JPH03214433A - Optical head - Google Patents

Abstract

PURPOSE:To increase an access speed and to improve condensing performance and return light detecting function by connecting any of optical elements which convert the light from a light source to divergent light or convergent light to the moving part of an actuator. CONSTITUTION:An optical deflector 40 is provided on a waveguide 20 and the divergent guided light 21 is deflected within the plane of the waveguide to allow tracking on an optical disk 2. The guided light 21 is made incident on a grating element 22 and is wavefront converted to the divergent light 26 to generate the convergent light 36 by an objective lens 24. This light is con densed to the optical disk 2. The light reading the information of the disk 2 is advanced backward and is detected by a photodetector through the element 22. The optical waveguide 20 is disposed to face via the air 10 and electrodes 12, 14 are provided on the opposite surface. A voltage is impressed to the electrodes from a power source and a controller 16. Electrostatic force is generat ed between the electrodes 12 and 14 and a focus displacement is generated in the waveguide 20 if the force overcomes the rigidity of a cantilever 34. The focus control by the voltage value is, thereupon, possible and the condensing performance and the return inspection performance are improved.

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, and particularly relates to an optical head suitable for reducing the weight of the optical head and increasing the access speed. This invention relates to a drive means for a pickup.

[Conventional technology]

The access time to information recording media such as optical disks, which are large-capacity storage devices, is from 1 μm to several tens of μm for optical pickups.
The decision is made based on how fast fine tracking can be achieved, moving up to a distance of several tens of micrometers, and ranking to course 1, which is a shift from several tens of micrometers to several tens of micrometers. The speed of course tracking is controlled by the weight of the optical head.

A conventional example of integrating optical components constituting an optical head on a single substrate to achieve significant weight reduction is the journal of the Institute of Electronics and Communication Engineers (C), J69-C, 5, pp609-615.
('86/5). The integrated optical head
Shown in Figure 0.

In the figure, light end-coupled from a light source 6 to a two-dimensional optical waveguide 20 propagates while spreading within the waveguide 20, and is converted into a spherical wave that is focused onto an optical disk 2 by a focusing grating coupler (FGC) 120. . The light from the optical disk 2 travels backward, is split into two parts by a beam splitter 122, and is focused on each of the photodetectors 8 in an array. When calculation is performed between the output electrical signals of the four photodetectors 8, "four raw signals, a focus error signal, and a tracking error signal are obtained simultaneously.

On the other hand, FIG. 11 is a diagram showing a schematic configuration of a conventional example of an optical head used in an optical disc device such as a compact disc player.

In the figure, a light beam l2 emitted from an f-8 body laser 68 as polarized light (1) is made into a parallel beam by a collimator I lens 70, and then sent to a polarizing beam splitter (+' II S ).
72 and is converted into circularly polarized light by a 1/4 wavelength plate 74, it is condensed by an objective lens 76 to a diameter of approximately 1 μm by an original disk 78], and is condensed into a condenser 80 by a condensing pointer 1. be done. The reflected light from the optical disk 78 is made into parallel light by the objective lens 76, passes through the I/4 wavelength plate 74, is converted into S-polarized light, is reflected by I) II S72, and is converted into light by the detection lens 82. The light is focused on a detector 84. In this way, the information recorded on the optical disc 78 can be read.

At this time, the focus error and tracking error of the focused spot 80 can be extracted by the photodetector 84 using the Foucault method, push-pull timing, or the like.

The detection circuit 86 takes in the signal from the photodetector 84 and calculates the focus error and tracking error. This calculation result is output to the clearance circuit 88, and the drive device 126
objective lens 76 to control and correct the error.
move. The tilting device 126 consists of a coil 128 that moves the objective lens 76 and a permanent magnet 130 that creates a magnetic field. When a focus error occurs, the objective lens 7G is moved along the optical axis direction so that the focus error disappears, and when a tracking error occurs, the objective lens 7G is moved along the optical axis direction.
6 is moved in a direction perpendicular to the optical axis so that the 1 to rank error is eliminated.

