JP2003067969A - Optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup which can input and output to a recording medium of base plates different in thickness and is small in power consumption with less noise but with quick response and mechanically simple and contributes to cost reduction. SOLUTION: In an optical pickup of an optical recording/reproducing device which has a light source 2, an objective lens 7, and a reflecting mirror to bend 90 degrees the laser beam from the light source 2 to irradiate the objective lens, the reflecting mirror consists of a mirror surface which can change its shape, and a variable mirrors 6 with a surface changing means to change the above mirror surface. By changing the above mirror surface, the laser beam can be condensed to input and output to the recording medium 8 of the base plates having different thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup used in an optical recording / reproducing apparatus for recording information on an optical disc such as a CD or DVD and reproducing the recorded information.

FIG. 37 is a schematic diagram showing a conventional example of a general optical pickup of this type. The conventional optical pickup 1'includes a light source 2 including a laser diode (LD), an objective lens 7, and a laser beam from the light source 2
It has at least a mirror 6 ′ that bends at 0 ° and irradiates the objective lens 7. The recording medium 8 is set at the focus position of the objective lens 7. Others, Figure 3
The optical pickup 1 ′ of 7 has a polarization beam splitter 4 and a wave plate 5 between the laser diode 2 and a mirror 6 ′, and a condenser lens 9 in one optical path separated by the polarization beam splitter 4. It has a photodetector 10 composed of a photodiode or the like. In addition, the objective lens 7
Can be moved in a direction parallel to the recording medium and along the optical axis via a drive control means (not shown).

In the conventional optical pickup 1'having such a structure, the laser light is emitted from the light source 2 and becomes parallel light via the collimator lens 3. The collimated laser light is polarized beam splitter (Tp = 70%, R
s = about 100%) 4. The P-polarized light of the incident laser light passes through the polarization beam splitter 4, becomes circularly polarized light through the wave plate 5, and is incident on the mirror 6 ′. Further, the light is reflected by the mirror 6 ′, bent 90 degrees, condensed through the objective lens 7, and irradiated onto the recording medium 8.
The laser light reflected by the recording medium 8 follows the opposite path, is reflected again by the mirror 6 ′, is bent 90 degrees, becomes linearly polarized light through the wave plate 5, and becomes the polarization beam splitter 4
S-polarized light is incident on. The S-polarized laser light is reflected by the polarization beam splitter 4, condensed through the condenser lens 9, received by the photodetector 10, and transmitted through the central processing unit (not shown) or the like to the servo signal, Information signals can be obtained.

Of the servo signals, the focus error signal uses a beam size method, an astigmatism method, or the like, which is a known technique. Specifically, the objective lens 7 is driven in the optical axis direction to defocus on the recording medium 8, and in this state, the return light to the photodetector 10 is detected. Similarly, the track-error signal uses the well-known technique such as Push-Pull method. Specifically, the focus error signal (defocus amount) is detected by detecting by driving the objective lens 7 in parallel with the surface of the recording medium 8. The information signal is obtained by detecting the amount of light received by the photodetector 10.

[0005]

By the way, a recording medium used for an ordinary optical pickup has two different substrate thicknesses such as a CD having a substrate thickness of 1.2 mm and a DVD having a substrate thickness of 0.6 mm. It is roughly divided into things. However, in an optical system that constitutes a conventional optical pickup, for example, when a condenser lens is adjusted to a predetermined position, a CD and a DVD
As described above, it is designed so that spherical aberration does not occur in accordance with either one of recording media having different substrate thicknesses. Moreover, the condensing lens that constitutes such an optical system is composed of a lens manufactured by polishing glass or an aspherical lens, and the focal length cannot be changed by deforming the lens itself. Since the mirror 6'is also formed by providing a reflective film on a transparent member such as glass which does not deform, it is impossible to change the focal length by deforming the mirror 6 'itself. Therefore, in the conventional optical pickup,
When a recording medium having the other substrate thickness is set, spherical aberration occurs, and it is impossible to simultaneously input and output two types of recording media having different substrate thicknesses.

Further, when the objective lens is driven in the optical axis direction in order to detect the focus error signal (defocus amount), a driving device for that purpose is required and the mechanical structure is complicated. Since a motor or the like is used to move the objective lens, there are drawbacks such as high power consumption, loud noise, long response time, long lens movement, and high cost.

Therefore, the present invention has been made in view of these problems.
Light that can be input and output to and from any of recording media with different substrate thicknesses, has low power consumption, quiet noise, short response time, simple mechanical structure, and contributes to cost reduction. It is intended to provide a pickup.

[0008]

In order to achieve the above object, an optical pickup according to the present invention comprises at least a light source, an objective lens, and a reflecting mirror for bending a laser beam from the light source by 90 degrees and irradiating the objective lens. In the optical pickup of the optical recording / reproducing apparatus having the above, the reflection mirror is composed of a variable mirror having a mirror surface whose shape is changed and a surface shape changing means for changing the shape of the mirror surface. To do.

Further, the optical pickup according to the present invention includes at least a light source, an objective lens, and a reflecting mirror for bending the laser light from the light source 90 degrees and irradiating the objective lens.
In an optical pickup of an optical recording / reproducing apparatus having a recording medium, the reflection mirror is composed of a variable mirror having a mirror surface whose shape is changed, and surface shape changing means for changing the shape of the mirror surface, By changing the shape of the mirror surface, it is possible to collect the laser light so that the laser light can be input to and output from the recording media having different substrate thicknesses.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of an optical pickup according to the present invention. The optical pickup 1 according to the present embodiment has a mirror surface whose shape is changed instead of the undeformed mirror 6 ′ provided in the optical pickup 1 ′ shown in FIG. 37, and surface shape changing means for changing the shape of the mirror surface. The variable mirror 6 is provided with. The recording medium 8 is set at the focus position of the objective lens 7. In addition, the optical pickup 1 of this embodiment
Has a polarization beam splitter 4 and a wavelength plate 5 between the laser diode 2 and a mirror 6 ′, and a condenser lens 9 is provided in one optical path separated by the polarization beam splitter 4.
It has a photodetector 10 composed of a photodiode or the like.

In the optical pickup 1 of this embodiment, the shape of the mirror surface of the variable mirror 6 is changed to reduce the spherical aberration, and it is possible to input / output two types of recording media having different substrate thicknesses. It is configured so that the laser light can be condensed.

The conventional optical pickup 1'shown in FIG.
Objective lens 7 is optimized for a recording medium having a substrate thickness of 0.6 mm, and the spherical aberration for a recording medium having a substrate thickness of 0.6 mm is good at an image height of about 1 deg as shown in FIG. 2 (a). It is a value. However, with respect to a recording medium having a substrate thickness of 1.2 mm, a large amount of spherical aberration occurs on the + side as shown in FIG. 2 (b). Therefore, the optical pickup 1 of the present embodiment
Then, when inputting / outputting the recording medium having the 1.2 mm substrate thickness, the shape of the mirror surface of the variable mirror 6 can be changed as shown in FIG. 3 (a). Then,
The spherical aberration is corrected, and good spherical aberration can be obtained almost as shown in FIG. Therefore, according to the present embodiment, it is possible to realize an optical pickup capable of inputting / outputting to / from recording media having two different substrate thicknesses.

Further, in the optical pickup 1 of the present embodiment, the variable mirror 6 is configured by changing the shape of the mirror surface so as to correct the aberration and the like caused by the manufacturing error of the recording medium. it can. Therefore, examples of those configurations will be described next. In a high-density optical pickup having a high NA of an objective lens, the influence of spherical aberration caused by a thickness error of a recording medium is large. Therefore, in the optical pickup 1 of FIG. 1, if the variable mirror 6 is configured such that the shape of the mirror surface is deformable as shown in FIG. 3B, the spherical aberration on the + side can be corrected. If it is configured to be deformable into a shape as shown in FIG. 3 (a), it is possible to correct the − side spherical aberration.

