Instrumental profile of a triple Fabry-Perot interferometer for use in solar spectroscopy.

A universal filter for use in solar spectroscopy is under development, consisting of a computer-controlled triple Fabry-Perot interferometer. This paper explores the extent to which the performance of such a filter is degraded by off-axis effects under the intended conditions of use. Computed instrumental profiles for both on-and off-axis cases are presented. The calculated bandwidths range from 0.021 A to 0.047 A at eight wavelengths of interest in the visible region of the spectrum.