[Problem to be solved by the invention]

The integrated optical belly button 1 shown in FIG. 10 does not have any actuator mechanism for focusing and tracking, so for example, for fine access, a very heavy two-dimensional actuator consisting of a conventional permanent magnet and a voice coil is used. I had to. Course access becomes somewhat faster as the optical system becomes more integrated and lighter, but as long as two-dimensional actuators are used, no significant improvement can be expected. This is because if permanent magnets and the like are made smaller in order to reduce weight, the electromagnetic force will be weakened, creating a new factor that will reduce access speed.

Furthermore, FGCl20, which is the main optical system of this prior art,
Because the shape of the grid cannot be expressed by a simple equation such as a straight line or a circle, some kind of approximation is usually made when producing the grid. For example, in the conventional example 12, when manufacturing by analog scanning using an electron beam drawing device, the shape of the FGC 120 is approximated by a polygonal line. In this way, in the production of I"GC120, principle production errors are usually unavoidable, and the produced FGC1
20 had large aberrations, and it was extremely difficult to focus the light beam to the diffraction limit.

In addition, FGC120 has strong incident angle selectivity, and even if the incident angle of the returned light changes by, for example, 0.1 degree, no light will enter the waveguide at all, making it impossible to stably detect the light. there were.

On the other hand, in the conventional example shown in FIG.
30 and a coil 128 that moves within the static magnetic field to move the objective lens 76, the moving device 126 becomes large and the optical head becomes heavy as a result, so it is necessary to move the entire optical head with a linear motor. There was a major problem in that the speed of coarse actuation performed by movement decreased.

A first object of the present invention is to provide an optical head that has a fast access speed and excellent light collection performance and return light detection function.

A second object of the present invention is to provide an optical head that is lightweight and has a high access speed without using permanent magnets, coils, or the like.

[Means to solve the problem]

In order to achieve the first object, the present invention uses an electric optical deflector that utilizes an electro-optic effect in a waveguide medium as a tracking means. In addition, instead of the FGC, an arc-shaped grating coupler, which is easy to manufacture, is used, and the light deflected by the deflector is emitted outside the waveguide as diverging light, and the light is condensed by an external lens. . As the focusing means, an electrostatic actuator was used to move the entire optical waveguide. The detection optical system has a configuration in which the light transmitted through the grating covert is received by a six-divided photodiode.

In order to achieve the above-mentioned second object, the present invention sandwiches a dielectric material between two electrodes and uses electrostatic force generated by applying a voltage between the two electrodes to connect one electrode to the other electrode. An electrostatic microactuator that is moved relative to the object was used as a means of fine-tune access. Furthermore, in order to speed up access, we adopted an air slider system used in magnetic disk drives, and incorporated the micro actuator into a part of the air slider to further reduce weight.

[Effect]

By using an electric optical deflector for fine tracking, it is faster and lighter than conventional mechanical systems, making course access faster. By employing a grating coupler with a strong circular shape, it is possible to improve the processing accuracy compared to a complicated curve. In addition, this element only generates diverging light and does not focus it, so
There is no need to enlarge the aperture of the grating coupler, and the waveguide becomes very short and compact. Therefore,
The entire waveguide can now be moved by an electrostatic actuator, and since the light emitted from the waveguide is diverging light, it can be used as a focusing means by moving it in the focusing direction.

In addition, since the zero-order light that passes through the grating coupler adopted as the detection light always exists regardless of the fluctuation of the incident angle, the signal light can be detected stably.6 To achieve the second object of the present invention The principle of the adopted electrostatic microactuator is explained using Figure 6.
A cantilever 98 having, for example, a battledore-shaped cross section is formed by silicon micromachining, and the cantilever 98 is sandwiched from both sides by glass substrates 94 and 96 having thin film electrodes 90 and 92 formed on their inner surfaces. Cantilever 9
8 is a movable electrode, glass substrate-1 second electrodes 90, 92
Assuming that F is a fixed electrode, when a voltage ■ is applied between these electrodes, an electrostatic force F' expressed by the following equation is generated.

