Abstract

Kinoform is a computer generated phase hologram that acts as a kind of Fresnel lens that changes the phase of the illuminating wave by its thickness variation. For this reason, kinoform has the advantages of high light efficiency and effective utilization of the image space but the disadvantage of tedious photographic processing during its construction. When the kinoform is displayed on a liquid crystal television (LCTV) that operates in a phase modulation mode, the thickness variations of the conventional kinoform can be replaced by the birefringent effect of the liquid crystal molecules. The technique requires a modulation depth of about 2π, which several commercially available LCTVs are unable to attain. In this paper, we will discuss an experimental technique for generating an LCTV kinoform where the modulation depth is limited by π. The major drawback of the π phase variation is that it reduces the diffraction efficiency as well as the space–bandwidth product to some degree, compared to a 2π modulation. The verification of this drawback will also be reported.

© 1992 Optical Society of America