Issues and Solutions to Midwave Staring FLIR Performance Measurement Over Background.

摘要

Following an in-flight squawk for poor and unstable image quality during pre-deployment operational testing, the Edwards Benefield Anechoic Facility (BAF) electro-optics laboratory set about to duplicate what was suspected as a background temperature related sensitivity issue with relevant sensors, specifically midwave-FLIRs. The system in question was designed in 1992 and fielded in 1994, relying on existing performance models which indicated the performance should have changed only slowly and tolerably as background temperature varied. However, experience showed considerable sensor change in sensitivity related to background flux even over the small 20 deg. C temperature variation at Edwards from late afternoon and later in the evening. Note that real operational environments can involve backgrounds from -40 deg. C to +40 deg. C. These were the limits used for this particular system. A reasonable specification for sensors of this type to make them operationally suitable would be from -40 deg. C to +100 deg. C to accommodate hot environments populated with operating vehicles. Also that such backgrounds can even occur within a few frames of video as sensors observe a cold sky and then a hot desert. Multiple scenarios can stress sensors between these limits. No piece of commercial test equipment existed that is specifically designed to make sensitivity measurements on tactical sensors at other than room temperature. As a result of test equipment limitations and rosy model predictions, such measurements have never been made, with designers relying instead on the industry standard performance model to predict performance above and below room temperature. Subsequent lab data on multiple sensors at Edwards showed this reliance to be unsubstantiated. This paper describes the actual testing methodologies and also describes progress toward development of a more appropriate test device and methodology to support retrofit of existing sensors and development of future ones.