JP5359123B2 - Diffraction grating or hologram - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diffraction grating or a hologram capable of improving such defects that to be "disordered" and to "strongly" diffract light by generating interference of light in accordance with "periodicity" of ruggedness are contradictory to each other when enhancing a forgery prevention effect according to disorderliness of hidden information and that a large fluctuation/irregularity is caused in brightness or tone of color of the diffraction image or hologram image when visually observing the whole of diffraction grating or hologram prepared by the technology, in regard to the diffraction grating or hologram having the hidden information according to a rugged structure incorporated as information difficult to ascertain by visible sight in various kinds of picture patterns used for security application. <P>SOLUTION: Diffraction grating lines each of which is formed by arranging prescribed information as the hidden information into a column of rugged shape are arrayed regularly in parallel with a period of length double the visible light wavelength and, thereby, the interference of the diffractive light of the diffractive grating or hologram is intensified to provide a diffractive image without fluctuation or irregularity. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a concavo-convex structure mainly used for security applications, and more particularly, to a concavo-convex structure incorporated as information that is difficult to confirm visually in various patterns used for security applications such as diffraction gratings and holograms. The present invention relates to a diffraction grating or hologram having hidden information.

  (Main application) The main application of the diffraction grating or hologram of the present invention is a diffraction grating or hologram used in the field of anti-counterfeiting. Can cause damage to cardholders and card companies, driver's licenses, employee ID cards, ID cards such as membership cards, entrance examinations for entrance examinations, passports, banknotes, gift certificates, point cards, stock certificates, There are securities, lottery tickets, horse betting tickets, bankbooks, boarding tickets, pass tickets, air tickets, admission tickets for various events, play tickets, prepaid cards for transportation and public telephones.

  Each of these is an information recording body that holds information having economic or social value, and it is desirable to have a function that can identify the authenticity of the recording body for the purpose of preventing damage caused by forgery. .

  In addition to these information recording media, expensive products such as luxury watches, luxury leather products, precious metal products, jewelry, etc., often referred to as luxury brand products, or storage of such expensive products. Boxes and cases can also be forged. In addition, mass-produced products of famous brands, such as audio products, electrical appliances, etc., or tags that are hung on them are also subject to forgery.

  Furthermore, a storage body in which music software, video software, computer software, game software, or the like, which is a copyrighted work, or cases thereof can also be forged. In addition, it is desirable that products such as printer toner, paper, and the like in which supplies to be replaced are limited to genuine materials have a function of identifying their authenticity for the purpose of preventing damage caused by forgery.

  In particular, the diffraction gratings or holograms of the present invention must be identified in fields where it is physically and economically impossible to produce the same, that is, arts and antiques. It is most suitable for the field where the value cannot be proved, or the field where it is necessary to confirm by the method that only the owner or the person concerned can know that it is very precious and not imitation.

Focusing on expensive cash vouchers, forgery cases with color copiers have frequently occurred in recent years.
For this reason, money vouchers such as high-value banknotes and gift certificates incorporate a small halftone dot or fine line that cannot be read by a color copier sensor in a part of the design, in a pattern designed with the same reflection density. . As a result, when trying to copy these high-value banknotes and gift certificates with a color copier, the copier scanner reads out small dots and fine lines, and those parts are identified as white and are identified as copies. .

(Background technology)
In addition, holograms that require advanced duplication techniques have been adopted for some high-value banknotes and other cash vouchers.
Holograms are also used as copy restraining means because a metal reflection layer is formed on the uneven surface to reproduce the hologram forming portion in black when the hologram is copied.
However, due to technological progress, counterfeit products similar to holograms have appeared. In order to check such a counterfeit product, a technique is disclosed in which hidden information that is difficult to discriminate is incorporated into a light diffraction structure of a hologram, that is, a diffraction grating, and used as a means for discriminating authenticity.
However, products using these technologies also have a problem that hidden information is slightly discriminated depending on the viewing angle.

  In order to solve such a problem, an authenticity identification structure constituted by a diffraction grating including hidden information that is extremely difficult to discriminate by a visual means and a manufacturing method thereof are provided (for example, see Patent Document 1). The technique disclosed in Patent Document 1 has first hidden information in a design constituted by a diffraction grating, and the first hidden information further includes characters / symbols or a combination thereof. The hidden information is formed by unevenness. The size of the second hidden information is 0.5 μm to 50 μm and is difficult to read even with a simple microscope.

  Moreover, even if the information on the unevenness formed as the second hidden information is read with a precise microscope, the information is random (random) information and the size is also formed randomly. When trying to counterfeit, since it is impossible to make an authentic one unless the information and size of all parts of the diffraction grating design are completely read and reproduced, it has a high anti-counterfeiting effect.

JP 2007-292899 A

  The technique disclosed in Patent Document 1 has improved anti-counterfeiting effect due to its disorder, but it is “disorder” and generates interference of transmitted light or reflected light due to “periodicity” of unevenness. This is contrary to the “principle principle / principle” of diffracting light “strongly”. When the entire diffraction grating or hologram produced by this technique is observed visually, the brightness of the diffraction image or hologram image There were large variations and unevenness in the shade. Moreover, the degree of variation and unevenness cannot be predicted at the design stage, and the procedure of actually creating a diffraction grating or hologram and observing the finish (brightness and color tone of the image) and partially correcting it is not taken. There was a drawback of not obtaining.

Grating or hologram beam of the present invention, the diffraction grating having a relief shape of the period of twice the length of the visible light wavelength or, a hologram, and in that the diffraction grating, whose grating lines, predetermined The section of the diffraction grating lines in the vertical direction is periodic, and is composed of a row of uneven structures for displaying any of the characters, symbols, designs, or any combination information (hereinafter referred to as predetermined information). thereby constituting a diffraction grating line group relief profile having the shape of the cross section that have a periodicity.

As a basic structure, a plurality of “diffraction grating lines” are arranged in parallel (hereinafter also referred to as “diffraction grating line group”). The relief shape of the diffraction grating line group can be observed.
This relief shape has “perfect periodicity” (the curve is formed by repeating one cycle of the same shape in exactly the same shape).

That is, the cross section in the direction perpendicular to one “diffraction grating line” in the diffraction grating line group is configured by, for example, one convex portion of the grating line, and the groove portion between the subsequent grating lines is formed. , It becomes a shape constituted by one concave (this one unevenness is one cycle). This means that the uneven shape (for one period) is the same as the vertical cross section of the other “diffraction grating lines” arranged side by side.

  For example, it has the same periodicity as a trigonometric function. Every function with periodicity (any irregular shape) is always represented by “sum of normal trigonometric functions”. In this case, one period of “sum of normal trigonometric functions” is one “diffraction grating line”. This is contrasted with a set of concavo-convex shapes formed by a cross section and a cross section of a single groove between the diffraction grating lines.

