Thermography is not a new technology, but rather an older one with an ever-increasing number of new applications. For many years it has been known that when objects get warm they give off Radiation. The hotter they get, the more radiation is given off. Some of this Radiation is Visible, some is not.
Types of Radiation
This diagram shows the relationship of various forms of radiant energy. The expanded scale at the bottom represents the wavelengths of visible light and the infrared spectrum.
(Diagram and Description Courtesy of Thermal-Vision.com (USA))
Thermography is a Science that focuses on the Infrared (or Heat) portion of this Radiation. With special Cameras that only record the Infrared it is possible to detect very slight variations in temperature.
It should be emphasized that this is a "Nondestructive" Technology that has a myriad of uses that include Medical, Geological, Mechanical and Electrical. Perhaps the Biggest application in our Trades is that through regular Thermal Inspections many problems (or Potential Problems) can be detected before they become serious. It should be a part of any Serious Preventative Maintenance Program.
Special Thanks to Thermal Vision (Ireland) and Thermal Vision (US.) for Providing Images and Information.