1 August 1989 Position, Scale, And Rotation Invariant Holographic Associative Memory
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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.
Kenneth H. Fielding, Kenneth H. Fielding, Steven K. Rogers, Steven K. Rogers, Matthew Kabrisky, Matthew Kabrisky, James P. Mills, James P. Mills, } "Position, Scale, And Rotation Invariant Holographic Associative Memory," Optical Engineering 28(8), 288849 (1 August 1989). https://doi.org/10.1117/12.7977045 . Submission:

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