JP2000057254A - Optical recording medium and information reader for optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium where hologram patterns are recorded in such form that many data can efficiently be read out at the time of reading and an information reader for the optical recording medium which can efficiently read recording information out of the optical recording medium. SOLUTION: Hologram patterns are recorded on an optical recording medium 10 while their diffraction angles and the arrangement angles of their recording parts are predetermined so that when plural hologram patterns 12 of the optical recording medium 10 are irradiated with light beams at the same time, their transmitted diffracted lights or reflected diffracted lights are imaged at specific positions on a specific two-dimensional plane. When information is read out of this optical recording medium, an efficient read is made by irradiating plural hologram patterns at the same time through a beam splitter 26 and the optical recording medium is conveyed in a specific direction and is read sequentially.

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 and an information reading apparatus therefor, and more particularly to an optical recording medium recorded as a hologram pattern suitable for a prepaid card, a credit card, a certification card, and the like, and the recorded information. The present invention relates to an information reading apparatus for reading an optical recording medium.

[0002]

2. Description of the Related Art Various types of cards are used. As a prepaid card, a credit card, a certification card, etc., those using a conventional magnetic recording medium are easily forged,
Since it can be tampered with, a card-type optical recording medium has attracted attention as an alternative to this, and among them, a hologram-based optical recording medium has been given particular importance as being effective for forgery and falsification. The optically readable card disclosed in Japanese Patent Publication No. 7-95341 is for recording and reproducing information using a hologram pattern.

In the conventional optical system of an information reading apparatus for reading a hologram pattern (diffraction grating) from a recording medium using a hologram, for example, Japanese Patent Publication No. 7-97388.
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-115, in order for a light beam from a light source to irradiate the entire recording medium, a spread light beam is used, and reflected and diffracted light from a plurality of hologram patterns is received to reproduce recorded information.

[0004]

In the above-mentioned conventional optical recording medium, the arrangement of the hologram pattern is limited, so that much information cannot be recorded / reproduced efficiently. Further, transmitted diffraction light transmitted through a hologram pattern of a conventional optical recording medium or reflection diffraction light reflected by a hologram pattern is diffracted only one-dimensionally, and thus, a plurality of image forming portions are linearly arranged on a light receiving surface. Therefore, the number of imaged portions that fit within a predetermined two-dimensional area is limited,
There has been a problem that the number of image forming regions of the hologram pattern that can be recognized by the image sensor having the light receiving surface of a predetermined aspect ratio is limited. Further, Japanese Patent Application Laid-Open No.
In the conventional information reading apparatus for an optical recording medium disclosed in Japanese Patent Application Laid-Open No. 8 (1996) -1995, although the light projecting means and the light receiving means are integrated, which contributes to downsizing, the reflected and diffracted light from the hologram pattern in a certain area Is received by the light receiving means divided into a plurality of blocks, and only a limited number of types of hologram patterns can be recognized, and different types of patterns different from each other cannot be recognized. That is, when reading the data by transporting the optical recording medium,
Since the number of hologram patterns that can be irradiated and read at the same time is limited, the amount of data that can be read per unit time is limited, and efficient reading cannot be performed.

Accordingly, in the present invention, when data is recorded on a recording medium by using a hologram pattern, an optical recording medium recorded in a recording form in which a large amount of data can be efficiently read at the time of reading, and a recording from such an optical recording medium. An object of the present invention is to provide an information reading device for an optical recording medium that can read information efficiently.

[0006]

In order to achieve the above object, according to the present invention, when a plurality of hologram patterns are simultaneously illuminated by light beams, the transmitted or reflected diffracted light of the plurality of hologram patterns falls within a predetermined two-dimensional plane. The diffraction angles of the plurality of hologram patterns and the arrangement angles of the recording portions are recorded in advance so as to form an image at a position, and when reading information from such an optical recording medium, the plurality of hologram patterns are simultaneously read. Irradiation achieves efficient reading.

That is, according to the present invention, in an optical recording medium on which a plurality of hologram patterns are recorded, when the plurality of hologram patterns are simultaneously irradiated with light beams, the transmitted diffraction light or the reflected diffraction light is irradiated by a predetermined amount. An optical recording medium is provided, wherein diffraction angles of the plurality of hologram patterns and an arrangement angle of a recording portion thereof are predetermined so that an image is formed at a predetermined position in a two-dimensional plane.

