JP2001142379A - Optical recording medium and its reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately read diffracted light even for the obliquely irradiating light. SOLUTION: The diffused light of a light source 11 is collimated to parallel beams by a convex lens 12, and the parallel beams are transmitted through a half mirror 13, condensed to the light (incident angle i=0) going toward the center axis O of a cylinder by a convex type cylindrical lens 14, and made incident on and reflected and diffracted by a hologram surface. The diffracted light is collimated to parallel beams by the lens 14, and the parallel beams are reflected by the mirror 13 and formed into an image on an image-formation surface 16 by a convex lens 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium on which a hologram representing information is formed, and a reproducing apparatus therefor.

[0002]

FIG. 8 shows a conventional transmission type optical recording medium 100.
FIG. 9 shows a conventional reflective optical recording medium 100b. In the transmission type optical recording medium 100a, a concavo-convex pattern of a computer hologram (hereinafter, also simply referred to as hologram) 102 is formed on a transparent card-like substrate 101, and in the reflection type optical recording medium 100b, the concavo-convex pattern is formed. A reflective film (not shown) is further formed on the substrate (on the substrate 101 side). For this reason, when reproducing the transmission type optical recording medium 100a, as shown in FIG. 8, when the hologram 102 is irradiated with, for example, the light of the laser light emitting unit 103, the diffracted light is directed to the opposite side (transmission side). When the hologram reproduction pattern 104 appears and the reflection type optical recording medium 100b is reproduced, the hologram 102 is irradiated with a laser beam as shown in FIG. The hologram reproduction pattern 104 of FIG. This hologram reproduction pattern 104
When the reading optical system is arranged at the position of, and when a large number of holograms 102 formed on the plane of the optical recording media 100a and 100b are reproduced, the optical recording media 100a and
100b and the reproducing apparatus side (light source, reading optical system) are relatively moved in parallel with the planes of the optical recording media 100a and 100b.

[0003]

However, the laser beam is perpendicular to the uneven pattern on the plane (incident angle i =
0) but not obliquely (incident angle i ≠ 0), the diffraction angle θ including the 0th-order diffracted light varies depending on the incident angle i,
For this reason, since the hologram reproduction pattern cannot be read accurately, there arises a problem that a highly accurate positioning mechanism between the optical recording medium and the reproduction device is required. Here, FIG. 10 shows a case where light is obliquely applied to a transmission type optical recording medium 100a, and FIG.
0b diffracted light (m
= 0), + 1st-order diffracted light (m = 1), -1st-order diffracted light (m =
-1), + 2nd-order diffracted light (m = 2), -2nd-order diffracted light (m = 2)
-2), and the following equation holds. sin θ−sini = mλ / d Therefore, information cannot be read unless the hologram is made flat, and when the optical recording medium itself or an article to which the optical recording medium is attached has various surface shapes, the information is attached to the surface shape. A hologram with a different shape could not be attached.

Accordingly, the present invention provides an optical recording medium having a computer generated hologram having a free surface shape such as matching the shape of an article, and an optical recording medium capable of accurately reading diffracted light output from the computer generated hologram of the optical recording medium. It is an object to provide a medium reproducing device.

[0005]

According to the present invention, in order to achieve the above-mentioned object, a reflection type or transmission type hologram representing information is formed on a cylindrical or spherical curved base material, or is formed on a flat surface. After forming on the base material, curve it to form a curved surface,
The incident angle of all light incident on the curved surface on which the hologram is formed is set to “0”. That is, according to the present invention, in an optical recording medium in which a computer generated hologram representing information by diffracted light to which readout light is incident and output is formed, the computer generated hologram is formed on a curved substrate, or a planar hologram is formed. An optical recording medium is provided in which a computer generated hologram having a curved incident surface of the readout light is formed by forming a curved surface after forming the substrate.

