JP2003122234A - Optical structure for genuineness certification, recording medium for genuineness certification and checking method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance safety to forgery by hiding the presence of even a hologram of a type that the hologram is reconstructed when the hologram is irradiated with coherent light or making this hologram indistinct. SOLUTION: The recording medium 1 for genuineness certification is constituted by having an optical structure 3 arrayed with micro-optical unit areas 4 on a base material 2 and lining up the micro-areas multi-valued with the phase information of a Fourier transform image of an original image and recorded therewith in the form of depth and the micro-areas recorded with diffraction gratings within the micro-optical unit areas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical structure for authenticating authenticity and a recording medium for authenticating authenticity having the optical structure for authenticating authenticity. The present invention also relates to a method for confirming authenticity, which is carried out by using these optical structures or the optical structures of the authenticity recording medium.

[0002]

2. Description of the Related Art A diffraction grating or a hologram is applied to cards such as deposit / saving cards issued by financial institutions or credit cards issued by card companies in order to guarantee their authenticity. Many. In addition, high-priced items such as famous brand watches that imitation products are easy to circulate,
Alternatively, also in such cases, diffraction gratings and holograms are often applied to guarantee their authenticity.

Diffraction gratings and holograms (hereinafter referred to as holograms) are also applied to articles in various fields other than the above examples because holograms and the like have difficulty in manufacturing or copying. In addition, it has an interference color in appearance and is easy to draw attention, and it is also excellent in design, and in some cases, when it is peeled off, it breaks and cannot be diverted to another. This is because it has advantages such as being able to

However, even though holograms and the like are difficult to manufacture and copy, their manufacturing methods are well known to experts, and even if they are forged. Since it is manufactured using a precise processing technique, a product that is very similar in appearance to the real product is obtained, and it is very difficult to distinguish the forged product from it.

Therefore, various attempts have heretofore been made to further enhance the security against forgery of holograms and the like.

In Japanese Patent Laid-Open No. 2000-3124, there is provided a first image and a second image which are configured such that, when irradiated with monochromatic light, the transmitted diffracted light or reflected diffracted light projects a predetermined image indicating that the product is a genuine product. Each hologram pattern is CGH
(Computer Generated Holog
By using an optical recording medium recorded with authentic product display image projection data recorded as ram), it is possible to easily determine whether or not a predetermined image is projected when a predetermined wavelength of monochromatic light is projected. It is disclosed that the authenticity of can be determined. However, in the above-mentioned conventional technique, since the area where the hologram is present is large or the position where it is provided is clear, it is easy to detect the existence of the hologram and its position and analyze the hologram. Therefore, it cannot be said that the security against forgery is sufficient.

[0007]

In the present invention, as in the above-mentioned prior art, although the hologram is of a type in which visually recognizable information is reproduced when irradiated with coherent light, its existence is present. The problem is to increase the security against forgery as a structure for hiding or confusing.

[0008]

In order to solve the above-mentioned problems, the inventor has made both a minute area in which the phase information of the Fourier transform image of the original image is multi-valued and recorded as a depth and a minute area composed of a diffraction grating. By further arranging the aligned units, it was possible to reproduce the hologram with coherent light and to conceal the existence of the hologram.

According to a first aspect of the present invention, micro optical unit areas in which a micro area in which phase information of a Fourier transform image of an original image is multi-valued and recorded as a depth and a micro area in which a diffraction grating is recorded are arranged are arranged. The present invention relates to an optical structure characterized in that A second invention is the optical system according to the first invention, wherein in the first invention, there are a plurality of types of the minute areas in which the phase information of the Fourier transform image of the original image is multivalued and recorded as the depth. It concerns structures. A third invention relates to the optical structure according to the first or second invention, wherein the diffraction grating has a spatial frequency of 10 lines / mm or more. A fourth invention relates to the optical structure according to any one of the first to third inventions, characterized in that the size of the minute optical unit area is 0.3 mm or less. A fifth invention relates to the optical structure according to any one of the first to fourth inventions, characterized in that the shape of the minute optical unit area is a polygon. A sixth invention relates to the optical structure according to any one of the first to fourth inventions, characterized in that the shape of the minute optical unit area is a shape of a character, a number, a figure, or a symbol. A seventh aspect of the invention relates to a recording medium for authenticating proof, characterized in that the substrate has the optical structure according to any one of the first to sixth aspects. An eighth invention irradiates the optical structure of any one of the first to sixth inventions, or irradiates the optical structure of the authenticity recording body of the seventh invention with coherent light, The present invention relates to a method for confirming authenticity, which is characterized by comparing a reproduced image with a reference image prepared in advance to determine whether they are the same.