Further, coma aberration occurs due to the inclination and warpage of the recording medium. Therefore, coma can be corrected by configuring the variable mirror 6 so that the shape of the mirror surface can be changed to the shape shown in FIGS. 3 (c) and 3 (d). Further, since coma aberration is usually generated due to the inclination or warp of the recording medium in the radial direction, the coma aberration in the radial direction is corrected.
It may occur in the radial direction. In this case, the variable mirror 6 is configured to be deformable in the two-dimensional direction by the shape of the mirror surface as shown in FIGS. 3 (c) and 3 (d). Correction is possible. Furthermore, the shape of the mirror surface of the variable mirror 6 is shown in FIGS.
By being configured to be deformable into a combination of the shapes shown in (d), it becomes possible to correct spherical aberration and coma at the same time.

Further, in the optical pickup 1 of this embodiment,
As shown in FIGS. 4A to 4C, the focus error signal shown in FIG. 5 is detected by deforming the shape of the mirror surface of the variable mirror 6. As described above, in the conventional ordinary optical pickup 1 ′ shown in FIG. 37, the objective lens 7 is driven in the optical axis direction to defocus on the recording medium 8, and in this state, the light is detected by the photodetector 10. The focus error signal (defocus amount) is detected by detecting the return light.

On the other hand, the optical pickup 1 of this embodiment
As shown in FIGS. 4 (b) and 4 (c), by transforming the shape of the mirror surface of the variable mirror 6 into a convex surface and a concave surface, the parallel light is converted into divergent light and converged light, respectively, and is recorded on the recording medium 8. Causes defocus. As a result, a signal (the same signal as the focus error signal) as shown in FIG. 5 is obtained with respect to the amount of deformation of the mirror surface of the variable mirror 6. Therefore, according to the optical pickup 1 of the present embodiment, it becomes possible to detect the focus error signal as in the case of driving the objective lens 7 used in the conventional optical pickup 1 ′, and the signal output becomes zero. If the deformation of the mirror surface of the variable mirror 6 is controlled so that the laser light can be focused on the recording medium 8 in an input / output manner. (This is called focus servo).

Further, in the optical pickup 1 of the present embodiment, as shown in FIGS. 6 and 7A to 7C, the variable mirror 6 can be deformed so that the shape of the mirror surface is flat or convex. Alternatively, as shown in FIGS. 8 and 9A to 9C, the variable mirror 6 may be configured such that the shape of the mirror surface can be changed to a flat surface or a concave surface. With such a configuration, the mirror surface of the variable mirror 6 can be deformed in only one direction, so that the configuration of the variable mirror 6 can be simplified as compared with the configuration of FIG.

Further, the variable mirror 6 has a transparent electrode divided into a plurality of parts and is made of a piezoelectric material, a permanent magnet or coil arranged near the mirror surface, and the mirror surface are integrated. It is possible to use a member having a transparent member capable of passing a transparent current and configured to change the surface shape by an electromagnetic force. Therefore, a specific configuration of the variable mirror applicable to the optical pickup of the present invention will be described below with reference to embodiments.

FIG. 10 is a schematic configuration diagram of a Kepler type finder of a digital camera using a deformable mirror applicable to the variable mirror used in the optical pickup of the present invention. The configuration of this embodiment can be used in a silver halide film camera, of course. First, the variable mirror 409 will be described.

The variable shape mirror 409 is an optical characteristic variable shape mirror (hereinafter, simply referred to as variable shape mirror) consisting of an aluminum-coated thin film (reflection surface) 409a and a plurality of electrodes 409b, and 411 is each electrode 409b. A plurality of variable resistors 412 respectively connected to the thin film 409a and the electrode 409 via a variable resistor 411 and a power switch 413.
power source 414 connected between terminals b, a plurality of variable resistors 41
Arithmetic unit for controlling the resistance value of 1; 415, 416
Reference numerals 417 and 417 respectively denote a temperature sensor, a humidity sensor and a distance sensor connected to the arithmetic unit 414, which are arranged as shown in the drawing to form one optical device.

The objective lens 902 and the eyepiece lens 90
1, prism 404, isosceles right angle prism 40
5, each surface of the mirror 406 and the deformable mirror may not be a flat surface, and may be a spherical surface, a rotationally symmetric aspherical surface, a spherical surface decentered with respect to the optical axis, a flat surface, a rotationally symmetric aspherical surface, or a symmetric surface. It may have any shape such as an aspherical surface having, an aspherical surface having only one symmetrical surface, an aspherical surface having no symmetrical surface, a free-form surface, a surface having non-differentiable points or lines, and a reflecting surface. A refracting surface may be any surface that can affect light. Hereinafter, these surfaces are collectively referred to as an extended curved surface.

The thin film 409a is made of, for example, P. Rai-ch.
oudhury, Handbook of Michrolithography, Michroma
chining and Michrofabrication, Volume 2: Michromach
ining and Michrofabrication, P495, Fig.8.58, SPIE PR
Published by ESS and Optics Communication, Volume 140 (1997) P187〜
Like the membrane mirror described in 190, when a voltage is applied between the plurality of electrodes 409b, the thin film 409a is deformed by electrostatic force and its surface shape is changed. This allows not only focus adjustment according to the diopter of the observer but also the lens 90
1, 902 and / or prism 404, isosceles right-angle prism 405, mirror 406 due to deformation or change in refractive index due to temperature or humidity change, or due to expansion or contraction or deformation of lens frame and assembly error of components such as optical element or frame. The deterioration of the imaging performance can be suppressed, and the focus adjustment and the aberration caused by the focus adjustment can always be properly corrected. The shape of the electrode 409b is, for example, as shown in FIGS.
You can select it according to how to transform.

According to the present embodiment, the light from the object is refracted by the incident surface and the exit surface of the objective lens 902 and the prism 404, reflected by the deformable mirror 409, and the prism 40.
4, is further reflected by the isosceles right-angled prism 405 (in FIG. 10, the + sign in the optical path indicates that the light beam advances toward the back side of the paper surface), and is reflected by the mirror 406. The light enters the eye through the eyepiece lens 901. In this way, the lenses 901 and 902, the prisms 404 and 405, and the deformable mirror 409 constitute an observation optical system of the optical device of the present embodiment.
By optimizing the surface shape and the wall thickness of each of these optical elements, the aberration of the object plane can be minimized.

That is, the shape of the thin film 409a as the reflecting surface is controlled by changing the resistance value of each variable resistor 411 by a signal from the arithmetic unit 414 so that the imaging performance is optimized. That is, the arithmetic unit 414
To the temperature sensor 415, the humidity sensor 416, and the distance sensor 417, a signal having a size corresponding to the ambient temperature and humidity and the distance to the object is input to the arithmetic unit 414.
In order to compensate for the deterioration of the imaging performance due to the ambient temperature and humidity conditions and the distance to the object based on these input signals,
A voltage that determines the shape of the thin film 409a is applied to the electrode 40.
A signal for determining the resistance value of the variable resistor 411 is output so as to be applied to 9b. Thus, the thin film 409
Since a is deformed by the voltage applied to the electrode 409b, that is, electrostatic force, its shape can be various shapes including an aspherical surface depending on the situation, and can be made a convex surface by changing the polarity of the applied voltage. Note that the distance sensor 417 may be omitted, and in that case, the image pickup lens 403 of the digital camera is moved so that the high frequency component of the image signal from the solid-state image pickup element 408 is substantially maximum, and the object distance is reversed from that position. Is calculated, and the deformable mirror is deformed to bring the observer's eye into focus.

If the thin film 409a is made of a synthetic resin such as polyimide, it is convenient because it can be greatly deformed even at a low voltage. The prism 404 and the deformable mirror 409 can be integrally formed into a unit.

Although not shown, the deformable mirror 40 is also shown.
The solid-state image sensor 408 may be integrally formed on the substrate No. 9 by a lithographic process.

Further, the lenses 901 and 902 and the prism 4
By forming the 04, 405 and the mirror 406 with a plastic mold or the like, a curved surface of any desired shape can be arbitrarily formed, and the manufacturing is also easy. In the image pickup apparatus of this embodiment, the lenses 901 and 902 are the prism 4
The lenses 901 and 90 are formed apart from 04.
The prisms 404 and 405, the mirror 406, and the deformable mirror 4 so that the aberration can be removed without providing 2.
If 09 is designed, the prisms 404 and 405 and the deformable mirror 409 become one optical block, which facilitates assembly. Further, the lenses 901 and 902 and the prisms 404 and 4
05, part or all of the mirror 406 may be made of glass, and if configured in this way, an image pickup device with higher accuracy can be obtained.

