LIGHT DEFLECTING DEVICE AND HOLOGRAM DEVICE

• US 20100027086A1
• Filed: 11/01/2006
• Published: 02/04/2010
• Est. Priority Date: 11/01/2006
• Status: Active Grant

• Current Assignee: Pioneer Corporation
• Original Assignee: Pioneer Corporation
• Inventors: Sato, Makoto, Ogasawara, Masakazu
• Granted Patent: US 8,189,252 B2
• Time in Patent Office: Days
• US Class Current: 359/22
• CPC Class Codes: G02B 26/08 for controlling the direction of light in light guides G02B6/35
• CPC Class Codes: G03H 1/265 Angle multiplexing; Multichannel holograms G03H1/268 takes precedence
• CPC Class Codes: G03H 1/28 superimposed holograms only
• CPC Class Codes: G11B 7/0065 Recording, reproducing or erasing by using optical interference patterns, e.g. holograms
• CPC Class Codes: G11B 7/00772 on record carriers storing information in the form of optical interference patterns, e.g. holograms
• CPC Class Codes: G11B 7/08564 using galvanomirrors
• CPC Class Codes: G11B 7/133 Shape of individual detector elements
• CPC Class Codes: G11B 7/1369 Active plates, e.g. liquid crystal panels or electrostrictive elements

Abstract

A light deflecting device is a light deflecting device for deflecting an incident light beam and has: a coarse motion light deflecting device which has an optical system having at least two conjugate points on an optical axis and deflects the light beam which has passed through one conjugate point and has entered the optical system as an output light beam which passes through the other conjugate point and has a deflection angle with respect to the optical axis while changing its transmitting direction; and a fine motion light deflecting device which is arranged in the optical system, applies a deflection to the incident light beam, and changes the deflection angle of the output light beam to a second deflection angle different from the deflection angle for a predetermined time.

Claims

1. A light deflecting device for deflecting an incident light beam, comprising:

a coarse motion light deflecting device which has an optical system and deflects the light beam which has passed through one conjugate point and has entered the optical system as an output light beam which passes through another conjugate point and has a deflection angle from an optical axis while changing a transmitting direction of the incident light beam; and

a fine motion light deflecting device which is arranged in the optical system to apply a deflection to the light beam entered thereinto so as to change the deflection angle of the output light beam into a second deflection angle which is different from the deflection angle for a predetermined time;

an input side photodetector for guiding a part of the light beam which does not pass through the fine motion light deflecting device in the coarse motion light deflecting device and calculating a light input side signal which changes according to an angle of the light beam for the optical axis;

an output side photodetector for guiding a part of the light beam after it passed through the fine motion light deflecting device and calculating a light output side signal which changes according to the angle of the light beam for the optical axis; and

a driving circuit for controlling a voltage which is applied to the fine motion light deflecting device on the basis of the light input side signal and the light output side signal, thereby changing the deflection angle for a progressing change in a stairway manner.

2. The light deflecting device according to claim 1, wherein the fine motion light deflecting device applies the deflection adapted to counterbalance a progressing change of the deflection angle of the output light beam so as to set the output light beam into a rest state for the predetermined time.

3. The light deflecting device according to claim 1, wherein a galvano mirror is arranged at one of the conjugate points and the conjugate point is located on a rotary axis of the galvano mirror.

4. The light deflecting device according to claim 1, wherein the fine motion light deflecting device is a liquid crystal deflecting element.

5. The light deflecting device according to claim 1, wherein the liquid crystal deflecting element is arranged at the conjugate point of the optical system of the coarse motion light deflecting device.

7. The light deflecting device according to claim 1, wherein the input side photodetector has a strip-shaped photosensing element.

8. The light deflecting device according to claim 1, wherein the output side photodetector has a strip-shaped photosensing element.

9. The light deflecting device according to claim 1, wherein the applied voltage to the fine motion light deflecting device is controlled so that the light output side signal is set to a predetermined value and, when a change in sign of the light input side signal is detected, the applied voltage is reset to an initial value.

10. The light deflecting device according to claim 1, wherein the optical system has at least two conjugate points on the optical axis.

6. (canceled)

11. A hologram device for recording or reproducing information to/from a hologram recording medium in which an optical interference pattern of reference light and signal light is held as a diffraction grating, comprising:

a light forming section for forming the reference light and the signal light obtained by modulating coherence light according to the recording information from the coherence light;

an interfering section for mutually spatially separating an optical path of the reference light and an optical path of the signal light and allowing one of the optical paths to intersect the other one, thereby allowing the reference light and the signal light to be interfered;

a supporting portion for detachably supporting the hologram recording medium to an intersection point of the optical paths of the reference light and the signal light;

an image detecting section for receiving light diffracted from the diffraction grating of the hologram recording medium when the reference light has been irradiated to the hologram recording medium; and

a light deflecting device for deflecting a light beam of the reference light,

wherein the light deflecting device includes

a coarse motion light deflecting device which has an optical system and deflects the light beam of the reference light which has passed through the conjugate point on an input side and has entered the optical system toward the conjugate point on an output side which coincides with the intersection point from angle directions of mutually different deflection angles from the optical axis while changing a transmitting direction of the incident light beam,

a fine motion light deflecting device which is arranged in the optical system, applies a deflection adapted to counterbalance a change in the transmitting direction to the light beam of the reference light so as to set the light beam of the reference light into a rest state for a predetermined time, and

a driving circuit for controlling so as to select the angle direction of the light beam of the reference light when the information is recorded or reproduced to/from the coarse motion light deflecting device and the fine motion light deflecting device,

the light deflecting device further comprising;

an input side photodetector for guiding a part of the light beam which does not pass through the fine motion light deflecting device in the coarse motion light deflecting device and calculating a light input side signal which changes according to an angle of the light beam for the optical axis; and

an output side photodetector for guiding a part of the light beam after it passed through the fine motion light deflecting device and calculating a light output side signal which changes according to the angle of the light beam for the optical axis;

wherein the driving circuit controls a voltage which is applied to the fine motion light deflecting device on the basis of the light input side signal and the light output side signal, thereby changing the deflection angle for a progressing change in a stairway manner.