Design of a New Far Ultraviolet Interferometer for Ionospheric Spectroscopy

摘要

A new far ultraviolet interferometer for ionospheric spectroscopy was designedand tested. The design uses a concave spherical grating in an off-plane Rowland circle configuration. Wave fronts are split into zero and negative first order diffractions, reflected by plane mirrors and recombined by the spherical grating to produce interference fringes. Use of a single concave grating reduces the total number of reflections to three for each path. The off-plane configuration was required to obtain equal path lengths. The ruling density was selected to eliminate other diffracted orders. The design was tested first by verifying the feasibility of recombining a divided wave front using two similar flat transmission gratings. Next a concave grating interferometer using a helium neon laser as the source. The design produced a high quality fringe pattern suitable for spectroscopic analysis.