JPH0369032A - Optical head - Google Patents

Abstract

PURPOSE:To increase a recording density and to shorten access time by providing a two-dimensional condenser element which condenses the exit light from a light source on the optical path between the light source and an optical disk and forms a spot on the optical disk. CONSTITUTION:The optical disk device is constituted of the optical disk 50, the optical head 110 and an arm 60 to support the optical head 110. This head 110 is constituted of an air slider 40, a semiconductor laser, a photodetector 20, and a micro Fresnel lens 30. The head 110 is prevented from increasing its weight by using the lens 30 as the condenser element. The numerical aperture of the lens 30 is increased by decreasing the distance L1 between the disk 50 and the condenser element 30 of this constitution, by which the spot size is reduced and the recording density is increased. The construction is simplified and the access time is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical head for reading information from an information recording medium such as an optical disk, a method for accessing the information recording medium, and an optical disk device.

[Conventional technology]

Generally, the access time of an information recording medium such as an optical disk, which is a mass storage device, is determined by how fast an optical pickup can be moved by a linear motor, and the speed is controlled by the weight of the optical head. A floating optical head can reduce weight and access time by downsizing the optical head.

As a conventional floating optical head, 0 is shown in Fig. 2 (a) to (c).
ptica Q Data S toraga
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The optical head is attached to an air slider.

Floating close to the optical disc. To reproduce information recorded on an optical disk, as described in Japanese Patent Application Laid-Open No. 63-74128, a semiconductor laser is used as a light source, and the drive current of the semiconductor laser is set to below the oscillation threshold to make the laser non-oscillating. irradiate the optical disc with the emitted light,
The reflected light is returned to the semiconductor laser, and the optical output (composite resonance signal output) is received by a photodetector. As a result, it is possible to obtain a data signal corresponding to a change in reflectance of the optical disc (presence or absence of information bits).

However, conventional floating optical heads do not have a two-dimensional condensing optical element that focuses the light from the light source onto the optical disk, resulting in an elliptical spot and an inability to increase information recording density. Ta.

Regarding the actuation of the optical head in the radial direction, coarse actuation (response <several tens of Hz) involves moving the optical head along with the arm to access the desired track.
, stroke〉several mm), and fine movement actuation that non-mechanically moves the light beam minutely to follow a specified track (response〉several tens of KHz, stroke number +μ)
It is desirable to have two such optical heads, such as those described in Proceedings of the Optical Memory Symposium '88, pp.
There is one shown in 67. However, conventional floating optical heads do not have a high-speed fine-movement actuation mechanism, so they have poor track followability.

It has not been possible to increase track density and at the same time further reduce access time.

[Problem to be solved by the invention]

The conventional floating optical head described above does not have a two-dimensional condensing optical element, so it cannot condense the light beam into a diffraction-limited circular spot, and it does not have a mechanism for finely moving the light beam.

It was not possible to increase the density of recording tracks.

In view of the above-mentioned conventional problems, an object of the present invention is to provide a floating optical head that focuses a light beam to the diffraction limit and is provided with a fine movement actuation mechanism to increase recording density and shorten access time, and to provide a floating optical head equipped with the same. An object of the present invention is to provide an access method for an optical disc device and furthermore an optical information recording medium.

[Means to solve the problem]

In order to achieve the above object, the present invention installs a light source, which was conventionally close to an optical disk, away from the optical disk, and places an optical element with a two-dimensional light focusing function such as a micro Fresnel lens in between, so that the light source can be placed on the optical disk. obtain a diffraction-limited circular spot. At the same time, an optical deflector such as an AO modulator is installed between the light source and the optical disk as a fine actuation mechanism for the light beam, and by swinging the light beam at high speed in the radial direction of the disk using electrical signals, track tracking is improved. to increase track density and shorten access time.

That is, the optical head according to the present invention includes a light source that irradiates light onto an optical information recording medium, a photodetector that detects reflected light from the optical information recording medium, and the light source and the photodetector. an air slider that floats close to the optical information recording medium;

In the optical head, the light emitted from the light source is focused on the optical path of the air slider between the light source and the optical information recording medium to form a circular shape on the optical information recording medium. A two-dimensional condensing element is provided to connect the spots.

