Flash Blinded By Green Laser

That's his problem,. isnt it! Moron.



epistle to dippy wrote:

On Sat, 01 Jan 2005 23:24:53 -0600, Yukovnia wrote:

his, and there should be nothing to have to "interpret"!

People here at SAA have the luxery of discussing this, socalled.
People in cockpits dont have that luxery. If you dont see that, you
dont see anything!

John, Lt Col USAF retired -

Then present your "case" to the FCC and see how far you get,
Pudknocker!

John

One would think a "Lt. Col USAF retired" would know the difference between
the agency that regulates nipple exposure at Superbowl half-time shows and
the agency that regulates commercial air traffic.

E2D

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or your nerve shattered ego?


Brian Tung wrote:

JW, I think you need to rest your poor aching head.

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

"Bolond" wrote:
or your nerve shattered ego?

Why, Jerry, you wound me and my quite ample ego. But not, I don't think,
irrecoverably so.

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

Two news articles on NJ man that lit up helicopter cockpit with 5mw green
laser:

http://tinyurl.com/6jd65

and New York Times:
http://www.nytimes.com/2005/01/03/nyregion/03laser.html

The second article has a link to the laser company, bigha.com, that
includes "actual owner" astro picures with green laser streaks in its
advertising, "Share your love of the night sky".

Yet again....two more green laser hit on plane incidents in Nashville and
Chicago reported yesterday.

Dark skies,

Gary


"Chris L Peterson" wrote in message
...

Thanks for the link. While I don't particularly agree with the findings
(that
is, I think the FAA requirements are unnecessarily strict), it doesn't
change my
main point that laser pointers are not a safety hazard. That doesn't mean
that
someone couldn't go out of their way to use a pointer in an unsafe way
(standing
at the end of a runway and aiming at a plane, standing on an overpass and
aiming
into oncoming traffic, etc). Realistically, I don't see laser pointers
being
used as astronomical tools in locations where air traffic is low enough to
meet
the requirements given in the above report, let alone low enough to
genuinely be
a problem to pilots. There are plenty of ground-based light sources that
are
much brighter than class 3a lasers and which could easily shine into
cockpits.
Singling out lasers doesn't make a lot of sense to me.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

wrote:
snip
12/31/04 addendum from Howie:
The only positive development to come out this that I know
of is that I've belatedly taken up an idea and suggestion
that Frank Bov made to me a few years ago to place a thin
full diameter O-ring between the collimator battery and the
battery cap (Thanks, Frank!). It prevents inadvertent
activation from shakeing and vibration. I'm supplying them
now, and I plan to send them to past purchasers of my
collimators. - H.

Howie,

I think your experience points out an inherent design defect in some
laser collimators on the market today - that the laser can be left in
an unattended "on" mode.

Although apparently not required by OSHA or FDA regulations for Class
IIIA laser, all the laser pointing devices I own (a red laser pointer
for aligning objects on my hobbyist optics bench and a green astronomy
laser pointer) all have a safety dead man's switch. The laser cannot
be operated unless the user actively pushes and holds a button in the
"on" position. (For use on an optical bench I have to defeat the red
laser's dead man's switch with a caliper.)

Unlike these other common consumer lasers, telescope laser collimators
(although I do not own or use one) apparently are designed to work in a
permanent "on" mode -

http://www.telescope.com/jump.jsp?it...2C2%2 C6%2C30

http://www.telescope.com/shopping/pr...roduc tID=106

The simple safety design solution is that they should have a dead-man
ball button in the telescope barrel end of the collimator. Then the
laser can only be in the "on" emitting position when the collimator is
inserted in the telescope barrel. The laser collimator would
automatically turn off when removed from the telescope barrel.

Such a ball switch would bring these devices within line with current
safety design features in the consumer laser product industry.

Just an idea.

- Canopus56

See also references in my usenet post:

In thread "Laser lunacy"
Date: 3 Jan 2005
Message-ID: .com

OHSA Manual Summary of required laser safety features by laser class:
http://www.osha.gov/dts/osta/otm/otm...m_iii_6.html#6
http://www.osha.gov/dts/osta/otm/otm...ml#app_iii:6_1

Chris L Peterson wrote:
On Sun, 02 Jan 2005 14:15:03 GMT, "Gary Honis"
wrote:
snip[i]
t doesn't change my main point that laser pointers are not a
safety hazard.
That doesn't mean that someone couldn't go out of their way to use a
pointer in
an unsafe way . . .

Safety standards and issues surrounding airports, which for years have
had special regulations creating "laser free" zones necessary for pilot
and passenger safety, are not directly applicable analogies to laser
safety at star parties. The safety need to preserve night adapted
vision and prevent distractions in the aviation setting exceeds safety
needs appropriate at amateur star gatherings.

Star parties have a different set of safety needs and social etiquette
concerns.

