1. ABSTRACT This paper describes the design and fabrication of a high performance optical vectormatrix coprocessor for optical computing research applications. The optical vector-matrix coprocessor is configured to multiply an 8-element vector by an 8 X 8 matrix with a throughput rate of 1 MHzeffectively achieving a processing rate of over 100 Mops. The Vector-Matrix Coprocessor interfaces to an industry standard Personal Computer with a single card and is controlled by software written and compiled in the ANSI C language. All data input and output to the coprocessor are in 8 bit digital words. An 8 to 12 bit look up table is provided for each input channel to provide real time linearization of analog optical data representing input values through the optical system. The optical signals representing calculation values are detected and received by a switched capacitor integrating filter to reduce detection bandwidth and reject broadband noise. INTRODUCTIONOptical matrix processors were developed to exploit the high degree of parallel connectivity inherent in free space optical interconnection. Researchers have proposed and investigated optical algebra processors for at least three decades1'2. Many different architectures and implementations have been investigated in as many different laboratories. Recent advances in multi-channel modulators3, light valve technology, and detectors4 have potential to make these systems practical for many applications. Specifically, vector-matrix processing can give much higher throughput than digital approaches and many applications exist were performance can be bought with speed even at the price of accuracy or dynamic range5'6. Earlier works have developed similar and more powerful processors, but have used expensive and bulky approaches that rely on pulsed lasers7 or systolic algorithms8 that limit their application to very special missions. This paper describes the development of a high performance Optical Vector MatrixCoprocessor that is constructed as much as possible with off-the-shelf components. It incorporates advances in optical technology for its laser source, vector modulator and detector array while leveraging the increased the performance and reduced cost of the new wave of digital electronics. The state of the art of digital to analog to digital conversion is increasing daily to meet the promise of digital video to the home. The practical application of photonic systems has greater promise due to the steady development of its component technology. The OVMC is designed to use these advances for a flexible and programmable test bed to aid the development a new generation of processors. Further, its architecture is chosen to be simple and to be applied to a much smaller package volume for its application to a large range of missions were a linear algebra coprocessor is only a part of a much larger system.

Radiometer spectrometers are used in millimeter-wave radio astronomy for the spectral measurement of molecular rotational transitions. The spectrum of interest spans 10's of GHz and the measurement time is large in order to obtain useful signal-to-noise ratio. The low power/channel and simplicity of acousto-optic technology has led to the current development of acousto-optic spectrometers (AOS) with 1 GHz bandwidth and 1000 channels. Additional AOS bandwidth and channelization is needed to increase spectral coverage, reduce overall data acquisition time, and accommodate multibeam antennas. A multichannel acousto-optic spectrometer (MCAOS) for radio astronomy spectroscopy applications has been developed with 4 channels that can process signals from 4 separate sources simultaneously. The bandwidth of each channel is 1 GHz and the frequency resolution is 1 MHz, providing simultaneous processing over 4,000 1 MHz channels. The design and initial performance of this instrument is described. Design considerations for future wider bandwidth MCAOS's are also presented.

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