An optical correlator, believed to be novel, adds an x-y mirror image to the input and filter images to perform convolution involving amplitude and phase. The resulting real Fourier transform filters can be loaded into a liquid-crystal device (LCD). In contrast, a complex filter would require high-resolution film. A Hilbert transform and a point source are applied at the filter plane to reduce filter storage and LCD loading time by a factor of 2. An optional spatial filter removes an offset intensity and squares the result. Filters have only twice the number of pixels of the images. Analysis is verified by computer simulation, and performance is discussed.
Pres tack inversion with point-source plane-layer modeling has many advantages over poststack or normal incidence inversion. For example, it permits the determination of absolute compressional and shear velocities, density variations, and the accurate accounting of inter bed and surface multiples. I neglect shear effects in this paper by assuming that they are adequately suppressed by velocity filtering. In the forward modeling step, a spherical wave expansion into plane waves is used to account for the point source. The plane-wave reflection response for a set of plane layers is extended to the nonnormal incidence case. I use a Hankel transform to account for cylindrical symmetry. Generalized linear inversion is used because the fast recursive approaches available for normal incidence inversion are no longer applicable. I provide the derivation for the required derivative matrix, and I take into account the band-limited nature of the data in frequency, time, and space.
A new device, a spatial light rebroadcaster, is described that can have optical disk resolution and high speed. Experimental results demonstrate resolution, speed, linearity, logic operation, and arithmetic computation. The device is suitable for optical computing, in particular for memory systems. Optical masking for controlling memory recall and 100 x 100 matrix-vector multiplication are demonstrated. A one pass optical heteroassociative memory system was assembled that uses an optical outer product formulation to store associated 32-bit vectors. Recall is achieved by optical matrix-vector multiplication. The results show the suitability of these devices for memory systems in optical computers.
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