JP2022177038A - Hologram element, information recording medium, label body, transfer foil body, card and hologram sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate a Fourier-transform hologram-reproduced image and a volume-reflection hologram-reproduced image so as to allow observation.

SOLUTION: A hologram element comprises a hologram layer recorded by superimposing: a first interference fringe converted into a Fourier-transform hologram-reproduced image when light from a point light source disposed separated from an incident surface is made incident; and a second interference fringe converted to a volume-reflection hologram-reproduced image when playback illumination light is made incident on the incident surface along a direction that is inclined in relation to the normal direction of the incident surface.

SELECTED DRAWING: Figure 6A

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present disclosure relates to hologram elements, information recording media, label bodies, transfer foil bodies, cards, and hologram sheets.

A volume reflection hologram, also called a Lippmann hologram, selects and diffracts light of a specific wavelength when light is incident at a specific angle of incidence, so it has little chromatic dispersion and also produces interference fringes using the image hologram technique. By recording, it is possible to observe a three-dimensional image with little blur even in various light source environments, so it is widely used for the purpose of preventing counterfeiting. In addition, phase-type Fourier transform holograms using computer-generated hologram technology and imprint technology are widely used for the purpose of preventing counterfeiting, etc., because they can be mass-produced at low cost (Japanese Patent Application Laid-Open No. 2017-37272. publication).

Also, there is known a method of recording a Fourier transform hologram on a recording medium for recording the Lippmann hologram (hereinafter referred to as a Lippmann hologram recording medium) (Japanese Patent Application Laid-Open No. 2009-139676). In this type of technique, as shown in FIG. 13, an original image 76 of a Fourier transform hologram is arranged at the front focus of an optical lens 75, and a Lippmann hologram recording medium 77 is arranged at the rear focus of the optical lens 75. The interference fringes between the reference light and the object light generated from the original image 76 of the Fourier transform hologram are recorded on the Lippmann hologram recording medium 77 .

The spread angle θ of the Fourier transform hologram reconstructed image reproduced by irradiating the recording medium 77 recorded by the method shown in FIG. It is about the same as the maximum angle θmax of the ray with respect to the optical axis. The maximum angle θmax of the optical lens 75 increases as the effective aperture of the lens increases and as the focal length decreases.

The focal length f of the thin single lens 78 shown in FIG. 14 is expressed by the following equation (1) using the radius of curvature r1 of the front surface of the lens, the radius of curvature r2 of the rear surface of the lens, and the refractive index n.

When the plane side of the plano-convex lens is placed on the front surface of the lens, r1 is infinite, so it is approximated by equation (2).

JP 2017-37272 A

In the case of BK7, which is often used in optical glass, the refractive index n for light with a wavelength of 532 nm is n=1.519, and the maximum angle θmax in a plano-convex lens is expressed by sin θmax=1/2F. Here, F is the F value of the lens, and when D is the effective aperture of the lens, F=f/D. From the above conditions and formula, θmax≈31.26° is calculated. This is the case of a lens with an effective aperture of D=2r, and in practice it is difficult to achieve the maximum angle .theta.max up to this point in order to avoid the effects of lens aberration and the like. For example, when interference fringes are formed with a lens outer diameter of φ100 mm and a focal length of 200 mm, the divergence angle θ is about 5 to 10°, and the range of design is limited. In conventional Fourier transform holograms, in order to ensure visibility, it is assumed that a laser beam is irradiated during reproduction, and the reproduced image is projected onto a screen installed on the laser beam incident side for observation. I needed heavy equipment.

Also, when replicating a hologram from a master on which interference fringes of a Fourier transform hologram and interference fringes of a volume reflection hologram are formed, it is desirable to replicate using the same reference beam in consideration of efficiency in manufacturing. When a hologram element duplicated with the same reference beam is reproduced, the reproduced image of the Fourier transform hologram and the reproduced image of the volume reflection hologram overlap and are reproduced. For this reason, the Fourier transform hologram and the volume reflection hologram must be provided as separate recording areas in the hologram element, or the wavelength of the reference light must be different when recording, which makes the fabrication of the hologram element laborious. It takes.

In the present disclosure, it is possible to improve the workability of duplication from an original on which the interference fringes of a Fourier transform hologram and the interference fringes of a volume reflection hologram are formed, and to reproduce the Fourier transform hologram image and the volume reflection hologram reproduction image. A hologram element, an information recording medium, a label body, a transfer foil body, a card and a hologram sheet that can be observed separately from each other.

In order to solve the above problems, according to one aspect of the present disclosure, when light from a point light source arranged away from the incident surface is incident, the first image is converted into a Fourier transform hologram reconstruction image. The interference fringes and the second interference fringes that are converted into a volume reflection hologram reproduced image when the reconstruction illumination light is incident on the incident surface along a direction inclined with respect to the normal direction of the incident surface. A hologram element is provided comprising hologram layers recorded in superimposition. Since the first interference fringes and the second interference fringes are formed on the same hologram layer, the Fourier transform reconstruction image and the volume reflection hologram reconstruction image can be reconstructed under respectively suitable reconstruction illumination light conditions.

The incident direction of the reconstruction illumination light and the reconstruction direction of the volume reflection hologram reconstruction image may be in an off-axis relationship different from each other. Since the incident direction of the reconstruction illumination light and the reconstruction direction of the volume reflection hologram reconstruction image are different from each other, the volume reflection hologram reconstruction image can be observed without overlapping the reconstruction illumination light.

