Abstract

The optical implementations of associative memory based on various thresholding and feedback schemes have been demonstrated recently.^1,2 We here show a real time parallel optical associative memory system implemented with a KNSBN:Co crystal as recording medium and liquid crystal electrooptic switched as a reflective thresholding device to provide binary thresholding response. In our experiment, two original images, HIT and XXY, are stored in KNSBN:Co crystal at the Fourier plane through interfering with angular multiplexed reference beams. When the system is addressed by a half of one of the stored objects, the detecting beam split from its autocorrelation beam is higher than the thresholding power of 14.7 µW of the liquid crystal electrooptic switch, but the detecting power of its cross-correlation beam is lower than the thresholding power. The autocorrelation peak corresponding to the partial input switches the liquid crystal electrooptic switch into the transmissive state. Switching the liquid crystal electrooptic switch allows the counterpropagating beam to read out the hologram and a complete image is reconstructed. Thus, the no iteration system demonstrates the ability to retrieve the correct memory element without crosstalk.

© 1989 Optical Society of America