Abstract Details
| New Approaches in CDI: Diverging and Partially Coherent Beams | |
|---|---|
| Abstract ID | W_Coherent-5 |
| Presenter | Garth Williams |
| Presentation Type | Coherent X-ray - LCLS |
| Full Author List | G. J. Williams (1) |
| Affiliations | (1) University of Melbourne |
| Category | Instrumentation/Development |
| Abstract | The development of coherent diffractive imaging (CDI) has found its impetus in X-ray microscopy by providing sample characterization without the resolution limitation or inefficiency of nanofabricated lenses. CDI achieves this by foregoing an image forming lens; in lieu, employing the well-known laws of the propagation of light and a uniqueness relationship between an object of finite support and its autocorrelation function.
Fresnel CDI employs a beam conditioning lens, providing a two-fold advantage at the detector: the removal of translational invariance eliminates many of the ambiguous solutions inherent in the plane-wave variant and beamstops are obviated by the diverging beam illuminating the sample spreading over many detector pixels. Further, the beam can be used to form an effective sample, so that the finite support constraint can be imposed on nearly any object by a simple alteration of the experimental geometry. The results of applying Fresnel CDI to biological and technological samples will be presented and the implications of XFEL sources explored. Fresnel CDI is made successful through careful attention to beam characteristics. Recently, we have taken this idea one step further by extending CDI to allow for the imperfect coherence of the source. We will present experimental results utilizing a source with measured, non-trivial longitudinal coherence and simulations of the successful reconstruction of a sample illuminated by a beam possessing poor lateral coherence. These techniques may be of great importance in optimizing CDI reconstructions with XFELs. |
| Footnotes | |
| Funding Acknowledgement | |