Imaging Cells Beyond X-Ray Optics Limits: Status and Possibilities
Chris Jacobsen
Department of Physics and Astronomy, Stony Brook University
X-ray imaging has made rapid advances due to improvements in optics, and coupling with tomography and spectroscopy. However, the resolution of presently-available optics is far from the wavelength limit, and in fact efficiency losses and modulation transfer function rolloffs are very much a part of the picture of present x-ray optics. An alternative approach is to collect the far-field diffraction pattern without any optics losses, and phase the resulting intensities to yield a real-space image. Following initial demonstrations [Miao et al., Nature 400, 342 (1999)] and a number of interesting recent experiments by a variety of groups, we have developed an apparatus [Beetz et al., Nucl. Inst. Meth. A 545, 459 (2005)] able to collect 3D data from frozen hydrated cells. Thus far we have been able to use this to obtain 3D reconstructions on material science specimens [Chapman et al., J. Opt. Soc. Am. A 23, 1179 (2006)] and 2D reconstructions on dried but unstained eukaryotic cells [Shapiro et al., Proc. Nat. Acad. Sci. 102, 43 (15343)]. The promise, limitations, and outstanding issues in this approach to high resolution imaging will be discussed, including the ways in which an energy recovery linac light source could benefit the experiment.