1"'=tSV"/2d" Here, E is the permittivity of the air gap, S is the area of the electrode, (1 is the distance between the fixed electrode and the 1'iJ rib electrode. This electrostatic force causes the fixed The cantilever can be displaced relative to the electrode by .chi.1, making it possible to configure an actuator in the focus, /J, or tracking direction.

〔Example〕

Next, an embodiment for achieving the first object of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a diagram showing the overall structure of a first embodiment of the optical head according to the present invention, and FIG. 1(a) is an L-side view of the optical head, (
b) is a front view, (c) is a view of the photodetector from below, (d)
) is a top view of a two-dimensional optical waveguide. In FIG. 1, 2 is an optical disk, 4 is an optical head, 6 is a light source using a semiconductor laser, 8 is a photodetector, 10 is air as a dielectric, 12.14 is an electrode, 16 is a power supply and control device,
18 is an electrostatic actuator, 20 is a two-dimensional optical waveguide,
21 is a diverging guided wave, 22 is an arcuate grating element, 23 is a diverging guided wave, and 24 is an objective lens. 26 is a light emitting device, 28 is a lens mount, and 30 is a photodetector substrate (Si).
, 32 is a cantilever substrate (Sj), 34 is a cantilever, 36 and 38 are convergent lights, and 40 is an optical deflector.

(d) As shown in the figure, the light emitted from the semiconductor laser 2 is
It is end face coupled to a two-dimensional optical waveguide 20 to form a diverging guided wave 22. Since an optical deflector 40 is provided on the waveguide 20, the diverging guided light 22 is deflected within the waveguide plane,
Tracking on the optical disc 1 is enabled. The deflection-controlled diverging waveguide light 22 enters the arc-shaped grating element, is wavefront-converted into the diverging light 26 shown in FIG.
Convergent light 36 is generated and focused on the optical disc 2. The light that has read the information on the second surface of the optical disk travels in the opposite direction and passes through the grating element 22 as zero-order light, as shown in Figure (b).
The signal enters the photodetector 8 shown in FIG. 8 and is simultaneously detected as a reproduction signal, a focus error signal, and a tracking error signal. Based on these signals, tracking control is performed by the optical deflector. Focusing control is performed with the following configuration. The 81 substrate 32 is removed by micromachining, leaving the cantilever 34 behind. The optical waveguide 20 is fixed to the tip of the cantilever 34, and the waveguide surface is opposed to the photodetector 8 provided on the upper substrate with the air 10 in between. At this time, on the opposing surface, as shown in FIGS. (b) and (c), electrodes 12.1
4 are provided, and a voltage is applied from a power source and control device 71 1 6. This voltage generates an electrostatic force between the electrodes, which overcomes the rigidity of the cantilever 34 and causes displacement of the waveguide 20 in the focus direction. If this amount of displacement is controlled by the voltage value applied between the electrodes 12 and 1.4, focusing control becomes possible.

The focus movement in case 2 is shown in FIG. 2(a).

When the optical waveguide 20 is displaced and comes to the position 20a, the diverging light 26 changes to the position 26a, and the converging light 3 by the objective lens 24
6 changes to 36a, and the optical disc 2 is brought into focus while moving to 2a.

In Figures 1 and 2 (a), an arc-shaped grating element is used, and the grating pitch is varied from dense to coarse in the direction of light transmission, producing diverging light.
Conversely, an embodiment using the FCC 23 shown in the prior art is shown in FIG. 2(b). As already mentioned, F G
In C 2 3, a convergent light that converges on a certain point is generated, and if it is emitted as it is, it will change to a diverging light 26, so
The rest is the same optical system as in Figure 2(a), with the same functions.

