Abstract

We report an experimental work that demonstrates reconstruction of the phase information of a wavefront, constrained to have predetermined intensity distributions at both object and Fourier planes. A wavefront that satisfies the intensity constraints is generated as oscillations build up inside a double-phase conjugate resonator. Two transparencies at front and back focal planes of a lens provide the constraints on the intensity distribution. Theoretical considerations show that the two transparencies should have a binary intensity transmittance. To process wavefronts that have continuously varied amplitude, transparencies forming a halftone screen version of the needed constraints should be used. Low pass filtering at the viewing end of the system generates the desired wavefront. A single crystal of BaTiO₃ is used as a recording medium. To get a double-phase conjugate resonator, the optical system is folded to form a closed ring configuration. Experimental results that demonstrate reconstruction of phase information have been obtained using two circular apertures of different radii. Two possible solutions are a spherical wavefront with a limited bandwidth and its phase conjugate one. Oscillations built up have included both solutions and a slow transfer from one solution to the other has been observed.

© 1986 Optical Society of America