The safety concern, illustrated by the unfortunate incident at the
Cherry Springs Star Party with a red laser collimator discussed in this
thread, illustrates the safety problem:

What injury can result if a green laser pointer or red laser collimator
accidently strikes the primary mirror of another amateur at a star
party, while the scope is in use?

My own informal home experiments with a green laser are that if the
collimated laser beam strikes the primary with a 40mm-20mm (36x-60x)
lens in the eyepiece, a well-collimated laser beam still comes out the
eyepiece. This occurs even when I tested the beam a distance of 20
feet. Only when a very high-magnification eyepiece is in use does a
diffuse beam come out the exit pupil of eyepiece that would present
less risk to the telescope user (since the concentrated energy of the
laser beam is spreadout over 50 degrees of the eyepiece's apparent
field of view). The brightness and size of the laser beam was observed
by holding up a piece of white paper behind the eyepiece at the eye
relief distance.

(A safety disclaimer: Of course I did not actually look into the
eyepiece to see how bright the laser was. Anyone reading this should
be aware that looking into the eyepiece in such circumstances might
cause serious, permanent eye injury. Do not do it.)

In this regard, it might be useful to visualize telescope users at a
star party as walking around with 8" to 12" "owl"-like eyeballs
attached to their heads. Telescope inclination discounted, the
probability of an accidental eye strike with a laser pointer or laser
collimator is much greater as compared to a crowd of persons simply
standing on a football field - where the potential hazard target -
their 6mm eye pupil - is small as compared to a telescope's primary
mirror.

The only data on the nominal hazard zone for laser pointers that I
could easily come up with was for more powerful Class IIIb lasers.
Flash/blindness and afterimages is a known biological effect at up to
262ft; glare annoyance is a problem at approx. 1200ft. A 300 ft
football field pretty much covers the area taken up by 90% of star
parties I have been to.

Since collimanted laser beams do not appear to appreciably change in
density as they pass down a telescope tube and up and out the eyepiece,
these hazard zone distances are probably a good rough beginning
guideline for defining the size of a laser pointer hazard zone at a
star party.

The above is intended as an attempt to roughly quantify the safety risk
and hazard zone when using red laser collimators and green laser
pointers at star parties.

As to the social annoyance and astrophotography hazard posed by green
laser pointers, that seems to be a problem that can be resolved by
social etiquette. Green laser pointers are not unlike the annoyance of
car headlights at star parties - something that the amateur observing
culture seems to deal with as a social problem with little difficulty.


My own experience with green laser pointers as teaching aides is that
the usefulness of this new consumer technology far outweighs its
supposed risks. All new consumer technology has a teething period
until an agreed informal code of social conduct emerges. Of course,
safety always comes first. Nothing happens at a star party that
warrants a temporary or permanent eye injury.

Enjoy - Canopus56

Appendix A

================================================
Excerpt from Rockwell "Safety Recommendations of Laser Pointers"

Rockwell, Jr., James R., and Ertle, William J., Rockwell Laser
Industries, Moss, C. Eugene, National Institutes of Occupational Safety
& Health. Undated. Safety Recommendations of Laser Pointers.
http://www.rli.com/resources/pointer.asp undated, accessed 1/5/2005


The NHZ associated with open-beam Class IIIB and Class IV laser
installations can be useful in assessing area hazards and implementing
controls. The summary in Table 1 shows the magnitude of the NHZ's for a
visible frequency laser pointer emitting 5mW:


Table 1


Nominal Hazard Zones for Visible Diode Pointers
Power: 5 mW - Divergence: 1 mr - beam size: 2 mm
Based on: FAA 74002D Outdoor Laser/High Intensity Light Demonstrations


Bioeffect MPE Level * Nominal Hazard Zone
Condition (W/cm2 ) (feet)


BLINK REFLEX 2.6 x 10-3 51


FLASH-BLINDNESS
/AFTERIMAGE 100 x 10-6 262


GLARE 5 x 10-6 1,171


"NO EFFECT" 50 x 10-9 11,707


[ MPE = Maximum premissible exposure ]


The different visual effect "MPE" criteria used in the NHZ computations
in Table 1 were are based upon the U.S. Standard for the Federal
Aviation Administration: FAA 74002D Outdoor Laser/High Intensity Light
Demonstrations which provide a numerical basis for the various
bioeffect criteria [6].


(6) FAA 74002D Outdoor Laser/High Intensity Light Demonstrations: From
Chapter 34: Outdoor Laser/ High Intensity Light Demonstrations, Federal
Aviation Administration
=================================================

On 4 Jan 2005 17:16:49 -0800, "canopus56" wrote:

What injury can result if a green laser pointer or red laser collimator
accidently strikes the primary mirror of another amateur at a star
party, while the scope is in use?

