Abstract

The subject of diffractive optics has been studied for many years. Some of the applications in this area are the use of Fresnel zone plates in x-ray or gamma ray imaging, modulation zone plates in laser machinery, computer generated holograms in optical interconnects and optical computing, and microlenses in laser beam and LEDs focusing. However, there is not much attention in spatial light modulator (SLM) based dynamic diffractive optical elements. In this paper, we would like to study the design of SLM based kinoform lenses in dynamic electro-optical imaging systems. The phase relief profile of a spherical lens, usually called a kinoform lens, is implemented onto a continuous phase SLM. The focal length of the kinoform lens can then be changed at the frame rate of the SLM. This dynamic lens will be incorporated with other refractive lenses to give an electro-optical imaging system which does not require any movable mechanical parts for focusing and/or zooming. More importantly, focusing/zooming can be accomplished at the frame rate of the SLM, typically in the order of 30 to 40 ms per frame for a commercially available nematic liquid crystal light modulator. This speed represents at least an order of magnitude faster than that required in a conventional focusing or zooming system based on mechanical motion of lenses.

© 1992 Optical Society of America