JPH01107288A - Color hologram - Google Patents

Abstract

PURPOSE:To enable the use of flexible substrates and to contrive the improvement in moisture resistance and the reduction of cost by combining a silver salt film and polymer film. CONSTITUTION:Green and blue hologram images are recorded on an N-vinyl carbazole hologram 1 on the flexible substrate 3 or the red hologram is recorded on the silver salt hologram 2 on the flexible substrate 5. Both holograms 1, 2 are joined by an adhesive agent layer 4. The luminous flux 21 from a white light source 20 is reflected and diffracted by the hologram 9 and is observed by an observer. The color hologram which is stable without being affected by environmental conditions such as moisture and temp., has flexibility and can be reduced in cost is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color hologram, and more particularly to a color hologram that can be illuminated with a white light source to obtain a clear reproduced image.

[Conventional technology]

One of the ultimate goals of three-dimensional image display technology using holograms is to display full-color three-dimensional images. If an ideal hologram recording material existed and a hologram could be photographed using a laser light source with wavelengths corresponding to the three primary colors of red, green, and blue, full-color display would be possible in principle. However, a photosensitive material that has uniform high sensitivity and high diffraction efficiency over the red, green, and blue wavelength regions has not yet been obtained.

Furthermore, because of the nature of displaying a three-dimensional image, it is desirable to be able to reproduce images using a white light source such as a halogen lamp instead of a laser light source.

With a transmission-type rainbow hologram, it is possible to create a hologram that displays a full-color 3D image using a single green light, but the disadvantage of this rainbow hologram is that the viewing area in the vertical direction is extremely narrow. .

Reflective volume holograms (Lippmann holograms) have a wide viewing area and have parallax information in both left and right and up and down directions.
The wavelength-selective nature of the hologram used allows it to be illuminated with white light to obtain a full-color three-dimensional image. The conventional photosensitive material that can be used for this type of hologram is a highly transparent, ultrafine-particle silver salt photosensitive material.

However, this silver halide photosensitive material has low sensitivity due to its low light absorption rate, requires long exposure times, and requires special technology for manufacturing and developing the photosensitive material, so the resulting hologram is extremely difficult to obtain. It has the disadvantage of being expensive, and it is difficult to increase the diffraction efficiency of the developed hologram due to absorption and scattering of blue light, making it difficult to increase the diffraction efficiency to 30% or more. Met.

As a full-color image display technology using Lippmann holograms, a currently feasible example is a method in which blue and green images are recorded on a dichromate gelatin hologram, while red images are recorded on a silver salt photosensitive material.
It is described in Optics, Vol. 25, pp. 4141-4145 (December 15, 1986 issue). FIG. 5 shows the structure of a display hologram that uses this technology and has sufficient durability for practical use. In the figure, a dichromate gelatin hologram 1 is formed on a glass substrate 13, while a silver salt hologram 2 is formed on a glass substrate 15. Both are bonded together via an adhesive layer 4. now,
When white light 21 from a white light source 20 enters the seratine dichromate hologram 1, a bright blue and green three-dimensional image is reproduced. Furthermore, since the dichromate seratine hologram has a high transmittance for red light, the red light enters the silver salt hologram 2 without being lost.
A red three-dimensional image with high diffraction efficiency can be obtained.

A full-color image produced by the combination of such blue, green, and red images is observed by the viewer 22'.

[Problem that the invention seeks to solve]

However, although the above-mentioned hologram can obtain a relatively good full-color three-dimensional image by combining currently available means, it has major drawbacks when various applications are considered.

That is, the biggest drawback of the conventional example is that in order to use the dichromate gelatin sensitive material, unless a thick glass plate is used as the substrate,
The problem is that practically sufficient moisture resistance cannot be obtained. Dichromate gelatin holograms are extremely sensitive to humidity, and if humidity is not completely blocked, the image may disappear completely in less than six months.

In the conventional example shown in FIG. 5, a glass plate 13.15 with a thickness of 1 mm or more is used to completely block humidity, and the adhesive 4 completely covers the periphery of the hologram sensitive material 1.2. There is a need.

Compared to such a structure of the conventional example, since the substrate is a glass plate, it is heavy (and expensive), and has disadvantages in that it is not flexible and easily breaks.

Since glass plates are easily broken, the locations where they can be used to display holograms are limited.

For example, when used on the cover of a book, it is impossible to use because there is a risk of it breaking during transportation or use.

If plastics such as acrylic plates are used instead of glass plates, the problem of easy breakage will be solved, but
Even a 1 mm thick acrylic plate could not be used as a substrate for a ceratine dichromate hologram because it would allow moisture to pass through.

Another drawback of the conventional example is that it is difficult to reduce the price. Conventionally, a glass plate is used as the substrate, so a method that has traditionally been suitable for inexpensive mass production, such as continuously coating a long film with recording material and winding it up, is used. It is not possible to use

As described above, the use of dichromate gelatin has been a major impediment to the practical use of holograms.