The Fourier transform hologram reproduced image is observed in the normal direction of the incident surface when the point light source is irradiated from the normal direction of the incident surface,
The volume reflection hologram reconstructed image is observed in the normal direction of the incident surface when the reconstruction illumination light is incident on the incident surface along a direction inclined with respect to the normal direction of the incident surface. may A Fourier transform hologram reconstruction image can be observed with the point light source, and a volume reflection hologram reconstruction image can be observed from a direction different from the incident direction with reconstruction illumination light different from the point light source.

The reproduced image of the Fourier transform hologram observed in the direction normal to the plane of incidence according to the incident angle of the reference light with respect to the direction normal to the plane of incidence when the second interference fringes were recorded in the hologram layer. may vary in color. By changing the incident angle of the reference light when recording the second interference fringes, it is possible to change the hue of the Fourier transform hologram reconstruction image.

The greater the incident angle of the reference light, the greater the change in hue of the Fourier transform hologram reconstruction image observed in the normal direction of the incident surface. By increasing the incident angle of the reference light, the hue of the Fourier transform hologram reconstruction image can be changed more greatly.

When the reproduction illumination light is incident on the incidence surface along a direction inclined with respect to the normal direction of the incidence surface, the incidence surface is observed along the specular direction of the reflected light of the reproduction illumination light. Then, the hue of the Fourier transform hologram reconstruction image may change. When the incident surface is observed from the specular reflection direction opposite to the incident direction of the reconstruction illumination light, the hue of the Fourier transform hologram reconstruction image can be changed.

In another aspect of the present invention, a first interference fringe that is converted into a Fourier transform hologram reconstruction image when light from a point light source arranged apart from an incident surface is incident; a hologram layer on which a second interference fringe is superimposed and recorded, which is converted into a volume reflection hologram reproduction image when the reproduction illumination light is made incident on the incident surface along a direction inclined with respect to the linear direction; prepared,
An information recording medium is provided in which at least one of the Fourier transform hologram reconstruction image and the volume reflection hologram reconstruction image contains predetermined information. Since the first interference fringes and the second interference fringes are formed on the same hologram layer, the Fourier transform reconstruction image and the volume reflection hologram reconstruction image can be reconstructed under respectively suitable reconstruction illumination light conditions. Predetermined information can be included in at least one of the reproduced image and the volume reflection hologram reproduced image.

In another aspect of the present disclosure, at least an adhesive layer, a hologram layer, and a protective film layer are sequentially laminated on a separator, and the hologram layer receives light from a point light source spaced apart from an incident surface. a first interference fringe that is converted into a Fourier transform hologram reconstruction image when the light is incident on the entrance surface; A label body is provided on which a second interference fringe converted into a reproduced image of a hologram is superimposed and recorded. Observation of Fourier transform reconstruction images and volume reflection hologram reconstruction images on various media by attaching a label having a hologram layer on which first interference fringes and second interference fringes are formed to various media. can.

In another aspect of the present disclosure, at least a hologram layer, a release layer, and a substrate layer are sequentially laminated on the heat seal layer, and the hologram layer receives light from a point light source spaced apart from the incident surface. When the first interference fringes are converted into a Fourier transform hologram reconstruction image when incident, and the reconstruction illumination light is incident on the incident surface along a direction inclined with respect to the normal direction of the incident surface. A transfer foil on which a second interference fringe converted into a volume reflection hologram reproduction image is superimposed and recorded is provided. By transferring the transfer foil provided with the hologram layer on which the first interference fringes and the second interference fringes are formed to various media, Fourier transform reconstruction images and volume reflection hologram reconstruction images can be obtained on various media. Observable.

In another aspect of the present disclosure, at least a heat seal layer, a hologram layer, a protective film layer, and an oversheet are sequentially laminated on a card core sheet, and the hologram layer is a point light source separated from an incident surface. a first interference fringe that is converted into a Fourier transform hologram reconstruction image when light from the incident surface is incident; A second interference fringe that is converted into a volume reflection hologram reproduced image when the second interference fringes are superimposed and recorded,
A card is provided in which at least one of the Fourier transform hologram reconstruction image and the volume reflection hologram reconstruction image contains predetermined information. Since the first interference fringes and the second interference fringes are formed in the hologram layer of the card, a card can be obtained in which the Fourier transform reconstruction image and the volume reflection hologram reconstruction image can be observed under suitable reconstruction illumination light conditions. .

A laser-printed layer may be provided between the card core sheet and the heat-sealable layer, the layer being altered by a laser beam of a predetermined frequency. Since the card is provided with not only the hologram layer but also the laser-printed layer, it is possible not only to observe the Fourier transform reproduced image and the volume reflection hologram reproduced image, but also to record arbitrary information on the laser-printed layer.

The laser-printed layer is arranged to cover the entire surface of the card core sheet,
The hologram layer may be arranged on part of the laser-printed layer. Since the laser-printed layer is arranged so as to cover the entire surface of the card core sheet, arbitrary information can be recorded in a place where the laser-printed layer does not overlap the hologram layer.

At least personal information may be recorded on the laser-printed layer by being partially altered by the laser beam. By irradiating the laser-printed layer with a laser beam, the laser-printed layer can be altered in quality such as discoloration, melting, carbonization, foaming, or coloring.

In another aspect of the present invention, at least a heat-seal layer, a hologram layer, a protective film layer, and an oversheet are sequentially laminated on a base sheet, and the hologram layer is spaced apart from the plane of incidence. First interference fringes that are converted into a Fourier transform hologram reconstruction image when light from a light source is incident, and reconstruction illumination light onto the incident surface along a direction inclined with respect to a normal direction of the incident surface. A second interference fringe that is converted into a volume reflection hologram reproduction image when incident is superimposed and recorded,
A hologram sheet is provided in which at least one of the Fourier transform hologram reconstruction image and the volume reflection hologram reconstruction image contains predetermined information. Since the first interference fringes and the second interference fringes are formed in the hologram layer of the hologram sheet, a Fourier transform reconstruction image and a volume reflection hologram reconstruction image can be observed by switching to respective reconstruction illumination light conditions.

