Apparatus and method for recording optical information, apparatus and method for reproducing optical information, and apparatus and method for recording/reproducing optical information

• US 20040100892A1
• Filed: 01/02/2003
• Published: 05/27/2004
• Est. Priority Date: 07/05/2000
• Status: Active Grant

• Current Assignee: Optware Corporation
• Original Assignee: Optware Corporation
• Inventors: Horimai, Hideyoshi
• Granted Patent: US 7,065,032 B2
• Time in Patent Office: Days
• US Class Current: 369/103
• CPC Class Codes: G03H 1/04 Processes or apparatus for producing holograms G03H1/26 takes precedence
• CPC Class Codes: G03H 1/22 Processes or apparatus for obtaining an optical image from holograms G03H1/26 - G03H1/34 take precedence
• CPC Class Codes: G03H 2210/12 Phase modulating object, e.g. living cell
• CPC Class Codes: G03H 2210/22 2D SLM object wherein the object beam is formed of the light modulated by the SLM SLM per se G03H2001/0224
• CPC Class Codes: G03H 2223/19 Microoptic array, e.g. lens array
• CPC Class Codes: G11B 7/0065 Recording, reproducing or erasing by using optical interference patterns, e.g. holograms
• CPC Class Codes: G11B 7/00781 Auxiliary information, e.g. index marks, address marks, pre-pits, gray codes
• CPC Class Codes: G11B 7/123 Integrated head arrangements, e.g. with source and detectors mounted on the same substrate
• CPC Class Codes: G11B 7/128 Modulators G11B7/1245 takes precedence
• CPC Class Codes: G11B 7/1356 Double or multiple prisms, i.e. having two or more prisms in cooperation

Abstract

It is an object of the invention to record or reproduce information through the use of holography, attain a small configuration of the optical system for recording or reproduction, and improve the S/N ratio of reproduced information.

For recording information, a phase spatial light modulator (44) generates information light that is spatially modulated in phase based on information to be recorded, and recording-specific reference light, to irradiate an information recording layer (3) of an optical information recording medium (1) with the same so that the information is recorded on the information recording layer (3) in the form of an interference pattern resulting from interference between the information light and the recording-specific reference light. For reproducing the information, the information recording layer (3) is irradiated with reproduction-specific reference light, and then reproduction light thereby generated from the information recording layer (3) is superimposed on the reproduction-specific reference light to generate composite light. This composite light is detected by a photodetector (45) to reproduce the information.

Claims

1. An optical information recording apparatus for recording information on an optical information recording medium having an information recording layer in which information is recorded through the use of holography, the apparatus comprising:

information light generating means for generating information light by spatially modulating a phase of light based on information to be recorded;

recording-specific reference light generating means for generating recording-specific reference light; and

a recording optical system for irradiating the information recording layer with the information light generated by the information light generating means and the recording-specific reference light generated by the recording-specific reference light generating means so that the information is recorded in the information recording layer in the form of an interference pattern resulting from interference between the information light and the recording-specific reference light.

2. An optical information recording apparatus according to claim 1, wherein the recording optical system performs the irradiation with the information light and the recording-specific reference light on the same side of the information recording layer so that the information light and the recording-specific reference light are arranged coaxially.

3. An optical information recording apparatus according to claim 1, wherein the information light generating means sets the phase of the light after the modulation at either of two values.

4. An optical information recording apparatus according to claim 1, wherein the information light generating means sets the phase of the light after the modulation at any of three or more values.

5. An optical information recording apparatus according to claim 1, wherein the recording-specific reference light generating means generates the recording-specific reference light that is spatially modulated in phase.

6. An optical information recording apparatus according to claim 5, wherein the information light generating means spatially modulates the phase of the light in accordance with a phase modulation pattern determined based on the information to be recorded and a phase modulation pattern of the recording-specific reference light.

7. An optical information recording apparatus according to claim 1, further comprising a flying-type head body that accommodates the information light generating means, the recording-specific reference light generating means and the recording optical system, and flies over the optical information recording medium.

