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Science Technology

Sheffield Scientists Have Revolutionized the Electron Microscope 90

Posted by samzenpus
from the I-can-see-clearly-now dept.
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."
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Sheffield Scientists Have Revolutionized the Electron Microscope

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  • didn't read TFA but did they just reinvent holography? http://en.wikipedia.org/wiki/Holography [wikipedia.org]

    • by Anonymous Coward

      no, they are just are using a synthetic aperture
      http://en.wikipedia.org/wiki/Synthetic_aperture_radar

      • Re: (Score:3, Informative)

        by Anonymous Coward
        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.
        • by cyfer2000 (548592)
          I think TFA meant to say they are going to use phase information, but TFA didn't say how they are going to get phase information.
    • Re: (Score:1, Funny)

      by Anonymous Coward

      Sheffield, yeaaaaah, home to two shit football teams and the greatest condiment known to man, Henderson's Relish [hendersonsrelish.com]

    • No. Read TFA (which is s bit short on detail).

    • Re: (Score:2, Informative)

      by miknix (1047580)

      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!

      • Re:holography? (Score:5, Insightful)

        by deapbluesea (1842210) on Wednesday March 07, 2012 @05:51PM (#39280617)

        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.

        • Re:holography? (Score:5, Informative)

          by suutar (1860506) on Wednesday March 07, 2012 @06:50PM (#39281429)
          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.
      • Wrong! You can infer the phase by measuring the deflection angle due to the phase-shift. Naturally this doesn't work for normal angles of incident but the images are still dramatically improved.
      • by sjames (1099)

        And in turn, interference results in intensity differences arranged spatially. Thus, phase calculated from measured intensity.

        It is certainly RELATED to holography.

      • by ceoyoyo (59147)

        Yes, there is. You can measure the phase directly if the frequency is low enough. But the usual way, certainly with higher frequencies, is interference. Which is exactly what he describes - calculating the phase of the waves from their intensity alone.

        From the article it sounds like they arrange for multiple diffraction images to interfere with each other.

  • The Lytro of TEM (Score:2, Insightful)

    by Anonymous Coward

    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.

    • by symes (835608)

      It's more interesting for things like CAT and NMR, IMHO.

      Tricorders?

    • Electron imaging is only possible in vacuum and delivers massive doses typically to microscopic samples. So I doubt it will replace medical CAT or MRI scans any time soon.
    • by ceoyoyo (59147)

      nMR is already an interferometric process. I'm not sure how you'd use this in a CT scanner, or why.

      • nMR measures the spectrum of RF emitted when nuclei excited into alignment by resonant RF pulses relax out of alignment with an externally applied magnetic field. MRI which is the correct name for the imaging modality measures the pattern of this RF emission. Maybe I am missing something but now exactly is this an interferometric process?

        As to how this IS used in a research CT scanners google "phase-constrast CT". O and you want to do this in future to reduce patient dose or highlight soft-tissue boundar
        • by ceoyoyo (59147)

          You're right, MRI (or nMRI) is nMR (Imaging). But the first poster said nMR and I wasn't feeling pedantic enough to contradict him. I really don't see how you'd use this at all if you weren't imaging.

          In MRI you create an image by manipulating the relative phase of atomic nuclei with net magnetic moments. You measure the resulting interference for a bunch of different relative phases, then Fourier transform to get an image. It's interferometric imaging, except you're manipulating the phase instead of the

          • Okay take your point on the MRI. I'd describe that as phase encoding spatial information rather than interference but I accept your way is just as valid. It's certainly not the most common method in X-ray phase-constrast CT. However this method is used for X-ray CT at synchrotrons.
            • by ceoyoyo (59147)

              I wasn't aware they did interferometric CT at synchrotrons. Cool.

              Phase encoding spatial information, interferometry, different words, but they mean the same thing. You are literally measuring interference, thus interfer-ometry. The only distinction is that in MR you get to manipulate the source, which is a little harder in astronomy.

              About ten years ago there were some quite enthusiastic researchers who were trying to do super-resolution MRI. Some thought it was the best thing since phase encoding, other

              • I have done optical super resolution microscopy myself but have never heard about the MRI equivalent. Then again I don't really know much about MRI research so that's not so surprising and I obviously defer to your knowledge on this. Similarly I have seen synthetic aperture talks but only those done with Ultra sound or telescope based data.