Further, according to the present invention, there is provided a reproducing apparatus for reading out information by diffracted light output from the computer generated hologram on an optical recording medium on which a computer generated hologram having a curved light incident surface is formed. An optical system that controls the incident angles of all the readout lights incident on the curved surface shape of the computer generated hologram to be “0” and forms an image of the diffracted light output from the computer generated hologram. An apparatus for reproducing an optical recording medium configured to read information formed by the optical system is provided.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a state in which parallel light is incident on the transmission type hologram pattern formed on the convex curved surface and diffracted. In FIG. 1, the curvature of the hologram pattern: a [mm] The grating pitch of the hologram pattern: d [μm] The wavelength of the light source: λ [μm] The diameter of the incident light beam of the light source: b [mm] The imaging distance: f [mm] , The central light 1 of the parallel incident light beam of diameter = b (incident angle i
= 0) is diffracted by the transmission hologram pattern, and as the diffracted light in the direction orthogonal to the image forming position (distance f), the distance of the + 1st-order diffracted light (m = 1) = g0 + −1st-order diffracted light (m = −) 1) = g0−. The diffraction angle in this case is d / λ [rad], and
Since the incident angle i = 0, the imaging distance g0 ± becomes f * d / λ.

FIG. 1 also shows an image formation position (in the case where light 2 (incident angle i ≠ 0) at a position x from the center light 1 of a parallel incident light beam of diameter = b is diffracted by a transmission hologram pattern ( As the diffracted light in the direction orthogonal to the distance f), the distance of the + 1st-order diffracted light (m = 1) = gx + the distance of the −1st-order diffracted light (m = −1) = gx−the distance of the 0th-order diffracted light (m = 0) = gx0. If the thickness of the transmission hologram pattern is ignored, x = gx0. Further, the incident angle i = sin ⁻¹ x / a The diffraction angle θ ± = sin ⁻¹ (± λ / d + sini) The imaging position gx ± = x + f * sin ⁻¹ (± λ / d + sini). Therefore, when the parallel light enters the hologram, the diffracted light cannot be accurately read.

FIG. 2 shows a state in which not the parallel light but the light directed toward the center of curvature is incident and diffracted on the transmission hologram pattern formed on the convex curved surface as in FIG. In this case, the imaging positions of the diffracted light of the central light 1 (incident angle i = 0) and the light 2 (incident angle i = 0) at a distance x from the central light 1 are always irrespective of the size of x. Since they are the same, the diffracted light can be read accurately. This specific example is shown in Table 1.

[0010]

[Table 1]

FIG. 3 shows a state where the diffused light of the light source 10 is collimated by the convex lens 11, and the parallel light is incident on the reflection type hologram pattern formed on the convex curved surface and diffracted. In this case, the zero-order diffracted light (reflected light on the surface of the hologram pattern that does not depend on the diffraction) is a light (incident angle i ≠ 0) away from the center of the incident light (incident angle i = 0). Diffracted light cannot be accurately read because the light is diffused under the influence of the curvature.
Note that diffracted light of ± 1st order or more depends on the incident angle i as described in FIG.

FIGS. 4 and 5 show a first embodiment of the present invention, which is formed in a cylindrical convex surface having a curvature in the vertical direction of the drawing of FIG. 4 and having no curvature in a direction perpendicular to the drawing. 1 shows a reflection hologram pattern (cylindrical convex hologram pattern) 10-1 and a reproducing apparatus therefor. 4 and 5
, The diffused light from a light source 11 such as a laser light source is collimated by a convex lens 12, and the parallel light is
3, the light is condensed by the convex cylindrical lens 14 into light (incident angle i = 0) directed toward the central axis O of the cylinder, and this light enters the hologram surface and is reflected and diffracted.

In this case, the diffracted light in the vertical direction in the drawing is diffused by a cylindrical curvature, so that the light in the diffused direction is parallelized by the convex cylindrical lens 14, and the parallel light is reflected by the half mirror 13. An image is formed on an image plane 16 by a convex lens 15 for image formation. A two-dimensional image sensor such as a CCD is disposed on the image plane 16.
Here, the focal length of the convex cylindrical lens 14 =
a, the distance between the convex cylindrical lens 14 and the center of the hologram = b, the diffraction angle θ becomes b / a times (<1) by the convex cylindrical lens 14.

