording medium 43 Rotating shaft 44 Suspension 45 Rotary linear motor 45a Movable piece 45b Yoke 45c Electromagnet 12 GeSbTe recording layer 122 Al reflective film layer 123 SiO2 layer 124 SiN layer 190 active layer 200 electrode terminal 201 electrode film 202 multilayer PZT thin film 460 substrate 461 upper electrode 461a main electrode 461b tip electrode 462 lower electrode 463 active layer 464a oscillation narrowing 464b Tip of oscillation constriction

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D118 AA01 AA13 BA01 BB06 BB07 BF02 BF03 CA11 CA13 EA11 5D119 AA01 AA11 AA22 BA01 BB04 BB05 CA06 DA01 DA05 EB02 FA05 FA18 FA22 JA06 JA57 JA64

Claims (36)

[Claims] A laser beam emitting unit for emitting a laser beam; a first surface on which the laser beam from the laser beam emitting unit is incident; a second surface for reflecting the laser beam incident on the first surface; And a third surface on which the laser light reflected by the second surface is condensed to form a light spot, and wherein a transparent light condensed to perform recording or reproduction with near-field light oozing from the third surface. An optical head, comprising: 2. The optical head according to claim 1, wherein said transparent light-collecting medium is provided with a reflector on said second surface. 3. The optical head according to claim 1, wherein the transparent light-collecting medium has a refractive index larger than 1. 4. The transparent light-condensing medium has a refractive index of n and a numerical aperture in the transparent light-condensing medium having NA of n · NA.
2. The optical head according to claim 1, wherein the optical head is set to 0.85 or more. 5. The optical head according to claim 1, wherein the first surface of the transparent light-collecting medium has a flat surface. 6. The optical head according to claim 1, wherein said third surface of said transparent light-collecting medium is a flat surface. 7. An optical head according to claim 1, wherein said second surface of said transparent light-collecting medium is constituted by a part of a paraboloid of revolution. 8. The optical head according to claim 1, wherein said second surface of said transparent light-collecting medium is constituted by a part of a spherical surface. 9. The reflection type medium, wherein the second surface of the transparent light-collecting medium is constituted by a part of a paraboloid of revolution, and the reflector is formed to constitute a part of a paraboloid of revolution. 3. The optical head according to claim 2, wherein the optical head is a hologram. 10. The structure according to claim 1, wherein said second surface of said transparent light-collecting medium is constituted by a part of a spherical surface, and said reflector is a reflection hologram formed so as to form a part of a spherical surface. Item 3. The optical head according to Item 2. 11. The optical head according to claim 2, wherein the second surface of the transparent light-collecting medium is formed of a flat surface, and the reflector is a reflection-type hologram formed in a flat shape. 12. The optical head according to claim 9, wherein said reflection hologram is constituted by a volume hologram. 13. An optical head according to claim 9, wherein said reflection hologram is constituted by an uneven binary hologram. 14. The transparent light-collecting media are in close contact with each other,
The first transparent medium and the second transparent medium having the same refractive index, the first transparent medium has the first surface and the second surface, The second transparent medium, 2. The optical head according to claim 1, further comprising a flying slider configured to fly and scan on the optical disk with the rotation of the optical disk, wherein the flying slider has the third surface. 15. An optical head according to claim 14, wherein said laser beam emitting means is arranged on said flying slider. 16. The optical head according to claim 1, wherein the transparent light-collecting medium has a structure in which a thin-film coil is provided around a position on the third surface where the light spot is formed. 17. An optical head according to claim 1, wherein said laser light emitting means includes a semiconductor laser for emitting said laser light. 18. An optical head according to claim 17, wherein said semiconductor laser is an edge emitting semiconductor laser. 19. The optical head according to claim 18, wherein said edge-emitting semiconductor laser has an active layer disposed so as to be perpendicular to said third surface of said transparent light-collecting medium. 20. The optical head according to claim 18, wherein said edge-emitting type semiconductor laser has an active layer arranged so as to be parallel to said third surface of said transparent light-collecting medium. 21. The optical head according to claim 17, wherein said semiconductor laser is a surface-emitting type semiconductor laser. 