JP2000260062A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an exact timing signal by reading a hologram pattern for timing formation on an optical recording medium during transportation. SOLUTION: On this optical recording medium, plural information CGHs 12 indicating information at a prescribed pitch in are arrayed in the transporting direction of the medium and plural control CGHs 13 for forming the timing signals to successively read the information CGHs 12 during transportation are arranged in the transporting direction of the medium. ON the control CGHs 13, two kinds of the hologram patterns varying in diffraction characteristics are arrayed in such a manner that the boundaries come into contact alternately in the transportation direction. The information CGHs 12 are so arranged that the centers thereof are aligned to the boundaries of the control CGHs 13. The length in the transportation direction of the control CGHs 13 is the same as the pitch of the information CGHs 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording medium on which a plurality of hologram patterns representing information are formed, and more particularly to an optical recording medium suitable for a prepaid card, a credit card, a certification card and the like.

[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.

Accordingly, the present applicant has already developed an optical recording medium in which a plurality of hologram patterns are arranged as CGH (computer generated hologram) on one substrate, and has applied for a patent (Japanese Patent Laid-Open No. 10-1436).
03 publication). In this optical recording medium, a plurality of hologram patterns representing information are two-dimensionally arranged along a plurality of rows in the X direction and a plurality of columns in the Y direction. In order to read recorded data from such an optical recording medium, the optical recording medium is conveyed in the X direction, and a plurality of light beams are simultaneously irradiated on a plurality of hologram patterns arranged in the Y direction, and the transmitted diffraction light or reflected light is reflected. The recorded data is read by a two-dimensional CCD from the pattern of the light beam projected by the diffracted light or the reproduced image projected.

However, in order to increase the data recording density, the CGH is configured to have a size of, for example, 100 to 300 μm square or smaller. Unless the read timing when the reflected diffracted light is imaged and read by the two-dimensional CCD is accurate, data cannot be read at high speed and efficiently. In addition, in prepaid cards and the like, there is a method of erasing data by destroying a predetermined hologram pattern by applying heat or hitting according to the amount of money used, but in this case, the timing of data erasure is precisely controlled. Therefore, simply controlling the erasing timing by relying on the outer diameter of the optical recording medium as in the related art has limited accuracy and has been a bottleneck for speeding up.

The applicant of the present invention has proposed a prior application (Japanese Patent Application No. 10-2300) in order to improve the reading accuracy of CGH.
No. 34) proposes a method of recording, on an optical recording medium, a control CGH for generating a timing signal for reading the information CGH in addition to the information CGH representing the information. FIG. 12 shows a conventional optical recording medium proposed in the earlier application. Here, X direction: transport direction of the optical recording medium (longitudinal direction of rectangular card, CGH row direction) Y direction: direction in which a plurality of CGHs in the column direction are read out simultaneously by the divided optical system (width direction of rectangular card, CGH column direction).

FIG. 12A shows a plurality of columns of information CGH12.
And one row of control CGHs 13A and 13B arranged in the X direction to generate a timing signal for reading the information CGH 12 in the X direction. The information CGH 12 and the control CGHs 13A and 13B are squares of the same size. Is formed. The control CGHs 13A and 13B have different diffraction characteristics and are arranged alternately in the X direction so that the boundaries are in contact. The information CGH12 has the control CGH at the center in the X direction.
They are arranged so as to coincide with the boundaries between 13A and 13B.

Then, light having a wavelength corresponding to the depth of the CGH is divided into a plurality of spot lights in the Y direction by the reading apparatus shown in FIG. 13, and each spot light is simultaneously conveyed in the X direction. When irradiated upward, diffracted light is generated from the information CGH 12 and the control CGH 13. The odd-numbered control C is controlled by the two light receiving elements 30A and 30B.
When the GH13A receives the diffracted light of the even-numbered control CGH 13B, the detection signal of the light receiving element 30A (FIG. 1) when the spot light is at the center position of the odd-numbered control CGH 13A.
2b) is maximized, and the detection signal (FIG. 12c) of the light receiving element 30B is minimized. In addition, even-numbered control C
When it is at the center of the GH 13B, the detection signal of the light receiving element 30A becomes minimum and the detection signal of the light receiving element 30B becomes maximum.

