JPH08272923A - Diffraction grating type information recording medium - Google Patents

Abstract

PURPOSE: To accurately record a large amount of information without generating any quantum error by setting the length of a diffraction grating array being a recording unit to be less than the diameter of spot beam and composing the diffraction grating array of diffraction grating bells which continuously vary in grating stripe interval. CONSTITUTION: When a part of a recording track 1 is expanded, three kind of diffraction grating arrays (a)-(c) are present in the scanning direction (x) of the spot beam. The respective grating arrays (a)-(c) have length less than the diameter 3 of the read spot beam and one of them (diffraction grating array (a)) is regarded as one recording unit 2. The direction where the diffraction gratings are arrayed and the direction meaning the length less than the beam diameter, are (x) direction. In the recording unit 2, plural kinds of diffraction grating cells which change in grating stripe interval, cell by cell, are arranged. For example, four kind of diffraction grating cells are arrayed in the recording unit 2 and the array direction of grating stripes formed on the respective cells is fixedly the (x) direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention writes information by optically reading the information as a diffraction angle change from a diffraction grating band (recording track) in which arbitrary information is written as a spatial frequency distribution of a diffraction grating array. The present invention relates to an information recording medium of a system for reproducing stored information.

[0002]

2. Description of the Related Art One-dimensional information (for example, a bar code) or two-dimensional information (for example, a Carla code) recorded on a two-dimensional plane is holographically recorded as an image, and an image reading sensor (for example, CCD). ), And decoding the image to retrieve the recorded information for reproduction is known.

[0003]

However, in the method of the above-mentioned known art, since information is digitized and recorded, a large amount of information is required when handling analog information. In addition, it is difficult to obtain the information recording density required to record analog information by the above method, and it is necessary to perform digitization, which causes a quantum error, which is not preferable. Further, in reproducing the recorded information, an information processing device including a D / A converter and the like is required, resulting in a large circuit cost and a complicated practical problem.

Further, there is a possibility that the information recorded during the reading may not be read correctly due to the variation of the wavelength of the light irradiated for reading or the warp of the support, which is avoided. Therefore, a very stable sensor and a support are required, and again, there is a problem that the cost becomes large and it is complicated in practical use.

The present invention solves the above-mentioned problems, and any analog information (or digital information) to be recorded is continuously written and recorded as it is in the diffraction grating band as a spatial frequency distribution and is written. It is an object of the present invention to provide a diffraction grating type information recording medium that enables information to be read out optically by changing the diffraction angle.

Even in the recording medium having the above specifications, when the recorded information is read out, if the length of the diffraction grating array serving as a recording unit is equal to or larger than the spot beam diameter for reading, the beam is scanned. Accordingly, since only one diffracted light (information signal) whose emission angle continuously changes is generated, there is a problem in that it is inappropriate for multiplexing or encrypting information to be recorded.

Another object unique to the present invention is to provide a diffraction grating type information recording medium which can solve the above problems and can multiplex or encrypt information to be recorded.

[0008]

In order to achieve the above object, in the present invention, the length of the diffraction grating array serving as a recording unit is set to be equal to or smaller than the spot beam diameter for reading, and the diffraction grating array has a grating fringe spacing. Continuously changing diffraction grating cells, or a collection of multiple types of diffraction grating cells with different grating fringe spacing,
Compose by.

That is, according to the first aspect of the present invention, a diffraction grating band formed by continuously arranging diffraction grating rows is used as a recording track, and arbitrary information to be recorded can be written as a spatial frequency distribution of the diffraction grating row. A diffraction grating type information recording medium which reproduces written information by optically reading the distribution as a change in diffraction angle, wherein the diffraction grating array has a length equal to or smaller than a spot beam diameter for reading. As a recording unit, diffraction grating cells with varying grating fringe spacing are arranged in the diffraction grating array, and the diffraction grating array is formed by continuously arranging the diffraction grating array in a one-dimensional direction. It is characterized by

According to a second aspect of the present invention, a diffraction grating array formed by continuously arranging the diffraction grating cells in the array direction of the grating stripes is used as a recording unit, and the diffraction grating array is continuously arranged in the same direction as the array direction of the grating stripes. The diffraction grating type information recording medium according to claim 1, wherein the diffraction grating band is constituted by

