Flux Monitoring on an X-Ray Refractive Diamond Lens

Synchrotron-based science has had a great scientific impact and will continue to have great impact going forward. In spite of the large investment in the 3rd generation light sources, most beam lines do not preserve the source’s phase profile or brightness all the way to the sample. For these high brightness light sources, errors are almost completely due to distortion in the front-end optics caused by the high heat loads generated by the broadband radiation from the insertion device. The role of the first optic is to reduce the heat load on the rest of the beam line by reducing the bandwidth of radiation transmitted downstream. Diamond is rapidly gaining acceptance as an optical material for 3rd and 4th generation light sources because of its superior thermal properties. Existing applications include vacuum windows, attenuators, phase plates and monochromator crystals. These applications take advantage of diamond’s low coefficient of thermal expansion, low absorption and high thermal conductivity which combine to minimize distortion under thermal load. Beryllium is the only other practical material with better absorption properties but its health and environmental concerns make diamond a preferred choice. Delaware Diamond Knives has produced several prototype refractive lens from single crystal diamond whose performance approaches that of today’s commercially available optics. We intend to test innovative cutting processes to further improve the diamond lens performance. In addition, we will use diamond’s electronic properties to add a flux monitoring capability to the lens to simplify and make safer the setup and operation of experiments. Finally, we will test a lens assembly in the X13B line at BNL. Success will motivate us to work toward standardization of lens and mounting products for both white and polychromatic beams. The proposed approach has the potential for a significant impact on materials research at synchrotron facilities around the world. It solves an immediate and pressing problem of spatial resolution for them creating additional opportunities for micro- and nano-scale research for users of 3rd and 4th generation light sources.