  When this diffraction grating line group is illuminated with a certain light source (also referred to as light to be observed), this diffraction is based on the relationship between the wavelength of the light from the light source, the uneven shape, the period size, and the number of uneven portions. Diffraction light of a grating line group (light diffracted by this diffraction grating line group when transmitted or reflected through the diffraction grating line group. Also referred to as a reproduction image or a diffraction image. In the case of a group of diffraction grating line groups in which the angles arranged in parallel are varied), the reproduction images of the individual diffraction grating line groups are combined to form a more complex reproduction image and further a hologram image. And the diffraction angle (diffraction direction) and the like are determined.

When the light to be observed is visible light as in the present invention, the wavelength is approximately 400 nm to 800 nm, and thus the above-described period is twice, that is, 0.8 μm to 1.6 μm.
Which numerical value is adopted in this range is determined by the wavelength or wavelength range of the actually used observation light and the reproduction image reproduced by the diffracted light, that is, the design of the diffraction image or hologram image.

Regarding the concavo-convex shape of the cross section of a pair of “diffraction grating lines” and “grooves between diffraction grating lines” (hereinafter also referred to as “one diffraction grating line”), When viewed in the direction along, the shape of the unevenness will change variously depending on the shape of the predetermined information, but the uneven shape of the cross section of a pair of “diffraction grating lines” and “grooves between diffraction grating lines” The adjacent concavo-convex shape of the same cross-section (within one diffraction grating line group) changes its shape in synchronism. The change of the shape is synchronized from end to end of the “diffraction grating line”.
That is, when a plurality of “diffraction grating lines” of the present invention are looked down, it can be seen that a number of complicated uneven structures along one diffraction grating line are arranged in parallel with each other in exactly the same shape.

In the present invention, as a simple specific example, along one “diffraction grating line”, predetermined information as hidden information (for example, a letter “H”) is “letterplate of letter“ H ”in letterpress printing”. as in, it is formed in a concavo-convex structure. This is formed as “HHHHHHH...” Along the “diffraction grating line”. A plurality of diffraction grating line groups formed in parallel with the “diffraction grating lines” have the same three-dimensional shape as the “diffraction grating lines” from end to end, and are viewed in the vertical direction described above. And all the characters on the “diffraction grating line” are arranged at the same position.

  With this arrangement, the cross-sectional shape in the vertical direction has an accurate periodicity like a trigonometric function. Since the period of this cross-sectional shape is a factor that determines the diffraction direction and color tone of light, it is possible to design a complex reproduced image such as a color hologram image by having periodicity in the direction perpendicular to the “diffraction grating line”. This is desirable. However, the effect of the present invention can be obtained even if the periodicity is provided in a predetermined direction (a direction shifted by a predetermined angle from the vertical direction), even if not in the vertical direction.

  However, when the predetermined information is a single “H” character as shown in the above example, since the same character is arranged in a direction parallel to the “diffraction grating line”, the “period” is also in the direction parallel to the “diffraction grating line”. ”Occurs, producing strong diffracted light in this direction. In this case, diffracted light in a direction perpendicular to the “diffraction grating line” and diffracted light in a direction parallel to the “diffraction grating line” are generated strongly, and second-order diffracted light is also generated diagonally. Therefore, the intensity of the diffracted light in the vertical direction (contributing to the formation of the reproduced image), which is the object of the present invention, is reduced.

  The number of “diffraction grating lines” in the vertical direction is that the period is twice the visible light wavelength (the visible light wavelength region is 400 nm to 800 nm, so the period is the light to be observed within that range. It is desirable that 10 or more exist, and in order to suppress diffraction in a direction parallel to the diffraction grating line, the same character string is not used, but “HOL. Thus, it is preferable to repeat the characters of at least 3 characters (3 times or more of visible light wavelength), desirably 5 characters or more (5 times or more of visible light wavelength).

When the above conditions are met, when the diffraction grating of the present invention is illuminated as light for observing white visible light, diffracted light having a desired intensity and color tone in a predetermined direction can be observed.
Of course, the predetermined information is not limited to the above example, and can be any of characters, symbols, designs, or a combination thereof, and color holograms can be obtained by combining diffraction grating groups having different periods and angles. It is also suitable to reproduce.

By using the diffraction grating of the present invention, it is possible to stably obtain diffracted light having the diffraction angle, intensity, and color tone as designed above, and it is easy to obtain a desired hologram image.
The shape of the unevenness is a predetermined shape such as a convex portion representing a predetermined information and a flat concave portion, a convex portion representing the predetermined information and a concave portion which is point-symmetric, or the reverse combination, or a staircase structure having three or more layers. Any structure that can read information can be adopted.

  However, as the uneven shape becomes more complicated, the distribution of diffracted light due to repetition becomes more complicated, and it becomes difficult to assume (design) the intensity and color tone of the diffracted light. A desired reproduced image can be designed by using the technique. Further, a structure capable of reproducing the intensity distribution and the color tone distribution of the diffraction grating or hologram to be reproduced may be designed after actually measuring the diffracted light and setting the intensity distribution and the color tone distribution as initial conditions.

  The concavo-convex shape represents predetermined information with a size of about visible light wavelength, that is, a size of 0.4 μm to 0.8 μm, but the concavo-convex shape can be further complicated, and the size is 0.01 μm or less. Because it is possible to incorporate the shallow and fine unevenness change formed in step 1 and the curve that changes from the concave portion to the convex portion as the predetermined information, these complex changes can also be used as an element of authenticity judgment and “forge” This can be made even more difficult. The height of the concavo-convex shape, that is, the maximum value of the relief shape depth is determined by the design of the diffracted light intensity, the above-described forming method, and the refractive index of the forming material, but is 0.8 μm or less, preferably 0 20 μm to 0.50 μm is preferable.

  Various methods are used to form the uneven portion. In particular, by using electron beam lithography or X-ray lithography, it has high resolution and the stability of the concavo-convex shape of the entire formation surface (the predetermined concavo-convex shape is the same shape over the entire surface of the diffraction grating or hologram). Contributes to realizing reproducibility of uneven shape, that is, periodicity without distortion and image reproducibility without distortion.), Parallelism of diffraction grating lines (within 0.01 μm at 10 mm), spacing A relief excellent in accuracy (within 10 mm, the deviation of each line is within 0.05 μm) can be obtained.

In addition, these lithography techniques have a characteristic that the positional accuracy of the predetermined information of the diffraction grating lines is very high. When the cross-sectional shape in the direction perpendicular to the diffraction grating is viewed, the same position of the same information on each diffraction grating line ( For example, it becomes a cut surface at the left end portion of “H”, and a high periodicity effect can be produced. That is, it is possible to obtain a relief structure free from variations and unevenness as designed, and to obtain a diffraction grating or hologram having reproducibility as designed.
For electron beam resist compounds, polymethyl methacrylate, polyolefin sulfone, etc. are used as positive types, and unsaturated polymers, epoxy resins, silicone resins, etc. are used as negative type electron beam resists. High resolution. Further, the electron beam drawing apparatus preferably has a high acceleration voltage (50 kV or more), and more preferably an apparatus capable of narrowing the electron beam system to the nm order.
As the X-ray resist compound, polymethyl methacrylate or the like is used.