Further, according to the present invention, a light source for emitting light of a predetermined wavelength, spectral means for dispersing the light from the light source into a plurality of light beams, and a plurality of diffraction gratings are formed as a hologram pattern to form a two-dimensional light beam. When a light beam condensed by the optical means is irradiated on a recording medium arranged in a, the reflected light diffracted light or the transmitted diffracted light is received, and the means for reading the hologram pattern of the diffraction grating and the recording medium are Means for transporting the optical recording medium in a direction orthogonal to the spectral direction by the spectral means.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 5 is a plan view of an optical recording medium according to the present invention embodied as a business card size card (a prepaid card, an identification card, etc.). The card 10 has a plurality of optical recording portions 12 on its surface, and each recording portion 12 records hologram interference fringes. The interference pattern of the hologram is one mode of the diffraction grating, and the diffraction grating will be examined here. The relationship between the optical diffraction grating pitch p and the diffraction angle θ is as follows.
Then

[0010]

Equation 1 ± n sin θ = λ / p (1) n is represented by a natural number including 0. When n = 0, it is transmitted or reflected light of non-diffracted light, which is called zero-order diffracted light. On the other hand, when ± n, ordinary optical system (symmetric optical system)
Then, the diffracted light amounts are equal. As n increases, the amount of higher-order diffracted light decreases. Considering only n = 1, three light velocities are generated from the diffraction grating.

In the case of a parallel diffraction grating, one-dimensional diffracted light is generated. If only the positive direction of ± is discussed, it can be said that only one diffracted light is generated. JP-A-5-50788 described above.
In the technique disclosed in the publication, a plurality of diffraction grating groups having different arrangement angles and pitches of diffraction gratings are simultaneously irradiated to obtain a plurality of diffraction lights, and a detection pattern is recognized using the diffraction lights. In the present invention, not a parallel diffraction grating but a grating arranged in a specific pattern in both horizontal and vertical directions, and a computer is operated so that the diffracted light is arranged one-dimensionally or two-dimensionally. To generate a CGH (Computer Generated Hologram). As the hologram used in the present invention, for example, a monthly magazine "Oplus E" (published by New Technology Communications Co., Ltd .; No. 204; November 1996) can be used. In this specification, two-dimensionally diffracting means diffracting so as to spread vertically and horizontally on a two-dimensional plane as described above. One-dimensionally diffracting means diffracting in a predetermined direction on a straight line. Refers to

FIG. 6 shows a CGH developed by the present inventors prior to the present invention and applied for a patent (Japanese Patent Application No. 8-317053).
FIG. 1 is a block diagram schematically showing a method for manufacturing a master optical recording medium, a method for recording information on an optical recording medium, an apparatus for manufacturing an optical recording medium, and a method for manufacturing an optical recording medium. In this example, a prepaid card 10A as a card type optical recording medium is manufactured. The prepaid card 10A is provided with a plurality of recording portions 12, which are arranged. Now, assuming that character information is to be recorded in each of the recording portions 12, a signal of the character information is supplied to the input terminal IN1 and input to the image signal conversion circuit 50. The image signal conversion circuit 50 converts a character represented by the code information of the input digital signal into an image signal of a two-dimensional image dot pattern (input data in FIG. 7 described later).

This image signal is supplied to a numerical operation device 54 via a switch 52 or a multiplexer. The numerical calculation device 54 obtains a numerical value for obtaining an interference fringe pattern (holographic interferogram) of the hologram from the image signal of the dot pattern of the two-dimensional image using a predetermined algorithm without irradiating interference light. FIG. 7A is a diagram showing a procedure for obtaining an interference fringe pattern of a hologram from a two-dimensional image. Preferably, a computer capable of high-speed operation is used as the numerical operation device. FIG. 7B shows an example in which a grid arranged in a specific pattern in both the horizontal and vertical directions used in the present invention is created, and an arithmetic operation is performed using a computer so that the diffracted light is arranged two-dimensionally. It is a photograph which shows an example of what generated CGH of value.

The numerical operation device 54 is configured to output coordinate data corresponding to the resolution of an electron beam exposure device 58 which is a drawing device described later. Before actually performing drawing, coordinate data obtained by numerical operation is fed back and compared with input data, and recalculation is performed a plurality of times to reduce an error between the two.

An output signal of the numerical operation device 54 is converted into a signal of a predetermined format by an encoder 56 and is input to an electron beam exposure device 58. The electron beam exposure device 58 is originally used to draw a circuit arrangement pattern when an IC or LSI is manufactured. Here, the pattern (output data) of the interference fringes shown in FIG. It is used for drawing on the primary recording medium 60. The primary recording medium 60 is referred to as a primary recording medium 60 to distinguish it from the optical recording medium 10A which is a final product. As the primary recording medium 60, a medium in which a photoresist as a photosensitive resin as a medium to be exposed is applied on a substrate such as glass is used. The primary recording medium 60 is mounted on a stepper 62 (stage controller), and the stepper 62 receives an electron beam 66 from a signal from an electron beam exposure device 58.
Can be moved in two directions X-Y on a plane perpendicular to. It should be noted that drawing by an electron beam is compared with drawing by a laser beam used for manufacturing a conventional optical recording medium.
It is possible to draw an extremely delicate and precise pattern, and it can be said that this is suitable for drawing a pattern of interference fringes of a hologram.

