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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."
Expect all sorts of imaging systems to evolve in this direction over the next few years.
It's more interesting for things like CAT and NMR, IMHO.
The Human League, Def Leppard, Heaven 17, ABC, Cabaret Voltaire and Pulp rejoice!
It doesn't mean much now, it's built for the future.
How do you pronounce "ptychography"??
No. Read TFA (which is s bit short on detail).
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
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.
I call BS on the summary. It says "The process has no fundamental experimental boundaries and it is thought it will transform sub-atomic scale transmission imaging". But TFA actually states "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."
If they're measuring the wave diffraction as it passes through the atomic structure, then the diffraction limit is most definitely a "fundamental...boundary". If the addition of the word "experimental" means that they found no boundaries in their experiments, that just means they haven't gotten to the diffraction limit of the atomic aperture for those wavelengths yet (i.e. we're not even close to the fundamental boundaries, so we'll say our results are not limited in any way in our experiments). Either way, not a great way to talk about the results - too much sensationalism, not enough science.
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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
took me forever to find it, but here is the original article behind the Nature paywall
http://www.nature.com/ncomms/journal/v3/n3/full/ncomms1733.html
the paper feels like it written by the marketing department for his company.
We will be able to see that violin you talk about!!!!
Basically what they have done is phase contrast transmission electron imaging. This is quite an achievement in itself and well done to them. However they most certainly did not invent this "technique" (and I doubt they actually claimed that). The method is well known from X-ray phase contrast imaging research.
They even wrote this: "The technique is applicable to microscopes using any type of wave and has other key advantages over conventional methods. For example, when used with visible light, the new technology forms a type of image that means scientists can see living cells very clearly without the need to stain them, a process which usually kills the cells."
Em, yes but optical phase-contrast is damn well established. O and Frits Zernike who got the Nobel prize for doing exactly this in 1953 might be pissed off.
We want to see your electron clouds
We're so used to ignoring things that look like ads or links to other stories that we fail to notice the images down the column at the right are, in fact, the images we're looking for.
So, are you predicting some sort of coal-mine gap?
And in turn, interference results in intensity differences arranged spatially. Thus, phase calculated from measured intensity.
It is certainly RELATED to holography.
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.
I think the only people who would understand it are folks with PhDs in particle-optical-physics with ten years of post doc experience working in the electron microscope field.
I really hate hearing people say stuff like this. Science isn't magic with scary, unknowable stuff going on behind the curtain. It's *very often* easily understood (car analogies, anyone? Hit me!!!111one :-). The devil's in the details and the details can be subtle, but it's not magic.
SEM bombards stuff with $something (energized particles, radiation, ...) which reflects back onto something that stores that reflected $something. It's the same process as an optical camera, but working at different wavelengths and energies (yes, please do feel free to correct me if I'm talking through my hat in your opinion; I won't be offended, honest).
I'm having a difficult time understanding TFS's "... after they have passed through the sample using computers."
Passed through? Since when!?! Passed through the sample using computers? What? SEM doesn't "pass any energy through" whatever it's sampling.
Are we talking about 3D representations of sample then using computers to $massage sample to death? That might make sense.
People should read more about science and how it's done. It wouldn't be as scary to them if they did.
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There are several types of electron microscopes.
You are talking about Scanning Electron Microscopes (SEM), which do work like optical microscopes, bouncing an electron beam off of the object being imaged.
The summary is talking about Transmission Electron Microscopes (TEM), which pass an electron beam through the object being imaged, and works more like microfilm.
This is transmission electron microscopy (not SEM), where electrons are shot through the sample. It's kind of like a standard light microscope where the light goes through the sample and you see the shadow.
What they're doing is reconstructing an image from diffraction patterns instead of focusing it with a lens. I think it's vaguely similar to interferometry. They can apparently also do it with light microscopes, which has certain advantages. Unfortunately the article mixes up the electron and light microscopy - you don't do TEM on living cells, for example, no matter how fancy an imaging system you have.
I was a field service engineer in the 1980's for an electron microscope company. I read TFA and I have no idea what the hell they are talking about. After an installation of a sufficiently high voltage TEM I used to take atomic resolution images to prove the thing was working. And diffraction imaging is extremely common. The only thing I can think of that this might improve is TEM imaging at low voltages. As the accelerator voltage of the electron beam decreases, the field strength of the electromagnetic lenses needs to be decreased to bring everything into alignment and focus. Because of that, noise has a greater effect on the system which effectively reduces resolution. If this process involves any physical movement or integration of multiple images over time, it will never produce an atomic resolution image.
I'm having a difficult time understanding TFS's "... after they have passed through the sample using computers."
TEM is like an X-ray. You shine the "light" through and look at what comes out the other side. Shine a bright flashlight into your palm and notice that you see the light (filtered to be red) coming out the other side, with shadows for your bones and thick parts.
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