Therefore, the purpose of the present invention is to improve the color hologram, which conventionally required the use of a glass substrate to impart moisture resistance, and to make it stable and flexible, unaffected by environmental conditions such as humidity and temperature. An object of the present invention is to provide a color hologram that has the following properties and can be manufactured at a low price.

[Means and actions for solving the problem] The above purpose is
This is achieved by the following invention.

That is, the present invention is a color hologram characterized by having a silver salt film on which a reflective volume hologram of one or more colors is recorded and a polymer film on which a reflective volume hologram of one or more colors is recorded.

The color hologram of the present invention consists of one or more silver salt films and one or more polymer films.

The configuration of the color hologram of the present invention has the following aspects.

1) Red light (632,8 nm), green light (514 nm)
5 nm) were respectively recorded on a silver salt film, and blue light (4 nm) was recorded on a silver salt film.
88 nm) was recorded on a polymer film.

2) An embodiment in which red light is recorded on a silver salt film, and green light and blue light are each recorded on a polymer film.

3) Record red light and blue light respectively on silver halide film,
Embodiment in which green light is recorded on a polymer film.

4) An embodiment in which red light and green light are recorded on a silver salt film, and blue light is recorded on a polymer layer.

5) An embodiment in which red light was recorded on a silver salt film, and blue light and green light were recorded on a polymer film.

6) An embodiment in which red light and blue light were recorded on a silver salt film, and green light was recorded on a polymer film.

Examples include those with a two-layer structure such as.

Among the above embodiments, particularly preferred is the three-layer structure 2)
In the case of a two-layer structure, this is the embodiment 5).

The reason for this is that the hologram manufacturing process can be shortened by simultaneously exposing the same recording material to blue and green light and performing the same development process.

The advantage of having a three-layer structure is that the conditions for each layer recorded with red light, green light, and blue light can be set so that each layer has high diffraction efficiency and low noise when recording in each color. It is possible to set processing conditions for each layer, and it is also possible to successfully correct the difference between the wavelength of the reproduction light suitable for displaying the image and the wavelength of the recording light used when creating the hologram. That's true.

In the present invention, various combinations of the laminated color holograms, such as silver salt film-silver salt film-polymer film, silver salt film-polymer film-polymer film, etc., can be selected depending on the intended use.
For example, when laminating films in a silver salt film-polymer film-polymer film combination, a pressure-sensitive adhesive or an adhesive layer is interposed between the films to further secure the films. A protective film is formed by laminating a 5-200 μm film that is transparent to the extent that it does not interfere with the color properties and has no particular absorption in the wavelength range of 400-800 nm during color display on the polymer film surface that forms the outer surface. You can also do that. It is common practice to use an adhesive or a pressure-sensitive adhesive layer at the interface between the transparent film and the polymer film, and there is no hindrance to its use as long as it does not adversely affect the hologram image.

Furthermore, it is adhered to the polymer film surface that forms the outer surface, the transparent film surface, the back surface of the silver halide film, etc.

By providing an adhesive layer, a transferable full-color display hologram sheet can be obtained.

The silver salt hologram that can be used in the present invention is, for example, commercially available from Agfergewald or Eastman Kodak, and uses a silver salt photosensitive film and a laser that corresponds to a desired color with a predetermined optical system. It is obtained by exposing it to light, followed by prescribed development and bleaching.

The polymer film that can be used in the present invention can be prepared by a known method (K, Ma
t sumo to other 5PIEVo1.600P
regression H.

1 graphic A, plecations (
1985) P9) It can be obtained by laminating a holographically recorded polymer thin film layer on a transparent film by a method such as transfer, or by coating the transparent film and exposing and developing it.

The thickness of the polymer film used in the present invention is 4 to 50
The range is preferably 6 to 30 μm. When the film thickness exceeds 50 μm, the film tends to become cloudy and crack (which causes harmful phenomena on the surface). When the film thickness is less than 4 μm, the wavelength selection characteristics of reflected light become weak, resulting in bright colors. Display becomes impossible, and the diffraction efficiency decreases so that the image cannot be seen.

〔Example〕

Hereinafter, the present invention will be specifically explained using Examples.

Example 1 A Lippmann hologram with respect to light of 633 nm was recorded using a He-Ne laser on a silver salt-based sensitive film for Lippmann holograms, HOLOTe s t8E75HD film manufactured by Agfagewald.

The recorded film was developed and bleached according to the processing procedure shown in Table 1, and this was used as a silver salt film for red reproduction.

Next, 10 parts by weight of polyvinylcarbazole, 0.1 parts by weight of tetraiodide, and 0.1 parts by weight of methane dissolved in 100 parts by weight of monochlorobenzene were applied onto a transparent glass substrate using a spinner, dried at room temperature for several hours, and the thickness was It was set to 12 μm. to this,
458nm and 514.5n with Ar-ion laser
Lippmann holograms for light of m were multiplexed recorded.

The illumination position is the same as in the case of silver halide film.

The recorded film was immersed in xylene at 3°0°C for 1 minute, then immersed in n-hexane at 40°C for 30 seconds and dried at room temperature to obtain a polymer film for green and blue reproduction.

