Abstract
The range of applications in which remote detection of chemical compounds is used extends from monitoring of technological processes through diagnostics of industrial installation and environmental control up to military applications. The methods and the devices used for the passive detection of selected gases are presented. The change in the signal reaching the camera caused by the presence of gas was calculated. The successful detection can be achieved if the absorption (or emission) of a gas cloud, located between object (background) and the camera, causes signal change greater or equal to noise equivalent temperature difference (NETD) of the camera.