Flash Blinded By Green Laser

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=20
experiment.


Chris never said that. He said "transient exposure" to a 5mW beam=20
won't/can't do any damage.

-Florian

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.

It seems from the news reports that indeed the lasers that have been flashing
the pilots are causing them some disturbance.

To me the mere fact that the pilots have been able to see the lasers in the
cockpit is an indication that these beams are have not diverged a great deal.

Personally I would not want to be a passenger in a plane that is landing and
have the pilot be temporarily blinded by flash from a green laser.

Again, in several threads over the past few years I have pointed out that there
were/are vendors openly selling green lasers greater than 50mw without any
safety instructions other than pointing to a page which discusses the work done
on Class 3A red lasers. If I recall, Zbolt was one of the vendors. I consider
this irresponsible and hope these guys get nailed....

jon

On Tue, 04 Jan 2005 23:59:23 -0700, Tim Killian wrote:

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.

What I said was a _transient exposure_ would not cause damage. A transient
exposure occurs as the result of an accident, and is limited in duration
(typically to a fraction of a second) by the combination of moving source and
ocular aversion reflex. I also said that the experimental evidence shows that
exposures of many seconds do not appear to cause retinal damage, although such
exposures obviously do not occur by accident.

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.

Obviously, it is reasonable to limit the power of lasers brought to public
events. Have I suggested otherwise? We freely allow people to carry water
pistols, we let children beyond a certain age have BB guns, adults have rifles,
and almost nobody is allowed machine guns or grenades. But we don't take away or
regulate water pistols just because machine guns happen to exist.


How long can a
person look into a 20 mW green beam? Or should we worry more about being
struck by lightning?

A transient exposure to a 20mW laser (the color isn't very important) is
unlikely to cause retinal damage, although such an exposure should be avoided.
In one case I saw a lesion caused by a direct hit from a 25mW IR laser. The
individual involved felt the beam hit his cornea, and had a visible lesion on
the retina (by ophthalmoscope), but no detectable vision loss.

_________________________________________________

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

From today's news reports:
.......................................
"NEWARK, N.J. - A man charged with temporarily blinding the pilot and
co-pilot of an airplane with a laser beam claims he was simply using the
device to look at stars with his 7-year-old daughter."

"Federal authorities Tuesday used the Patriot Act to charge a man with
pointing a laser beam at an airplane overhead and temporarily blinding the
pilot and co-pilot."

"Banach, 38, of Parsippany admitted to federal agents that he pointed the
light beam at a jet and a helicopter over his home near Teterboro Airport
last week."

"He was accused of interfering with the operator of a mass transportation
vehicle and making false statements to the FBI, and was released on $100,000
bail. He could get up to 25 years in prison and fines of up to $500,000."

"Banach's lawyer, Gina Mendola-Longarzo, said her client was simply using
the hand-held device to look at stars with his daughter on the family's
deck. She said Banach bought the device on the Internet for $100."

"The jet, a chartered Cessna Citation, was coming in for a landing last
Wednesday with six people aboard when a green light beam struck the
windshield three times at about 3,000 feet, according to court documents.
The flash temporarily blinded both the pilot and co-pilot, but they were
later able to land the plane safely, authorities said."

"Not only was the safety of the pilot and passengers placed in jeopardy by
Banach's actions, so were countless innocent civilians on the ground in this
densely populated area," said Joseph Billy, agent in charge of the FBI's
Newark bureau."

"Banach told the agents it was his daughter who shined a beam at the
helicopter, according to court papers. He denied the laser was in use when
the jet had passed nearby. But later, Banach submitted to a lie detector
test and eventually said he shined the
laser beam at both aircraft, according to the court papers."

"For the past seven months, Corvallis entrepreneur and inventor John Acres
has sold a laser light that throws a green beam high into the sky. Plenty of
other companies make similar lights, but Acres claims he already has 10
percent of the market. The FBI, however, is interested in only one laser
light he produced for $119 retail. It apparently landed in the hands of a
New Jersey man who admitted shining the laser beam last week at a chartered
plane and a helicopter flying over his home, authorities said. Acres said
the FBI asked him questions about the light used by David Banach of
Parsippany, but he declined to discuss details of the conversation."