22. A laser light emitting means, comprising: a laser light source for emitting the laser light; and a laser light from the laser light source shaped into parallel light and incident on the first surface of the transparent condensing medium. The optical head according to claim 1, further comprising a collimating lens. 23. The optical head according to claim 22, wherein said second surface has a shape for reflecting said parallel light to form said light spot on said third surface. 24. The optical head according to claim 1, wherein the first surface and the third surface of the transparent light-collecting medium are each formed of a plane and are orthogonal to each other. 25. The laser light emitting means includes: a laser light source that emits the laser light; and a piezoelectric element that moves the laser light source to displace a position where the light spot is formed in a predetermined direction. The optical head according to claim 1 having a configuration. 26. The semiconductor laser according to claim 1, wherein the semiconductor laser is provided near a tip for emitting the laser light, and a current is divided or applied alternately to shift a position where the light spot is formed in a predetermined direction. 18. A beam scanning type semiconductor laser having a pair of electrode terminals to be displaced.
Optical head as described. 27. An optical disk device having a rotating optical disk and an optical head for recording or reproducing information by irradiating the optical disk with a laser beam, wherein the optical head comprises a laser beam emitting the laser beam. An emitting unit, a first surface on which the laser light from the laser light emitting unit is incident, a second surface for reflecting the laser light incident on the first surface, and the laser light reflected on the second surface. An optical disk, comprising: a third surface on which a light spot is formed by condensing light; and a transparent light condensing medium for performing recording or reproduction with near-field light oozing from the third surface. apparatus. 28. The optical disk apparatus according to claim 27, wherein said optical disk is a read-only medium on which information is recorded by an uneven pit array. 29. The optical disk device according to claim 27, wherein said optical disk is a magneto-optical recording medium. 30. The optical disk device according to claim 27, wherein said optical disk is a light phase change recording medium. 31. The optical disk apparatus according to claim 27, wherein said optical disk is a write-once recording medium that forms uneven bits by light absorption of a dye. 32. A plurality of rotating optical disks arranged coaxially at predetermined intervals, and a plurality of optical heads for irradiating a laser beam onto the plurality of optical disks to record or reproduce information. An optical head comprising: a laser beam emitting unit for emitting the laser beam; a first surface on which the laser beam from the laser beam emitting unit is incident; and the laser beam incident on the first surface. And a third surface on which the laser light reflected by the second surface is condensed to form the light spot, and is recorded by near-field light oozing from the third surface. An optical disc device comprising a transparent light-collecting medium for performing reproduction. 33. A rotating optical disc, and an optical disc apparatus for recording or reproducing information by irradiating the optical disc with a laser beam, comprising: a semiconductor laser for emitting the laser beam; A transparent condensing medium having a surface on which the incident laser light is condensed and a light spot of the laser light is formed, and by displacing an output position of the laser light from the semiconductor laser. A light spot displacing means for displacing a position where the light spot is formed with respect to the transparent light-collecting medium in a predetermined tracking direction; and an optical head provided with at least the semiconductor laser and the transparent light-collecting medium. An optical head moving means for moving the optical head in the predetermined tracking direction. Apparatus. 34. The optical disk according to claim 33, wherein said light spot displacement means is driven based on an error signal in a high frequency range, and said optical head moving means is driven based on an error signal in a low frequency range. apparatus. 35. The apparatus according to claim 33, wherein said light spot displacing means includes a piezoelectric element for moving said semiconductor laser.
An optical disk device as described in the above. 36. A semiconductor laser, comprising: a pair of electrode terminals provided near a tip from which the laser light is emitted to move an output position of the laser light by dividing or alternately applying a current. A beam scanning type semiconductor laser comprising: the light spot displacing means, wherein the light spot is formed by dividing or alternately applying a current to the pair of electrode terminals of the beam scanning type semiconductor laser. 34. The optical disc device according to claim 33, wherein a position is displaced in the predetermined tracking direction.