Abstract
An all-optical holographic memory was recently proposed by researchers at the Hughes Research Laboratories. This paper details the investigation into the characteristics of that system and an extension to a position, scale, and rotation invariant (PSRI) holographic associative memory. The PSRI feature space is the en-polar representation of the square magnitude of the Fourier transform, IF(fnr, fo)I2, of the objects. This representation is generated optically using a coordinate transform computer-generated hologram. Angularly multiplexed, diffuse Fourier transform holograms of the PSRI feature space are characterized as the memory unit. Distorted input objects are correlated with the hologram, and a nonlinear phase conjugate mirror, self-pumped BaTiO3, reduces cross-correlation noise and provides object discrimination. The self-pumped phase conjugate mirror is characterized, and high diffraction efficiency bleached holograms are used in the place of thermoplastic film. Applications of the memory are also presented.
