Optical Information Reproduction Device and Optical Information Reproduction Method

Patent metadata

Field	Value
Publication number	US-2016307591-A1
Application number	US-201315101239-A
Country	US
Kind code	A1
Filing date	Dec 4, 2013
Priority date	Dec 4, 2013
Publication date	Oct 20, 2016
Grant date	—

Abstract

Provided are an optical information reproduction device and a method therefor with which the influence of reference light reflected from the surface of a disk can be reduced, thereby enabling data to be reproduced in a stable manner in an optical information reproduction device that uses holography. The information reproduction device, which reproduces from a recording medium information that has been recorded on the recording medium by the formation of a hologram, is equipped with: a light output unit that emits laser light; an optical system that generates reference light from the laser light emitted from the light output unit; an objective lens that reproduction signal light reproduced by the reference light with which the recording medium has been irradiated enters; a light detector that receives the reproduction signal light propagated by the objective lens; a medium-reflected light reduction unit that reduces the amount of medium-reflected light (generated when the recording medium reflects the reference light) with which the light detector is irradiated; and a control unit that controls the operation of the information reproduction device.

First claim

1 . An information reproduction device for reproducing from a recording medium information recorded on the recording medium by formation of a hologram, the device comprising:
a light output unit configured to emit laser light; an optical system configured to generate reference light from the laser light emitted from the light output unit; an objective lens configured to receive reproduction signal light incident thereon, the reproduction signal light being reproduced by irradiation of the recording medium with the reference light; a light detector configured to receive the reproduction signal light propagated through the objective lens; a medium-reflected light reduction unit configured to reduce irradiation of the light detector with medium-reflected light generated by reflection of the reference light on the recording medium; and a control unit configured to control operation of the information reproduction device.

2 . The information reproduction device according to claim 1 , comprising
a reference light angle adjustment unit configured to adjust an angle of incidence of the reference light on the recording medium, wherein when the reference light angle adjustment unit adjusts the angle of incidence of the reference light within a specified range, information is reproduced from a hologram multiplex-recorded on the recording medium.

3 . The information reproduction device according to claim 2 , wherein
the medium-reflected light reduction unit shields the medium-reflected light.

4 . The information reproduction device according to claim 3 , comprising
a lens configured to receive the reproduction signal light incident thereon, the reproduction signal light being made into substantially parallel light by the objective lens, wherein the medium-reflected light reduction unit is arranged in an optical path between the objective lens and the lens.

5 . The information reproduction device according to claim 3 , wherein
the medium-reflected light reduction unit is arranged at a position where the medium-reflected light that passed through the objective lens is substantially collected.

6 . The information reproduction device according to claim 4 , wherein
the collection position of the medium-reflected light changes depending on the angle of incidence of the reference light, and the medium-reflected light reduction unit is sized to shield the medium-reflected light collected on the collection position that changes depending on the angle of incidence of the reference light adjusted in the specified range.

7 . The information reproduction device according to claim 4 , wherein
the medium-reflected light reduction unit is sized to shield the medium-reflected light generated by incidence of the reference light at the specified angle of incidence.

8 . The information reproduction device according to claim 4 , comprising
a moving unit configured to move a position of the medium-reflected light reduction unit, wherein the moving unit moves the position of the medium-reflected light reduction unit based on the collection position of the medium-reflected light that changes depending on the angle of incidence of the reference light.

9 . The information reproduction device according to claim 4 , wherein
the control unit calculates as an angle error signal an error from an optimum angle at a time of reproduction of the reference light, and the reference light angle adjustment unit adjusts the angle of incidence of the reference light based on the angle error signal.

10 . The information reproduction device according to claim 2 , wherein
the medium-reflected light reduction unit reduces energy density of the medium-reflected light on the light detector to a level of the energy density of a detection signal or lower.

11 . An information reproduction method for reproducing from a recording medium information recorded on the recording medium by formation of a hologram, the method comprising the steps of:
emitting laser light; generating reference light from the laser light emitted from the light output unit; generating reproduction signal light by irradiation of the recording medium with the reference light; receiving the reproduction signal light; and reducing medium-reflected light generated by reflection of the reference light on the recording medium.

12 . The information reproduction method according to claim 11 , comprising the step of
adjusting an angle of incidence of the reference light on the recording medium, wherein when the angle of incidence of the reference light is adjusted within a specified range in the step of adjusting the reference light angle, information is reproduced from a hologram multiplex-recorded on the recording medium.

13 . The information reproduction method according to claim 12 , wherein
the step of reducing the medium-reflected light shields the medium-reflected light.

14 . The information reproduction method according to claim 12 , comprising the step of
calculating as an angle error signal an error from an optimum angle at a time of reproduction of the reference light and adjusting the angle of incidence of the reference light based on the angle error signal.

15 . The information reproduction method according to claim 12 , wherein
the step of reducing the medium-reflected light reduces energy density of the medium-reflected light to a level of energy density of a detection signal or lower.

Assignees

• Hitachi Consumer Electronics

Inventors

• Hosaka Makoto
• Fujita Shinji

Classifications

• G11B7/1353 Primary

  Diffractive elements, e.g. holograms or gratings {(diffraction gratings per se G02B5/18; holograms per se G02B5/32; grating systems G02B27/44)} · CPC title

• G11B7/1374

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

• G11B7/0065

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

• G11B7/005

  Reproducing (G11B7/0065 takes precedence) · CPC title

• G11B7/1381

  Non-lens elements for altering the properties of the beam, e.g. knife edges, slits, filters or stops (G11B7/1353 - G11B7/1369 take precedence) · CPC title