None. You can deliver the entire 5mW output of a laser into the eye and there
will be no damage. Adding a telescope doesn't change that. Furthermore, I don't
think the scenario of a laser making it down a telescope aperture and out an
eyepiece is very realistic. This could only happen if the telescope was in a
horizontal position with someone at the eyepiece. Combine the likelihood of this
unusual position with someone hitting the scope with a laser at the same time.
I'd be more worried about getting hit by lightning.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

I'm stunned at the hubris it takes to make a blanket statement like
this. Look at the studies and safety guidelines -- with minimal
concentration, a 5 mW beam can produce significant vision impairment,
even retinal damage. Anything from an electronic failure in the
regulator circuit, to an unfortunate alignment of optics could cause
that concentration. Such injuries may be unlikely, but I simply don't
understand the cavalier attitude expressed, and the chances you're
willing to take with other people's vision.


Chris L Peterson wrote:

None. You can deliver the entire 5mW output of a laser into the eye and there
will be no damage. Adding a telescope doesn't change that. Furthermore, I don't
think the scenario of a laser making it down a telescope aperture and out an
eyepiece is very realistic. This could only happen if the telescope was in a
horizontal position with someone at the eyepiece. Combine the likelihood of this
unusual position with someone hitting the scope with a laser at the same time.
I'd be more worried about getting hit by lightning.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On Tue, 04 Jan 2005 23:13:19 -0700, Tim Killian wrote:

I'm stunned at the hubris it takes to make a blanket statement like
this. Look at the studies and safety guidelines -- with minimal
concentration, a 5 mW beam can produce significant vision impairment,
even retinal damage. Anything from an electronic failure in the
regulator circuit, to an unfortunate alignment of optics could cause
that concentration. Such injuries may be unlikely, but I simply don't
understand the cavalier attitude expressed, and the chances you're
willing to take with other people's vision.

With all due respect, you don't know what you are talking about. I have worked
as a laser safety officer for a major biomedical company, and have years of
experience in ophthalmology and ophthalmic instrumentation. A transient exposure
to a collimated beam under 5mW anywhere in the visible range will not damage the
retina. There is no literature to suggest otherwise, and a good deal of evidence
from experiments carried out on diseased eyes to demonstrate the relative safety
of class 3a lasers. It takes many seconds of continuous exposure at 5mW to cause
damage (and that is from phototoxicity, not thermal effects). Every time you
even glance at the Sun you are putting more stress on your retina than a low
power laser can induce.

What are you suggesting? That there will be a simultaneous combination of a
laser failure leading to a high output energy, with that laser being directed
straight into a telescope (within a degree or so of its optical axis), and a
person (possibly with an eye pathology) at the eyepiece? Well, it obviously
isn't impossible, but neither is it something that demands much concern. At any
star party, the proliferation of AC inverters (without any kind of ground fault
protection at all) under dark, dewy conditions is orders of magnitude more
hazardous. I don't see a big movement to ban those. Really, this concern about
low power laser pointers is irrational, and borders on hysteria.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

For argument's sake, let's throw caution to the wind. According to you,
we can stare, point blank, into 5 mW green lasers until we tire of the
experiment. Just another bright light, ho-hum. So tell us, what will
happen when toys like these start showing up at star parties:

http://store.yahoo.com/deharpport/inladimo1.html

The prices for these modules are about what 5 mW units fetched two years
ago. I'm sure they'll more affordable in a few months. How long can a
person look into a 20 mW green beam? Or should we worry more about being
struck by lightning?

Chris L Peterson wrote:

On Tue, 04 Jan 2005 23:13:19 -0700, Tim Killian wrote:


I'm stunned at the hubris it takes to make a blanket statement like
this. Look at the studies and safety guidelines -- with minimal
concentration, a 5 mW beam can produce significant vision impairment,
even retinal damage. Anything from an electronic failure in the
regulator circuit, to an unfortunate alignment of optics could cause
that concentration. Such injuries may be unlikely, but I simply don't
understand the cavalier attitude expressed, and the chances you're
willing to take with other people's vision.


With all due respect, you don't know what you are talking about. I have worked
as a laser safety officer for a major biomedical company, and have years of
experience in ophthalmology and ophthalmic instrumentation. A transient exposure
to a collimated beam under 5mW anywhere in the visible range will not damage the
retina. There is no literature to suggest otherwise, and a good deal of evidence
from experiments carried out on diseased eyes to demonstrate the relative safety
of class 3a lasers. It takes many seconds of continuous exposure at 5mW to cause
damage (and that is from phototoxicity, not thermal effects). Every time you
even glance at the Sun you are putting more stress on your retina than a low
power laser can induce.

What are you suggesting? That there will be a simultaneous combination of a
laser failure leading to a high output energy, with that laser being directed
straight into a telescope (within a degree or so of its optical axis), and a
person (possibly with an eye pathology) at the eyepiece? Well, it obviously
isn't impossible, but neither is it something that demands much concern. At any
star party, the proliferation of AC inverters (without any kind of ground fault
protection at all) under dark, dewy conditions is orders of magnitude more
hazardous. I don't see a big movement to ban those. Really, this concern about
low power laser pointers is irrational, and borders on hysteria.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com