In another aspect of the present invention, a hologram recording member having a photosensitive material layer is arranged on a master plate in which a substrate layer, a Fourier transform hologram layer, a reflective layer, an adhesive layer, and a volume reflection hologram layer are laminated. making the reference beam incident on the upper surface of the hologram recording member along a direction inclined with respect to the normal direction of the upper surface of the hologram recording member;
part of the reference light passes through the hologram recording member, is incident on the master, is diffracted by the volume reflection hologram layer, and generates first diffracted light;
the first diffracted light and the reference light interfere in the photosensitive material layer in the hologram recording member to form a first interference fringe;
a remaining portion of the reference light is transmitted through the volume reflection hologram layer and diffracted by the surface of the Fourier transform hologram layer to generate second diffracted light;
A hologram replication method is provided, wherein the second diffracted light and the reference light interfere with each other in the photosensitive material layer in the hologram recording member to form a second interference fringe. By irradiating the reference beam in a state in which the hologram recording member is placed on the master on which the Fourier transform hologram layer and the volume reflection hologram layer are laminated, a first interference fringe and a first interference fringe are formed in the photosensitive material layer in the hologram recording member. Since two interference fringes can be formed, holograms of uniform quality can be mass-produced at low cost.

According to the present disclosure, it is possible to improve the workability of duplication from an original on which interference fringes of a Fourier transform hologram and interference fringes of a volume reflection hologram are formed, and to reproduce a Fourier transform hologram image and a volume reflection hologram. The reproduced image can be observed separately.

FIG. 2 is a cross-sectional view showing the cross-sectional structure of an original plate for producing the hologram element according to the present embodiment; The figure explaining the process of a two-step method. The figure explaining the process following FIG. 2A. 1 is a diagram showing a schematic configuration of a copier; FIG. FIG. 2 is a cross-sectional view of a state in which a hologram recording member is arranged on the upper surface of the master; The figure which shows an example of the Fourier-transform hologram reproduction image in the case of the incident angle of 30 degrees. FIG. 4 is a diagram showing an example of a Fourier transform hologram reconstruction image when the incident angle is 40°; FIG. 4 is a diagram for explaining a method of reproducing a Lippmann hologram reproduced image; FIG. 4 is a diagram for explaining a method of reproducing a Fourier transform hologram reproduction image; The xy chromaticity diagram which shows the evaluation result of the Fourier-transform hologram reproduction image. FIG. 8 is a diagram showing a hologram element used for the evaluation of FIG. 7; FIG. 8 is a diagram showing measurement points of a Fourier transform hologram reconstruction image used for the evaluation of FIG. 7; A cross-sectional view of a label having a hologram element according to the present embodiment. FIG. 3 is a cross-sectional view of a transfer foil provided with a hologram element according to this embodiment; FIG. 2 is a cross-sectional view of a card-embedded body having a hologram element according to the present embodiment; Top view of the card. A cross-sectional view of a card. Cross-sectional view of a card with an additional laser-printed layer. FIG. 4 is a diagram for explaining a method of recording a Fourier transform hologram on a Lippmann hologram recording medium; The figure explaining the curvature radius of a thin single lens.

Embodiments of the present disclosure will be described below with reference to the drawings. In addition, in the drawings attached to this specification, for the convenience of easy understanding of the drawings, there are cases where the reduced scale, vertical and horizontal dimension ratios, etc. are changed and exaggerated from those of the actual ones.

In addition, terms such as "parallel", "perpendicular", "identical", etc. that specify shapes and geometric conditions and their degrees used in this specification are not bound by a strict meaning, It is interpreted to include the extent to which similar functions can be expected.

In addition, the "vertical direction" in this specification is a direction non-parallel to the horizontal direction within a plane parallel to the vertical direction, and does not necessarily match the vertical direction. "Upper" refers to one side in the vertical direction and the side (or direction) closer to "upper" in the vertical direction. "Lower" refers to the side (or direction) opposite to "upper" in the vertical direction and closer to "lower" in the vertical direction.

Also, in this specification, terms such as "sheet", "film", and "plate" are not to be distinguished from each other based only on the difference in names. Therefore, for example, "sheet" is a concept that includes members that can be called films and plates.

FIG. 1 is a cross-sectional view showing the cross-sectional structure of an original plate 2 for producing a hologram element according to this embodiment. The original plate 2 of FIG. 1 comprises a glass layer 3, an adhesive layer 4, a substrate layer 5, a surface relief Fourier transform hologram layer 6, a reflective layer 7, a transparent adhesive layer 8, a Lippmann hologram layer 9, and a cover glass 10 which are laminated in this order. It is what I did.

The preparation of the surface relief type Fourier transform hologram layer 6 (hereinafter referred to as the Fourier transform hologram layer 6) and the preparation of the Lippmann hologram layer 9 in the original plate 2 are performed separately. The original plate 2 shown in FIG. 1 is produced by bonding the hologram layers in the layer direction.

