Optical information recording/reproduction device and adjustment method

Patent metadata

Field	Value
Publication number	US-2016111123-A1
Application number	US-201314892019-A
Country	US
Kind code	A1
Filing date	Jun 14, 2013
Priority date	Jun 14, 2013
Publication date	Apr 21, 2016
Grant date	—

Abstract

The optical information recording/reproduction device for recording information by irradiating an optical information recording medium with signal light and reference light to form a hologram, and reproducing the information by irradiating the hologram with the reference light, wherein the optical information recording/reproduction device is provided with a branching element for branching laser light from a laser light source into signal light and reference light, a spatial light modulation unit for adding two-dimensional information to the signal light, an objective lens for irradiating an optical information recording medium with the signal light, a photodetector for detecting diffracted light from the optical information recording medium when irradiated with the reference light, and an optical axis adjustment unit disposed between the laser light source and the branching element, the optical axis adjustment unit adjusting the optical axis of the laser light.

First claim

1 : An optical information recording/reproduction device that irradiates an optical information recording medium with signal light and reference light to form a hologram to record information, and irradiates the hologram of the optical information recording medium with the reference light to reproduce information, the optical information recording/reproduction device comprising:
a laser light source configured to emit laser light; a branching element configured to branch the laser light from the laser light source to the signal light and the reference light; a spatial light modulation unit for adding two-dimensional information to the signal light; an objective lens for irradiating the optical information recording medium with the signal light; a photodetector configured to detect diffracted light from the optical information recording medium when the optical information recording medium is irradiated with the reference light; an optical axis adjustment unit arranged between the laser light source and the branching element, and configured to adjust an optical axis of the laser light

2 : The optical information recording/reproduction device according to claim 1 , wherein
the optical axis adjustment unit adjusts angles of the signal light and the reference light incident on the optical information recording medium to cause the signal light and the reference light to interfere with each other on the optical information recording medium.

3 : The optical information recording/reproduction device according to claim 1 , further comprising:
a wavefront measurement unit configured to measure a wavefront aberration of the laser light, wherein the optical axis adjustment unit adjusts the optical axis of the laser light to cause the measured wavefront aberration to become small.

4 : The optical information recording/reproduction device according to claim 1 , wherein
the photodetector detects at least a part of the signal light, and the optical axis adjustment unit adjusts the optical axis of the laser light, based on the detected result.

5 : The optical information recording/reproduction device according to claim 4 , wherein
the optical axis adjustment unit adjusts the optical axis of the laser light to cause the signal light to be incident on a center of the photodetector.

6 : The optical information recording/reproduction device according to claim 1 , wherein
a first optical element having first aberration sensitivity and a second optical element having second aberration sensitivity smaller than the first aberration sensitivity are arranged between the laser light source and the branching element, the second optical element is arranged at a side closer to the laser light source than the first optical element, and the optical axis adjustment unit drives the first optical element to adjust the optical axis of the laser light.

7 . (canceled)

8 : The optical information recording/reproduction device according to claim 1 , wherein
a relay lens is arranged between the laser light source and the branching element.

9 : The optical information recording/reproduction device according to claim 8 , wherein
the optical axis adjustment unit drives the relay lens to adjust the optical axis of the laser light.

10 : The optical information recording/reproduction device according to claim 8 , wherein
a beam shaping element is arranged at a side close to the laser light source than the relay lens, and the optical axis adjustment unit drives the beam shaping element to adjust the optical axis of the laser light.

11 : The optical information recording/reproduction device according to claim 8 , wherein
a wedge prism is arranged at a side closer to the laser light source than the relay lens, and the optical axis adjustment unit drives the wedge prism to adjust the optical axis of the laser light.

12 : The optical information recording/reproduction device according to claim 8 , wherein
a mirror that reflects the laser light is arranged at a side close to the laser light source than the relay lens, and the optical axis adjustment unit drives the mirror to adjust the optical axis of the laser light.

13 : An adjustment method of an optical axis in an optical information recording/reproduction device that irradiates an optical information recording medium with signal light and reference light to form a hologram to record information, and irradiates the hologram of the optical information recording medium with the reference light to reproduce information, the method comprising the steps of:
emitting a laser light by a laser light source; branching the laser light to a signal light and a reference light by a branching element; and adjusting an optical axis of the laser light by an optical axis adjustment unit arranged between the laser light source and the branching element.

14 : The adjustment method according to claim 13 , further comprising the step of:
measuring a wavefront aberration of the laser light, wherein the adjusting step adjusts the optical axis of the laser light to cause the measured wavefront aberration to become small.

15 : The adjustment method according to claim 13 , further comprising the step of:
detecting at least a part of the signal light, wherein the adjusting step adjusts the optical axis of the laser light, based on the detected result.

16 : An adjustment method of an optical axis in an optical information recording/reproduction device that irradiates an optical information recording medium with signal light and reference light to form a hologram to record information, and irradiates the hologram of the optical information recording medium with the reference light to reproduce information, the method comprising the steps of:
emitting laser light by a laser light source; branching the laser light to signal light and reference light by a branching element; detecting at least a part of the signal light by a photodetector; and
adjusting arrangement of the photodetector to cause the signal light to be incident on a center of the photodetector, when the reference light interferes with the signal light at an upper surface and a lower surface of a recording layer of the optical information recording medium at a lowest reference light angle that is used for recording.

Assignees

• Hitachi Consumer Electronics

Inventors

• Nagayoshi Mayumi
• Hoshizawa Taku
• Yamazaki Kazuyoshi
• Hosaka Makoto

Classifications

• G11B7/0065 Primary

  Recording, reproducing or erasing by using optical interference patterns, e.g. holograms · CPC title

• G11B7/1374

  Objective lenses {(optical objectives per se G02B9/00)} · CPC title

• G11B7/1362

  Mirrors · CPC title

• G11B7/13927

  during transducing, e.g. to correct for variation of the spherical aberration due to disc tilt or irregularities in the cover layer thickness · CPC title

• G11B7/1359

  Single prisms · CPC title