Soft X-ray transmission of optical blocking filters for the X-ray CCD cameras onboard Astro-E 2

We measured soft X-ray transmission of Optical Blocking Filters for Charge Coupled Device cameras, which will be launched as focal plane detectors of X-ray telescopes onboard the Japanese fifth X-ray astronomical satellite, Astro-E 2. The filters were made from polyimide coated with Al. The X-ray absorption fine structures at the K edges of C, N, O and Al were measured. The depth of the absorption edge of O was deep, compared to the other elements of polyimide. This is the evidence of the oxidation of Al.