Towards A Practical Updatable Optical Image Correlator

We describe initial experiments on a photorefractive based optical image correlator which employs a frequency doubled, pulsed Nd:YAG laser with a pulse length of 10 nsec to write a phase grating into a crystal of bismuth silicon oxide. The correlation of simple binary images has been demonstrated and measurements indicate that the rise time of the correlation signal is less than 200 nsec. The vibration stability of the pulsed system is much greater than previous CW systems.