  In order to increase the diffraction intensity, it is more desirable to consider that the uneven shape does not change so much in the direction along the diffraction grating line. As described above, it is a feature of the present invention to satisfy both the difficulty of interpreting predetermined information and the conflicting intensities of diffraction. Using this relief master, various manufacturing methods for relief diffraction gratings or holograms enable the production of diffraction gratings or hologram sheets, labels, and transfer foils that are highly anti-counterfeiting and excellent in design. Manufacture and form on various media that should be given security, and verify the authenticity of the various media.

Grating or hologram beam of the present invention is pre-Symbol predetermined information is "white display", the image area of that, is the same area of the non-image area, and the area of the non-image portion Is the sum of the non-image area of the predetermined information display area and the area between the “diffraction gratings”.
The area of the non-image area is the sum of the non-image area of the predetermined information display area and the area between the “diffraction grating line” and the “diffraction grating line” (for example, the total area of the recesses). Otherwise, the area of the image line portion (for example, the total area of the convex portions). This area ratio is set to 1: 1, and the area of the concave portion, that is, the rectangular bottom surface, and the convex portion, that is, the rectangular top surface are made the same.

Thereby, since the amount of light of the bottom surface reflected light and the top surface reflected light of the rectangular diffraction grating can be made the same for each predetermined information, the unevenness without the predetermined information is a diffraction close to a one-to-one rectangular diffraction grating. Efficiency can be obtained. In addition, since the area of the image line portion can be secured large, the legibility of the predetermined information can be improved.

A second aspect of the diffraction grating or hologram of the present invention, prior Symbol predetermined information more than five times the wavelength of visible light, and is characterized in that it is repeated length information within 20 times.
The diffraction efficiency of a rectangular diffraction grating is a standard rectangular (one-dimensional) diffraction in which the cross section in the direction perpendicular to the “diffraction grating line” has an irregularity ratio of 1: 1 when the diffraction grating line does not have predetermined information. It is the highest when it is a grating (it looks like a one-dimensional grating when viewed from the front), and the ratio of the unevenness of the cross section in both directions perpendicular to the “diffraction grating line” and parallel to the “diffraction grating line” is one pair. It is lowest when it is one standard rectangular (two-dimensional) diffraction grating (it looks like a two-dimensional grating when viewed from the front).
Further, when the shape of the cross section is viewed, it is preferable that the cross sectional shape of the convex portion and the cross sectional shape of the concave portion are formed symmetrically with respect to the switching point between the convex portion and the concave portion so that the diffraction efficiency becomes high. .

However, in the diffraction grating line group positioned in the one-dimensional diffraction grating, when the cross section in the “diffraction grating line” direction is random unevenness having no periodicity from end to end (period in the vertical cross section). Since the amplification effect due to interference of diffracted light cannot be expected in the direction of the diffraction grating, the periodicity within at least 20 times the visible light wavelength, preferably within 10 times the visible light wavelength. Is desirable. However, in the case of 1 time, since it becomes the above-described two-dimensional grating and the diffraction efficiency is lowered, it is preferable that it is 3 times or more of the visible light wavelength, preferably 5 times or more.
Accordingly, the repetition length of the predetermined information is preferably within 20 times the visible light wavelength, preferably 5 times or more and within 10 times.

Furthermore, according to the diffraction grating or hologram beam of the present invention, the single grating lines comprising the predetermined information is a hidden information as unevenness of a line, regularly parallel with a period twice as long as the wavelength of visible light By arranging the diffraction grating or the diffraction grating or hologram, the interference of “transmitted light” or “reflected light” (also referred to as “diffracted light”) of the diffraction grating or hologram can be improved, and a diffraction image free from variation and unevenness can be obtained. There is an effect that can be done. Furthermore, it is possible to achieve both readability of predetermined information and diffraction intensity.

In addition, since the diffracted light intensity distribution is stable, it is possible to obtain a reproduced image as expected in the design stage, and there is an effect that the trouble of partially correcting the finish while observing is unnecessary.
Further , by making the concavo-convex structure into a rectangular waveform, there is an effect that the intensity of diffracted light is increased and reproduction image prediction at the design stage is facilitated.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
With reference to FIG. 1, an example of a diffraction grating representing predetermined information of the present invention will be described.
The diffraction grating lines in FIG. 1 represent a predetermined information consisting of a single line of concave / convex structure that displays any one of predetermined characters, symbols, designs, or combination information thereof (hereinafter referred to as predetermined information). Become. The predetermined information may be any character, symbol, or design, or combination information thereof. As the concavo-convex structure forming method, any of fine processing methods capable of submicron processing (pattern processing of 1 μm or less) can be adopted.

  In the example of FIG. 1 (diffraction grating A), the letters “AＡC ··” are set as the predetermined information, and the convex portion and the concave portion are line-symmetric. The height / width of the character is 0.5 μm × 0.5 μm (becomes a diffraction grating with a period of 1.0 μm), which can be formed by electron beam lithography. By setting the thickness of the electron beam resist to 0.6 μm, distributing the electron beam intensity symmetrically, and suppressing the development processing time, it is possible to form a relief master in which irregularities continuously change.

Looking at the aa cross section of this relief master, it is a gentle curve with periodicity as shown in FIG. 2, and the curve within one period has point symmetry with its center point as the symmetry point. ing.
FIG. 3 is a view of the diffraction grating A as viewed from above.
Similarly, in the same predetermined information array, the character height / width is 0.625 μm × 0.5 μm (becomes a diffraction grating with a period of 1.25 μm) and 0.75 μm × 0.5 μm (period 1). A diffraction grating line group (which becomes a .5 μm diffraction grating) is formed, and each is arranged in three areas (B1, B2, B3) in FIG.

  By adjusting the relief period and relief depth (height in FIG. 2) of these diffraction grating lines, the color tone and brightness (light intensity) when observed can be controlled, and each diffraction By devising the arrangement method of the grating line group (the shape occupied by the diffraction grating line group, the area, the method of interspersing, etc.), it is possible to form a diffraction grating with a complicated design or a color hologram. That is, a diffraction grating line group having the same pitch and the same angle is filled in a predetermined area to form a diffraction grating line group for each area, and each area has a predetermined area, a predetermined pitch, and an angle. If all the areas are allocated and observed with white light, a color hologram image can be seen.

Next, a method for creating a sheet-like diffraction grating or hologram using the above-described diffraction grating master will be described.
As a transparent base material, it is possible to reduce the thickness, and have mechanical strength and solvent resistance and heat resistance that can withstand the processing when manufacturing diffraction gratings or hologram sheets, labels, and transfer sheets. use. Since it depends on the purpose of use, it is not limited, but a film-like or sheet-like plastic is preferable.

For example, various plastic films such as polyethylene terephthalate (PET), polycarbonate, polyvinyl alcohol, polysulfone, polyethylene, polypropylene, polystyrene, polyarylate, triacetyl cellulose (TAC), diacetyl cellulose, and polyethylene / vinyl alcohol can be exemplified. .
From the same consideration, the thickness of the transparent substrate is desirably 5 to 50 μm, particularly 5 to 15 μm. When forming the transfer sheet, the transparent substrate 1 may be provided with a release layer made of a commonly used cellulose acetate resin, methacrylic resin or the like.

