JP2003099974A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup which is simple, can be miniaturized, and has an excellent response speed. SOLUTION: In an optical pickup device 4 which is arranged movably opposedly to an optical disk 3 having recording layers, after the laser light of a laser diode 11 passes through a beam splitter 13 and so on, it is converged on the optical disk 3 through a wave front transformation element 14 formed by fixing a diffraction granting part in a form-changeable part, which changes in form in accordance with a driving voltage from an element driver 22, the first objective lens 16a and the second objective lens 16b. The focus position which is converged to the first and second recording layers is simply switched to jump over the layers to read out information recorded to the recording layers with good response jumping over the layers corresponding to the state whether the driving voltage is impressed or not impressed, and the miniaturization is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device used for reading information recorded on a recording medium by converging and irradiating the recording medium with light.

[0002]

2. Description of the Related Art In recent years, with the progress of the information industry, an optical information recording / reproducing apparatus is required to have a larger recording capacity. For example, high numerical aperture (NA
Specifically, (NA = 0.85) objective lens,
Research on a next-generation optical disc having a recording capacity of 25 GB using a blue LD (wavelength 405 nm) has begun. Since this method has a high NA, the aberration caused by the error in the substrate thickness and the tilt becomes severe. Therefore, an aberration correction technology using a liquid crystal panel having a phase distribution has been proposed.

Furthermore, studies have also begun to increase the density by forming recording films into multiple layers. In multi-layer recording, a layer jump technique of 20 to 30 μm is required in addition to the aberration correction technique described above. It has been proposed to insert an expander directly below the objective lens and perform layer jump (Jpn. J. App.
l. Phys. 39, 937 (2000)).

[0004]

However, when a liquid crystal panel is used, the response speed of the liquid crystal is very slow. There is also a problem that the pickup becomes large when an expander is used. Further, the aberration can be corrected only when the substrate thickness is in an error range.

(Object of the Invention) The present invention has been made in view of the above points, and an object of the present invention is to provide an optical pickup device which is simple and can be miniaturized and has a good response speed.

[0006]

[MEANS FOR SOLVING THE PROBLEMS] A wavefront deforming element for changing a wavefront of light emitted from a light emitting portion, and an objective lens for condensing light having a wavefront changed by the wavefront deforming element on a recording surface of a recording medium. In the provided optical pickup device, the wavefront deformation element is attached to a shape-variable member,
By making the wavefront of light change according to the shape of the shape-variable member, it is possible to make the size simple and small.

Further, the shape-variable member has a structure in which its shape is changed by electrostatic force when a voltage is applied, and the wavefront deformation element is attached to a portion where the shape is changed, and has a good responsiveness. I am trying.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIGS. 1 to 6 relate to a first embodiment of the present invention. FIG. 1 shows a configuration of an optical reproducing apparatus having the first embodiment, and FIG. FIG. 3 shows a structure of an optical disc having a plurality of recording layers, FIG. 3 shows a structure of a lens actuator, FIG. 4 shows a structure of a wavefront deformation element and the like,
FIG. 5 shows how the shape of the wavefront deforming element changes with and without voltage applied, and FIG. 6 schematically shows the optical characteristics of the wavefront deformable element with and without voltage applied. .

As shown in FIG. 1, in the optical reproducing apparatus 1 having the first embodiment of the present invention, the spindle motor 2 is used.
An optical pickup device (hereinafter, abbreviated as an optical pickup or a pickup) 4 is arranged on a movable table so as to face the optical disk 3 which is driven to rotate by a voice coil motor (abbreviated as VCM) 5. It is movable in the radial direction.

The voice coil motor 5 is connected to the drive controller 6 and moves the pickup 4 under the control of the drive controller 6 so as to seek to the designated track. Further, the drive controller 6 is connected to an external host computer 7, and when receiving a signal for reproducing information from the host computer 7, moves the pickup 4 via the voice coil motor 5 so as to reproduce corresponding information. .

The pickup 4 is provided with a blue laser diode 11 which emits a blue wavelength of 405 nm, for example, and the laser light generated by this laser diode 11 is collimated by a collimator lens 12 into a parallel light beam and incident on a beam splitter 13. Then, a part of the light is transmitted and is incident on the wavefront deformation element 14 that constitutes the condensing optical system. The wavefront transforming element 14 causes the first-order diffracted light to be incident on the first objective lens 16a, and is further focused and irradiated onto the optical disc 3 via the second objective lens 16b (note that the 0th-order and -1st-order diffractions are performed. Light is not used).

