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 | | From: | Joseph Gwinn | | Subject: | "Laser Safety in Sight" article in Aviation Week | | Date: | Sun, 16 Jan 2005 18:40:22 -0500 |
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 | On the matter of airplane pilots being blinded by laser light from the
ground, the 10 January 2005 issue of Aviation Week & Space Technology
magazine ran on page 42 a 1.5-page article on the subject, "Laser Safety
in Sight". The article doesn't seem to be available online without
getting a paid subscription, but most public libraries get Aviation
Week, which is the Newsweek of the aircraft industry.
The article reports that on 22 September 2004, a green light striking a
Delta Air Lines flight approaching Salt Lake City caused a retinal burn
to the first officer's eyes. The altitude, speed, and slant ranges were
not reported, but one assumes that the aircraft was at least at a few
thousand feet and traveling a few hundred miles per hour. I find it
hard to believe that any handheld laser could have achieved the retinal
damage threshold. How powerful are the big truck-mounted water-cooled
lasers used for outdoor light shows? My guess is that that aircraft was
illuminated by such a laser.
The article also reports that handheld lasers are limited to 5
milliwatts, while the green star-pointing lasers used in "astronomy
research" can be 75 milliwatts. I seriously doubt that the amateur star
pointers exceed 5 mw.
The article reports that in June 2004 the FAA's Civil Aerospace Medical
Institute published a study titled "The Effects of Laser Illumination on
Operational and Visual Performance of Pilots During Final Approach". (I
haven't gotten this report yet.)
Anyway, perhaps this study contains enough information to do the obvious
analysis of received optical power -- can an ordinary handheld laser
pointer really do much of anything to a airplane pilot? My instinct is
that it cannot, never mind cause retinal burns.
Joe Gwinn
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| | From: | Sam Goldwasser | | Subject: | Re: "Laser Safety in Sight" article in Aviation Week | | Date: | 16 Jan 2005 19:40:34 -0500 |
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| Joseph Gwinn writes:
> On the matter of airplane pilots being blinded by laser light from the
> ground, the 10 January 2005 issue of Aviation Week & Space Technology
> magazine ran on page 42 a 1.5-page article on the subject, "Laser Safety
> in Sight". The article doesn't seem to be available online without
> getting a paid subscription, but most public libraries get Aviation
> Week, which is the Newsweek of the aircraft industry.
>
> The article reports that on 22 September 2004, a green light striking a
> Delta Air Lines flight approaching Salt Lake City caused a retinal burn
> to the first officer's eyes. The altitude, speed, and slant ranges were
> not reported, but one assumes that the aircraft was at least at a few
> thousand feet and traveling a few hundred miles per hour. I find it
> hard to believe that any handheld laser could have achieved the retinal
> damage threshold. How powerful are the big truck-mounted water-cooled
I agree.
> lasers used for outdoor light shows? My guess is that that aircraft was
> illuminated by such a laser.
That would be much more likely, assuming the reports about retinal damage
are accurate. It's easy for an ophthalmologist to misdiagnose laser burns
if they are not an expert in laser burns especially if the patient comes
in expecting that to be the conclusion.
> The article also reports that handheld lasers are limited to 5
> milliwatts, while the green star-pointing lasers used in "astronomy
> research" can be 75 milliwatts. I seriously doubt that the amateur star
> pointers exceed 5 mw.
Higher power pointers cannot legally be sold to the general public in the
USA. But they are readily available if you know where to look.
> The article reports that in June 2004 the FAA's Civil Aerospace Medical
> Institute published a study titled "The Effects of Laser Illumination on
> Operational and Visual Performance of Pilots During Final Approach". (I
> haven't gotten this report yet.)
>
> Anyway, perhaps this study contains enough information to do the obvious
> analysis of received optical power -- can an ordinary handheld laser
> pointer really do much of anything to a airplane pilot? My instinct is
> that it cannot, never mind cause retinal burns.
Yes and no. Even a 5 mW pointer at thousands of feet can be bright enough to
be distracting at night. A slightly higher power laser (e.g., up say 100 mW)
may cause temporary flash-blindness and/or afterimages. Neither can do
permanent damage to vision though at long distances (unless the distraction
causes the plane to crash).
