Abstract

Conoscopic holography is an incoherent holographic technique based on light propagation in uniaxial crystals. Let a monochromatic circularly polarized point source radiate light in a cone. A ray inside this cone can be decomposed in two components of equal intensity, the ordinary and extraordinary waves. The optical path differences between these two waves is given (to within a very good approximation) by a quadratic function of the angle. The pattern produced after a circular analyzer—the conoscopic pattern—is a Fresnel zone lens. Now, if an object is placed at the input of the system, the output will be the convolution of the object intensity distribution with a Fresnel zone lens, i.e., a hologram. One of the principal advantages of this technique is the possibility to record a Fresnel hologram on a TV camera and to digitize and send the data, in real time, to a computer. The system can be used directly to perform matched filtering in two or three dimensions; alternatively, the hologram can be processed by the computer to retrieve the 3-D information.

© 1986 Optical Society of America