|
I've pretty much kept away from this debate or dicussion, but feel I might
chip in here, this is a post I posted to another group on this very topic...
I'd like to clear a couple of things up about lasers. As there is a lot
of mis-information being put out there. Having worked with high powered
lasers for public display between 1989-2003.
ok, lets have a look at this... and why most of us in the industry think
pilots are stretching the truth. However I do not think it is a good idea to
be pointing these things at any power at anyone head, aircraft or motor
vehicle.
Lets take a 20W argon water cooled laser. At full power the beam/ray
is fired from the head. It exits the head through an optical plate which
focalises the beam at around 1-2mm. I don't believe you could swing
your hand fast enough to avoid burns at a range of half a metre or so
and you will be able to light a cigarette on the beam for several metres.
But then, and depending on the quality of the optical plate the beam will
most probably (actually it's a given fact) begin to converge or diverge
so at around 100+- metres the beam now 150+- mm wide, and a lot of it's
power is dissipating. Still you wouldn't want to look down it especially if
it's static. At say 500-600 metres the beam is now several feet across.
Lets say between 3' to 6' now look back down the beam your 6mm pupil
only takes a very small portion of the light, someone here might be able
to do the maths and let us all know. But it doesn't take a rocket scientist
to work out 3-6mm circle cut out of a 3-6' circle is a very small percentage
of what was a focalised beam. To even get flash blindness you would have to
look directly back down the beam not have it scan over your face. Even then
some of the light will be reflected off the window of the aircraft or car.
You would have to do it for a period of time, I dont imaging a hand held
divice could be that accurate...
Which comes to the next impossibility. Let's say we had the ability to
make the optical plate that well (up until when I last worked with lasers
they hadn't) That you could keep the beam focalised along it path without
it converging or diverging from the 1-2mm beam being fired. Now you have
something that can do damage. Ok, but what's the possibility of hitting a
6mm target travelling at speed that is also moving around in it's own
environment. Say the pupil of someone driving, a pilot flying...etc...etc...
you not going to do that by hand. The laser head of a 20W argon (water
cooled) is a 2 man lift in itself. And I'm not sure there is a guidance system
available to do the job yet. Plus 64 amp 3phase to power the sucker, 50psi
clean water source. So what do you think the chances are of your little hand
held laser powered by a couple of "AA" batteries will do??
Sorry but a hand held laser pointer even a fairly powerful one is going to
have _zero_ chance at flash blinding pilots. And most of us that have worked
with lasers silently chuckle at stories from pilots to say they were. BUT! we
all agree it is a stupid thing to do. It is dangerous looking directly down the
source of a laser beam under most conditions if not all. But there is a lot of
un-informed scare stories being touted about which in it's self is not fair on
the actual laser. I've worked with high power lasers for public displays,
corporate events, rave & dance parties x 300+ almost all these shows
involved crowd scanning (which is still legal in this country) and with some
events with crowds up to 50,000 people. Using lasers from 100mW through to
20W and never had one complaint about flash blindness or disorientation or
eye injury due to lasers. And I can ensure you my eyes have been scanned
across dozens of times on each night. The only known case that I know of
regarding blindness had happen in the eastern block country. Where some
promoter of a rave event used a copper based pulse laser. Pulse lasers are
the most dangerous to our eyes and are the type steal companies use to cut
steal and are a lot more powerful.
Also having heard several reports of motor vehicle being hit over the years,
ever hear of a driver being flash blinded???... disorientated and crashed???...
hmmmm only seems to happen in the air... strange... I mean if a car driver
got flash blindness at 100kph (traveling 100m every 4 seconds, according
to Dr Carl) you would of thought you would of heard of a motor car accident
by now eh'
regards,CS
|