Further, the optical head according to the present invention includes a light source that irradiates light onto an optical information recording medium, and a photodetector that detects reflected light from the optical information recording medium.

an air slider that levitates the light source and the photodetector close to the optical information recording medium, the air slider having a space between the light source and the optical information recording medium; A two-dimensional condensing element is provided on the optical path of the light source and connects the light emitted from the light source to a circular spot on the optical information recording medium, and a two-dimensional condensing element is provided between the light source and the optical information recording medium. A light deflecting means for deflecting the spot in the radial direction of the optical information recording medium is provided on the optical path of the optical information recording medium.

In the optical head, the optical deflection means may include an optical nonlinear medium and an electrode for controlling the shape of the spatial distribution of refractive index within the optical nonlinear medium by an electro-optic effect or an acousto-optic effect. . Alternatively, the optical deflection means may include a multi-quantum well layer as a waveguide layer, and a first waveguide layer having a refractive index smaller than that of the multi-quantum well layer. A second semiconductor layer is used as a cladding layer and is provided vertically in contact with the multi-quantum well layer in the stacking direction, and a gate electrode, a source electrode, and a drain electrode are formed on the first semiconductor layer.

An example is a field effect transistor using the multi-quantum well layer as a channel.

The optical head preferably includes means for separating an optical path from the light source to the optical information recording medium and an optical path from the optical information recording medium to the photodetector. Further, the two-dimensional condensing element may be at least one diffractive lens.

Further, in the optical head, the light source is a semiconductor laser, and the semiconductor laser has at least two or more active layers and at least two or more electrodes parallel to the stacking direction of the active layers, and the two electrodes The light beam may be deflected by changing the magnitude of the current flowing through the light beam. Further, it is preferable that the light source is provided with a heat sink that keeps the temperature of the light emitting part constant, and the light source, the photodetector, the light deflection means, and the two-dimensional condensing element are integrally formed within the waveguide. There is also.

Furthermore, the method for accessing an optical information recording medium according to the present invention includes a step of condensing light emitted from a light source by a two-dimensional condensing element to form a circular spot on the optical information recording medium, and a step of optical deflection. The method includes accessing the spot to a desired data area by a means, and detecting reflected light from the desired data area by a photodetector.

Another aspect of the present invention is an optical disc device comprising an optical disc, a means for rotating the disc, an optical head for writing, erasing, or reproducing information on the optical disc, and a control means for the optical head. The optical head is any of the optical heads described above.

[Effect]

The two-dimensional condensing optical element in the above configuration is small and
A lightweight thin film lens such as a micro Fresnel lens is suitable. While general bulk lenses use refraction to condense light, micro Fresnel lenses use light diffraction and can be made into thin films. Theoretical handling of micro Fresnel lenses is explained in, for example, "Optical Integrated Circuits" by Hiroshi Nishihara.

As a non-mechanical means of light deflection, a spatial distribution of refractive index can be created within the waveguide to bend the guided light. The principle will be explained using FIGS. 3 and 4.

FIG. 3(a) shows a case in which light propagates within a waveguide having a −-like refractive index. In the figure, 100 is a light beam, 400 is a waveguide, and 410 and 420 are electrodes. Since no potential difference is provided between the two electrodes, the refractive index within the waveguide 410 has a −-like distribution.

At this time, the light beam 100 travels straight. On the other hand, Fig. 3 (b
) is the case where a potential difference is created between the electrodes 420 and 430, and a refractive index gradient is created between the two electrodes due to the electro-optic effect, and the light beam 100 is bent toward the side with a larger refractive index.

