Microscope with 50-nanometre resolution demonstrated - BBC News

Discussion in 'Digital SLR' started by Bruce, Mar 1, 2011.

  1. Bruce

    Bruce Guest



    UK researchers have demonstrated the highest-resolution optical
    microscope ever - aided by tiny glass beads.

    The microscope imaged objects down to just 50 billionths of a metre to
    yield a never-before-seen, direct glimpse into the "nanoscopic" world.

    The team says the method could even be used to view individual

    Their technique, reported in Nature Communications, makes use of
    "evanescent waves", emitted very near an object and usually lost

    Instead, the beads gather the light and re-focus it, channeling it
    into a standard microscope, allowing researchers to see with their own
    eyes a level of detail that is normally restricted to indirect methods
    such as atomic force microscopy or scanning electron microscopy.

    Using visible light - the kind that we can see - to look at objects of
    this size is, in a sense, breaking light's rules.

    Normally, the smallest object that can be seen is set by a physical
    property known as the diffraction limit.

    Light waves naturally and inevitably "spread out" in such a way as to
    limit the degree to which they can be focused - or, equivalently, the
    size of the object that can be imaged.

    At the surfaces of objects, these evanescent waves are also produced.

    As the name implies, evanescent waves fade quickly with distance. But
    crucially, they are not subject to the diffraction limit - so if they
    can be captured, they hold promise for far higher resolution than
    standard imaging methods can provide.
    Going viral

    "Previously, people inlcuding ourselves have been using microspheres
    for focusing light for fabrication purposes, so we can machine
    features smaller than the diffraction limit," explained Lin Li, of the
    University of Manchester's Laser Processing Research Centre.

    "It just came to my mind that if we reverse it, we might be able to
    see small features as well, so that is the reason we carried out this
    piece of research," he told BBC News.

    Professor Li and his colleagues used glass beads measuring between two
    and nine millionths of a metre across, placed on the surfaces of their

    The beads collect the light transmitted through the samples, gathering
    up the evanescent waves and focusing them in such a way that a
    standard microscope lens could pick them up.

    The team imaged minuscule features in various solid samples and even
    the nanometre-scale grooves in Blu-Ray discs to show that the
    approach's resolution beat all previous records for optical

    But Professor Li thinks the technique holds great promise for
    biological studies, for which the action at the nanoscale is difficult
    to see directly.

    "The area we think will be of interest will be looking at cells,
    bacteria, and even viruses," he said.

    "Using the current technology, it is very time consuming; for example,
    using fluorescence optical micoscopy, it takes two days to prepare one
    sample and the success rate of that preparation is 10 to 20%. That
    illustrates the potential gain by introducing a direct method of
    observing cells."

    Ortwin Hess of Imperial College London said that "it's really quite
    fascinating and exciting to see these effects coming together".

    "If you use the fact that you do generate those (evanescent waves) and
    focus them again, then you have a tight focal point that you wouldn't
    normally expect to have," he told BBC News.

    "It's quite a nice phenomenon that they've absolutely exploited."


    Bruce, Mar 1, 2011
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  2. Bruce

    RichA Guest

    Awesome. They've had different methods to go beyond the diffraction
    limit of visible light optics before, but nothing like that. Be great
    if it was inexpensive. :) Failing that, from time to time, used
    electron microscopes come up for sale for reasonable (few thousand $$)
    RichA, Mar 1, 2011
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  3. Bruce

    gamer_reg Guest


    Fascinating article. Thank you for posting it.
    gamer_reg, Mar 2, 2011
  4. Bruce

    Bruce Guest

    You're welcome. Glad it was of interest.
    Bruce, Mar 2, 2011
  5. Bruce

    Whisky-dave Guest

    I was reading that last night and trying to understand evanescent
    From what I understand this method would work with DSLRs or anything
    unless you're really close to the subject and of course no chance of
    using flash ;-)

    But maybe I've just not understood it properly.
    Whisky-dave, Mar 2, 2011
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