FIG. 3 shows an example of an actual journey of the optical deflector 40. The figure (.) shows the change in optical path due to optical deflection. Waveguide 2
When deflected by the optical deflector 40 on 0, the diverging waveguide light 21 changes to 21 (word), and the divergent light 26 exits the waveguide.
changes to 26c, and the convergent light 36 by the lens 24 becomes 36c.
Since it changes to c, tracking becomes possible. Same figure (
b) is a detailed view of the optical deflector 40. The waveguide 20 is T
It is i-diffused LiNbO', and 53 indicates its crystal axis direction. The electrode configuration includes an electrode 44 having almost the same shape as the optical path shape of the divergent waveguide light 21, and two electrodes 46.4 on both sides of the electrode 44.
It has 3 electrodes with 8. As shown in the figure, for example, the power supply 50 connects the electrodes 44 and 48 to O■, and the electrode 46 to +A.
When V is applied, the Z-direction electric field component in the waveguide changes, and an electric field gradient occurs within the optical cross section. For this reason,
When the polarization mode of the propagating light is the TE mode as shown in 56, for example, a refractive index gradient as shown in 52 occurs in the cross section 54, and the guided light 21 is deflected as shown in 21c. By reversing the polarity of the power source 50, the direction of deflection is reversed, and by changing the applied voltage, the amount of deflection can be controlled. FIG. 2C shows the result of analyzing the optical deflection phenomenon, and it can be seen that the optical wavefront 58 is deflected while expanding without being disturbed.

Note that 60 indicates the center line, and 62 indicates the optical amplitude peak position.

An embodiment of the focusing error and tracking error detection optical system is shown in FIGS. 4(a) and 4(b). First, the photodetector 8 is divided into three parts (8a, 8
b, 8c). Divided into two in the direction perpendicular to the track direction (8
d, 8e) Keep it.

In the case of focus error detection in (a), the focus state (
The photodetector 8 is arranged so that the divergent light 26, the convergent light 36, and the return light from the optical disc surface 2) are exactly received by the detectors 8a and 8b.
and a shielding plate 1 which also serves as an electrode in this case.
4 should be installed as shown in the figure. That is, if the optical disc surface 2 is shifted from the focused state to 28, the convergent light 36
a, a diverging light 31a is formed, and the right side of the optical path hits the shielding plate 14, and a focus error can be detected from the resulting electrical signal difference 8a-8b.

In the case of tracking error detection in (b), when the track groove 67 on the optical disc 2 is shifted as shown in the figure, the returned light follows optical paths such as 36c and 31c, so the electrical signal difference 8 a - 8 Tracking errors can be detected by e.

According to the embodiments shown in Parts 1 to 4, tracking is performed using an optical deflector and forcing is performed using an electrostatic actuator, without using a conventional heavy two-dimensional actuator consisting of a permanent magnet and a voice coil. , fine access can be executed at high speed, so both fine access and course access can be accelerated.

In addition, we adopted arc-shaped gratings for the gratings and r-ring elements that emit light from the waveguide to improve the accuracy of grate ink addition, and we also used bulk lenses for the converging elements. , to improve the light-gathering performance of optical discs.
-I can do 10 things.

Since various signals can be detected using the black O-order light that is always stably transmitted through the crating coupler, a stable detection optical system with no missing detection can be obtained.

FIG. 5 is a diagram showing the overall structure of another embodiment of the optical head 1 according to the present invention. In this embodiment, an electrostatic microactuator shown in FIG. 6 is used in place of the drive device 126 in the conventional example shown in FIG. 11. The electrostatic microactuator 100 of this embodiment has a cantilever 9 that has an objective lens 76 fixed to its tip and serves as a movable electrode.
8 and fixed electrodes 90 and 92. With this configuration, the objective lens 76 can be quickly moved in the radial direction and optical axis direction of the optical disk 78 so that the focused spot 80 follows a desired track, even when the focus and tracking directions change when the optical disk 78 rotates. It becomes possible to move to.

