Infrared (IR) radiation is always present in our world - be it day or night. Every solid, fluid or gaseous body, merely due to its own temperature, emits radiation which lies in the infrared range (thermal radiation).
Infrared radiation is not visible for human beings. Only with IR cameras it is possible to take IR images. The technology of IR cameras is complex and is mastered by only very few companies worldwide. High-performance IR cameras are available just for a few years now, and their technology is undergoing a continuous progress. The development trends go to higher definition, speed and sensitivity as well as multi-spectral technology (dual-band and dual-color IR cameras).
Despite the fact that the infrared lies close to the visible light, an infrared image carries quite different information than a visible image. Infrared images are the result of different overlaying effects which sometimes are difficult to interpret.
For scientific and technical applications, the infrared is interesting because by investigating the infrared radiation one can gain information about the thermal properties of samples under test. Infrared imaging has found its way into numerous technical and scientific areas and is applied successfully, for example in non-destructive testing (NDT). But in many areas IR technology is yet at the beginning and it offers a lot of chances for new discoveries and developments.