FIG. 6 shows a reflection hologram pattern (spherical convex hologram pattern) 10-2 formed on a convex surface of a sphere and a reproducing apparatus therefor as a second embodiment of the present invention. In FIG. 6, diffused light from a light source 11 such as a laser light source is collimated by a convex lens 12, and after passing through a half mirror 13, the parallel light is converted into light (incident angle i = 0) toward the center of the sphere by a convex lens 17. The light is collected, incident on the hologram surface, reflected and diffracted. In this case, since the diffracted light is diffused in all directions by the spherical surface, the diffused light is collimated by the convex lens 17, and the parallel light is reflected by the half mirror 13 to form a convex lens for imaging (not shown in FIG. An image is formed on an image plane 16 by the same lens as the convex lens 15).

FIG. 7 shows, as a third embodiment of the present invention, a reflection type hologram pattern (cylindrical concave hologram pattern) 10-3 formed on a cylindrical concave surface and a reproducing apparatus therefor. In FIG. 7, a light source 11 such as a laser light source
Is diffused by a concave cylindrical lens 18 disposed on the central axis of a cylinder after passing through a half mirror 13, and the diffused light is collimated by a concave concave hologram pattern 10. −
3 is reflected and diffracted. Since the diffracted light in this case is condensed by a cylindrical curvature, the light is collimated by a concave cylindrical lens 18, and the parallel light is reflected by a half mirror 13 to form a convex lens for image formation (not shown in FIG. Is substantially the same as the convex lens 15).

In the above embodiment, an optical recording medium on which a reflection hologram is formed has been described. However, the present invention can be applied to an optical recording medium on which a transmission hologram is formed. When an apparatus for reproducing this transmission hologram is configured, an imaging element may be arranged at an imaging position on the transmission side of the curved surface. In the above embodiment, the base material on which the hologram is formed has a curved surface. However, a hologram is formed on a flat base material, and the hologram is attached to a member having a curved surface to form a curved surface. It can also be curved to form.

Therefore, according to the present invention, in addition to the inventions described in the claims, the following inventions are provided. (1-1) An optical recording medium in which a reflective hologram representing information is formed on a cylindrical convex surface. (1-2) An optical recording medium in which a reflection hologram representing information is formed on a convex surface of a sphere. (1-3) An optical recording medium in which a reflective hologram representing information is formed on a cylindrical concave surface. (1-4) An optical recording medium in which a reflection hologram representing information is formed on a concave surface of a sphere. (1-5) An optical recording medium in which a transmission hologram representing information is formed on a cylindrical convex surface. (1-6) An optical recording medium in which a transmission hologram representing information is formed on a convex surface of a sphere. (1-7) An optical recording medium in which a transmission hologram representing information is formed on a cylindrical concave surface. (1-8) An optical recording medium in which a transmission hologram representing information is formed on a concave surface of a sphere. (2-1) An apparatus for reproducing an optical recording medium in which a reflection type hologram representing information is formed on a cylindrical convex surface, wherein the parallel light is condensed to light directed toward the central axis of the cylindrical shape and the reflection type hologram is condensed. An optical recording device that has a convex cylindrical lens that collimates light reflected, diffracted, and diffused by the reflection hologram while being incident on the hologram, and reads the diffracted light collimated by the convex cylindrical lens. Media playback device. (2-2) An apparatus for reproducing an optical recording medium in which a reflection hologram representing information is formed on a convex surface of a sphere, wherein parallel light is condensed to light directed toward the center of the sphere to form the reflection hologram on the reflection hologram. With the incident, reflected by the reflection hologram, diffracted, having a convex lens that forms an image of the diffused light,
An optical recording medium reproducing apparatus configured to read the diffracted light formed by the convex lens. (2-3) An apparatus for reproducing an optical recording medium in which a reflective hologram representing information is formed on a cylindrical concave surface, wherein parallel light is diffused at the central axis of the cylindrical shape to be incident on the reflective hologram. An apparatus for reproducing an optical recording medium, further comprising a concave cylindrical lens for collimating the light reflected, diffracted and diffused by the reflection hologram, and reading the diffracted light collimated by the concave cylindrical lens. (2-4) An apparatus for reproducing an optical recording medium in which a reflection hologram representing information is formed on a concave surface of a sphere, wherein parallel light is diffused at the center of the sphere and made incident on the reflection hologram. The reflective hologram has a concave lens that forms an image of light reflected, diffracted, and collimated,
An optical recording medium reproducing apparatus for reading the diffracted light formed by the concave lens. (2-5) An apparatus for reproducing an optical recording medium in which a transmission type hologram representing information is formed on a cylindrical convex surface, wherein the parallel light is condensed to light directed toward a central axis of the cylindrical shape, and the transmission type hologram is condensed. An apparatus for reproducing an optical recording medium, comprising: a convex cylindrical lens that is incident on a hologram; and reads light diffracted through the transmission hologram. (2-6) An apparatus for reproducing an optical recording medium in which a transmission type hologram representing information is formed on a convex surface of a sphere, wherein parallel light is condensed to light directed toward the center of the sphere to form the transmission type hologram. An apparatus for reproducing an optical recording medium, comprising a convex lens for incidence, and reading light diffracted through the transmission hologram. (2-7) An apparatus for reproducing an optical recording medium in which a transmission hologram representing information is formed on a cylindrical concave surface, wherein parallel light is diffused at the central axis of the cylinder to be incident on the transmission hologram. Has a concave cylindrical lens,
An apparatus for reproducing an optical recording medium configured to read light diffracted through the transmission hologram. (2-8) An apparatus for reproducing an optical recording medium in which a transmission type hologram representing information is formed on a concave surface of a sphere, comprising: a concave lens for diffusing parallel light at the center of the sphere to enter the transmission type hologram. An apparatus for reproducing an optical recording medium, wherein the apparatus has a function of reading light diffracted by transmitting through the transmission hologram.

