Refractive x-ray lenses have been fabricated using deep x-ray lithography. Lenses were produced directly in 1-to 6-mm-thick sheets of polymethylmethacrylate (PMMA) with as many as 100 cylindrical lenses along the optical axis. The fabrication process consists of exposing the PMMA sheets to highenergy synchrotron radiation through a mask of 50-micron-thick gold on silicon and subsequent development in ketone. The lenses are suitable for use in synchrotron radiation from a bending magnet at the

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... vanced Photon Source in the energy range of 8-16 keV. Results of measurements of focus quality, flux density gain, and scatter are presented and discussed with regard to the quality of lens material and fabrication method. Means for improving the performance of the lenses is discussed.