Abstract: Associative holography memory apparatus is disclosed which employs a hologram and two phase conjugate mirrors. The mirrors are arranged to form a conjugate resonator whereby the output image from the apparatus tends to converge to that stored image most closely associated with an input image. Alternate embodiments are described which employ a multiple storage and erasure hologram, and which employ only a single phase conjugate mirror.

Abstract: A phase conjugate resonator (PCR) (2) employing a phase conjugate mirror (PCM) (4) provides high resolution spatial detection of individual locations in a two-dimensional optical array which exceed or fall below a threshold level. The optical intensity profile under investigation is imposed onto an input erase beam (18) to the PCM (4). The erase beam (18) is directed parallel to the PCR axis (16), thereby preventing walkoff. The PCR (2) oscillates at those locations where the erase beam's optical intensity is below a threshold level. The spatially modulated optical output may be read out with multiple detectors or an imaging system, or the cumulative area output of the PCR can be read out with a single detector (28) to characterize the intensity profile relative to the threshold.

Abstract: Optical devices are disclosed which rely upon Stark-induced resonant, tunable, and saturable birefringence and dichroism to provide both digital and linear amplitude optical modulators, optical shutters, tunable optical filters, and optical cutoff limiters. A Stark cell is disposed along a light beam path between two crossed polarizers with its electric field direction at 45.degree. to the polarizer pass directions. The Stark cell contains a medium exhibiting a dichroic absorption resonance at a predetermined frequency as well as birefringence at frequencies slightly above and slightly below the frequency of the absorption resonance. By applying an appropriate control voltage between the Stark cell electrodes, an electric field is generated within the Stark cell to tune the absorption resonance to overlap the frequency of an input laser beam and thereby vary the transmission through the device from maximum near resonance to zero at frequencies far away from resonance.