The light reflected by the optical disk 3 enters the wavefront deforming element 14 through the objective lenses 16b and 16a, and the wavefront deforming element 14 causes the first-order diffracted light to enter the beam splitter 13, and the reflected light is condensed. The light is collected by the lens 17 and received by the photodetector 18.

The output signal photoelectrically converted by the photodetector 18 is input to the signal processing circuit 19, and from the reflection signal due to the pits recorded on the optical disc 3, the track and the ID portion of the sector obtained by dividing the track into a plurality of sections are recorded. The address data and the recording data in the data part following the ID part are demodulated and sent to the drive controller 6. Then, it is possible to seek to a desired recording area and send the information reproduced from the recording area to the host controller 7.

The laser diode driver 20 controls the amount of light emitted from the laser diode 11. The laser diode driver 20 is controlled by the drive controller 6, and the light emission amount is controlled so that a reflection signal of an appropriate level can be obtained from an arbitrary track such as the inner circumference side or the outer circumference side of the optical disc 3. In the present embodiment, the optical disc 3 has a structure having multiple recording layers as shown in FIG.

That is, in this optical disc 3, the first and second recording layers 21a and 21b are respectively provided at a distance of 75 μm and 100 μm (from the pickup 4 side), and in this embodiment, the laser beam is condensed. As the converging optical system for irradiation, the wavefront deformation element 14 is adopted together with the two objective lenses 16a and 16b, and the wavefront deformation element 14 is changed in its optical characteristics by the element driver 22 so that any recording layer can be formed. Another feature is that light can be condensed and emitted in a spot shape.

In this case, the shape of the wavefront deforming element 14 is deformed by the electrostatic force due to the application of a voltage to change its optical characteristics, and the two recording layers 21 are satisfactorily responsive.
A layer jump between a and 21b can be performed.

As shown in FIG. 3, the two objective lenses 16a and 16b and the wavefront deformation element 14 are provided with a lens frame 24.
This lens frame 24 is movable in a minute range in the optical axis direction of the optical system and in the direction traversing the track by a lens actuator provided with a magnet 25 and a focusing & tracking coil 26.

In the lens actuator of FIG. 3, in addition to the objective lenses 16a and 16b, the wavefront deformation element 14 is a lens frame 24.
It has the same configuration as a normal lens actuator except that it is attached to the.

FIG. 4 shows the detailed construction of the wavefront deformation element 14 and the like. As shown in FIG. 4 (A), the wavefront deforming element 14 has a substantially cylindrical shape, and its upper surface is deformed by electrostatic force due to electrostatic force. The diffraction grating section 31 is formed, and the top surface shape is changed by the shape changing section 30, so that the grating interval (grating pitch) in the radial direction of the diffraction grating section 31 is changed and the light is emitted through the diffraction grating section 31. The wave front of the light is variably controlled.

The diffraction grating portion 31 is designed to have a narrower grating spacing toward the outer peripheral side so that it has a function as a lens for condensing light. That is, the objective lens 1
A large number of diffraction gratings are formed in a concentric ring shape around the optical axes of 6a and 16b, and the grating spacing is narrower toward the outer peripheral side.

The shape varying portion 30 having the diffraction grating portion 31 mounted on the upper surface thereof is a transparent, disk-shaped holding portion 32, a ring-shaped supporting portion 33 provided on the upper surface of the holding portion 32, and this supporting portion. 33 transparent electrodes (provided on the entire surface) provided on the upper and lower surfaces (so as to face each other at a height)
4 and a plurality of electrodes 35 provided in a concentric ring shape,
The diffraction grating portion 31 is attached to the upper surface of the electrode 34 by adhesion or the like.

A plurality of electrodes 35 on the lower surface provided on the upper surface of the holding portion 32 are opposed to the electrodes 34 provided on the entire upper surface.
Are formed of a plurality of electrode segments 35a, 35b, ... Concentric ring-shaped as shown in FIG. 4 (B) (shown in three cases for simplification in FIG. 4 (B)). . Note that FIG. 4B shows a structure in which the portion where the electrode 35 is provided and the portion where the electrode 35 is not provided are equidistant, but the interval between the portions not provided with the electrodes may be made narrower.

