Variable mirror and information apparatus comprising variable mirror

• US 6,952,304 B2
• Filed: 01/29/2002
• Issued: 10/04/2005
• Est. Priority Date: 01/30/2001
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Takizawa, Teruyuki, Mushika, Yoshihiro
• Primary Examiner(s): Spector, David N.
• Application Number:
  US10/470,685
• Publication Number:
  US 20040061917A1
• Time in Patent Office: 1,344 Days
• Field of Search: 359/291, 359/295, 359/846, 359/847, 359/853, 369/44.23, 369/112.01
• US Class Current: 359/295
• CPC Class Codes: G02B 26/06 for controlling the phase of light G02B26/08 takes precedence , measuring optical phase difference G01J9/00
• CPC Class Codes: G02B 26/0825 the reflecting element being a flexible sheet or membrane, e.g. for varying the focus flexible mirrors for cosmetic use A45D42/24
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 3/0043 Inhomogeneous or irregular arrays, e.g. varying shape, size, height
• CPC Class Codes: G02B 3/005 arranged along a single direction only, e.g. lenticular sheets G02B3/0043 takes precedence
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085
• CPC Class Codes: G02B 3/0068 arranged in a single integral body or plate, e.g. laminates or hybrid structures with other optical elements G02B5/1885, G02B17/002, G02B30/27 take precedence
• CPC Class Codes: G11B 2007/0006 adapted for scanning different types of carrier, e.g. CD & DVD
• CPC Class Codes: G11B 7/124 the integrated head arrangements including waveguides
• CPC Class Codes: G11B 7/131 Arrangement of detectors in a multiple array
• CPC Class Codes: G11B 7/1362 Mirrors
• CPC Class Codes: G11B 7/13927 during transducing, e.g. to correct for variation of the spherical aberration due to disc tilt or irregularities in the cover layer thickness

Abstract

A deformable mirror according to the invention comprises a substrate, a reflector which is supported by said substrate and the shape of whose reflecting areas is variable, and a plurality of drive units for independently driving a plurality of regions of the reflector and thereby controlling the distances between said plurality of regions and said substrate. Each of the plurality of drive units comprises a plurality of electrodes disposed over said substrate, a tilt member which is rotated round the axis of tilt by being attracted by the selected one of the plurality of electrodes, and an action member for varying the distance between a specific region of the reflector and said substrate following the motion of the tilt member.

Claims

1. A deformable mirror comprising:

a substrate;

a reflector supported by said substrate and having a plurality of light reflecting areas which can be separately driven; and

a plurality of drive units for independently driving each of said plurality of light reflecting areas and thereby controlling the dispositional relationship between each light reflecting area and said substrate, wherein;

each of said plurality of drive units comprises;

a plurality of electrodes supported by said substrate,

a tilt member which is tiltable around the axis of tilt by being attracted by a selected one of said plurality of electrodes, and

a coupling member for coupling the tilt member with the reflector at a distance from the axis of tilt.

2. The deformable mirror according to claim 1 wherein said coupling member changes the distance between the light reflecting area and the substrate according to the movement of the tilt member.

3. The deformable mirror according to claim 1 wherein:

said tilt member has a supporting portion arranged on said axis of tilt and a planar portion coupled to said supporting portion,

said planar portion of said tilt member includes a first electroconductive portion and a second electroconductive portion which are symmetric with respect to said axis of tilt, and

said plurality of electrodes include a first electrode opposite the first electroconductive portion of said planar portion with a gap in-between and a second electrode opposite the second electroconductive portion of said planar portion with a gap in-between.

4. The deformable mirror according to claim 3 wherein each light reflecting area of said reflector is coupled to one of the first electroconductive member and the second electroconductive member of said planar portion in the corresponding one of said drive units via said coupling member.

5. The deformable mirror according to claim 4 wherein, in a selected drive unit out said plurality of drive units, the curvature of the surface of said light reflecting area coupled to said drive unit can be varied by performing an action to make either one of the spacing between said first electroconductive portion of said planar portion and said first electrode and the spacing between said second electroconductive portion of said planar portion and said second electrode shorter than the other.