Next, the operation of this embodiment will be explained. The operation of the optical system for reading information on the optical disk 78 is basically the same as that of the conventional example shown in FIG. 11. That is, the light beam emitted from the semiconductor laser 68 with P polarization is passed through the collimating lens 7.
parallelized by 0, polarizing beam splitter CPBS
) 72, and is converted into circularly polarized light by a quarter-wave plate 74, and then condensed by an objective lens 76 to a diameter of about 1 μm on an optical disk 78, and focused on a light spot 80. The reflected light from the optical disk 78 is reflected by the objective lens 7
6, the light beam passes through a 1/4 wavelength plate 74, is converted into an S polarized beam, is reflected by a PBS 72, and is focused by a detection lens 82 onto a photodetector 84. In this way, the information recorded on the optical disc 78 can be read.

At this time, the focus error and tracking error of the focused spot 80 can be extracted by the photodetector 84 using the Foucault method, push-pull method, or the like.

The detection circuit 86 takes in the signal from the photodetector 84 and calculates focus error and tracking error. This calculation result is output to the translation circuit 88, and an operation signal for error correction using the electrostatic microactuator 100 is obtained. That is, when an error correction operation signal is applied to the fixed electrodes 90, 92 and the cantilever (movable electrode) 98, the objective lens 76 moves to the cantilever 100 according to the operating principle already explained using FIG. Since the lens moves along the optical axis along with the lens, focus can be controlled.

Further, for tracking control, a pair of electrodes may be provided in a plane orthogonal to the fixed electrodes 90 and 92, as described above.

In this embodiment, an optical head 100 is shown that reproduces information by changing the reflectance of an optical disk 78, but the present invention relates to a small and lightweight actuator that moves an objective lens, and any recording method on a disk may be used. Therefore, it can also be applied to, for example, a magneto-optical recording type optical head.

FIG. 7 is a diagram showing an example of the structure of a cantilever that performs both tracking and focusing.

In the figure, 78 is an optical disk, 104 is an optical pickup, 106 is an optical pickup mount, and 102 is an overall support. The support rod 102 is fixed to a linear motor for coarse tracking adjustment. Parts of the cantilever for tracking control and focus control are indicated by subscripts a and b, respectively. 90.92 is a fixed electrode, 94.96
is an electrode mount, and 98 is a cantilever.

In the embodiment shown in FIG. 5, an example was shown in which the objective lens 76 is moved to control focus and tracking, but in this embodiment, the entire integrated optical pickup 104 is moved. Cantilever 98a whose bending direction is different by 90 degrees,
If 98b is provided and tracking and focusing directions are set for each, control in both directions becomes possible with only this configuration.

FIG. 8 is a block diagram showing an example of the live circuit of the actuator shown in FIG. 7. This 1-live circuit is the 5th live circuit.
This corresponds to the detection circuit 86 and the one-rut motion circuit 88 in the figure.

Two tribe circuits are required for Toranoking River and Focusing, but only the Tribe circuit for Toranoking is shown here. In the figure, 108 is an I/racking error optical sensor on the center side of the disk, I-10 is a tracking error optical sensor on the outer side of the disk, and 112 is a differential amplifier. 1! iIi Amplifier 11: Meshi, Differential Amplifier 1
12 output ■. When is positive, '1', where k is a constant of proportionality
Hypolar 92, 1 V, = kV. , ■2-0 is output to the electrode 90a, and the output of the differential amplifier 112 is ■. When is negative, V,=O is output to the electrode 92a, and V,=kVo is output to the electrode 90a.

The tracking operation of the embodiment shown in FIG. 7 will be explained using FIG. 8. First, is the tracking off? The optical pickup 106 moves relatively to the inside of the disk. VR>VL
Suppose that it becomes As a result, V. <0, V2=k
As Vo, V■ = Q, an attractive force acts between the electrodes 90a and 94a, and the optical pickup 106 moves to the outside of the disk to correct the tracking deviation, and VR = Vc.
．． It stops where it becomes.

Regarding focusing, if we consider the focusing error signals as VR and VL and replace the subscripts a with b, we get
It can be thought of in the same way as tracking.

FIG. 9 is a diagram showing a schematic configuration of a floating optical head using an air slider. Proc. Int. Symp. o
n Optical Memory, 1987, p.
As shown in pll1 to pll116, a floating optical head using an air slider similar to a magnetic disk flies a semiconductor laser close to the optical disk, and uses reflected light from the optical disk to adjust the oscillation threshold of the semiconductor laser. The recorded information is reproduced by changing the . Therefore, almost no optical elements are required, making it possible to realize a small and lightweight optical head.

