I'm going to "Laser" a pilot. [Archive]

Happy Dog

January 28th 05, 12:39 AM

Hello FBI surveillance software?

Anyway, I am now in possession of one brand new "Jasper" DPSS 5mw laser from
bigha.com. That's the same laser used in the recent media hyped incidents
at KTEB. I'm going to test the claims that pilots can be visually impaired
empirically. (Guess who the pilot is.) The weather is perfect for
his. -20 and clear. I plan to try it at distance of about 3500' which is
as close as anyone is likely to get to a landing plane. I happen to work
near a perfect stretch of parking lot (one of the best places in a busy
metropolis to land if you really have to) which is perfect for this. It's
very runway-like. I'm going to do three things:

1. Measure the size of the beam at a measured distance.

2. Look into the beam for about 500ms after conditioning my eyes to usual
night flying light levels.

3. Have a skilled pistol marksman (cop friend) try to accurately hold the
beam steady at a measured distance both free hand and with support and see
what the wiggle area is.

If anyone else can think of anything else they'd like to see tried (no, not
in *my* plane) please post it here.

This isn't meant to be a scientific experiment or to become information used
instead of any government research or guidelines. OK?

moo

Bob Gardner

January 28th 05, 02:46 AM

You're crazier than a bedbug. Hope you have a good source of slightly used
retinas.

Bob Gardner

"Happy Dog" > wrote in message
. ..
> Hello FBI surveillance software?
>
> Anyway, I am now in possession of one brand new "Jasper" DPSS 5mw laser
> from bigha.com. That's the same laser used in the recent media hyped
> incidents at KTEB. I'm going to test the claims that pilots can be
> visually impaired empirically. (Guess who the pilot is.) The weather is
> perfect for his. -20 and clear. I plan to try it at distance of about
> 3500' which is as close as anyone is likely to get to a landing plane. I
> happen to work near a perfect stretch of parking lot (one of the best
> places in a busy metropolis to land if you really have to) which is
> perfect for this. It's very runway-like. I'm going to do three things:
>
> 1. Measure the size of the beam at a measured distance.
>
> 2. Look into the beam for about 500ms after conditioning my eyes to usual
> night flying light levels.
>
> 3. Have a skilled pistol marksman (cop friend) try to accurately hold the
> beam steady at a measured distance both free hand and with support and see
> what the wiggle area is.
>
> If anyone else can think of anything else they'd like to see tried (no,
> not in *my* plane) please post it here.
>
> This isn't meant to be a scientific experiment or to become information
> used instead of any government research or guidelines. OK?
>
> moo
>

Happy Dog

January 28th 05, 03:09 AM

> "Happy Dog" > wrote in message

"Bob Gardner" > wrote in message news:W92dnXX_
>> Hello FBI surveillance software?
>>
>> Anyway, I am now in possession of one brand new "Jasper" DPSS 5mw laser
>> from bigha.com. That's the same laser used in the recent media hyped
>> incidents at KTEB. I'm going to test the claims that pilots can be
>> visually impaired empirically. (Guess who the pilot is.) The weather is
>> perfect for his. -20 and clear. I plan to try it at distance of about
>> 3500' which is as close as anyone is likely to get to a landing plane. I
>> happen to work near a perfect stretch of parking lot (one of the best
>> places in a busy metropolis to land if you really have to) which is
>> perfect for this. It's very runway-like. I'm going to do three things:
>>
>> 1. Measure the size of the beam at a measured distance.
>>
>> 2. Look into the beam for about 500ms after conditioning my eyes to
>> usual night flying light levels.
>>
>> 3. Have a skilled pistol marksman (cop friend) try to accurately hold
>> the beam steady at a measured distance both free hand and with support
>> and see what the wiggle area is.
>>
>> If anyone else can think of anything else they'd like to see tried (no,
>> not in *my* plane) please post it here.
>>
>> This isn't meant to be a scientific experiment or to become information
>> used instead of any government research or guidelines. OK?

> You're crazier than a bedbug. Hope you have a good source of slightly used
> retinas.

There's no risk. I'm calculating safety margins for exposure with the
assumption that the unit produces double its rated power. It'll still be
bright though.

moo

Rip

January 28th 05, 03:48 AM

Have fun. You'll see a fairly bright green flash, or halo, depending on
the aiming accuracy. Even with a 100 mW output, at 3500 feet any diode
laser output will have expanded to many feet in diameter. You do the
math. Retinal input will be on the order of 1 microwatt, assuming a 2
foot diameter beam at the reception distance.
This entire laser blinding scam is a load of hogwash. My HP35 calculator
had my initials burned into it's case with a 5 WATT argon laser about 30
years ago. You could put your hand into the beam at the output of the 1
meter long tube for several seconds before feeling any heat. Would I
look into the beam? Hell no. Would I look into the beam of a 100 mW
diode laser 3500 feet away? Hell yes. For as long as you'd like. $10 a
minute. Of course, if I was a United pilot, I'd be looking for any way
to recoup my pension...help, help, I've been shot in the eye by a
laser!!! Pay me, pay me! And if I was a media weasel, I wouldn't even
need an excuse to make up a story like this one.

Happy Dog wrote:
>>"Happy Dog" > wrote in message
>
>
> "Bob Gardner" > wrote in message news:W92dnXX_
>
>>>Hello FBI surveillance software?
>>>
>>>Anyway, I am now in possession of one brand new "Jasper" DPSS 5mw laser
>>>from bigha.com. That's the same laser used in the recent media hyped
>>>incidents at KTEB. I'm going to test the claims that pilots can be
>>>visually impaired empirically. (Guess who the pilot is.) The weather is
>>>perfect for his. -20 and clear. I plan to try it at distance of about
>>>3500' which is as close as anyone is likely to get to a landing plane. I
>>>happen to work near a perfect stretch of parking lot (one of the best
>>>places in a busy metropolis to land if you really have to) which is
>>>perfect for this. It's very runway-like. I'm going to do three things:
>>>
>>>1. Measure the size of the beam at a measured distance.
>>>
>>>2. Look into the beam for about 500ms after conditioning my eyes to
>>>usual night flying light levels.
>>>
>>>3. Have a skilled pistol marksman (cop friend) try to accurately hold
>>>the beam steady at a measured distance both free hand and with support
>>>and see what the wiggle area is.
>>>
>>>If anyone else can think of anything else they'd like to see tried (no,
>>>not in *my* plane) please post it here.
>>>
>>>This isn't meant to be a scientific experiment or to become information
>>>used instead of any government research or guidelines. OK?
>
>
>>You're crazier than a bedbug. Hope you have a good source of slightly used
>>retinas.
>
>
> There's no risk. I'm calculating safety margins for exposure with the
> assumption that the unit produces double its rated power. It'll still be
> bright though.
>
> moo
>
>

Rip

January 28th 05, 03:52 AM

Hey Happy Dog. Why don't you get a spot on "Myth Busters". I'll fly and
you aim the laser. Then we can swap positions and show the entire world
what a load of crap this entire laser thing is.