[0010]

FIG. 1 is a plan view showing an embodiment in which the present invention is applied to cards such as a deposit / saving card or a credit card, which is one of preferred application examples. In FIG. 1, an authenticity proof recording body 1 includes a base material 2
The optical structure 3 for authenticating the authenticity is laminated on the upper surface or the like of the substrate, or embedded so that the upper surface of the base material 2 and the upper surface of the optical structure 3 are flush with each other. To these laminated structures, a transparent protective layer may be further laminated on the upper surface as long as it does not hinder the observation of the optical structure 3 or the reading of information contained therein.

The material of the substrate 2 is polyvinyl chloride,
In addition to resins such as polyester, polycarbonate, polyamide, polyimide, cellulose diacetate, cellulose triacetate, polystyrene, acrylic, polypropylene, and polyethylene, metal such as aluminum and copper, paper, and impregnated paper such as resin or latex alone Alternatively, a sheet or the like made of a composite can be used. When heat resistance is required, a sheet of an amorphous polyester resin, a blend resin of an amorphous polyester resin and a polycarbonate resin, or the like can be used as the material of the base material 2.

Although the thickness of the base material 2 varies depending on the material, it is usually in the range of 10 μm to 5 mm. When the authenticity recording body 1 has the function of a magnetic card, and the base material 2 conforms to the ISO standard, the thickness thereof is 0.76 mm. When the substrate 2 is made of polyvinyl chloride (hereinafter referred to as PVC), the thickness is usually 2
Two 80 μm white PVC sheets are stacked as a core sheet, and 100 μm thick transparent PVC sheets are stacked on both sides as oversheets, and laminated by a heat press or the like to form a four-layer base material (total thickness 0.76 mm ) Is used. In the case of the base material 2 having a four-layer structure, the position where the optical structure 3 is laminated is at the oversheet side of the core sheet,
The core sheet side of the oversheet or the exposed surface of the oversheet is suitable.

When viewed in detail, the optical structure 3 for proof of authenticity is formed by further arranging the micro optical unit areas 4. In the example shown in FIG. 1, a square micro optical unit area is formed. 4 are arranged in a matrix in the vertical and horizontal directions. The size of the optical structure 3 is, for example, several mm to
Although it is about several cm, it may have a size that covers the entire surface of the base material 2.

The small optical unit area 4 constituting the optical structure 3 preferably has a small size for the purpose of making visual confirmation difficult, and specifically, it is preferably 0.3 mm or less. . The size of the micro optical unit area 4 is 0.3 m
This is because when the value exceeds m, the possibility that the minute optical unit area 4 can be visually recognized increases and the possibility that the minute optical unit area 4 is analyzed occurs. The size of the micro-optical unit area 4 is represented by the length of one side in the case of a square, the length of the long side in the case of a rectangle, the diameter in the case of a circle, the long diameter in the case of an ellipse, and other shapes. If there is, the maximum value of the crossover dimension shall be shown. Further, it is preferable that the size of the micro optical unit area 4 is sufficiently smaller than the diameter of the laser beam, because the reason is that when the laser light is irradiated for reproducing the hologram, This is because it is possible to reproduce all holograms and all diffraction gratings. Micro optical unit area 4
The size of can be made small as long as at least two or more minute areas can be formed therein, but it does not hinder mass production and the reproduced image can be easily observed.
It is preferably at least μm.

