Spatial light rebroadcaster bit-slice word-addressable holographic memory

Three-dimensional object recognition by use of a photorefractive volume holographic processor

We present a photorefractive volume holographic processor for recognition of three-dimensional (3D) objects. The templates are recorded by use of a volume hologram in a photorefractive LiNbO(3):Fe crystal located at the Fresnel diffraction region and correlated in real time with a 3D object illuminated by coherent light. Experimental results for recognition of 3D objects are presented and discussed. To the best of our knowledge, this is the first time a photorefractive volume holographic technique for 3D object recognition has been reported.

Optical perceptron learning for binary classification with spatial light rebroadcasters

Binary classification of an object in a two-dimensional image is considered. A spatial light rebroadcaster is shown to be advantageous for learning in this case because it can store the weights and permit upward and downward adjustments. Two learning algorithms, based on the perceptron, are considered. A modification of the perceptron algorithm is developed so that only positive weights are needed. This is convenient because light intensity is positive only. The modified algorithm is shown to converge in a finite number of steps for positive linear separable classes. Optical experiments show the classification of four characters in two groups, in which alternative groupings are used to show robustness. In the second group of experiments the complements of the two-dimensional characters are used, and the convergence is equally fast. Adding the results from the original and complementary patterns provides a discrimination superior to that obtained using either on its own.

Optical adder that uses spatial light rebroadcasters

We show novel experimental results for an all-optical cascadable module that consists of a spatial light rebroadcasters, an image intensifier, and a liquid-crystal light valve. The module may be used for all-optical logic, memory, or arithmetic. Previous experimental systems involving spatial light rebroadcasters use a video camera and computer to overcome their lack of cascadability. The results of laboratory experiments show correct operation for a half-adder constructed from the cascadable module. Optical setups are proposed for constructing all-optical parallel ripple-carry and bit-slice full adders by using a single optical half-adder.