According to a third aspect of the present invention, the recording unit is a diffraction grating array formed by continuously arranging the diffraction grating cells in the arrangement direction of the grating stripes, and the diffraction grating array is continuously arranged in a direction different from the arrangement direction of the grating stripes. The diffraction grating type information recording medium according to claim 1, wherein the diffraction grating band is constituted by

The invention according to claim 4 is characterized in that a plurality of types of diffraction grating cells having a constant grating fringe spacing in the same cell are arranged in a diffraction grating array serving as a recording unit. It is the described diffraction grating type information recording medium.

According to a fifth aspect of the present invention, a diffraction grating array in which the diffraction grating cells are continuously arranged in a direction different from the array direction of the grating stripes is used as a recording unit. It is a type information recording medium.

According to a sixth aspect of the present invention, the grating fringe spacing is continuously changed and written as a continuous distribution of spatial frequencies within the diffraction grating array, so that the grating grating array is continuously arranged along the arrangement direction. The diffraction grating type information recording medium according to claim 2, wherein the written analog information is reproduced by optically reading it as a change in the diffraction angle.

According to a seventh aspect of the present invention, the grating fringe spacing is discretely changed and written as a stepwise distribution of spatial frequencies in the diffraction grating array, so that the grating cells are discretely distributed along the arrangement direction of the diffraction grating cells. 5. The diffraction grating type information recording medium according to claim 3 or 4, wherein the written digital information is reproduced by optically reading as a change in the diffraction angle.

According to an eighth aspect of the present invention, the grating fringe spacing is discretely changed and written as a stepwise distribution of the spatial frequency in the diffraction grating array, so that the diffraction grating cells are discretely distributed along the arrangement direction. It is possible to perform a pseudo multi-channel pseudo-change due to the fact that the grating fringe spacing formed in the diffraction grating cells at the corresponding positions in the adjacent diffraction grating rows changes continuously in close proximity while being optically read as a large change in diffraction angle. The diffraction grating type information recording medium according to claim 3 or 4, which reproduces analog information.

As an example of how to write information to the information recording medium of the present invention, arbitrary analog information to be recorded is converted corresponding to a diffraction angle, and a space corresponding to the diffraction angle is formed in a diffraction grating band as a recording track. The frequency distribution is continuously recorded as a fine diffraction grating array.

As described above, the analog information is written as the spatial frequency distribution of the diffraction grating of the diffraction grating band. To read this information, light of a single wavelength or a non-single wavelength is emitted from a light source while moving the diffraction grating band at a predetermined speed, and the diffracted light emitted from the illuminated portion is incident on the head side. Detect the diffraction angle. Based on this diffraction angle, the original analog information can be demodulated and reproduced.

[0019]

Since the recording unit is composed of the diffraction grating array having a length equal to or smaller than the diameter of the spot beam for reading, when the spot beam is irradiated on the recording track during reading, a plurality of diffraction grating cells in the recording unit are used. Diffracted light is generated and emitted.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. 1, 8 and 9 are plan views showing an embodiment of a diffraction grating type information recording medium, FIG. 2 is a diagram showing an example of arbitrary analog information to be recorded, and FIG. 3 corresponds to the analog information of FIG. Spatial frequency-lattice position diagram, FIG. 4 is a diagram showing the relationship between spatial frequency and diffraction angle, FIG. 5 is a schematic diagram showing a recording state of multi-valued digital information, and FIG. 6 is a binary digital information recording state. It is a schematic diagram.

First, the principle of recording / reproducing analog information in the present invention will be described. As shown in FIG. 2, a curve A representing the time change of the voltage output from a device is given as analog information. Of course, the analog information provided may be arbitrary. When a light beam having a wavelength λ is vertically incident (incident angle 0 °), the spatial frequency f is the reciprocal 1 / p of the grating pitch p as shown in FIG. Lattice pitch = λ / sin θ (θ; diffraction angle λ; wavelength)

In other words, the smaller the grating pitch and the denser, the larger the diffraction angle. Therefore, the spatial frequency is obtained corresponding to the diffraction angle as shown in the graph. As described above, the voltage-time diagram shown in FIG. 2 is replaced with the spatial frequency f-lattice position diagram shown in FIG. This spatial frequency −
The diffraction grating information recording medium 10 shown in FIG. 1 is created by the diffraction grating creating machine based on the grating position diagram.