  Various thermoplastic resins, thermosetting resins, or ionizing radiation curable resins can be used as a transparent resin material for constituting a diffraction grating or a layer for forming a hologram (hereinafter referred to as a hologram forming layer). . Thermoplastic resins include acrylic ester resins, acrylamide resins, nitrocellulose resins, or polystyrene resins. Thermosetting resins include unsaturated polyester resins, acrylic urethane resins, epoxy-modified acrylic resins, and epoxy-modified unsaturated resins. A polyester resin, an alkyd resin, a phenol resin, etc. are mentioned.

  These thermoplastic resins and thermosetting resins can be used alone or in combination of two or more. One or more of these resins may be cross-linked using various isocyanate resins, or various curing catalysts, for example, metal soap such as cobalt naphthenate or zinc naphthenate may be blended. Or peroxide such as benzoyl peroxide and methyl ethyl ketone peroxide for initiating polymerization with heat or ultraviolet light, benzophenone, acetophenone, anthraquinone, naphthoquinone, azobisisobutyronitrile, or diphenyl sulfide good.

  Examples of the ionizing radiation curable resin include epoxy acrylate, urethane acrylate, acrylic-modified polyester, etc., for the purpose of introducing a crosslinked structure into such an ionizing radiation curable resin or adjusting the viscosity, A monofunctional monomer, a polyfunctional monomer, or an oligomer may be blended and used. In order to accurately reproduce fine irregularities, it is preferable that the viscosity is 0.001 to 0.1 Pascal second. This precision is important in authenticity determination, and an ionizing radiation curing method that can faithfully reproduce the shape of the master without any defects and that can reduce shrinkage and expansion after replication is desirable.

When a thermosetting resin or ionizing radiation curable resin is used, curing is performed by heating or irradiation with ionizing radiation while keeping an uncured resin in close contact with the mold surface. It is possible to form fine irregularities of a relief hologram that is less deformed by thermal changes. According to this method, a minute unevenness change of about 0.01 μm can be accurately replicated.
Furthermore, as a method for accurately reproducing a fine shape, it is also preferable to perform replication at low temperature and high pressure in order to minimize distortion and deformation such as heat shrinkage after replication.
In this case, it is preferable that the duplication method is a flat plate type or a rotary type, the linear pressure is 0.1 ton / m to 10 ton / m, and the duplication temperature is usually 60 ° C. to 200 ° C.

Further, a reflective thin film layer is formed on part or all of the hologram relief surface of the hologram forming layer. Since this thin film needs to reflect incident light, it is not particularly limited as long as it is a thin film having a higher refractive index than the hologram forming layer.
The reflective thin film may be either a metallic gloss reflective layer such as a metal thin film formed by a vacuum thin film method or a transparent reflective layer, but a metallic gloss reflective layer is provided partially or a transparent reflective layer is provided. In this case, it is preferable because the security object provided in contact with the reflective layer can be confirmed through the transparent reflective layer.

As a transparent reflective layer, it is almost colorless and transparent, and its optical refractive index is different from that of the hologram forming layer. A simple hologram can be produced. For example, a thin film having a higher refractive index than that of the hologram forming layer, for example, ZnS, TiO ₂ , Al ₂ O ₃ , Sb ₂ S ₃ , SiO, SnO ₂ , ITO, etc.

Preferably, it is a metal oxide or nitride, specifically, Be, Mg, Ca, Cr, Mn, Cu, Ag, Al, Sn, In, Te, Ti, Fe, Co, Zn, Ge, Pb. Cd, Bi, Se, Ga, Rb, Sb, Pb, Ni, Sr, Ba, La, Ce, Au, and other oxides or nitrides, and the like can be exemplified by a mixture of two or more thereof. Also, a general light-reflective metal thin film such as aluminum can be used as a transparent reflective layer when it has a thickness of 20 nm or less and becomes transparent.

  As with the metal thin film, the transparent metal compound is formed by vapor deposition, sputtering, ion plating, CVD (chemical) on the hologram relief surface of the hologram forming layer so as to have a thickness of about 10 to 2000 nm, preferably 20 to 1000 nm. It may be provided by a vacuum thin film method such as a vapor deposition method. In order to faithfully cover fine irregularities, CVD is particularly suitable. However, in order to obtain the same reproduced image not only with the reflected light from the surface in contact with the relief hologram but also with the reflected light on the opposite surface, it is necessary to make the unevenness of the thin film the same shape as the relief hologram, The thickness of the thin film is about 10 nm.

When the diffraction grating or hologram is used in a transfer form, a heat-sensitive adhesive layer is formed on the reflective layer to form a transfer film, and the adhesive layer is included depending on the heated metal mold or the like. A very thin resin layer is transferred onto the security object.
When a diffraction grating or hologram is used in the form of a label, an adhesive layer is formed on the reflective layer, the adhesive surface is covered with release paper, and the base film is sized together with the release paper. Used as a label by punching it out, peeling off the release paper and sticking it on the security object.

  Of course, if the diffraction grating or hologram of the present invention is not only the design property and anti-counterfeiting property, but is the only means for authenticating the security object, it can be easily peeled off from the security object. When the security object is molded, the diffraction grating or hologram of the present invention is embedded as an integral molding, or when the diffraction grating or hologram of the present invention is to be peeled off, the security object or diffraction of the present invention It is also desirable to further improve the anti-counterfeiting as an integral part of the security object, such as the grating or the hologram itself being destroyed.

For example, the hologram sheet can be disposed between two 1 mm plate glasses via a 50 μm glass adhesive sheet and bonded and fixed at 100 ° C. and a pressure of 3 kg / cm 2. Also, when acrylic resin is molded in two colors at 120 ° C. (a method in which two types of resins are molded at the same time to produce a molded product consisting of two layers), a hologram sheet is inserted between them, and the interior of the molded resin product It is also preferable to embed in. Further, it is also preferable to sandwich the certificate card under a vinyl chloride 100 μm oversheet and to keep it in the card by ordinary card processing.
Since these materials are transparent, predetermined information can be read optically from the outside.

  Furthermore, the diffraction grating or hologram of the present invention is a "reconstructed image" (a single image formed as a collection of a number of diffraction images) that is a diffraction image of a diffraction grating line group that is a set of "diffraction grating lines". ) Or “color hologram image” (a diffraction hologram line group is appropriately distributed for reproduction of diffraction images of three colors of R (red), G (green), and B (blue), and is observed with white light. The pitch of the “diffraction grating line” is twice as long as the visible light wavelength (400 nm to 800 nm) in order to ensure the reproduction efficiency (one of the indices indicating the diffraction intensity). (0.8 μm to 1.6 μm) and irregular shape of predetermined information (a series of individual information of height 0.4 μm to 0.8 μm, width 0.4 μm to 0.8 μm) on one diffraction grating line And other "diffraction grating lines Identical irregularities of, and, when viewed in a direction perpendicular to the grating lines, and configured to be positioned exactly in the same position, to enhance the interference effect of light, to enhance the diffracted light intensity.