The Fourier transform hologram layer 6 is produced by CGH (Computer-Generated Hologram), for example. More specifically, the Fourier transform image from which the Fourier transform hologram layer 6 is produced is generated by subjecting the original image to processing such as Fourier transform using a computer, for example. Specifically, first, an original image is generated on a personal computer (PC). The original image is any character, symbol, pattern, or the like. Next, the Fourier transform image is binarized. That is, the phase of each pixel of the Fourier transform image is examined, and if the phase is between minus 90 degrees and plus 90 degrees, a predetermined value corresponding to transparency is assigned. Binarization is performed by assigning a corresponding alternative value. Note that the phase range to which the predetermined value is assigned may be set outside the range of minus 90 degrees to plus 90 degrees.

Next, the binarized Fourier transform images are arranged in a desired range. For example, a Fourier transform image is generated by arranging four binarized Fourier transform images. In practice, a Fourier transform image is generated by, for example, arranging 20 minimum unit images vertically and horizontally. Next, the generated Fourier transform image is converted into electron beam drawing data, and a Fourier transform hologram layer 6 is produced by an electron beam drawing apparatus based on the converted electron beam drawing data. The produced Fourier transform hologram layer 6 has unevenness corresponding to the Fourier transform image. Note that the Fourier transform image may be multi-valued. In this case, the unevenness of the Fourier transform hologram layer 6 has three or more steps. The grating pitch of the unevenness of the Fourier transform hologram layer 6 is preferably within the range of 1.0 μm to 80.0 μm.

A reflective layer 7 is formed on the uneven surface of the generated Fourier transform hologram layer 6 . The reflective layer 7 is, for example, a deposited film of aluminum, zinc sulfide, titanium oxide, or the like. The reflective layer 7 is desirably made of a material that reflects visible light or has a refractive index as high as possible. By forming the reflective layer 7 on the uneven surface of the Fourier transform hologram layer 6, the light incident on the master 2 is diffracted by the reflective layer 7, so that the reproduced Fourier transform hologram image can be reproduced.

On the other hand, the Lippmann hologram layer 9 is produced by, for example, a two-step method (also called H1H2 method). 2A and 2B are diagrams illustrating the steps of the two-step method. First, as shown in FIG. 2A, a photosensitive material 11 is prepared, and an object light L2 reflected by the object 12 when an object 12, which is spaced apart from the photosensitive material 11, is irradiated with the illumination light L1 is projected onto the photosensitive material 11. 11, the photosensitive material 11 is irradiated with the reference light L3 from a direction different from the direction of the object light L2. As a result, the object light L2 and the reference light L3 interfere with each other on the photosensitive material 11 to form interference fringes, and the H1 hologram 13 is produced. When forming a plurality of interference fringes corresponding to a plurality of subjects 12 on the photosensitive material 11, the process of FIG. 2A may be repeated for each subject 12. FIG. At this time, by making the distances between the subjects 12 and the photosensitive material 11 equal and by varying the irradiation range of the object light L2 on the photosensitive material 11 for each subject 12, the light beams are projected onto different locations on the photosensitive material 11. A plurality of interference fringes corresponding to each subject 12 can be formed. The reference light is coherent laser light, and for example, laser light emitted from a DPSS (Diode Pumped Solid State) laser that oscillates at 532 nm can be used as the reference light.

Next, as shown in FIG. 2B, the H1 hologram 13 is irradiated with reconstruction illumination light L4 traveling in the opposite direction to the reference light L3 from the side opposite to the incident side of the reference light L3. As a result, the object light L5 is emitted from the H1 hologram 13, and a reconstructed image 12a is formed at a position separated by the distance between the H1 hologram 13 and the object 12. FIG. Therefore, the photosensitive material 14 is arranged at this position, and the reference light L6 is irradiated from the side opposite to the H1 hologram 13. FIG. As a result, the reference light L6 and the object light L5 interfere with each other on the photosensitive material 14 to form interference fringes, and the H2 hologram 15 is produced. This H2 hologram 15 becomes the Lippmann hologram layer 9 .

The Fourier transform hologram layer 6 and the Lippmann hologram layer 9 produced in the steps of FIGS. 2A and 2B are bonded in the layer direction with a transparent adhesive layer 8 as shown in FIG. The Lippmann hologram layer 9 is preferably arranged closer to the light incident surface than the Fourier transform hologram layer 6 is. The reason for this is that the reflection layer 7 is formed on the upper surface of the Fourier transform hologram layer 6, and if the Lippmann hologram layer 9 is arranged below the Fourier transform hologram layer 6, the light does not reach the Lippmann hologram layer 9. It's for. A part of the reflective layer 7 covering the surface of the Fourier transform hologram layer 6 may be partially removed by demetallizing. In this case, as an exception, the Lippmann hologram layer 9 can be arranged below the Fourier transform hologram layer 6 .

As shown in FIG. 1, when the Lippmann hologram layer 9 is arranged on the incident light side of the Fourier transform hologram layer 6, a cover glass 10 is arranged on the surface of the Lippmann hologram layer 9 to protect the Lippmann hologram layer 9. do. Further, a substrate layer 5 is arranged on the opposite side of the Fourier transform hologram layer 6 to the Lippmann hologram layer 9 side, and a glass layer 3 is arranged on the surface of the substrate layer 5 with an adhesive layer 4 interposed therebetween. there is This glass layer 3 functions as a protective layer. The substrate layer 5 may be arranged on the Lippmann hologram layer 9 side with respect to the Fourier transform hologram layer 6 .

The master 2 of FIG. 1 is duplicated on a hologram recording member 22 using a duplicator 21 as shown in FIG. The copying machine 21 shown in FIG. and a take-out portion 28 .