That is, according to the spatial frequency distribution shown in FIG. 3, the diffraction grating array 3 is written on the recording track 1, and its moving direction corresponds to the grating position. As the diffraction grating creating machine, an exposure apparatus using a laser, an electron beam drawing apparatus, and other fine processing apparatus having a function of creating a diffraction grating are used. As described above, arbitrary analog information can be written in the recording track as a diffraction grating band composed of a diffraction grating array.

FIG. 5 shows multilevel digital information recorded on the recording track 1a of the diffraction grating type information recording medium.
Since the multi-valued digital information is replaced with multi-valued spatial frequency information f ₁ ... F _5, etc., it can be easily recorded as in the recording method of the analog information. That is, the track may be divided into segments, and the diffraction grating array may be formed at a grating pitch determined by a predetermined spatial frequency assigned to each segment.

In FIG. 6, binary (0 or 1) digital information is recorded on the recording track 1b of the diffraction grating type information recording medium. That is, the diffraction grating array may be subdivided along the recording track into bits, and the binary digital information may be formed at the grating pitch of the spatial frequency distribution for each bit unit.

In the present invention, in any case (multilevel digital information / binary digital information), a plurality of diffraction grating cells are arranged within the range of the spot beam diameter for reading, and one recording unit (diffraction grating array). And When recording / reproducing arbitrary analog information, instead of arranging a plurality of cells in one recording unit, instead of arranging a diffraction grating array, a diffraction grating whose grating fringe spacing changes continuously is arranged in the recording unit. To do.
(See Fig. 10)

Various types of information recording media provided with recording tracks (diffraction grating bands) in which the diffraction grating rows are continuously arranged will be described below. In FIG. 1, when a part of the recording track 1 of the diffraction grating type information recording medium 10 is enlarged, three kinds of diffraction grating rows (a to c) are provided in the part.
Exist in the scanning direction by the spot beam (X direction in the figure).

Each diffraction grating array (a to c) has a reading spot beam diameter of 3 or less, and one of them (diffraction grating array a) is a recording unit 2. The direction in which the diffraction gratings are arranged and the direction meaning a length equal to or smaller than the beam diameter are the X direction (scanning direction by the spot beam) shown in FIG.

In the recording unit 2, a plurality of types of diffraction grating cells whose grating fringe spacing changes for each cell are arranged.
In the figure, four types of diffraction grating cells are arranged in five areas in the recording unit 2. Although not shown, the array direction of the lattice stripes formed in each cell is constant in the X direction.
(Corresponding to claim 2)

On the other hand, in the embodiment shown in FIG. 8, the diffraction grating cells are continuously arranged in the direction orthogonal to the scanning direction (X direction) by the spot beam. Although not shown,
The array direction of the lattice stripes formed in each cell is constant in the direction orthogonal to the X direction. (Corresponding to claim 3)

In the case of the figure, the diffracted light corresponding to the type of cell is generated and emitted in the direction orthogonal to the scanning direction in response to the scanning in the X direction by the spot beam. In the figure, 5 diffracted lights are always generated and emitted, so
Channel information can be recorded / played back.

On the other hand, as shown in FIG. 9A, a recording unit may be a diffraction grating array in which diffraction grating cells are continuously arranged in a direction different from the array direction of the grating stripes. Also in this case,
Since the direction of the grating stripes in the diffraction grating array is constant, the direction in which the diffracted light is generated and emitted according to the scanning by the spot beam (when the diffraction grating array is viewed from directly above) is constant. Only the emission angle changes according to the interval.
(Corresponding to claim 5)

Therefore, according to FIGS. 8 and 9, the light receiving sensor can be arranged in a direction different from the conveying direction of the recording medium (scanning direction by the spot beam), and the degree of freedom of the sensor arrangement is secured.

