Happy Dog wrote:

"Casey Wilson" N2310D @ gmail.com wrote in

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.

moo

Although I agree that it is impossible to hold a laser on a sufficiently
small area at the distances described (a 1 degree fluctuation causing a ca.
90 ft. movement at 1 mile if my math is correct), there is valid theory
behind it. Maximum permissible exposure when looking into a laser beam is a
function of exposure time.

For wavelengths of 400 nm to 1.4 um: [1]

t = 1 ns to 2x10^-5 s MPE = 0.0005 mJ cm^-2
t = 2x10^-5 s to 10 s MPE = 1.8xt^(3/4) mJ cm^-2
t 10 s MPE = 10 mJ cm^-2

Laser device in question has a rated power of 5 mW.
1 W = 1 J/s
5 mW = 5 mJ/s

Assuming under the worst case the beam spread results in a beam no bigger
than 1 square centimeter (and there are 2.54 centimeters in an inch), the
exposure NEVER exceeds the MPE, even for very long exposure times. In
reality the beam spread is much greater. A device I tested has a beam
spread of over 2 inches at 50 feet.

How accurately must one be to hold the 1 cm beam on target at the target
distance? Assuming a distance of 1 km, a 1 cm movement is equivalent to an
angular displacement of:

tan a = 1 cm / 1 km = 1 x 10^-2 / 1 x 10^3 = 1 x 10^-5
a =~ .00001 radians =~ 20 arc seconds

So, the whole thing doesn't wash. The power is insufficient, the beam spread
is too great, and the required pointing accuracy is too high.

[1] Jurgen R. Meyer-Arendt, M.D., "Introduction to Classical and Modern
Optics", 2nd ed.