Very high sensitivity extreme ultraviolet spectrometer for diffuse radiation

A compact instrument to measure the diffuse extreme ultraviolet background with unprecedented resolution and high sensitivity is described. The instrument can cover a bandpass from 350 to 1100 Angstrom, has similar to 5 Angstrom spectral resolution, and has simultaneous field imaging with similar to 5' resolution. Several new techniques were employed to achieve this performance, including the development of a unique, fast optical system optimized for diffuse spectroscopy, a novel low-noise microchannel plate photon detector, a mechanism that permits an accurate determination of all the expected backgrounds, and an electronic system with active baseline restoration and coordinate digitization that is free of differential nonlinearity. This instrument will provide a factor of 1000 increase in sensitivity over existing measurements with reasonable observing times.