<title>IR imaging of a point target through inhomogeneous media along a slant path of 2.3 km</title>

Abstract

The influence of atmospheric vertical structure variations on infrared propagation and imaging has been analysed based on measurements taken during the VAST92 experiment in the German Alps. A blackbody source at a distance of 2.3 km and an altitude of 1 .8 km was detected against various sky backgrounds by a scanning DUWIR camera from GEC and a staring PtSi-camera from Mitsubishi. The propagation media has been characterized in detail using supporting atmospheric parameter measurements from lidars, a transmissometer, a spectral radiometer, aerosol counters and various meteorology stations at different elevations. The analysis of these measurements is presented. Two different weather conditions have been selected for analysis in this report: a dynamic cloud layer between sensor and point source, and a clear and stable situation with blue sky in the background. The recorded image sequences of the point source have been analyzed with respect to spatial and temporal fluctuations. Emphasis has been placed on the comparison of the two wavebands (3-5 im and 8-12 jim) and on comparison of different sensing techniques. The results are currently being used to improve and validate point detection algorithms.