Accordingly, the difference d = bc is maximum when the control CGH 13A is at the odd-numbered position, is "0" when the control CGHs 13A and 13B are at the boundary, and is at the position of the even-numbered control CGH 13B. Sometimes the minimum sine curve (AC). Then, the sine curve is binarized at a zero crossing point, and the system clock is latched at the rising edge of the binarized signal, so that the exposure control signal e generated at each boundary of the control CGH (that is, at each center of the information CGH) is obtained. Can be generated. Therefore, as shown in FIG.
Is coincident with the center of information CGH12,
Exposure of the CCD imaging system (CCD 20, CCD element controller 36, video information processing circuit 38 shown in FIG. 13) can be started from the center of the information CGH 12. Further, the conveyance of the medium 10 in the X direction can be controlled (see FIG. 13).
The transfer speed control circuit 46 and the transfer device 48 shown in FIG.

FIG. 14 to FIG. 16 show another medium. In this medium, four types of control CGHs 13 are provided in order to obtain a reading timing in the X direction in which a reading error in the Y direction is absorbed.
A, 13B, 13C, 13D
It is recorded in the shape of a “field” of columns × 2 rows, which are repeatedly recorded in the X direction. Further, this control CGH 13 is set to Y
Information CGHs 12 are recorded while being arranged in the X direction so as to be sandwiched in the direction. Further, the boundaries of the control CGHs 13A and 13B with respect to the X direction, the control CGHs 13C and 13
The boundary of D and the center of information CGH12 match.

The four control CGHs 13A and 13
B, 13C and 13D are each a 2 × 2 light receiving element 30A
By calculating (A + C)-(B + D) by receiving light through 30D, it is possible to accurately obtain the reading timing in the X direction even if the spot light and the medium are shifted in the Y direction.

[0011]

In order to improve the recording density of CGH, improve the reading speed of CGH, and accurately read CGH, a plurality of CGHs arranged in the column (Y) direction are required. CGH (Control CGH13
And information CGH12), the readout optical system
It is necessary to simultaneously and accurately irradiate a plurality of light beams divided in each direction. Therefore, the spot light S
Is larger than the information CGH 12, the information CGH 12 and the control CGHs 13A and 13B have the same size.
Control CGH1 on both sides when located at the center of H13A
3B generates diffracted light, which makes it impossible to obtain accurate reading timing in the X direction.

In the method in which the medium is transported at a constant speed in the X direction and the control CGH is read to generate the exposure control signal e, the timing of the exposure control signal e is affected by the speed error and jitter of the medium transport system. Becomes inaccurate, so that the light beam is not accurately applied to the information CGH12,
There is a problem that an error in the stop position occurs when the information CGH 12 is read or the information CGH 12 is erased by stopping the conveyance of the medium at the designated position. .

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide an optical recording medium capable of reading a hologram pattern for generating timing on an optical recording medium being conveyed and generating an accurate timing signal. Aim.

[0014]

According to the present invention, in order to achieve the above object, the pitch of the first hologram pattern representing information and the length of the second hologram pattern for timing in the transport direction are made equal. It is. That is, according to the present invention, a plurality of first hologram patterns representing information are arranged at a predetermined pitch in a transport direction, and a timing signal for sequentially reading the plurality of first hologram patterns during transport is generated. In the optical recording medium in which a plurality of second hologram patterns are arranged in the transport direction, the second hologram pattern is such that two types of hologram patterns having different diffraction characteristics alternately in the transport direction and the boundaries contact. The first hologram pattern is arranged such that the center of the first hologram pattern in the transport direction coincides with the boundary of the second hologram pattern, and the length of the second hologram pattern in the transport direction is the first hologram pattern. An optical recording medium having the same pitch as the pattern is provided.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of an information reading device for an optical recording medium according to the present invention, FIG. 2 is an explanatory diagram showing a signal waveform according to a relationship between one control CGH and a spot diameter, and FIG. FIG. 4 is an explanatory diagram showing signal waveforms according to the relationship between the control CGH and the spot diameter, and FIG. 4 shows control Cs arranged alternately in the transport direction so that the boundaries contact each other.
Explanatory diagram showing a signal waveform according to the relationship between GH and spot diameter,
FIG. 5 is an explanatory diagram showing a signal waveform according to a relationship between a control CGH and a spot diameter arranged at a distance, FIG. 6 is an explanatory diagram showing a spectral light intensity distribution of diffracted light, and FIG. FIG. 8 is an explanatory diagram showing the signal waveform, and FIG. 8 is a control CGH of FIG.
FIG. 9 is a diagram showing the minimum width in the Y direction of FIG.
FIG. 10 is an explanatory diagram showing the maximum width of H in the Y direction, FIG. 10 is an explanatory diagram showing the minimum width of the control CGH in another example in the Y direction, and FIG.
FIG. 9 is an explanatory diagram showing a maximum width of a control CGH of 0 in the Y direction.