The primary recording medium 60 is processed as a photomask master, a plurality of secondary recording media are produced from the primary recording medium 60 by light exposure from the photomask master, and the secondary recording medium is used as a master. It is also possible to manufacture an optical recording medium 10A as a final product through an optical disk manufacturing process.

Now, assuming that data consisting of 300 English characters (including numbers) is to be recorded on the prepaid card, character string data serially input from the input terminal IN1 is sequentially transmitted to the image signal conversion circuit 50. It is converted into an image signal, subjected to a numerical operation process by a predetermined algorithm in a numerical operation device 54, converted into data of a predetermined format by an encoder 56, supplied to an electron beam exposure device 58, and deflected by an electron beam 66. Then, drawing is performed on the primary recording medium 60. At this time, the electron beam exposure device 58
Controls the stepper 62 so that the 300 recording portions 12 are in three rows, and the electron beam 6 is arranged such that 100 recording portions are arranged in each row.
The primary recording medium 60 is moved in the XY axis direction on a plane perpendicular to 6.

FIG. 1 shows an optical recording medium of the present invention for reading a recorded image by irradiating an optical recording medium of the present invention with a parallel light beam (laser beam from a laser diode or the like) as a light beam of a single wavelength (monochromatic light beam). 1 is a schematic diagram of a preferred embodiment of a medium information reading device. The information reading device for an optical recording medium includes a light source 16 that emits light of a predetermined wavelength, a beam splitter 26 as a spectral unit that splits a light beam from the light source 16 into a plurality of light beams, and a hologram pattern 12 of the optical recording medium 10. When the light split by the beam splitter 26 is irradiated, the light receiving element (image sensor) 20 as a means for receiving the reflected light diffracted light or the transmitted diffracted light and reading a reproduced image is provided. Also, it is not possible to provide a light beam forming plate as a shielding means having a pinhole as a means disposed between the beam splitter 26 and the optical recording medium 10 and for limiting the irradiation range of the optical recording medium 10 by the light beam from the beam splitter 26. This is a preferred embodiment. As the image sensor 20, a CCD camera or a CCD image sensor can be used.

As shown in FIG. 5, the optical recording medium 10 has a plurality of diffraction gratings formed as a hologram pattern 12 and is two-dimensionally arranged in the X-axis direction and the Y-axis direction. . As shown in FIG. 1, the X-axis direction corresponds to the longitudinal direction of the card as the optical recording medium 10, and the Y-axis direction corresponds to the Y-axis direction.
The axial direction corresponds to the lateral direction of the card. The Z direction corresponds to the thickness direction of the optical recording medium 10. As shown in FIG. 1, when one light beam obtained by splitting by the beam splitter 26 irradiates one hologram pattern 12 of the optical recording medium 10, as shown in FIG.
Second-order transmitted diffracted light and two first-order transmitted diffracted lights corresponding to the second-order diffracted light are obtained, and a reproduced image is obtained by the two first-order diffracted lights. In FIG. 2, the dimensions in the X-axis direction and the Y-axis direction of two reproduced images obtained respectively by the two first-order diffracted lights are represented by e1 and e2, respectively. In the illustrated example, light is transmitted through the optical recording medium 10 to obtain transmitted diffracted light. However, if a reflection film is provided on the hologram pattern 12 of the optical recording medium 10 and it is designed to reflect incident light, Diffracted reflected light can be obtained instead of transmitted light. Here, the relationship between the diffraction angle θ and the irradiation wavelength λ is expressed by the above-described equation (1).

Here, a design example in the case where the beam splitter 26 is constituted by a diffraction grating will be described. The diffraction grating used as the beam splitter 26 is called a spectral diffraction grating to distinguish it from the hologram pattern diffraction grating. It is assumed that the spectral diffraction grating is made of a linear grating having a pitch α. The diffraction angle θ0 of this spectral diffraction grating
Can be expressed as: diffraction angle θ0 = used wavelength λ / grating pitch α. Now, the CGH interval p in the Y-axis direction on the base
Where p = 1 mm and the distance between the spectral diffraction grating 26 and the hologram pattern (CGH) 12 is 10 mm, θ0 = 1/10 = 0.1 rad.

Here, assuming that the used wavelength λ is λ = 780 nm, a diffraction grating pitch α = 7.8 μm is obtained. The direction of the diffraction angle is made to coincide with the Y-axis direction.

Another design example in which the beam splitter 26 is constituted by a diffraction grating will be described. Spectral diffraction grating 2
6 and the hologram pattern (CGH) 12 have a distance of 2
Assuming 8 mm, θ0 = 1/28 = 0.36 rad.

