Morgan BellLaser beam made to curve without loss
December 26th 2007 18:21
A fascinating result published in influential journal Physical Review Letters: Christodoulides et. al. have experimentally created a laser beam that was theoretically proposed 30 years ago.
It's a beam called the Airy beam, and it's interesting because of two important phenomena.
Normally, laser beams spread out over distances. Try it with your laser pointer; in your room, the beam appears tight, but see what happens over the length of the neighborhood block.
The other thing a laser beam does is: travel in a straight line.
Well, Christodoulides et. al. have created a laser beam that doesn't do either of these things. It doesn't spread out over distance, which is a phenomenal effect, but, strangely, the beam curves off to the side.
How did they make this magical laser beam? Easy:
Sounds complicated, I know. To simplify, it would seem that a normal laser is sent through something similar to an LCD computer screen, where the experimenters programmed each pixel to create the proper shape of the beam.
Brilliant, eh?
* this image is from the APS website
It's a beam called the Airy beam, and it's interesting because of two important phenomena.
Normally, laser beams spread out over distances. Try it with your laser pointer; in your room, the beam appears tight, but see what happens over the length of the neighborhood block.
The other thing a laser beam does is: travel in a straight line.
Well, Christodoulides et. al. have created a laser beam that doesn't do either of these things. It doesn't spread out over distance, which is a phenomenal effect, but, strangely, the beam curves off to the side.
"To make the beam, the researchers directed a centimeter-wide laser beam onto a watch-sized liquid crystal display screen called a spatial light modulator (SLM). The reflectivity of each pixel on this screen is related to its index of refraction, so the device allows control of the precise phase of light reflected from each spot. The team programmed the SLM pixels to provide the phase relationships needed for an Airy beam."
Brilliant, eh?
* this image is from the APS website
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Comment by Arun On Technology
Comment by Mountain Fog
It is already frustrating without that happening, in my view, poor dial up drone that I am!!
And next the US army will use it to blind enemy around corners!
cheers Cib, have a good New Year too!
fog