I'm going to "Laser" a pilot.

George Patterson wrote:

10Squared wrote:

Why would you give yourself away with a visible beam when
you can use a high powered optical sight?

Ever tried to use one at night?

Well, since this fantasy involves well-equipped evildoers they have night
vision scopes on their invisible ray guns.

What exactly is an LED Laser pointer? It is an LED or a laser; it can't be
both.

Not all lasers are polarized. You can also get unpolarized laser emission.



10Squared wrote in
:

Legrande Harris wrote:

Wouldn't wearing polarized sunglasses just about completely eliminate
the problem of lasers aimed at pilots eyes? The polarization should
completely stop the laser light from coming through the glasses.

Using an LED laser pointer and a pair of polarized glasses I tested
your idea. There is attenuation of the beam that is dependent on the
orientation of the pointer. So, the attenuation depends on how the
person on the other end is holding the pointer.

On Sun, 30 Jan 2005 11:56:49 +0000, 10Squared
wrote:

George Patterson wrote:

10Squared wrote:

Why would you give yourself away with a visible beam when
you can use a high powered optical sight?

Ever tried to use one at night?

Well, since this fantasy involves well-equipped evildoers they have night
vision scopes on their invisible ray guns.

If they're going to use optical scopes and invisible rays, why does it
have to be at night?

Don

Legrande Harris wrote:

In article ,
10Squared wrote:

Legrande Harris wrote:

Wouldn't wearing polarized sunglasses just about completely eliminate
the problem of lasers aimed at pilots eyes? The polarization should
completely stop the laser light from coming through the glasses.

Using an LED laser pointer and a pair of polarized glasses I tested your
idea. There is attenuation of the beam that is dependent on the
orientation of the pointer. So, the attenuation depends on how the person
on the other end is holding the pointer.

How precisely does the pointer have to be aligned? If it is off by 5
degrees does the laser get through?

Yes, the attenuation was proportional to the amount of rotation from 0-90
degrees. In short, it's nothing you could count on to protect you.

In article ,
10Squared wrote:

Legrande Harris wrote:

Wouldn't wearing polarized sunglasses just about completely eliminate
the problem of lasers aimed at pilots eyes? The polarization should
completely stop the laser light from coming through the glasses.

Using an LED laser pointer and a pair of polarized glasses I tested your
idea. There is attenuation of the beam that is dependent on the orientation
of the pointer. So, the attenuation depends on how the person on the other
end is holding the pointer.

How precisely does the pointer have to be aligned? If it is off by 5
degrees does the laser get through?

In article ,
Andrew Sarangan wrote:

Not all lasers are polarized. You can also get unpolarized laser emission.

Yes, but aren't the upolarized lasers quite weak? My only real
experience with lasers was messing around with them in college physics
classes and all the different laser beams could be blocked quite easily
with polarized glass.

Obviously if the laser is strong enough to burn through the glass then
it won't work, but those lasers are not readily available

LG

IF the laser is (linearly) polarized to a fairly high degree (not too
difficult in practice),

and IF the pilot is wearing polarized sunglasses (readily available),

and IF the laser is physically rotated (about its long axis) so that its
direction of polarization exactly matches the linear polarization that
is blocked by the polarized sunglasses (has to be done carefully and
deliberately, to within a few degrees),

and IF there is no deliberate or accidental conversion of the laser
beam's polarization between the laser and the sunglasses (e.g.,
deliberate conversion to circular polarization, effects of scattering,
birefringence in stressed windshield),

THEN only a small amount of the laser light will get through.

Rotate the laser about its axis by 45 degrees in either direction and
half the light will get through (which in terms of "dazzle" effects
means most of it gets through). Between 45 and 135 degree rotation in
either direction, more than half and up to 100% gets through.

The polarization direction of ordinary polarized sunglasses is set in a
certain direction because that's best for minimizing glare from
shallow-angle reflections. Any minimally competent bad guy could
therefore defeat their protection.

[And just for side interest, the LCD screen on my expensive 21" Sun
monitor is polarized exactly wrong, such that you simply can't use it
while wearing polarized sunglasses. The Sun engineers who designed it
knew computers, but not optics. Most laptop screens are polarized at 45
degrees; if you wear polarized sunglasses while using them you block
half the light, which your eye or brain adapts to and you don't even
notice it. Try tilting your head left and right while doing this some
time. I've observed that some of the credit card and signature screens
in California 7/11's also seem to be polarized exactly wrong for
polarized sunglasses.]

Those of us on alt.lasers are having several discussions of this same
topic. Our take is that this is a lot of nonsense, possibly with some
ulterior motive on the part of the government. One person wrote a
letter to one of the government agencies involved, and posted the
reply. The government stands by their story that a doctor (notice, one
doctor) found retinal burns on the pilots he examined (laser source
unknown). We still think it's a bunch of nonsense (several of us have
worked around a lot of lasers, and I, for one, have a degree in Laser
Electro-Optic Technology).

"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.