Calibration of the Thin Film Filters to be Used on the Extreme Ultraviolet Explorer Satellite

The methods of calibrating the filters used on the Extreme Ultraviolet Explorer (EUVE) astronomical satellite are described. EUVE will conduct the first all-sky survey in the entire EUV band (68Å-912Å). The filters determine 4 spectral bands in the survey telescopes and act as order filters in the spectrometer telescope. The four flight filter types used are: Lexan/Boron, Aluminum/Carbon, Indium/Tin, and Titanium/Antimony. The measurement of the filters' transmission properties from the soft x-ray to the far UV using a grazing incidence monochromator is discussed. Three radiation sources are used: a hollow cathode discharge source, a continuous discharge Penning source, and a Henke type target x-ray tube. A particle ingress test to determine the ability of the filters to inhibit energetic particles in earth orbit from entering the detector and increasing the background is described. Other filter tests include lifetesting in different storage and operating environments to measure the filters' transmission stability. Problems encountered in calibrating these four filter types are also presented.