The actuation mechanism in the tracking direction is a one-stage actuator system that moves each arm.

Conventionally, it has been difficult to realize high-speed and highly accurate head movement in a wide movement range from 0.1 μm to several tens of meters using one seven actuator.

Therefore, sufficient tracking ability could not be obtained, and recording and reproduction could not be performed with a single head.In contrast, in the embodiment of the present invention shown in FIG. 9, macro seek and electrostatic micro High-speed and accurate tracking or focusing can be performed in two steps: micro-seek using an actuator. In Figure 9, 6
8 is a semiconductor laser, 78 is an optical disk, 84 is a photodetector, 100 is an electrostatic microactuator, 104 is an optical pickup, 114 is an arm, and 116 is an air slider.

The electrostatic microactuator 100 connects the semiconductor laser 68 and the photodetector 84 to the optical disk 7 using electrostatic force.
Move slightly in the radial direction of 8. That is, arm 11
By moving the optical head every 4 minutes, a few μm to several tens of ■
A macro seek of 0.1 μm to several μm or minute 1 ranking is performed using the lightweight microactuator 100. By having this two-stage actuation mechanism, the tracking ability of the floating optical head can be increased to a level that poses no problem in practical use. At this time, tracking errors cannot be detected due to minute tracking, but in order to detect tracking errors with a single photodetector, wobbling bits, such as those using the sample servo method, must be recorded on the optical disk in advance. It is appropriate to leave it as is.

According to this embodiment, since the actuator can be configured without using permanent magnets, coils, etc., the weight of the entire optical head can be reduced and the access speed can be increased.

〔Effect of the invention〕

According to the present invention, an optical head with high access speed, excellent single-beam performance, and excellent return light detection function can be obtained.

Furthermore, an optical head that does not use permanent magnets or coils, is lightweight, and has a high access speed is provided.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the overall structure of the first embodiment of the optical head according to the present invention, Fig. 2 is a diagram showing two embodiments of the grating element and optical path changes due to focus control, and Fig. 3 is a diagram showing an electric type optical head. FIG. 4 is a diagram showing an example of an optical system for detecting focus errors and traso-kink errors; FIG. 5 is an overall structure of another embodiment of an optical head according to the present invention. FIG. 6 is a diagram showing the principle of operation of the electrostatic microactuator of the embodiment shown in FIG. The figure is a block diagram showing an example of the drive circuit of the actuator of the present invention,
Fig. 9 is a diagram showing a schematic configuration of a floating optical head using an air slider, Fig. 10 is a diagram showing an example of a conventional integrated optical head, and Fig. 11 is a diagram showing the overall structure of an example of a conventional optical head. FIG. 2... Optical disk, 4... Optical head, 6... Semiconductor laser, 8... Photodetector, 10... Air (dielectric), 12.14... Electrode, 16... Power supply and control device, 18... Electrostatic actuator, 20... 2
Dimensional optical waveguide, 21... Laser waveguide light, 22... Arc-shaped grating element, 23... Concentrating grating coupler (FCC), 24... Objective lens, 26...
・Divergent light, 28... Lens mount, 30... Photodetector substrate (Si), 32... Cantilever substrate (Si)
). 34... Cantilever, 36... Convergent light, 38
...Convergent light. 40... Optical deflector, 44, 46.48
... electrode, 50 ... power supply, 52 ... refractive index distribution,
53... Crystal axis, 54... Disconnection, 56... TE mode, 58... Light wavefront, 60... Center line, 62... Light amplitude peak position, 64... Trasok direction, 66 ...
Direction perpendicular to 64, 68... semiconductor laser, 70...
Collimating lens, 72... PI3S (polarizing beam splitter), 74... 1/4 wavelength plate, 76... Objective lens, 78... Optical disk, 80... Focusing spot,
82...Detection lens, 84...Photodetector, 86...
・Detection circuit, 88...drive circuit. 90,. 92...
Fixed electrode, 94.96... Electrode mount, 95,97
...Movable electrode, 98...Cantilever (movable electrode),
100・Shizu' city type micro actuator, 10...
Support rod, 104... Optical pickup, 106... Optical pickup mount, 108, 110... Optical sensor for tracking error detection, 112... Differential amplifier, 1
14...Art t1, 116...Air slider, 1
18... Divergent waveguide light, 120... Concentrating grating coupler, 122... Beam splitter, 124...
- Focused light, 126... Drive device, 128... Coil, 130... Permanent magnet.

