A scheme is presented that uses cascaded two-beam coupling interactions to optically generate a log transform. By optimizing the two free parameters of gain coefficient and beam intensity ratio for each interaction region, we have generated a computed output intensity that is the natural log of the input intensity, with an accuracy of better than 1% over a four decade dynamic range.
© 1990 Optical Society of America
Robert W. Eason and Stephen W. James, "Logarithmic output from cascaded two-beam coupling interactions in photorefractive crystals," Appl. Opt. 29, 3362-3364 (1990)