White-light image processing with LiNbO_3

Iron-doped LiNbO3 has been employed to carry out some image processing operations such as sum, difference, or multiplication of two intensity distributions. Contrast enhancement or reversal of a signal can also be obtained. The signals, modulated on low-frequency carriers, are imaged on the ferroelectric crystal, and this disposition permits the use of white light for both writing and reading the information. An advantage of our technique is that the writing of information is accomplished once and for all, and the various image processing operations are carried out by suitable manipulations at the reading stage. A further advantage is that the output information can be displayed in color. The limitations on the source size and its spectral spread imposed by the finite thickness of the recording medium have been analyzed, and some experimental results are given.