Dispersion of Air in the Near-Infrared*

Abstract

Methods of computation are described for determination of the refractivity of air from measurements made with a corner-reflector Michelson interferometer. Results are given for eleven vacuum wavelengths from 7034 to 20 587 A. These results support Svensson’s conclusion that Edlen’s dispersion formula may be increased in precision by raising it slightly in the near-infrared. They indicate however an increase of 0.12×10-8×(3.35 µ-2-σ2) over Svensson’s formula. A question is raised as to the existence of appreciable variations, perhaps seasonal in nature, in the refractivity of outdoor air.