Abstract
For hard xâray transmission microscopy at photon energies higher than 15 keV we design refractive condenser and imaging elements to be used with synchrotron light sources as well as with xâray tube sources. The condenser lenses are optimized for low xâray attenuationâresulting in apertures greater than 1 mmâand homogeneous intensity distribution on the detector plane, whereas the imaging enables highâresolution (<100 nm) fullâfield imaging. To obtain high image quality at reasonable exposure times, customâtailored matched pairs of condenser and imaging lenses are being developed. The imaging lenses (compound refractive lenses, CRLs) are made of SUâ8 negative resist by deep xâray lithography. SUâ8 shows high radiation stability. The fabrication technique enables highâquality lens structures regarding surface roughness and arrangement precision with arbitrary 2D geometry. To provide point foci, crossed pairs of lenses are used. Condenser lenses have been made utilizing deep xâray lithographic patterning of thick SUâ8 layers, too, whereas in this case, the aperture is limited due to process restrictions. Thus, in terms of large apertures, condenser lenses made of structured and rolled polyimide film are more attractive. Both condenser types, xâray mosaic lenses and rolled xâray prism lenses (RXPLs), are considered to be implemented into a microscope setup. The xâray optical elements mentioned above are characterized with synchrotron radiation and xâray laboratory sources, respectively.
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