FIG. 4 shows the calculation results of the propagation process of a diffused beam incident on a waveguide having a --like refractive index gradient. The propagation direction of light in the two-dimensional waveguide is taken as two axes, and the lateral direction of the waveguide perpendicular to the Z-axis is taken as the X-axis. The wavelength of the light is 0.83 μm. As shown in FIG. 4(b), the waveguide lateral refractive index distribution has an isolateral refractive index of N=3.5 at 2=0 to 50 μm.
Constant, N = 3.5 to 2250 to 400 μm
Assume a linear distribution of 3.6. The optical beam propagation phenomenon at this time was analyzed. The curve in FIG. 4(a) is the propagation path 115.
From this figure, which shows the amplitude distribution of light every 0 μm, Z = 50
It can be seen that the light beam is gradually deflected to the right side where the refractive index is higher than the micrometer. At Z=400 μm, the amplitude peak position is shifted to the right by 13.5 μm, and the amount of deflection can be controlled by the amount of change in the refractive index.

By using such an optical deflector, it becomes possible to move the focused spot of the light beam in the radial direction of the optical disk at high speed.

In addition, examples of optical deflectors other than those described here include, for example, LiNb0. A Ti diffusion waveguide and a comb-shaped electrode are formed on a substrate. When a high-frequency alternating current voltage is applied to the comb-shaped electrodes to generate surface acoustic waves in the waveguide, the traveling direction of light can be changed by the acousto-optic effect. This type of optical deflector can also be used in an optical head.

〔Example〕

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

FIG. 1 is a schematic configuration diagram showing an optical system according to an embodiment of the present invention. In the figure, 10 is a semiconductor laser which is a light source, 20
30 is a photodetector, 30 is a micro Fresnel lens as a two-dimensional condensing element, 40 is an air slider, 50 is an optical disk, 60 is an arm, 100 is a light beam, and 110 is an optical head. As shown in FIGS. (a) and (b), an optical disk 50, an optical head 110
, and an arm 60 that supports an optical head.

This optical head is composed of an air slider 40, a semiconductor laser 10, a photodetector 20, and a micro Fresnel lens 30, as shown in FIG. 1(C). By using a micro Fresnel lens as a condensing element, the weight of the optical head is prevented. air slider 40
floats close to the optical disk 50, and its flying height is determined by the rotational speed of the optical disk 50 and the shape of the air slider 40, and can be set in a range of about 0.2 to 5 μm.

Next, the signal reproducing operation of the optical head of the present invention will be explained. The driving current of the semiconductor laser 10, which is a light source, is set below the oscillation threshold value, and the optical disc 50 is irradiated with emitted light in the laser non-oscillation state. The reflected light is returned to the semiconductor laser 10 and the optical output (composite resonance signal output) is received by the photodetector 20. As a result, a change in the reflectance of the optical disc 50 (
A data signal corresponding to the presence or absence of information bits can be obtained. In order to improve the signal reproduction performance of the optical head of the present invention, an anti-reflection coating (Anti-Reflection Coating) is applied to the output surface of the 50 optical disks of the light source 10.
ng). As a result, the light source 10
The coupling between the optical disc 50 and the optical disc 50 is strengthened, and the signal reproduction sensitivity is increased.

Regarding the positional relationship among the light source 10, the condensing element 30, and the optical disk 50, it is preferable that the spot diameter on the optical disk is smaller because the recording density of information becomes higher. optical disc 5
0 and the optical element 30, and the distance between the condensing element 30 and the light source 10 is L2, the following relationship holds when the diameter of the condensing element 30 is constant.

(1) When L is made smaller, the numerical aperture of the lens becomes larger and the spot size can be made smaller.

(2) Reducing LX increases the efficiency of using the light emitted from the light source.

FIG. 5 shows a configuration diagram of an optical head using a thin film lens whose focal position changes little with respect to wavelength fluctuations of a light source. In the figure, 10 is a light source, 20 is a photodetector, 30 is a screen grating lens, 31 and 32 are two grating surfaces of the double-sided grating lens 30, 40 is an air slider, and 50 is an optical disk. A grating lens that uses light diffraction has larger chromatic aberration than a bulk lens that uses light refraction, so if the wavelength of the light source deviates from the designed value, it will not be possible to focus the light beam to the diffraction limit. However, as shown in the Proceedings of the Optical Memory Symposium '88, Pp33, a condensing optical system with small chromatic aberration can be constructed by combining two grating surfaces. Therefore, in the present invention, this technology is applied to a floating optical head.