The recording member supply unit 23 supplies the hologram recording member 22 guided by the nip rollers 29 from the roll body 23a on which the hologram recording member 22 to which the separator 22a is stuck is wound in multiple layers. The peeling supply head 24 peels off the separator 22 a from the hologram recording member 22 . A lamination roller 35 affixes the recording member 22 to the original 2 . The first separator winding section 25 winds up the peeled separator 22a. The recording member winding section 26 winds up the hologram recording member 22 after duplication. The protective film extractor 27 supplies a protective film 27a to be attached to the surface of the hologram recording member 22 that has been duplicated. When the separator 27b is attached to the protective film 27a, the second separator winding section 28 winds up the separator 27b.

In the duplicating machine 21 of FIG. 3, the hologram recording member 22 is moved frame by frame from the recording member supply unit 23, and after the separator 22a is peeled from the hologram recording member 22, the peeling supply head 24 moves leftward. One frame of the hologram recording member 22 is attached to the upper surface of the master 2 by the lamination roller 35 . FIG. 4 is a sectional view showing a state in which the hologram recording member 22 is arranged on the upper surface of the master 2. As shown in FIG. The hologram recording member 22 has a layer structure in which a base layer 32 is arranged on a photosensitive material layer 31 . In this state, the reference beam L7 is incident along a direction inclined with respect to the normal direction of the surface of the hologram recording member 22 . This reference light L7 is transmitted through the hologram recording member 22 and is incident on the master 2. As shown in FIG. A part of the reference light L7 is diffracted by the Lippmann hologram layer 9 inside the master 2, and this diffracted light and the reference light L7 interfere with each other at the photosensitive material layer 31 in the hologram recording member 22 to form interference fringes. It is formed. Another part of the reference light L7 is transmitted through the Lippmann hologram layer 9 and diffracted by the reflection layer 7 formed on the uneven surface of the Fourier transform hologram layer 6. This diffracted light and the reference light L7 interfere in the photosensitive material layer 31 in the hologram recording member 22 to form interference fringes.

Thus, in the photosensitive material layer 31 of the hologram recording member 22, the interference fringes (second interference fringes) from the Lippmann hologram layer 9 and the interference fringes (first interference fringes) from the Fourier transform hologram layer 6 are superimposed. formed by

When duplication for one frame is completed, the peeling supply head 24 moves rightward in FIG. On the surface of the hologram recording member 22 for one frame, a protective film 27a drawn out from a protective film feeding section 27 is pressed by a nip roller 33 and then wound up by a recording member winding section 26. FIG. At this time, one frame of the separator 22 a is peeled off from the hologram recording member 22 and wound up by the first separator winding section 25 . Next, by moving the peeling supply head 24 leftward, a new hologram recording member 22 for one frame is arranged on the master 2 . Through the steps described above, the hologram element 1 according to the present embodiment is produced by the copying machine 21 shown in FIG.

In this way, the duplicator 21 of FIG. 3 uses the same reference beam L7 to reproduce the interference fringes corresponding to the Lippmann hologram layer 9 and the Fourier transform hologram layer 6 of the master 2 onto the hologram recording member. Since the hologram element 1 according to the present embodiment is formed by being superimposed on 22 identical photosensitive members, the hologram element 1 according to the present embodiment can be efficiently manufactured, workability is improved, and mass production can be performed with uniform quality.

By controlling the incident angle of the reference light L7 with respect to the direction normal to the surface of the hologram recording member 22, the hue of the Fourier transform hologram reconstruction image can be adjusted. 5A and 5B are diagrams showing examples of Fourier transform hologram reconstruction images, FIG. 5A showing an example with an incident angle of 30° and FIG. 5B showing an example with an incident angle of 40°. Although FIGS. 5A and 5B are illustrated in monochrome, it is difficult to understand, but FIG. 5A is visually recognized in green, while FIG. 5B is visually recognized in reddish color. Also, in FIG. 5B, it can be seen that chromatic dispersion occurs.

On the other hand, the reproduced image of the Lippmann hologram (also referred to as the reproduced image of the volume reflection type hologram) does not change in color even if the incident angle of the reference light L7 during duplication is changed.

6A and 6B are diagrams for explaining a method of reproducing the hologram element 1 according to the present embodiment. FIG. 6A shows a method of reproducing a reproduced Lippmann hologram image 41, and FIG. 6B shows a method of reproducing a reproduced Fourier transform hologram image 42. FIG. there is The hologram element 1 of FIGS. 6A and 6B is formed on both sides of a hologram layer 45 formed by superimposing the interference fringes converted into the Fourier transform hologram reproduction image 42 and the interference fringes converted into the Lippmann hologram reproduction image 41. It has a cross-sectional structure in which PET (Polyethylene Terephthalate) layers 46 and 47 are laminated. The PET layers 46 and 47 function as protective layers for the hologram layer 45 . A protective layer may be formed using a material other than the PET layers 46 and 47 that is transparent to visible light.

When reproducing the Lippmann hologram reconstruction image 41, as shown in FIG. The observer directs his line of sight in the direction normal to the surface of the hologram element 1 . Thereby, the observer can observe the Lippmann hologram reconstruction image 41 in the vicinity of the surface of the hologram element 1 .

The reproduction illumination light L8 is LED (Light Emitting Diode) light, laser light, incandescent light, or the like, and basically any type of light source 43 is available. However, the light must include the wavelength of the color component of the Lippmann hologram reconstruction image 41 . For example, when the Lippmann hologram reconstruction image 41 is green, it is necessary to irradiate the reconstruction illumination light L8 including the green wavelength band. If the wavelength component of the reconstruction illumination light L8 does not include the wavelength of the color component of the Lippmann hologram reconstruction image 41, the Lippmann hologram reconstruction image 41 cannot be observed from a predetermined direction. Note that the incident angle of the reproduction illumination light L8 may be slightly different from the incident angle of the reference light L7 used for duplication.

