Re: Lasers To Signal Airspace Breaches

On Sat, 16 Apr 2005 17:47:03 -0700, David <moravianus1@xxxxxxxxx>
wrote:

>http://beta.news.yahoo.com/s/washpost/20050416/ts_washpost/a57641_2005apr15&printer=1
>
>So the cat is out of the bag.
>
>"The U.S. military will begin using an elaborate network of cameras and
>lasers next month to scan the sky over Washington and flash colored
>warning beams at aircraft that enter the nation's most restricted
>metropolitan airspace."
>...
>"Unlike pointers [sic!]and other eye-damaging lasers that have raised
>safety concerns among pilots, the military's beams are low-intensity and
>safe enough for the eyes yet distinctive enough to alert pilots that
>something's wrong, officials say."
>...
>"Researchers who developed the technology say the laser beam is so
>narrowly targeted that other nearby aircraft will not be able to see it.
>Curtis Davis, a researcher at MIT Lincoln Laboratory who helped develop
>the system, said the beam is stronger than a laser pointer, but more
>diffuse. "We've taken the size of the beam and made it 15,000 times
>bigger," Davis said. "It's a foot in diameter."

"Low intensity?" You can barely SEE a laserpointer beam at 1000ft due
to divergence. If I were to estimate the "magnitude" of a red beam
on a white wall at 1000ft from a 5mW laser that has diverged to a
four-foot circle, I'd say it's about mag. 9.
What are they talking about??
-Rich
.

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