Then, the voltage applied to the electrode 34 and the plurality of electrode segments 35i (i = a, b, ...) Is controlled by the element driver 22 so that an electrostatic force acts between them and the electrode 34 on the upper surface. The shape on the side, that is, on the side of the diffraction grating portion 31 can be deformed.

The holding portion 32 is formed of, for example, a glass substrate of about several mm, the diffraction grating portion 31 is formed (deformable) of polyimide having a thickness of, for example, several μm, and the support portion 33 is formed of, for example, Si. The electrodes 34 and 35 are made of, for example, an ITO substrate having a thickness of several μm. The electrode 34 and the side of the diffraction grating portion 31 attached to the upper surface thereof are formed of a thin ITO substrate and a polyimide, respectively, and can be deformed when an electrostatic force described later is applied. On the other hand, since the electrode 35 is attached to the thick glass substrate, it is hardly deformed by the electrostatic force described later.

In the present embodiment, when the diffraction grating portion 31 side is deformed, the electrode 34, which is on the ground side, for example, is provided by the element driver 22 so that the shape can be finely controlled.
On the other hand, the voltage applied to each electrode segment 35i can be variably set.

Specifically, the element driver 22 calculates the information corresponding to the voltage applied to each electrode segment 35i by the control signal from the drive controller 6, and the information calculated by the calculating section 36, for example, It is composed of an electronic potentiometer (abbreviated as EVR) 37i whose resistance value is electrically variably set, and is connected to each electrode segment 35i with a predetermined power source voltage Vc and a reference resistance (not shown). ) Electronic volume 37i
A voltage corresponding to the resistance value of the electronic volume 37i is applied via.

In this way, the element driver 22 controls the voltage applied to each of the plurality of electrode segments 35i (i = a, b, ...) By setting the potential of the electrode 34 on the ground side to zero. The state shown in FIG. 5 (A) where no voltage is applied can be changed as shown in FIG. 5 (B).

Incidentally, as described above, the electrode segment 35i
Since the side is attached to the upper surface of the holding portion 32 formed of hard glass, the electrode segment 35i side is not deformed.

In the present embodiment, the electrode segment 35i
When no voltage is applied to the first recording layer 21a (that is, the recording layer located at a distance of 75 μm from the pickup side) of the optical disc 3 in a state where the laser beam can be focused and irradiated, as shown in FIG. 6 (A). The optical optics is set.

Then, when reproducing the information recorded by seeking to the second recording layer 21b (that is, the recording layer located at a distance of 100 μm from the pickup side), the drive controller 6 calculates the element driver 22 36), a control signal is sent to the calculation unit 36, the calculation unit 36 receives the control signal, generates corresponding information, and controls the voltage applied to each electrode segment 35i by the information. And FIG.
As shown in (B), the focusing optical system is set so that the second recording layer 21b of the optical disc 3 can be focused and irradiated with the laser beam.

Note that in FIG. 6B, the grating spacing of the diffraction grating portion 31 becomes relatively longer by applying a voltage than in the case of FIG. 6A. In comparison, in FIG. 6B, the number of grids is schematically reduced (that is, the grid spacing is increased).

Further, in the state of FIG. 6A, the objective lenses 16a and 16b and the wavefront deforming element 14 in the state in which no voltage is applied generate almost no aberration on the first recording layer 21a. It is optimized so that it can be focused and irradiated.

When the focus is switched to the second recording layer 21b, the error caused by the error in the optical disk substrate thickness and the aberration caused by the objective lenses 16a and 16b are also larger than those in the case of the first recording layer 21a. First recording layer 2
Although larger than in the case of 1a, these aberrations are set within an allowable range by optimizing the shape of the wavefront deformation element 14 and absorbing it.

Although the diffraction grating portion of the diffraction grating portion 31 is simplified and shown in a sawtooth waveform in FIG. 6 and the like, in the present embodiment, for example, as shown in FIG. A diffraction grating portion is formed, and in this case, when the height d of the unevenness is the wavelength of the laser light, 1 /
A phase zone plate having a phase difference of 2, that is, a phase difference of π is formed. By doing so, the function of erasing the diffracted light of the 0th order in the transmitted light of the concave portion and the convex portion is increased.

