The Soft X-ray Imager (SXI) – one of the detectors on-board Astro-H – makes use of CCD cameras very much like those used in digital cameras. In order to block visible light impinging on the CCD’s, each detector has an ultra-thin layer of aluminum 0.001 mm thick placed on its surface. Normal aluminum foil has a thickness of about 0.1 mm, so that the Astro-H foils have 1/100th of their thickness! Measuring the precise thickness of this aluminum on the CCD surface is very difficult. Accordingly, the SXI team carried out experiments at a high-energy accelerator facility, exposing the CCD detectors to soft X-rays, in order to measure the thickness of the membrane. Members of Kogakuin University, Osaka University and Rikkyo University all took part in the experiments, and they successfully established the thickness of the membrane formed on the CCD. Everyone looks happy!