Windows and Filters

doi:10.1117/3.176482.ch11

Windows and Filters

Book: Soft X-Ray Optics

Author(s): Eberhard Adolf Spiller

Published: 1994

https://doi.org/10.1117/3.176482.ch11

Author Affiliations +

Abstract

Due to the high absorption of all materials in the XUV region all windows and filters have to be thin membranes with thicknesses in the 0.1- to 10-Î¼m range. We see from Fig. 2.5 that Be, C, Al, and Mg have low absorption coefficients. However, a material which can be made thinner might give higher transmission, even if it has a larger absorption coefficient. The art of fabricating such thin membranes has evolved over the last 30 years and has been reviewed [1â3]. Several suppliers can provide standard membranes and are able to provide customized structures [4â6]. The main function of a window is to separate two environments but transmit the desired radiation. Examples are: - Protect the ultrahigh vacuum of a synchrotron source from the vacuum or atmosphere in the instrument of a user; - Separate the atmosphere in a flow-proportional counter from the vacuum of the experiment; - Support an absorber pattern in a mask for x-ray lithography; - Protect an experiment from the debris of a laser plasma x-ray source. Windows should have the highest possible transmission for the desired radiation. However, because all materials have absorption, and the absorption changes with wavelengths, each window will also have a filter function. It will transmit some wavelengths more than others.