As shown in FIG. 1, one of the minute optical unit areas 4 is surrounded by a circle and is drawn out downward to be enlarged.
Further, it is composed of subdivided minute areas, and in the example shown in FIG.
6, consisting of micro-areas, each of which is a square. In this example, 36 minute areas are divided into four groups (or groups) each including nine minute areas by dividing the minute optical unit area 4 by vertical and horizontal lines (hypothetical lines) passing through the center of the minute optical unit area 4. It is divided. Of the four groups, each minute area in the upper group on the left side of the four groups is a minute area in which the phase information of the Fourier transform image of the original image A is multivalued and recorded as depth (in the figure, to the lower right). Hatched), and each minute area in the lower group on the right side is a minute area in which the phase information of the Fourier transform image of the original image B is multivalued and recorded as a depth ( In the figure, hatching is shown to the upper right.), And each minute area in the upper group on the right side is a minute area in which the diffraction grating C is recorded (a group of dotted lines in the left-right direction in the figure). , And each micro area in the lower group on the left side toward the left is shown by applying the diffraction grating D-recorded micro area (dotted line groups in the vertical direction in the figure). ) Consists of It is preferable that the micro-optical unit areas 4 are arranged vertically and horizontally in the same direction, as partially illustrated in the drawing.

As described above, the creation of the information recorded as the depth in the minute area of each group based on the original image A and the original image B will be described with reference to FIG. The steps 1) to 7) are sequentially performed for each type of original image. (1) First, an original image is formed. The original image may be an arbitrarily determined image, and may be a character, a number, a figure, or a symbol as well as a painting, an animation, a photograph, or the like. (2) Next, a Fourier transform image of the original image is created by performing a Fourier transform process on the original image using a computer. (3) Amplitude = 1. (4) Inverse Fourier transform is performed. (5) The amplitude is set to the original amplitude (the phase remains unchanged). After that, returning to (2), after repeating "Fourier transform → Fourier inverse transform", the process is stopped when it is determined that a Fourier transform image satisfying a predetermined condition is obtained. (6) After stopping, the phase data is extracted. (7) The phase data is multivalued to obtain depth information of a predetermined number of steps. The obtained depth information should be summarized as "depth information obtained by converting the phase information of the Fourier transform image of the original image into multiple values", but it is often shortened,
This is referred to as "multi-valued depth information based on the original image". Further, among the information recorded as the depth in each of the above groups, the depth information of each diffraction grating or the depth information is multi-valued in the minute area where the diffraction grating C and the diffraction grating D are to be recorded. It may be recorded by using the converted multi-valued information. The depth information of the diffraction grating or the multi-valued information obtained by converting the depth information into multi-values is often shortened to be referred to as "diffraction grating information".

The multivalued phase data based on the original image A and the original image B may be, for example, binarized, 4-valued, 8-valued, or 16-valued. Since the ideal diffraction efficiency is 95.0%, which is sufficient for practical use, binarization, quaternization, or octalization is preferable. The same applies to the case where the phase data based on the diffraction grating C and the diffraction grating D is multivalued.

In the example of FIG. 1, multivalued depth information based on the original image A and the original image B, and information on the diffraction grating C and the diffraction grating D are prepared, and the micro optical unit as shown in FIG. 1 is prepared. Allocate and arrange corresponding to each of the minute areas of the area 4. These operations are also performed on the other micro optical unit areas 4 that make up the optical structure 3. When two or more types of diffraction grating information are divided into sub-micro-optical unit areas, it is preferable to prepare the diffraction gratings having different grating pitches and / or grating directions.

In each micro area within the micro optical unit area,
Allocating the multi-valued depth information as described above
It can be performed by an electron beam drawing device, a grating plotting device, or the like. By exposing and developing the photosensitive resin, fine unevenness on the surface of the cured product of the photosensitive resin or fine unevenness on the etching substrate is formed. It It is of course possible to use these as the optical structure 3 as they are, but normally, as described below, an uneven mold is produced using these as a prototype, and the obtained uneven mold is used to form the optical structure 3. It is preferable to use after mass copying.