Happy Dog wrote:

> Hello FBI surveillance software?
>
> Anyway, I am now in possession of one brand new "Jasper" DPSS 5mw laser from
> bigha.com. That's the same laser used in the recent media hyped incidents
> at KTEB. I'm going to test the claims that pilots can be visually impaired
> empirically. (Guess who the pilot is.) The weather is perfect for
> his. -20 and clear. I plan to try it at distance of about 3500' which is
> as close as anyone is likely to get to a landing plane. I happen to work
> near a perfect stretch of parking lot (one of the best places in a busy
> metropolis to land if you really have to) which is perfect for this. It's
> very runway-like. I'm going to do three things:
>
> 1. Measure the size of the beam at a measured distance.
>
> 2. Look into the beam for about 500ms after conditioning my eyes to usual
> night flying light levels.
>
> 3. Have a skilled pistol marksman (cop friend) try to accurately hold the
> beam steady at a measured distance both free hand and with support and see
> what the wiggle area is.
>
> If anyone else can think of anything else they'd like to see tried (no, not
> in *my* plane) please post it here.
>
> This isn't meant to be a scientific experiment or to become information used
> instead of any government research or guidelines. OK?
>
> moo
>
>

Casey Wilson

January 28th 05, 03:54 AM

>
> If anyone else can think of anything else they'd like to see tried (no,
> not in *my* plane) please post it here.
>
> This isn't meant to be a scientific experiment or to become information
> used instead of any government research or guidelines. OK?
>
> moo

How about:
1. Acquire a standard optometrist eye chart.
[A television resolution chart would be a good substitute]
2. Before each exposure, determine visual acuity.
3. After each exposure, repeat acuity test
4. Start at a lower exposure duration and work up.
[This may require performing the test(s) on separate nights]
5. Do the whole thing during the day, facing away from the sun.
6. Chart your work

Hmmm, before step 1, check your medical insurance and have an
optometrist or opthomalogist do a retinal scan, before and after.

Doug

January 28th 05, 04:11 AM

Happy Dog wrote:

> ...
> This isn't meant to be a scientific experiment or to become information used
> instead of any government research or guidelines. OK?

I think you are missing the point Happy Dog... Frying eyeballs at 3500ft
with a 5mw device is not the question. I suspect the terrorists want to
verify their ability to point a higher powered, possibly useful weapon.

As usual, the news media is doing whatever they can to provide helpful
feedback.

Happy Dog

January 28th 05, 11:12 AM

"Rip" > wrote in message news:lG

> Hey Happy Dog. Why don't you get a spot on "Myth Busters". I'll fly and
> you aim the laser. Then we can swap positions and show the entire world
> what a load of crap this entire laser thing is.

I *hate* publicity. Knock yourslef out.

moo

Happy Dog

January 28th 05, 11:15 AM

"Casey Wilson" <N2310D @ gmail.com> wrote in

> 1. Acquire a standard optometrist eye chart.
> [A television resolution chart would be a good substitute]
> 2. Before each exposure, determine visual acuity.
> 3. After each exposure, repeat acuity test
> 4. Start at a lower exposure duration and work up.
> [This may require performing the test(s) on separate nights]
> 5. Do the whole thing during the day, facing away from the sun.
> 6. Chart your work
>
> Hmmm, before step 1, check your medical insurance and have an
> optometrist or opthomalogist do a retinal scan, before and after.

Apart from the retinal scan, pointless. The claim is that tiny lasers can
blind pilots. It's bull****. There isn't even a valid theory behind it.
My work is just entertainment.

moo

10Squared

January 28th 05, 11:53 AM

Happy Dog wrote:

> "Casey Wilson" <N2310D @ gmail.com> wrote in

> Apart from the retinal scan, pointless. The claim is that tiny lasers can
> blind pilots. It's bull****. There isn't even a valid theory behind it.
> My work is just entertainment.
>
> moo

Although I agree that it is impossible to hold a laser on a sufficiently
small area at the distances described (a 1 degree fluctuation causing a ca.
90 ft. movement at 1 mile if my math is correct), there is valid theory
behind it. Maximum permissible exposure when looking into a laser beam is a
function of exposure time.

For wavelengths of 400 nm to 1.4 um: [1]

t = 1 ns to 2x10^-5 s MPE = 0.0005 mJ cm^-2
t = 2x10^-5 s to 10 s MPE = 1.8xt^(3/4) mJ cm^-2
t > 10 s MPE = 10 mJ cm^-2

Laser device in question has a rated power of 5 mW.
1 W = 1 J/s
5 mW = 5 mJ/s

Assuming under the worst case the beam spread results in a beam no bigger
than 1 square centimeter (and there are 2.54 centimeters in an inch), the
exposure NEVER exceeds the MPE, even for very long exposure times. In
reality the beam spread is much greater. A device I tested has a beam
spread of over 2 inches at 50 feet.

How accurately must one be to hold the 1 cm beam on target at the target
distance? Assuming a distance of 1 km, a 1 cm movement is equivalent to an
angular displacement of:

tan a = 1 cm / 1 km = 1 x 10^-2 / 1 x 10^3 = 1 x 10^-5
a =~ .00001 radians =~ 20 arc seconds

So, the whole thing doesn't wash. The power is insufficient, the beam spread
is too great, and the required pointing accuracy is too high.

[1] Jurgen R. Meyer-Arendt, M.D., "Introduction to Classical and Modern
Optics", 2nd ed.

Happy Dog

January 28th 05, 12:11 PM

"Doug" > wrote in message

>> This isn't meant to be a scientific experiment or to become information
>> used instead of any government research or guidelines. OK?
>
> I think you are missing the point Happy Dog... Frying eyeballs at 3500ft
> with a 5mw device is not the question.

That's the claim.

> I suspect the terrorists want to verify their ability to point a higher
> powered, possibly useful weapon.

Like a cheap hunting rifle? You "suspect"? Any evidence that "the
terrorists want to verify their ability to point a higher powered, possibly
useful weapon"? "The terrorists"? Are you stupid? Clinically paranoid?
Pick one. GA has been bent over and ****ed for the last four years for
absolutely no defensible reason. The laser incidents are a perfect example.
You got some evidence to the contrary? Produce or shut up. Homeland
insecurity doesn't give **** one about us beyond Boyer. (You a member?) In
the meantime:

The whole thing is crap. It's homeopathic psoriasis-curing crap.
Multi-level marketing crap. Girls waiting for your call crap. Flying
yourself is cheaper than driving crap. Flying yourself is cheaper than
flying commercial crap. PPL for 3000.00 crap. ATP and a career for
10,000.00 crap. Flight schools that actually make money that promoting the
previous crap crap. You can get insurance to fly your GIII anywhere for
less than first class tickets for you and your family every week crap.
Parachutes that statistically change the GA accident rate crap. Parachutes
that won't save you better than a Vso, Vg, *whatever* crash at night crap.
Twin eninges will save your life crap. Twin engines will, engine failure
over cold water, (holy christ, *that's* a sobering thought) due to the
statistical improbablility of having to swim not make it worth it to own one
if you can afford it crap. Pilot error crap. Investigator error crap.
Ground crew fueling ****up crap. Fuel transfer mismanagement crap. Ten, or
twenty, tank drains will save you crap. Somebody *elses* fault crap. I
would have put it down on the fairway crap. I have no opinion about that
crap. Gear up landing because ATC rushed me crap. Night flying (over 100
hrs) isn't IFR flying crap. Alternative to regular exercise "xxx" to get
your mill to TBO crap. Graphic in-cockpit display of IFR approaches will
save your life crap. Navigating NYC Terminal Air Space with just a map
crap. Flying is safer than driving your car crap. Planes, boats and
hookers (guys OR girls) are a good investment crap.

ARRRGHHHH. NOW you've done it! From sci.physics, Uncle raileth:

It is the worst kind of pandering magnetic hernia truss multi- level
marketing to make you rich beyond your wildest dreams by tomorrow without so
much as a lick of personal inconvenience crap. It is Lotto crap, Publisher's
Clearinghouse crap, Home Shopping Network crap, infomercial crap, Bre-X
crap, hollow Earth crap, flat Earth crap, Heaven's Gate crap, Chariots of
the Gods crap, quartz crystal crap, teleevangelical crap, thinner thighs in
30 days crap, other-ablement crap, Virgin Mary on a taco crap, Elvis on a
taco crap, War on Drugs crap, War on Poverty crap, night basketball crap,
eat oat bran crap, breast enlargement cream crap, buy the Brooklyn Bridge at
only a tiny fraction of its true value crap, 1000-year old ginseng crap,
5000 yogic floaters to cleanse the world crap, free energy crap, anti-
gravity crap, hot young girls waiting for your call crap, psychics hot line
crap, never change your engine oil again crap, interpret your dreams crap,
sure-fire horse betting crap, Superman squeezing a lump of coal into a blue
white and perfect fully faceted 290 carat diamond crap...
.... Peace Dividend crap, Bosnian/Somali/Northern Ireland/Iraqi pacification
crap, peace in our time crap, Pacem in Terris crap, Limits to Growth crap,
Whip Inflation Now crap, I am not a crook crap, nukular engineer crap, I
didn't inhale crap, Health Care Crisis crap, Department of Energy crap,
marijuana will kill you crap, chastity crap, tobacco isn't addictive crap,
burning tobacco isn't carcinogenic crap, children kidnapped over the
Internet and sold into hebephile pornography crap...