The higher the position accuracy is (within ± 10% of the predetermined information width, preferably within ± 1%), the higher the diffracted light intensity can be.
However, strong diffraction intensity can be obtained even if the identity in the vertical direction is not the vertical direction but also the 80 degree direction and the 70 degree direction (while maintaining the positional accuracy), but the vertical direction has the highest diffraction efficiency. Highly desirable.
The depth of the unevenness may be a gentle curve or a stepped shape from 0 to the visible light wavelength (0.8 μm), but it is desirable that the unevenness shape assumed for each predetermined information has a high diffraction intensity. It is more desirable that the diffraction intensity assumed for the concave / convex shape of the predetermined information and the diffraction intensity as a diffraction grating line group be high.

  Therefore, when the cross-sectional shape in the perpendicular direction of the “diffraction grating line” in which the convex portion and the concave portion repeat at a visible light wavelength period as in the example of FIG. 1 is seen, the convex sectional shape and the concave portion It is preferable that the cross-sectional shape is formed symmetrically with respect to the switching point between the convex portion and the concave portion because the diffraction efficiency is high. In addition, for ease of formation of the diffraction grating, for example, the convex portion may include predetermined information and the concave portion may be flat, and further, the concave portion may be flat and the convex portion may be stepped to ensure diffraction intensity. In addition, design calculation of diffraction efficiency can be facilitated.

  The predetermined information may be arbitrary, may be random (such as a random number generated by a random number generator), or may be the same letter / symbol / design repeated (in this case, the diffraction efficiency can be easily calculated). Because it is information that is incorporated as information that is difficult to confirm visually, information related to various patterns as the color hologram image adopted for security applications, and security objects to which this color hologram image is transferred or pasted It is also possible to include information that can prove the authenticity of the diffraction grating or hologram of the present invention, such as information related to the above, or related products, names of companies that provide the products, and marks.

In the above example, the predetermined information width is 0.5 μm, but this width is not limited and can be arbitrarily set. For example, it may be a single character / symbol / pattern from the end of the “diffraction grating line” to the bridge. For example, from the end of the color hologram image to the end, the “diffraction grating line” is interrupted as information. It may be connected.
Since this predetermined information cannot be discriminated by visual observation or a simple microscope, in order to confirm the authenticity, the information is read using a high-precision microscope, and “regular information” (the predetermined information is actually converted into a physical shape). Information for determining authenticity at the time of formation, which may include not only the predetermined information itself but also information such as the shape, etc. In addition to the predetermined information, the data obtained by measuring the shape, etc. It may be necessary to determine whether or not the information transformed into the above may be used.

  The judge needs to have accurate knowledge about the “regular information” when making the judgment. However, as described above, if the information is about various designs or security objects as a color hologram image, a special inquiry will be made. It is possible to easily presume that the information is authentic by preliminarily sending a message of “related information is included as a hidden character” to the judge. Alternatively, it is also possible to use a method in which only a part of the hidden character feature is sent and placed.

Of course, when “authenticating authenticity” (when determining whether a counterfeit product is authentic, for example, when making a highly reliable determination, such as when using some evidence), as “regular information”, for example, text In addition to information on symbols and symbols, it is necessary to set more information such as the size, the thickness of the image area, the height of the unevenness, and check all of them.
As a method of leaving the “regular information” of the predetermined information in the data, the three-dimensional shape information obtained by a high-resolution laser microscope is acquired, and this data and the “confirm authenticity” measured for the appraisal It is also preferable to use a method of collating data and determining “authentic” with “a certain degree of coincidence” such as “50% or more coincidence” or “100% coincidence” depending on the collation item.

  Since these pieces of legitimate information are key information for authenticating the authenticity, it is desirable to store and store them physically or electronically in a place with high security level (physical or electronic). Of course, encryption by DES (Data Encryption Standard), AES (Advanced Encryption Standard, same as the left) or the like may be performed. In that case, it is also preferable to provide key information to a plurality of appraisers while maintaining the confidentiality by using various key management methods such as a common key method and a public key method with higher confidentiality.

  In a simple example, it may be written on a predetermined sheet and stored in a safe or the like, or recorded as electronic data in a predetermined holder of a server that is restricted in access (password setting, etc.) The system may require a password input when reading the holder so that only a limited person can read it. In any case, it is required to define a management method in consideration of the level of confidentiality of legitimate information and considering availability (ease of use).

  It is also preferable to change the predetermined information in the middle of the “diffraction grating line” or to change the pitch information when the pitch (period) or angle of the diffraction grating line group is changed. Furthermore, “diffraction grating lines” in an area where the pitch and angle of the diffraction grating line group are the same are “continuous” (assuming that there is no blank, regardless of the blank between the areas) A predetermined information) may be formed.

By doing so, a person who intends to counterfeit exactly the same thing forges the “same thing” unless he / she decodes all the predetermined information of all “diffraction grating lines” of the diffraction grating or hologram of the present invention. The situation can not be.
Of course, the predetermined information may be changed for each diffraction grating line group, but in this case, it is necessary to arrange the diffraction efficiency for each predetermined information.
Predetermined information and information on the uneven shape can be held as authenticity proof information by information as an actual pattern, uneven design information, and each lithography formation information (in electron beam lithography, an electron beam drawing program or the like). Of course, the same applies to information such as the pitch and angle of the “diffraction grating line”.

  As a method for forming the concavo-convex structure, not only a lithography method capable of forming a high-precision pattern such as the electron beam lithography and X-ray lithography described above, but also a high-precision uniform film thickness such as a metal thin film formation method is formed. Various thin film forming methods that can be used and methods for combining the patterning methods can be used. In this case, by increasing the surface smoothing accuracy of the substrate on which the thin film is formed, it is possible to create an ideal rectangle having few defects and a shape accuracy of nm level. Furthermore, due to its physical stability, heating and pressurization are possible during duplication, and the duplication accuracy to a resin or the like can be improved.

  The diffraction efficiency of the diffraction grating A is as follows. Each area (B1, B2, B3) of the diffraction grating B shown in FIG. 4 is a light source, an area with a period of 1.0 μm is a blue semiconductor laser, and an area with a period of 1.25 μm is green. When the area of the semiconductor laser and the period of 1.5 μm was measured by the red semiconductor laser, they were 4%, 6%, and 7%, respectively. When the entire diffraction grating B was illuminated with white light, each area was vividly observed divided into blue, green and red.

In addition, “A ○ C...” As a hidden character was read by a simple microscope (magnification 200 ×, 400 ×) as well as by visual observation, but it was not possible to read the character / symbol. However, it was clearly readable with a high-resolution laser microscope that had been adjusted to the specified setting.
Of course, higher resolution microscopes such as confocal laser microscopes, electron microscopes, transmission electron microscopes, scanning electron microscopes, scanning probe microscopes, atomic force microscopes, scanning tunneling microscopes, scanning near-field light microscopes, It can be used in a range that can be physically measured, such as an X-ray microscope. Furthermore, techniques for improving resolution such as confocal method and phase shift interferometry can also be used. By using an image processing method using a high-resolution CCD camera or the like for these microscopic images, the images can be joined together precisely to obtain information for a wide area. By using these, it is possible to improve the anti-counterfeiting property and improve the reliability of determination according to each feature.

