JPS6323275B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for duplicating a hologram, in which interference fringes in a concave-convex pattern are recorded on a photosensitive material by interfering with two or more beams of light, and this is used as a hologram original plate to produce an image. The present invention relates to a method of replicating a hologram by casting.

Traditionally, various decorations have been applied to easily visible parts of portable items such as watch dials, lighter surfaces, and the front cover of compact cases, as well as to appropriate surfaces of indoor items that have a so-called decorative effect, not just portable items. This is a factor that not only increases the added value of the product but also stimulates the desire to purchase it. Naturally, this kind of decoration requires novelty, and especially these days, it is not only simple pictorial or geometric patterns, but also designs that change depending on the direction of the line of sight, or that give a sense of depth. Optical improvements have also been made.

On the other hand, so-called holography technology is becoming quite popular, and its decorative uses include stereoscopic video displays and geometrically colored displays that use geometrically patterned holograms such as diffraction grating images. The result is a decorative effect that cannot be achieved with other methods. By the way, decorations using holographic technology are based on interference fringe patterns formed on holograms, and as is well known, these interference fringe patterns are made by interfering at least two beams of light with high coherence, such as laser beams. The resulting material has an extremely fine structure on the order of the wavelength of light. Therefore, if such an interference fringe pattern is to be used to decorate general merchandise, a high-fidelity and low-cost hologram reproduction technique will be required. These demands are not limited to the mere application of holograms to decoration, but also require the establishment of hologram duplication technology for a wide variety of uses, such as when holograms are used as storage media.

Hologram duplication techniques that have been tried in the past can be roughly divided into so-called optical duplication, in which an original hologram is irradiated with a laser beam, and the resulting diffracted light is used to expose a new hologram sensitive material for duplication; There is physicochemical replication in which the fine structure on the original hologram is copied as a replica.
However, optical duplication requires complicated management and adjustment during duplication, and is not suitable for mass production. In addition, in the physicochemical replication that has been carried out so far, the interference fringes formed on the original hologram are transferred to the photoresist surface by photoetching, etc., and this is used as a master to obtain a copy, or the original itself is used as the master. In order to produce a hologram, a special dry plate with a photoresist layer is used, and the uneven image formed thereon is transferred to the substrate, such as aluminum, by an etching process to obtain a master for hologram reproduction.
However, even in these methods, the former has problems with the durability of the photoresist layer and is not suitable for mass reproduction, and the processing steps are complicated, and the fine irregularities of the interference fringes often deteriorate during this step. Furthermore, in the latter case, the sensitivity and resolution of the original hologram are inferior to those of commonly used silver salt photosensitive materials, and as a result, it is difficult to obtain good hologram copies.

Due to the above background, until now it has been extremely difficult to add interference fringe patterns such as hologram decoration to general products, and similar conventional decorations require physical or chemical methods such as etching. Geometric patterns have been used, and interference fringe patterns carrying optical information have rarely been applied. In addition, in purely decorative items such as pendants, the purpose of the decoration itself is the decoration itself, and since this can be quite costly, some items with interference fringes are offered on the market. It is extremely disadvantageous in terms of cost to use this as it is as a decoration for general products, and it has not been widely adopted.

In consideration of the above-mentioned circumstances, the present invention aims to provide a novel hologram duplication method that can be adopted in general products at an extremely low cost. At the point. Note that metal or hard resin-based materials are suitable as this hologram duplication material in order to maintain the unevenness of the interference fringes. Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a general holographic camera, which is used as a means for obtaining a hologram original used in the hologram duplication method of the present invention.
In FIG. 1, a beam from a laser light source 10 passes through a beam splitter 11, diverging lenses 12,
The object illumination light A and the reference light B are divided into the object illumination light A and the reference light B. Of the object illumination light A, the object light A' emitted by the object O interferes with the reference light B on the recording medium 15 such as a silver salt dry plate. As a result, the recording medium 15 is exposed to the interference fringes. When this is developed and fixed, interference fringes are recorded in the silver salt emulsion to form a hologram, but fine irregularities corresponding to the interference fringes are also generated on the surface of the silver salt emulsion. This hologram becomes one in which the fine irregularities generated on the surface of the silver salt emulsion are amplified by further performing a whitening process.

