Passive optronic systems - Thermal cameras

The development of thermal imaging techniques for military applications stemmed from the growing need for armed forces to be able to fight 24 hours a day, i.e. night and day, and in difficult observation conditions (camouflaged objects, vision through fog or smoke, etc.).

The first generation of thermal imaging cameras was designed around modular systems, enabling all kinds of equipment to be produced for defense requirements, in the USA (US-CM from 1975), Great Britain (TI-CM, 1978) and France (SMT, 1978), with Germany preferring to adopt the American system. In France, SAT of the Sagem group and Thomson-CSF-Optronique are the leaders in this technology. Today, equipment based on the SMT system equips the armed forces.

The second generation first appeared in Europe in the late 1980s, to meet the needs of third-generation anti-tank systems based on medium- and long-range missiles. New detector technologies with associated electronics in the focal plane (such as IR-CCD, IR-CMOS, etc.), which had to be developed to meet the required performance levels, made it possible to produce arrays with more than a thousand elements in the 8-12 µm band, and two-dimensional arrays with more than 512 × 512 elements in the 3-5 µm band.

Technology is already evolving in several directions:

• towards lower costs on a like-for-like basis ;

• towards low cost, with uncooled matrix detectors, enabling dual applications, i.e. both civil and military;

• improved resistance to laser countermeasures (non-detectability and anti-glare);

• to multispectral or monospectral cameras with scalable wavelengths.