6. The deformable mirror according to claim 5 wherein said action is executed by providing a higher electric potential to either one of said first electrode and said second electrode in said selected drive unit than to the other.

7. The deformable mirror according to claim 1 wherein the circumference of said reflector is configured of a deformable film fixed to said substrate, and

said film comprises tension in advance.

8. The deformable mirror according to claim 7 wherein said reflective film is formed of a material having a greater thermal expansion coefficient than the thermal expansion coefficient of said substrate, and

said reflective film has been formed at a higher temperature than the temperature at which it is intended to be used.

9. The deformable mirror according to claim 8 wherein said coupling member is a portion protruding from said film and formed of the same material as the material of said film.

10. The deformable mirror according to claim 9 wherein the distance between said coupling member and the axis of tilt in each drive unit is set as a function of the position of said drive unit on said substrate.

11. The deformable mirror according to claim 7 wherein said reflector is fixed to said substrate at a fixed point position farther inside than the circumference thereof.

12. The deformable mirror according to claim 7 wherein, out of said plurality of drive units, a drive unit arranged in position relatively close to said fixed point has the distance between the corresponding coupling member and the axis of tilt being set shorter than those of drive units arranged relatively far from said fixed point.

13. The deformable mirror according to claim 1 wherein said reflector is configured of a plurality of micromirrors separated from one another, and

said plurality of micromirrors are coupled to respectively different drive units out of said plurality of drive units and are independently displaceable.

14. The deformable mirror according to claim 13 wherein, when no drive signal is given to said drive units, the reflective surfaces of said micromirrors are arrayed on a virtual same plane where the curvature becomes substantially zero, and

when any drive signal is given to said drive units, said reflective surface is displaced forward or backward relative to said plane.

15. The deformable mirror according to claim 13 wherein said micromirrors have a shape whose lengthwise direction is a direction parallel to said axis of tilt, and

said drive units have a shape whose lengthwise direction is a direction normal to said axis of tilt.

16. The deformable mirror according to claim 1 further comprising a voltage applying circuit which receives an address signal to designate a selected drive unit out of said plurality of drive units and a drive signal to be given to said drive unit designated by said address signal, and

applies voltages to said electrodes in said selected drive unit on the basis of said address signal and said drive signal.

17. The deformable mirror according to claim 16 wherein said voltage applying circuit comprises:

an address counter which updates n (n is an integer not smaller than

     2) output values in a circulatory process with a first clock signal,

a counter which updates output values with a second clock signal generated by dividing the frequency of the first clock by n,

a memory for outputting drive signals according to the output of said address counter,

a comparator for comparing the output of said memory and the output of said counter,

a shift register for shifting the output of said comparator in response to the first clock signal, and

a latch unit for latching the output of said shift register in response to said second clock signal.

18. An information device for irradiating a medium with forward light emitted from a light source and detecting information stored by said medium on the basis of backward light modulated by said medium, said information device comprising:

a wave front detector for detecting the wave fronts of said backward light in respect of each of a plurality of detection regions included in a section across the optical axis of said backward light,

a wave front corrector, provided within the optical path of said forward light and/or backward light, for locally varying the optical path length of said forward light and/or backward light by an action of a plurality of drive units arrayed on a plane crossing said optical path, and

a control unit for supplying a plurality of drive signals to said wave front corrector on the basis of a plurality of outputs of said wave front detector and reconstructing the whole wave fronts of said backward light wherein;

said wave front corrector comprises a deformable mirror according to claim 1.

19. An optical compensation device comprising:

a deformable mirror according to claim 1; and

an optical detector for receiving light beams reflected by said deformable mirror and modulated by the medium, wherein;

said deformable mirror and said optical detector are integrated over the same substrate.

20. An information device comprising an optical compensation device according to claim 19.