Characterising x-ray optics with a collimated x-ray beam: the zone plate approach

An open question in the measurement of X-ray optics for telescopes in space is what the point spread function (PSF) looks like in orbit and what is the focal length for an infinite source distance. In order to measure such a PSF, a parallel X-ray beam with a diameter of several centimeters to meters is needed. For this purpose it is studied of how to collimate the X-rays using a zone plate. Furthermore, a configuration study is presented to characterize X-ray optics with such a collimated beam at the PANTER X-ray test facility. In particular, estimations for segmented optics for future X-ray missions such as ATHENA+ with a focal length of 10m to 20m are presented.