Improved electroholographic display using liquid crystal devices to shorten the viewing distance with both‐eye observation

Abstract

We are constructing an electroholographic display system using liquid crystal devices (LCDs) as spatial light modulators to control the wavefront of laser light for reconstructing 3-D images. A wide horizontal viewing zone is secured with five special LCDs set up in a continuous series by a half mirror. The viewing distance is still considerably long, however, and this distance reduces the perception of image depth. Thus, we suggest setting a field lens at the center of the reconstructed image to shorten the viewing distance. Since the reconstructed 3-D image becomes considerably distorted by the use of a field lens, we propose predistortion to compensate. Each LCD is assumed to have 3200 (H) X 960 (V) pixels with 28 (H) X 56 (V) µm pixel pitch. Although, this LCD is still in trial production, we have confirmed the reconstructed image by replacing the LCDs with computer-generated holograms (CGHs) recorded to five photographic films having the same specifications as real LCDs. In this way, we verified the reconstructed image [50 (W) X 50 (D) X 100 (H) mm] with off-axis, horizontal parallax only. This image can be observed with both eyes at a distance of 900 mm, and we can perceive the image depth sufficiently.