Inline type speckle multiplexed hologram recording apparatus and inline type speckle multiplexed hologram recording method

• US 20050243389A1
• Filed: 04/01/2005
• Published: 11/03/2005
• Est. Priority Date: 04/05/2004
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kihara, Nobuhiro
• Granted Patent: US 7,362,482 B2
• Time in Patent Office: Days
• US Class Current: 359/9
• CPC Class Codes: G03H 1/0404 In-line recording arrangement
• CPC Class Codes: G03H 1/12 Spatial modulation, e.g. ghost imaging
• CPC Class Codes: G03H 2223/14 Diffuser, e.g. lens array, random phase mask
• 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 7/128 Modulators G11B7/1245 takes precedence
• CPC Class Codes: G11B 7/1392 Means for controlling the beam wavefront, e.g. for correction of aberration optical systems for aberration correction per se G02B27/00

Abstract

An inline type speckle multiplexed hologram recording apparatus and method is disclosed which can condense signal light and reference light in a sufficiently overlapping relationship with each other on a hologram recording medium without using a lens having a large aperture and a wide angle of view. A signal light region and a reference light region are displayed on a spatial light modulator, and laser light is intensity modulated with recording data displayed in the signal light region to produce signal light while the laser light having passed through the reference light region is used as reference light. The signal light and the reference light are diffused by a diffuser and then condensed in an overlapping relationship with each other on a hologram recording medium by a lens such that interference fringes produced thereby are recorded in the hologram recording medium.

Claims

1. An inline type speckle multiplexed hologram recording apparatus which produces signal light and reference light from coherent light and illuminates the signal light and the reference light from the same direction on a hologram recording medium to record interference fringes of the signal light and the reference light in the hologram recording medium, comprising:

a spatial light modulator for spatially modulating the coherent light; and

a display control section for displaying a reference light region to be used to produce the reference light from the coherent light introduced into said spatial light modulator and a signal light region to be used to produce the signal light intensity modulated with data at the same time on said spatial light modulator.

2. An inline type speckle multiplexed hologram recording apparatus according to claim 1, further comprising a diffusion member for diffusing both of the signal light and the reference light produced or only the reference light.

3. An inline type speckle multiplexed hologram recording apparatus according to claim 2, wherein said diffusion member diffuses the signal light and the reference light with different degrees of diffusion from each other.

4. An inline type speckle multiplexed hologram recording apparatus according to claim 2, wherein said diffusion member is disposed closely in front of or in the rear of said spatial light modulator.

5. An inline type speckle multiplexed hologram recording apparatus according to claim 2, wherein said diffusion member is projected on said spatial light modulator.

6. An inline type speckle multiplexed hologram recording apparatus according to claim 1, wherein said display control section displays a plurality of reference light regions in a distributed relationship in said signal light region.

7. An inline type speckle multiplexed hologram recording apparatus according to claim 1, wherein said reference light region serves also as a display section for positioning of reproduction data to be displayed on said spatial light modulator.

8. An inline type speckle multiplexed hologram recording apparatus according to claim 7, wherein a plurality of such display sections for positioning are displayed around and/or inside said signal light region.

9. An inline type speckle multiplexed hologram recording apparatus according to claim 2, wherein the hologram recording medium is displaced by a small distance to record data in a multiplexed state.

10. An inline type speckle multiplexed hologram recording apparatus according to claim 2, wherein said display control section displays a pattern in said reference light region of said spatial light modulator and varies the pattern to vary a speckle pattern of the reference light to record data in a multiplexed state.

11. An inline type speckle multiplexed hologram recording apparatus according to claim 1, wherein said display control section displays said signal light region and said reference light region with luminance values of different from each other on said spatial light modulator.

12. An inline type speckle multiplexed hologram recording apparatus according to claim 11, wherein said display control section controls said spatial light modulator such that pixels which pass light therethrough in said signal light region and pixels which pass light therethrough in said reference light region are different from each other.

13. A hologram recording method wherein signal light and reference light are produced from coherent light and illuminated from the same direction on a hologram recording medium to record interference fringes of the signal light and the reference light in the hologram recording medium, wherein:

light emitted from a portion of a spatial light modulator which spatially modulates the coherent light to produce the signal light is used as the reference light.

14. A hologram recording method according to claim 13, wherein light emitted from a plurality of positioning marks upon reproduction of the spatial light modulator is used as the reference light, and the positioning marks are distributed on a displaying face of the spatial light modulator such that the signal light and the reference light sufficiently overlap with each other in the hologram recording medium.

15. An inline type speckle multiplexed hologram method, comprising the steps of:

displaying a signal light region and a reference light region on a spatial light modulator;

intensity modulating coherent light with recording data displayed in the signal light region and diffusing the intensity modulated light by means of a diffusion member to produce signal light;

diffusing the light passing through the reference light region by means of the diffusion member to produce reference light; and

recording interference fringes produced by condensing the diffused signal light and the diffused reference light in an overlapping relationship with each other on a hologram recording medium into the hologram recording medium.