The characteristics of the double-sided grating lens 30 shown in FIG. 5 will be explained below. After the light beam of wavelength λ1 that is emitted from the light source 10 and enters the outermost radius R of the grating surface 31 is diffracted, it reaches the center r□ of the grating surface 32, and is further diffracted and proceeds along the optical axis. Like, R Engineering, r
The grating pitch PtyPt in □ can be determined. It is assumed that the spot is a point P on the optical disk, and the wavelength changes from λ to λ2 (λ2>λ,).

Due to the longer wavelength, the light beam diffracted by R8 reaches a point r2 on the grating surface 32, which is different from rl (
wavy line). A pitch P2 of r2 is calculated so that the beam is focused on the spot P even if the wavelength changes.

The wavelength is returned to λ again, and the emission point R2 on the grating surface 31 of the light beam diffracted toward P at r2 is determined. R
Since the light beam diffracted at point 2 comes from point O, the pitch P2 of R2 can be found. By repeating the above process n times, the pitch distribution of the two gratings can be determined. Here, the value of rn represents the radius of the grating.

When the trajectory of the light ray described above is rotated around the optical axis, it is axially symmetrical and has two wavelengths λ4. A grating lens with no aberration for λ2 is realized.

FIGS. 6(a) and 6(b) show an embodiment in which an optical deflector is used as the tracking means. In the figure, 10 is a light source;
20 is a photodetector, and 30 is a condensing element.

40 is an air slider, 50 is an optical disk, 60 is an arm, and 70 is an optical deflector. By providing the optical deflector 70 on the optical axis between the light source 10 and the lens 30, the light beam from the light source 10 can be changed by a desired angle and irradiated onto the lens 30. Thereby, it is possible to scan the optical disk 50 while focusing the light in the tracking direction.

FIG. 7 shows the configuration of an acousto-optic element suitable for the optical deflector of the optical head of the present invention. In the figure, 73 is an electrode, 74 is
75 represents an acoustic absorber, and 101 and 102 represent light beams, respectively. The high frequency signal applied to the electrode 73 generates an elastic wave within the acousto-optic crystal 74 having a piezo effect.

Since the elastic wave is a longitudinal wave, that is, a density wave, a refractive index distribution occurs in the acousto-optic crystal 74 corresponding to the density. If the high frequency signal is a sine wave, the refractive index distribution will also be sinusoidal, and a refractive index distribution type grating will exist within the crystal. When a light beam 101 enters the acousto-optic crystal 74 in this state with an inclination of θ with respect to the normal to the entrance surface, it is diffracted, and becomes a light beam 102 with an inclination of θ2 with respect to the normal to the exit surface. It emits light. Here, the frequency of the high-frequency signal applied to the electrode is f, and the velocity of the elastic wave in the crystal is vs
, the wavelength is A, and the wavelength of light is λ, then the following formula is established.

Here, if the change in the frequency of the high frequency signal is δf, the pitch of the gradient index grating produced in the crystal changes as the high frequency changes, and the diffraction surface changes. Now, δ
Assuming that the change in the diffraction surface due to f is δθ2, the following equation holds true.

That is, from the above explanation, it is understood that the beam can be deflected by changing the frequency of the applied high frequency.

FIG. 8 is a sectional view of an optical deflector using a multiple quantum well suitable for the floating optical head of the present invention. 400 in the same
is a waveguide layer using GaAs/AQGaAs multiple quantum well, and 401 and 402 are AQGaAs.
403 is a GaAs bathophore layer, 404 is a semi-insulating GaAs substrate, 406 is an impurity diffusion region, 410 is a source electrode, 420 is a drain electrode, 4
Reference numerals 30 and 30 respectively indicate gate electrodes.
Waveguide N40o using a A s / A Q G a A s multiple quantum well is a GaAs well layer and A n G
It is formed by alternately stacking a A s layers. 410,4
Each electrode 20 and 430 is made of A u G by vacuum evaporation method.
E is attached and Au is laminated thereon. The impurity diffusion region 406 is connected to the source electrode 410 and the drain electrode 42.
This is an n-type diffusion region obtained by heat treatment after forming 0.

