Ion track filters in imaging X-ray astronomy

The application of ion track filters as blocking cut-off filters for solar telescopes in imaging X-ray astronomy is presented. Ion track membranes (ITMs) of high-porosity constitute a randomly inhomogeneous medium with sub-micrometer or micrometer open pores which not only transmits X-ray or extreme ultra violet (EUV) radiation and blocks long-wavelength UV radiation, but also transfers a focused imaging pattern with high-quality for further registration by means of CCD or imaging detectors of other types. X-ray and EUV filters based on ITMs with cylindrical parallel pores were successfully used as detector filters in the solar X-ray telescopes designed and manufactured at the Lebedev Physical Institute of the Russian Academy of Sciences (LPI, Moscow).