Position, Scale, and Rotation Invariant Holographic Associative Memory

摘要

This thesis investigates an all-optical position, scale, and rotation invariant (PSRI) holographic associative memory employing phase conjugation. The PSRI feature space is the In-polar representation of the magnitude of the Fourier transform, of the objects. This representation is generated using a coordinate transform computer generated hologram. Diffuse Fourier transform holograms of the PSRI feature space and the use of angularly multiplexed references allow access to the correlation domain where the nonlinear properties of the phase conjugate mirror, self-pumped BaTiO3, reduces cross-correlation noise and provides object discrimination. The self-pumped phase conjugate mirror is characterized and a procedure for consistent production of high diffraction efficiency holograms is developed. The holographic associative memory is constructed and its operational parameters are defined. One object is stored in the memory because of limitations on the size of the Fourier transforming optic and the properties of the ground glass diffuser. Fast optics and a custom designed phase diffuser are recommended to alleviate this system characteristic. (JHD)