[0018]

As described above, the optical recording medium of the present invention has a computer-generated hologram in which the incident surface of the readout light has a curved surface. In addition, the optical recording medium of the present invention can be attached. Further, the apparatus for reproducing an optical recording medium according to the present invention has an effect that information can be accurately read from an optical recording medium on which a computer hologram having a curved light incident surface is formed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a state in which parallel light is incident and diffracted on a transmission type hologram pattern formed on a convex curved surface.

FIG. 2 is an explanatory diagram showing a state in which light traveling toward a center of curvature is incident on a transmission type hologram pattern formed on a convex curved surface and diffracted;

FIG. 3 is an explanatory diagram showing a state in which parallel light is incident and diffracted on a reflective hologram pattern formed on a convex curved surface.

FIG. 4 is a configuration diagram showing an optical recording medium and a reproducing apparatus thereof according to the first embodiment of the present invention.

FIG. 5 is a configuration diagram illustrating an optical recording medium and a reproducing apparatus thereof according to the first embodiment of the present invention.

FIG. 6 is a configuration diagram showing an optical recording medium and a reproducing apparatus thereof according to a second embodiment of the present invention.

FIG. 7 is a configuration diagram showing an optical recording medium and a reproducing device thereof according to a third embodiment of the present invention.

FIG. 8 is a configuration diagram showing a conventional optical recording medium and a reproducing apparatus therefor.

FIG. 9 is a configuration diagram showing another conventional optical recording medium and a reproducing apparatus therefor.

FIG. 10 is an explanatory diagram showing diffracted light by a transmission hologram.

FIG. 11 is an explanatory diagram showing diffracted light by a reflection hologram.

[Explanation of symbols]

 10-1 Cylindrical convex hologram pattern 10-2 Spherical convex hologram pattern 10-3 Cylindrical concave hologram pattern 12, 15, 17 convex lens 14 convex cylindrical lens 18 concave cylindrical lens

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2K008 AA04 AA13 BB08 CC01 CC03 EE01 EE04 FF27 HH07 HH19 5D090 AA03 BB16 BB18 CC04 DD03 DD05 KK09 KK11 LL02 LL03

Claims (2)

[Claims] 1. An optical recording medium on which a computer generated hologram representing information is formed by diffracted light which is incident upon and output from a readout light, wherein the computer generated hologram is formed on a curved base material or a flat base material. An optical recording medium characterized in that a computer generated hologram having a curved incident surface of the readout light is formed by forming a curved surface after forming the same. 2. A reproducing apparatus for reading out information by diffracted light output from the computer generated hologram on an optical recording medium on which a computer generated hologram having a curved light incident surface is formed, wherein the computer generated hologram is provided. An optical system that controls the incident angles of all of the readout light incident on the curved surface shape to be “0” and forms an image of diffracted light output from the computer generated hologram, An apparatus for reproducing an optical recording medium configured to read imaged information.