"Its most popular use is by astronomy hobbyists and students to point out
individual stars in the sky, Acres said. The beam can go for several miles,
depending on the clarity of the air, he said. Bird-watchers also use the
light to spot species on tree limbs, though they're cautioned not to shine
the penetrating light into birds' eyes, Acres said."

"Mr. Banach ordered the green laser pointer online from an Oregon company
called BigHa, Ms. Longarzo said. The company's Web site, bigha.com, displays
photographs of green laser beams shooting into space but warns customers not
to aim at any homes or aircraft."
.................................

Based on these reports, a Class IIIa green laser pointer was used. Both the
pilot and co-pilot were temporarily blinded by the flash at 3000 feet. This
contradicts claims made by some here that this is not possible.

On bigha's web site I noticed that the $119 Class IIIa 5mw green laser
(Jasper Model) sold by bigha.com has sold out.

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

On Wed, 05 Jan 2005 15:20:49 GMT, "Gary Honis" wrote:

From today's news reports:
......................................
"NEWARK, N.J. - A man charged with temporarily blinding the pilot and
co-pilot of an airplane with a laser beam claims he was simply using the
device to look at stars with his 7-year-old daughter."

"Federal authorities Tuesday used the Patriot Act to charge a man with
pointing a laser beam at an airplane overhead and temporarily blinding the
pilot and co-pilot."

Based on these reports, a Class IIIa green laser pointer was used. Both the
pilot and co-pilot were temporarily blinded by the flash at 3000 feet. This
contradicts claims made by some here that this is not possible.

"Temporarily blinded" means nothing more than the loss of dark adaptation-
something pilots are trained to deal with (a nearby lightning strike, for
instance, would cause this kind of effect).

It is important to distinguish between being dazzled and suffering actual
physical damage. Of course, there are specific situations where simply being
dazzled could be dangerous, and that's why there are laws in place to punish
people who do stupid things like deliberately shining lasers (or spotlights, for
that matter) at aircraft or automobiles.

Using the Patriot Act to charge this guy is a gross abuse of authority.

_________________________________________________

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

"Chris L Peterson" wrote in message
...
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

it never ceases to amaze me how illogical and irrational such decisions are.
After tons of studies, government , media and the public end up invariably
adopting the worse options .
I wish they decided to ban cellphones at least in cars. Instead , we can
talk all we want and get into more car crashes than any other civilised
nation (are we really a civilised nation is a different debate that I'm not
willing to open now) . Probably more people get brain tumors due to cell
phones than vision damage due to green lasers.
Eat fast food and never walk even 100 yards a day, become obese must all be
good for public safety . But be careful and ban green lasers, they're public
enemy number one. Good thing though ban on assault weapons is not needed
anymore . Probably year 3000 historians will have a difficult time
understanding the idiosyncrasies of 21st century stone age .

best regards,
matt tudor

"Chris L Peterson" wrote in message
...
On Wed, 05 Jan 2005 15:20:49 GMT, "Gary Honis" wrote:

From today's news reports:
......................................
"NEWARK, N.J. - A man charged with temporarily blinding the pilot and
co-pilot of an airplane with a laser beam claims he was simply using the
device to look at stars with his 7-year-old daughter."

"Federal authorities Tuesday used the Patriot Act to charge a man with
pointing a laser beam at an airplane overhead and temporarily blinding
the
pilot and co-pilot."

Based on these reports, a Class IIIa green laser pointer was used. Both
the
pilot and co-pilot were temporarily blinded by the flash at 3000 feet.
This
contradicts claims made by some here that this is not possible.

"Temporarily blinded" means nothing more than the loss of dark adaptation-
something pilots are trained to deal with (a nearby lightning strike, for
instance, would cause this kind of effect).

It is important to distinguish between being dazzled and suffering actual
physical damage. Of course, there are specific situations where simply
being
dazzled could be dangerous, and that's why there are laws in place to
punish
people who do stupid things like deliberately shining lasers (or
spotlights, for
that matter) at aircraft or automobiles.

