JPH0361984A - Reconstruction device for fourier hologram - Google Patents

Abstract

PURPOSE:To improve a projection screen so as to allow the observation of a bright reconstructed image with less light losses by using the end faces of bundled optical fibers as the screen. CONSTITUTION:A hologram is recorded by a Fourier type on this Fourier hologram recording medium 2. The hologram is irradiated with the laser beam 1 from a laser beam generator 10. The reconstruction light 3 from the Fourier hologram recording medium 2 is projected to one end face of the projection screen 4 to form the reconstructed image. The end faces of the bundled optical fibers are used as the projection screen 4. The reconstructed image is, therefore, eventually formed on the end faces of the optical fiber bundle. The observation of the brighter reconstructed image than heretofore is possible in this way and the reconstruction of the image to a larger area is possible.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to the field of information recording and display using holography, and particularly relates to an improvement of an apparatus for reproducing images from Fourier holograms.

[Conventional technology]

Holograms recorded in Fourier format generally have a diameter of 1
Since it can be made to the size of a crystal, a reconstructed image can be easily obtained by direct irradiation with a laser beam from a He-Ne laser or the like having a diameter of about III11. To explain using a diagram, as shown in FIG. 2, a hologram recorded in a Fourier format on a Fourier hologram recording medium 2 is irradiated with a laser beam 1 from a laser beam generator 10, and the reproduction light 3 is Project it onto a screen and form an image. As this projection screen, a plate made of a translucent light-scattering material, such as a frosted glass plate 7, has conventionally been used. Since the light from the image formed on the ground glass plate 7 becomes scattered light 8, this image can be observed from the rear of the ground glass plate 7 (from the right side in the figure).

[Problems to be Solved by the Invention] However, if a plate made of a translucent light scattering material such as the frosted glass plate 7 is used as a projection screen as in the past, the reproduced image will not be displayed as shown in FIG. The light from the viewing direction becomes scattered light 8 that is scattered around, and a high proportion of the light is scattered in directions other than the observation direction 6. Therefore, when observing from the observation direction 6 with human eyes, there is a problem that the brightness of the image is impaired. SUMMARY OF THE INVENTION An object of the present invention is to provide a Fourier hologram reproducing device that is improved so that a bright reproduced image can be obtained. [Means for Solving the Problems] In order to achieve the above object, the present invention provides a Fourier hologram recording medium in which a hologram is recorded in a Fourier format, and a laser beam generator that generates a laser beam to irradiate the hologram. and a projection screen onto which the reproduction light from the recording medium is projected, characterized in that the end face of a bundle of optical fibers is used as the projection screen.

[For production]

When a hologram recorded in a Fourier format on a Fourier hologram recording medium is irradiated with a laser beam and reproduction light from the recording medium is projected onto a projection screen, a reproduced image is formed on the screen. The end face of a bundle of optical fibers is used as this projection screen, and therefore the reproduced image is formed on the end face of this bundle of optical fibers. As a result, this reconstructed image can be observed from the other end surface of the optical fiber bundle. In this case, the light emitted from the other end face of the optical fiber bundle is transmitted light that has passed through each optical fiber of the optical fiber bundle. Therefore, the direction of this emitted light is restricted as it has passed through each optical fiber, and it does not become scattered light that is scattered around like when a conventional frosted glass plate is used as a screen. If the observation direction is set in the same direction as the direction of the light emitted from the other end face of the fiber bundle, a bright reproduced image with less light loss can be observed.

【Example】

Next, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, a hologram is recorded on a Fourier hologram recording medium 2 in a Fourier format,
This hologram is irradiated with a laser beam 1 from a laser beam generator (eg, a He--Ne laser oscillator) 10 . The reproduction light 3 from the Fourier hologram recording medium 2 is projected onto one end surface (the left end surface in the figure) of the optical fiber plate 4 to form a reproduction image. The light from this reconstructed image passes through each optical fiber of the optical fiber plate 4 and is emitted from the other end surface (the right side in the figure). Since this emitted light is the transmitted light 5 of the optical fiber plate 4, It does not spread that much, and its direction is limited to a narrow angle centered on the direction of each optical fiber.The direction that coincides with the direction of each optical fiber of this optical fiber plate 4 is defined as an observation direction 6, and the direction is limited to a narrow angle centered on the direction of each optical fiber. Observe the reconstructed image. In this case, the direction of the light from the reconstructed image formed on the left end surface of the optical fiber plate 4 is restricted by passing through each optical fiber of the optical fiber plate 4. Therefore, the emitted light is collected in the observation direction 6, and the ratio of scattering in other directions is reduced, so that it can be observed as a bright reconstructed image from the observation direction 6. , an optical fiber plate 4 in which a large number of optical fibers are bundled and sliced in a direction transverse to them.
However, not only such a thin optical fiber bundle but also a long optical fiber bundle can be used. By guiding a long optical fiber bundle to a long distance or bending it in an arbitrary direction, it becomes possible to transfer a reconstructed image over a long distance or in an arbitrary direction. In addition, since both ends of the optical fiber bundle can have any shape, it is also possible to configure a curved screen by setting the end surface on the side where the reconstructed image is formed as a curved surface, or to enlarge or reduce the reconstructed image. It is. The area of the end face of the optical fiber bundle, the thickness of each optical fiber constituting the optical fiber bundle, the arrangement density, etc. can be arbitrarily determined depending on the area, resolution, etc. of the reproduced image. [Effects of the Invention] According to the Fourier hologram reproduction device of the present invention, a reproduced image brighter than before can be observed. Therefore, the output of the laser beam generator for reproduction can be reduced, and even if the reproduced image is formed over a large area, the brightness will not be insufficient, making it possible to reproduce the image over a large area. Become.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention, and FIG. 2 is a schematic diagram of a conventional example. DESCRIPTION OF SYMBOLS 1... Laser beam, 2... Fourier hologram recording medium, 3... Reproduction light, 4... Optical fiber plate, 5... Transmitted light, 6... Observation direction, 7... Ground glass Plate, 8...Scattered light, 10...Laser beam generator.

Claims (1)

[Claims] (1) A Fourier hologram recording medium having a Fourier hologram recorded thereon, a laser beam generator that generates a laser beam to irradiate the hologram, and a projection screen onto which reproduction light from the recording medium is projected. A Fourier hologram reproducing apparatus, characterized in that the projection screen is an end face of a bundle of optical fibers.