Experimental characterization of zone plates for x-ray microscopy

Abstract

High resolution microzone plates for x-ray microscopy with an outermost zone width down to 30 nm have been used and characterized in the Gottingen x-ray microscope (XM) at BESSY in Berlin. The microzone plates were fabricated through a collaboration between the IBM Watson Research Center and the Lawrence Berkeley Laboratory using an electron beam writing method. The condenser zone plates of the XM were fabricated at the Institute for X-Ray Physics using a holographic method. The microzone plates allow x-ray microscopy with very high resolution. The optical performance of the microscope with these microzone plates has been studied by several methods, which use a special test pattern. The experiments have been performed at x-ray wavelengths of 2.4 nm and 4.5 nm. The results are shown as modulation transfer functions, edge response functions, and line spread functions. All these methods give similar results. Although the system is not diffraction-limited, features down to 30 nm size are visible in the images.