In the example of FIG. 10, the arithmetic unit 414,
Although the temperature sensor 415, the humidity sensor 416, and the distance sensor 417 are provided so that changes in temperature and humidity, changes in the object distance, and the like are compensated by the deformable mirror 409, this need not be the case. That is, the arithmetic unit 414 and the temperature sensor 41
5, omit the humidity sensor 416, distance sensor 417,
Only the change in the diopter of the observer may be corrected by the deformable mirror 409.

FIG. 11 is a schematic diagram showing another embodiment of the deformable mirror 409 applicable to the variable mirror used in the optical pickup of the present invention. Deformable mirror 409 of the present embodiment
Is the piezoelectric element 40 between the thin film 409a and the electrode 409b.
9c is interposed, and these are provided on the support base 423. Then, by changing the voltage applied to the piezoelectric element 409c for each electrode 409b, the piezoelectric element 409c
The shape of the thin film 409a can be changed by partially expanding and contracting c. Electrode 40
The shape of 9b may be concentric division as shown in FIG. 12, or may be rectangular division as shown in FIG. 13, and any other appropriate shape can be selected.
In FIG. 11, reference numeral 424 denotes a shake (blur) sensor connected to the arithmetic unit 414, which detects the shake of, for example, a digital camera and deforms the thin film 409a so as to compensate the image disturbance due to the shake. The voltage applied to the electrode 409b via 414 and the variable resistor 411 is changed. At this time, signals from the temperature sensor 415, the humidity sensor 416, and the distance sensor 417 are also taken into consideration at the same time, and focusing, temperature and humidity compensation, etc. are performed. In this case, since stress is applied to the thin film 409a due to the deformation of the piezoelectric element 409c, it is preferable that the thin film 409a be made thicker to some extent to have a corresponding strength.

FIG. 14 is a schematic configuration diagram showing still another embodiment of the deformable mirror 409 applicable to the variable mirror used in the optical pickup of the present invention. In the deformable mirror of this embodiment, the piezoelectric element interposed between the thin film 409a and the electrode 409b is composed of two piezoelectric elements 409c and 409c 'made of a material having piezoelectric characteristics in opposite directions. In terms of
This is different from the deformable mirror of the embodiment shown in FIG. That is, if the piezoelectric elements 409c and 409c 'are made of a ferroelectric crystal, the crystal axes are arranged so as to be opposite to each other. In this case, the piezoelectric elements 409c and 409
Since c ′ expands and contracts in the opposite direction when a voltage is applied, the force for deforming the thin film 409a becomes stronger than in the case of the embodiment shown in FIG. 11, and as a result the shape of the mirror surface can be greatly changed. There is an advantage.

Examples of materials used for the piezoelectric elements 409c and 409c 'are barium titanate, Rossier salt,
Quartz crystals, tourmaline, potassium dihydrogen phosphate (KDP), ammonium dihydrogen phosphate (ADP), piezoelectric materials such as lithium niobate, polycrystals of the same, crystals of the same, PbZ
There are piezoelectric ceramics of solid solution of rO ₃ and PbTiO ₃ , organic piezoelectric materials such as polyvinyl difluoride (PVDF), and ferroelectric materials other than the above. In particular, organic piezoelectric materials have a small Young's modulus and undergo large deformation even at low voltage. Is possible, which is preferable. When using these piezoelectric elements, if the thickness is made nonuniform, the shape of the thin film 409a can be appropriately deformed in the above embodiment.

As the material of the piezoelectric elements 409c and 409c ', polyurethane, silicon rubber, acrylic elastomer, PZT, PLZT, high molecular piezoelectric material such as polyvinylidene fluoride (PVDF), vinylidene cyanide copolymer, vinylidene fluoride, etc. A copolymer of ride and trifluoroethylene is used. If an organic material having piezoelectricity, a synthetic resin having piezoelectricity, an elastomer having piezoelectricity, or the like is used, a large deformation of the deformable mirror surface may be realized.

When an electrostrictive material such as acrylic elastomer or silicon rubber is used for the piezoelectric element 409c shown in FIGS. 11 and 15, the piezoelectric element 409c is provided on another substrate 4.
09c-1 and electrostrictive material 409c-2 may be bonded together.

FIG. 15 is a schematic configuration diagram showing still another embodiment of the deformable mirror 409 applicable to the variable mirror used in the optical pickup of the present invention. In the deformable mirror of this embodiment, the piezoelectric element 409c is sandwiched between the thin film 409a and the electrode 409d, and the voltage is applied between the thin film 409a and the electrode 409d via the drive circuit 425 controlled by the arithmetic unit 414. Further, separately from this, a voltage is applied to the electrode 409b provided on the support base 423 through the drive circuit 425 controlled by the arithmetic unit 414. Therefore, in this embodiment, the thin film 409a can be doubly deformed by the voltage applied between the electrode 409d and the electrostatic force generated by the voltage applied to the electrode 409b. Even more deformation patterns are possible,
Moreover, there is an advantage that the responsiveness is fast.

By changing the sign of the voltage between the thin film 409a and the electrode 409d, the deformable mirror can be deformed into a convex surface or a concave surface. In that case, a large deformation may be performed by the piezoelectric effect and a minute shape change may be performed by the electrostatic force. Further, the piezoelectric effect may be mainly used for the deformation of the convex surface, and the electrostatic force may be mainly used for the deformation of the concave surface. The electrode 4
09d may be composed of a plurality of electrodes like the electrode 409b. This state is shown in FIG. In the present application, the piezoelectric effect, the electrostrictive effect, and the electrostrictive are all referred to as the piezoelectric effect. Therefore, the electrostrictive material is also included in the piezoelectric material.

FIG. 16 is a schematic configuration diagram showing still another embodiment of the deformable mirror 409 applicable to the variable mirror used in the optical pickup of the present invention. The deformable mirror of this embodiment is configured such that the shape of the reflecting surface can be changed by utilizing electromagnetic force. A permanent magnet 426 is provided on the inner bottom surface of the support 423 and silicon nitride is provided on the top surface. Alternatively, the peripheral portion of the substrate 409e made of polyimide or the like is placed and fixed,
A thin film 409a made of a metal coating such as aluminum is attached to the surface of the substrate 409e.
09 is configured. A plurality of coils 427 are arranged on the lower surface of the substrate 409e, and each of these coils 427 is connected to the arithmetic unit 414 via a drive circuit 428. Therefore, each sensor 415, 416,
An arithmetic unit 414 corresponding to the change of the optical system obtained by the arithmetic unit 414 by the signals from 417 and 424.
When an appropriate current is supplied to each coil 427 from each drive circuit 428 by the output signal from each coil 427, each coil 427 is repelled or attracted by the electromagnetic force working with the permanent magnet 426, and the substrate 409e and the thin film 409a. Transform.

In this case, each coil 427 can be made to flow a different amount of current. Further, the number of the coils 427 may be one, or the permanent magnet 426 may be provided on the substrate 40.
9e may be attached and the coil 427 may be provided on the inner bottom surface side of the support base 423. The coil 427 may be formed by a method such as lithography, and the coil 42
An iron core made of a ferromagnetic material may be inserted in 7.

In this case, the winding density of the thin film coil 427 is
As shown in FIG. 17, it is possible to give desired deformation to the substrate 409e and the thin film 409a by changing the position. Further, the number of the coils 427 may be one, or an iron core made of a ferromagnetic material may be inserted into these coils 427.

FIG. 18 is a schematic configuration diagram showing still another embodiment of the deformable mirror 409 applicable to the variable mirror used in the optical pickup of the present invention. In the deformable mirror of this embodiment, the substrate 409e is made of a ferromagnetic material such as iron,
The thin film 409a as a reflection film is made of aluminum or the like. In this case, since it is not necessary to provide the thin film coil, the structure is simple and the manufacturing cost can be reduced. If the power switch 413 is replaced with a switch for switching and opening / closing the power, the direction of the current flowing through the coil 427 can be changed, and the shapes of the substrate 409e and the thin film 409a can be freely changed. FIG. 19 shows the arrangement of the coil 427 in this embodiment, and FIG.
7 shows other examples of arrangements, but these arrangements are shown in FIG.
It can also be applied to the embodiment shown in FIG. Note that, in FIG. 21, the coil 427 in the embodiment shown in FIG.
20 shows an arrangement of the permanent magnets 426 suitable when the arrangement of is set as shown in FIG. That is, if the permanent magnets 426 are radially arranged as shown in FIG.
Subtle modifications can be applied to the substrate 409e and the thin film 409a as compared with the embodiment shown in FIG. Further, in the case of deforming the substrate 409e and the thin film 409a by using the electromagnetic force (the embodiment of FIGS. 16 and 18) as described above, there is an advantage that the voltage can be driven at a lower voltage than in the case of using the electrostatic force.

