Shaped pulses could make opaque film see-through

LONDON - 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.

The team has reported that it took about 10 minutes of repetition for the system to refine the tweaks sufficiently to create a coherent, bright pulse that was still just 115 femtoseconds long despite its tortuous route through the paint.

By modifying the light pulse to travel through skin instead of paint it might be possible to deliver short, intense laser pulses to destroy cancer cells but leave nearby healthy cells intact.

The findings appeared in the journal Physical Review Letters. (ANI)