However, the method for determining (or appraising) “authenticity” is not limited to the above-mentioned “method of reading a large amount of predetermined information”, but paying attention to one character, symbol, symbol or part thereof, and this one It is also possible to use a method in which characters, symbols, symbols or parts thereof are “precisely measured” and only the three-dimensional shape is used for “authenticity” determination.
In this case, do not make all the focused parts the same, but slightly deform (double the thickness or add a defect) and use the information for “authenticity” determination can do. In other words, the information used for the “authenticity” determination can be determined by the security management side (the voluntary nature further enhances the anti-counterfeiting property), and it can be assumed that the counterfeiter cannot make any analogy. Become.

The diffraction grating line (diffraction grating C) in FIG. 5 is an example in which the predetermined information is “H”.
“HHHHHHH...” Is formed along one diffraction grating line. A plurality of diffraction grating line groups formed in parallel with the “diffraction grating lines” have the same three-dimensional shape as the “diffraction grating lines” from end to end, and are viewed in the vertical direction described above. The characters on all the grid lines are arranged at the same position.
FIG. 6 shows the shape of the “diffraction grating line” along the line aa, and FIG. 7 shows the shape of the line bb. Both are rectangular.

FIG. 8 is a view of the diffraction grating C as viewed from above.
The height / width of the character is 0.75 μm × 0.4 μm (a diffraction grating with a period of 1.5 μm), which can be formed by electron beam lithography. The thickness of the electron beam resist is set to 0.3 μm, the electron beam is sufficiently applied, and after the development processing, the electron beam resist in the portion to which the electron beam is applied is completely removed, and the electron beam resist in the portion to which the electron beam is not applied substantially remains. It became a shape and could be a rectangle.

When this diffraction grating C was illuminated with a red semiconductor laser and the diffraction efficiency was measured, it was 10%, and a slightly higher diffraction efficiency could be obtained. When illuminated with white light, a bright red color could be observed.
The diffraction grating C has not only periodicity in a direction perpendicular to the “diffraction grating line” but also periodicity in a direction parallel to the “diffraction grating line”, so that the diffracted light is diffracted in the cross direction (next time). Folded light is diffracted in four directions), and diffracted light is also present in the diagonal direction (second-order diffracted light. There are four directions). Therefore, the diffracted light is dispersed in each direction, and diffraction efficiency in only one direction. The measured value is not so large.

  Further, since there are many diffracted light directions, it is not suitable for forming (designing) a color hologram image. This largely depends on the contrast of the set character “H” itself, and can be improved by using other characters and symbols such as “Q” and “&”. Moreover, the intensity | strength of only the desired diffracted light can also be improved by deform | transforming the font to employ | adopt and the character itself. The more concentrated the diffracted light is in a predetermined direction, the greater the diffraction efficiency in that direction.

  “HHH.. . This is largely due to the simplicity of “H” and can be improved by other characters and symbols.

The diffraction grating line (diffraction grating D) in FIG. 9 is also formed with the predetermined information “H”, and the height and width of the characters are 0.75 μm × 0.5 μm (a diffraction grating with a period of 1.5 μm). The method is also the same as that of the diffraction grating C, but its “H” is expressed in the form of a “white” character.
The shape of the “diffraction grating line” taken along the line aa is shown in FIG. As shown in FIG. 10, it is rectangular. Since the area of the character portion is 1/10 of the area to which the character is assigned, that is, the area of 0.75 μm × 0.5 μm, the line width of the character expressed in white is 1/30. FIG. 11 is a view of the diffraction grating D as viewed from above.

Therefore, the concave portion of the character portion appearing in the aa cross section is about 1/30 or less of the rectangle when there is no character (standard rectangle with a period of 1.5 μm), and the influence of the diffracted light from this concave portion. Is considerably smaller. As a result, the diffraction by the diffraction grating D was the same as the diffracted light by a rectangle (a standard rectangle having a period of 1.5 μm) when there was no character, and a large diffraction efficiency could be obtained.
When this diffraction grating D was illuminated with a red semiconductor laser and the diffraction efficiency was measured, it was 24%, and a high diffraction efficiency could be obtained. When illuminated with white light, a bright red color could be observed.

The diffraction light of the diffraction grating D is only in the two directions of the first-order diffracted light, and no second-order diffracted light was seen. For this reason, the diffracted light is not dispersed in each direction, and the measured value of diffraction efficiency in one direction is considerably large.
Although “HHH...” As a hidden character was to be read with a simple microscope (magnification 200 ×, 400 ×) as a matter of course, it was not possible to read the characters / symbols. Furthermore, the height / width of characters / symbols / designs can be reduced in order to reduce the area of white characters. Thereby, the readability of the predetermined information can be made more difficult, and the diffraction efficiency can be further improved. The ease of designing color hologram images has also been greatly improved.

  Further, when the predetermined information is “outlined”, the image line portion has a portion of 10 nm or less. In such a case, although there is a difference depending on the lithography means to be used, it may not be rectangular but may have a gentle uneven shape. In this case, since the width is very small, the diffraction efficiency as a “diffraction grating line” is not affected, and it can be read optically at the time of interpretation. Aim can be achieved.

  Conversely, by reducing the intensity of the electron beam in electron beam lithography, adjusting the development process to make the “white” itself less than 10 nm wide (in this case, the depth is also shallow). Then, it is also preferable to further improve security by using a technique in which the predetermined information cannot be read and can be read only using a means capable of three-dimensional measurement such as a laser microscope.

  Furthermore, since the illumination is performed only with “dark field” (high numerical aperture component (cone outer peripheral surface structure)) instead of observation with “bright field” provided in the optical microscope, basically “scattered light” It is also preferable to adopt a method in which slight unevenness is read as information by the observation in (1). As with `` dark field '', if a method of illuminating only from an oblique direction and interpreting the shadow of the convex portion generated at the convex portion as information is used, the forger can measure the uneven shape precisely, It is also possible to prevent the predetermined information from being reached.

The diffraction grating line (diffraction grating E) in FIG. 12 has a character height / width of 0.75 μm × 0.5 μm (a diffraction grating with a period of 1.5 μm), and the formation method is the same as that of the diffraction grating C. and was, but the area (image area area) occupied by the predetermined information "H", the area of a portion other than the predetermined information (non-image portions + of the "grating lines" the inter area) of the same size did.
In this way, since the area of the image area can be secured, it is easy to make an appraisal when appraising predetermined information, and at the same time, the predetermined information is special (thickness, bending, etc., used only in the present invention). By doing so, it is almost impossible to create the same object unless the setting information such as the character shape is known.

