J. Phys. Radium 11, 407-412 (1950)
DOI: 10.1051/jphysrad:01950001107040700

Les couches minces dans l'infrarouge

Bruce H. Billings

Baird Associates, Cambridge, Massachusetts

Abstract
Thin films have found use in infrared light as optical filters, as bolometers and for reducing the amount of reflected light. A thin metal film can also be designed so as to wholly absorb a given wave length in the infrared band. Two types of filters are described. One is Dr Turner's frustrated reflection filter, which transmits a narrow band in the visible spectrum. The present author has extended its use to infrared and to ultra-short waves of 1 cm wavelength. A sample is demonstrated, transmitting a band 0,1 μ wide in the neighbourhood of 5 μ. The second type is the Dennison-Hadley reflecting filter, which reflects a set of infrared bands; several such filters are shown. The principle of the Dennison Hadley filter is the following : a thin metal film of 377 Ω : □ resistance absorbs all the energy in a given wavelength, when placed a quarter wavelength in front of a perfectly reflecting mirror. Such a thin film can constitute a bolometer, thus obviating the difficulty of having a satisfactory black body (all metallic black are grey in for infrared light) : Such a black is no longer needed when the thin film is of appropriate resistance.

PACS
4279W - Optical coatings.
0757K - Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors.
4225G - Edge and boundary effects; reflection and refraction.

Key words
bolometers -- optical filters -- optical films -- light reflection