Aberration corrected echelle spectrographs for the far ultraviolet

Abstract

Ultraviolet spectroscopy is a key element in the multi-wavelength approach to astronomy. Echelle spectroscopy provides high resolution and broad wavelength coverage and is a frequent choice for optical spectroscopy. However, it has limitations when applied to ultraviolet applications, particularly in the far ultraviolet, at wavelengths shortward of the MgF2 cutoff at ~ 1150 Å. I present an approach to provide echelle spectroscopy at these short wavelengths, enabling aberration control with only two optics post-telescope, by using gratings with curved and variable line-space grooves.