Sunday, February 27, 2011

Shaped pulses could make opaque film see-through


A non-invasive technique for targeting cancer cells may soon become a reality, thanks to researchers who have found a new way of providing crystal clear vision through an opaque layer.


Some opaque materials allow small amounts of light through if they are in a thin enough layer. But as light passes through the layer it is scattered in both time and space, so an image projected on one side emerges blurry and unfocused on the other.


Now, scientists have discovered a way to sharpen things up, reports New Scientist.


Jochen Aulbach at the FOM Institute for Atomic and Molecular Physics in Amsterdam, the Netherlands, and colleagues figured that it should be possible to manipulate light so that the scattering it experiences as it passes through the layer leaves it focused.


They used a liquid crystal device, which allows precise control of light, called a spatial light modulator (SLM), to manipulate 64-femtosecond-long laser pulses being projected onto a layer of paint.


A detector measured the intensity and duration of the pulses that emerged from the other side. This information was then passed to a computer program that used it to tweak the SLM to make the next pulse arriving at the detector both brighter and less spread out in time.



View the original article here

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