Although some examples of the deformable mirror applicable to the variable mirror used in the optical pickup of the present invention have been described above, in order to change the shape of the mirror, as shown in the example of FIG. You may use two or more types of force. That is, electrostatic force, electromagnetic force, piezoelectric effect, magnetostriction, fluid pressure, electric field,
The deformable mirror may be deformed by simultaneously using two or more of the magnetic field, the temperature change, the electromagnetic wave and the like. That is, if the variable optical characteristic element is manufactured by using two or more different driving methods, a large deformation and a minute deformation can be realized at the same time, and an accurate mirror surface can be realized.

FIG. 22 is an image pickup system using a deformable mirror 409 applicable to a variable mirror used in the optical pickup of the present invention, for example, a digital camera of a mobile phone, a capsule endoscope, an electronic endoscope, a digital camera for a personal computer. FIG. 1 is a schematic configuration diagram of an image pickup system used in a PDA digital camera or the like. In the image pickup system of this embodiment, the deformable mirror 409, the lens 902, the solid-state image pickup device 408, and the control system 103 constitute one image pickup unit 104. In the image pickup unit 104 of the present embodiment, the light from the object that has passed through the lens 102 is condensed by the deformable mirror 409, and the solid-state image pickup element 40
Image on top of 8. The deformable mirror 409 is a kind of variable-optical-characteristic optical element, and is also called a variable-focus mirror.

According to this embodiment, even if the object distance changes, the deformable mirror 409 can be deformed for focusing, and it is not necessary to drive the lens by a motor or the like, and the size and weight can be reduced. Excellent in low power consumption.
The image pickup unit 104 can be used in all the embodiments as the image pickup system of the present invention. In addition, the deformable mirror 4
By using a plurality of 09, it is possible to create an image pickup system and optical system for zooming and zooming. In FIG. 22, the control system 103
The example of the configuration of the control system including the step-up circuit of the transformer using the coil is shown in FIG. In particular, it is possible to reduce the size by using a laminated piezoelectric transformer. The booster circuit can be used for all the variable-shape mirrors and variable-focus lenses using electricity of the present invention, but is particularly useful for variable-shape mirrors and variable-focus lenses when electrostatic force or piezoelectric effect is used.

FIG. 23 is a schematic configuration diagram of a deformable mirror 188 according to still another embodiment applicable to the variable mirror used in the optical pickup of the present invention, in which the fluid 161 is taken in and out by the micropump 180 and the lens surface is deformed. Is. According to this embodiment, there is an advantage that the lens surface can be largely deformed. Micro pump 180
Is a small pump made by, for example, micromachine technology, and is configured to operate on electric power. Fluid 161
Are sandwiched between the transparent substrate 163 and the elastic body 164. Examples of pumps made by micromachine technology include those that utilize thermal deformation, those that use piezoelectric materials,
There are some that use electrostatic force.

FIG. 24 is a schematic diagram showing an embodiment of a micropump used in a deformable mirror applicable to the variable mirror used in the optical pickup of the present invention. In the micropump 180 of this embodiment, the vibration plate 181 vibrates due to an electrostatic force, an electric force such as a piezoelectric effect, or the like. FIG. 24 shows an example of vibration due to electrostatic force.
83 is an electrode. Also, the dotted line is the vibration plate 1 when deformed.
81 is shown. With the vibration of the vibration plate 181, the two valves 184 and 185 are opened and closed to send the fluid 161 from right to left.

In the deformable mirror 188 of this embodiment, the reflecting film 189 functions as a deformable mirror by being deformed into unevenness in accordance with the amount of the fluid 161. Deformable mirror 188 is driven by fluid 161. As the fluid, organic substances such as silicone oil, air, water, jelly, etc., and inorganic substances can be used.

A variable voltage mirror or variable focus lens using electrostatic force or piezoelectric effect may require a high voltage for driving. In that case, for example, FIG.
As shown in, the control system may be configured using a boosting transformer, a piezoelectric transformer, or the like. Further, if the thin film 409a for reflection is provided also in a portion which is not deformed, it is convenient because it can be used as a reference surface when the shape of the deformable mirror is measured by an interferometer or the like.

FIG. 25 is a diagram showing the structure of an example of a variable focus mirror applicable to the variable mirror used in the optical pickup of the present invention. The variable focus mirror 565 shown in FIG. 25 is configured using a variable focus lens. Therefore, the variable focus lens will be described before the description of the variable focus mirror 565.

FIG. 26 is a diagram showing the principle of the variable focus lens. The varifocal lens 511 has the first and second
Having lens surfaces 508a and 508b as surfaces of the first
Lens 512a, and a second lens 512b having lens surfaces 509a and 509b as third and fourth surfaces,
It has a polymer dispersed liquid crystal layer 514 provided between these lenses via transparent electrodes 513a and 513b, and converges incident light through the first and second lenses 512a and 512b. The transparent electrodes 513a and 513b are connected to an AC power source 516 via a switch 515 so that an AC electric field is selectively applied to the polymer dispersed liquid crystal layer 514. The polymer-dispersed liquid crystal layer 514 includes a large number of minute polymer cells 518 each having a spherical shape, a polyhedron shape, or the like, each containing liquid crystal molecules 517, and the volume thereof constitutes the polymer cell 518. Polymers and liquid crystal molecules 517
Match the sum of the volume occupied by each.

Here, when the size of the polymer cell 518 is, for example, spherical, its average diameter D is, for example, 2 nm ≦ D ≦ λ / 5 (where the wavelength of the light used is λ). 1) That is, the size of the liquid crystal molecule 517 is 2 nm.
The average diameter D has a lower limit of 2 nm.
That is all. Further, the upper limit of D is the variable focus lens 51.
1, the thickness t of the polymer dispersed liquid crystal layer 514 in the optical axis direction
If it is larger than λ, the difference between the refractive index of the polymer and the refractive index of the liquid crystal molecules 517 causes the polymer cell 5 to have a large difference.
Since light is scattered at the boundary surface of 18 and the polymer dispersed liquid crystal layer 514 becomes opaque, it is preferably λ / 5 or less as described later. High precision may not be required depending on the optical product in which the variable focus lens is used, and then D may be λ or less. The transparency of the polymer dispersed liquid crystal layer 514 becomes worse as the thickness t increases.

As the liquid crystal molecules 517, for example, uniaxial nematic liquid crystal molecules are used. This liquid crystal molecule 517
The refractive index ellipsoid has a shape as shown in FIG. 27, where n _ox = n _oy = n _o (2). However, n _o is the refractive index of an ordinary ray, n _ox and n _oy are refractive indices in directions perpendicular to each other in a plane including an ordinary ray.

Here, as shown in FIG. 26, the switch 5
When 15 is turned off, that is, when the electric field is not applied to the polymer dispersed liquid crystal layer 514, the liquid crystal molecules 517 are oriented in various directions.
Has a high refractive index and has a strong refractive power. On the other hand, as shown in FIG. 28, when the switch 515 is turned on and an AC electric field is applied to the polymer-dispersed liquid crystal layer 514, the liquid crystal molecules 517 have a major axis direction of the index ellipsoid that is the optical axis of the variable focus lens 511. Since it is oriented so as to be parallel to, the refractive index becomes low and the lens has a weak refractive power.

The voltage applied to the polymer dispersed liquid crystal layer 514 is, for example, as shown in FIG.
It can also be changed stepwise or continuously by 9. By doing this, as the applied voltage increases,
The liquid crystal molecules 517 are oriented so that their elliptical long axes gradually become parallel to the optical axis of the varifocal lens 511, so that the refractive power can be changed stepwise or continuously.

