Holographic recording and reproducing apparatus

• US 20050078342A1
• Filed: 08/20/2004
• Published: 04/14/2005
• Est. Priority Date: 08/27/2003
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Tsukagoshi, Takuya, Yoshinari, Jiro
• Granted Patent: US 6,961,161 B2
• Time in Patent Office: Days
• US Class Current: 359/10
• CPC Class Codes: G03H 1/2249 Holobject properties
• CPC Class Codes: G03H 2210/20 2D object
• CPC Class Codes: G11B 7/0065 Recording, reproducing or erasing by using optical interference patterns, e.g. holograms

Abstract

An image detected by a CCD image sensor 108 when only a non-modulated signal light is applied to a holographic memory 120 in which data is not recorded is ensured as a noise pattern. When data is reproduced, the previously obtained noise pattern is subtracted from a reproduced image detected by the CCD image sensor 108.

Claims

1. A holographic recording and reproducing apparatus in which a signal light and a reference light are applied to a holographic memory to record data as the interference pattern of the light and the data is reproduced from a reproduced image obtained by applying the reference light to the holographic memory;

the holographic recording and reproducing apparatus comprising;

a noise pattern detecting unit for detecting a noise pattern in a prescribed page of the holographic memory;

a noise pattern storage unit for storing the noise pattern;

a data reproducing unit for reading the reproduced image from the prescribed page of the holographic memory; and

a noise removing unit for removing a noise component from the reproduced image by using the noise pattern previously detected by the noise pattern detecting unit.

2. A holographic recording and reproducing apparatus according to claim 1, wherein the noise pattern storage unit includes an external storage device for storing data therein.

3. A holographic recording and reproducing apparatus according to claim 1, wherein the noise pattern storage unit includes a noise pattern recording unit for recording the noise pattern on the holographic memory.

4. A holographic recording and reproducing apparatus according to claim 1, wherein the noise pattern detecting unit includes:

a signal light applying unit for applying the non-modulated signal light to the prescribed page of the holographic memory;

a light receiving unit for receiving the signal light that passes through or is reflected on the holographic memory; and

a noise pattern processing unit for compressing the noise pattern from the light receiving unit.

5. A holographic recording and reproducing apparatus according to claim 4, wherein the noise pattern storage unit includes a noise pattern recording unit for recording the noise pattern on the holographic memory.

6. A holographic recording and reproducing apparatus according to claim 1, wherein the noise pattern recording unit records the noise pattern detected in each page of the holographic memory in the page together with data to be originally recorded.

7. A holographic recording and reproducing apparatus according to claim 1, wherein the noise pattern recording unit concentrically records the noise pattern detected in each page of the holographic memory in a prescribed area of the holographic memory separately from the data to be originally recorded.

8. A holographic recording and reproducing apparatus, according to claim 1, wherein the noise pattern detecting unit detects the noise pattern by a gray scale.

9. A holographic recording and reproducing apparatus according to claim 1, wherein when the noise pattern detecting unit sequentially detects the noise patterns respectively in the pages of the holographic memory, the noise pattern detecting unit detects the noise patterns at intervals of prescribed pages.

10. A holographic recording and reproducing apparatus according to claim 9, wherein when the data reproducing unit reproduces data on a page in which the noise pattern is not recorded, the data reproducing unit removes a noise component from the reproduced image by using a noise pattern obtained by performing an interpolating process using the noise patterns of the pages before and after the page.

11. A holographic recording and reproducing apparatus according to claim 10, wherein when a plurality of data is recorded in the same place by a phase code multiplex recording or a wavelength multiplex recording, the noise removing unit removes the noise component from the reproduced image by using a noise pattern common to each of the data.