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Sheffield Scientists Have Revolutionized the Electron Microscope
An anonymous reader writes "For over 70 years, transmission electron microscopy (TEM), which 'looks through' an object to see atomic features within it, has been constrained by the relatively poor lenses which are used to form the image. The new method, called electron ptychography, dispenses with the lens and instead forms the image by reconstructing the scattered electron-waves after they have passed through the sample using computers. Scientists involved in the scheme 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."
from TFA:
The new method, called electron ptychography, dispenses with the lens and instead forms the image by reconstructing the scattered electron-waves after they have passed through the sample using computers.
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.
I call it BS, there is no other way to measure phase than by interference. It seems they just reinvented holography indeed!
No really. In SAR processing you need to know the phase of the signal. The important part here is they do it without phase information. The article doesn't explain how they reduce the ambiguity.
http://www.nature.com/ncomms/journal/v3/n3/full/ncomms1733.html
The actual article is open access: http://www.nature.com/ncomms/journal/v3/n3/full/ncomms1733.html
The article implies that the method is new, which is not the case - in fact it even has its wikipedia page (http://en.wikipedia.org/wiki/Ptychography). The team (J. Rodenburg's) behind that press release is indeed among the pioneers.
The whole idea behind the technique is to illuminate the sample at different positions using an electron or X-ray beam, with an overlap between the different positions of the beam. Once this is done the algorithm reconstructs both the structure in the sample (the electronic density) and the structure of the probe (the electron or X-ray beam).
For those who can access articles behind paywalls :
[1] W. Hoppe, Ultramicroscopy 10 (1982) 187–198. http://dx.doi.org/10.1016/0304-3991(82)90038-9
[2] B.C. McCallum, J.M. Rodenburg, Ultramicroscopy 52 (1993) 85–99. http://dx.doi.org/10.1016/0304-3991(93)90024-R
[3] P.D. Nellist, B.C. McCallum, J.M. Rodenburg, Nature 374 (1995) 630–632. http://dx.doi.org/10.1038/374630a0
[4] P.D. Nellist, J.M. Rodenburg, Acta Crystallogr A Found Crystallogr 54 (1998) 49–60. http://dx.doi.org/10.1107/S0108767397010490
[5] T. Plamann, J.M. Rodenburg, Acta Crystallogr A Found Crystallogr 54 (1998) 61–73. http://dx.doi.org/10.1107/S0108767397010507
[6] J.M. Rodenburg, H.M.L. Faulkner, Appl. Phys. Lett. 85 (2004) 4795. http://dx.doi.org/http://link.aip.org/link/APPLAB/v85/i20/p4795/s1&Agg=doi
It's also used with X-rays (the last article is open access) :
[1] J.M. Rodenburg, A.C. Hurst, A.G. Cullis, B.R. Dobson, F. Pfeiffer, O. Bunk, C. David, K. Jefimovs, I. Johnson, Phys. Rev. Lett. 98 (2007) 034801. http://dx.doi.org/10.1103/PhysRevLett.98.034801
[2] P. Thibault, M. Dierolf, A. Menzel, O. Bunk, C. David, F. Pfeiffer, Science 321 (2008) 379–382. http://dx.doi.org/10.1126/science.1158573
[3] M. Dierolf, A. Menzel, P. Thibault, P. Schneider, C.M. Kewish, R. Wepf, O. Bunk, F. Pfeiffer, Nature 467 (2010) 436–439. http://dx.doi.org/10.1038/nature09419
[4] C.M. Kewish, P. Thibault, M. Dierolf, O. Bunk, A. Menzel, J. Vila-Comamala, K. Jefimovs, F. Pfeiffer, New J. Phys. 110 (2010) 325–329. http://dx.doi.org/10.1016/j.ultramic.2010.01.004
The Sheffield that's pronounced "sheffield" is actually in Yorkshire, pronounced "yorkshire", which is where this research took place.
The Sheffield you're thinking of is the one that's pronounced "glasgow", and even there, you're more likely to run into Scots (a dialect of English, ye ken) than Scottish Gaelic, which is more of a highland thing.
2*3*3*3*3*11*251
The phrase "no fundamental experimental boundaries" is in contrast to (in the actual paper) "However, to date all implementations of this approach have suffered from various experimental restrictions." The summary (and the article it summarizes) take it slightly out of context.