....MBA crap, human factors engineering crap, social engineering crap,
Project Head Start crap, thousand points of light crap, compassion crap,
nurturance crap, sensitivity counseling crap, Special Olympics crap,
learning disablement crap, Affirmative Action/Equal Opportunity/diversity
crap, multiculturalism crap, multilingualism crap, Kwanzaa crap, Days of
Rage crap, Nobel Prize in Literature crap, automotive airbags crap, commuter
lane crap, the E*L*E*C*T*R*I*C car crap, recycled post-consumer waste crap,
low volume flush toilet crap, fuel from biomass crap...

....Workers' Paradise crap, Democratic Republic of [you name it] crap, New
Soviet Man crap, Save the Earth crap, Furbish lousewort crap, clothe animals
to hide their genitalia crap, N-rays crap, Krebiozen crap, amygdalin crap,
smart drugs crap, coffee enemas to cure cancer crap, cosmic consciousness
crap, orgone energy crap, aura crap, astral plane crap, astrology crap,
ouija board crap...

Crap, crap, crap.

LOVE Usenet!

moo

[email protected]

January 28th 05, 01:12 PM

What a load of crap.

[email protected]

January 28th 05, 01:37 PM

Dear Mr. H. Dog,

There is some debate wheter or not these lasers do any harm.
Another rumour is that fast spinning objects are invulnerable to high
power lasers.
Well, combine those two.
You are going to use a low power one so the spinning does have to be
very fast.
I think the roll rate of a plane will be enough.
So, roll your plane as fast as possible on final approach and see what
happens(Do not forget to level wings just before touch down)
Present your findings to the FAA.
Maybe they make it a rule that everybody has to roll their planes on
final because it is much safer in case of a terrorist attack with laser
pointers.

-Kees

Doug

January 28th 05, 01:58 PM

Happy Dog wrote:
>...
> Are you stupid? Clinically paranoid?
> Pick one. GA has been bent over and ****ed for the last four years for
> absolutely no defensible reason.
> ...six thousand word pointless rant removed...

Dear M. Happy Dog,

Re your rather sharp concerns about paranoia: As soon as practicable,
take a look at www.buying-medication.com/Prosac.htm. Also, you should
equip yourself with a tin foil hat which should increase your sculls
albedo in addition to protecting you from FAA/CIA scanning.

Larry Dighera

January 28th 05, 02:29 PM

On Fri, 28 Jan 2005 07:11:33 -0500, "Happy Dog"
> wrote in
>::

>The whole thing is crap.

You're obviously THE crap expert, and a credit to the public image of
airmen everywhere. :-) But then, I wouldn't expect anything less from
an anonymous usenet poster.

Larry Dighera

January 28th 05, 02:59 PM

On Fri, 28 Jan 2005 11:53:03 +0000, 10Squared >
wrote in >::

>Laser device in question has a rated power of 5 mW.

Actually, some are available with over 10 times that power:
http://www.wickedlasers.com/products.php

However, as you assert, they are probably still incapable of
inflicting retinal damage at the distances involved when aimed at an
aircraft in flight.

Casey Wilson

January 28th 05, 03:40 PM

"Happy Dog" > wrote in message
. ..
> "Casey Wilson" <N2310D @ gmail.com> wrote in
>
>> 1. Acquire a standard optometrist eye chart.
>> [A television resolution chart would be a good substitute]
>> 2. Before each exposure, determine visual acuity.
>> 3. After each exposure, repeat acuity test
>> 4. Start at a lower exposure duration and work up.
>> [This may require performing the test(s) on separate nights]
>> 5. Do the whole thing during the day, facing away from the sun.
>> 6. Chart your work
>>
>> Hmmm, before step 1, check your medical insurance and have an
>> optometrist or opthomalogist do a retinal scan, before and after.
>
>
> Apart from the retinal scan, pointless. The claim is that tiny lasers can
> blind pilots. It's bull****. There isn't even a valid theory behind it.
> My work is just entertainment.

Truth be told, I agree that the hysteria regarding the lasers, as you
succinctly put it in a later post, is a load of it. My suggestions in the
list were to give your test some data points that, while not scientific,
would show trends, if any. What you end up with may be publishable.

10Squared

January 28th 05, 11:35 PM

Larry Dighera wrote:

> On Fri, 28 Jan 2005 11:53:03 +0000, 10Squared >
> wrote in >::
>
>>Laser device in question has a rated power of 5 mW.
>
> Actually, some are available with over 10 times that power:
> http://www.wickedlasers.com/products.php
>
> However, as you assert, they are probably still incapable of
> inflicting retinal damage at the distances involved when aimed at an
> aircraft in flight.

OK, let's see what happens with their most wicked laser. I see the Extreme
Phoenix with a power rating of 500mW. The quoted beam divergence is <1.2
mrad. Assuming a distance of 1 km,

a = 1.2 mrad
tan a = x / 1 * 10^3
x = 10^3 * m * x tan a
tan a =~ a
x = 1.2 * 10^3 * 10^-3 * m = 1.2 meters

To be conservative, let's use the beam divergence of only .5 mrad, or .5
meters at 1 km:

..5 m = 50 cm
p = 500 mW / (3.141 * 25 * 25 * cm^2)

Your 500 mW laser has a power of about .25 mW/cm^2 at 1 km. Again, much less
than the MPE for constant exposure. That brings up another point: Who is
going to stare at a laser? Brief exposure is uncomfortable and will cause
you to look away quickly, so MPE equation #2 is probably the one that
applies.

Happy Dog

January 28th 05, 11:41 PM

:)

moo

> wrote in message
oups.com...
> Dear Mr. H. Dog,
>
> There is some debate wheter or not these lasers do any harm.
> Another rumour is that fast spinning objects are invulnerable to high
> power lasers.
> Well, combine those two.
> You are going to use a low power one so the spinning does have to be
> very fast.
> I think the roll rate of a plane will be enough.
> So, roll your plane as fast as possible on final approach and see what
> happens(Do not forget to level wings just before touch down)
> Present your findings to the FAA.
> Maybe they make it a rule that everybody has to roll their planes on
> final because it is much safer in case of a terrorist attack with laser
> pointers.
>
> -Kees
>

Happy Dog

January 28th 05, 11:42 PM

"Larry Dighera" >
> > wrote in
> >::
>
>>The whole thing is crap.
>
> You're obviously THE crap expert, and a credit to the public image of
> airmen everywhere. :-) But then, I wouldn't expect anything less from
> an anonymous usenet poster.

Hardly anonymous. I post from my ISP. HD is a registered name. It's even
on my Visa.

moo

Happy Dog

January 28th 05, 11:44 PM

"Larry Dighera" > wrote in message
>>Laser device in question has a rated power of 5 mW.
>
> Actually, some are available with over 10 times that power:
> http://www.wickedlasers.com/products.php
>
> However, as you assert, they are probably still incapable of
> inflicting retinal damage at the distances involved when aimed at an
> aircraft in flight.

