Novel high resolution x-ray methods which are based on the availability of
coherent or partially coherent x-ray light are currently under rapid
development to image biological samples at the nanoscale. We compare two
alternative approaches, based (A) on far-field diffraction and (B) on free
space propagation of a coherent wave, considering image formation and object
reconstruction, illustrated with recent examples [1-4]. We sketch out, how
biomolecular samples and cells can be imaged by the highly divergent and
coherent x-ray beam exiting an x-ray waveguide and/or KB mirror system,
creating a magnified phase contrast projection image and/or hologram of the
sample. We show by scaling arguments (on blackboard) and by experimental
results (ppt slides) that a 5nm lipid membrane illuminated tangentiallyin
water can be imaged by propagation imaging using a highly curved wave front
(A. Beerlink et al., unpublished).
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