Re: Flash Blinded By Green Laser

From: Mike Simmons (mikes_at_nospam.mtwilson.edu)
Date: 12/31/04 

Date: Fri, 31 Dec 2004 02:30:55 -0800

On Thu, 30 Dec 2004 22:42:02 -0700, Tim Killian <TJK@notmyrealemail.com>
wrote:

> So tell us, what is the safe distance when someone points a green laser
> in your face? What, you don't know for sure?

I said nothing about a safe distance. I said only that Gary's experience
could not be extrapolated to the distance of an aircraft. Do you disagree
with that?

> Laser beams can be collimated, expanded, even focused (theoretically to
> a spot 1/4 wavelength in diameter). To make a blanket claim that beam
> divergence will always protect bystanders shows you have little real
> understanding of atmospheric propagation.

I didn't say that beam divergence will always protect bystanders, nor did
I make any claim, blanket or otherwise. I said the events could not be
equated, and divergence is a major reason. Other reasons include the
windows on the aircraft and atmospheric scattering and/or absorption.

Where did this stuff about focused beams come from? Are you suggesting
that that's what happened in the incident with the airline pilot? Did
someone track the aircraft with a focused laser beam? Do you have any
evidence for this? If not, what's the relevance of the ray gun talk? Are
you saying that because lasers can be focused Gary's experience was the
same as the airline pilot's? Or are you bringing stuff up just to argue?
Your tone is consistent with that.

In fact, what I objected to might be considered a blanket claim made by
Gary -- the apparent assumption that all events would have identical
results despite very different circumstances. You've pointed out that
variable factors can affect the resulting beam. It seems we agree.

As for my understanding of atmospheric propagation, that's pretty much
irrelevant, but I do have some knowledge of how our observatory's adaptive
optics laser behaves in the atmosphere and how much it diverges at the
height of aircraft and beyond. But even without that I'd guess most
people know that laser beams diverge.

Mike Simmons

>
>
> Mike Simmons wrote:
>
>> On Fri, 31 Dec 2004 04:17:33 GMT, Gary Honis <ghonis@epix.net> wrote:
>>
>>> I've been watching the news channel reports today on green lasers and
>>> the
>>> dangers to pilots. I've also been reading the messages here about
>>> using
>>> green lasers to easily point out objects in the night sky. I don't
>>> own a
>>> green laser pointer but I have a unique opinion of green lasers
>>> because I
>>> was flash blinded by one accidentally turned on by Howie Glatter at a
>>> star
>>> party. When a pilot says he was "flash blinded" by a green laser, I
>>> know
>>> what he experienced and the disorientation that results.
>>
>>
>> No you don't. The pilot of an aircraft will likely be miles from the
>> laser. The beam will diverge greatly at that distance. Equating that
>> (if that's what it was) with your point-blank experience is ludicrous.
>>
>> Mike Simmons
>

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