There is extensive discussion of this topic on alt.lasers . While certainly
not recommended, there are to the best of my knowledge, very few, if any,
substantiated reports of permanent eye damage from a 5 mW pointer even at point
blank range with multi-second duration, let alone a mementary flash from
thousands of feet away.
Theraputic/ophthalmic lasers used to treat retinal disorders operate at power
levels that are a minimum of 10 times higher and usually more like 50 to 100
times higher (or more) than 5 mW. They are coupled directly into the patient's
eye. And the ophthalmic surgions often have trouble getting a detectable
effect even at those high powers.
--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
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Note: These links are hopefully temporary until we can sort out the excessive
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Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.
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| | From: | Don Klipstein | | Subject: | Re: "Laser Safety in Sight" article in Aviation Week | | Date: | Mon, 17 Jan 2005 06:59:17 +0000 (UTC) |
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| In article ,
Joseph Gwinn wrote:
>On the matter of airplane pilots being blinded by laser light from the
>ground, the 10 January 2005 issue of Aviation Week & Space Technology
>magazine ran on page 42 a 1.5-page article on the subject, "Laser Safety
>in Sight". The article doesn't seem to be available online without
>getting a paid subscription, but most public libraries get Aviation
>Week, which is the Newsweek of the aircraft industry.
>
>The article reports that on 22 September 2004, a green light striking a
>Delta Air Lines flight approaching Salt Lake City caused a retinal burn
>to the first officer's eyes. The altitude, speed, and slant ranges were
>not reported, but one assumes that the aircraft was at least at a few
>thousand feet and traveling a few hundred miles per hour. I find it
>hard to believe that any handheld laser could have achieved the retinal
>damage threshold. How powerful are the big truck-mounted water-cooled
>lasers used for outdoor light shows? My guess is that that aircraft was
>illuminated by such a laser.
>
>The article also reports that handheld lasers are limited to 5
>milliwatts, while the green star-pointing lasers used in "astronomy
>research" can be 75 milliwatts. I seriously doubt that the amateur star
>pointers exceed 5 mw.
Green "laser pointers" as high as 190 milliwatts are sold!
Most green laser "pointers" of more than 50 milliwatts and some
around 50 milliwatts are larger items that take C-cell batteries and
somewhat resemble flashlights as opposed to being closer to the size of a
pen.
The cost of such beasts is generally a few to several hundred dollars.
>Anyway, perhaps this study contains enough information to do the obvious
>analysis of received optical power -- can an ordinary handheld laser
>pointer really do much of anything to a airplane pilot? My instinct is
>that it cannot, never mind cause retinal burns.
I really doubt retinal burns. In a rather extreme case, cause an
afterimage that still exists a couple or a few hours later. A 190 mW
laser pointer even if it has only .5 milliradian divergence would give
Class II exposure, supposedly safe to stare into for 1 second at 276
meters even if your pupil is 10 mm wide! A bigger problem is night vision
impairment over the next couple minutes.
>Joe Gwinn
- Don Klipstein (don@misty.com)
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| | From: | A. E. Siegman | | Subject: | Re: "Laser Safety in Sight" article in Aviation Week | | Date: | Mon, 17 Jan 2005 10:07:56 -0800 |
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| In article ,
don@manx.misty.com (Don Klipstein) wrote:
> I really doubt retinal burns . . . A bigger problem is night vision
> impairment over the next couple minutes.
Aka "dazzle", a term fairly widely used to describe visual impairment
effects, especially if deliberately produced. A truly serious problem,
both for deliberate military applications using higher power visual
lasers, and random amateur vandals using widely available civilian laser
pointers on motorists and pilots.
I've been told that if a dazzle attack is intense or sustained enough --
that is, if the initial pre-blink retinal overload is large enough or
the intense illumination source is still there after the initial blink,
causing further overload -- the result can be not only vision impairment
for multiple minutes, but disorientation and other physiological effects
resulting from psychological side effects of the visual impairment.
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| | From: | Don Klipstein | | Subject: | Re: "Laser Safety in Sight" article in Aviation Week | | Date: | Fri, 21 Jan 2005 03:11:43 +0000 (UTC) |
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| In , A. E. Siegman wrote:
>In article ,
> don@manx.misty.com (Don Klipstein) wrote:
>
>> I really doubt retinal burns . . . A bigger problem is night vision
>> impairment over the next couple minutes.
