Knowledge Bank

A variable depth lamellar grating interferometer similar to the one described by Genzel and $Weber1$ has been constructed at The Ohio State University. It can be used, with periodic variation of the grating depth, either as an order separator for a far infrared grating spectrometer, or as a direct-reading spectrometer by itself. This interferometric modulator designed primarily to serve as a pre-monochromator, will be described. Expressions for the instrumental line shape will be given, for the error-free case and for some cases in which certain errors are assumed to be present. Calculated and observed instrumental line shapes will be compared. The effect of errors on the modulator's performance will be discussed, especially with reference to its efficiency as a filter.