In the above example, the minute optical unit area 4 has four areas of minute areas, each of which has two types of multi-valued data based on the original image A and the original image B. The depth information and the information of the diffraction grating C and the diffraction grating D, but the micro optical unit area 4 is at least
It suffices to have two minute areas, each of which is assigned with multivalued depth information based on one kind of original image and one kind of diffraction grating information. The number of types of multi-valued depth information based on these original images and the information of the diffraction grating can be arbitrarily increased. If there are two or more types of multileveled depth information and / or diffraction grating information based on the original image, it is possible to change the coherent light conditions when reproducing the hologram or diffraction grating, for example, changing the irradiation angle. Therefore, the analysis becomes more difficult, and since the authenticity is proved only after confirming all the reproduced images, there is an advantage that the authenticity is assured, that is, the reliability is further enhanced.

Micro-optical unit area 4 which can be of various shapes
3A (the same as FIG. 1), in addition to being densely arranged in a matrix in the vertical and horizontal directions, as shown in FIG. There may be an array in which the second and subsequent rows are deviated by 1/2 pitch, or an array in which they are deviated by 1/3 pitch based on the (alignment).

As shown in FIG. 4, the micro-optical unit area 4 is a polygon such as a triangle (FIG. 4A), a quadrangle, a pentagon, a hexagon (FIG. 4B) ,. It may be a geometrical shape other than a polygon, for example, a circle or an ellipse, a shape such as a character or a number (FIG. 4C), or a shape of an arbitrary figure or symbol (FIG. 4 ( d)). Of these, geometrical shapes such as polygons, circles, ellipses, etc. are preferable in that the processing when allocating multivalued depth information and / or diffraction grating information based on the original image becomes easy. Particularly in the case of a triangle, a quadrangle, or a hexagon, which is a representative of polygons, it is easy to arrange them densely. Also, in the case of shapes such as letters and numbers, arbitrary figures and symbols, even if the shape is known, the interest is in the outer shape itself,
The advantage of camouflaging the existence of underlying information arises. In addition, these shapes can be given meaning, and they can also contribute to a forgery prevention measure.

Depending on the shape of the minute optical unit area 4, FIG.
May be arranged in a manner other than that described with reference to. As shown in FIG. 4A, in the case of a triangle, one side is on the upper side to configure the first row, and when configuring the second row, the adjacent triangles in the first row are The triangles are arranged with one side on the lower side, and the odd rows after the third row are repeated by repeating the first row, and the even rows after the fourth row are 2 rows.
If the lines are arranged by repeating the lines, they can be arranged densely. Alternatively, in the case of hexagons, the hexagons in the first row (vertical row on the left) are closely arranged with the two opposite sides parallel to the left-right direction. By arranging them in a honeycomb shape, such as shifting by 1/2 pitch, it is possible to arrange them densely.

When the minute optical unit area 4 has the shape of the letter "A" shown in FIG. 4C or the shape of the heart shown in FIG. 4D, a gap is formed between adjacent shapes. It is difficult to arrange them without making them, but since the micro-optical unit areas 4 themselves are small, it is difficult to visually recognize the gaps with the naked eye, and it is not always necessary to arrange them closely (= without gaps). However, things that can be arranged closely, such as polygons such as squares,
This is preferable in that the reproducibility of the hologram or diffraction grating can be increased. Therefore, even in the case of shapes other than polygons, it is more preferable that the proportion of the micro-optical unit area in the area of the repeating unit is high.

The shape of the optical structure 3 is not limited to the quadrangle as shown in FIG. 1, and the optical structure 4 itself has the shapes mentioned as the various shapes of the minute optical unit area 4. May be Also, any optical structure 3
There may be a distinction between a portion in which the micro optical unit areas 4 are arranged and a portion in which the micro optical unit areas 4 are not arranged. For example, the micro optical unit areas 4 are arranged within a certain shape in the rectangular optical structure 3. Are arranged, and the minute optical unit areas 4 are not arranged in the other portions, so that the minute optical units 4 are arranged in a character shape.

