Tuesday, March 9, 2010

Technique Allows Scientists to Peer Through Opaque Materials

Filed under: in the news...

Researchers at the City of Paris Industrial Physics and Chemistry Higher Educational Institution (ESPCI) have shown that opaque substances can actually be viewed through, and can be made to perform like optical lenses, using laser light and a bit of mathematics. The technology may allow viewing of cells and other biological components through tissue that would otherwise shield them.

In order to demonstrate their approach to characterize opaque substances, the researchers first passed light through a layer of zinc oxide, which is a common component of white paints. By studying the way the light beam changed as it encountered the material, they were able to produce a numerical model called a transmission matrix, which included over 65,000 numbers describing the way that the zinc oxide layer affected light. They could then use the matrix to tailor a beam of light specifically to pass through the layer and focus on the other side. Alternatively, they could measure light emerging from the opaque material, and use the matrix to assemble of an image of an object behind it.

In effect, the experiment shows that an opaque material could serve as a high quality optical element comparable to a conventional lens, once a sufficiently detailed transmission matrix is constructed.

Abstract in Physical Review Letters: Measuring the Transmission Matrix in Optics: An Approach to the Study and Control of Light Propagation in Disordered Media

Viewpoint in APS Physics: The information age in optics: Measuring the transmission matrix

More: Physicsists find a way to see through paint, paper, and other opaque materials ...

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replies: 1 comments
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This work is similar to work done back in 2008 regarding deterministic scattering of biological tissue (NIH paper: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2688902/pdf/nihms-111267.pdf).

However, physics is physics; while you may be able to take the light which makes its way through the medium and back out the scattering which occurred along its path in order to reimage the light, that does not mean it could be considered a "high quality optical element comparable to a conventional lens".

Depending on the material, only a small fraction of the light will scatter through the material to be transmitted, the rest will either be reflected back to the source, or absorbed by the material, all of which will be wavelength dependent. While this technology may be useful in correcting aberrations in an optical system, or be implement in a system described here: (http://www.opticsinfobase.org/abstract.cfm?uri=BIOMED-2008-BSuE32), there is no way one could make an optic out of a sponge.


Posted by: Smitty McSmith
on March 9, 2010 11:41 AM GMT

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