<Shape of Hologram Pattern and Reception Signal Characteristics by Irradiation Optical System> FIG. 1 shows a diffracted light generated by irradiating information CGH with a laser beam (information reflected by the medium is transmitted through the medium). Light may be captured by a two-dimensional CCD. Here, the LD (laser diode) light source 1 is regarded as a point light source, and when the laser light is condensed on the CCD surface 5 by the convex lens 2 (and via the beam splitter 3 and the CGH surface 4), the CCD surface 5 The intensity of the light condensed on it becomes a Fraunhofer diffraction pattern, which becomes a Gaussian distribution. Also,
The light beam immediately after passing through the convex lens 2 is in the same state as when passing through the slit, and has a Fresnel diffraction pattern. The CGH surface 4 is located in the middle between the convex lens 2 and the CCD surface 5 which is a converging point, and the intensity distribution thereof is influenced by each other.

As an example, the distance between the convex lens 2 and the CCD surface 5 is set to 15 mm. In addition, convex lens 2
Neglecting the distance between the beam splitter 3 and the convex lens 2
Is set to 10 mm (that is, the distance between the CGH planes 4 is 5 mm). Convex lens 2
Is 0.3 mm, the beam diameter φ on the CGH surface 4 becomes about 100 μm (= 0.1 mm), and C
The spot diameter φ on the CD surface 5 is 80 μm.

FIG. 2A shows a plan view of one control CGH 13, and FIGS. 2B to 2D show the state of FIG.
For one independent control CGH 13 shown in (a),
The figure shows signals that are irradiated with light S1 to S3 having different spot diameters and received by the light receiving element. The approximate value is shown in FIG.
The control CGH 13 shown in FIG. 2 is a square of 100 μm × 100 μm, and the spot diameter S1 shown in FIGS. 2 (b), (c) and (d).
To S3 are 200 μm, 100 μm, and 50 μm, respectively.

In FIG. 2B, since the spot diameter S1 is sufficiently larger than the control CGH 13, the received light signal has a large tolerance for the movement of the medium. In other words, even if there is a movement error of the medium, the control CGH 13 can be sufficiently read. In FIG. 2D, the control CGH 13 is opposite to that in FIG.
Since the smaller spot diameter S3 is radiated, the received light signal is sensitive to the movement of the medium, and the tolerance is small. Therefore, it is necessary to transport the medium accurately. FIG. 2 (c) is intermediate between FIGS. 2 (b) and 2 (d). Here, in the case of one independent control CGH 13, the control C
It is sufficient to irradiate a spot diameter S1 larger than the GH13. However, when a plurality of control CGHs 13 are closely arranged, irradiating a spot diameter S1 larger than the control CGH13 also irradiates an adjacent control CGH13 to irradiate a plurality of control CGHs.
It becomes an overlapped signal by GH13.

FIG. 3A shows a case where a plurality of control CGHs 13 are arranged in a line in the X direction, and are arranged at equal intervals separated by the length of the control CGHs 13 in the X direction.
FIGS. 3B to 3D respectively show FIGS.
The spot light S having a different size as in the case shown in FIG.
1 shows signals received by the light receiving element by irradiating 1 to S3. In FIG. 3B in which the spot diameter is sufficiently larger than that of the control CGH 13, the received light signal has a waveform with less irregularities (level difference) due to the influence of the adjacent control CGH 13, and the maximum value is as shown in FIG. Same as b), except that the level difference between the maximum values is small (the minimum value is large). In FIG. 3C in which the same spot diameter S2 as the control CGH 13 is applied, the maximum value is the same as in FIG.
At an intermediate position between the two control CGHs 13, the adjacent control C
The influence of GH13 is small and the amplitude is large. In FIG. 3D in which the spot diameter S3 smaller than the control CGH 13 is irradiated, the maximum value is the same as that in FIG. 2C, but at an intermediate position between the two control CGHs 13, the influence of the adjacent control CGH 13 is not affected. There is no length, and the section with the level “0” is long.