Next, the operation of reading the information recorded on the optical disk 3 by the optical reproducing apparatus 1 having the above-mentioned structure will be described. In the present embodiment, for example, in the file allocation table in the first recording layer 21a of the optical disc 3, file allocation information in all tracks of the first recording layer 21a and in all tracks of the second recording layer 21b are recorded. The file layout information is recorded.

When the host computer 7 instructs the drive controller 6 of the optical reproducing apparatus 1 to read the file recorded on the optical disc 3, the drive controller 6 first instructs the voice coil motor 5 to move. The optical pickup 4 is moved by the voice coil motor 5 to the vicinity of the track where the file allocation table of the optical disc 3 is recorded.

Then, the lens actuator is controlled to set the focusing optical system to the focusing state and the tracking state, the address information of the track is read, and the address information of the track in which the file allocation table is recorded is read. If there is, the information is read from the file allocation table of that track, and if it is a different track, a track jump or the like is performed to access the track on which the target file allocation table is recorded.

In this case, the element driver 22 is in a state in which no voltage is applied to the wavefront deforming element 14, and in this state, as shown in FIG. 6A, the converging optical system is the first recording layer 2
It is in a state where the laser beam can be focused and irradiated on 1a.

In other words, in the optical pickup 4 in this state, the laser light is used for the wavefront deformation element 1 which forms the focusing optical system.
4, first objective lens 16a, second objective lens 16b
Then, the first recording layer 21a is irradiated with the light focused in a spot shape. Then, the reflected light is the photodetector 1.
The light is received at 8, and demodulated by the signal processing circuit 19 to read the address information of the prepit portion and the recording information of the file arrangement of the data portion.

The drive controller 6 judges from the information of the file allocation table which track the file instructed to be read is stored in, and again the voice is read so as to access the track in which the instructed file is recorded. The coil motor 5 moves the optical pickup 4 to a track in the vicinity thereof. In this case, the target file is the first recording layer 2
In the case of 1a, the track in which the target file is recorded is accessed almost as in the case of the file allocation table.

On the other hand, when the target file is on the second recording layer 21b, it is similar to the case of the first recording layer 21a, but the drive controller 6 sends a control signal to the element driver 22, The element driver 22 applies a voltage to each electrode segment 35i so that the second recording layer 21b can be irradiated with light in a focused state.

Then, by accessing the target track and reading the information of the target file from the track, the information is sent to the host controller 7 via the drive controller 6.

As described above, the optical pickup 4 is constructed by using the wavefront deformation element 14 provided with the diffraction grating portion 31 which can change the grating spacing of the diffraction grating by applying the voltage (adopting the condensing optical system formed by the wavefront deformation element). Therefore, the focus position of the focusing optical system can be quickly and variably set on each recording layer by controlling the appropriate voltage application to the electrode segment 35i for the information recorded on the plurality of recording layers.

In this case, the wavefront deformation element 14 has a simple structure, and if the voltage applied to the electrode segment 35i is variably set, the optical characteristics of the wavefront deformation element 14 can be changed and controlled. Can be made small.

Further, for example, from the first recording layer 21a to the second recording layer 21a
In the case where the light beam focused and irradiated on the recording layer 21b is subjected to the layer jump, the aberration caused by the error in the substrate thickness of the optical disc 3 and the aberrations caused by the objective lenses 16a, 16b and the like are allowed by the shape correction of the wavefront deformation element. It can be corrected within. That is, it is possible to realize a pickup that can be made compact with respect to a large capacity optical information reproducing apparatus.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. 7 and 8. FIG. 7 shows the configuration of an optical reproducing device provided with the optical pickup of the second embodiment, and FIG. 8 shows an explanatory view of the function of the condensing optical system according to the present embodiment.

As shown in FIG. 7, in the optical reproducing apparatus 1B having the second embodiment of the present invention, in FIG. 1, the condensing optical system is composed of one objective lens 16 and the wavefront deforming element 14. The optical pickup 4B is used.

