REAL-TIME SPECTRALLY EFFICIENT TARGET IMAGING

Abstract

To enhance the visibility of remote objects under test at Air Force testing facilities in adverse weather conditions, the Air Force Flight Test Center (AFFTC), Edwards AFB, California, contracted with Physical Optics Corporation’s (POC) Applied Technology Division, Torrance CA, to investigate a realtime spectrally enhanced imaging prototype system. When installed on an optical target tracker, this system will automatically adjust its spectral transmission in such a way that the intensity of the background illumination will be reduced significantly while providing minimum reduction of the light reflected from a detected target. A laboratory prototype of this system was developed under a Small Business Innovative Research (SBIR) Phase I contract. The prototype consists of the optical part that will be attached to the large tracker lens and to a portable computer. The key element of this system is an Acousto-Optic Tunable Filter (AOTF) that is capable of quickly varying the shape of its spectral transmission curve in the entire visible range under computer control. The developed system automatically analyzes the spectral signatures of the background and of the selected object of interest. It calculates a spectrally matched filter for the background suppression and target contrast enhancement. This filtered data then goes directly into the optical channel with the minimal computer image processing. The resulting image with the enhanced target contrast can be displayed in real time on a common computer monitor and can be recorded by a VCR. The performance of the laboratory prototype demonstrated enhancement of the visibility of objects immersed in a scattering medium. Successful development of a working system will make flight testing of military equipment more informative and less expensive. It will reduce the dependence of the flight test program on the weather conditions and will allow for collecting more data by providing real-time images with enhanced target visibility.