From: "Richard Schwartz" 
To: "Ken Hunter" ,
        "Jerald F. Wright" 
Cc: 
Reply-To: "Richard Schwartz" 


There is a real terrorist threat possible with those fountain pen lasers,
so I have no doubt that the gubbermint will soon outlaw them.    I like to
use
mine to play tag with the alley cat at night.



----- Original Message -----
From: "Ken Hunter" 
To: "Jerald F. Wright" 
Cc: 
Sent: Wednesday, January 08, 2003 12:26 PM Subject: Re: ATM LASER SAFETY
was... ATM Web Sight update


>
> Several years ago there were experiments made of bouncing a laser beam
> off of the retro reflectors left on the moon by the Apollo astronauts. The
experiments were designed to measure the
> distance changes between the Moon-Earth. If I recollect properly the
scopes used were in the 12-16 inch category and the
> lasers were fairly low power (like the kind you find in the old Super
Market scanners).
>
> All lasers are regulated in the U.S. and you will see a label on them
stating so. There are different classes depending
> on the power output, purity and frequency. The small hand held laser
pointers were outlawed by NOAA (where I now work)
> for a time and then the restrictions were relaxed last year. They can now
be used for conferences again. I wasn't privy
> to the details but they seem to think they are safe to use.
>
> While working at the Yuma Proving Ground around High Powered Lasers used
in Defense Systems, I was required to have my
> eyes photographed (inside and out) twice a year just in case there was any
question of eye damage resulting from work
> related tasks. It does NOT take much power to permanently destroy the
light receptors in small areas of your eye.
>
> Be Careful...
>
> Ken Hunter
>
> ----- Original Message -----
> From: "Jerald F. Wright" 
> To: "Scott Ewart" 
> Cc: 
> Sent: Wednesday, January 08, 2003 1:19 PM
> Subject: Re: ATM Web Sight update
>
>
> >
> >
> >
> > Scott Ewart wrote:
> >
> > >     Just how much power do you think these things have, anyway?  It's
a few
> > > milliwatts!  And I seriously doubt they're focused well enough to harm
> > > anything more than a mile away.
> > >     Astrophotographers are all worried about having an exposure ruined
by a
> > > laser, but has anyone anywhere EVER seen or heard of a photo with even
a
> > > hint of green laser?  Same with pilots.  Have any ever actually seen a
green
> > > dot on the ground?
> > >
> > > Scott
> >
> >     The laser pointers are "probably" not a big
problem. The laser I was
injured
> > by (and that is the proper way to state it) was not a pointer. It was a
larger
> > one about half the size of a shoe box. I don't know the power. My
statement was
> > that I think at some power level lasers should be regulated.  I probably
over
> > stated that and should have said may need regulation depending on the
frequency
> > of injury by them.
> >
> >     Actually I have heard of two incidents of pilots at least being
temporarily
> > visually impaired by lasers. One was widely reported and involved a U.
S. Navy
> > pilot being lasered by a Russian Ship.  This one was obviously a
military laser
> > probably well beyond the power we are using in amateur astronomy and
probably
> > with a wide beam.  So I discard this one as not relevant to what we are
talking
> > about.  The other I can't put much stock in either.  I only heard one
news
> > report (not an in depth report) of a airline pilot that claimed his
vision was
> > impaired in flight by what he "thought" was a laser.  I
just don't know
if I
> > should believe it.  I think it would be incredibly difficult to point a
narrow
> > laser beam in a pilots eye more than a few micro seconds from a distance
of a
> > mile or more because of the obvious problems of pointing at such a small
target
> > at all let alone tracking.  But a high power laser could be made to have
a
> > diverged beam to cover a significantly wider area at the target and
still
> > deliver significant power into someone's eyes. It would be interesting
to search
> > the NTSB and FAA sites to see if there have been reported instances not
related
> > to military situations.
> >
> >     No. I do not believe the typical laser pointers are a big hazard
that should
> > be regulated.  Some do seem quite bright, particularly the green ones.
So I
> > still wouldn't want people being foolish and pointing the beam at or
near
> > anyone's eyes.  Just a little common sense goes a long way.  Keep in
mind that a
> > few milliwatts or even part of a milliwatt concentrated in a beam that
will
> > entirely fit through the pupil of your eye is thousands of times the
power level
> > normally reaching your retina.  And it is focused by the lens of your
eye to an
> > extremely small point on your retina. And if you happen to be looking
somewhat
> > directly in the direction of the laser it is on the most sensitive part
of the
> > retina.  When a light shines in your eye it is natural instinct to look
directly
> > at it to see where it is coming from.
> >
> >     The problem I had after getting zapped in the eye for less than 1/10
second
> > was that the part of the retina used in seeing fine detail was injured.
In some
> > ways I could see normal such as the panoramic view.  But when I narrowed
my
> > attention to detail it was not there in my right eye.  I could not read
a
> > printed word with that eye and even had difficulty recognizing a face
with my
> > right eye alone.  My right eye is my dominate eye, the one I use for
shooting,
> > telescope viewing, and other such things.  My left eye was normal and
that leads
> > to a sense that there is no trouble at times and much at other times. I
could
> > see pretty much normal most of the time.  It is when you choose to
narrow your
> > attention to some fine detail that requires that extra resolution in
your
> > dominate eye that you know something is for sure wrong.  It is a strange
> > feeling. Try covering your dominate eye and read a page of a book.  Then
cover
> > the non dominate eye and read another page. You will
"see" that it is
easier
> > with your dominate eye. If your dominate eye's retina has has been
blinded in
> > that high resolution part of the retina it greatly interferes with the
non
> > dominate eye in resolving the print. It is even harder to read than just
> > covering the dominate eye.  Your dominate eye keeps trying to find what
the
> > other eye is seeing in order to see it better. But it can't see a
particular
> > letter at all unless you move your eye to the next letter which it won't
be able
> > to see but you can see the ones adjacent but not as well enough to
satisfy the
> > brain so your eyes wiggle. Interestingly if you use only the injured eye
you
> > don't see a spot where you can't see.  Your brain merges what it can
see.  If
> > you look at the printed word THE and try to look directly at the H you
see TE
> > not T  E as I think most would expect. Think how difficult it would be
trying to
> > read like that!
> >
> >     I am not terribly worried about pilots being blinded by an amateur
> > astronomers laser.  I am more worried about others nearby. And
particularly
> > myself after what was fortunately a relatively short experience with the
> > debilitating effects of being zapped by one.  Even if you don't think
they are
> > powerful enough to injure, put effort into not finding out if you are
right.
> > Use them for the intended purposes and don't abuse them risking the
eyesight of
> > others or yourself.  It would be terrible to find out that those little
suckers
> > really can blind.
> >
> > Jerry
> >
> >
> >
> >
>
>

--- BBBS/NT v4.00 MP