  By making the amount of light of the diffracted light reflected from the top surface of the image line portion, that is, the convex portion, and the light of the diffracted light reflected from the bottom surface of the non-image line portion + diffraction grating line, that is, the concave surface high, The diffraction efficiency can be increased. Actually, the diffraction efficiency was 16% because the second-order diffracted light as seen in the diffraction grating C was not generated. “HHH.. . This is largely due to the simplicity of the predetermined information “H”, and can be improved by using other characters and symbols.

In addition, the shape of the predetermined information itself is devised (various existing fonts may be adopted for the convenience of creating electronic drawing data, but the thickness of the image line, the bending method, etc. may be devised independently. Therefore, it is possible to further improve the legibility and diffraction efficiency.
As described above, when the shape of the predetermined information is devised, it is necessary to maintain the diffraction efficiency high by adjusting the depth of the predetermined information, that is, the thickness of the electron beam resist.

The diffraction grating line (diffraction grating F) in FIG. 13 has a character height / width of 0.75 μm × 0.5 μm (a diffraction grating with a period of 1.5 μm), and is formed in the same manner as diffraction grating C. However, the predetermined information is “HOLOG” (partially omitted in FIG. 13). In this way, the second-order diffracted light seen in the diffraction grating C or the like is suppressed, the intensity of the first-order diffracted light is increased, and the repetition of less than 20 characters makes it easy to predict the diffracted light, and the design of the color hologram image It was easy to do.
The shape of the aa cross section and the shape of the bb cross section are shown in FIGS. 14 and 15, respectively.
The diffraction efficiency was 12% because the second-order diffracted light unlike the diffraction grating C was not emitted.
“HOLOG” as a hidden character was read by a simple microscope (200 ×, 400 × magnification) as well as by visual observation, but it was not possible to read even characters and symbols.

  The intensity of the second-order diffracted light decreases as the number of letters increases, but it becomes sufficiently small with three letters (three times the visible light wavelength). When the number of characters is further increased, the number of characters gradually decreases, but there is no significant change with five or more characters. On the contrary, the unevenness on the “diffraction grating line” becomes conspicuous as the number of characters increases. This unevenness becomes an obstacle to the design of the color hologram image. Therefore, the character string has a limit of 20 characters. As a result, the repetition length of the predetermined information is preferably 20 times or less of the visible light wavelength, preferably 5 times or more and 10 times or less.

Example 1
An electron beam was irradiated along a predetermined diffraction grating pattern while changing the intensity of the electron beam according to control data prepared in advance on a pattern formation substrate on which an electron beam resist was formed to 0.6 μm. First, on the 0.5 μm width line, the predetermined information “A * C * E * G * I * .. * Y and its repetition” is set so that each character size is 0.5 μm × 0.5 μm. Subsequently, in contact with the “diffraction grating line”, the electron beam intensity change is reversed in the same manner as “A * C * E * G * H *. Were irradiated with the same size and with the start position adjusted with high accuracy. This irradiation was performed until the area was filled in one area of a circle with a radius of 20 mm in FIG.

Next, similarly, the same predetermined character was irradiated with a size of 0.625 μm × 0.5 μm on a 0.625 μm-width line, and the other area of the circle in FIG. 4 was similarly filled.
Furthermore, the remaining area in FIG. 4 was irradiated with a predetermined character of 0.75 μm × 0.5 μm size in a line of 0.75 μm width so that the area was filled, and the entire area in the circle in FIG. 4 was filled. .
The substrate was developed to obtain a desired uneven relief master.

Between this master and 16 μm thick polyethylene terephthalate (Toray “Lumilar”), as ionizing radiation curable resin,
・ <Ionizing radiation curable composition A>
2-hydroxyethyl acrylate 100 parts by weight Dibutyltin dilaurate 0.1 part by weight Ionizing radiation curable composition A obtained by reacting methyl isocyanate 50 parts by weight,
・ <Ionizing radiation curable composition B>
Ionizing radiation curable composition A 80 parts by weight Polyurethane resin (Desmocol 130, manufactured by Sumitomo Bayer Urethane Co., Ltd.) 20 parts by weight The above ionizing radiation curable composition B was prepared, and 10 μm of this ionizing radiation curable composition B was introduced. While sending out the film, an electron beam irradiation apparatus “Electro Curtain” (manufactured by ESI, USA) was used to irradiate with a dose of 3 Mrad under the conditions of 150 KeV and 15 mA to be cured.

After that, the master and the electron beam resist were peeled off and removed, and the fine irregularities of the relief hologram could be formed on one side of the layer made of a cured transparent resin material.
An aluminum thin film having a thickness of 100 nm was formed on the surface of the transparent resin by a vacuum deposition method to obtain a hologram sheet. An adhesive was applied to the hologram sheet and adhered so as to partially cover the face photograph of the passport.
When the hologram portion of this passport was illuminated with a halogen lamp and visually observed, the circular hologram was divided into three colors and looked clear. Furthermore, when it was enlarged and confirmed with a microscope with a magnification of 20 times and 400 times, predetermined information could not be read.

  By observing this hologram part with a high-resolution laser microscope, it is possible to read the predetermined information of each diffraction grating, and obtained in advance as top secret information (only the person who manages the passport has the size, arrangement, etc. of the predetermined information) Information (hereinafter referred to as “predetermined information related information”) is notified. The predetermined information related information is compared with the read information, and the authenticity of the passport is confirmed.

  Separately, when the diffraction efficiency of this hologram was measured using each color semiconductor laser, it was 4%, 6%, and 7%, respectively, and a slightly higher diffraction efficiency was obtained.

(Example 2)
An electron beam was irradiated along a predetermined diffraction grating pattern while changing the intensity of the electron beam according to control data prepared in advance on a pattern formation substrate on which an electron beam resist was formed to 0.3 μm. First, predetermined information “HHHHHHH...” Is placed on a line having a width of 0.5 μm so that each character size is 0.5 μm × 0.4 μm. An electron beam was irradiated on the entire surface in a 5 μm-wide line. This irradiation was carried out until one area of a circle with a radius of 20 mm in FIG.
Next, the electron beam resist is again 0.4 μm, and the same processing as in Example 1 is performed except that the same predetermined characters are irradiated on the 0.625 μm width line in a size of 0.625 μm × 0.4 μm. Filled another area of the circle of 4.
Furthermore, the remaining area in FIG. 4 was irradiated with a predetermined character of 0.75 μm × 0.4 μm in such a manner that the electron beam resist thickness was linear with a thickness of 0.5 μm and a width of 0.75 μm so that the area was filled. In the same manner as in Example 1, all the areas in the circle of FIG. 4 were filled.
By developing this base, the resist in the non-image area was completely removed, and the desired rectangular relief master was obtained with this position as the concave and concave bottom surface and the image area as the convex upper surface.

After that, the hologram forming passport of Example 2 was obtained in the same manner as in Example 1.
When the hologram portion of this passport was illuminated with a halogen lamp and visually observed, the circular hologram was divided into three colors and looked clear. Furthermore, when it was enlarged and confirmed with a microscope with a magnification of 20 times and 400 times, predetermined information could not be read.

