Using laser light as X-rays

["Sandy Perle" <sandyfl@earthlink.net>]

An interesting article. The future perhaps?

PASADENA, Calif., March 13 (UPI) -- Researchers have one up on 
Superman, at least in seeing through objects.

The scientists have succeeded in using laser light to see through 
things, including human tissue. They say potential applications of 
the new technology could include medical situations in which X-rays
are ineffective or downright dangerous.

A team led by chemist Seth Marder of the California Institute of 
Technology and a group from the University of Arizona have developed 
a photorefractive polymer that is highly sensitive to near infrared 
light.

Polymers are large, chain-like molecules formed by chemical binding 
of smaller molecules. An example of a natural polymer would be cotton 
or rubber while synethtic polymers include nylon and polyethylene. 
Polymers are used to make a variety of materials -- from clothing to 
electronics.

Using the new photorefractive polymer they custom-designed for a 
state-of-the-art laser holography setup, the scientists are able to 
see through about half an inch of 2 percent milk.

Marder says the work capitalizes on the fact that certain low-energy 
wavelengths can penetrate solid substances to a certain extent. 
Visible light, radio and TV waves, infrared heat from an oven, and 
X-rays are all manifestations of electromagnetic radiation that 
differ only in wavelength and energy.

Says Marder: ``If you hold your hand up to a bright light source with 
your fingers closed tightly, you can actually see light coming 
through the skin itself. In your body there are various things that
absorb light such as amino acids, DNA, hemoglobin -- which means you 
can't see through them with ultraviolet or visible light.''

But given a low enough energy, many of these tissues stop absorbing 
light.

Marder explains, ``It turns out that, in the near infrared, your body 
is relatively transparent.''

The new research aims at analyzing the light that has penetrated 
tissue.

Led by Bernard Kippelen and Nasser Peyghambarian, the Arizona team is 
using extremely fast lasers to look only at photons of light referred 
to as ``ballistic photons'' while filtering out scattered photons 
that arrive an instant later. By filtering out the scattered photons, 
it is possible to recapture the original image.

Marder cautions the technique is rudimentary and even in its final 
form may not see through nearly as much tissue as X-rays. But, he 
points out, the aim is not to replace X-rays in all applications 
-- just the ones where laser light would be more effective and safer, 
such as in examining delicate eye tissue.
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Sandy Perle
Technical Director
ICN Dosimetry Division
Costa Mesa, CA 92626
Office: (800) 548-5100 x2306 
Fax:    (714) 668-3149
  
sandyfl@earthlink.net
sperle@icnpharm.com

Personal Website: http://www.geocities.com/CapeCanaveral/1205
        
ICN Dosimetry Website: http://www.dosimetry.com

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