Images with partial and complete contrast reversal have been retrieved from a single image recorded in a lithium niobate crystal. The input image, a grey tone transparency, is modulated with the help of two diffracted orders of a Ronchi ruling. The same two orders are used to read the crystal. The relative amplitude of these orders is altered with the help of a linear polarizer, and this produces variable tones in the output image. Partially coherent light can be used at both the writing and the reading stages.
© 1981 Optical Society of America
R. Grousson and S. Mallick, "Image contrast reversal with a photorefractive recording medium," Appl. Opt. 20, 1719-1723 (1981)