As I've said before, I have small NdYAG lasers that produce 3 watts (600x)
and Gas Ion ones that produce over twenty watts. But that's not what the
hype is about.

moo

Larry Dighera

January 29th 05, 12:13 AM

On Fri, 28 Jan 2005 18:44:25 -0500, "Happy Dog"
> wrote in
>::

>"Larry Dighera" > wrote in message
>>>Laser device in question has a rated power of 5 mW.
>>
>> Actually, some are available with over 10 times that power:
>> http://www.wickedlasers.com/products.php
>>
>> However, as you assert, they are probably still incapable of
>> inflicting retinal damage at the distances involved when aimed at an
>> aircraft in flight.
>
>As I've said before, I have small NdYAG lasers that produce 3 watts (600x)
>and Gas Ion ones that produce over twenty watts.

But those are not small handheld laser pointers, right?

>But that's not what the hype is about.

Right. So why mention them?

The US government possesses far larger lasers than you ever will, but
that too is not germane to the discussion, unlike those in the link I
provided.

Happy Dog

January 29th 05, 12:51 AM

"Larry Dighera" > wrote in message
...
> On Fri, 28 Jan 2005 18:44:25 -0500, "Happy Dog"
> > wrote in
> >::
>
>>"Larry Dighera" > wrote in message
>>>>Laser device in question has a rated power of 5 mW.
>>>
>>> Actually, some are available with over 10 times that power:
>>> http://www.wickedlasers.com/products.php
>>>
>>> However, as you assert, they are probably still incapable of
>>> inflicting retinal damage at the distances involved when aimed at an
>>> aircraft in flight.
>>
>>As I've said before, I have small NdYAG lasers that produce 3 watts (600x)
>>and Gas Ion ones that produce over twenty watts.
>
> But those are not small handheld laser pointers, right?
>
>>But that's not what the hype is about.
>
> Right. So why mention them?
>
> The US government possesses far larger lasers than you ever will, but
> that too is not germane to the discussion, unlike those in the link I
> provided.
>
>

Larry Dighera

January 29th 05, 03:11 AM

On Fri, 28 Jan 2005 23:35:34 +0000, 10Squared >
wrote in >::

>Larry Dighera wrote:
>
>> On Fri, 28 Jan 2005 11:53:03 +0000, 10Squared >
>> wrote in >::
>>
>>>Laser device in question has a rated power of 5 mW.
>>
>> Actually, some are available with over 10 times that power:
>> http://www.wickedlasers.com/products.php
>>
>> However, as you assert, they are probably still incapable of
>> inflicting retinal damage at the distances involved when aimed at an
>> aircraft in flight.
>
>OK, let's see what happens with their most wicked laser. I see the Extreme
>Phoenix with a power rating of 500mW.

Just to be accurate, I believe the Wicked laser diode is RATED at
500mW, but the claimed output is 70 to 80 mW, IIRC.

>The quoted beam divergence is <1.2 mrad. Assuming a distance of 1 km,
>
>a = 1.2 mrad
>tan a = x / 1 * 10^3
>x = 10^3 * m * x tan a
>tan a =~ a
>x = 1.2 * 10^3 * 10^-3 * m = 1.2 meters
>
>To be conservative, let's use the beam divergence of only .5 mrad, or .5
>meters at 1 km:
>
>.5 m = 50 cm
>p = 500 mW / (3.141 * 25 * 25 * cm^2)
>
>Your 500 mW laser has a power of about .25 mW/cm^2 at 1 km. Again, much less
>than the MPE for constant exposure.

Intuitively, I didn't question that, but thank you for the formulae.

>That brings up another point: Who is going to stare at a laser? Brief
>exposure is uncomfortable and will cause you to look away quickly, so
>MPE equation #2 is probably the one that applies.

So you're saying that closing one's eyes or looking away is reflexive.
What length of time would you estimate it takes for that reflex to
occurr?

What magnitude of laser power would you estimate to be required to
cause retinal damage at say 1 mile for what period of time?

Casey Wilson

January 29th 05, 03:56 AM

"Larry Dighera" > wrote in message
...

<<<< Big Snip!! >>>>

>
> What magnitude of laser power would you estimate to be required to
> cause retinal damage at say 1 mile for what period of time?
>
If I may change to a different laser wavelength with a conforming
lens, a 1 megawatt laser will cause nearly instantaneous, and irreversible,
damage at ranges beyond one mile.
I agree with Happy Dog. The toys being bandied about here, and what
are available on the consumer market, are virtually harmless. On the other
hand, a NdYAG for example, is NOT in the visible spectrum and you wouldn't
know to look away until that blurry spot appeared in your visual field. Same
with CO2 and a host of other weapons grade gadgets.
My work with lasers, admitedly years, decades ago, made me
hyper-concious of the dangers. Especially having to sit through a
comprehensive retinal scan and image record every three months, just to make
sure I hadn't screwed up. Which in my lab was very difficult -- it two
people with separate keys on opposite sides of the room and a 3-second
klaxon to turn the gadgets on. I don't even like to see laser pointers used
in darkened rooms, even though I would testify to their safety.

AES

January 29th 05, 04:21 AM

In article >,
Larry Dighera > wrote:

>
> What magnitude of laser power would you estimate to be required to
> cause retinal damage at say 1 mile for what period of time?

The problem is not damage, it's "dazzle" -- having what seems to be a
_very_ bright light more or less in the center of your field of view and
coming straight into your eyes.

Yes, you blink, or look away -- but after you open your eyes the bright
incoming light may still be there, very close in angle or position to
the terrain or the instruments you have to look at, so you can't really
easily block it. Even with the laser positioned somewhat off to the
side there may be a lot of bright scatter from dirt or scratches on the
windshield, very similar to the situation of driving a car with a dirty
or scratched windshield (or just with aging eyeballs) looking into the
bright headlights of oncoming cars. And, any night vision adaptation
you may have had is gone (night vision can be wiped out considerably
faster than it can be restored).

All of these effects can be produced at light intensities way, way below
the level that produces any permanent damage to the retina. Though I'm
no expert on this subject, I have also been told that sustained exposure
to this kind of illumination in a situation where you can't just "turn
it off" and where the light levels, although below permanent damage, are
well above what leads to you to blink, and especially if they occur in
stressful situations with demanding performance requirements, can
rapidly lead to various kinds of psychological distress.

Happy Dog

January 29th 05, 04:26 AM

"10Squared" > wrote in message

> OK, let's see what happens with their most wicked laser. I see the Extreme
> Phoenix with a power rating of 500mW.

Their most powerful one is rated at less than 100mw. They claim to use a
500mw diode but the actual output is around 90mw max.

> Your 500 mW laser has a power of about .25 mW/cm^2 at 1 km.

Make that .05mw.

moo

Happy Dog

January 29th 05, 04:29 AM

"Casey Wilson" <N2310D @ gmail.com> wrote in

> If I may change to a different laser wavelength with a conforming
> lens, a 1 megawatt laser will cause nearly instantaneous, and
> irreversible, damage at ranges beyond one mile.
> I agree with Happy Dog. The toys being bandied about here, and what
> are available on the consumer market, are virtually harmless. On the other
> hand, a NdYAG for example, is NOT in the visible spectrum and you wouldn't
> know to look away until that blurry spot appeared in your visual field.
> Same with CO2 and a host of other weapons grade gadgets.

NdYAGs are available in visible wavelengths. As for UV or IR lasers, how
would you aim them?

moo

Happy Dog

January 29th 05, 04:48 AM

"AES" > wrote in message

> Yes, you blink, or look away -- but after you open your eyes the bright
> incoming light may still be there, very close in angle or position to
> the terrain or the instruments you have to look at, so you can't really
> easily block it.

Missed approach. Problem solved.

> All of these effects can be produced at light intensities way, way below
> the level that produces any permanent damage to the retina. Though I'm
> no expert on this subject, I have also been told that sustained exposure
> to this kind of illumination in a situation where you can't just "turn
> it off" and where the light levels, although below permanent damage, are
> well above what leads to you to blink, and especially if they occur in
> stressful situations with demanding performance requirements, can
> rapidly lead to various kinds of psychological distress.

