Large area x-ray collimator-the zone plate approach.

One question of particular interest in the measurement of x-ray imaging optics for space telescopes concerns the characteristics of the point spread function (PSF) in orbit and 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 required. For this purpose a large area transmission x-ray zone plate (ZP) for collimating x-ray beams has been designed, built, and tested.