The optical structure 3 applied on the base material 2 is industrially manufactured by producing a concave-convex mold as described above and mass-reproducing using the obtained concave-convex mold. Preferably there is. As the concavo-convex mold, some of the concavo-convex mold initially obtained by repeatedly performing metal plating on a product manufactured using a photosensitive resin or a product manufactured on an etching substrate is used. It is recommended to manufacture and use a concave-convex mold for reproduction.

For mass replication, preferably, a fluidizing ionizing radiation curable resin (usually an ultraviolet curable resin) is applied on a transparent film, and then a mold surface having a fine concavo-convex shape for replication is contacted. It is preferable to cure the ionizing radiation-curable resin by irradiating it with ionizing radiation (ultraviolet rays if it is an ultraviolet-curable resin) while maintaining contact with the surface. It is possible to obtain a laminate in which a cured resin film of an ionizing radiation curable resin in which irregularities are duplicated is laminated on a transparent film.

The surface of the formed fine irregularities is usually Al.
It is usual to form a reflective layer, which is made of a reflective metal thin film such as the above, or a thin film of a material having a light refractive index different from that of the cured resin film, along the fine irregularities.

A laminated body in which a transparent film, a cured resin film having fine irregularities formed thereon, and a reflective layer are laminated in this order is a transparent film side or a reflective layer side, with a base material via an adhesive such as a heat-sensitive adhesive layer. By stacking with 2, the authenticating recording body 1 having the optical structure 3 on the base material 2 can be obtained.

Alternatively, the transparent film and the cured resin film on which fine irregularities are formed are laminated in a peelable manner, and the reflective layer side is provided with an adhesive such as a heat-sensitive adhesive layer.
A structure having the optical structure 3 on the base material 2 can also be obtained by laminating with the base material 2 and peeling the transparent film at the same time as the laminating, or after the laminating, so-called transfer.

A method of confirming the authenticity will be described by taking the card described with reference to FIG. 1 as an example. As shown in FIG. 5, a laser light source 11 is used for the optical structure 3 of the authenticating recording body 1. Then, the laser light 12, which is coherent light having a predetermined wavelength, is emitted. The beam diameter of the laser light 12 may be smaller than that of the minute optical unit area 4 of the optical structure 3,
It is preferable that the area is larger than the minute area forming the minute optical unit area 4. By this irradiation, the holograms a and b, which are arranged in advance in the minute optical unit area 4 and correspond to the multivalued depth information based on the original images A and B, are reproduced. Since these minute areas in which multi-valued depth information based on the original images A and B are recorded look white under white light, when a large area is provided like a conventional hologram, You can avoid revealing your existence. Further, by the irradiation of the laser beam, the light is diffracted in a specific direction in the minute area where the diffraction gratings C and D are recorded, that is, the information of the diffraction gratings C and D is recorded. These minute areas in which the diffraction grating is recorded appear to be colored in a specific color under white light according to the direction and pitch of the diffraction grating. The reproduced holograms a and b
Are collectively referred to as "reproduced image". The authenticity can be confirmed by comparing the reproduced image with a reference image prepared in advance and determining whether they are the same or different.

Therefore, assuming a certain surface 13, for example, the hologram a in the area 13a on the right side, the hologram b in the area 13b on the left side, the diffracted light c in the area 13c in the back, and Since the diffracted light d can be observed in the area 13d in front, the surface 13 is the upper plate of the box, and the laser light source 11 and the fixing base (not shown) for the authenticity recording body are provided. If a transparent screen is provided in each of the areas 13a to 13d on the upper plate of the box, it is possible to determine the reproduced image using this device. It is possible to easily confirm the authenticity of the authenticity proof recording body 1. Further, the light diffracted in the minute area in which the diffraction grating is recorded may be detected at a predetermined position and used as an auxiliary means for confirming the authenticity.

