US 7,626,910 B2 · Optical information recording medium for holographic recording and method of holographic recording in optical information recording medium

Abstract

The optical information recording medium according to the present invention includes a transparent substrate having a first surface and a second surface, a recording layer that is arranged on the first surface of the transparent substrate, and a reflection layer arranged on the second surface of the transparent substrate. A hologram is recorded in the recording layer when a signal light and a reference light are incident from an incident side opposite to the transparent substrate. An optical density of the recording layer corresponding to the signal light decreases from the incident side toward the transparent substrate.

Claims16

Dependent claims

An optical information recording medium comprising:

a transparent substrate having a first surface and a second surface;
a recording layer arranged on the first surface of the transparent substrate, wherein
a hologram is recorded in the recording layer when a signal light and a reference light are incident from an incident side opposite to the transparent substrate,
a region in the recording layer, in which the hologram is recorded, contains portions of differing optical density and is conical, and
the optical density corresponding to the signal light in the region of the recording layer in which the hologram is recorded decreases from the incident side toward the transparent substrate;
and
a reflection layer arranged on the second surface of the transparent substrate;
wherein
the recording layer includes a high optical density layer and a low optical density layer corresponding to the signal light, and
the high optical density layer is arranged on the incident side relative to the low optical density layer.

7 more elements

A method of recording information on an optical information recording medium, the method comprising:

selecting an optical information recording medium, the medium comprising:
a transparent substrate having a first surface and a second surface;
a recording layer arranged on the first surface of the transparent substrate,
wherein
a hologram is recorded in the recording layer when a signal light and a reference light are incident from an incident side opposite to the transparent substrate,
a region in the recording layer, in which the hologram is recorded, contains portions of differing optical density and is conical, and
an optical density corresponding to the signal light in the region of the recording layer in which the hologram is recorded decreases from the incident side toward the transparent substrate, a reflection layer arranged on the second surface of the transparent substrate, and
a groove that is arranged on the second surface of the transparent substrate to form a track;
and
recording the hologram in the recording layer by irradiating the optical information recording medium with the signal light and the reference light through a lens,
wherein the optical density S(r, z) at a predetermined position in the recording layer is within a range expressed as
0.5
×
S
0
r
0
2
⁢
(
r
0
-
A
n
1
1
-
(
A
n
1
)
2
⁢
z
)
2
⁢
exp
⁡
(
2
⁢
r
2
r
0
2
)
≤
S
⁡
(
r
,
z
)
≤
2.0
×
S
0
r
0
2
⁢
(
r
0
-
A
n
1
1
-
(
A
n
1
)
2
⁢
z
)
2
⁢
exp
⁡
(
2
⁢
r
2
r
0
2
)
where S0 is the optical density of a center of a spot of the signal light at r=0 on a surface of the incident side of the recording layer at z=0, n1 is a refractive index of the recording layer, A is a numerical aperture of the lens, r0 is a radius of the spot of the signal light on the surface of the incident side, r is a distance from the center of the spot in a direction across the track, and z is a distance from the surface of the incident side into the recording layer.

96 more elements

Dependencies are inferred from the claim text.

Optical information recording medium for holographic recording and method of holographic recording in optical information recording medium

Life of this patent

Optical information recording medium for holographic recording and method of holographic recording in optical information recording medium

Life of this patent

Abstract

Claims16