JPS63287989A - Hologram - Google Patents

Abstract

PURPOSE:To obtain a hologram which is easy to handle and to provide a good reconstructed image free from blurring by providing a colored filter having a spectral transmission characteristic integrally with a hologram. CONSTITUTION:A hologram grating 101 is formed on a transparent substrate 102 and a multi-layered film coating 91 having the spectral transmission characteristic is disposed on the opposite side. The coating 91 allows 100% transmission of light in a wavelength region having a center at, for example, 530nm and 100% reflection of red light of <=460nm and >=600nm. A luminous flux 2 of a light source 1 passes the filter 91, is reflected and diffracted by the hologram grating 101 and again transmits the filter 91 to form the three- dimensional reconstructed image 6 and, therefore, the formation of the monochromatic image is sufficiently executed. The blurring is thus prevented and the good image is obtd. Since the hologram and the filter are integrally formed, the handling is extremely facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hologram that displays a three-dimensional image in the visible wavelength range, and particularly relates to a reflective volume phase hologram.

(Prior Art) In recent years, with the development of hologram technology that allows stereoscopic images to be obtained even when illuminated with a white light source, holograms for displays have come to be used in a wide variety of applications.

Among these white light reproduction holograms, a reflection hologram (Lippmann hologram) uses a volume phase diffraction grating.
is considered to have high market value because it can obtain three-dimensional images with high resolution and precise impressions, and reproduced images with not only single colors such as green, blue, and red, but also golden metallic luster. It is evaluated.

By using this Lippmann hologram to limit the wavelength range used to a narrow wavelength width, it is possible to
Techniques are known for creating images that do not cause blurring at positions that are more than 0.001 cm or deeper than 1 m.

The conventional technique will be explained using FIG.

Immediately after the white light source 1, a color filter 9 having relatively narrow spectral transmittance characteristics is arranged.

After the white light 2 from the white light source passes through the filter 9, it becomes relatively monochromatic light, for example, a green light flux,
This light beam 2 illuminates the hologram.

The hologram is composed of a hologram grating 101 formed on a transparent substrate 102, an adhesive layer 103, and a cover plate 104. The hologram illumination light flux 2 is reflected and diffracted by the hologram grating 101 to become a light flux 3, which is observed by an observer 4 to obtain a three-dimensional image 6.

Here, the three-dimensional image 6 has the property that when the hologram illumination light 2 contains light of various wavelengths, a change in the diffraction direction caused by the wavelength difference causes a large blur at a position far away from the hologram grating 101. have. In the conventional example, the purpose of reducing blur even when the depth of the reproduced image 6 becomes deep is achieved by providing the filter 9 with a wavelength transmission characteristic of an appropriate width.

However, in the two conventional examples, the hologram itself and the color filter 9 are completely separated, resulting in various inconveniences. First of all, the first drawback is managing, moving, and
It is inconvenient to handle exhibitions, etc. Hologram works for display are created based on strict intentions from the beginning, such as the depth, color tone, and content (theme) of the reproduced image. Nowadays, when a work is created with the intention of expressing deep depth through a green filter, if the filter is lost and the light is illuminated with white light, or if the artist accidentally lights it through a red filter, the artist may Not only does this not reflect the intended purpose of the work, but the reproduced image becomes severely blurred and distorted, which completely loses the value of the work. For this reason, it was necessary to manage each individual work and the color filter at the same time when storing the work or transporting it to exhibit at another location. This is extremely troublesome to handle, and is one of the factors that creates a situation in which only experts can handle holograms.

A second drawback of the conventional example is that the filter is disposed near the light source and is therefore susceptible to deterioration due to the heat of the light source. As is clearer than the conventional example shown in Figure 6, since the conventional filter 9 is disposed immediately after the light source, it is greatly affected by the heat of the light source, causing the filter itself to undergo changes in color tone and yellowing of the material. In addition, problems such as an increase in scattered light due to crystallization have arisen.

A first object of the present invention is to provide a hologram means that allows even a person unfamiliar with holograms to reliably handle color filters for illumination, which have conventionally been inconvenient to handle.

A second object of the present invention is to provide a hologram that does not suffer from the conventional problem of filter deterioration due to the influence of heat from a light source.

Furthermore, another object of the present invention is to compensate for variations in color tone between individual holograms or production lots to a practically sufficient extent when mass producing reflective holograms of the same color tone, thereby achieving a high yield and uniform quality. The goal is to provide a hologram of

(Means for solving problems) The objects of the present invention are achieved by the following invention.

That is, one aspect of the present invention is a hologram having a potted hologram diffraction grating that reflects and diffracts a light beam from a visible light source to display an image, which is characterized by being equipped with an optical member having spectral transmittance characteristics.

(Function) By disposing a filter in the optical path from the illumination light source to the hologram grating and configuring the filter integrally with the hologram itself, various problems of the prior art can be solved at once.

Preferred Embodiments The present invention will now be described in more detail with reference to the accompanying drawings, which schematically show preferred embodiments of the invention.

A first embodiment of the present invention will be described using FIG. A light beam 2 from a white light source 1 illuminates the hologram. The hologram grating 101 is formed on a transparent substrate 102, and a multilayer coating 91 is formed on the opposite surface of the transparent substrate 102.
is installed.