Using the Patriot Act to charge this guy is a gross abuse of authority.

_________________________________________________

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

it's really interesting to note the tone all these anouncements have. They
talk about "penetrating beam" , "airplane was hit" , "pilots were still able
to land the plane safely" "temporarily blinded" etc. They make it sound as
if this really was Darth Vader's light saber . That laser is no more
penetrating than a flashlight . A grain of dust hitting the airplane would
have more energy than that laser beam . The words used by the media do
however suggest to the large masses some sort of attack action . Idiots
would believe it was an industrial metal cutting laser .
I fail to see how someone could be charged for shining a class 3a laser at
anything or anyone. It would be legal to shine it all day long , that's why
they're sold as class 3a . Class 3a is legal. If they didn't want people
shining them at airplanes, it should've been decided before allowing these
lasers as legal. I don't recall class 3a devices being sold under the
provision of having to be fearful of using it anywhere, for example at night
pointing up . There's no mandatory use of radar or night vision devices to
dtect night flying airplanes before using a class 3a green laser. If
anything, our laws and law enforcement are suffering a great disconnect and
acting in a contradictory manner. It used to be that we had laws but nobody
wa enforcing them. Now's the opposite, they're seeking penalties for actions
that are legal.

best regards,
matt tudor

it's really interesting to note the tone all these anouncements have. =
They
talk about "penetrating beam" , "airplane was hit" , "pilots were still =
able
to land the plane safely" "temporarily blinded" etc.


One report said the plane was "targeted". Blah. People seem to think =
that laser light is somehow dangerous just because it's laser light. =
Like it's radioactive or something.

BTW, my green laser arrived from z-bolt.com today! Very quick service. =
Seems a very nice solid unit. I'll try it out tonight from home and see =
how it working in pointing out Machholz to my wife and son. ;-)

-Florian

Stuart Levy wrote:
I have a 5mW green laser, and have tried shining it into my own eye
--
briefly (1 second or so) but at short range, so that the beam
diameter
was smaller than my pupil -- while dark adapted.

If your eye is focused at infinity, then a laser will focus its output
on a very tight area of your retina. If it is held at a 'short
distance' then your eye is not focused at infinity and you don't get
the total effect. If the beam has diverged less than the diameter of
your pupil then you would be getting its full output.

If some one shined a laser in MY eye, or the eye of some one in my
family, I'd react in a way that would probably get me arrested.
Steve O.

Chris Peterson 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.

and:

"I also said that the experimental evidence shows that exposures of many
seconds do not appear to cause retinal damage, although such
exposures obviously do not occur by accident.

As a laser safety officer, how can you make such reckless statements on a
public forum?

The Laser Institute of America web site has added a "quicklink" on laser
safety information because of concern "about the lastest interest in laser
pointer safety":

http://www.laserinstitute.org/

It includes:

"The Laser Institute of America and the American Academy of Ophthalmology
have also received reports of people exposed for longer amounts of time,
including

two verified retinal injuries caused by intentionally staring into pointers.
"

Concerning telescopes/binoculars, according to the Australian Radiation
Protection and Nuclear Safety Agency (ARPANSA):

"Class 3A laser products emit higher levels of radiation and more stringent
precautions are required than those necessary with Class 2 laser products.
They differ from Class 2 products in that they emit more power in a beam of
larger cross-section, so that when the output is directly viewed, the power
of the beam entering the eye (does not exceed that of a Class 2 product (the
pupil diameter is assumed to be 7 mm). However, if the beam is viewed
through larger diameter collecting optics (e.g. binoculars) then the hazard
is usually increased. "

Chris Peterson also wrote:

Every time you even glance at the Sun you are putting more stress on your
retina than a low power laser can induce.


According to a warning issued by the FDA at
http://www.fda.gov/bbs/topics/NEWS/NEW00609.html titled "FDA ISSUES WARNING
ON MISUSE OF LASER POINTERS":

"The light energy that laser pointers can aim into the eye can be more
damaging than staring directly into the sun."

Dark Skies,

Gary

"Chris L Peterson" wrote in message
...
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