Silicon Fresnel zone plates for high heat load X-ray microscopy

A technique to produce diffractive X-ray lenses optimized for high heat load applications is demonstrated. The lenses are made from single crystal silicon membranes, which have uniform thermal conductivity and homogeneous thermal expansion. Silicon Fresnel zone plates with an outermost zone width down to 30 nm were produced by means of electron beam lithography and reactive ion etching. They were tested in conventional synchrotron light sources in a full-field transmission X-ray microscope and ill a scanning transmission X-ray microscope. Features below 35 nm were resolved. High resolution in combination with ability to withstand high heat load radiation make them a potential candidate for the new generation of X-ray sources based on the free electron laser principle. (C) 2008 Elsevier B.V. All rights reserved.