Here, assuming that the used wavelength λ is λ = 780 nm, a diffraction grating pitch α = 22 μm is obtained. The direction of the diffraction angle is made to coincide with the Y-axis direction.

The hologram pattern (CG shown in FIG. 1)
H) The relationship between 12 and the imaging surface can be understood as the relationship between the optical recording medium according to the present invention and the light receiving surface (imaging surface) of the reader (reader). FIG. 3 is a diagram schematically showing an overall configuration of one embodiment of an information reading apparatus for an optical recording medium according to the present invention. 3 reads and reproduces information recorded as a hologram pattern 12 from the card-shaped optical recording medium 10 shown in FIG. 4, but as shown in FIG. When the patterns 12 are arranged in a straight line in a plurality of rows, the optical recording medium 10 is conveyed linearly and information is sequentially read. On the other hand, the optical recording medium is CD, CD-R
In the case of a disk shape such as an OM or a DVD, the hologram pattern is arranged concentrically or spirally, so that the information is sequentially read by rotating the optical recording medium. In the following description, an example is described in which the optical recording medium is a card type and the hologram patterns are linearly arranged in one or more rows.

In the information reading apparatus for an optical recording medium shown in FIG. 3, a card-shaped optical recording medium 10 of a business card size is conveyed at a constant speed in a reading apparatus 22, and moves linearly as indicated by an arrow in the figure. I do. In the example of the optical recording medium 10 of FIG. 4, a plurality of hologram patterns 12 are arranged three by three in each row in the Y-axis direction to form a three-column pattern extending in the X-axis direction. In the example of the optical recording medium 10 in FIG.
A plurality of hologram patterns 12 are arranged in rows of five in the Y-axis direction, forming a pattern of five columns extending in the X-axis direction. 4 and 5, the dimension of each hologram pattern 12 in the X-axis direction and the Y-axis direction is k (that is, square), the pitch in the X-axis direction is q, and the pitch in the Y-axis direction is p. It is.

Next, referring to FIGS. 8 to 11, the manner of arrangement of reproduced images by diffracted light from the hologram pattern in the light receiving element in the information reading apparatus for an optical recording medium according to the present invention will be described. 8 to 11 show five lines in one line as shown in FIG.
9 shows an arrangement of a reproduced image in a case where hologram patterns are arranged. When five hologram patterns are arranged in one row, the beam splitter 26 in FIG.
In order to irradiate two light beams, one incident light beam is split into five light beams. That is, when the beam splitter 26 is configured by a diffraction grating, it is configured to use ± second-order diffracted light in addition to ± 1st-order diffracted light. Now, assuming that the five hologram patterns 12L-1 in the leftmost row in FIG. 5 are simultaneously irradiated by five light beams obtained by being split by the beam splitter 26, as shown in FIGS. A reproduced image in any one of the modes is obtained.

FIG. 8 shows an example in which two images 121A and 12A of two first-order diffracted lights are projected pointwise with respect to projected portions 111 to 115 of the 0th-order diffracted light from each hologram pattern 12.
1B, 122A, 122B... 125A, 125B are arranged. That is, the diffracted light from 12-1 in the hologram pattern 12L-1 on the leftmost row in FIG. 5 projects the projection part 111 of the 0th-order diffracted light and two images 121A and 121B symmetrical with respect to this. . The same applies to the other hologram patterns 12-2 to 12-5. As a result, as shown in FIG. 8, a total of five images reproduced by the + 1st-order diffracted light are arranged in a line, and the images reproduced by the -1st-order diffracted light are A total of five are arranged in one line. 8 to 11, f1 is a distance from the projected portion 111 of the 0th-order diffracted light to the center of the reproduced images 121A and 121B by the first-order diffracted light, and f2 is a reproduced image 121 by the adjacent first-order diffracted light.
A, 122A, 123A...

The example of FIG. 9 is an evolution of the example of FIG. 8, and the reproduced images 121A, 1
21B is a point object centering on the projected portion 111 of the 0th-order diffracted light, one of which (121A in this example) is intermediate between the reproduced images 122A and 123A by the other 1st-order diffracted light, and the 0th-order diffracted light is It is arranged in a portion close to the projection portions 112 and 113. This form of arrangement will be referred to as a rotational arrangement or a twist arrangement. The reason why the projection is performed as the rotational arrangement or the twist arrangement is because the configuration of the hologram pattern 12 has contents designed in advance. That is, the diffraction angles of the plurality of hologram patterns 12 and the arrangement angles of the recording portions thereof are determined in advance so that an image is formed at a predetermined position in the two-dimensional plane of the light receiving surface. In the example of FIG. 8, a one-dimensional diffraction grating in which all hologram patterns are diffracted one-dimensionally may be used. In the example of FIG. 9, two outer hologram patterns (in FIG. Patterns 12-1 and 12
-5) is a two-dimensional diffraction grating that diffracts two-dimensionally, and the other three (in FIG. 5, hologram patterns 12-2 to 12-12).
-4) is a one-dimensional diffraction grating that diffracts one-dimensionally.

