The amount of radiated energy is a function of the object's temperature and its relative efficiency of thermal radiation, known as emissivity. The amount of radiated thermal power is determined by the equation. There are a variety of scanning techniques and IR detectors found in instruments today. Temperature resolution, the ability to measure small temperature differences, can be as fine as 0.1 C. Spatial resolution, the ability to measure temperatures on small areas, can be as fine as 15 microns. Temperature sensitivity and measurement range cover broad ranges.
Applications extend from microelectronic levels to scanning wide areas of the earth from space.
Airborne systems can be used to see through smoke at forest fires. The performance requirements will dictate the type of system needed. Steady state analysis is normally used in determining reliability characteristics. It will certainly be costly. As you'll see later, prices for thermal imaging systems can extend over a very broad range and performance requirements will be the determinant of system cost.