Diffraction grating cells (diffraction grating arrays) constituting a recording unit are arranged in a grid pattern as shown in recording unit d in FIGS. 9B and 10A and recording unit b in FIG. 10C. It may be a diffraction grating cell whose interval is continuously changed.
In this case, it is suitable for a method of converting arbitrary analog information to be recorded in correspondence with the diffraction angle. (Corresponding to claim 6)

Further, as shown in FIGS. 5 and 6, a plurality of types of diffraction grating cells may be used, in which the lattice fringe spacing is constant in each cell and the lattice fringe spacing is different for each cell. This case is suitable for a system in which specific information is represented by the sum of reproduction information (a system for converting arbitrary digital information to be recorded in correspondence with a diffraction angle). (Corresponding to claim 4 and claim 7)

Further, as shown in FIG. 10B, the grating fringe spacing is discretely changed and written as a stepwise distribution of the spatial frequency within the diffraction grating array (recording unit),
Multi-channel (3 channels in the figure) by continuously changing the grating fringe spacing formed in the diffraction grating cells at the corresponding positions in the adjacent recording units.
It is also possible to record (and reproduce) pseudo analog information of. (Corresponding to claim 8)

The relationship between various types of recording tracks (diffraction grating band) and reproduction information (output waveform) is illustrated in FIG.

FIG. 7 shows the diffraction grating type information recording medium 1 described above.
It is explanatory drawing which shows the mode of the information reproduction by the reading light (incident light) 8 from 0 typically.

The information reproducing apparatus 30 includes a support 4 for supporting the diffraction grating type recording medium 10, a moving means (not shown) for moving the support 4 (or a light source described later) at a constant speed, and a moving diffraction grating. Light source 5 for irradiating a recording track of the type information recording medium 10 with incident light 8 and a diffraction grating type information recording medium 10
The head 6 for detecting the diffraction angle by receiving the diffracted light 21, 22, 23 (in this case, three types of diffraction grating cells in the recording unit) emitted from the irradiation area of, and the original information from the diffraction angle. It is composed of a decoder 7 for demodulating and reproducing.

As the light source 5, in addition to a laser light source which emits laser light of a single wavelength, a light source having a bright line spectrum which emits light of a non-single wavelength, a light source of white light, a light source outside the visible range such as X-rays, and a microwave. Radio waves, etc. are widely applicable. Further, as the head 6, when the light source is visible light, photodiodes or phototransistors arranged in a line,
A photomultiplier tube, a CCD, or those in which these are arranged in an array is applied, and when the light source is an X-ray, an X-ray camera is used, and when it is a microwave, an antenna or the like is applied.

For example, the diffraction grating type information recording medium 10 shown in FIG. 1 is fixed to the support 4, and the incident light 8 is emitted from the light source 5 while moving the support 4 at a predetermined speed, thereby sequentially irradiating. A plurality of diffracted lights are continuously emitted from the part and are received by the head 6.

The head 6 detects the diffraction angles of the diffracted lights 21, 22, 23 and sends a detection signal to the decoder 7. Decoder 7
Demodulates the voltage-time diagram based on the diffraction angle detection signal,
To play.

The information recording medium according to the present invention has, for example, a laminated structure in which a metal film or the like is formed on a transparent base material. A recording track is formed by drawing a diffraction grating array having a desired spatial frequency distribution on the metal film in a fixed direction by using a diffraction grating creating machine. The transparent substrate is processed into, for example, a card shape or a disk shape. An optical reading type ID card can be obtained by writing personal identification information or the like on a card type recording medium. If a spiral or concentric recording track is formed on a disk-shaped recording medium and an analog audio signal or an analog video signal is written along the recording track, a novel optical disk replacing the conventional laser disk can be obtained.

[0044]

According to the present invention, the following remarkable effects are obtained. 1) Since analog information can be written as it is on a diffraction grating or the like, a large amount of information can be accurately recorded without causing a quantum error. 2) Since a signal processing device such as a D / A converter is unnecessary,
The circuit cost can be reduced. 3) Because information can be written and read optically,
There is no complexity in actual use. 4) Multivalued digital information and binary digital information can be recorded in the same manner, and the range of use can be expanded. 5) The problem of deterioration of reading accuracy due to external factors such as wavelength fluctuation of reading light and deformation of the support is solved. 6) A plurality of diffracted lights (information signals) whose emission angles are changed are constantly generated and emitted according to the irradiation of the reading beam, so that multi-channel information can be recorded, and information multiplexing and encryption are possible. It is suitable in order to achieve

[0045]

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of a diffraction grating type information recording medium.