>
>Aka "dazzle", a term fairly widely used to describe visual impairment
>effects, especially if deliberately produced. A truly serious problem,
>both for deliberate military applications using higher power visual
>lasers, and random amateur vandals using widely available civilian laser
>pointers on motorists and pilots.
>
>I've been told that if a dazzle attack is intense or sustained enough --
>that is, if the initial pre-blink retinal overload is large enough or
>the intense illumination source is still there after the initial blink,
>causing further overload -- the result can be not only vision impairment
>for multiple minutes, but disorientation and other physiological effects
>resulting from psychological side effects of the visual impairment.
And it surely appears to me that a scenario this bad is an especially
unusually bad case even with 50-190 mW laser pointers, and nearly enough
impossible even just a couple miles away with a 5 mW one, even with 532 nm
wavelength...
How many incidents reported in the past month? Maybe 32? And how many
of those reported nothing much worse than detection of a laser flashing
the cockpit - maybe 31?
(Although I do agree with very harsh penalties for anyone proven to
shine a laser at an aircraft!)
- Don Klipstein (don@misty.com)
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| | From: | Dilettante | | Subject: | Re: "Laser Safety in Sight" article in Aviation Week | | Date: | Wed, 19 Jan 2005 11:24:10 -0500 |
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"A. E. Siegman" wrote
> Aka "dazzle", a term fairly widely used to describe visual impairment
> effects, especially if deliberately produced. A truly serious problem,
> both for deliberate military applications using higher power visual
> lasers, and random amateur vandals using widely available civilian laser
> pointers on motorists and pilots.
>
> I've been told that if a dazzle attack is intense or sustained enough --
> that is, if the initial pre-blink retinal overload is large enough or
> the intense illumination source is still there after the initial blink,
> causing further overload -- the result can be not only vision impairment
> for multiple minutes, but disorientation and other physiological effects
> resulting from psychological side effects of the visual impairment.
No need for a laser to suffer dangerous visual impairment, at night at
least.
A much more common condition is inflicted daily upon untold thousands of
motorists by morons whose cars are equipped with fancy powerful high beams
and who do turn switch them to low beams when necessary or required.
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| | From: | John Savard | | Subject: | Re: "Laser Safety in Sight" article in Aviation Week | | Date: | Mon, 17 Jan 2005 04:23:58 GMT |
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| On Sun, 16 Jan 2005 18:40:22 -0500, Joseph Gwinn
wrote, in part:
>The article also reports that handheld lasers are limited to 5
>milliwatts, while the green star-pointing lasers used in "astronomy
>research" can be 75 milliwatts. I seriously doubt that the amateur star
>pointers exceed 5 mw.
Observatories with telescopes using adaptive optics, of course, do have
much higher power lasers, which are used to excite oxygen atoms in the
upper atmosphere, producing pinpoint "artificial stars" (which actually
glow by means of the same mechanism as the aurora).
They, of course, do use their lasers responsibly, and they receive
notification of both approaching airplanes and of orbiting satellites
which also can be damaged by their lasers.
There was an article in Sky and Telescope about this a few years back.
I think their lasers are a bit more than 75 mW in power, though.
John Savard
http://home.ecn.ab.ca/~jsavard/index.html
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| | From: | Marc Reinig | | Subject: | Re: "Laser Safety in Sight" article in Aviation Week | | Date: | Mon, 17 Jan 2005 15:47:02 GMT |
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"John Savard" wrote in message
news:41eb3d53.301240@news.ecn.ab.ca...
> On Sun, 16 Jan 2005 18:40:22 -0500, Joseph Gwinn
> Observatories with telescopes using adaptive optics, of course, do have
> much higher power lasers, which are used to excite oxygen atoms in the
> upper atmosphere, producing pinpoint "artificial stars" (which actually
> glow by means of the same mechanism as the aurora).
The Lick observatory on Mt. Hamilton, California and the Keck observatory on
Mauna Kea, Hawaii use them. Actually, they excite sodium atoms in a band
that lies between 90 and 95 Km.
> They, of course, do use their lasers responsibly, and they receive
> notification of both approaching airplanes and of orbiting satellites
> which also can be damaged by their lasers.
In addition, they have a spotter outside at all times the laser is
operating.
> I think their lasers are a bit more than 75 mW in power, though.
Yup, over 10 Watts ;=)
Marc Reinig
UCO/Lick Observatory
Laboratory for Adaptive Optics
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