Tin-polyimide and indium-polyimide thin-film composites as soft x-ray bandpass filters

A tin-polyimide and an indium-polyimide soft x-ray bandpass filter were fabricated with thicknesses of 1400 and 1750 A for the metal and polyimide components, respectively. The transmission of each filter was measured at the Stanford Synchrotron Radiation Laboratory. The transmission of the tin-polyimide filter was found to be ~40% for radiation with wavelengths between 60 and 80 A. The transmission of the indium-polyimide filter was greater than 40% between 70 and 90 A. The indium was ~5% more transmissive than the tin and attained a maximum transmission of ~48% at 76 A. Such filters have potential applications to soft x-ray telescopes that operate in this region. They might also be of interest to investigators who work with x-ray microscopes that image live biological specimens in the 23-44-A water window.