FIG. 10 is a modification of FIG. 9, and shows the reproduced images 121A, 1A by the rotational arrangement by the first-order diffracted light in FIG.
21B is a point object centering on the projected portion 111 of the 0th-order diffracted light, one of which (121A in this example) is intermediate between the reproduced images 122A and 123A by the other 1st-order diffracted light, and the 0th-order diffracted light is Seen from the projected portions 112 and 113, the images are arranged outside the reproduced images 122A and 123A by the first-order diffracted light. 9 and 10, f3 is the distance from the projected portion 111 of the 0th-order diffracted light to the center of the reproduced images 121A and 121B that are rotationally arranged by the 1st-order diffracted light.

FIG. 11 is a modification of FIG. That is, FIG. 8 shows five hologram patterns 12 in one row in FIG.
FIG. 9 shows two rows adjacent to each other in FIG. 5, that is, a total of ten hologram patterns 12L-1 and 12L-2, which are obtained by irradiating L-1 simultaneously. Simultaneous irradiation is performed to obtain these reproduced images. As can be seen from a comparison between FIG. 8 and FIG. 11, ten reproduced images similar to the ten generated images obtained in FIG. 8 are mutually shifted in the X-axis direction so as not to overlap. . In FIG. 11, hl is the distance between the line connecting the bright spots of the hologram pattern 12L-1 due to the zero-order diffracted light and the line connecting the bright spots of the hologram pattern 12L-2, that is, the shift distance.

Next, specific examples of the respective examples shown in FIGS. 8 to 10 will be described. It is assumed that the optical system shown in FIGS. 1 to 3 is used and a recording medium in which five CGHs are arranged in one row shown in FIG. (In the case of FIG. 8) Specific dimensions <Condition 1> λ = 780 nm p = 1 mm θ0 = 0.1 rad θ1 = 0.384 rad d1 = 10 mm θe1 = 0.1 rad (pp) θe2 = 0.1 rad (pp)

<Condition 1-1> d2 = 12 mm f2 = (d1 + d2) θ0 = (10 + 12) * 0.1 =
2.2mm e1 = θe1 * d2 = 0.1 * 12 = 1.2mm e2 = θe2 * d2 = 0.1 * 12 = 1.2mm f1 = θ1 * d2 = 0.384 * 12 = 4.61mm Note Pattern Interval ratio = (f2-e2) / e2 =
0.83

<Condition 1-2> d2 = 20 mm f2 = (d1 + d2) θ0 = (10 + 20) * 0.1 =
3mm e1 = θe1 * d2 = 0.1 * 20 = 2mm e2 = θe2 * d2 = 0.1 * 20 = 2mm f1 = θ1 * d2 = 0.384 * 20 = 7.68mm Note Pattern interval ratio = (f2- e2) / e2 =
0.50

<Condition 2> λ = 780 nm p = 1 mm θ0 = 0.036 rad θ1 = 0.384 rad d1 = 28 mm θe1 = 0.1 rad (pp) θe2 = 0.1 rad (pp)

<Condition 2-1> d2 = 12 mm f2 = (d1 + d2) θ0 = (28 + 12) * 0.03
6 = 1.44 mm e1 = θe1 * d2 = 0.1 * 12 = 1.2 mm e2 = θe2 * d2 = 0.1 * 12 = 1.2 mm f1 = θ1 * d2 = 0.384 * 12 = 4.61 mm Note: Pattern interval ratio = (f2-e2) / e2 =
0.20

<Condition 2-2> d2 = 20 mm f2 = (d1 + d2) θ0 = (28 + 20) * 0.03
6 = 1.87mm e1 = θe1 * d2 = 0.1 * 20 = 2mm e2 = θe2 * d2 = 0.1 * 20 = 2mm f1 = θ1 * d2 = 0.384 * 20 = 7.68mm Note Pattern interval ratio = (F2-e2) / e2 =
-0.065 (overlap)

(In the case of FIG. 9) As shown in FIG.
When the number of CGH patterns is imaged, the aspect ratio (aspect ratio) of the standard TV CCD element is extremely different.
It becomes difficult to effectively use the element. Therefore, in order to adapt to the normal aspect ratio of 4: 3 or the high-vision aspect ratio of 16: 9, the above-described rotation arrangement is performed. In this example, two C
The GH pattern is rotated and moved. The condition in the case of FIG. 9 is calculated using FIG. 12 based on the condition 2-1 in the description of FIG.