FIG. 2 is a conceptual diagram showing an example of the hologram duplication method of the present invention for making a duplication from the hologram original obtained as shown in FIG. 1, for example.
FIG. 2A is a sectional view of a hologram master plate H consisting of a silver salt emulsion 20 and its support 20a, and for convenience, interference fringes are schematically shown as S in an enlarged manner. In electroforming, it is necessary to make the hologram original plate H conductive at least on its surface, but since the surface of normal hologram materials does not have conductivity, the surface of the silver salt emulsion 20 of the hologram is In order to make it conductive, a metal layer 21 of silver, copper, etc. is deposited on the surface by electroless plating or vapor deposition. On the surface of this metal layer 21, a silver salt emulsion 2
The uneven pattern of interference fringes on the 0 surface is faithfully reproduced. Then, as shown in FIG. 2C, an electroforming process is performed in which a material 22 having a hardness suitable for a molding stamper is electrodeposited on the hologram original plate H which has been made conductive.
A Ni--Co alloy is suitable for this material 22, but Ni, Cu, etc. may also be used without any practical problems. Then, as shown in FIG. 2D, the electroformed metal is peeled off from the hologram master H to obtain a stamper 23. This stamper has a reverse pattern of fine interference fringes on the silver salt emulsion 20 of the hologram master H on the metal layer 2.
It is transcribed through 1. Thereafter, the interference fringes S of the hologram original H as shown in FIG. 2F are reproduced by retransferring them onto the surface of the thermoplastic resin 24 using the stamper 23 using the hot press method as shown in FIG. 2E, for example. A duplicate hologram 25 is obtained. In addition to the molding method using the stamper 23, an injection molding method is also possible, and a replica hologram made of metal can also be obtained by subjecting the stamper 23 to a re-electroforming process. In this way, a replica hologram made of metal or plastic is obtained, and this can be embedded or pasted as a decoration, for example, on the top cover surface of the compact case 30 shown in FIG. 3 (perspective view). FIG. 4 is a sectional view of the compact case cover 40 shown in FIG.
5. Fine irregularities are formed on the surface. Therefore, especially if the replica hologram 45 is made of plastic material, it may be coated with an optically homogeneous transparent material 55, as shown in FIG. 5, for the purpose of surface protection. Furthermore, if a reflective surface 65 is provided on the lower surface of the duplicate hologram as shown in FIG. 6, and the duplicate hologram is made transparent, it will receive the illumination from the reflective surface 65 as well as the reflection from the hologram surface, further increasing the decorative effect. .

Note that FIG. 7 shows an optical system for producing another hologram master. In FIG. 7, a laser light source 70
The light emitted from the photosensitive material 75 is split by a beam splitter 72, and the reflected light is diverged by a lens 73 and reaches a photosensitive material 75. On the other hand, the transmitted light is diverged by the lens 74 and reaches the photosensitive material 75 as well. Both luminous fluxes are
A diffraction grating hologram is created by recording interference fringes on a photosensitive material. A duplicate hologram that is a copy of this hologram is illuminated with any light (mainly white light) from any direction, so it exhibits a diverse color tone distribution and has subtle changes depending on the viewing direction, producing effects not found in conventional decorations. do. Moreover, FIG. 8 shows an optical system for producing not only such a pattern but also another hologram original. In FIG. 8, light emitted from a laser light source 80 is transmitted to a beam splitter 8.
Divided by 1. The reflected light is diverged by the lens 82 and illuminates the object O. The reflected light from object O is
An image of the object O is formed near the photosensitive material 85 by the lens 84.
Image O′. On the other hand, beam splitter 81
The transmitted light is diverged by the lens 83 and illuminates the photosensitive material 85. Both luminous fluxes are transmitted through the photosensitive material 85.
Interfering with white light to create a reproducible hologram. By producing a hologram master that can be reproduced with white light in this way, it is also possible to obtain a three-dimensional image of a specific image. However, 3D video displays require white illumination light to be radiated from a specific direction, so although it can be used in portable items, it is better to use it in indoor furniture and illuminate it from a designated area with the light of a dedicated lighting lamp. good.

Furthermore, when applying the replicated hologram according to the method of the present invention to the above-mentioned compact case front cover, it is of course possible to integrally mold the hologram at the same time as the front cover is molded.

As described above, in the hologram duplication method of the present invention, it is possible to manufacture a duplicate hologram from a hologram original very accurately and at low cost.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing an example of a holographic camera. FIG. 2 is a conceptual diagram illustrating the method of replicating a hologram of the present invention from a hologram original plate by electroforming. FIG. 3 is a perspective view showing an embodiment of a hologram decoration body in which a replicated hologram according to the method of the present invention is applied to a compact case. Fourth
The figure is a sectional view of the top cover in the embodiment of FIG. 3.
FIGS. 5 and 6 are cross-sectional views showing other embodiments of a hologram decoration body in which a replicated hologram according to the method of the present invention is applied to a compact case. FIGS. 7 and 8 are diagrams showing optical systems for producing other hologram masters, respectively. 10... Laser light source, 15... Recording medium, 2
0...Hologram original plate, 21...Metal layer, 22...
... Electroforming material, 23 ... Stamper, 24 ... Hologram replication material, 25 ... Replication hologram, 30
... Compact case, 55 ... Transparent substance, 65
...reflective surface.

Claims (1)

[Claims] 1. A hologram in which interference fringes are recorded on a photosensitive material is prepared as an original plate, and after the hologram surface is treated to become a conductor, metal is electrodeposited on the conductor to form a mold in the inverse shape of the hologram. How to replicate a hologram from a mold.