Further, in the optical pickup 4B, a polarization beam splitter 41 is adopted instead of the beam splitter 13. Then, the laser light passing from the laser diode 11 through the collimator lens 12 enters the polarization beam splitter 41 as S-polarized light, and almost all the incident light passes through the polarization beam splitter 41. The transmitted light becomes circularly polarized light by the quarter-wave plate 42, is condensed by the wavefront deformation element 14 and the objective lens 16 and is condensed and irradiated on the optical disc 3.

Further, the reflected light from the optical disk 3 passes through the objective lens 16 and the wavefront deforming element 14, and is passed through the quarter-wave plate 42.
And the transmitted light becomes P-polarized light, and almost all is reflected by the polarization beam splitter 41.
The light is then received by the photodetector 18. By changing the beam splitter 13 of the first embodiment as described above, the light utilization efficiency is improved.

The wavefront deforming element 14 of the present embodiment has the same structure as that of the first embodiment, but the function of the convex lens in the case of the first embodiment is made larger (specifically, diffraction is performed). As described in the first embodiment, the lattice spacing of the lattice portion is made smaller on the outer peripheral side, but in the present embodiment, the tendency is made more remarkable). Further, in the present embodiment, the objective lens 16 and the wavefront deforming element 14 having a function of condensing like a convex lens are set to have an achromatic lens function.

The wavelength of the laser light emitted from the semiconductor laser diode 11 changes depending on the ambient temperature or the like. Therefore, particularly when reproducing information recorded at high density, the refraction function of the objective lens 16 also changes due to the change in the wavelength of the laser light.

In the objective lens 16, as the wavelength becomes longer, the refractive index becomes smaller as shown in FIG. 8 (A). In contrast, the shorter the wavelength of the diffraction grating section 31, the larger the refractive index (diffraction function).

Therefore, by properly combining both, the function of the convex lens for converging both can be maintained,
It is possible to form a condensing optical system that is not affected by a change in wavelength, that is, functions as an achromatic lens.

In the conventional example, a concave lens is combined to correct chromatic aberration, but a convex lens having a short focal length is required due to the concave lens, and a condensing optical system having an achromatic function becomes large, Although there is a drawback that distortion and the like tend to become large, in the present embodiment, the function of a convex lens is still provided by the diffraction grating portion 31 of the wavefront deforming element 14 (refractive characteristics of wavelengths are reversed). Since an achromatic lens can be formed with the objective lens 16, a compact and lightweight condensing optical system can be realized. Further, the convex lens 16 alone can be used with a longer focal length, and the occurrence of distortion can be suppressed. The other configurations are the same as those in the first embodiment. Further, the operation of the present embodiment is almost the same as that of the first embodiment except for the portion of the condensing optical system (as described above, compared to the first embodiment, the beam splitter 13 has Instead, a polarization beam splitter 41 and a quarter-wave plate 42 are adopted to improve the light utilization rate).

Further, according to the present embodiment, the same effect as that of the first embodiment can be obtained, and further, the condensing optical system can be constituted by a smaller number of optical elements and the influence of chromatic aberration can be absorbed. . Therefore, even when the wavelength changes with temperature like a semiconductor laser, high-density information reproduction can be performed by absorbing chromatic aberration.

FIG. 9 shows a modified wavefront deforming element 14 '. This wavefront deforming element 14 'basically has the holding portion 32 in the wavefront deforming element 14 shown in FIG.
1, the condensing optical system (objective optical system) can be formed only by the wavefront deforming element 14 '.

That is, in FIG. 7, the condensing optical system is formed by the wavefront deforming element 14 and the objective lens 16, but the function is constituted only by this wavefront deforming element 14 '.

In the wavefront deformation element 14 'shown in FIG.
A diffraction grating part 31 formed of a transparent member such as polyimide that can be deformed is arranged facing the quarter wave plate 42 side. A transparent electrode 34 is provided on the entire upper surface of the diffraction grating portion 31. Further, the upper end of the ring-shaped support portion 33 whose lower end abuts on the peripheral edge of the diffraction grating portion 31 has the holding portion 3
The plano-convex lens 52 having the dual function is brought into contact with the peripheral portion of the plane portion and is fixed by adhesion or the like.

Further, on the plane portion of the plano-convex lens 52 inside the support portion 33, the electrode 3 formed of concentric ring-shaped electrode segments is provided.
5 is formed. The electrodes 34 and 35 are connected to the element driver 22.

