A real-time color holography system is developed using a high-resolution reflective liquid-crystal display (LCD) panel
that consists of a 1400x1050 array of square pixels with width of 10.4 micron. Red, green and blue images with high
resolution are reconstructed from the holography system with a red laser diode (LD), a green laser and a blue lightemitting
diode (LED) as the reference light. The reconstructed color image with high resolution can clearly be observed
under the room light. Directly viewable color images with both eyes or images in the wide visual field are reproduced
using the 3-channel LCD modulator. The viewing-zone angle or the visual-field angle of the 3-D display system can be
expanded up to about 9 degrees using three LCD panels. Fringe patterns for a practical object are also recorded by a
high-resolution CMOS sensor, and a moving image of the object is reproduced from the fringe patterns by the
developed holographic display system.
A method of hologram bandwidth reduction and a method of size change of a 3D image are described. Spatial
frequency bands of a Fourier-transform hologram (FTH) are superimposed for reduction of the bandwidth and for
production of a continuous periodic FTH. Resolution of the image is improved by the superimposing method. The
second hologram for reconstruction of the magnified 3D image is produced by connecting a number of small holograms
clipped from the original FTH. Image depth capable of magnification is extended using several FTHs. Experiments
using the CGH shows that depth of the 3D image can be perceived by watching images reconstructed on many Fouriertransform
planes with different distances from the hologram. It is also shown that numbers of rays of light illuminated
from the second hologram reconstruct similar 3D images of various sizes of the same object. Distortion of the image
due to the magnification can be avoided over the wide range of magnifying power.
A new method of information reduction in hologram is described. Loss of resolution due to the information reduction is improved by superimposing spatial frequency bands of a Fourier transform hologram. Superposition of a number of identical Fourier transform holograms, which deviate each other with a small distance, forms a continuous periodic Fourier transform hologram. The second hologram for the reconstruction of an image is reproduced by repetition of a small area of the continuous periodic Fourier transform hologram. Experiments have been carried out to examine the reconstruction of 3-D images by using computer-generated holograms (CGHs). Results of the experiments show that a high-resolution image is reconstructed from the second hologram produced by superimposing spatial frequency bands. The information reduction effects on the imaging, so that the reconstructed image is spatially sampled with a constant pitch.
A method of changing in size of a three-dimensional (3D) image using a Fourier transform hologram (FTH) or a periodic FTH is described. Here, the periodic FTH is made for information reduction in hologram by superimposing a number of identical FTHs. The second hologram for reconstruction of magnified 3D images is reproduced by connecting a number of small holograms clipped from the original FTH or from the periodic FTH. Numerical calculations and experiments using the computer-generated hologram (CGH) have show that numbers of rays of light illuminated from the second hologram produce a magnified similar 3D image. Distortion of the image owing to the magnification can be avoided by reconstructing the image from a number of small holograms. Resolution, which depends on the magnifying power of the image and on the size of small holograms, is estimated by the numerical calculation.