DYNAMIC SPECTRAL FILTRATION IN ELECTRO-OPTICAL SYSTEM OF TARGET DETECTION

Abstract

This paper generalizes and develops the principles of dynamic spectral filtration, which is a further development of imaging spectroscopy. Electro-optical systems with dynamic spectral filtration in contrast to imaging spectrometers realize controlled spectral filtration, which ensures maximum suppression of the spectral components of background radiation with a minimum attenuation of the target optical signal in the pre-detector area. The purpose of the article is to generalize and develop the principles of dynamic spectral filtration in the interests of creating electro-optical systems of targets detection by spectral features. The problem of optimal selection of optical signals from background noise has been reduced to solving a problem of signal detection with a priori known parameters used in radiolocation theory. The article states the principles of dynamic spectral filtration of optical radiation. It also describes an algorithm for optimal detection of targets by spectral characteristics and carries out a synthesis of an optimal optical signal detector. The paper defines the quantitative characteristics of the detector, that for a given false alarm level allows to determine the conditional probability of correct detection of the targets of observation depending on the signal-to-interference ratio. The quantitative characteristics of the detector were obtained on the assumption that the signals of the target and the background obey the normal distribution law, and their correlation characteristics (the correlation matrices of the background and the target) are equal. The work experimentally establishes the possibility of creating a controlled acoustooptic selection device providing a spectral selection of two optical signals differing in spectral composition by varying the amplitude of the frequency components of an ultrasonic wave. In this case, three lasers operating in the red, green and blue regions of the spectrum were used as the source of optical radiation. In the course of the experiment, spectral selection was provided by diffraction of polychromatic laser radiation by multifrequency ultrasound. The efficiency of the filtration process was determined by the contrast value before and after filtration. It was experimentally established that, in the presence of three spectral channels of selection, it is possible to increase the contrast at the output in several times.

Keywords

• acoustooptical filter
• dynamic spectral filtration
• electro-optical system