Fabrication and testing of hard x-ray sputtered-sliced zone plate

Abstract

A sputtered-sliced hard x-ray zone plate has been made by the physical vapor deposition of alternating transparent and opaque layers onto a fine gold wire core of 50 μm diameter. The zone plate is designed to operate with a focal length of 124 mm at 8.05 eV and consists of 25 pairs of alternating Ag and C layers with a thickness of ∼40 μm along the wire axis. Using monochromized synchrotron x ray with an energy of 8.05 keV the minimum focal spot size attained for the first order focal beam was 2.3 μm in the vertical and horizontal directions, respectively. The light-collecting efficiency was determined to be ∼4%. The focal spot size obtained was substantially larger than the 1.2 μm φ spatial resolution predicted from the contradiction of the light source size.