Abstract

The cryogenically cooled detectors used in thermal imaging systems are in effect looking at thermal or heat sources in object space. Any uniform change in the thermal irradiance over the field of view will reduce somewhat the system sensitivity. However, a far more severe and sometimes devastating problem occurs when the thermal irradiance changes or modulates across the field of view. This can cause false images, bright bands, and other cosmetically undesirable effects, which in the worst cases can be tracked or otherwise processed by the system as if it were a real image. These effects are especially evident in scanning systems, and we show how the basic scanning geometries can lead to these image anomalies if appropriate care in the optical as well as the mechanical design is not taken.

© 1988 Optical Society of America