The distance between adjacent CGHs after the movement is
It is set to 1.4 mm similarly to the interval. Note a = 1/2 * e2 b = f1-e1 c = 2 * f2 d = f1

Now, a: = 0.7, b: = 3.2,
Assuming that c: = 2.8, when the diffraction angle of the CGH that is not rotationally arranged is θ3, θ3 = tan ⁻¹ (ca) /b=0.807563.
(Rad) = 33.3 degrees.

F3 = (b ² + (ca) ² ) ^1/2 = 3.82753 The new diffraction angle θ4 is θ4 = tan ⁻¹ f / d = 0.
30895 (rad) = 17.7 degrees is obtained. Therefore, it is understood that the CGH having a diffraction angle of 17.7 degrees may be arranged by rotating it by 33.3 degrees. The right CG
H rotates left and CGH on the left rotates right.

(In the case of FIG. 10) In the same manner as above, the calculation is performed using FIG. Note a = 1/2 * e2 b = f1 + e1 c = 2 * f2 d = f1 θ3 = tan ⁻¹ (ca) /b=0.328 (rad)
= 19.3 degrees f3 = (b * b + (ca) **) ^1/2 = 12.6 θ4 = tan ⁻¹ (f3 / d2) = 0.789 (rad)
= 46.4 degrees

From the above, using CGH of about 1 μ pitch,
The CGH having a diffraction angle of 46.4 degrees is arranged by being rotated right or left by 12.6 degrees.

(Case of FIG. 11) For the case of FIG. 11,
This will be discussed with reference to the schematic diagram of FIG. The diffraction angle θ5 of the spectral diffraction grating 26, the spectral diffraction grating 26 and the recording medium (CGH1
2) distance d1 between 10, recording medium (CGH12) 10
The distance d2 between the image sensor 20 and the light receiving surface of the image sensor 20, the pitch q of the CGH in the X-axis direction, and the shift distance h1 on the light receiving surface have the following relationship.

Θ5 * d1 = q θ5 * (d1 + d2) = h1

Using this relationship, it is possible to design the optical recording medium 10 and an information reading apparatus for the optical recording medium that is compatible with the optical recording medium 10.

Next, the light source 16 by the beam splitter 26
The spectroscopy operation of the light beam from the light source will be described with reference to FIG.
When a diffraction grating is used as the beam splitter 26, incident light having a wavelength λ is θ = λ / p (p is the pitch of the diffraction grating).
Given by That is, the quantity of high-order diffracted light depends on the thickness and shape of the diffraction grating, but the diffraction angle depends on the pitch. The diffraction plane is a plane orthogonal to the diffraction grating plane, and diffracts at the above angle. That is, in the case where the diffraction gratings are arranged one-dimensionally, in FIG. 15 which is a schematic diagram, if the gratings are arranged in a direction perpendicular to the paper surface, an image is formed on the plane of the paper surface by diffraction. If the diffraction grating is parallel to the plane of the drawing, the diffracted light forms an image on a plane perpendicular to the plane of the drawing. For this reason, if the diffraction grating is arranged on the same plane in both directions parallel to and perpendicular to the plane of the drawing, the diffracted light is similarly two-dimensionally diffracted. FIG. 22, FIG.
Reference numeral 3 shows a state in which the diffraction direction can be selected to an arbitrary direction on a two-dimensional plane by rotating (twisting) the diffraction grating. That is, FIG. 22 shows that the lattice direction of the CGH 12 is the up-down direction, and shows how the light is diffracted in a direction perpendicular to this lattice.
2 shows a state in which the transmitted diffracted light transmitted through the CGH 12 rotated from the state 2 is diffracted in a direction orthogonal to the grating. That is, by rotating the CGH 12 about the optical axis of the incident light, the diffraction direction is rotated by the same angle. It should be noted that the arrangement direction of the imaging positions of the CGH 12 and the diffracted light is always kept parallel.

A diffraction grating applied to the beam splitter 26, that is, a diffraction grating that diffracts on a plane is preferable as a spectral diffraction grating, but a two-dimensional diffraction grating called CGH is configured by performing complicated calculations. . Here, the simple principle of CGH will be described.
m, and when this ray is incident on the CGH, the point object is focused on the 0th-order diffracted light indicated by the black point in FIG.
At one location, multiple diffraction spots occur within a 0.1 rad square.

FIG. 17 is a schematic diagram of CGH, and FIG.
In order to obtain diffraction centering on the 0.384 rad position from the 0th order light as shown in FIG. 2, the basic pitch p of the diffraction grating is 2 μm, but in order to obtain a change of 0.1 rad, the diffraction angle Becomes 0.334 to 0.434 rad,
The pitch p changes between 2.34 μm and 1.80 μm. In FIG. 16, the diffraction angle in the vertical direction is 0.
In order to obtain this diffraction, the grating shape of the diffraction grating is changed every 16 μm at a pitch pv in the longitudinal direction of the grating. In the actual design, the CGH shape takes a more complicated shape depending on the required pattern of the diffracted light, but basically has the configuration shown in the schematic diagram of FIG.