Here, the average refractive index n _LC 'of the liquid crystal molecules 517 in the state shown in FIG. 26, that is, in the state where no electric field is applied to the polymer dispersed liquid crystal layer 514, is as shown in FIG. If the refractive index in the major axis direction of is n _z , then approximately (n _ox + n _oy + n _z ) / 3≡n _LC ′ (3). Further, the (2) the average refractive index n _LC when the expression is satisfied, it represents a n _z the refractive index n _e of the extraordinary ray is given by _{(2n o + n e) /} 3≡n LC ... (4) . At this time, the refractive index n _A of the polymer dispersed liquid crystal layer 514 is the ratio of the volume of the liquid crystal molecules 517 to the volume of the polymer dispersed liquid crystal layer 514, where n _P is the refractive index of the polymer constituting the polymer cell 518. the When ff, the law of Maxwell Garnett, given by _{n a = ff · n LC '} + (1-ff) n P ... (5).

Therefore, as shown in FIG. 29, assuming that the radii of curvature of the inner surfaces of the lenses 512a and 512b, that is, the surfaces on the polymer dispersed liquid crystal layer 514 side are R ₁ and R ₂ , respectively, the varifocal lens 511 has Focal length f
₁ is given by _{1 / f 1 = (n A} -1) (1 / R 1 -1 / R 2) ... (6). Note that R ₁ and R ₂ are positive when the center of curvature is on the image point side. Further, refraction by the outer surfaces of the lenses 512a and 512b is excluded. That is,
The focal length of the lens formed only by the polymer dispersed liquid crystal layer 514 is given by the equation (6).

If the average refractive index of the ordinary ray is (n _ox + n _oy ) / 2 = n _o ′ (7), the state shown in FIG. 28, that is, an electric field is applied to the polymer dispersed liquid crystal layer 514. and in state, the refractive index n _B of the polymer dispersed liquid crystal layer _{514, n B = ff · n o} '+ (1-ff) because it is given by n _P ... (8), in this case the polymer dispersed liquid crystal Layer 514
The focal length f ₂ of the lens due to only is given by 1 / f ₂ = (n _B −1) (1 / R ₁ −1 / R ₂ ) ... (9). The polymer-dispersed liquid crystal layer 514 has a structure shown in FIG.
The focal length when a voltage lower than that in 8 is applied is a value between the focal length f ₁ given by the equation (6) and the focal length f ₂ given by the equation (9).

From the above equations (6) and (9), the change rate of the focal length due to the polymer dispersed liquid crystal layer 514 is | (f ₂ −f ₁ ) / f ₂ | = | (n _B −n _A ) / (N _B -1) | ... (10) Therefore, to increase this rate of change, it is sufficient to increase | n _B −n _A |. Since n _B −n _A = ff (n _o ′ −n _LC ′) (11), the rate of change can be increased by increasing | n _o ′ −n _LC ′ |. In practice, n _B is
Since it is about 1.3 to 2, if 0.01 ≦ | n _o ′ −n _LC ′ | ≦ 10 (12), when ff = 0.5, the polymer dispersed liquid crystal layer 51 is obtained.
Since the focal length of 4 can be changed by 0.5% or more, an effective variable focus lens can be obtained. In addition, | n _o '-n _LC ' |
Can't be exceeded.

Next, the basis of the upper limit value of the above equation (1) will be described. `` Solar Energy Materials and Solar Cell
s '' Volume 31, Wilson and Eck, 1993, Eleevier Science Publ
Ishers B.v., pages 197-214, `` Transmission var
iation using scattering / transparent switching film
"s" shows the change in the transmittance τ when the size of the polymer-dispersed liquid crystal was changed. On page 206 of this document, FIG. 6, the radius of the polymer dispersed liquid crystal is r,
t = 300 μm, ff = 0.5, n _P = 1.45, n _LC
= 1.585 and λ = 500 nm, the transmittance τ
Is a theoretical value, r = 5 nm (D = λ / 50, D · t = λ
When τ is 6 μm (however, the units of D and λ are nm, the same applies below), τ≈90%, and r = 25 nm (D = λ
It is shown that τ≈50% when / 10).

Here, for example, when t = 150 μm is estimated, assuming that the transmittance τ changes by an exponential function of t, the transmittance τ when t = 150 μm is estimated. , R = 25 nm (D = λ / 10, D · t = λ · 1
5 μm), τ≈71%. Also, t = 75 μm
In the case of, similarly, r = 25 nm (D = λ / 10, D ·
When t = λ · 7.5 μm), τ≈80%.

From these results, if D · t ≦ λ · 15 μm (13), then τ becomes 70% to 80% or more, which is sufficiently practical as a lens. Therefore, for example, t = 75 μm
In the case of, D ≦ λ / 5, and a sufficient transmittance can be obtained.

The transmittance of the polymer-dispersed liquid crystal layer 514 is improved as the value of n _P is closer to the value of n _LC ′. on the other hand,
When the n _o 'and n _P are different values, polymer dispersed liquid crystal layer 5
The transmittance of 14 becomes worse. In the state of FIG. 26 and the state of FIG. 28, the average transmittance of the polymer dispersed liquid crystal layer 514 is improved by satisfying n _P = (n _o '+ n _LC ') / 2 (14) It's time.

Here, since the variable focus lens 511 is used as a lens, it is preferable that the transmittance is substantially the same and high in both the state of FIG. 26 and the state of FIG. For that purpose, there are restrictions on the polymer material constituting the polymer cell 518 and the material of the liquid crystal molecules 517, but practically, it is sufficient to set n _o ′ ≦ n _P ≦ n _LC ′ (15). .

If the above equation (14) is satisfied, the above equation (13) becomes
It is further relaxed, and it is sufficient if D · t ≦ λ · 60 μm (16). This is because, according to Fresnel's reflection law, the reflectance is proportional to the square of the difference in the refractive index, so that the reflection of light at the boundary between the polymer that constitutes the polymer cell 518 and the liquid crystal molecule 517, that is, polymer dispersion. The decrease of the transmittance of the liquid crystal layer 514 is caused by the above-mentioned polymer and liquid crystal molecule 517.
This is because it is proportional to the square of the difference between the refractive indexes of and.

The above is n _o ′ ≈1.45, n _LC ′ ≈1.
585 was the case, if more Generally formulated, D · t ≦ λ · 15μm · (1.585-1.45) 2 / (n u -n P) 2 ... (17) Good. However, (n _u −n _P ) ² is (n _LC '−
It is the larger of n _P ) ² and ( _no'- n _P ) ² .

Further, in order to make the change in the focal length of the variable focus lens 511 large, it is preferable that the value of ff be large, but f
When f = 1, the volume of the polymer becomes zero, and the polymer cell 5
Since 18 cannot be formed, 0.1 ≦ ff ≦ 0.999 (18). On the other hand, as ff decreases, τ improves, so
The equation (17) is preferably a 4 × 10 ^-6 [μm] ^{2 ≦ D · t ≦ λ ·} 45μm · (1.585-1.45) 2 / (n u -n P) 2 ... (19). Note that the lower limit value of t is t = D, as is clear from FIG. 26, and since D is 2 nm or more as described above, the lower limit value of D · t is (2 × 10 ⁻³ μm). ² , that is, 4 × 10 ⁻⁶ [μm] ² .

The approximation of the optical property of a material by the refractive index is established as described in “Iwanami Science Library 8 Asteroids are Coming”, Tadashi Mukai, 1994, page 58, published by Iwanami Shoten. , D is larger than 10 nm to 5 nm. Further, when D exceeds 500λ, the light scattering becomes geometrical, and the light scattering at the interface between the polymer constituting the polymer cell 518 and the liquid crystal molecule 517 increases according to the Fresnel reflection formula. Is practically set to 7 nm ≦ D ≦ 500λ (20).

FIG. 30 shows the variable focus lens 5 shown in FIG.
11 shows a configuration of an image pickup optical system for a digital camera using 11. In this image pickup optical system, an image of an object (not shown) is formed on a solid-state image pickup device 523 such as a CCD through a diaphragm 521, a variable focus lens 511 and a lens 522. Note that illustration of liquid crystal molecules is omitted in FIG.