FIG. 2 is a diagram showing an example of arbitrary analog information to be recorded.

FIG. 3 is a spatial frequency-lattice position diagram corresponding to the analog information of FIG.

FIG. 4 is an explanatory diagram showing a relationship between a diffraction angle and a spatial frequency.

FIG. 5 is an explanatory diagram showing an example of a diffraction grating array in which multivalued digital information is recorded.

FIG. 6 is an explanatory diagram showing an example of a diffraction grating array in which binary digital information is recorded.

FIG. 7 is an explanatory diagram schematically showing how information is reproduced.

FIG. 8 is a plan view of another embodiment of the diffraction grating type information recording medium.

FIG. 9 is a plan view of another embodiment of the diffraction grating type information recording medium.

FIG. 10 is an explanatory diagram showing a correspondence relationship between various recording media and reproduced information.

[Explanation of symbols]

 1 ... Recording track (diffraction grating band) 2 ... Recording unit (diffraction grating row) 3 ... Spot beam diameter for reading 4 ... Support 5 ... Light source 6 ... Head 7 ... Decoder 8 ... Read light (spot beam) 10 ... Diffraction grating type information recording medium 21, 22, 23 ... Diffracted light 30 ... Information reproducing device

Claims (8)

[Claims] 1. A diffraction grating band formed by continuously arranging diffraction grating arrays is used as a recording track, and arbitrary information to be recorded can be written as a spatial frequency distribution of the diffraction grating array, and the distribution is changed in diffraction angle. Is a diffraction grating type information recording medium for reproducing the written information by optically reading as a recording unit, and a diffraction grating array having a length equal to or smaller than a spot beam diameter for reading is used as a recording unit. , A diffraction grating cell having a varied grating fringe spacing is arranged, and the diffraction grating array is continuously arranged in a one-dimensional direction to form a diffraction grating band. Medium. 2. A diffraction grating array is formed by continuously arranging diffraction grating cells in the array direction of the grating stripes, and the diffraction grating array is continuously arranged in the same direction as the array direction of the grating stripes to form a diffraction grating band. The diffraction grating type information recording medium according to claim 1, characterized in that: 3. A diffraction grating array in which diffraction grating cells are continuously arranged in the array direction of the grating stripes is used as a recording unit, and the diffraction grating array is continuously arranged in a direction different from the array direction of the grating stripes to form a diffraction grating band. The diffraction grating type information recording medium according to claim 1, characterized in that: 4. A diffraction grating type information recording according to claim 1, wherein a plurality of types of diffraction grating cells having a constant grating fringe spacing in the same cell are arranged in a diffraction grating array serving as a recording unit. Medium. 5. A diffraction grating type information recording medium according to claim 1, wherein a diffraction grating array in which diffraction grating cells are continuously arranged in a direction different from the array direction of the grating stripes is used as a recording unit. 6. The grating fringe spacing is continuously changed and written as a continuous distribution of spatial frequencies in the diffraction grating array, so that the diffraction angle is optically changed as a continuous diffraction angle change along the arrangement direction of the diffraction grating array. The diffraction grating type information recording medium according to claim 2, wherein the written analog information is reproduced by reading the information. 7. A grating fringe spacing is discretely changed and is written as a stepwise distribution of spatial frequencies in a diffraction grating array, so that a discrete diffraction angle change along the arrangement direction of the diffraction grating cells is optically performed. 5. The diffraction grating type information recording medium according to claim 3, wherein the written digital information is reproduced by reading the information. 8. A grating fringe spacing is discretely changed and is written as a stepwise distribution of spatial frequencies in a diffraction grating array, so that the diffraction angle is optically changed as a discrete diffraction angle change along the arrangement direction of the diffraction grating cells. In addition, it is possible to reproduce multi-channel pseudo analog information because the grating fringe spacing formed in the diffraction grating cells at the corresponding positions in the adjacent diffraction grating rows changes continuously and simultaneously. 5. The diffraction grating type information recording medium according to claim 3 or 4.