JPS6015946B2 - Hologram observation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hologram reproduction method that allows a wide observable area to be obtained.

Broadly speaking, hologram reproduction methods can be divided into two: methods in which the hologram is illuminated with reproduction light and an observer looks directly into the hologram to observe the reproduced virtual image, and methods in which a stereoscopic screen is placed near the reproduced real image and the real image is Method 2 of observing
That's right.

Note that the term "real image" includes an image made into a real image by a virtual image lens means. The hologram observation method of the present invention relates to a method similar to the latter method.

How to use a stereoscopic screen is AppliedO
ptics, Vo17, No. 4April l96
8PP627-631.

In this method, a real image reproduced from a hologram is projected onto a directional screen, and this projected image is observed. However, this method of using a directional screen has the drawback that the observable area of the projected image is limited to the size of the hologram. As a method to solve this drawback, for example, a method of using a stereoscopic screen shown in US Pat. No. 2,351,033 and expanding the observable area only in the direction perpendicular to the parallax direction can be considered.

However, with this method, the observable area is expanded only in the direction perpendicular to the inkstone difference direction, and cannot be expanded in the parallax direction. This is because if the screen is made to have diffusive properties even in the parallax direction, the parallax information will overlap, making it impossible to observe a three-dimensional image. An object of the present invention is to provide a hologram observation method which eliminates the above-mentioned drawbacks, and which allows at least the afterimage effect of the eye to be observed in a conjugate image of a hologram in a plane, in a direction perpendicular to the plane, or in a combination of the two. This goal is achieved by moving the object as fast as possible.

The method of the present invention will be explained below using the accompanying drawings.

1 is a hologram. This hologram is illuminated by the reproduction light and is moving in the inner plane formed by the frame 2 or in a direction perpendicular to this plane. 3 is a big mouth rule screen.

In the picture, a large mouth is shown. Here, the directional screen refers to a screen that focuses light from one point on a single point. A hologram is placed near the front focal plane of this large-mouth lens. 4 is an image of the frame 2 formed by the large aperture lens 3; 5 is the image of the large aperture lens 3;
This is an image of hologram 1 formed by.

This hologram image 5 is moving in the inner plane of the image 4 of the frame 2 or in the vertical direction. Now, if the observer's eyes are placed within the range in which the hologram image 5 of the image 4 in the frame 2 moves, there is a possibility that the observer will receive light from the hologram 1.

Within this range, the viewer can observe the reproduced image almost in the vicinity of the screen. The observable castle of this reconstructed image is enlarged in the inner plane of the frame image and in the direction perpendicular to this inner plane. In the explanation of FIG. 1, the hologram 1 is actually moved, but it is sufficient that the hologram image 5 is actually moved, and this can be achieved by using, for example, a vibrating mirror.

That is, it is sufficient to move the conjugate image of the hologram with respect to the large-mouth lens screen and observe the reconstructed hologram image within the moving range. The method of the invention is particularly useful for reconstructing Fourier transform holograms.

This is because the Fourier transform hologram has a property that the reproduction position of the reproduced image remains constant even if the hologram is moved, so the image does not move due to the movement of the hologram. An example of a method for creating this Fourier transform hologram will be explained below using FIG. 2.

6 is an object.

This object 6 is illuminated by coherent light. 7 is a Fourier transform lens.

8 is a hologram recording body, and 9 is a reference wavefront.

A hologram created with this arrangement is called a Fourier transform hologram, and has the properties described above.

Note that this Fourier transform hologram can be created without using a lens by placing a reference wave point light source near the object other than by the method shown in FIG. FIG. 3 shows an example in which the reproduction method of the present invention is applied to such a Fourier transform hologram reproduction method.

This Fourier transform hologram is then cut into strips to reduce information. This is a strip-shaped Fourier transform hologram.

This hologram 10 is moving in a direction in which information is reduced, as indicated by an arrow. 11 is an inverse Fourier transform lens.

This lens 11 forms a reproduced real image 12 almost in the vicinity of the large lens screen 3. 13 Hashins 1
This is a hologram image formed by 1 and 3.

Therefore, by bringing the eyes to position 13, the reconstructed image 12 can be observed for a moment. Since the image 13 moves in the direction of the arrow, if a hologram image is formed at a position other than the position indicated by the diagonal line 13, the reconstructed image 12 becomes observable at the part where the image is formed, and the observable area is indicated by the dotted line. It has been expanded accordingly.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the hologram observation method of the present invention, FIG. 2 is a diagram explaining a Fourier transform hologram, and FIG. 3 is a diagram explaining the case where the method of the present invention is applied to the Fourier transform hologram observation method. be. Group's illustrations Figure 2 Figure 3

Claims (1)

[Claims] 1. Illuminating the Fourier transform hologram with reproduction light, placing a large-diameter lens screen at or near the position where the reproduction image is formed, and transmitting the conjugate image of the hologram formed by the large-diameter lens screen to the large-diameter lens screen. A method for observing a hologram, comprising: moving the hologram with respect to the hologram, and observing the reconstructed image within a range in which a conjugate image of the hologram moves.