Veridian Erim International, Inc.

Coherix, Inc.

Veridian Systems

Carl C Aleksoff

Alex Klooster

An off axis paraboloid mirror is used to provide object illumination in an interferometric imaging system. The light from an object illumination light source diverges from a point apart from the focus point of the paraboloid, proceeds to the parabolic mirror surface, and is reflected as a nearly parallel beam to illuminate the object.

Off-axis paraboloid interferometric mirror with off focus illumination

A Tapped Optical-Fibers Processor (TOP) for correlation and autocorrelation facilitates the processing if radar and SAR (synthetic aperture radar) signals, allowing fine resolution to be obtained without fast front-end sampling while significantly reducing digital computational burdens. Particularly in conjunction with radar signal processing, the input signal may be composed of the sum of at least two or more signals, in which case the output may include the autocorrelations of both inputs as well as the generation of a cross-correlation of the two autocorrelations. In terms of hardware, a signal processor according to the invention preferably includes a coherent laser source operating at a carrier frequency; a modulator to insert an input RF signal into the carrier; an optical fiber radiator composed of a fiber with taps that radiate the modulated optical signal; a lens to perform a spatial Fourier transformation on the radiated signal; and a detector array to output the transformed signal to a digital processor for additional signal processing. In any case, the two input signals may be electronically or optically combined.

Correlators and cross-correlators using tapped optical fibers

A signal analyzer is being developed that is based on a periodically tapped optical fiber. The spatial distribution of taps produces a waveform that is weighted by a spatial light modulator (SLM), optically Fourier transformed, and then detected with a video camera to continually display the power spectrum of the signal propagating in the fiber. Alternatively, a digital holographic technique can be implemented that avoids using a SLM. The analyzer resolution and bandwidth is dependent on the distribution and number of taps. Taps have been formed in the core of fibers using UV light. Both single step beamsplitter and localized phase grating taps have been generated. Bragg grating taps tilted at 45 degrees with respect to the fiber axis were generated in order to diffract light directly out of the side of the fiber.

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Dexter, MI, United States of America

Carl C Aleksoff