Did an "expert" tell you this?

moo

Larry Dighera

January 29th 05, 12:27 PM

On Sat, 29 Jan 2005 03:56:23 GMT, "Casey Wilson" <N2310D @ gmail.com>
wrote in <HPDKd.2876$RI.2060@trnddc06>::

>
>"Larry Dighera" > wrote in message
...
>
><<<< Big Snip!! >>>>
>
>>
>> What magnitude of laser power would you estimate to be required to
>> cause retinal damage at say 1 mile for what period of time?
>>
> If I may change to a different laser wavelength with a conforming
>lens, a 1 megawatt laser will cause nearly instantaneous, and irreversible,
>damage at ranges beyond one mile.

So you figure that 1-megawatt is the MINIMUM power necessary? Given
the fact that the majority of homes in the US are served by a
24-kilowatt (2.4% of a megawatt) electrical service, it's not likely
that any retinal damage is possible without browing out half a
neighborhood. :-)

10Squared

January 29th 05, 02:43 PM

George Patterson wrote:

> Happy Dog wrote:
>>
>> As for UV or IR lasers, how would you aim them?
>
> Possibly by "piggybacking" them to one of your "toy" lasers such that both
> hit the same spot.

And there you go. We have gone from a claim that laser pointers can cause
retinal damage of pilots in aircraft several thousand feet distant, and
bring down airliners in the process, to a claim that laser pointers can be
used as sighting devices for a CO2 or other high power laser with an
invisible beam. Why would you give yourself away with a visible beam when
you can use a high powered optical sight? You don't have windage or gravity
to deal with. Should we mitigate the risk posed by high power invisible
laser beams? How should we mitigate the risk?

George Patterson

January 29th 05, 04:46 PM

Happy Dog wrote:
>
> As for UV or IR lasers, how would you aim them?

Possibly by "piggybacking" them to one of your "toy" lasers such that both hit
the same spot.

George Patterson
He who marries for money earns every penny of it.

AES

January 29th 05, 05:28 PM

In article >,
"Happy Dog" > wrote:

> "AES" > wrote in message
>
> > > All of these effects can be produced at light intensities way, way below
> > the level that produces any permanent damage to the retina. Though I'm
> > no expert on this subject, I have also been told that sustained exposure
> > to this kind of illumination in a situation where you can't just "turn
> > it off" and where the light levels, although below permanent damage, are
> > well above what leads to you to blink, and especially if they occur in
> > stressful situations with demanding performance requirements, can
> > rapidly lead to various kinds of psychological distress.
>
> Did an "expert" tell you this?

My final (and excessively lengthy) sentence above is a summary of what I
recall hearing as a participant in a meeting where a group of civilian
laser experts and U.S. Air Force personnel discussed the military uses
of laser dazzling techniques against pilots in hostile situations
(including mention of some real-world examples where this technique had
been employed).

This was some time back, and the discussion of the "psychological
distress" aspects was, as I best recall, brief with no detailed examples
being presented, which is why I started this particular sentence with a
disclaimer.

If you in turn have evidence to contradict this, or to demonstrate that
I've made errors in this particular sentence, I'd be glad to hear it,
and I suspect others on this NG might be interested also.

Happy Dog

January 29th 05, 09:18 PM

"AES" > wrote in message news:siegman-B29138.
> "Happy Dog" > wrote:
>
>> "AES" > wrote in message
>>
>> > > All of these effects can be produced at light intensities way, way
>> > > below
>> > the level that produces any permanent damage to the retina. Though I'm
>> > no expert on this subject, I have also been told that sustained
>> > exposure
>> > to this kind of illumination in a situation where you can't just "turn
>> > it off" and where the light levels, although below permanent damage,
>> > are
>> > well above what leads to you to blink, and especially if they occur in
>> > stressful situations with demanding performance requirements, can
>> > rapidly lead to various kinds of psychological distress.

> If you in turn have evidence to contradict this, or to demonstrate that
> I've made errors in this particular sentence, I'd be glad to hear it,
> and I suspect others on this NG might be interested also.

Not to contradict it, since the term "psychological distress" is impossibly
vague. It was that phrase that made me wonder what kind of "expert"
muttered it.

moo

10Squared

January 29th 05, 10:12 PM

Legrande Harris wrote:

> Wouldn't wearing polarized sunglasses just about completely eliminate
> the problem of lasers aimed at pilots eyes? The polarization should
> completely stop the laser light from coming through the glasses.

Using an LED laser pointer and a pair of polarized glasses I tested your
idea. There is attenuation of the beam that is dependent on the orientation
of the pointer. So, the attenuation depends on how the person on the other
end is holding the pointer.

10Squared

January 29th 05, 10:12 PM

Legrande Harris

January 30th 05, 12:11 AM

Wouldn't wearing polarized sunglasses just about completely eliminate
the problem of lasers aimed at pilots eyes? The polarization should
completely stop the laser light from coming through the glasses.

Larry Dighera

January 30th 05, 02:04 AM

On Sat, 29 Jan 2005 22:12:40 +0000, 10Squared >
wrote in >::

>Legrande Harris wrote:
>
>> Wouldn't wearing polarized sunglasses just about completely eliminate
>> the problem of lasers aimed at pilots eyes? The polarization should
>> completely stop the laser light from coming through the glasses.
>
>Using an LED laser pointer and a pair of polarized glasses I tested your
>idea. There is attenuation of the beam that is dependent on the orientation
>of the pointer. So, the attenuation depends on how the person on the other
>end is holding the pointer.

If the aircraft windscreen were silvered so that it would be
reflective perhaps it would help reduce the laser's effect.

But these methods are going to reduce the pilot's visual acuity at
night.

George Patterson

January 30th 05, 03:56 AM

10Squared wrote:
>
> Why would you give yourself away with a visible beam when
> you can use a high powered optical sight?

Ever tried to use one at night?

George Patterson
He who marries for money earns every penny of it.

Happy Dog

January 30th 05, 08:38 AM

"George Patterson" > \> 10Squared wrote:
>>
>> Why would you give yourself away with a visible beam when
>> you can use a high powered optical sight?
>
> Ever tried to use one at night?

Yeah. The whole thing is absurd. If a pilot was blinded by UV laser, you
can bet that commercial passenger jets would be equipped with UV detectors
(mundane technology) and pilots would be wearing protective goggles on
approach (again, commonly available). The whole idea is silly, from a
terrorism POV.

moo

10Squared

January 30th 05, 11:56 AM

George Patterson wrote:

> 10Squared wrote:
>>
>> Why would you give yourself away with a visible beam when
>> you can use a high powered optical sight?
>
> Ever tried to use one at night?

Well, since this fantasy involves well-equipped evildoers they have night
vision scopes on their invisible ray guns.

Andrew Sarangan

January 30th 05, 03:57 PM

What exactly is an LED Laser pointer? It is an LED or a laser; it can't be
both.

Not all lasers are polarized. You can also get unpolarized laser emission.

10Squared > wrote in
:

> Legrande Harris wrote:
>
>> Wouldn't wearing polarized sunglasses just about completely eliminate
>> the problem of lasers aimed at pilots eyes? The polarization should
>> completely stop the laser light from coming through the glasses.
>
> Using an LED laser pointer and a pair of polarized glasses I tested
> your idea. There is attenuation of the beam that is dependent on the
> orientation of the pointer. So, the attenuation depends on how the
> person on the other end is holding the pointer.

Don Tuite

January 30th 05, 04:33 PM

On Sun, 30 Jan 2005 11:56:49 +0000, 10Squared >
wrote:

>George Patterson wrote:
>
>> 10Squared wrote:
>>>
>>> Why would you give yourself away with a visible beam when
>>> you can use a high powered optical sight?
>>
>> Ever tried to use one at night?
>
>Well, since this fantasy involves well-equipped evildoers they have night
>vision scopes on their invisible ray guns.

If they're going to use optical scopes and invisible rays, why does it
have to be at night?

