Ptychography TEM forms an image from scattered electron waves
Baku, March 29 (AZERTAC). The University of Sheffield, England, announces that researchers have developed a transmission electron microscope (TEM) based on electron ptychography, in which an image is formed when a computer reconstructs scattered electron waves after they have passed through the specimen. According to project leader Professor John Rodenburg, "We´ve shown we can improve upon the resolution limit of an electron lens by a factor of five. An extension of the same method should reach the highest resolution transmission image ever obtained; about one tenth of an atomic diameter. No longer does TEM have to be bound by the paradigm of the lens, its Achilles´ heel since its invention in 1933.
"Scientists consider their findings to be a `first step´ in a `completely new epoch of electron imaging´. The process has no fundamental experimental boundaries and it is thought it will transform sub-atomic scale transmission imaging.
Professor Rodenburg added: "We measure diffraction patterns rather than images. What we record is equivalent to the strength of the electron, X-ray or light waves which have been scattered by the object - this is called their intensity. However, to make an image, we need to know when the peaks and troughs of the waves arrive at the detector - this is called their phase.
"The key breakthrough has been to develop a way to calculate the phase of the waves from their intensity alone. Once we have this, we can work out backwards what the waves were scattered from: that is, we can form an aberration-free image of the object, which is much better than can be achieved with a normal lens. A typical electron or X-ray microscope image is about one hundred times more blurred than the theoretical limit defined by the wavelength. In this project, the eventual aim is to get the best-ever pictures of individual atoms in any structure seen within a three-dimensional object."
The ground-breaking results were part of a three-year study costing £4.3 million which was funded by the Engineering and Physical Sciences Research Council (EPSRC).
Ptychographic electron microscopy using high-angle dark-field scattering for sub-nanometer resolution imaging was published in Nature Communications on Tuesday 6 March 2012.
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