When the above two films were adhered together using adhesive and observed by irradiating white light with a halogen lamp, we found that:
A clear full-color reproduced image was obtained.

The spectral profile is shown by the solid line in FIG.

The peak wavelengths are 638, 531°479nm, respectively.
Met.

The configuration of the first embodiment is shown in FIG. Blue and green hologram images are recorded on the N-vinylcarbazole hologram 1 on the flexible substrate 3, and a red hologram is recorded on the silver salt hologram 2 on the flexible substrate 5. Both are bonded by an adhesive layer 4. A light beam 21 from a white light source 20 is reflected and diffracted by a hologram 9 and observed by an observer.

Example 2 A silver salt film for red color reproduction was produced by the same method as in Example 1.

Next, in the same manner as in Example 1, a polyvinyl carbazole film was laminated on two transparent glass substrates.
458 nm and 514 nm respectively with Ar ion laser. A Lippmann hologram was recorded for light of jnm. 458 n rn light has a thickness of 5
After recording in μm, the sample was immersed in Quinton at 30°C for 1 minute, then immersed in n-hexane at 44°C for 30 seconds, and dried at room temperature. This was used as a polymer film for blue reproduction.

For the 514.5 nm light, after recording with a thickness of 7 μm, it was immersed in xylene at 30° C. for 1 minute, then immersed in n-hexane at 35° C. for 30 seconds, and dried at room temperature. This was used as a polymer film for green reproduction.

When the above three films were closely attached and observed by irradiating white light with a halogen lamp, a clear full-color reproduced image was obtained. The spectral profile is shown by the broken line in FIG.

The peak of each wavelength is 637°549.
It was 452 nm.

FIG. 2 shows the blue light and green light Bl of Example 1.

The blue light and the green light B2°G2 of Example 2 each have more desirable center wavelengths than G1, and as a result, the color reproduction range as a full-color image is expanded.

FIG. 3 shows part of a method for continuously manufacturing holograms of Example 2. Flexible substrate 3.3'
, 5 are pressed between rollers 12.13 via an adhesive (not shown) to form hologram 1.
It becomes 0.

FIG. 4 is a diagram showing a process of mass producing holograms from the elongated holograms shown in FIG. 3.

After the long hologram 10 is positioned, the cutter 11
The hologram 9 is obtained by cutting out the hologram 9.

In this way, it is possible to obtain a mass-produced tube (hologram) at low cost.A hologram obtained by mass production as shown in FIG. A fringe will definitely occur.The N used in the present invention
- Since polyvinyl carbazole holograms have high moisture resistance, there is no problem even if the cut surfaces are exposed, and holograms can be obtained at low cost and with good mass production.

〔Effect of the invention〕

As described above, in the present invention, instead of conventional dichromate gelatin, N
- By using polyvinylcarbazole, a full-color hologram with improved moisture resistance was obtained. Furthermore, since it has become possible to use a flexible substrate, it was previously impossible to use full-color Lippmann holograms.

It has become possible to use it in various application fields.

For example, it can be applied to book covers, souvenir tickets, telephone cards, on the outside of tablets, on cylindrical appliances, as flooring materials, etc.

In the embodiments of the present invention, only full-color images of blue, green, and red are shown, but if a two-color configuration of a red image and a blue-green image is also subjected to design processing, an effective display effect can be obtained. be able to.

Furthermore, in the present invention, by combining a silver salt film and a polymer film, it was possible to realize a full-color hologram that combines the advantages of both. Thus, for blue and green light display, polymers with transparency and high diffraction efficiency can be used, and for red light, silver halide films can be used for Lippmann hologram recording. , high sensitivity and diffraction efficiency can be achieved. For mass production, a high-output argon laser with a total output of 8W, for example, can be used for blue and green, while a helium-neon laser with an output of 20mW, for example, can be used for red light, so the sensitivity to red light is low. is particularly necessary, and there is a great advantage in using a silver salt sensitive material for this purpose.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of a hologram according to the first embodiment of the present invention, Fig. 2 is a diagram showing the spectral reflection characteristics of Examples 1 and 2 of the present invention, and Fig. 3 is a diagram showing the hologram configuration of the first embodiment of the present invention. FIG. 4 is a diagram showing an example of the manufacturing process of the hologram of the present invention. FIG. 5 is a diagram showing a conventional color hologram made of dichromate gelatin and silver salt hologram. It is. 1.1'... N-polyvinylcarbazole hologram layer 2... Silver salt hologram layer 3.3'... Flexible transparent substrate 4... Adhesive 5... ...Flexible substrate 9 ...... Combined hologram 11 ...
... Cutter 12.13 ... Roller 13.15 ... Glass substrate 20 ... White light source 21 ... White light 22 ... Observation person

Claims (2)

[Claims] (1) A color hologram comprising a silver salt film on which a reflective volume hologram of one or more colors is recorded and a polymer film on which a reflective volume hologram of one or more colors is recorded. (2) The color hologram according to claim 1, wherein the polymer film is mainly composed of a vinyl carbazole polymer.