8. An optical information recording method for recording information on an optical information recording medium having an information recording layer in which information is recorded through the use of holography, the method comprising:

the step of generating information light by spatially modulating a phase of light based on information to be recorded;

the step of generating recording-specific reference light; and

the recording step in which the information recording layer is irradiated with the information light and the recording-specific reference light so that the information is recorded on the information recording layer in the form of an interference pattern resulting from interference between the information light and the recording-specific reference light.

9. An optical information recording method according to claim 8, wherein, in the recording step, the irradiation with the information light and the recording-specific reference light is performed on the same side of the information recording layer so that the information light and the recording-specific reference light are arranged coaxially.

10. An optical information recording method according to claim 8, wherein, in the step of generating the information light, the phase of the light after the modulation is set at either of two values.

11. An optical information recording method according to claim 8, wherein, in the step of generating the information light, the phase of the light after the modulation is set at any of three or more values.

12. An optical information recording method according to claim 8, wherein the step of generating the recording-specific reference light generates the recording-specific reference light that is spatially modulated in phase.

13. An optical information recording method according to claim 12, wherein, in the step of generating the information light, the phase of the light is spatially modulated in accordance with a phase modulation pattern determined based on the information to be recorded and a phase modulation pattern of the recording-specific reference light.

14. An optical information reproducing apparatus for reproducing information through the use of holography from an optical information recording medium having an information recording layer in which information is recorded in the form of an interference pattern resulting from interference between information light that is spatially modulated in phase based on information to be recorded, and recording-specific reference light, the apparatus comprising:

reproduction-specific reference light generating means for generating reproduction-specific reference light;

a reproducing optical system for irradiating the information recording layer with the reproduction-specific reference light generated by the reproduction-specific reference light generating means, collecting reproduction light that is generated from the information recording layer irradiated with the reproduction-specific reference light, and generating composite light by superimposing the reproduction light on the reproduction-specific reference light; and

detecting means for detecting the composite light generated by the reproducing optical system.

15. An optical information reproducing apparatus according to claim 14, wherein the reproducing optical system performs the irradiation with the reproduction-specific reference light and the collection of the reproduction light on the same side of the information recording layer so that the reproduction-specific reference light and the reproduction light are arranged coaxially.

16. An optical information reproducing apparatus according to claim 14, wherein the reproduction-specific reference light generating means generates the reproduction-specific reference light that is spatially modulated in phase.

17. An optical information reproducing apparatus according to claim 14, further comprising a flying-type head body that accommodates the reproduction-specific reference light generating means, the reproducing optical system and the detecting means, and flies over the optical information recording medium.

18. An optical information reproducing method for reproducing information through the use of holography from an optical information recording medium having an information recording layer in which information is recorded in the form of an interference pattern resulting from interference between information light that is spatially modulated in phase based on information to be recorded, and recording-specific reference light, the method comprising:

the step of generating reproduction-specific reference light;

the reproducing step in which the information recording layer is irradiated with the reproduction-specific reference light, reproduction light that is generated from the information recording layer irradiated with the reproduction-specific reference light is collected, and composite light is generated by superimposing the reproduction light on the reproduction-specific reference light; and

the step of detecting the composite light.

19. An optical information reproducing method according to claim 18, wherein, in the reproducing step, the irradiation with the reproduction-specific reference light and the collection of the reproduction light are performed on the same side of the information recording layer so that the reproduction-specific reference light and the reproduction light are arranged coaxially.

20. An optical information reproducing method according to claim 18, wherein the step of generating the reproduction-specific reference light generates the reproduction-specific reference light that is spatially modulated in phase.

21. An optical information recording/reproducing apparatus for recording information on an optical information recording medium having an information recording layer in which information is recorded through the use of holography, and for reproducing the information from the information recording medium, the apparatus comprising:

information light generating means for generating information light by spatially modulating a phase of light based on information to be recorded;

recording-specific reference light generating means for generating recording-specific reference light;

reproduction-specific reference light generating means for generating reproduction-specific reference light;

a recording/reproducing optical system for irradiating the information recording layer with the information light generated by the information light generating means and the recording-specific reference light generated by the recording-specific reference light generating means when recording information so that the information is recorded in the information recording layer in the form of an interference pattern resulting from interference between the information light and the recording-specific reference light, and irradiating the information recording layer with the reproduction-specific reference light generated by the reproduction-specific reference light generating means, collecting reproduction light that is generated from the information recording layer irradiated with the reproduction-specific reference light, and generating composite light by superimposing the reproduction light on the reproduction-specific reference light when reproducing information; and

detecting means for detecting the composite light generated by the recording/reproducing optical system.