Claims (1)

[Scope of Claims] 1. An optical head including a light source that irradiates light onto an optical recording medium and a photodetector that detects reflected light from the optical information recording medium, wherein a dielectric material is connected to at least two electrodes. and a means for applying an external electric field to the actuator and the electrodes, the movable part of the actuator having at least one of the light source and an optical element that converts the light from the light source into diverging light or convergent light. An optical head characterized by spatially connected. 2. The optical head according to claim 1, wherein a light beam from the light source or the optical element is provided on an optical path between the light source or the optical element connected to the movable part of the actuator and the optical information recording medium. 2 condensing the emitted light to form a light spot on the optical information recording medium;
An optical head characterized by having a dimensional light condensing element. 3. The optical head according to claim 1 or 2, wherein the optical element that converts the light from the light source into diverging light or convergent light is a grating element on a two-dimensional or three-dimensional optical waveguide. light head. 4. The optical head according to claim 3, wherein the grating shape of the grating element is an arc, and the grating pitch changes from dense to sparse in the light propagation direction. 5. The optical head according to claim 3 or 4, further comprising an optical deflection element provided on the two-dimensional or three-dimensional optical waveguide. 6. The optical head according to claim 5, wherein the optical waveguide medium is a medium whose refractive index changes in response to an applied electric field, and the optical deflection element has the same shape as the light beam propagating in the optical waveguide. A first electrode is placed on the optical waveguide via a buffer layer, and second and third electrodes are placed between each of the first electrodes on the optical waveguide surface in a direction perpendicular to the light beam propagation direction. An optical head characterized in that it is an element provided with means for applying an electric field between the first electrode and the second and third electrodes. 7. The optical head according to any one of claims 1 to 3, further comprising means for causing the return light that passes through the grating element to enter the detector. 8. The optical head according to any one of claims 1 to 3 or 7, wherein the photodetector is divided into three parts in a track direction in a plane parallel to the optical information recording medium, and is arranged in a direction perpendicular to the track direction. Of the three divisions in the track direction, two adjacent divisions correspond to a focused spot formed on the photodetector surface when the spot concentrated on the optical information recording medium is in focus. The detection optical system is sized and positioned so that it can just receive the light, and has a detection optical system that has a shielding plate installed only on one of the boundaries in the track direction of the return optical path in the focused state at a position that does not overlap the return optical path. light head. 9. In an optical head including 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, a dielectric material is sandwiched between at least two electrodes; An optical head characterized in that one of the electrodes is fixed to a movable member, the movable member is used as an actuator element, and means is provided for applying an external electric field to the electrode. 10. The optical head according to claim 9, wherein an optical device includes an electrode in a movable state of the actuator element and at least a two-dimensional condensing element for condensing light from the light source onto the optical information recording medium. An optical head characterized by being spatially connected and integrated. 11. The optical head according to claim 9, wherein the movable electrode of the actuator element spatially moves in at least one of a direction along the surface of the optical information recording medium and a direction perpendicular to the surface. An optical head characterized in that: 12. The optical head according to claim 9, wherein the actuator element is incorporated in an air slider for floating the optical information recording medium close to the optical information recording medium. 13. The optical head according to claim 9, further comprising means for controlling the voltage value applied to the electrode to change the amount of movement of the electrode in the movable state of the actuator. 14. An optical disc device comprising the optical head according to any one of claims 1 to 13.