Even when the observer directs the line of sight to the hologram element 1 from a direction inclined from the normal direction of the surface of the hologram element 1, the observer observes the Lippmann hologram reproduced image 41 of the same color as observed from the normal direction. be able to.

The direction of the specular reflection light of the reconstruction illumination light L8 and the reconstruction direction of the Lippmann hologram reconstruction image 41 are in a mutually different off-axis relationship. Here, "off-axis" means that the axis is off, and indicates that the direction of the specular reflection light of the reconstruction illumination light L8 and the reconstruction direction of the volume reflection hologram reconstruction image 41 are different from each other. On the other hand, the direction of the specular reflection light of the reconstruction illumination light L8 and the reconstruction direction of the Fourier transform hologram reconstruction image 42 are the same.

When reproducing Fourier transform hologram image 42, as shown in FIG. The line of sight is directed in the normal direction of Thereby, the observer can observe the Fourier transform hologram reconstruction image 42 in the same plane as the mirror image (reflected light) of the point light source reflected behind the surface of the hologram element 1 . The point light source 44 is LED light, laser light, incandescent light, or the like, and basically any specific type of the point light source 44 does not matter. However, the light must include the wavelength of the color component of the Fourier transform hologram reproduction image 42 .

The interference fringes for reproducing the Fourier transform hologram reproduction image 42 have wavelength selectivity, and even if the reproduction illumination light L9 is, for example, white light, it can be reproduced with monochromatic light. Further, the hue of the Fourier transform hologram reconstruction image 42 changes depending on the incident angle of the reference light L7 during duplication. More specifically, the greater the incident angle of the reference light L7 with respect to the normal direction of the surface of the hologram recording member during replication, the greater the degree of color change in the reproduced Fourier transform hologram image 42 . Furthermore, the hue of the Fourier transform hologram reconstruction image 42 also changes by changing the incident angle and observation direction of the reconstruction illumination light in the reconstruction stage.

FIG. 7 is an xy chromaticity diagram showing evaluation results of a Fourier transform hologram reconstruction image 42 reproduced by irradiating the hologram element 1 duplicated by the duplicating machine 21 of FIG. 3 with the reproduction illumination light L9, and FIGS. It is a figure which shows conditions. The closer to the G point in the xy chromaticity diagram of FIG. 7, the closer the color is to green, the closer to the B point, the closer to blue, and the closer to the R point, the closer to red.

The xy chromaticity diagram of FIG. 7 shows evaluation results using a color luminance meter (CS-200 manufactured by Konica Minolta). In the chromaticity distribution diagram of FIG. 7, as shown in FIG. 8A, when the reconstruction illumination light L9 is irradiated at an incident angle of 20° with respect to the normal direction of the surface of the hologram element 1, Chromaticity at measurement point P of Fourier transform hologram reconstruction image 42 shown in FIG. More specifically, the xy chromaticity diagram of FIG. 7 plots the chromaticities when the incident angles of the reference light L7 during duplication are 0°, 10°, 20°, 30°, 40°, and 50°. ing.

As can be seen from the xy chromaticity diagram of FIG. 7, the larger the incident angle of the reference light L7 during replication, the reddish the Fourier transform hologram reproduced image 42 becomes. The reproduced image 42 becomes greenish.

By adjusting the incident angle of the reference light L7 during duplication in this manner, the hue of the Fourier transform hologram reproduced image 42 can be optimized. Moreover, depending on the incident angle of the reference light L7, chromatic dispersion occurs in which the hue of the Fourier transform hologram reconstruction image 42 is partially different. Due to this chromatic dispersion, at least part of the Fourier transform hologram reconstruction image 42 may be observed in gradation colors.

The Fourier transform hologram reconstruction image 42 and the Lippmann hologram reconstruction image 41 may contain arbitrary information such as characters, symbols, patterns, and pictures. As a specific example, the Fourier transform hologram reconstruction image 42 and the Lippmann hologram reconstruction image 41 may contain security information including characters, symbols, patterns, and pictures. This type of security information can be used, for example, for anti-counterfeiting applications.

The hologram element 1 according to this embodiment can be used for various purposes. Typical uses of the hologram element 1 according to the present embodiment include hologram sheets used as labels, transfer foils, card embedding bodies, and information recording media, but it can also be applied to various other uses. is.

FIG. 9 is a cross-sectional view of a label body 51 having the hologram element 1 according to this embodiment. 9 has a cross-sectional structure in which an adhesive layer 53, a black colored PET layer 54, an adhesive layer 55, and a separator 56 are laminated in this order below a hologram layer 45 whose surface is covered with a protective film layer 52. . In the hologram layer 45, the interference fringes converted into the Fourier transform hologram reproduction image 42 and the interference fringes converted into the Lippmann hologram reproduction image 41 are superimposed and formed. After bonding the protective film layer 52 to the hologram layer 45 and curing the hologram layer 45 with UV light, the black colored PET layer 54 is adhered via the adhesive layer 53 , and then further via the adhesive layer 55 . , the separator 56 is adhered. The separator 56 is peeled off when the label body 51 is attached to various media. Note that, between the layers shown in FIG. 9, functional layers (not shown) having functions such as adhesion improvement and peelability may be interposed as necessary.

