Abstract: A two layer system can transform an arbitrary specified light field at an input plane to a desired light field at an output plane. The light field includes both intensity and phase. Such a system can be cascaded for higher level functionality. There are two computations involved. The first computes a sensitivity matrix symbolically. The elements of the matrix hold the variation in each element at the output plane with variation in each element of both phase screens. An element of this matrix is provided for reference. The second algorithm iteratively updates the phase screen values to bring the output field to that desired. On each iteration, the algorithm performs a forward computation from input to output. The phase values are updated using the sensitivity matrix and the error at the output relative to that desired.

Abstract: All-Optical logic can avoid expensive demultiplexing back to electronics in telecommunications. The term all-optical is used to described processing in which all signal paths are optical whether used for control or information. Semiconductor optical amplifiers (SOAs) can perform all optical logic because they have nonlinearity, low latency, and require low power. We use highly accurate computer models to simulate and evaluate NOR and NXOR logic gates using SOAs. These elements can act as building blocks for advanced logic systems. For example, in previous publications we described an approach to constructing arithmetic units form optical logic elements.

Abstract: A technique for detecting damage of leads arranged in a generally parallel periodic pattern, includes the following steps: directing a coherent light beam at a plurality of adjacent leads; detecting an image at a distance from the leads at which the light beam would form a diffraction image having substantially uniform intensity when the leads form a substantially uniform pattern; moving the pattern of leads and the light beam with respect to each other; and detecting damage of leads from variation in intensity of the detected image.

Abstract: A method and apparatus operate an optical memory to perform bit-slice associative memory operations by storing a plurality of keywords to define a keyword database and accessing the database by means of one of the keywords. Preferably, the plurality of keywords are unique and are used to retrieve data which corresponds individually to the keywords. Operation of the memory is by identification of a keyword, the location of which is to be determined within the memory, for example for data retrieval. The identified keyword is then used effectively as a retrieval mask to access the plurality of keywords. The keyword database and its complement are stored in an optical device with the keyword to be retrieved and its complement being stored in recall optical devices. The keyword database or its complement is repetitively swept by shifting output columnar vectors by one bit position until all bit positions have been swept.

Abstract: Optical computing cells or logic cells are constructed of two or more spatial light rebroadcasters (SLR's). Data or information images in the form of light are written into and read from the SLR's with the SLR's being controlled to process the data in a desired manner. The logic cells can be used generally to construct optical computers and are particularly adapted to the construction of optical subsystems for a digital optical computer. In addition, the logic cells can be used for performing masking, interface, intermediate storage and other operations within an optical computer. Cells made up of only SLR's can be used directly for many applications. The cells also can be modified by the internal or external addition of other optical elements for routing light between or among SLR's of the cells, processing and/or blocking light as the light passes between SLR's of the cells. Such modifications and adaptations complement cells made up only of SLR's to form a family of optical logic cells.

Abstract: An analog to digital converter, adapted to convert an optical analog signal to an equivalent optical digital signal being one of x optically presented digital numbers defined by an n-bit digital word, where X=2.sup.n. The optical analog signal is light having an intensity variable over a range from a minimum to a maximum value. The analog to digital converter comprises a linear array of comparator means, a linear array of logic means, and a linear array of decoding means. The linear array of comparator means is responsive to the light at a plurality of input positions, x, and produces binary threshold signals which respresent a one-dimensional spacial reference having a length of corresponding to the magnitude of the sensed intensity. The linear array of logic means is responsive to the binary threshold signals and produces an optical index signal which is a one-point spacial reference having a location, an index postion, corresponding to the length of the one-dimensional spacial reference.

Abstract: A computer (30) has parallel elementary processors (P1, . . . , PK) interconnected by an optical crossbar switch (32). Multiple groups of processors, each having a separate crossbar switch, are connected by exchange switches. Optical fibers (34) are used to provide high speed communication between the processors and the switch (32). The optical crossbar switch (32) is reconfigurable dynamically. The computer is reconfigurable to provide efficient implementations of signal processing and logical inference computations, including a systolic filter, a fast Fourier transform, a correlator and a matrix-vector multiplier, forward and backward chaining inference machine, and speech recognizer.

Abstract: A sonar or radar permits primary distributed scatterers that are close to the sonar or radar relative to the array dimension to be rapidly and accurately located and pertinent characteristics to be estimated, such as Doppler and complex scattering strength. The region viewed is partitioned in annuli instead of in angular pie shaped slices as is normally the case for conventional sonar. This avoids the difficulty with conventional sonar or radar of distinguishing whether a scatterer is in a side lobe or the main beam an dis preferable to conventional sonars or radars in the important case of approaching multiple scatterers, e.g. robotic vehicle sensors or torpedo terminal homing on a target, because near regions may be examined in all directions prior to further regions. Computational speed is achieved by utilizing precomputation and leaving only part of the computation to be performed in real time.