A thermographic camera or infrared camera is a device that forms an image using infrared radiation, similar to a common camera

Camera

A camera is a device that records and stores images. These images may be still photographs or moving images such as videos or movies. The term camera comes from the camera obscura , an early mechanism for projecting images...

 that forms an image using visible light

Light

Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

. Instead of the 450–750 nanometer range of the visible light camera, infrared cameras operate in wavelength

Wavelength

In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...

s as long as 14,000 nm (14 µm).
In 1929, Hungarian physicist Kálmán Tihanyi

Kálmán Tihanyi

Kálmán Tihanyi , was a Hungarian physicist, electrical engineer and inventor. One of the early pioneers of electronic television, he made significant contributions to the development of cathode ray tubes , which were bought and further developed by the Radio Corporation of America , and German...

 invented the first infrared-sensitive (night vision) electronic television camera for anti-aircraft defense in Britain.
The first conventional IR camera, the "Evaporograph", was declassified around 1956.
Infrared energy is just one part of the electromagnetic spectrum

Electromagnetic spectrum

The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....

 that encompasses radiation from gamma rays, x-rays, ultra violet, a thin region of visible light, infrared

Infrared

Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

, terahertz waves

Terahertz radiation

In physics, terahertz radiation refers to electromagnetic waves propagating at frequencies in the terahertz range. It is synonymously termed submillimeter radiation, terahertz waves, terahertz light, T-rays, T-waves, T-light, T-lux, THz...

, microwaves, and radio waves

Radio waves

Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers. Like all other electromagnetic waves,...

.