Book Description

An optical data processing study was performed to determine the value of the use of present day coherent optical processing techniques on selected AFFDL data processing problems. Optical, digital and analog implementation of Power Spectral Density, Cross Spectrum, Auto and Cross Correlation, Transfer Function, and Filtering (Convolution) were considered for a wide variety of input data: from low frequency Clear Air Turbulence (cycles/hour) to high frequency acoustic data (10 Hz). A sample problem supplied by AFFDL was analyzed by in-house optical, digital and analog computers to demonstrate the degree of computational equivalence. Next a study of twelve processing areas at Flight Dynamics Laboratory was performed to uncover promising areas for Optical Processing. Although most requirements could be met all twelve users reported a dynamic range requirement 10 dB or more than that which is available in established optical processing technology. Areas in which optical processing shows advantages over digital processing, viz. , two-dimensional Fourier transforms and high BT products were not desired nor within the current mission of the laboratory data. Cost data for the three processing methods were generated. For large volume processing, the digital and optical implementions were found to be roughly equal and less than the cost of analog equipment for spectrum analysis. The digital method is found to be system cost effective in that once a special purpose Fast Fourier Transform (FTT) computer is purchased to generate power spectrum, and other functions can be calculated with negligible increase in cost.