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 Angstroms 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 approximately 40% for radiation with wavelengths between 60 and 80 Angstroms. The transmission of the indium-polyimide filter was greater than 40% between 70 and 90 Angstroms. The indium was approximately 5% more transmissive than the tin and attained a maximum transmission of approximately 48% at 76 Angstroms. 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-Angstroms water window.