                Interesting now all the very different imaging modalities have vastly different implementation rates for similar techniques. Whilst the method and technology of acquis
                • by ceoyoyo (59147)

                  "Whilst the method and technology of acquisition is responsible for some of this I suspect a lot of it is researchers simply not knowing what is going on in other fields."

                  Yes... but adding to that, I think a lot of researchers are so tied up in their own terminology (like phase encoding spatial information) that they have trouble recognizing the same or similar processes described in other fields. I had never thought of MRI as interferometry until I had to look into it. Now when I teach it to graduate stu

                  • Couldn't agree more on the terminology. Eg phase-shift,interference,diffraction,scattering all used to describe similar things in different fields.
                    Yes I did wonder about double slit experiments (started in Atomic physics) but more so about the pattern's mere existence for single photons. The question of its shape seems trivial by comparison. :-) But thats for another board.
  • by Pope (17780) on Wednesday March 07, 2012 @05:36PM (#39280415)

    The Human League, Def Leppard, Heaven 17, ABC, Cabaret Voltaire and Pulp rejoice!

    • I worked at Batchelors foods with Steve Singleton from ABC before they made it big. He saved me from being beaten up by the resident bully. It's a funny ole' world :-).

      Jeremy.

  • by InsertWittyNameHere (1438813) on Wednesday March 07, 2012 @05:37PM (#39280431)
    How do you pronounce "ptychography"??
  • Not to mention simpler preparation of samples.

    To cap it off, I would expect that electron microscopy just got a whole bunch more accessible.

    Well done - there might be a Nobel in it for you.

    myke

  • The actual article (Score:2, Informative)

    by mgrivich (1015787)
    The actual article is open access: http://www.nature.com/ncomms/journal/v3/n3/full/ncomms1733.html [nature.com]
  • by vincefn (705639) on Wednesday March 07, 2012 @06:01PM (#39280769) Homepage

    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 [doi.org]
    [2] B.C. McCallum, J.M. Rodenburg, Ultramicroscopy 52 (1993) 85–99. http://dx.doi.org/10.1016/0304-3991(93)90024-R [doi.org]
    [3] P.D. Nellist, B.C. McCallum, J.M. Rodenburg, Nature 374 (1995) 630–632. http://dx.doi.org/10.1038/374630a0 [doi.org]
    [4] P.D. Nellist, J.M. Rodenburg, Acta Crystallogr A Found Crystallogr 54 (1998) 49–60. http://dx.doi.org/10.1107/S0108767397010490 [doi.org]
    [5] T. Plamann, J.M. Rodenburg, Acta Crystallogr A Found Crystallogr 54 (1998) 61–73. http://dx.doi.org/10.1107/S0108767397010507 [doi.org]
    [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 [doi.org]

    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 [doi.org]
    [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 [doi.org]
    [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 [doi.org]
    [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 [doi.org]

  • I'll wait for the 2nd or 3rd gen iScan so they can get the bugs worked out before I get one. I can get this from the Genius Bar, right?
  • original article (Score:4, Interesting)

    by vossman77 (300689) on Wednesday March 07, 2012 @06:07PM (#39280847) Homepage

    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 [nature.com]

    the paper feels like it written by the marketing department for his company.

    • by vossman77 (300689)

      After reading the paper, they are definitely doing something novel, but the claims made in the paper far exceed what is being presented. Imaging bacteria cells is considered pretty easy -- show me some atoms.

  • We will be able to see that violin you talk about!!!!

  • by kaspar_silas (1891448) on Wednesday March 07, 2012 @06:18PM (#39280989)
    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.
    • I'll say. I've got optical phase-contrast technology in 4 of the 9 cameras currently in my house.

    • by Anonymous Coward

      Well, this and most comments here seem to show that Slashdotters generally think that they understand something and then dismiss it as trivial (hint: most of the comments here completely missed the point). Ptychography generates images from the coherent scattering pattern of the object, and thus it requires no optics. The achievable resolution is limited not by the quality of the optical components, but by the wavelength of the radiation being used (and the time you are able to spend counting those electron

    • by Anonymous Coward

      O and Frits Zernike who got the Nobel prize for doing exactly this in 1953 might be pissed off.

      I don't think he cares. He died in 1966.