FIG. 18 is a perspective view of a preferred embodiment of the information reading apparatus for an optical recording medium according to the present invention, as viewed from below the optical recording medium 10. The light beam emitted from the light source 16 is divided into a plurality of light beams by the diffraction grating 26 as a beam splitter, and then the light beam forming plate 70 having a pinhole is provided.
A passes through the pinhole and enters the hologram pattern 12 provided on the optical recording medium 10. Optical recording medium 10
Are provided with a plurality of rows of hologram patterns 12, and reflected and diffracted light reflected therefrom is projected onto a light receiving surface of the image sensor 20 and received.

FIG. 19A is a plan view showing the structure of the light beam shaping plate 70A. The light beam shaping plate 70A has a pinhole 72 as a circular through hole. FIG. 19B is a plan view showing the structure of another light beam shaping plate 70B, in which a pin hole 74 as an elliptical through hole is provided in the light beam shaping plate 70B. This pinhole 72, 7
Depending on the shape of the light beam 4, the light beam can be formed into a conical shape, a long conical shape, or arbitrarily set.

FIGS. 20 and 21 are perspective views showing the specific structure of the recording medium transport device inside the information reading device for optical recording media. The transport device 48 has a substrate section 80 on which the optical recording medium 10 is placed, and the substrate section 80 has two shafts 82 and 8.
4 is attached to a stationary part (not shown) so as to be movable in the Y-axis direction (the short direction of the optical recording medium 10) in the figure. The shaft 86 is driven to rotate by a motor (not shown) driven by receiving an output signal of a conveyance speed control circuit (not shown), and the coaxial roller 88 is rotated by friction with the surface of the optical recording medium 10. The optical recording medium 10 is driven in the X-axis direction (longitudinal direction). FIG. 20 shows the optical recording medium 10.
2 shows the state of driving in the X-axis direction. At the end of the substrate portion 80, teeth 94 meshing with gear teeth are provided.
The rotational force of 0 is transmitted to the teeth 94 via the gear assembly 92, so that the substrate section 80 is driven in the Y-axis direction. FIG. 21 shows how the optical recording medium 10 is driven in the X-axis direction. If the photodetector 30 (not shown) detects the mechanical variation and the vertical shift of the hologram pattern 12 and performs feedback control of the motor 90, these variations and the vertical shift can be corrected.

[0052]

As described above, according to the present invention, when a plurality of hologram patterns are simultaneously irradiated with light beams, the transmitted or reflected diffracted light is formed at a predetermined position in a predetermined two-dimensional plane. Since the diffraction angles of a plurality of hologram patterns and the arrangement angles of the recording portions are determined in advance so as to form an image, when reading information from an optical recording medium, the efficiency is improved by simultaneously irradiating the plurality of hologram patterns. Readout can be realized. Further, in the information reading apparatus for an optical recording medium of the present invention, a spectroscopic means for dispersing a light beam from a light source into a plurality of light beams and a recording medium in which a plurality of diffraction gratings are formed as a hologram pattern and arranged two-dimensionally. When the light beam condensed by the optical unit is irradiated, the reflected light diffracted light or the transmitted diffracted light is received, and the unit for reading the hologram pattern and the recording medium are transported in a direction orthogonal to the spectral direction by the spectral unit. The provision of the means makes it possible to read out a large amount of recording data recorded as a hologram pattern at high speed and efficiently.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a diffraction state of transmitted light when a plurality of hologram patterns of an optical recording medium according to the present invention are irradiated with a light beam obtained by splitting light from a light source.

FIG. 2 is a diagram showing a state in which light rays diffracted by one hologram pattern form images at a plurality of locations on a two-dimensional plane.

FIG. 3 shows an information reading apparatus for an optical recording medium according to the present invention;
It is a figure which shows the whole structure of one Embodiment typically.

FIG. 4 is a plan view of an example in which the optical recording medium according to the present invention is embodied as a business card size card.

FIG. 5 is a plan view of another example in which the optical recording medium according to the present invention is embodied as a business card size card.

FIG. 6 is a block diagram schematically illustrating a method of manufacturing an optical recording medium master, a method of recording information on an optical recording medium, an apparatus and a method of manufacturing an optical recording medium.

7A is a diagram showing a procedure for obtaining a hologram interference fringe pattern from a two-dimensional image, and FIG. 7B is a photograph showing an example of a hologram interference fringe used in the present invention.

FIG. 8 is a schematic diagram of a reproduced video obtained from an example of the optical recording medium of the present invention.