Here, the multilayer coating 91 has a wavelength of 53, for example.
Approximately 100 wavelengths of light with a certain width centered around 0 nm
It has a characteristic that 100% of other color light, such as blue light with a wavelength of 4600 nm or less and red light with a wavelength of 600 nm or more, is reflected. As a result, the hologram grating 101 is first illuminated with the light that has passed through this filter 91, and the reflected and diffracted light beam 3 passes through this filter 91 again, so that sufficient monochromation is achieved and the depth of the reproduced image 6 is This means that blurring of the image can be sufficiently prevented even when the distance is deep. Note that it is desirable that the filter 91 be formed before the hologram photosensitive material is applied to the substrate 102. To apply a hard coating with excellent environmental resistance, it is necessary to heat the substrate sufficiently.

Further, as a secondary effect of this coating 91, there is an effect of preventing ghosts during hologram printing exposure. for example,
When exposure is performed with monochromatic light of wavelength 514.5n@ from an argon laser, this coating 91 acts as an antireflection film, and as a result, ghosts and interference fringes occurring in the hologram reproduced image 6 are prevented.

The cover plate 104, which is transparent, opaque, or wavelength-selective, is attached via an adhesive layer 103.

As described above, since the coating 91 is separated from the light source 1, it is not affected by the heat of the light source and does not deteriorate.A second embodiment of the present invention is shown in FIG. In this embodiment, the substrate 92 is a colored glass, a colored plastic plate, or a colored plastic film. By coloring the substrate 92, unnecessary wavelength light in the illumination light beam 2 and the diffracted light beam 3 is absorbed, and blurring of the reproduced image 6 is prevented.

A third embodiment of the present invention is shown in FIG.
After passing through the hologram grating 101 formed on the substrate 104, the zero-reflected and diffracted light beam 3 passes through the adhesive layer 103 and the colored cover plate 93 to become a diffracted light beam 3. In this embodiment, after the hologram grating 101 is completed and the color of the reproduced image is appreciated, the colored cover 101 is
3, new effects that could not be obtained in the first and second embodiments can be obtained. This means that it is possible to fine-tune the color tone of the reproduced image 6. For example, if a large amount of gold products with a certain brightness and tone are required, colored cover plates with several colors and transmittances can be used. 93. If the reproduced image obtained now has a strong reddish tinge, use a slightly blue colored cover 93, and conversely, if the reproduced image has a strong bluish tinge, use a slightly blue colored cover 93. Combine the colored cover 93. In addition, when the color tone is as desired, the brightness is often too bright, and in this case, a colored cover plate 93, which absorbs all wavelengths almost uniformly and corresponds to a neutral density filter for photography, is combined. .

FIG. 4 is a schematic diagram of a state in which a large number of holograms according to the present invention are arranged. Individual holograms 99, . 992,99
□, 994 playback images 6, . 6. ．． 6. ．． 64- has its color tone and brightness finely adjusted by a colored cover plate, so no matter how many holograms are arranged, there will be no difference in color between adjacent holograms, making it possible to create a very large hologram display. Realized.

In the first embodiment as well, color tone adjustment can be performed in the same manner as in this embodiment. In the hologram shown in Figure 1, by attaching a colored film as 91 in the final step,
After all, you can make fine adjustments to the color tone.

A fourth embodiment of the invention is shown in FIG. A colored protective layer 94 is formed on the hologram grating 101.

This protective layer 94 is formed, for example, by mixing a coloring agent into an ultraviolet curable adhesive and curing it with ultraviolet rays, or by similarly mixing a coloring agent into a thermosetting adhesive and heating the mixture.

In this embodiment as well, the color tone can be adjusted, and it is also possible to provide a transparent protective plate or a protective film thereon.

(Effects) As described above, in the present invention, the colored filter, which was conventionally placed on the light source side of hologram illumination, is integrated with the hologram, making it convenient to handle and allowing reproduction images with deep depth and no blur to be produced at any time. It has become possible to realize this.

In addition, the lid makes it possible to prevent deterioration due to heat of the light source of the color filter that is conveniently used at this time.

Furthermore, as a side effect, since the reproduced image of each hologram can be finely adjusted, quality can be made uniform during mass production, which is a great advantage.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of the invention, FIG. 2 is a sectional view showing a second embodiment of the invention, and FIG. 3 is a sectional view showing a third embodiment of the invention. , FIG. 4 is a perspective view showing an embodiment in which a large number of third embodiments of the present invention are arranged, FIG. 5 is a sectional view showing embodiment #44 of the present invention, and FIG. 6 is a conventional example. FIG. 1: Hologram illumination light source 2: Illumination light flux 3: Diffracted light flux 4: Observer 6: Three-dimensional reproduced image 91: Colored filter 92z Colored substrate 93: 41 color cover plate 94: Colored protective layer 99+, 99z, 99*: Arranged Hologram 101: Hologram grating 102: Transparent substrate 103: Adhesive layer 104: Cover plate Patent applicant: Canon Co., Ltd. - Toji Ryo

Claims (1)

[Claims] A hologram having a volume hologram diffraction grating that displays an image by reflecting and diffracting a light beam from a visible light source, the hologram comprising an optical member having spectral transmittance characteristics.