I'm going to "Laser" a pilot.

On Sat, 29 Jan 2005 03:56:23 GMT, "Casey Wilson" N2310D @ gmail.com
wrote in HPDKd.2876$RI.2060@trnddc06::


"Larry Dighera" wrote in message
.. .

Big Snip!!


What magnitude of laser power would you estimate to be required to
cause retinal damage at say 1 mile for what period of time?

If I may change to a different laser wavelength with a conforming
lens, a 1 megawatt laser will cause nearly instantaneous, and irreversible,
damage at ranges beyond one mile.

So you figure that 1-megawatt is the MINIMUM power necessary? Given
the fact that the majority of homes in the US are served by a
24-kilowatt (2.4% of a megawatt) electrical service, it's not likely
that any retinal damage is possible without browing out half a
neighborhood. :-)

In article ,
Larry Dighera wrote:


What magnitude of laser power would you estimate to be required to
cause retinal damage at say 1 mile for what period of time?

The problem is not damage, it's "dazzle" -- having what seems to be a
_very_ bright light more or less in the center of your field of view and
coming straight into your eyes.

Yes, you blink, or look away -- but after you open your eyes the bright
incoming light may still be there, very close in angle or position to
the terrain or the instruments you have to look at, so you can't really
easily block it. Even with the laser positioned somewhat off to the
side there may be a lot of bright scatter from dirt or scratches on the
windshield, very similar to the situation of driving a car with a dirty
or scratched windshield (or just with aging eyeballs) looking into the
bright headlights of oncoming cars. And, any night vision adaptation
you may have had is gone (night vision can be wiped out considerably
faster than it can be restored).

All of these effects can be produced at light intensities way, way below
the level that produces any permanent damage to the retina. Though I'm
no expert on this subject, I have also been told that sustained exposure
to this kind of illumination in a situation where you can't just "turn
it off" and where the light levels, although below permanent damage, are
well above what leads to you to blink, and especially if they occur in
stressful situations with demanding performance requirements, can
rapidly lead to various kinds of psychological distress.

"AES" wrote in message

Yes, you blink, or look away -- but after you open your eyes the bright
incoming light may still be there, very close in angle or position to
the terrain or the instruments you have to look at, so you can't really
easily block it.

Missed approach. Problem solved.

All of these effects can be produced at light intensities way, way below
the level that produces any permanent damage to the retina. Though I'm
no expert on this subject, I have also been told that sustained exposure
to this kind of illumination in a situation where you can't just "turn
it off" and where the light levels, although below permanent damage, are
well above what leads to you to blink, and especially if they occur in
stressful situations with demanding performance requirements, can
rapidly lead to various kinds of psychological distress.

Did an "expert" tell you this?

moo

"So you're saying that closing one's eyes or looking away is
reflexive."

Yes, it is called, "Aversion Reflex."

"What length of time would you estimate it takes for that reflex to
occurr? "

About 250 milliseconds.
BTW, the aversion reflex only works in the visible spectrum.

On 31 Jan 2005 13:47:11 -0800, wrote in
.com::

"So you're saying that closing one's eyes or looking away is
reflexive."

Yes, it is called, "Aversion Reflex."

"What length of time would you estimate it takes for that reflex to
occurr? "

About 250 milliseconds.
BTW, the aversion reflex only works in the visible spectrum.

Thank you for the information.

"10Squared" wrote in message

OK, let's see what happens with their most wicked laser. I see the Extreme
Phoenix with a power rating of 500mW.

Their most powerful one is rated at less than 100mw. They claim to use a
500mw diode but the actual output is around 90mw max.

Your 500 mW laser has a power of about .25 mW/cm^2 at 1 km.

Make that .05mw.

moo

"Happy Dog" wrote in message
. ..
"Casey Wilson" N2310D @ gmail.com wrote in

1. Acquire a standard optometrist eye chart.
[A television resolution chart would be a good substitute]
2. Before each exposure, determine visual acuity.
3. After each exposure, repeat acuity test
4. Start at a lower exposure duration and work up.
[This may require performing the test(s) on separate nights]
5. Do the whole thing during the day, facing away from the sun.
6. Chart your work

Hmmm, before step 1, check your medical insurance and have an
optometrist or opthomalogist do a retinal scan, before and after.


Apart from the retinal scan, pointless. The claim is that tiny lasers can
blind pilots. It's bull****. There isn't even a valid theory behind it.
My work is just entertainment.

Truth be told, I agree that the hysteria regarding the lasers, as you
succinctly put it in a later post, is a load of it. My suggestions in the
list were to give your test some data points that, while not scientific,
would show trends, if any. What you end up with may be publishable.