Don

10Squared

January 31st 05, 04:39 PM

Legrande Harris wrote:

> In article >,
> 10Squared > wrote:
>
>> Legrande Harris wrote:
>>
>> > Wouldn't wearing polarized sunglasses just about completely eliminate
>> > the problem of lasers aimed at pilots eyes? The polarization should
>> > completely stop the laser light from coming through the glasses.
>>
>> Using an LED laser pointer and a pair of polarized glasses I tested your
>> idea. There is attenuation of the beam that is dependent on the
>> orientation of the pointer. So, the attenuation depends on how the person
>> on the other end is holding the pointer.
>
> How precisely does the pointer have to be aligned? If it is off by 5
> degrees does the laser get through?

Yes, the attenuation was proportional to the amount of rotation from 0-90
degrees. In short, it's nothing you could count on to protect you.

Legrande Harris

January 31st 05, 05:12 PM

In article >,
10Squared > wrote:

> Legrande Harris wrote:
>
> > Wouldn't wearing polarized sunglasses just about completely eliminate
> > the problem of lasers aimed at pilots eyes? The polarization should
> > completely stop the laser light from coming through the glasses.
>
> Using an LED laser pointer and a pair of polarized glasses I tested your
> idea. There is attenuation of the beam that is dependent on the orientation
> of the pointer. So, the attenuation depends on how the person on the other
> end is holding the pointer.

How precisely does the pointer have to be aligned? If it is off by 5
degrees does the laser get through?

Legrande Harris

January 31st 05, 05:29 PM

In article >,
Andrew Sarangan > wrote:

> Not all lasers are polarized. You can also get unpolarized laser emission.

Yes, but aren't the upolarized lasers quite weak? My only real
experience with lasers was messing around with them in college physics
classes and all the different laser beams could be blocked quite easily
with polarized glass.

Obviously if the laser is strong enough to burn through the glass then
it won't work, but those lasers are not readily available :)

LG

AES

January 31st 05, 07:06 PM

IF the laser is (linearly) polarized to a fairly high degree (not too
difficult in practice),

and IF the pilot is wearing polarized sunglasses (readily available),

and IF the laser is physically rotated (about its long axis) so that its
direction of polarization exactly matches the linear polarization that
is blocked by the polarized sunglasses (has to be done carefully and
deliberately, to within a few degrees),

and IF there is no deliberate or accidental conversion of the laser
beam's polarization between the laser and the sunglasses (e.g.,
deliberate conversion to circular polarization, effects of scattering,
birefringence in stressed windshield),

THEN only a small amount of the laser light will get through.

Rotate the laser about its axis by 45 degrees in either direction and
half the light will get through (which in terms of "dazzle" effects
means most of it gets through). Between 45 and 135 degree rotation in
either direction, more than half and up to 100% gets through.

The polarization direction of ordinary polarized sunglasses is set in a
certain direction because that's best for minimizing glare from
shallow-angle reflections. Any minimally competent bad guy could
therefore defeat their protection.

[And just for side interest, the LCD screen on my expensive 21" Sun
monitor is polarized exactly wrong, such that you simply can't use it
while wearing polarized sunglasses. The Sun engineers who designed it
knew computers, but not optics. Most laptop screens are polarized at 45
degrees; if you wear polarized sunglasses while using them you block
half the light, which your eye or brain adapts to and you don't even
notice it. Try tilting your head left and right while doing this some
time. I've observed that some of the credit card and signature screens
in California 7/11's also seem to be polarized exactly wrong for
polarized sunglasses.]

[email protected]

January 31st 05, 09:37 PM

Those of us on alt.lasers are having several discussions of this same
topic. Our take is that this is a lot of nonsense, possibly with some
ulterior motive on the part of the government. One person wrote a
letter to one of the government agencies involved, and posted the
reply. The government stands by their story that a doctor (notice, one
doctor) found retinal burns on the pilots he examined (laser source
unknown). We still think it's a bunch of nonsense (several of us have
worked around a lot of lasers, and I, for one, have a degree in Laser
Electro-Optic Technology).

[email protected]

January 31st 05, 09:47 PM

"So you're saying that closing one's eyes or looking away is
reflexive."

Yes, it is called, "Aversion Reflex."

"What length of time would you estimate it takes for that reflex to
occurr? "

About 250 milliseconds.
BTW, the aversion reflex only works in the visible spectrum.

Larry Dighera

January 31st 05, 11:08 PM

On 31 Jan 2005 13:47:11 -0800, wrote in
. com>::

>"So you're saying that closing one's eyes or looking away is
>reflexive."
>
>Yes, it is called, "Aversion Reflex."
>
>"What length of time would you estimate it takes for that reflex to
>occurr? "
>
>About 250 milliseconds.
>BTW, the aversion reflex only works in the visible spectrum.

Thank you for the information.

Larry Dighera

January 31st 05, 11:20 PM

On 31 Jan 2005 13:37:52 -0800, wrote in
. com>::

>Those of us on alt.lasers are having several discussions of this same
>topic. Our take is that this is a lot of nonsense, possibly with some
>ulterior motive on the part of the government. One person wrote a
>letter to one of the government agencies involved, and posted the
>reply. The government stands by their story that a doctor (notice, one
>doctor) found retinal burns on the pilots he examined (laser source
>unknown). We still think it's a bunch of nonsense (several of us have
>worked around a lot of lasers, and I, for one, have a degree in Laser
>Electro-Optic Technology).

Are you referring to the Delta pilot in the story at the link below,
or the military pilots?

http://www.washtimes.com/national/20040928-111356-3924r.htm

Happy Dog

January 31st 05, 11:51 PM

> wrote in message

> Those of us on alt.lasers are having several discussions of this same
> topic. Our take is that this is a lot of nonsense, possibly with some
> ulterior motive on the part of the government. One person wrote a
> letter to one of the government agencies involved, and posted the
> reply. The government stands by their story that a doctor (notice, one
> doctor) found retinal burns on the pilots he examined (laser source
> unknown). We still think it's a bunch of nonsense (several of us have
> worked around a lot of lasers, and I, for one, have a degree in Laser
> Electro-Optic Technology).

"Pilots"? More than one? Anyway, I didn't know that there was an alt.laser
so I'll xpost this to there.

How many instances of retinal damage has there been to spectators of laser
entertainment shows? I've never heard of one. Although not legal in the
US, in other countries, laser entertainment systems with output power of
over twenty watts are regularly used directly on audiences. The laser is
"scanned" using fast moving mirrors or put through various types of
diffraction optics. The levels are far lower at any given observer point.
But they're still often well over 5mW.

moo

[email protected]

February 1st 05, 12:35 AM

> "Pilots"? More than one?

The letter that one of the members on the laser forum, Skywise,
received from the APSA refers to multiple pilots with retinal burns.
Here's the link to his Web page:

http://www.skywise711.com/lasers/APSA.html

> "Anyway, I didn't know that there was an alt.laser"

Technically, it's alt.lasers .
> so I'll xpost this to there.

So I see.

Skywise

February 1st 05, 01:02 AM

wrote in news:1107218116.856975.93780
@c13g2000cwb.googlegroups.com:

>> "Pilots"? More than one?
>
> The letter that one of the members on the laser forum, Skywise,
> received from the APSA refers to multiple pilots with retinal burns.
> Here's the link to his Web page:
>
> http://www.skywise711.com/lasers/APSA.html
>
>> "Anyway, I didn't know that there was an alt.laser"
>
> Technically, it's alt.lasers .
>> so I'll xpost this to there.
>
> So I see.

Thanks for pointing these folks to the right place.

Also, the APSA is not a government organization.

My conversations with the president of the APSA have not
shed any light on the situation.

The claim of retinal damage is still anecdotal.

Laser induced retinal damage is also difficult to diagnose.
It takes an opthamologist with experince in laser injuries
to make a proper diagnosis. So far, all I have been told is
that the diagnosis was made by "a physician."

Also, the descriptions of the symptoms reported are
inconsistent with laser injury. The descriptions I have
heard are more consistent with temporary irritation of the
cornea or outer eye and eyelids due to excessive rubbing
or irritation due to dirt or dust.