According to such an image pickup optical system, the variable resistor 5
19, the polymer dispersed liquid crystal layer 5 of the variable focus lens 511.
The variable focus lens 5 is adjusted by adjusting the AC voltage applied to the lens 14.
By changing the focal length of 11, the variable focus lens 51
For example, it is possible to continuously focus on an object distance from infinity to 600 mm without moving 1 and the lens 522 in the optical axis direction.

FIG. 31 is a view showing the arrangement of an example of a variable focus diffractive optical element using the principle of a variable focus lens. The variable focus diffractive optical element 531 includes a first transparent substrate 532 having parallel first and second surfaces 532a and 532b,
A second transparent substrate 533 having a third surface 533a formed with a ring-shaped diffraction grating having a sawtooth cross section and a flat fourth surface 533b having a groove depth on the order of the wavelength of light is provided. The light is emitted through the first and second transparent substrates 532 and 533. First and second transparent substrate 53
26, the polymer-dispersed liquid crystal layer 514 is interposed between the transparent electrode 513a and the transparent electrode 513 through the transparent electrodes 513a and 513b.
And the transparent electrodes 513a and 513b are connected to the switch 515.
And connected to an AC power supply 516 through the polymer dispersed liquid crystal layer 5
An alternating electric field is applied to 14.

In such a structure, the light beam incident on the variable focus diffractive optical element 531 is deflected by an angle θ satisfying psin θ = mλ (21) where p is the grating pitch of the third surface 533a and m is an integer. Is emitted. When the groove depth is h, the refractive index of the transparent substrate 33 is n _33, and k is an integer, h (n _A −n ₃₃ ) = mλ (22) h (n _B −n ₃₃ ) = kλ If (23) is satisfied, the diffraction efficiency becomes 100% at the wavelength λ, and flare can be prevented from occurring.

Here, when the difference between both sides of the above equations (22) and (23) is obtained, h (n _A −n _B ) = (m−k) λ (24) is obtained. Therefore, for example, λ = 500 nm, n
_A = 1.55, when _{n B = 1.5, 0.05h = (} m-k) · 500nm next, when m = 1, k = 0, the h = 10000nm = 10μm. In this case, the refractive index n ₃₃ of the transparent substrate 533 may be n ₃₃ = 1.5 from the above formula (22). In addition, the grating pitch p in the peripheral portion of the variable focus diffractive optical element 531
Is 10 μm, θ≈2.87 °, and a lens with an F number of 10 can be obtained.

Since the optical path length of the variable focus diffractive optical element 531 varies depending on whether the voltage applied to the polymer dispersed liquid crystal layer 514 is turned on or off, the variable focus diffractive optical element 531 is arranged, for example, in a portion where the light flux of the lens system is not parallel to adjust the focus. Can be used to change the focal length of the entire lens system.

In this embodiment, (22)-
Equation (24) is, in practice, 0.7 mλ ≦ h (n _A −n ₃₃ ) ≦ 1.4 mλ (25) 0.7 kλ ≦ h (n _B −n ₃₃ ) ≦ 1.4 kλ (26) 0 .7 (m−k) λ ≦ h (n _A −n _B ) ≦ 1.4 (m−k) λ (27)

There is also a variable focus lens that uses twisted nematic liquid crystals. 32 and 33 show the configuration of the varifocal glasses 550 in this case. The varifocal lens 551 includes lenses 552 and 553, and transparent electrodes 513a, 51 on the inner surfaces of these lenses, respectively.
3b, and the twisted nematic liquid crystal layer 554 provided between the alignment films 539a and 539b.
The transparent electrodes 513a and 513b are connected to the AC power source 516 through the variable resistor 519 so that an AC electric field is applied to the twisted nematic liquid crystal layer 554.

In such a structure, when the voltage applied to the twisted nematic liquid crystal layer 554 is increased, the liquid crystal molecules 555 are homeotropically aligned as shown in FIG. 33, and in the case of the twisted nematic state where the applied voltage is low as shown in FIG. In comparison, twisted nematic liquid crystal layer 5
The refractive index of 54 becomes small and the focal length becomes long.

Here, since the helical pitch P of the liquid crystal molecules 555 in the twisted nematic state shown in FIG. 32 needs to be equal to or sufficiently smaller than the wavelength λ of light, for example, 2 nm ≦ P ≦ 2λ / 3. … (28) Note that the lower limit of this condition is determined by the size of the liquid crystal molecules, and the upper limit is when the incident light is natural light.
Is a value necessary for the twisted nematic liquid crystal layer 554 to behave as an isotropic medium in the above condition, and if the condition of this upper limit value is not satisfied, the varifocal lens 551 becomes a lens having a different focal length depending on the polarization direction. A double image is formed and only a blurred image can be obtained.

FIG. 34 (a) shows the structure of a variable deflection angle prism to which the principle of the variable focus lens is applied. The variable deflection angle prism 561 includes the first and second surfaces 562a and 562a,
It has a first transparent substrate 562 on the incident side having 62b and a second transparent substrate 563 having a parallel plate shape on the emitting side having third and fourth surfaces 563a and 563b. An inner surface (second surface) 562b of the incident side transparent substrate 562 is formed in a Fresnel shape, and the transparent substrate 562 and the emission side transparent substrate 5 are formed.
63 between the transparent electrode 5 and the transparent electrode 5 as in FIG.
A polymer dispersed liquid crystal layer 514 is provided via 13a and 513b. The transparent electrodes 513a and 513b are connected to the variable resistor 51.
9 to connect to an AC power supply 516, thereby applying an AC electric field to the polymer-dispersed liquid crystal layer 514 to control the deviation angle of light passing through the variable deviation angle prism 561. Although the inner surface 562b of the transparent substrate 562 is formed in a Fresnel shape in FIG. 34 (a), for example, as shown in FIG. 34 (b), the inner surfaces of the transparent substrates 562 and 563 are inclined relative to each other. It may be formed in a normal prism shape having a surface, or may be formed in the diffraction grating shape shown in FIG. When forming in the shape of a diffraction grating,
The above equations (21) to (27) similarly apply.

The variable deflection angle prism 561 having the above structure is
For example, it can be effectively used for preventing blurring of TV cameras, digital cameras, film cameras, binoculars and the like. In this case, the refraction direction (deflection direction) of the variable deflection angle prism 561 is preferably the vertical direction. However, in order to further improve the performance, the two variable deflection angle prisms 561 have different deflection directions. For example, as shown in FIG. 35, it is desirable to arrange them so that the refraction angle is changed in the vertical direction and the horizontal direction. Note that FIG. 34 and FIG.
In FIG. 5, illustration of liquid crystal molecules is omitted.

Then, the variable focus mirror 56 shown in FIG.
5 also applies the principle of the variable focus lens. The varifocal mirror 565 has the first and second surfaces 566a, 5
It has a first transparent substrate 566 having 66b and a second transparent substrate 567 having third and fourth surfaces 567a and 567b. The first transparent substrate 566 is formed in a flat plate shape or a lens shape, and the transparent electrode 513a is provided on the inner surface (second surface) 566b, and the second transparent substrate 567 is formed on the inner surface (third surface).
Surface 567a is formed in a concave shape, a reflecting film 568 is applied on the concave surface, and the transparent electrode 5 is formed on the reflecting film 568.
13b is provided. Between the transparent electrodes 513a and 513b,
As described in FIG. 26, the polymer dispersed liquid crystal layer 514 is provided, and these transparent electrodes 513a and 513b are connected to the switch 5
An AC electric field is applied to the polymer dispersed liquid crystal layer 514 by connecting to the AC power supply 516 via the variable resistor 15 and the variable resistor 519. Note that the liquid crystal molecules are not shown in FIG.

According to this structure, a light ray incident from the transparent substrate 566 side serves as an optical path that folds back the polymer dispersed liquid crystal layer 514 by means of the reflection film 568, so that the polymer dispersed liquid crystal layer 514 can function twice. At the same time, by changing the voltage applied to the polymer dispersed liquid crystal layer 514,
The focal position of reflected light can be changed. In this case, the light beam incident on the varifocal mirror 565 is transmitted through the polymer dispersed liquid crystal layer 514 twice, so that the polymer dispersed liquid crystal layer 514 is transmitted.
Each of the above equations can be similarly used, where t is twice the thickness of the above. Note that the inner surface of the transparent substrate 566 or 567 may be formed into a diffraction grating shape as shown in FIG. 31 to reduce the thickness of the polymer dispersed liquid crystal layer 514. This has the advantage that the scattered light can be reduced.

