Optical recording device, optical recording method, and information recording medium

Patent metadata

Field	Value
Publication number	US-10074428-B2
Application number	US-201214653547-A
Country	US
Kind code	B2
Filing date	Dec 21, 2012
Priority date	Dec 21, 2012
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

In a recording technique in which a plurality of light spots are simultaneously formed by using an ultra-short pulse laser and a spatial phase modulator, and a plurality of recording dots having refractive indexes different from those of the vicinities thereof are formed inside a recording medium, it is hard to make recording quality and a recording density compatible. Therefore, a plurality of dots are recorded at a predetermined dot pitch, and then other dots are recorded between the recorded dots.

First claim

The invention claimed is:

1. An optical recording method comprising:
a first step of simultaneously forming a plurality of dots, which have refractive indexes different from refractive indexes of the vicinities thereof and have a predetermined dot pitch, in a single plane of a recording medium by applying laser light to inside of the recording medium via a spatial phase modulator to which a two-dimensional pattern is applied; and
a second step, after the first step, of forming a plurality of next dots between neighboring ones of the formed dots formed in the first step in a same region of the single plane as the formed dots formed in the first step.

2. The optical recording method according to claim 1 , wherein the second step of forming the next dots is executed by changing a pattern of the spatial phase modulator.

3. The optical recording method according to claim 1 , wherein the second step of forming the next dots is also a step of simultaneously forming a plurality of dots.

4. The optical recording method according to claim 1 , wherein the predetermined dot pitch is 5 μm or more.

5. The optical recording method according to claim 1 , wherein the second step of forming the next dots is repeatedly executed.

6. The optical recording method according to claim 1 , wherein the predetermined dot pitch is determined on the basis of the following steps of:
(a) recording a test pattern while changing a dot pitch;
(b) evaluating recording quality for each dot pitch; and
(c) determining a dot pitch for which the recording quality is a predetermined level or higher as a result of the evaluation.

7. The optical recording method according to claim 6 , wherein, in the step of (c), the dot pitch is determined so that a number of divisions is the minimum.

8. An optical recording apparatus comprising:
a laser light source;
a stage on which a recording medium is placed;
a spatial phase modulator that is provided between the laser light source and the stage and to which a two-dimensional pattern for recording dots in the recording medium is applied;
a condensing optical system that forms a plurality of light spots corresponding to the two-dimensional pattern and forms a plurality of dots having a predetermined dot pitch in a single plane inside the recording medium; and
means for changing recording positions so that a plurality of next dots are recorded between neighboring ones of the recorded dots in a same region of the single plane as the recorded dots after forming the recorded dots.

9. The optical recording apparatus according to claim 8 , wherein the means for changing recording positions is realized by changing a pattern of the spatial phase modulator.

10. The optical recording apparatus according to claim 8 , wherein the means for changing recording positions is realized by moving the stage.

11. An optical recording apparatus comprising:
a laser light source;
a stage on which a recording medium is placed;
a spatial phase modulator that is provided between the laser light source and the stage and to which a two-dimensional pattern for recording dots in the recording medium is applied; and
a condensing optical system that forms a plurality of light spots corresponding to the two-dimensional pattern and forms a plurality of dots having a predetermined dot pitch in a single plane inside the recording medium,
wherein the spatial phase modulator is configured to change recording positions so that a plurality of next dots are recorded between neighboring ones of the recorded dots in a same region of the single plane as the recorded dots after forming the recorded dots.

Assignees

• Hitachi Ltd

Inventors

• Shiozawa Manabu
• Shimotsuma Yasuhiko
• Sakakura Masaaki
• Miura Kiyotaka
• NAKABAYASHI Miki

Classifications

• G11B7/0065

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

• G11B7/013

  for discrete information, i.e. where each information unit is stored in a distinct discrete location {, e.g. digital information formats within a data block or sector} · CPC title

• G11B7/128

  Modulators (G11B7/1245 takes precedence) · CPC title

• G11C13/048

  using other optical storage elements · CPC title

• G11B7/00455

  involving reflectivity, absorption or colour changes · CPC title