FIG. 4A shows two types of different control CGH1s.
3 shows a case where “A” and “B” are arranged alternately and continuously in one row in the X direction. Then, FIG.
(D) respectively irradiates spot lights S1 to S3 having different sizes as in the cases shown in FIGS. 2 (b) to (d),
Odd-numbered and even-numbered control CGH13 "A", "B"
Are received by two light receiving elements, respectively, and a difference signal (AB) between the two light receiving signals A and B is shown.

In FIG. 4B irradiating the spot diameter S1 which is sufficiently larger than the control CGH 13, the level difference between the original signals A and B is small due to the influence of the adjacent control CGH 13, so that the difference signal (AB) ) Is also small. In FIG. 4C in which the same spot diameter S2 as that of the control CGH 13 is irradiated, the amplitude is large because the influence of the adjacent control CGH 13 is small. In FIG. 4D in which the spot diameter S3 smaller than the control CGH 13 is irradiated, the section “0” is long, and FIG.
It does not have a sine curve as shown in FIG.

<Study of Read Timing> FIG. 5A
3A shows a case in which a plurality of control CGHs 13 are arranged in one row in the X direction, and are arranged at equal intervals separated by the length of the CGH in the X direction, similarly to FIG. 3A. . FIGS. 5B to 5D respectively show FIGS.
Light S1 having different spot diameters as in the case shown in FIG.
By irradiating S3, odd-numbered and even-numbered control CGH13
Indicate signals A and B respectively received by the two light receiving elements arranged in the X direction, and sections e, f, and f when the readable range is 80% or more of the maximum value.
g.

In FIG. 5B in which the spot diameter S1 is sufficiently larger than the control CGH 13, the section e is relatively long. In FIG. 5C, the same spot diameter S2 as in the control CGH 13 is irradiated. Then, the section f becomes shorter than the section e. In FIG. 5D in which the spot diameter S3 smaller than the control CGH 13 is irradiated, the section g becomes shorter than the section f.

Here, in order to continuously read the information CGH 12 by the two-dimensional CCD while transporting the medium in the X direction, two types of control C for obtaining the read timing are required.
GH13A and 13B are each arranged in the X direction.
The light is received by the light receiving elements to obtain a difference signal AB between the respective light receiving signals A and B, and this difference signal is binarized at a zero crossing point.
A read timing signal (exposure control signal) may be generated based on the rise and fall of the binarized signal.

(1) In order to detect this read timing signal with high accuracy, the amplitude of the difference signal AB may be increased. For this purpose, the control CGH 13 and the spot diameter S must be the same as shown in FIG. (2) The readable range of the information CGH 12 is widened, and even if the read timing shifts, the information CGH 12
In order to make 12 possible to read, the spot diameter S should be made larger than the control CGH 13 as shown in FIG.

FIG. 6 shows a plurality of light beams (5 in this example) in the Y direction by the beam splitter (BS) 3 of the light of a single LD light source 1.
The optical system shown in FIG. 2 irradiates the information CGH 12 of four rows (2 + 2 pieces outside the center) and the control CGH 13 of one row at the center at the same time. This spectral light intensity distribution is
3 can be freely designed. In this example, the intensity of the central read beam (0th-order diffracted light) is shown as twice that of the information CGH12 read beam (first-order and second-order diffracted lights). . Here, when a single light is split into a plurality of beams by a spectroscope to form a reading beam for information CGH12 and a reading beam for control CGH13,
Although the intensity distribution of each beam can be selected, each beam diameter S
Is the same. However, the read beam diameter S of the information CGH 12 is larger than the information CGH 12 because it is read by a CCD, and the read beam diameter S of the control CGH 13 is preferably the same as the control CGH 13 because it is read by a photodetector.

FIG. 7 specifically shows an optical recording medium according to the present invention. Information CGH12 is 100 μm × 100 μm
The control CGH13 is 200 μm × 200 μm
It is composed of The information CGH12 is 4 in the Y direction.
Control CGH13 arranged in rows (a, i, c, d in the figure)
Are arranged in one row (A and B in the figure) in the Y direction, and the information CGH 12 and the control CGH 13 are 200 μm in both the XY directions.
m. In addition, control CGH for the X direction
Thirteen boundaries coincide with the center of the information CGH12.