Next, the operation of this optical deflector will be described. The gate voltage v2 is O, and the source electrode 410 and the drain electrode 420
When the potentials are made equal, the entire multi-quantum well layer has a uniform electron distribution, the refractive index distribution is also uniform, and light travels straight through the waveguide layer 400. When the gate voltage Vg is set to a negative potential and a potential difference is created between the source electrode 410 and the drain electrode 420, electron distribution is created within the multiple quantum well layer. Since the electron density is large and the refractive index is also large, for example, if the source electrode 41O is at a lower potential than the drain electrode 420, light will propagate within the waveguide layer 400 without being bent toward the source electrode 410 side.

Figure 9 is Applied Physics Letter 33 (1
978) page 702 (AppQ, Phys, Let
This is a twin-stripe semiconductor laser having a beam deflection function as described in J. T., 33 (1978) PP702). The semiconductor laser in FIG. 9(a) is n-G
There are two active layers and two electrodes, and the beam can be deflected by changing the magnitude of the current flowing through the two electrodes. FIG. 9(b) shows the light emission characteristics of a twin-stripe semiconductor laser.
The radiation angle θ of the light beam can be changed by changing the ratio of the magnitudes of . If this twin-stripe semiconductor laser is used as a light source for the floating optical head of the present invention, there is no need to use a beam deflector, and the number of parts can be reduced and the configuration of the optical head can be simplified.

FIG. 10 is a configuration diagram of a floating optical head in which a heat sink is added to a light source. In the figure, 10 is a light source.

20 is a photodetector, 30 is a lens, 40 is an air slider, 50 is an optical disk, 60 is an arm, and 80 is a heat sink. The heat sink may be a metal with high thermal conductivity, a radiation fin, or a combination of a temperature sensor such as a thermistor and an element that absorbs and absorbs heat, such as a Peltier element. When a semiconductor laser is used as the light source 10.

During oscillation, the oscillation wavelength changes as the band gap and resonator length change due to temperature changes.

Therefore, by providing a heat sink as shown in FIG. 10, it becomes possible to keep the temperature of the semiconductor laser constant and keep the oscillation wavelength constant. Therefore, even if a grating lens with large chromatic aberration is present in the optical system, it is possible to prevent deterioration of light collection characteristics.

FIG. 11(a) shows an example in which the above optical elements are integrally integrated on a waveguide substrate, and FIG. 11(b) shows an example of the configuration as a floating optical head. In the figure, 40 is an air slider, 50 is an optical disk, 10O is a light beam, 200 is a waveguide type optical head, 201 is a two-dimensional waveguide, 220 is a grating coupler, and 230 and 231 are waveguide type photodetectors. 240 represents a light source formed in a waveguide, and 250 represents a waveguide type optical deflector. Two-dimensional waveguide 201
The light source 240 is configured so that the emitted light is coupled therein, and the emitted light beam 100 is made incident on the waveguide type optical deflector 250 via the two-dimensional waveguide 201 to control the propagation direction of the guided light. The subsequent light flux 100 also passes through the two-dimensional waveguide 2
01 and incident on a grating coupler 220 formed on the waveguide. The grating coupler 220 converts the waveguide mode into a radiation mode out of the waveguide, and focuses the light onto the optical disk.

The reflected light from the optical disk is then returned to the grating coupler 220, which in turn focuses the light onto the waveguide type photodetectors 230, 231.

The waveguide type optical head 200 integrated as described above is adhered to the air slider 40 as shown in FIG. 11(b), and the emitted light from the grating coupler 220 is focused on the optical disk 50.

