JPH036882Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a white reflected light reproduction type hologram.

There are two methods for reproducing a hologram image: one using transmitted light and one using reflected light.
From a manufacturing principle, they are the same in that interference fringes are recorded on a photosensitive material using a laser, and the difference in image reproduction method is simply a difference in the optical system used during recording.

However, in terms of the practicality of holograms, image reproduction using reflected light has the advantage that the human visual system can more easily see three-dimensional images, just as with general two-dimensional photography. .

Reflected light reproduction holograms include white light reproduction holograms using dichromate gelatin and relief holograms using the principle of rainbow holograms. These holograms are characterized by the possibility of white light reproduction under electric lamp light or sunlight.

However, the above two types of reflected light reproduction type holograms have the following problems.

In other words, dichromate holograms are sensitive to humidity and the image may disappear, so the surface is protected with a glass plate, but when viewing a three-dimensional image under a point light source, the light source reflects off the glass plate and enters the field of view. , it can be dazzling.

In addition, for relief holograms, it is necessary to improve diffraction efficiency by forming a thin film layer of highly reflective metal by vapor deposition or sputtering on the press surface, which has been transferred from the master mold to the plastic surface as uneven interference fringes. . Since the portion where the interference fringes are not recorded as unevenness is a flat surface, the light source may enter the field of view directly, creating a sense of glare, similar to the surface of the protective glass described above.

The present invention prevents this phenomenon and makes it possible to comfortably view stereoscopic images.

To explain with reference to the drawings, the hologram 1 of the present invention, as shown in FIG. It is characterized by

In the hologram of the present invention, the principle that the light source does not appear reflected can be explained as follows.

A circularly polarizing plate can be easily formed by combining a linearly polarizing plate and a quarter wavelength plate. As schematically shown in FIG. 2, the light from the light source 11 becomes linearly polarized light by the linear polarizing plate 12, and when this enters the quarter-wave plate 13, two components in the direction of the optical elastic axis are generated.
When the light is separated into Io and Ie and travels, the phase of the two components is shifted by 90 degrees, and the phase of the two components is shifted by 180 degrees as a whole.As a result, the reflected light becomes linearly polarized light rotated by 90 degrees with respect to the incident light. No light is emitted from the plate 12. In this way, reflected light from the mirror surface, that is, the protective glass surface, or the flat part of the hologram will not enter the field of view, and glare can be prevented.

On the other hand, if the reflecting surface is not a mirror surface and interference fringes are recorded, and the phase is already shifted by an angle △ at the time of reflection, the reflected light will be reflected on the quarter-wave plate and even if the phase shifts by an additional 90 degrees, The total deviation is (90+△)°, and the light is not linearly polarized, but elliptically polarized. Therefore, light containing three-dimensional information due to interference fringes is emitted from the linearly polarizing plate on the front side. Therefore, there is no problem in forming a holographic image.

The specific structure of the hologram of the present invention is, in the case of a dichromate hologram, as shown in FIG.
Paste. For pasting, it is preferable to use an adhesive, a transparent double-sided adhesive film, or an ultraviolet curing adhesive. For double-sided adhesive film,
It must be unstretched or biaxially stretched at the same stretching ratio, in other words, it must have optical isotropy. 4 above the dichromate photosensitive layer 2A is an ultraviolet curing resin, 5' below is a rear glass,
6 is a shield material at the end.

An example of this is a 30cm square dichromate dry plate (glass substrate thickness 5mm, photosensitive layer thickness 100μ).
Using the contact exposure method, a three-dimensional object is photographed with an argon laser and developed. The gelatin layer on the outer periphery of the dry plate was removed in a width of 5 mm, a cover glass (thickness 3 mm) was closely bonded using an ultraviolet curable resin adhesive (WR Grace), and a circularly polarizing plate (Polaroid, HNCP) was placed on top of the cover glass (3 mm thick). -37) with the same adhesive.

When this hologram is reproduced using a white light source spotlight, the reflected light from the cover glass is reduced by about 80% compared to one without a circularly polarizing plate, making it possible to further advance wide-field reproduction.

In the case of a relief hologram, as shown in FIG. 3, an acrylic resin layer is coated on a base film 7 made of, for example, polyethylene terephthalate, and uneven interference fringes are recorded on the surface of the relief hologram 2B by pressing or transferring. A circularly polarizing plate 3 is pasted onto the reflective relief hologram by vapor-depositing it with an ultraviolet curing adhesive 4.

This hologram suppresses reflections on flat surfaces even under sunlight, producing a three-dimensional image with sufficient contrast.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of the hologram of the present invention. FIG. 2 is a schematic diagram for explaining the principle of the present invention. FIG. 3 is a sectional view similar to FIG. 1, showing another example of the hologram of the present invention. 1, 1A, 1B...Hologram, 2, 2A, 2
B...Photosensitive layer, 3...Circularly polarizing plate.

Claims (1)

[Scope of utility model registration request] A hologram 1 characterized in that a circularly polarizing plate 3 is provided on the incident light surface side of a photosensitive layer 2 of a white reflected light reproduction type hologram.