Each of the five reading beam diameters S is formed so as to irradiate the entire information CGH 12 by the optical system shown in FIG. In FIG. 1, the diffraction angle of CGH is 1
3.3 mrad, the intensity of the 0th-order diffracted light of the control CGH 13: the intensity of the ± 1st and ± 2nd-order diffracted lights of the information CGH12 =
It is assumed that the intensity of diffracted light of 2: 1, ± 3 or higher order = 0.

While the medium is being conveyed, one central beam is applied to the control CGH 13 and the other four beams are applied to four rows of information CGHs 12, respectively, to provide two types (A and B in the figure). The 0th-order diffracted light of the control CGH 13 is received by two light receiving elements PD (A) and PD (B), respectively, and a difference signal AB between the light receiving signals A and B is obtained. The read timing signal (exposure control signal) is generated based on the rise and fall of the binarized signal. Since the amplitude characteristics of the ± 1st-order and ± 2nd-order diffracted lights of the information CGH 12 become maximum at the center of the information CGH 12, that is, at the boundary of the control CGH 13, the information CGH 12 is two-dimensionally received by a CCD or the like based on the exposure control signal at the maximum. An image can be taken by the element.

<Width of Control CGH in X-direction> As described above, the width of control CGH 13 in the X-direction is determined by the information CGH12.
Even if the diameter of the spot light is larger than the information CGH 12, for example, when the spot light is located at the center of the control CGH 13A, diffracted light is generated from the control CGHs 13B on both sides thereof. Therefore, accurate reading timing in the X direction can be obtained.

<Width of Control CGH in Y Direction> As shown in FIG. 8, the width in the Y direction of the information CGH 12 is set to （(= 100 μm) the width b in the Y direction of the information CGH 12 as shown in FIG. Set to. The minimum width cmin of the control CGH 13 in the Y direction is the width a of the information CGH 12 in the Y direction. That is, 2 × a = b cmin = a. In addition, as shown in FIG.
The maximum width cmax in the direction is cmax = 2 × ba. Therefore, the width c in the Y direction of the control CGH 13 is set to a ≦ c ≦ 2 × ba.

By the way, for the sake of simplicity, only the control CGH 13 for one row has been described so far. However, in order to obtain the reading timing in the X direction absorbing the reading error in the Y direction, FIG. As shown in FIG. 11, four types of control CGHs 13 (A, B, C, and D in FIG.
The data is recorded continuously in the shape of a “field” of columns × 2 rows, and this is repeated in the X direction. In addition, the control CGH 13
Are arranged in the Y direction in such a manner that 2 + 2 rows of information CGHs 12 (a, b, c, d in the figure) are spaced apart from each other, and are recorded while being spaced apart in the X direction. In FIGS. 10 and 11, the boundary between the control CGHs 13A and 13B and the boundary between the control CGHs 13C and 13C in the X direction correspond to the information CGH12.
Match with the center. And four kinds of control CGH1
3A to 13D are received by light receiving elements arranged in a two-dimensional two-dimensional array, and (A + B)-(C + D) is calculated based on each of the light receiving signals A, B, C, and D. Even when the light and the medium are displaced in the Y direction, the reading timing in the X direction can be obtained.

In this case, the width of the control CGH 13 in the X direction is similarly set to the pitch of the information CGH 12 in the X direction (200
μm). And four kinds of control CGH13
A to 13D have the same width in the Y direction, and the Y of the control CGHs (13A, 13C) and (13B, 13D) for two rows.
The minimum width cmin in the direction is the width a in the Y direction of the information CGH12.
And That is, 2 × a = b cmin = a. In addition, as shown in FIG.
The maximum width cmax of H (13A, 13C) and (13B, 13D) in the Y direction is cmax = 2 × ba. Therefore, two rows of control CGHs (13A, 1
The width c in the Y direction of 3C) and (13B, 13D) is a ≦ c ≦ 2 × ba.