22. An optical information recording/reproducing apparatus according to claim 21, wherein the recording/reproducing optical system performs the irradiation with the information light, the recording-specific reference light and the reproduction-specific reference light and the collection of the reproduction light on the same side of the information recording layer so that the information light, the recording-specific reference light, the reproduction-specific reference light and the reproduction light are arranged coaxially.

23. An optical information recording/reproducing apparatus according to claim 22, wherein:

the information light generating means, the recording-specific reference light generating means, and the reproduction-specific reference light generating means respectively generate the information light, the recording-specific reference light, and the reproduction-specific reference light that are linearly polarized in the same direction; and

the recording/reproducing optical system has;

a quarter-wave plate for converting the information light and the recording-specific reference light from first linearly polarized light to circularly polarized light to irradiate the information recording layer with the same, and converting the reproduction light generated from the information recording layer from circularly polarized light to second linearly polarized light whose direction of polarization is orthogonal to that of the first linearly polarized light; and

a polarization separation optical element for achieving separation between an optical path of the information light, the recording-specific reference light, and the reproduction-specific reference light yet to pass through the quarter-wave plate and an optical path of return light from the optical information recording medium that has passed through the quarter-wave plate, according to a difference in directions of polarization.

24. An optical information recording/reproducing apparatus according to claim 21, wherein the recording-specific reference light generating means generates the recording-specific reference light that is spatially modulated in phase, and the reproduction-specific reference light generating means generates the reproduction-specific reference light that is spatially modulated in phase.

25. An optical information recording/reproducing apparatus according to claim 24, wherein the information light generating means spatially modulates the phase of the light in accordance with a phase modulation pattern determined based on the information to be recorded and a phase modulation pattern of the recording-specific reference light.

26. An optical information recording/reproducing apparatus according to claim 21, further comprising a flying-type head body that accommodates the information light generating means, the recording-specific reference light generating means, the reproduction-specific reference light generating means, the recording/reproducing optical system and the detecting means, and flies over the optical information recording medium.

27. An optical information recording/reproducing method for recording information on an optical information recording medium having an information recording layer in which information is recorded through the use of holography, and for reproducing the information from the information recording medium, the method comprising:

the step of generating information light by spatially modulating a phase of light based on information to be recorded;

the step of generating recording-specific reference light;

the recording step in which the information recording layer is irradiated with the information light and the recording-specific reference light so that the information is recorded on the information recording layer in the form of an interference pattern resulting from interference between the information light and the recording-specific reference light;

the step of generating reproduction-specific reference light;

the reproducing step in which the information recording layer is irradiated with the reproduction-specific reference light, reproduction light that is generated from the information recording layer irradiated with the reproduction-specific reference light is collected, and composite light is generated by superimposing the reproduction light on the reproduction-specific reference light; and

the step of detecting the composite light.

28. An optical information recording/reproducing method according to claim 27, wherein the irradiation with the information light, the recording-specific reference light and the reproduction-specific reference light and the collection of the reproduction light are performed on the same side of the information recording layer so that the information light, the recording-specific reference light, the reproduction-specific reference light and the reproduction light are arranged coaxially.

29. An optical information recording/reproducing method according to claim 27, wherein the step of generating the recording-specific reference light generates the recording-specific reference light that is spatially modulated in phase, and the step of generating the reproduction-specific reference light generates the reproduction-specific reference light that is spatially modulated in phase.

30. An optical information recording/reproducing method according to claim 29, wherein, in the step of generating the information light, the phase of the light is spatially modulated in accordance with a phase modulation pattern determined based on the information to be recorded and a phase modulation pattern of the recording-specific reference light.