wrote in news:1107218116.856975.93780
@c13g2000cwb.googlegroups.com:

"Pilots"? More than one?

The letter that one of the members on the laser forum, Skywise,
received from the APSA refers to multiple pilots with retinal burns.
Here's the link to his Web page:

http://www.skywise711.com/lasers/APSA.html

"Anyway, I didn't know that there was an alt.laser"

Technically, it's alt.lasers .
so I'll xpost this to there.

So I see.

Thanks for pointing these folks to the right place.

Also, the APSA is not a government organization.

My conversations with the president of the APSA have not
shed any light on the situation.

The claim of retinal damage is still anecdotal.

Laser induced retinal damage is also difficult to diagnose.
It takes an opthamologist with experince in laser injuries
to make a proper diagnosis. So far, all I have been told is
that the diagnosis was made by "a physician."

Also, the descriptions of the symptoms reported are
inconsistent with laser injury. The descriptions I have
heard are more consistent with temporary irritation of the
cornea or outer eye and eyelids due to excessive rubbing
or irritation due to dirt or dust.

My calculations show that in at least one incident where
the aircraft was at 8500 feet that it would take a very
powerful laser to cause eye damage at that distance. The
beam simply spreads out too much, even with collimating
optics.

If such powerful lasers were used, they would have been
easily seen by witnesses on the ground. When I asked about
such witnesses, none are known. So either the beam was not
so powerful or there just didn't happen to be anybody
looking at the time.

Then there is the difficulty in tracking the aircraft. In
one incident it is claimed the laser tracked the aircraft
for 15-20 seconds. I own a telescope and I have many times
tried manually tracking a plane to watch it through the
scope. It's difficult at best. The higher the aircraft is
the easier it is due to the slower apparent motion. But the
higher the plane is, the more powerful the laser needs to
be to cause retinal damage.

The only thing that is certain and is indisputible is that
even a small laser can potentially be a hazard to aircraft
operations at critical times such as final approach.

My efforts are currently concentrating on the alleged
retinal damage.

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy

Home of the Seismic FAQ
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