The present invention basically has the structure described above, but the authenticity proof recording body 1 may include the following elements. The cards described with reference to FIG. 1 usually have a magnetic recording layer in many cases. The magnetic recording layer is usually in the form of a stripe having a width of about 5 to 10 mm, and is provided directly on the surface or inside of the base material 2 by applying a magnetic paint, and is applied to a thin plastic sheet to form a stripe. It is formed by cutting and attaching in a sheet shape, or by transfer using a magnetic recording layer transfer sheet prepared by being removably laminated on a temporary base material sheet.

A general recording medium including a card usually has a magnetic recording layer. The function of the magnetic recording layer may be replaced with an optical recording layer, an IC module or the like. However, even if the optical recording layer and the IC module are provided, it is preferable that the magnetic recording layer having versatility is provided. Further, in addition to the optical structure 3 of the present invention, a normal hologram or the like (including a diffraction grating) may be included. By doing so, attention and attention to the optical structure 3 of the present invention can be provided. You can distract.

The authenticating proof recording body 1 of the present invention may be provided with appropriate characters by printing or the like. In the case of a card, the contents expressed in characters include the issuing company, the name of the card, the issue number, the expiration date, the name of the holder, or a note. Some of these,
For example, issue number, expiration date, and holder's name
It may be formed by embossing unevenness.
In addition, the base material 2 may be colored or patterned to decorate the authenticity proof recording body 1, and is usually printed.

The authenticity recording body 1 of the present invention is not only used for card applications, but various articles are used as the base material 2 and the optical structure 3 is laminated on them. You can Depending on the article, there are cases where the article itself is a recording body having information, and cases where the article itself does not have information but a recording body to which information is added by stacking the optical structures 3.

The authenticity recording body 1 of the present invention may be an ID (identity verification) card, and specifically, a bank savings card, a credit card, an identification card, or the like. Further, it may be an examination voucher, a passport or the like which is not necessarily in the form of a card. The authenticity recording body 1 is
It may be a bill, a gift certificate, a stock certificate, a securities, a passbook, a boarding ticket, an air ticket, or a prepaid card for transportation or a public telephone. These include amount, issuer, issue number,
Alternatively, information such as notes is recorded.

The recording medium 1 for authenticating the authenticity of the present invention does not necessarily have information, but can be various articles provided with information by stacking the optical structures 3. Various articles include, for example, luxury watches, precious metals, jewelry, etc.
It is a so-called brand-name product, which is a world-famous luxury product, and an article such as a storage box and a case thereof, which are usually expensive and thus are likely to be counterfeit. In some cases, a tag that is hung on the product can also be the base material 2 of the authenticity recording body 1.

A storage medium in which music software, video software, computer software, game software, etc. are recorded,
Similarly, for articles such as those cases, as the base material 2,
The optical structure 3 may be laminated. These are not necessarily expensive, but if they are mass copied and sold illegally,
Authorized distributors may suffer serious damage.

In any of the authenticity recording bodies 1, there is a case where a portion other than the optical structure has information,
Optical structure 3 with or without information
With the above, by confirming the authenticity of the optical structure 3, it is possible to confirm the authenticity of the substrate 2 having the optical structure 3, that is, the authenticity recording body.

[0041]