According to the present invention, the following inventions are provided in addition to the inventions described in the claims. (1) An information reading apparatus for an optical recording medium for reading a first hologram pattern recorded on an optical recording medium according to any one of claims 1 to 3, wherein the second hologram pattern is generated. Reading means for reading light, means for generating an AC signal that crosses zero at a boundary of the second hologram pattern, based on a signal read by the reading means during conveyance of the optical recording medium; and Means for generating a timing signal for sequentially reading the plurality of first hologram patterns at the centers thereof based on the zero-cross points, the information reader for an optical recording medium.

[0036]

As described above, according to the present invention, the pitch of the first hologram pattern representing information and the length of the second hologram pattern for timing in the transport direction are the same. An accurate timing signal can be generated by reading a hologram pattern for timing generation on an optical recording medium.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of an information recording apparatus for an optical recording medium according to the present invention.

FIG. 2 is an explanatory diagram showing a signal waveform based on a relationship between one control CGH and a spot diameter.

FIG. 3 is an explanatory diagram showing a signal waveform based on a relationship between a control CGH and a spot diameter which are arranged apart from each other.

FIG. 4 is an explanatory diagram showing signal waveforms according to a relationship between a control CGH and a spot diameter, which are arranged alternately in the transport direction so that the boundaries contact each other.

FIG. 5 is an explanatory diagram showing signal waveforms according to a relationship between a control CGH and a spot diameter which are arranged apart from each other.

FIG. 6 is an explanatory diagram showing a spectral light intensity distribution of diffracted light.

FIG. 7 is an explanatory diagram showing an optical recording medium according to the present invention and signal waveforms thereof.

FIG. 8 is an explanatory diagram showing a minimum width of the control CGH in FIG. 7 in the Y direction.

9 is an explanatory diagram showing a maximum width of a control CGH in FIG. 7 in a Y direction.

FIG. 10 is an explanatory diagram showing a minimum width in the Y direction of a control CGH of another example.

11 is an explanatory diagram illustrating a maximum width of the control CGH in FIG. 10 in the Y direction.

FIG. 12 is an explanatory diagram showing a signal waveform by a conventional control CGH.

FIG. 13 is a configuration diagram illustrating an embodiment of an information reading device for an optical recording medium.

FIG. 14 is an explanatory diagram showing another control CGH.

FIG. 15 is an explanatory diagram showing a signal waveform by the control CGH of FIG. 14;

FIG. 16 is an explanatory diagram showing a signal waveform by the control CGH of FIG. 14;

[Explanation of symbols]

12 information CGH (first hologram pattern) 13, 13A, 13B, 13C, 13D control CGH
(Second hologram pattern)

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Man Ueno 3-12-12 Moriya-cho, Kanagawa-ku, Yokohama-shi, Japan 3E044 BA04 BA05 BA06 CA10 DD02 5D029 JB42 JB45 VA08

Claims (3)

[Claims] 1. A plurality of first hologram patterns representing information are arranged at a predetermined pitch in a transport direction,
In an optical recording medium in which a plurality of second hologram patterns for generating a timing signal for sequentially reading the plurality of first hologram patterns during conveyance are arranged in the conveyance direction, the second hologram pattern has a diffraction characteristic. Are arranged such that the hologram patterns are different from each other in the transport direction and the boundaries are in contact with each other, and the first hologram pattern is arranged such that the center in the transport direction coincides with the boundary of the second hologram pattern. An optical recording medium, wherein the length of the second hologram pattern in the transport direction is the same as the pitch of the first hologram pattern. 2. The first hologram pattern, wherein the first hologram pattern is arranged two-dimensionally in a transport direction and a direction orthogonal to the transport direction, and a width in a direction orthogonal to the transport direction of the first hologram pattern is a, and the first hologram pattern is A = c ≦ 2 × ba, wherein b is a pitch in a direction orthogonal to the transport direction of the second hologram pattern, and c is a width in a direction orthogonal to the transport direction of the second hologram pattern. 2. The optical recording medium according to 1. 3. The first hologram pattern is arranged two-dimensionally in a transport direction and a direction orthogonal to the transport direction, and the second hologram patterns are arranged in two rows in a direction orthogonal to the transport direction. A, the width in the direction orthogonal to the transport direction of the first hologram pattern is a, the pitch in the direction orthogonal to the transport direction of the first hologram pattern is b, and the width in the direction orthogonal to the transport direction of the second hologram pattern is 2. 2. The optical recording medium according to claim 1, wherein a ≦ c ≦ 2 × ba, where c is a width of a column.