In the above description, in order to prevent deterioration of the liquid crystal, the AC power supply 516 is used as the power supply to apply the AC electric field to the liquid crystal. However, the DC power supply is used to apply the DC electric field to the liquid crystal. You can also choose to do so. As a method of changing the direction of the liquid crystal molecules, other than changing the voltage, changing the frequency of the electric field applied to the liquid crystal, the strength / frequency of the magnetic field applied to the liquid crystal, the temperature of the liquid crystal, or the like may be used. In the configuration example shown above, the polymer-dispersed liquid crystal is not liquid but may be close to solid. Therefore, in that case, one of the lenses 512a and 512b, the transparent substrate 532, the lens 538, and the lenses 552 and 5 are used.
53, one of the transparent substrate 563 in FIG.
One of the transparent substrates 562 and 563 and one of the transparent substrates 566 and 567 in 4 (b) may be omitted. Note that, in the present application, a variable focus mirror whose shape does not change as shown in FIG. 25 is also included in the variable shape mirror.

FIG. 36 is a schematic diagram showing still another embodiment of the deformable mirror applicable to the variable mirror used in the optical pickup of the present invention. In the present embodiment, it will be described as being used in a digital camera. In addition, in FIG.
411 is a variable resistor, 414 is an arithmetic unit, 415 is a temperature sensor, 416 is a humidity sensor, 417 is a distance sensor, and 424 is a shake sensor. The deformable mirror 45 of the present embodiment is provided with a divided electrode 409b with an electrostrictive material 453 made of an organic material such as an acrylic elastomer, and the like.
An electrode 452 and a deformable substrate 451 are sequentially provided on the electrostrictive material 453, and a reflective film 450 made of a metal such as aluminum that reflects incident light is further provided thereon. According to this structure, the reflective film 450 is different from the case where the divided electrode 409b is integrated with the electrostrictive material 453.
Has a merit that the surface shape is smooth and it is difficult to optically generate aberration. The deformable substrate 4
The arrangement of 51 and the electrode 452 may be reversed. In addition, FIG.
Reference numeral 449 denotes a button for zooming or zooming the optical system, and the deformable mirror 45 deforms the shape of the reflection film 450 when the user presses the button 449 to zoom or zoom. It is controlled via the arithmetic unit 414 so that it can be performed. Note that the piezoelectric material such as barium titanate described above may be used in place of the electrostrictive material formed of an organic material such as acrylic elastomer.

Finally, the definitions of terms used in the present invention will be described.

The optical device is a device including an optical system or an optical device. The optical device alone may not function. That is, it may be a part of the device.

The optical device includes an image pickup device, an observation device, a display device, a lighting device, a signal processing device and the like.

As an example of the image pickup device, a film camera,
There are digital cameras, robot eyes, interchangeable-lens digital single-lens reflex cameras, television cameras, video recording devices, electronic video recording devices, camcorders, VTR cameras, electronic endoscopes, and the like. Digital camera, card type digital camera, TV camera,
Both the VTR camera and the moving image recording camera are examples of electronic image pickup devices.

Examples of the observation device include a microscope, a telescope,
There are eyeglasses, binoculars, loupes, fiberscopes, viewfinders, viewfinders, and the like.

Examples of the display device include a liquid crystal display, a viewfinder, a game machine (PlayStation manufactured by Sony Corporation), a video projector, a liquid crystal projector, and a head mounted image display device (head mo).
There are an undisplayed display (HMD), a PDA (personal digital assistant), a mobile phone, and the like.

Examples of the illumination device include a strobe of a camera, a headlight of a car, an endoscope light source, a microscope light source, and the like.

Examples of the signal processing device include a mobile phone, a personal computer, a game machine, an optical disk reading / writing device,
There is an arithmetic unit for an optical computer.

The image pickup device is, for example, a CCD, an image pickup tube, a solid-state image pickup device, a photographic film, or the like. The plane-parallel plate is included in one of the prisms. Changes in the observer include changes in diopter. To change the subject,
It includes changes in the distance to an object, movement of the object, movement of the object, vibration, blurring of the object, and the like.

The definition of the extended curved surface is as follows. In addition to spheres, planes, and rotationally symmetric aspherical surfaces, spherical surfaces decentered with respect to the optical axis, planes, rotationally symmetric aspherical surfaces, aspherical surfaces having a symmetric surface, aspherical surfaces having only one symmetric surface, and non-symmetrical non-spherical surfaces. It may have any shape such as a spherical surface, a free-form surface, a non-differentiable point, or a surface having a line. It may be a reflecting surface or a refracting surface as long as it can affect light in some way. In the present invention, these are collectively referred to as an extended curved surface.

The variable optical characteristic optical element includes a variable focus lens, a variable mirror, a polarizing prism having a changed surface shape, a variable apex angle prism, and a variable diffractive optical element having a different light deflection action, that is, a variable HOE, a variable DOE and the like.

The variable focus lens includes a variable lens whose focal length does not change and whose amount of aberration changes. The same applies to the variable mirror. In short, an optical element that can change the light deflection action such as reflection, refraction, and diffraction of light is called an optical characteristic variable optical element.

The information transmitting device is a remote controller such as a mobile phone, a fixed type telephone, a game machine, a television, a radio-cassette player, a stereo, a personal computer, a personal computer keyboard, a mouse,
This refers to a device that can input and send some information such as a touch panel. It also includes a TV monitor with an imaging device, a personal computer monitor, and a display. The information transmission device is included in the signal processing device.

As described above, the optical pickup of the present invention has the following features in addition to the description of the claims.

(1) The optical pickup according to claim 1 or 2, wherein the variable mirror has a mirror surface whose shape changes to a flat surface or a concave surface and a convex surface having a curved surface shape.

(2) The optical pickup according to claim 1 or 2, wherein the variable mirror has a mirror surface whose shape changes to a flat surface or a concave surface having a curvature surface shape.

(3) The optical pickup according to claim 1 or 2, wherein the variable mirror has a mirror surface whose shape changes to a flat surface or a convex surface having a curvature surface shape.

(4) The optical system according to claim 2, wherein the variable mirror corrects spherical aberration caused by a substrate thickness error of the recording medium by changing the shape of the mirror surface. pick up.

(5) The optical pickup according to claim 2, wherein the variable mirror corrects a coma aberration caused by an inclination and a warp of the recording medium by changing the shape of the mirror surface. .

(6) The variable mirror corrects spherical aberration caused by a substrate thickness error of the recording medium and coma aberration caused by warp by changing the shape of the mirror surface. The optical pickup according to claim 2.

(7) The variable mirror is formed of a piezoelectric material having a plurality of divided electrodes, and any one of the above (1) to (6). The optical pickup described in Crab.

(8) The variable mirror has a permanent magnet or a coil arranged near the optical surface and a member capable of flowing a current integrated with the optical surface, and has a surface shape by an electromagnetic force. The optical pickup according to any one of claims 1 and 2, and (1) to (6), wherein the optical pickup is changed.

(9) The variable mirror has a variable shape optical element which has the same structure and can be commonly used for a plurality of optical devices. (7) or (8) Optical pickup.

(10) The variable mirror is electrically controlled, and (1) to (1) to (1) above.
The optical pickup according to any one of (9).

(11) The variable mirror is driven by static electricity, and (1) above.
An optical pickup according to any one of (9) to (9).

(12) The optical pickup according to any one of (1) to (9) above, wherein the variable mirror is driven by an electromagnetic force.

(13) The optical pickup according to any one of (1) to (9) above, wherein the variable mirror is driven by a piezoelectric effect or electrostriction.

[0109]

According to the present invention, it is possible to provide an optical pickup which consumes less power, produces a quiet sound, has a short response time, has a simple mechanical structure, and contributes to cost reduction.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an optical pickup according to the present invention.

2A and 2B are graphs showing spherical aberration of an objective lens for recording media having different substrate thicknesses in an optical pickup, and FIG. 2A is a spherical aberration for recording media having a substrate thickness of 0.6 mm, and FIG. b) shows spherical aberration for a recording medium having a substrate thickness of 1.2 mm.