According to the first aspect of the present invention, since the micro area in which the phase information of the Fourier transform image of the original image is multi-valued and recorded as the depth and the micro area composed of the diffraction grating are arranged, According to the above observation, it is possible to provide an optical structure which has a hologram and a diffraction grating which can reproduce only when coherent light is radiated and whose safety cannot be forged because the existence of the hologram is unknown. According to the invention of claim 2, in addition to the effect of the invention of claim 1, since there are a plurality of types of minute areas in which the phase information of the Fourier transform image of the original image is multivalued and recorded as the depth, the hologram is reproduced. It becomes possible to change the irradiation angle of coherent light at the time of analysis, which makes the analysis more difficult and multi-values the phase information of the Fourier transform images of different original images to confirm the authenticity. It is possible to provide an optical structure with higher reliability, in which it is necessary to confirm all reproduced images from a plurality of types of minute areas recorded as depth. According to the invention of claim 3, in addition to the effect of the invention of claim 1 or 2, it is possible to provide an optical structure in which a diffraction grating having a more practical diffraction efficiency is arranged. Claim 4
According to the invention of claim 1, in addition to the effect of any one of claims 1 to 3, since the size of the micro optical unit area constituting the optical structure is defined, the existence of each micro optical unit area is visually confirmed. It is possible to provide an optical structure that is less likely to be analyzed and thus has a reduced probability of being analyzed. According to the invention of claim 5, in addition to the effect of the invention of any one of claims 1 to 4, since the shape of the minute optical unit area is a polygon, the phase information of the Fourier transform image of the original image is multivalued. The process of allocating the converted depth information and diffraction grating information becomes easy, and in the case of a typical polygon such as triangle, quadrangle, or hexagon, it is easy to arrange densely. A structure can be provided. According to the invention of claim 6, in addition to the effect of the invention of any one of claims 1 to 4, since the shape of the micro-optical unit area is a specific shape, it becomes a camouflage of the existence of the inherent information. An optical structure can be provided that has advantages. According to the invention of claim 7, it is possible to provide a recording medium for authenticity proof which can exhibit the effects of the invention of any one of claims 1 to 6. According to the invention of claim 8, it is possible to provide a method of confirming authenticity, which can prove authenticity by an image reproduced using the optical structure.

[Brief description of drawings]

FIG. 1 is a plan view showing an authenticity proof recording body of the present invention.

FIG. 2 is a diagram showing a flow for obtaining multivalued depth information based on an original image.

FIG. 3 is a diagram showing an arrangement of micro optical unit areas in an optical structure.

FIG. 4 is a diagram showing a shape of a micro optical unit area.

FIG. 5 is a diagram illustrating a method of confirming authenticity.

[Explanation of symbols]

1 Recorder for authenticity 2 base materials 3 Optical structure 4 Micro optical unit area

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03H 1/16 G03H 1/16 5B035 1/18 1/18 G06K 19/06 G07D 7/12 19/10 G06K 19/00 D // G07D 7/12 R G07F 7/08 G07F 7/08 AF Term (reference) 2C005 HA02 HB01 HB02 HB04 HB05 HB09 HB10 HB13 HB20 JA02 JA26 JB08 JB09 MA02 MA03 MB01 MB02 MB08 NB01 PA03 QC12 RA03 2 AA50 AA60 2K008 AA13 FF07 FF21 GG05 3E041 AA01 AA03 BA14 BB01 CB02 DB01 3E044 BA04 BA05 CA05 DA01 DA05 DD01 5B035 AA15 BB05 BB11 BB12 BC00

Claims (8)

[Claims] 1. Microscopic optical unit areas in which a microarea in which phase information of a Fourier transform image of an original image is multivalued and recorded as a depth and a microarea in which a diffraction grating is recorded are arranged are arranged. An optical structure characterized by. 2. The optical structure according to claim 1, wherein there are a plurality of types of the minute areas in which the phase information of the Fourier transform image of the original image is multivalued and recorded as the depth. 3. The optical structure according to claim 1, wherein the diffraction grating has a spatial frequency of 10 lines / mm or more. 4. The size of the minute optical unit area is 0.3.
It is mm or less, The optical structure in any one of Claims 1-3. 5. The optical structure according to claim 1, wherein the shape of the minute optical unit area is a polygon. 6. The optical structure according to claim 1, wherein the shape of the minute optical unit area is a shape of a character, a number, a figure, or a symbol. 7. An authenticity proof recording material comprising a substrate having the optical structure according to any one of claims 1 to 6. 8. Coherent light is applied to the optical structure according to claim 1 or to the optical structure included in the authenticity recording body according to claim 7. A method for confirming authenticity, characterized in that the reproduced image is compared with a reference image prepared in advance to determine the difference.