FIG. 9 is a schematic diagram of a reproduced image obtained from another example of the optical recording medium of the present invention.

FIG. 10 is a schematic diagram of a reproduced video obtained from another example of the optical recording medium of the present invention.

FIG. 11 is a schematic diagram of a reproduced video obtained from another example of the optical recording medium of the present invention.

12 is a schematic diagram illustrating a method for designing the optical recording medium of the example of FIG.

13 is a schematic diagram illustrating a method for designing the optical recording medium of the example of FIG.

14 is a schematic diagram illustrating a method for designing the optical recording medium of the example of FIG.

FIG. 15 is a schematic diagram illustrating a mode of spectral separation by a diffraction grating.

FIG. 16 is a schematic diagram showing an arrangement of a reproduced image obtained by diffracted light by CGH.

FIG. 17 is a schematic diagram showing a design method of CGH.

FIG. 18 is a perspective view of a preferred embodiment of the information reading apparatus for an optical recording medium according to the present invention as viewed from below the optical recording medium.

FIG. 19 is a plan view showing two examples of a light beam forming plate provided with a pinhole used to obtain a light beam having a desired shape.

FIG. 20 is a perspective view showing a state in which the optical card is driven in the longitudinal direction by a device for driving the optical card in the longitudinal direction (X-axis direction) and in the transverse direction (Y-axis direction). is there.

FIG. 21 is a perspective view showing a state in which the optical card is driven in the transverse direction by a device for driving the optical card in the longitudinal direction (X-axis direction) and the transverse direction (Y-axis direction). It is.

FIG. 22 is a perspective view showing that the diffraction direction can be selected in an arbitrary two-dimensional plane by rotating (twisting) the diffraction grating, together with FIG. 23.

23 is a perspective view together with FIG. 22 showing how a diffraction direction can be selected to an arbitrary direction on a two-dimensional plane by rotating (twisting) and arranging the diffraction grating.

[Explanation of symbols]

10, 10A Optical recording medium (card) 12 Recording part (diffraction grating, hologram pattern, CG
H) 16 light source (laser diode) 18 two-dimensional plane (corresponding to light receiving surface of image sensor) 20 image sensor (CCD element) 22 information reading device of optical recording medium 26 spectral diffraction grating as beam splitter 48 transport device 70A 70B Light beam forming plate (shielding means) 80 Substrate unit 82, 84, 86 Shaft 88 Roller 90 Motor 92 Gear assembly 94 Tooth

Continuation of the front page (72) Inventor Kenji Narusawa 3-12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture F-term (reference) 2C005 HB01 HB04 JA18 LB15 2K008 AA04 AA13 CC01 CC03 FF07 FF27 HH19 HH28 5B035 AA02 BB00 BB05 5B072 AA01 CC02 CC35 DD00 LL00 LL12 LL19

Claims (4)

[Claims] 1. An optical recording medium on which a plurality of hologram patterns are recorded, wherein when the plurality of hologram patterns are simultaneously irradiated with light beams, the transmitted diffraction light or the reflected diffraction light is within a predetermined two-dimensional plane. An optical recording medium, wherein diffraction angles of the plurality of hologram patterns and arrangement angles of recording portions thereof are determined in advance so as to form an image at a predetermined position. 2. The plurality of hologram patterns,
2. The optical recording medium according to claim 1, wherein at least one of the optical recording media is a two-dimensional diffraction grating that diffracts two-dimensionally, and the other is a one-dimensional diffraction grating that diffracts one-dimensionally. 3. At least five hologram patterns are recorded on a straight line as the plurality of hologram patterns, image forming portions of first three-dimensional diffracted light of three central hologram patterns are arranged in a line, and two holograms at both ends are provided. The respective image-formed portions of the pattern by the first-order diffracted light are closer to or farther from the image-formed portion of the 0th-order diffracted light than the portions of the central three hologram patterns arranged in a row in the image-formed portion of the first-order diffracted light. The respective image-formed portions of the central three hologram patterns arranged in a line and of the first-order diffracted light of the three central hologram patterns and the respective image-formed portions of the two hologram patterns at both ends of the first-order diffracted light have a predetermined aspect ratio. The optical recording medium according to claim 1, wherein the optical recording medium is configured to fit within a rectangle. 4. A light source that emits light of a predetermined wavelength, a light splitting unit that splits a light beam from the light source into a plurality of light beams, and a plurality of diffraction gratings are formed as a hologram pattern;
When a light beam condensed by the optical means is applied to a two-dimensionally arranged recording medium, the reflected light diffracted light or the transmitted diffracted light is received, and a hologram pattern of the diffraction grating is read; Means for transporting the recording medium in a direction orthogonal to the direction of dispersion by the dispersion means.