3A to 3D are explanatory views showing a deformed state of a mirror surface of a variable mirror in the optical pickup of the present embodiment.

4A to 4C are explanatory diagrams showing states of light focused on a recording medium when a mirror surface of a variable mirror in the optical pickup of the present embodiment is deformed.

FIG. 5 is a graph showing the difference signal of the detector with respect to the amount of change in the shape of the mirror surface of the variable mirror in the optical pickup of the present embodiment.

FIG. 6 is a schematic configuration diagram showing a modified example of the optical pickup of the present embodiment.

7 (a) to 7 (c) are explanatory diagrams showing states of light focused on a recording medium when the mirror surface of the variable mirror in the optical pickup of the modified example of FIG. 6 is deformed.

FIG. 8 is a schematic configuration diagram showing another modification of the optical pickup of the present embodiment.

9A to 9C are explanatory diagrams showing states of light condensed on the recording medium when the mirror surface of the variable mirror in the optical pickup of the modified example of FIG. 8 is deformed.

FIG. 10 is a schematic configuration diagram of a Kepler-type finder of a digital camera using a deformable mirror applicable to a variable mirror used in the optical pickup of the present invention.

FIG. 11 is a schematic configuration diagram showing another embodiment of the deformable mirror 409 applicable to the variable mirror used in the optical pickup of the present invention.

FIG. 12 is an explanatory diagram showing one form of electrodes used in the deformable mirror of the embodiment of FIG.

FIG. 13 is an explanatory diagram showing another form of an electrode used in the deformable mirror of the embodiment of FIG.

FIG. 14 is a schematic configuration diagram showing still another embodiment of the deformable mirror 409 applicable to the variable mirror used in the optical pickup of the present invention.

FIG. 15 is a schematic configuration diagram showing still another embodiment of the deformable mirror 409 applicable to the variable mirror used in the optical pickup of the present invention.

FIG. 16 is a schematic configuration diagram showing still another embodiment of the deformable mirror 409 applicable to the variable mirror used in the optical pickup of the present invention.

FIG. 17 is an explanatory diagram showing a winding density state of the thin film coil 427 in the embodiment of FIG.

FIG. 18 is a schematic configuration diagram showing still another embodiment of the deformable mirror 409 applicable to the variable mirror used in the optical pickup of the present invention.

FIG. 19 is an explanatory diagram showing one arrangement example of the coil 427 in the embodiment of FIG.

20 is an explanatory diagram showing another arrangement example of the coil 427 in the embodiment of FIG.

FIG. 21 is a circuit diagram of the coil 42 in the embodiment shown in FIG.
It is explanatory drawing which shows the arrangement | positioning of the permanent magnet 426 suitable when the arrangement of 7 is set as shown in FIG.

FIG. 22 is an image pickup system using a deformable mirror 409 applicable to a variable mirror used in the optical pickup of the present invention, for example, a mobile phone digital camera, a capsule endoscope, an electronic endoscope, a personal computer digital camera, and a PDA. FIG. 2 is a schematic configuration diagram of an image pickup system used for a digital camera for use in mobile phones.

FIG. 23 is a schematic configuration diagram of a deformable mirror 188 according to still another embodiment applicable to the variable mirror used in the optical pickup of the present invention, in which the fluid 161 is taken in and out by the micro pump 180, and the lens surface is deformed. .

FIG. 24 is a schematic configuration diagram showing an example of a micropump used for a deformable mirror applicable to the variable mirror used for the optical pickup of the present invention.

FIG. 25 is a diagram showing an example of the configuration of a variable focus mirror applicable to the variable mirror used in the optical pickup of the present invention.

FIG. 26 is a diagram showing a principle configuration of a variable focus lens.

FIG. 27 is a diagram showing an index ellipsoid of a uniaxial nematic liquid crystal molecule.

28 is a diagram showing a state in which an electric field is applied to the polymer dispersed liquid crystal layer shown in FIG.

29 is a diagram showing an example of a configuration in which the voltage applied to the polymer-dispersed liquid crystal layer shown in FIG. 26 is variable.

30 is a diagram showing an example of an image pickup optical system for a digital camera using the variable focus lens 511 shown in FIG.

FIG. 31 is a diagram showing a configuration of an example of a variable focus diffractive optical element using the principle of a variable focus lens.

FIG. 32 is a diagram showing a configuration of variable-focus eyeglasses having a variable-focus lens that uses twisted nematic liquid crystal.

33 is a diagram showing the alignment state of liquid crystal molecules when the voltage applied to the twisted nematic liquid crystal layer shown in FIG. 32 is increased.

FIG. 34 is a diagram showing the configurations of two examples of variable deflection angle prisms to which the principle of the variable focus lens is applied.

FIG. 35 is a diagram for explaining how to use the variable deflection angle prism shown in FIG. 34.

FIG. 36 is a schematic configuration diagram showing still another embodiment of the deformable mirror applicable to the variable mirror used in the optical pickup of the present invention.

FIG. 37 is a schematic configuration diagram showing a conventional example of an optical pickup.

[Explanation of symbols]

1,1 'Optical pickup 2 Light source 3 Collimator lens 4 Polarization beam splitter 5 Wave plate 6 Variable mirror 6', 406 Mirror 7,902 Objective lens 8 Recording medium 9 Collimator lens 10 Photodetector 45,188 Variable shape mirror 102,512a , 512b, 522, 538
Lens 103 Control system 104 Imaging unit 160,180 Micro pump 161 Fluid 163,532,533,562,563,566,5
67 Transparent substrate 164 Elastic body 168 Liquid reservoir 181 Vibrating plates 182, 183, 409b, 409d, 452
Electrodes 184, 185 Valves 189, 450 Reflective film 426 Permanent magnet 404 Prism 409c-2 Electrostrictive material 403 Imaging lens 405 Isosceles right angle prisms 408, 523 Solid-state imaging device 409 Optical characteristic variable shape mirror (variable mirror member) 409a Thin film (reflection) Surface) 409c, 409c 'Piezoelectric element 409c-1, 409e, 706 Substrate 411 Variable resistor 412 Power supply 413 Power switch 414 Arithmetic device 415 Temperature sensor 416 Humidity sensor 417 Distance sensor 423 Support stand 424 Shake sensor 425, 428 Drive circuit 427 Coil 449 button 451 deformable substrate 453 electrostrictive material 509a, 533a, 563a, 567a third surface 509b, 533b, 563b, 567b fourth surface 511 variable focus lens 513a, 513b, 610 transparent electrode 5 4 polymer dispersed liquid crystal layer 515 switch 516 AC power supply 517 liquid crystal molecule 518 polymer cell 519 variable resistor 521 diaphragm 531 variable focus diffractive optical element 532a, 562a, 566a first surface 532b, 562b, 566b second surface 539a, 539b Alignment film 550 Variable focus glasses 561 Variable deflection angle prism 565 Variable focus mirror 568 Reflective film 901 Eyepiece

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5D118 AA08 AA23 AA26 BA01 CD02                       DC02 DC07 EA01 EA07 EA11                 5D119 AA11 AA21 AA37 AA41 BA01                       EA03 EC01 EC04 JA09 JA57                 5D789 AA11 AA21 AA37 AA41 BA01                       EA03 EC01 EC04 JA09 JA57

Claims (2)

[Claims] 1. In an optical pickup of an optical recording / reproducing apparatus, which has at least a light source, an objective lens, and a reflection mirror that bends laser light from the light source by 90 degrees and irradiates the objective lens, the reflection mirror has a different shape. An optical pickup comprising a variable mirror having a mirror surface for changing the shape of the mirror surface and a surface shape changing means for changing the shape of the mirror surface. 2. An optical pickup of an optical recording / reproducing apparatus having at least a light source, an objective lens, a reflection mirror for bending a laser beam from the light source 90 degrees and irradiating the objective lens, and a recording medium. A recording medium having different substrate thicknesses by changing the shape of the mirror surface, which is composed of a variable mirror having a mirror surface whose shape changes and a surface shape changing means for changing the shape of the mirror surface. An optical pickup characterized in that the laser light can be focused so as to be able to input and output.