Abstract: An optically implemented technique which generates the correlation function f two electrical signals. A reference signal is used in conjugation with an acousto-optic device to generate an optical field which is incident on a photorefractive crystal. This produces in the crystal a reflection phase conjugate wave front reconstructing volume hologram. A retropropagating reconstructed optical field passes back through the device which contains a second signal. This optical field is then focused onto a photodiode. The time varying component of the photodiode output is the correlation of the two signals.