    • by ceoyoyo (59147)

      I don't think it's quite that simple. Their technique uses a type of interferometry to reconstruct the image - the imaging itself is done in the Fourier domain, which is definitely not the case for a phase contrast microscope. They also don't need lenses, also not the case in phase contrast microscopy.

      • It's not a type of interferometry as they don't measure phase-shifts directly. They measure the diffraction pattern and infer the phase-shifts that would result in such an image. Basically measuring the Fraunhofer diffraction pattern and computationally reconstructing a sample that would create such a pattern.

        As such if the sample was a plane normal to the electron beam they would see nothing in this method. The imaging is not done in the Fourier domain thou the reconstruction can be if you prefer. For t
        • by ceoyoyo (59147)

          "It's not a type of interferometry as they don't measure phase-shifts directly."

          Interferometry is traditionally done by looking at interference patterns (which is what a diffraction pattern is). That's why it's called interferometry. It's only quite recently that we've been able to (sort of) measure the phase of light at reasonably high frequencies.

          • That's not true. When a physicist (like me) talks about an interferometer generally we mean a device that can measure phase shift or relative phase by comparing a beam with unknown phase to a separate known phase-shift reference beam.
            See: http://en.wikipedia.org/wiki/Interferometry [wikipedia.org]

            Such interferometers (which normally use a point detector and therefore aren't measuring a pattern) have been about for well over a hundred years
            See: A. Michelson, E. Morley. American Journal of Science: 333–345. (188
            • by ceoyoyo (59147)

              I should have been more clear. There are several different types of interferometry. The one you're referring to measures the relative phase between a reference beam and a beam that's had something done to it (passing through a substance or travelling a different distance). Michelson and Morley, as you point out, is probably the most famous example. They were measuring (or trying to measure) very small differences in the time it took two light beams to travel the same distance, in different directions.

              A

              • Ah okay, I understand what you mean now. However I still think your wrong as whilst you can measure phase of photons in the RF/Microwave domain there is no method of measuring phase directly with optical photons never mind 100keV electrons.

                Indirectly by observing the imaging pattern (like a classic optical fringe pattern) the phase-shift can be done. Thou you might have to manipulate the beams to make the pattern more obvious as in classic interferometers or classic phase-contrast microscopy. Or you can
                • by ceoyoyo (59147)

                  I'm not sure if you think I'm wrong or you think I'm right but misunderstood what I said. I do not think it's possible, at this time, to directly (i.e. without causing two signals to interfere with each other) measure the phase of high frequency waves, EM or electron. IIRC people are starting to talk about doing direct phase measurement (sort of) with infrared. If you do think it's possible, and know of an example, I would be very interested to read about it.

                  The Sheffield people aren't measuring the phas

                  • Okay sorry my mistake I thought you meant a direct phase measurement.

                    IMHO they are exactly doing a classic optic phase-constrast technique. Not exactly the same geometry as in microscopes due to the vastly superior optical beam available. But very similar and identical to the one often used for accelators X-ray CT which is why they reference this research. If you think this is wrong thats fine, I just disagree.
    • Saying you don't need a lens is just wrong. At the very very least you need a lens to focus the beam onto the specimen.

      O and if you actually read the paper you'll see that on the right hand column of page 5 all the current experimental limitations on resolution are listed. That the lens doesn't feature doesn't mean it follows that it is just down to wavelength, it's not. There is no lens in any hospital X-ray systems and your 100 keV diagnostic X-rays does not give you ~0.01nm resolution images. There is
  • We want to see your electron clouds

  • Of course, who wouldn't? Looks like a lot of fun, not to mention we might have some scientists in some fields make some discoveries. If we have any scientists, do we still do that or did we outsource?

  • "...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"

    So while the old way had the electrons go through a "lens", they now go through a "computer."

    I have this vision in my head of people looking through PC chassis and hoping to use it in place of a lens. So, what type
  • 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 electromagnet
    • by t4ng* (1092951)
      Ah! Read the article on Nature.... That's exactly what they are doing. They are trying to get atomic resolution images at 30KeV, which is pretty amazing. Back when I worked on TEMs, you needed a minimum of 400KeV to get a decent atomic resolution image.
  • Given electron microscopes are already used for data recovery of mission critical hard drives, it makes me wonder if this discovery has any effect on DOD drive wiping standards.

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