FIG. 10 is a cross-sectional view of a transfer foil body 61 having the hologram element 1 according to this embodiment. The transfer foil 61 of FIG. 10 comprises a substrate layer 69 with a release layer 62 adhered over the hologram layer 45 and a heat seal layer 63 positioned below the hologram layer 45 . When the transfer foil 61 of FIG. 10 is placed on various media and thermally pressed onto the substrate layer 69, the heat seal layer 63 is thermally melted and the hologram layer 45 is adhered to the media. After that, the base material layer 69 is peeled off. Thereby, the hologram layer 45 can be transferred onto the medium. In addition, between each layer shown in FIG. 10, a functional layer (not shown) having functions such as adhesion improvement and peelability may be interposed as necessary.

FIG. 11 is a sectional view of a hologram sheet used as a card embedding body 65 having the hologram element 1 according to this embodiment. 11, the heat seal layer 67 is arranged below the hologram layer 45 whose surface is covered with the protective film layer 66, and the separator 68 is arranged below it. 12A is a plan view of the card 70, and FIG. 12B is a cross-sectional view of the card 70. FIG. The card embedding body 65 of FIG. 11 is embedded within the card 70 . When embedding in the card 70, the separator 68 is peeled off from the card embedding body 65, and the card oversheet 72 is laminated while the heat seal layer 67 is in contact with the card core sheet 71, and is thermocompressed from above. As a result, the heat seal layer 67 is thermally melted and the hologram layer 45 is adhered to the card core sheet 71 . Alternatively, the card core sheet 71 may be provided with a recess and the card embedding body 65 may be placed there. Note that, between the layers shown in FIG. 11, functional layers (not shown) having functions such as adhesion improvement and peelability may be interposed as necessary.

The hologram sheet used as the card embedding body 65 or the like may have a laser-printed layer 73 in addition to the layer structure shown in FIG. 12B. FIG. 12C is a cross-sectional view of a card embedding body 65 having a laser-printed layer 73. FIG. The card embedding body 65 of FIG. 12C has a layer structure in which a laser printed layer 73 is arranged between the heat seal layer 67 and the card core sheet 71 of the card embedding body 65 of FIG. 12B. The laser-printed layer 73 is a layer that undergoes alteration such as discoloration, melting, carbonization, foaming, or coloring when irradiated with a laser beam. The laser-printed layer 73 may be made of polycarbonate resin, for example. The laser-printed layer 73 is formed so as to cover the entire surface of the card core sheet 71 . A laser beam is irradiated from the upper surface side of the card oversheet layer 72 . An infrared (IR) laser is normally used for laser marking on the laser marking layer 73 . Since the IR laser does not affect the hologram layer 45, it is also possible to perform laser printing on the regions of the laser-printed layer 73 that overlap the hologram layer 45 above and below.

According to the card embedded body 65 of FIG. 12C , the hologram layer 45 can reproduce the Lippmann hologram reproduction image 41 and the Fourier transform hologram reproduction image 42 , while the laser printing layer 73 can reproduce arbitrary characters, symbols, patterns, pictures, etc. can be printed. For example, in the example of FIG. 12A, the Lippmann hologram reconstruction image 41 and the Fourier transform hologram reconstruction image 42 can be reproduced in the card embedded body 65 on the upper right, and any place other than the card embedded body 65 (for example, indicated by X ) can be printed by the laser printing layer 73 . Any information may be recorded on the laser-printed layer 73. For example, at least personal information may be recorded by partial alteration by laser light.

The card 70 may be recorded with personal information or confidential information, may be recorded with information that can be exchanged for money, or may be used for other purposes. More specifically, the card 70 can be applied to various types of IC cards, cards with identification functions such as driver's licenses, insurance cards, membership cards, credit cards, debit cards, security cards with key functions, and the like. be.

Moreover, the hologram element 1 according to the present embodiment may be incorporated in information recording media of various sizes, not limited to the card 70 . The information recording medium is a medium recording various types of information such as banknotes, ID cards, passports, cash vouchers, tickets, public documents, personal information, confidential information, etc., or a medium having monetary value. ID cards include national ID cards, driver's licenses, membership cards, employee ID cards, student ID cards, and the like.

As described above, in the present embodiment, with the hologram recording member 22 placed on the original plate 2 shown in FIG. The interference fringes for reproducing the Fourier transform hologram reconstruction image 42 and the interference fringes for reproducing the Lippmann hologram reconstruction image 41 can be superimposed and recorded on the photosensitive material layer 31 in 22 . When a point light source 44 is arranged at a position separated from the surface of the hologram element 1 thus formed and the point light source 44 is turned on, a Fourier transform hologram reconstruction image 42 can be observed. Further, when the reconstruction illumination light L8 is incident along a direction inclined with respect to the normal direction of the hologram element 1, the Lippmann hologram reconstruction image 41 can be observed. In this way, by changing the irradiation method of the reconstruction illumination light beams L8 and L9, the Lippmann hologram reconstruction image 41 and the Fourier transform hologram reconstruction image 42 can be reconstructed with the same hologram layer 45. FIG.

Aspects of the present disclosure are not limited to the individual embodiments described above, but include various modifications that can be conceived by those skilled in the art, and the effects of the present disclosure are not limited to the above-described contents. That is, various additions, changes, and partial deletions are possible without departing from the conceptual idea and spirit of the present disclosure derived from the content defined in the claims and equivalents thereof.