My calculations show that in at least one incident where
the aircraft was at 8500 feet that it would take a very
powerful laser to cause eye damage at that distance. The
beam simply spreads out too much, even with collimating
optics.

If such powerful lasers were used, they would have been
easily seen by witnesses on the ground. When I asked about
such witnesses, none are known. So either the beam was not
so powerful or there just didn't happen to be anybody
looking at the time.

Then there is the difficulty in tracking the aircraft. In
one incident it is claimed the laser tracked the aircraft
for 15-20 seconds. I own a telescope and I have many times
tried manually tracking a plane to watch it through the
scope. It's difficult at best. The higher the aircraft is
the easier it is due to the slower apparent motion. But the
higher the plane is, the more powerful the laser needs to
be to cause retinal damage.

The only thing that is certain and is indisputible is that
even a small laser can potentially be a hazard to aircraft
operations at critical times such as final approach.

My efforts are currently concentrating on the alleged
retinal damage.

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy

Home of the Seismic FAQ
http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html

Sed quis custodiet ipsos Custodes?

AES

February 1st 05, 01:43 AM

In article >,
T o d d P a t t i s t > wrote:

> >And just for side interest, the LCD screen on my expensive 21" Sun
> >monitor is polarized exactly wrong, such that you simply can't use it
> >while wearing polarized sunglasses. The Sun engineers who designed it
> >knew computers, but not optics.
>
> Another aside - aviation instruments are often designed with
> circular polarizers so the brightness doesn't change at any
> angle when wearing polarized sunglasses.
>

Thanks -- interesting, and the sensible way to do it.

AES

February 1st 05, 03:27 AM

In article om>,
wrote:

> The letter that one of the members on the laser forum, Skywise,
> received from the APSA refers to multiple pilots with retinal burns.
> Here's the link to his Web page:
>
> http://www.skywise711.com/lasers/APSA.html
>

Just for the record, I'm thoroughly familiar with all the technical
evidence and much of the non-technical evidence in one of the cases
mentioned in passing on this web page, involving a U.S. Navy captain who
allegedly suffered eye damage as a result of being lased by a Russian
freighter in the Strait of Juan de Fuca some years ago while he was
photographing the Russian ship from a Canadian military helicopter that
was circling around it. I'm equally thoroughly convinced that he was
not lased by the freighter, in full agreement with the results of a
lengthy and detailed investigation of the incident carried out by the
U.S. Navy, and also the verdict of a civilian jury in a Seattle court in
which he subsequently sued the Russian freight line for the damages he
believes he suffered.

I have little or no knowledge concerning the possible use of
higher-power lasers to cause significant or permanent eye damage in
military conflicts (except to note that, in common with a number of
other potential weapons systems, the military might be inhibited in
fielding such weapons by practical considerations associated with things
like as serious risks of accidental "friendly fire" damage to own side
forces).

As I've noted in an earlier post, however, I've been told by what I
think are reliable sources that there have been at least some instances
of medium-power visible lasers being used for "dazzle" effects on
military pilots in conflict situations. I would also express a
technical opinion that even quite low-power visible lasers, including
red and especially green laser pointers, could produce significant and
potentially dangerous effects on pilots in some limited situations, at
distances which might be in the few thousand foot range.

[email protected]

February 1st 05, 04:24 AM

> I have little or no knowledge concerning the possible use of
> higher-power lasers to cause significant or permanent eye
> damage in military conflicts

In 1994, I was employed by a military sub-contractor as a Laser
Technician II. The clean room was divided in half. On one side was the
team that was building a YAG-based, non-eye-safe, laser range finder. I
was informed that it could only be used in areas where there weren't
likely to be people. The Geneva Convention prohibits the use of
non-eye-safe lasers on the battlefield, I was informed.

On the other side of the clean room, where I worked, was the team that
built the eye-safe, ErCr: Glass laser range finder. It could be used on
the battlefield with enemy forces present, because it was eye-safe. In
fact, the only reason for making that particular range finder was so
our military would not poke out the enemy's eyes with our lasers
whenever we took a distance reading (presumably before our side blew
the enemy's brains out with a canon).

Happy Dog

February 1st 05, 06:20 AM

> wrote in message news:
>
> The letter that one of the members on the laser forum, Skywise,
> received from the APSA refers to multiple pilots with retinal burns.
> Here's the link to his Web page:
>
> http://www.skywise711.com/lasers/APSA.html

Idiots. The APSA hype is a poorly written piece of fear-mongering. Even if
they got every other fact correct, until someone produces a pilot with a
real retina injury, they're not to be believed. They can't get medical
records. But such injuries would be aggravated assault or even attempted
murder. There would be an investigation that they could refer to. *That*
would have the real information on any such injuries.

moo

Happy Dog

February 1st 05, 06:24 AM

"Skywise" >

> Laser induced retinal damage is also difficult to diagnose.
> It takes an opthamologist with experince in laser injuries
> to make a proper diagnosis. So far, all I have been told is
> that the diagnosis was made by "a physician."

IIRC, it was recommended that laserists get retina scans before they begin
working with lasers. They're useful in determining if an injury has
occurred.
>
> The only thing that is certain and is indisputible is that
> even a small laser can potentially be a hazard to aircraft
> operations at critical times such as final approach.

Even that's debateable. (For laser pointers, anyway.)
>
> My efforts are currently concentrating on the alleged
> retinal damage.

Post your findings here.

moo

Jeff

February 1st 05, 10:46 AM

In article om>,
says...
> > I have little or no knowledge concerning the possible use of
> > higher-power lasers to cause significant or permanent eye
> > damage in military conflicts
>
> In 1994, I was employed by a military sub-contractor as a Laser
> Technician II. The clean room was divided in half. On one side was the
> team that was building a YAG-based, non-eye-safe, laser range finder. I
> was informed that it could only be used in areas where there weren't
> likely to be people. The Geneva Convention prohibits the use of
> non-eye-safe lasers on the battlefield, I was informed.
>
> On the other side of the clean room, where I worked, was the team that
> built the eye-safe, ErCr: Glass laser range finder. It could be used on
> the battlefield with enemy forces present, because it was eye-safe. In
> fact, the only reason for making that particular range finder was so
> our military would not poke out the enemy's eyes with our lasers
> whenever we took a distance reading (presumably before our side blew
> the enemy's brains out with a canon).
>

The convention mentioned (Protocol IV) does not prohibit non-eye-safe
lasers on the battlefield. It does prohibit the building of specific
use laser devices to intentionally blind people or use an existing
device to intentionally blind people. It does not cover the accidental
blinding of personnel as a result of the legitimate use of a laser
device (ie rangefinding or target designation). In any event there are
only 79 countries that have ratified the protocol (introduced in 1998)
and to date the US is not one of them.

Denny

February 1st 05, 02:58 PM

Hey Moo, did you ever do that promised laser test? I'm interested in
the results, if any...

As far as actually blinding a pilot (even if temporarily) at a
distance, it is a trivial task... It will take <roughly> $5K worth of
commercially available industrial equipment and one semester worth of
physics 101 ( a lifetime of brain washing in paranoid superstition and
fanaticism won't cut it)...

Denny

[email protected]

February 1st 05, 03:30 PM

Happy Dog wrote:
> Hello FBI surveillance software?
>
> Anyway, I am now in possession of one brand new "Jasper" DPSS 5mw
laser from
> bigha.com. That's the same laser used in the recent media hyped
incidents

Is your shift-lock perhaps stuck and you meant to experiment with 5MW?
[;)]

Allen

February 1st 05, 09:09 PM

"Denny" > wrote in message
oups.com...
> Hey Moo, did you ever do that promised laser test? I'm interested in
> the results, if any...
>

I think he is in the hospital having eye surgery :)

[email protected]

February 2nd 05, 01:27 AM

Hi, i'm new to Alt.lasers, so bear with me, i'm unfamiliar with the
setup of this forum, to be honest i find the google forums hard to
negotiate.I usually hang out at CPF, which was linked to here. Any
way, that getting OT.
What i wanted to bring up, was Skyline i read your email exchange with
the APSA, and was very impressed. Is there any way to include the
Amount of the "reflected" beam that would reflected off the cockpit
widows them selves? If not, Would you be able to include a refrence to
this?

