Kinoform Optics Applied to X-ray Photon Correlation Spectroscopy
ORAL
Abstract
Moderate de-magnification, higher order silicon kinoform focusing lenses have been fabricated via e-beam lithography and deep etching to facilitate small-angle hard-x-ray photon correlation spectroscopy (XPCS) experiments. Typical lenses have focal lengths of one meter, focus in the vertical direction to within 80{\%} of the diffraction limit and have vertical acceptance apertures of 400 microns. The acceptance in the orthogonal (etch) direction is 50 microns. The measured efficiency of the lenses is 35{\%} and the flux gain at the focal line is 50. We discuss the effect of focusing on the resulting x-ray speckles. We conclude that one-dimensional vertical x-ray focusing via present-generation silicon kinoform lenses increases the usable coherent flux from third-generation storage-ring light sources for small-angle XPCS experiments by a factor of 3. We also discuss the prospects for further improvements in efficiency via diamond or lower order silicon kinoform lenses.
*Research carried out in part at the CFN and APS, Brookhaven and Argonne National Laboratories, respectively, which are supported by the U.S. DOE, Office of Basic Energy Sciences, under Contract Nos. DE-AC02-98CH10886 and DE-AC02-06CH11357, respectively.
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