REFERENCE SIGNS LIST 1 hologram element 2 original plate 3 glass layer 4 adhesive layer 5 substrate layer 6 surface relief Fourier transform hologram layer 7 reflective layer 8 transparent adhesive layer 9 Lippmann hologram layer 10 cover glass 11 photosensitive material , 12 subject, 13 H1 hologram, 14 photosensitive material, 15 H2 hologram, 21 duplicator, 22 hologram recording member, 22a separator, 23 recording member supply unit, 23a roll body, 24 peeling supply head, 25 first separator winding unit , 26 recording member winding portion, 27 protective film delivery portion, 27a protective film, 27b separator, 31 photosensitive material layer, 32 base layer, 33 nip roller, 41 Lippmann hologram reproduced image, 42 Fourier transform hologram reproduced image, 43, 44 light source, 45 hologram layer, 46, 47 PET layer, 51 label body, 52 protective film layer, 53 adhesive layer, 54 PET layer, 55 adhesive layer, 56 separator, 61 transfer foil body, 62 release layer, 63 heat seal layer , 65 card embedded body, 66 protective film layer, 67 heat seal layer

Claims (14)

A first interference fringe converted into a Fourier transform hologram reconstruction image when a first light from a point light source spaced apart from an incident surface is incident, and a first interference fringe that is inclined with respect to a normal direction of the incident surface. A second interference that is converted into a volume reflection hologram reproduced image when a second light from an optical axis direction different from the optical axis direction of the first light is incident on the incident surface along the direction of the second light A hologram element comprising a hologram layer in which fringes are superimposed and recorded. 2. The hologram element according to claim 1, wherein the incident direction of said second light and the reproduction direction of said volume reflection hologram reproduction image are in a mutually different off-axis relationship. The Fourier transform hologram reproduced image is observed in the normal direction of the incident surface when the first light from the point light source is irradiated from the normal direction of the incident surface,
The volume reflection hologram reproduced image is observed in the normal direction of the incident surface when the second light is incident on the incident surface along a direction inclined with respect to the normal direction of the incident surface. 3. The hologram element according to claim 1, wherein the hologram element is The reproduced image of the Fourier transform hologram observed in the direction normal to the plane of incidence according to the incident angle of the reference light with respect to the direction normal to the plane of incidence when the second interference fringes were recorded in the hologram layer. 4. The hologram element according to claim 3, wherein the color of the hologram element changes. 5. The hologram element according to claim 4, wherein the larger the incident angle of the reference light, the greater the change in hue of the reproduced Fourier transform hologram image observed in the normal direction of the plane of incidence. observing the incident surface along the direction of the reflected light of the second light when the second light is incident on the incident surface along a direction inclined with respect to the normal direction of the incident surface; 6. The hologram element according to any one of claims 1 to 5, wherein a color tone of said Fourier transform hologram reproduction image changes accordingly. A first interference fringe converted into a Fourier transform hologram reconstruction image when a first light from a point light source spaced apart from an incident surface is incident, and a first interference fringe that is inclined with respect to a normal direction of the incident surface. A second interference fringe that is converted into a volume reflection hologram reproduced image when a second light different from the first light is incident on the incident surface along the direction of the first light is superimposed and recorded. Equipped with a holographic layer,
At least one of the Fourier transform hologram reconstruction image and the volume reflection hologram reconstruction image includes predetermined information. At least, an adhesive layer, a hologram layer, and a protective film layer are sequentially laminated on a separator, and the hologram layer forms a Fourier transform hologram when a first light from a point light source arranged away from an incident surface is incident. First interference fringes converted into a reproduced image, and second light from an optical axis direction different from the optical axis direction of the first light along a direction inclined with respect to the normal direction of the incident surface. a second interference fringe that is converted into a volume reflection hologram reproduced image when incident on the incident surface, and a second interference fringe that is superimposed and recorded. At least, a hologram layer, a peeling layer, and a substrate layer are sequentially laminated on the heat seal layer, and the hologram layer is placed away from the incident surface. A first interference fringe converted into a Fourier transform hologram reconstruction image and a first interference fringe from an optical axis direction different from the optical axis direction of the first light along a direction inclined with respect to the normal direction of the incident surface. 2. A transfer foil on which a second interference fringe that is converted into a volume reflection hologram reproduced image when the light of No. 2 is incident on the incident surface is superimposed and recorded. At least, a heat seal layer, a hologram layer, a protective film layer, and a card oversheet are sequentially laminated on the card core sheet, and the hologram layer receives the first light from a point light source spaced apart from the incident surface. A first interference fringe that is converted into a Fourier transform hologram reconstruction image when incident, and light that is different from the optical axis direction of the first light along a direction that is inclined with respect to the normal direction of the incident surface. A second interference fringe that is converted into a volume reflection hologram reproduced image when the second light from the axial direction is incident on the incident surface is superimposed and recorded,
The card, wherein at least one of the Fourier transform hologram reconstruction image and the volume reflection hologram reconstruction image contains predetermined information. 11. The card according to claim 10, further comprising a laser-printed layer interposed between the card core sheet and the heat-sealing layer and altered by a laser beam of a predetermined frequency. The laser-printed layer is arranged to cover the entire surface of the card core sheet,
12. The card of Claim 11, wherein the holographic layer is disposed over a portion of the laser printed layer. 12. The card according to claim 11, wherein at least personal information is recorded on said laser-printed layer by being partially altered by said laser beam. At least, a heat seal layer, a hologram layer, a protective film layer, and an oversheet are sequentially laminated on the base sheet, and the hologram layer receives the first light from a point light source spaced apart from the incident surface. and an optical axis different from the optical axis direction of the first light along a direction inclined with respect to the normal direction of the incident surface. A second interference fringe that is converted into a volume reflection hologram reproduced image when a second light from a direction is incident on the incident surface is superimposed and recorded,
A hologram sheet, wherein at least one of the Fourier transform hologram reconstruction image and the volume reflection hologram reconstruction image contains predetermined information.

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