Synthetic incoherence for electron microscopy.
Tomographic studies of submicrometer samples in materials science using electron microscopy have been inhibited by diffraction effects. In the present work, we describe a practical method for ameliorating these effects. First, we find an analytic expression for the mutual coherence function for hollow-cone illumination. Then, we use this analytic expression to propose a Gaussian weighting of hollow-cone illumination, which we name tapered solid-cone illumination, and present an analytic expression for its mutual coherence function. Finally, we investigate numerically an n-ring approximation to tapered solid-cone illumination. The results suggest a method for removing diffraction effects and hence enabling tomography.
Levine
Zachary H
ZH
National Institute of Standards and Technolgy, Gaithersburg, Maryland 20899-8410, USA. zlevine@nist.gov
Dunstan
Robyn M
RM