Thermographic camera

A thermographic camera (also called an infrared camera or thermal imaging camera) is a device that forms an image using infrared radiation, similar to a common camera that forms an image using visible light. Instead of the 400–700 nanometer range of the visible light camera, infrared cameras operate in wavelengths as long as 14,000 nm (14 µm). Their use is called thermography.

History

Precursors

Infrared was discovered in 1800 by Sir William Herschel as a form of radiation beyond red light. These "infrared rays" (infra is the Latin prefix for "below") were used mainly for thermal measurement. There are four basic laws of IR radiation: Kirchhoff's law of thermal radiation, Stefan-Boltzmann law, Planck’s law, and Wien’s displacement law. The development of detectors was mainly focused on the use of thermometer and bolometers until World War I. Leopoldo Nobili fabricated the first thermocouple in 1829, which paved the way for Macedonio Melloni to show that a person 10 meters away could be detected with his multielement thermopile. The bolometer was invented in 1878 by Langley. It had the capability to detect radiation from a cow from 400 meters away, and was sensitive to differences in temperature of one hundred thousandth of a degree Celsius.