Fizeau interferometer profiles at finite acceptance angles

Abstract

Instrument profiles of the wedge or Fizeau interferometer are determined under practical conditions. The appearance of subsidiary maxima on the high order side of the central maxima is confirmed, and the behaviour of these is noted as the solid angle of acceptance is varied. From these calculations it is inferred that the acceptable range of use of the instrument could be much wider than was previously believed and that the instrument can be of considerable use in measuring small shifts in spectral emission lines.