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Friday, March 4, 2011

Microscope with 50-nanometre resolution

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 viruses.
Their technique, reported in Nature Communications, makes use of "evanescent waves", emitted very near an object and usually lost altogether.
Instead, the beads gather the light and re-focus it, channelling it into a standard microscope.
This allowed 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.

Some of these indirect methods have imaged to a resolution of one billionth of a metre (nanometre), and even given a glimpse of a single molecule - but none is the same as simply looking down a microscope directly at details this tiny.
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.
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