Next, a first embodiment regarding the signal detection method is shown in FIG. 12, in which 10 is a light source, 21 and 22 are photodetectors, and 30
40 is a lens, 40 is an air slider, 51 is a track groove of the optical disk, 52 is a tracking direction, 70 is an optical deflector, and Zoo, 101, and 102 are light beams, respectively. The 3° lens has two functions: a light condensing function and a beam splitter, by using overlapping grating patterns or double-sided grating technology. The light beam 100 whose propagation direction is controlled by the optical deflector 70 is directed to the track 1l1 by the focusing function of the lens 30.
The light is focused on 51. The reflected light returns to the incident optical path, and is split into light beams 101 and 102 by the beam splitter function at the lens 30, which are detected by the photodetector 2.
1.22 and read out as an electrical signal. 2
A reproduced signal is obtained from the sum of the outputs of the two photodetectors 21 and 22, and a tracking error is obtained from the difference between them.

A second example of the signal detection method is shown in FIG. 13(a).

Shown in (b). In the figure, 10 is a light source, 20 is a photodetector, 3
0 is a lens, 40 is an air slider, 50 is an optical disk, 5.1 is a track groove, 52 is a tracking direction, 70
is a light deflector, and 100 and 101 are light beams, respectively. A light beam 100 whose propagation direction is controlled by an optical deflector 70
is removed from the optical axis by the lens 30 and focused on the track groove 51 on the optical disc 50. Since the optical axis is off, the reflected light beam 101 reaches the photodetector 20 without returning along the incident optical path. At this time, the diffracted light 102 by the track groove 51 is emitted to both sides of the tracking direction 52 across the track groove 51 (FIG. 13(b)), and is received by the photodetector 20, which is divided into two. By doing so, the read signal and tracking signal are detected.

FIG. 14 is a schematic diagram of an optical disk device to which the floating optical head of the present invention is applied. In FIG. 14, 50 is an optical disk, 300 is an optical head, 310 is a spindle motor, and 320 is a control circuit. optical disc 50
is rotated by a spindle motor 310, and the optical head 300 flies close to the optical disk 50. The optical head 300 can move radially on the optical disk 5o to access a predetermined track. The control circuit 320 functions to send command signals to the optical deflector in the optical head for signal encoding, laser intensity modulation, and tracking control in order to record, reproduce, and erase signals on the optical disk. . This makes it possible to realize an optical disc device with high recording density and short access time.

〔Effect of the invention〕

According to the present invention, since a two-dimensional condensing element is provided, a light beam can be condensed to a diffraction-limited circular spot, and recording density can be increased. Furthermore, since the position of the light source on the slider is not at the lower end of the slider, there is less risk of the light source itself being destroyed even if the slider comes into contact with the disk when the disk rotation stalls.

Furthermore, since the optical deflection means is provided, it is sufficient to simply wave the beam, thus making it possible to shorten the access time.

Further, according to the access method according to the present invention, the structure can be simplified and the access time can be shortened.