By observing this hologram portion with a high-resolution laser microscope, it is possible to read the predetermined information of each diffraction grating, compare the read information with the information related to the predetermined information obtained in advance as confidential information, and authenticate the passport It was confirmed.
Separately, when the diffraction efficiency of this hologram was measured using each color semiconductor laser, it was 10%, 9%, and 10%, respectively, and a slightly high diffraction efficiency was obtained.

(Example 3)
A hologram forming passport of Example 3 was obtained in the same manner as Example 2 except that the predetermined information “HHHHHHH...” Was a white character and the image line width was 0.01 μm.
When the hologram portion of this passport was illuminated with a halogen lamp and visually observed, the circular hologram was divided into three colors and looked clear. Furthermore, when it was enlarged and confirmed with a microscope with a magnification of 20 times and 400 times, predetermined information could not be read at all.

By observing this hologram portion with a high-resolution laser microscope, it is possible to read the predetermined information of each diffraction grating, compare the read information with the information related to the predetermined information obtained in advance as confidential information, and authenticate the passport It was confirmed.
Separately, the diffraction efficiency of this hologram was measured using each color semiconductor laser, and high diffraction efficiencies of 25%, 23%, and 24% were obtained, respectively.

Example 4
A hologram formation passport of Example 4 was obtained in the same manner as in Example 2 except that the predetermined information “HHHHHHH... The area ratio at this time was 54/46.
When the hologram portion of this passport was illuminated with a halogen lamp and visually observed, the circular hologram was divided into three colors and looked clear. Furthermore, when it was confirmed by magnifying with a microscope with a magnification of 20 times and 400 times, the predetermined information could be inferred but could not be read.

By observing this hologram portion with a high-resolution laser microscope, it is possible to read the predetermined information of each diffraction grating, compare the read information with the information related to the predetermined information obtained in advance as confidential information, and authenticate the passport It was confirmed.
Separately, when the diffraction efficiency of this hologram was measured using each color semiconductor laser, high diffraction efficiencies of 13%, 13%, and 16% were obtained, respectively.

(Example 5)
A hologram formation passport of Example 5 was obtained in the same manner as Example 2 except that the predetermined information was “HOLOG and its repetition”.
When the hologram portion of this passport was illuminated with a halogen lamp and visually observed, the circular hologram was divided into three colors and looked clear. Furthermore, when it was enlarged and confirmed with a microscope with a magnification of 20 times and 400 times, predetermined information could not be read.

By observing this hologram portion with a high-resolution laser microscope, it is possible to read the predetermined information of each diffraction grating, compare the read information with the information related to the predetermined information obtained in advance as confidential information, and authenticate the passport It was confirmed.
Separately, the diffraction efficiency of this hologram was measured using each color semiconductor laser, and a slightly higher diffraction efficiency of 11%, 11%, and 12% was obtained, respectively.

(Comparative example)
As the predetermined information of Example 2, “HHHHHHH...” Was used, but the character size was selected at a random size between 0.3 μm and 3.0 μm for both the character height and character width, A comparative example was obtained in the same manner as in Example 2 except that the circular area in FIG.
When the hologram portion of this passport was illuminated with a halogen lamp and visually observed, the circular hologram was not divided into three colors, but only a little iridescent. Furthermore, when it was confirmed by magnifying with a microscope of 20 times and 400 times, predetermined information could be read in some places.

By observing this hologram portion with a high-resolution laser microscope, it is possible to interpret all the predetermined information of each diffraction grating, compare the information that has been obtained in advance with the information related to the predetermined information obtained as confidential information, and authenticate the passport. I was able to confirm the sex.
Separately, when the diffraction efficiency of this hologram was measured using a red semiconductor laser, a diffraction efficiency as low as 3% was obtained. This is presumably because light is diffracted in various directions and is not concentrated in one direction.
(Evaluation test) The evaluation of the reproducibility of the hologram was visually determined for the design property under a halogen lamp light source. The brightness of the hologram was evaluated by the diffraction efficiency of the diffraction grating.
Halogen lamp: Low bolt halogen lamp with 35mm diameter mirror
: Voltage 12V, luminous intensity 2300cd (candela)
Visual judgment criteria: ○ The reproduced image looks vivid and uniform. Hidden information is not visible.
: X Hidden information is not visible, but the playback image is dark and uneven. .
Diffraction efficiency measurement: Light source: Each color semiconductor laser: Kiko Giken MLX collimated laser
: Voltage DC 4.8-6.5V, beam diameter expansion 6mm at the time of parallel light
: Diffraction efficiency: reflected light intensity / incident light intensity * 100 (%)
: Criteria: A: High diffraction efficiency Diffraction efficiency 15% or more
: ○: Slightly high diffraction efficiency 〃 5% ~ 15%
: ×: Low diffraction efficiency 未 満 Less than 5%

These are overhead views of the diffraction grating A which shows an example of embodiment of this invention. These are the figures for demonstrating the aa line cross section of the diffraction grating A. FIG. These are figures of the diffraction grating body B which shows an example of embodiment of this invention. These are the figures which looked at the diffraction grating A from the top. These are overhead views of the diffraction grating C which shows an example of embodiment of this invention. These are the figures for demonstrating the aa line cross section of the diffraction grating C. FIG. These are the figures for demonstrating the bb line | wire cross section of the diffraction grating C. FIG. These are the figures which looked at the diffraction grating C from the top. These are overhead views of the diffraction grating D which shows an example of embodiment of this invention. These are the figures for demonstrating the aa line cross section of the diffraction grating D. FIG. These are the figures which looked at the diffraction grating D from the top. These are the figures which looked at the diffraction grating E which shows an example of embodiment of this invention from the top. These are overhead views of the diffraction grating F which shows an example of embodiment of this invention. These are the figures for demonstrating the aa line cross section of the diffraction grating F. FIG. These are the figures for demonstrating the bb line | wire cross section of the diffraction grating F. FIG.

Explanation of symbols

A, C, D, E, F Diffraction grating (Diffraction grating line group)
B Diffraction grating bodies B1, B2, B3 Each diffraction grating line group

Claims (3)

A diffraction grating having a relief shape with a period twice as long as a visible light wavelength, or a hologram composed of the diffraction grating,
Each of the diffraction grating lines constituting the diffraction grating is a predetermined character, symbol, design, or a combination of concavo-convex structures for displaying any combination information (hereinafter referred to as predetermined information), and While constituting the relief shape of the diffraction grating line group having a periodicity in the cross section in the vertical direction of the diffraction grating lines, the shape of the cross section has periodicity ,
The area of the predetermined information display area and the non-image area are the same, and the area of the non-image area is the sum of the area between the non-image area and the “diffraction grating” of the predetermined information display area. Characteristic diffraction grating or hologram. It said predetermined information is more than five times the wavelength of visible light, and a diffraction grating or hologram of claim 1, wherein the within 20 times the repetition length information. The diffraction grating or hologram according to claim 1 or 2, wherein the cross section is composed of a combination of a convex portion representing predetermined information and a concave portion that is point-symmetric with the convex portion.

Images