Abstract: Pulsating infrared radiation source 50, which is so thin as to make its thermally stored energy less than the energy radiated during each pulse. This makes the source cooled by its own heat emission. Such sources have thicknesses commensurate with the wavelengths of infrared radiation. To avoid interference effects, the source's optical thickness may be made to equal a multiple of half wavelengths of the desired radiation. With the source mounted in a housing 53, efficient radiative cooling is obtained using windows 54 and 55 to each side. This makes it possible to extract infrared radiation from either face of the source.

Abstract: Infrared radiation source arrangement, in particular for use in infrared spectral analysis. To an electrically insulating substrate (2) there is applied one and preferably at least two separate electrically conductive films (2a, 2b) adapted to be heated by application of a time dependent electric current thereto. Tow or more films may form a radiation group (array) in which each film (2a, 2b) is adapted to be energized separately with electric current from an electric drive circuit (1) for applying a time dependent, preferably pulse shaped electric current to the film or films, so that infrared radiation pulses are emitted. The electric current is time controlled in order that the radiation pulses from the respective films may be distinguished from each other in a detector (6). The thickness of the substrate and the thermal conductivity, specific heat and density of the substrate material are so chosen that the thermal time constant is adapted to the pulse frequency range of the drive circuit.