According to the present invention, it is possible to realize an optical disc device that increases the recording density of information and shortens the access time.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an optical system according to an embodiment of the present invention, in which FIG. 1(a) is a side view of the main part, FIG. 1(b) is a plan view of the main part, and FIG. 2 is an enlarged side view, FIG. 2 is a configuration diagram of a conventional floating optical head, and FIG. 2(a) is a perspective view.
Figure (b) is an enlarged side view of the main part, Figure (c) is Figure (b).
Figure 3 is a diagram of the operating principle of a waveguide-type optical deflector that utilizes refractive index distribution, with (a) showing the case where there is no potential difference, and (b) showing the case where there is a potential difference. In this case, FIG. 4 is the result of calculating the propagation process of a diffused beam incident on a waveguide having a --like refractive index gradient. The figure (a) shows the amplitude distribution of light for each propagation distance, the figure (b) shows the refractive index distribution, and Figure 5 shows the light using a thin film lens whose focal position changes little with respect to the wavelength change of the light source. 6(a) and 6(b) are a side view and a plan view of an optical head using an optical deflector as a tracking means, and FIG. 7 is a diagram showing an optical head suitable for the optical deflector of the optical head of the present invention. A schematic configuration diagram of an acousto-optic element. FIG. 8 is a cross-sectional view of an optical deflector with a multiple quantum well structure suitable for the floating optical head of the present invention, FIG. 9(a) is a perspective view of a twin-stripe semiconductor laser having a beam deflection function, and FIG. (b) is a diagram showing its light radiation characteristics, Figure 10 is a configuration diagram of a floating optical head with a heat sink added to the light source, and Figure 11 (a) is a diagram showing each optical element integrated on a waveguide substrate. FIG. 11(b) is a schematic configuration diagram showing an embodiment of the optical head; FIG. 11(b) is a side view of the main part of the optical head attached to a slider; FIG. 12 is a plan view showing the first embodiment regarding the signal detection method; FIG. 13(a) is a plan view showing a second embodiment of the signal detection method, FIG. 13(b) is an enlarged view of the main part of FIG. 13(a), and FIG. 14 shows the floating optical head of the present invention. 2A and 2B each show a schematic perspective view of an optical disc device to which the application is applied. 10... Light source, 20... Photodetector, 30... Lens. 40... Air slider, 50... Optical disc, 6
0...Arm, 70...Light deflector, 100...Light beam. ga 1 figure (0)

Claims (1)

[Claims] 1. A light source that irradiates light onto an optical information recording medium;
An optical head comprising: a photodetector that detects reflected light from the optical information recording medium; and an air slider that floats the light source and the photodetector close to above the optical information recording medium, A two-dimensional condenser is provided on the optical path of the air slider between the light source and the optical information recording medium to condense the light emitted from the light source to form a circular spot on the optical information recording medium. An optical head characterized by being provided with an optical element. 2. a light source that irradiates light onto an optical information recording medium;
An optical head comprising: a photodetector that detects reflected light from the optical information recording medium; and an air slider that floats the light source and the photodetector close to above the optical information recording medium, A two-dimensional condenser is provided on the optical path of the air slider between the light source and the optical information recording medium to condense the light emitted from the light source to form a circular spot on the optical information recording medium. An optical head comprising: an optical element; and a light deflecting means for deflecting the spot in a radial direction of the optical information recording medium on an optical path between the light source and the optical information recording medium. 3. In claim 2, the optical deflection means uses a multiple quantum well layer as a waveguide layer, and uses first and second semiconductor layers having a smaller refractive index than the multiple quantum well layer as cladding layers, respectively. Provided vertically in contact with the stacking direction of the well layer,
An optical head that is a field effect transistor in which a gate electrode, a source electrode, and a drain electrode are formed on the first semiconductor layer, and the multi-quantum well layer is used as a channel. 4. The optical head according to claim 1 or 2, comprising means for separating an optical path from the light source to the optical information recording medium and an optical path from the optical information recording medium to the photodetector. 5. The optical head according to claim 1 or 2, wherein the two-dimensional condensing element is at least one diffractive lens. 6. In claim 1, the light source is a semiconductor laser, and the semiconductor laser has at least two or more active layers and at least two or more electrodes parallel to the stacking direction of the active layers, An optical head that can deflect a light beam by changing the magnitude of the current flowing through the electrodes. 7. The optical head according to claim 1, wherein the light source is provided with a heat sink for keeping the temperature of the light emitting part constant. 8. The optical head according to any one of claims 1 to 6, wherein the light source, photodetector, optical deflection means, and two-dimensional condensing element are integrally formed within a waveguide. 9. A step of condensing the light emitted from the light source by a two-dimensional condensing element to form a circular spot on the optical information recording medium, and a step of accessing the spot to a desired data area by a light deflecting means. , detecting reflected light from the desired data area with a photodetector. 10. An optical disc apparatus comprising an optical disc, a means for rotating the disc, an optical head for writing, erasing, or reproducing information on the optical disc, and a control means for the optical head, wherein the optical head is according to claims 1 to 9. An optical disc device characterized by being an optical head according to any one of the following.