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We compared the reconstruction performance of six different impedance tomographic reconstruction algorithms in a two-dimensional computer simulation. We found the modified Newton-Raphson method applied to the finite-element method performed the best. We show that this method can also make a better one step correction in less time than any of the other methods.

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Tomographic x-ray holography may make possible the imaging of biological objects at high resolution in three dimensions. We performed a demonstration experiment with soft x-rays to explore the feasibility of this technique. Coherent 3.2-nra undulator radiation was used to record Fourier transform holograms of a microfabdcated test object from various illumination angles. The holograms were numerically reconstructed according to the principles of diffraction tomography, yielding images of the object that are well resolved in three dimensions. I Accordingly, tb_ /. $, Government retains a " _ fft_* _. E_ _ nonexclusive, ru/,,ity-free license to publish _ _o/Lr_ _,_. _FEB or reproduce the published form of this contribution, or allow others to do so, for U. S. Government purposes. DISTRIBUTION OF THIS DOCUMENT iS UNLI lT DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liabilityor responsibility for the accuracy, completeness, or usefulness of any information, apparatus,product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

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This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this prepr_nt is made available with the understa:,dlng that it will not be cited or reproduced without the permission of the aufl_or. eT'ED DISTRIBUTION OF,THIS DOCUMENT ISL_UNLIMITED J lt DISCI.AIMER qb This document was prepared _s an account of work sponsored by an agency of the ,. United States Government. Neither the United States Government nor the University of California nor an)' of their employees, makes any warranty,expressor implied, or assumes an)' legal liahllit._ or responsibility for the accuracy, completeness, or usefulness of an.,,'information, apparatus, product, or process disclosed, or represents that its use would not infrlllge privately owned rights. Reference herein to an)' specific c_mmerclal products, process, or service by trade name, trademark, manufacturer,or otherwise, does not n_cessarily co,lslt_.te or imply its endorsement, recommendation, or favort,lg by the IJntted States Governn,ent or the University of California. The views and opinions of authors expressed herein do not necessar_|y state or reflect those of the I.Jnited States Government or the University of California, and shall not be used for advertising or product endorsement purposes.