According to this modification, since the function of the objective lens 16 can be realized by the holding portion which constitutes the wavefront deforming element 14 ', the lens actuator can be made smaller and lighter, and a high-speed optical pickup can be realized. This can be realized and the power consumption for driving the optical pickup can be suppressed.

[Additional Notes] 1. The optical device according to claim 6, wherein the optical device is a one-light type in which a convex lens portion is integrally provided. 2. 7. The optical device according to claim 6, wherein transparent electrodes are provided on both ends of the ring-shaped support portion, and the diffraction grating portion is deformably disposed on one transparent electrode side,
The diffraction grating portion is deformed by the electrostatic force acting between the transparent electrodes due to the application of the voltage, and the lattice spacing is changed by the deformation to control the traveling direction of the diffracted light.

[0062]

As described above, according to the present invention, the wavefront deformation element for changing the wavefront of the light emitted from the light emitting portion and the light having the wavefront changed by the wavefront deformation element are collected on the recording surface of the recording medium. In an optical pickup device including an objective lens for making light illuminate, the wavefront deforming element is attached to a shape-changing member, and the wavefront of light changes according to the shape of the shape-changing member. You can

Further, the shape-variable member has a structure in which its shape is changed by electrostatic force due to application of a voltage, and the wavefront deformation element is attached to a portion where the shape is changed, and has a good responsiveness. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical reproducing device including an optical pickup according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an optical disc having multiple recording layers.

FIG. 3 is a diagram showing a configuration of a lens actuator.

FIG. 4 is a diagram showing a configuration of a wavefront deformation element or the like.

FIG. 5 is a diagram showing how the shape of a wavefront deforming element changes when a voltage is not applied and when a voltage is applied.

FIG. 6 is a diagram schematically showing optical characteristics of the wavefront deforming element when a voltage is not applied and when a voltage is applied.

FIG. 7 is a block diagram showing a configuration of an optical reproducing device including an optical pickup according to a second embodiment of the present invention.

FIG. 8 is an explanatory diagram of functions of two optical elements that form the condensing optical system.

FIG. 9 is a diagram showing a configuration of a wavefront deforming element according to a modification of the second embodiment.

[Explanation of symbols]

1 ... Optical playback device 2 ... Spindle motor 3 ... Optical disc 4 ... Optical pickup (device) 5 ... Voice coil motor 6 ... Drive controller 7 ... Host controller 11 ... Laser diode 13 ... Beam splitter 14 ... Wavefront deformation element 16a, 16b ... Objective lens 18 ... Photodetector 19 ... Signal processing circuit 20 ... Laser diode driver 21a, 21b ... Recording layer 22 ... Element driver 30 ... Shape changing part 31 ... Diffraction grating part 32 ... Holding unit 33 ... Supporting part 34, 35 ... Electrodes 36 ... Calculation unit 37 ... Electronic volume

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H049 AA04 AA14 AA16 AA43 AA57                       AA61                 5D119 AA01 BA01 BB13 EC03 JA09                       JA70                 5D789 AA01 BA01 BB13 EC03 JA09                       JA70

Claims (6)

[Claims] 1. An optical pickup comprising: a wavefront deforming element for changing a wavefront of light emitted from a light emitting section; and an objective lens for condensing light having a wavefront changed by the wavefront deforming element onto a recording surface of a recording medium. In the device, the wavefront deformation element is attached to a variable shape member, and the wavefront of light changes according to the shape of the variable shape member. 2. The shape-changing member changes its shape by an electrostatic force when a voltage is applied, and the wavefront deforming element is attached to a portion where the shape changes. Optical pickup device. 3. The optical pickup device according to claim 1, wherein the wavefront deformation element is formed by a concentric ring-shaped diffraction grating. 4. The optical pickup device according to claim 1, wherein the wavefront deformation element has a function of a convex lens. 5. The optical pickup device according to claim 1, wherein the wavefront deformation element has a function of an achromatic lens that compensates for chromatic aberration caused by the objective lens. 6. An optical pickup device comprising a condensing optical system for condensing and irradiating light onto an optical recording medium, comprising: a diffraction grating portion formed of a transparent member capable of deforming the condensing optical system; The optical pickup device is formed by an optical device having a shape-changing member that is capable of deforming the surface on which the diffraction grating portion is attached by applying the voltage.