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


At the same time, I don't recall hearing of anyone getting damage from the std
'conference pointer' lasers, or even the middle-school/high school variety.  I
haven't researched it but I don't recall it as a news item

... just like cell-phones at gas stations.  Synthetic fabrics sliding
across plastic car seats can generate static charges, but cell phones have
never been demonstrated to create a spark.



-----Original Message-----
From: owner-atm{at}shore.net [mailto:owner-atm{at}shore.net]On Behalf Of Ken
Hunter
Sent: Wednesday, January 08, 2003 14:26 To: Jerald F. Wright
Cc: atm{at}shore.net
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