Now i know that you guys have probably seen this:
http://www.lumalaser.com/redbaron.htm many times, but it relates to
this topic entirely. I don't know who's side of the debate it works
best for though

DaFiend

February 2nd 05, 02:21 AM

Hi, i'm new to Alt.lasers, so bear with me, i'm unfamiliar w=ADith the
setup of this forum, to be honest i find the google forums h=ADard to
negotiate.I usually hang out at CPF, which was linked to her=ADe. Any
way, that getting OT.
What i wanted to bring up, was Skyline i read your email exc=ADhange
with
the APSA, and was very impressed. Is there any way to includ=ADe the
Amount of the "reflected" beam that would reflected off the=AD cockpit
widows them selves? If not, Would you be able to include a r=ADefrence
to
this?

Now i know that you guys have probably seen this:
http://www.lumalaser.com/redbaron.htm many times, but it relates to
this topic entirely. I don't know who's side of the debate i=ADt works
best for though

Skywise

February 2nd 05, 03:52 AM

"DaFiend" > wrote in news:1107310913.876953.310020
@o13g2000cwo.googlegroups.com:

> Hi, i'm new to Alt.lasers, so bear with me, i'm unfamiliar w*ith the
> setup of this forum, to be honest i find the google forums h*ard to
> negotiate.I usually hang out at CPF, which was linked to her*e. Any
> way, that getting OT.
> What i wanted to bring up, was Skyline i read your email exc*hange
> with the APSA, and was very impressed. Is there any way to includ*e the
> Amount of the "reflected" beam that would reflected off the* cockpit
> widows them selves? If not, Would you be able to include a r*efrence
> to this?

BTW, it's "Skywise".

The genereal rule of thumb for the reflection off uncoated glass
at normal incidence (that is, not at an angle) is 4% per surface.
Not sure what it would be for the material actually used in
aircraft, but I doubt it's much different. It also will change
according to the angle of incidence, namely more reflection.
There could also be a small effect do to polarization. Different
polarizations reflect differently at shallow angles.

Before including such numbers in my calcs, I'd need real world
figures of reflection for the materials in use and their
dimensions and numebr of layers to be of much use.

But then, I'm not sure it would be worth the effort. Perhaps
other optics experts coudl comment?

> Now i know that you guys have probably seen this:
> http://www.lumalaser.com/redbaron.htm many times, but it relates to
> this topic entirely. I don't know who's side of the debate i*t works
> best for though

Oh yeah. We've been all over that. Do remember they were
dealing with a slow moving plane at very low altitude.

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy

Home of the Seismic FAQ
http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html

Sed quis custodiet ipsos Custodes?

DaFiend

February 2nd 05, 04:16 AM

my apologies, i was in a bit of a hurry.

Not a very good start.

Skywise

February 2nd 05, 05:35 AM

"DaFiend" > wrote in news:1107317792.491056.215260
@l41g2000cwc.googlegroups.com:

> my apologies, i was in a bit of a hurry.
>
> Not a very good start.

Don't worry about. No biggy. I hope I helped answer your
question, though.

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy

Home of the Seismic FAQ
http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html

Sed quis custodiet ipsos Custodes?

[email protected]

February 2nd 05, 10:30 PM

> The convention mentioned (Protocol IV)

I believe you mean, "alluded to," "inferred" or "referenced," because I
did not mention any convention beyond the Geneva Convention.

> does not prohibit non-eye-safe lasers on the battlefield.

I've heard that on this forum. I cannot state authoritatively the
reason that my employer told me something different than you are
telling me.

> It does prohibit the building of specific
> use laser devices to intentionally blind people or use an existing
> device to intentionally blind people. It does not cover the
accidental
> blinding of personnel as a result of the legitimate use of a laser
> device (ie rangefinding or target designation). In any event there
are
> only 79 countries that have ratified the protocol (introduced in
1998)
> and to date the US is not one of them.

Maybe so, but part of the military's decision not to use non-eye-safe
lasers in battlefield conditions probably involves protecting our own
soldiers. As I understand it, none of our own military personnel are
allowed outside or anywhere they might be exposed to the beam when
using the YAG laser range finder.

"AN/PVS-6, MINI EYESAFE LASER INFRARED"
http://www.globalsecurity.org/military/systems/ground/an-pvs-6.htm

BTW, as it happens, Sam's Laser FAQ includes a description of the unit
I was building. I don't recall ever seeing the final assembly, but I
sure recognize the oscillator sub-assembly.

"Photos of Varo Rangefinder Erbium Laser"
http://repairfaq.ece.drexel.edu/sam/laserpic/varopics.htm

Please refer to the following photo:

http://repairfaq.ece.drexel.edu/sam/laserpic/varo-lh.jpg

Notice the gold-colored section in the foreground with wires leading
out of both ends. My job was to assemble at least ten (10) of those
every day. I built them up on a base block, using a special jig that
appeared to be manufactured out of monel. It consists of two eliptical,
gold-plated reflectors; the Cr:Er:Glass rod (bottom of the elipse, and
about the dimensions of an ink pen refill cartridge); the flashlamp
(top of the elipse, about the size of a pencil); two metal support
arms; two sets of rubber grommets for sealing the rod and flashlamp
into the assembly via the metal support arms.

I had to inspect under a microscope each laser rod that I used. First,
I had to ensure that the ends of the rod had no more than an acceptable
number of inclusions (bright stars in the field of view of the
microscope) and scratches. Then, I had to use several types of solvents
and some lens tissue to clean the ends of the rod. I had to use the
microscope to ensure that my cleaning had been satisfactory. I placed
the rod in a V-shaped holder in the jig. The assembly would be built up
around it.

The grommets were tough to put on the laser rod. They were made of
rubber, which meant that they would contaminate the ends of the rod if
they touched each other. It is difficult to slip a grommet over a tiny
glass rod without allowing the grommet to touch the end of the rod. The
grommets, themselves, had to be cleaned prior to use, too, and might be
slippery from the solvents. I had to wear finger cots and use tweezers
to handle the laser rod and grommets, and I had to change out my finger
cots every 10 or 15 minutes to prevent my skin oils from contaminating
the laser rod.

Our materials suffered from various defects. The laser rods cost about
$800, and most were coated by a third party. My employer tried to coat
some of the rods, using our own optical shop up the hall. The results
were horrible. Under the microscope some of the rods had just a few
"stars." I understood those were coated by the third party. Other rods
looked like a sea of stars. I understood those were rejected rods that
our optical department had tried to salvage.

The flashlamps cost about $50. Our electronics shop brazed the
electrodes, but the results were often a brittle connection. If an
electrode broke off during assembly of the laser cavity, the cavity had
to be dis-assembled and rebuilt with a new flashlamp. This counted
against the 10 units that I had to assemble each day.

I found it expediant to bend the wires of the flashlamps "gently" when
I took them out of the supply bin, so I could eliminate the brittle
connections before I began assembly. My supervisor eventually noticed
that I was rejecting a lot of flashlamps, and told me not to test them
so aggressively. Of course, those wires could snap later during
testing, but that would not be my immediate problem. And, as long as
our units made it to out troops, breakage was not our problem at all.
However, very few of our units actually shipped. Most failed in
environmental testing.

After I finished building each laser cavity on its block, I placed the
unit on a cart. The next team took these units into a dark room, where
the optics were tested and aligned. Somewhere along that time, the
units were taken off the block I had used and were mounted on the plate
that you see in the photograph. I remember seeing the rotating mirror
(the Q-switch) and the circuit board, but that was a few yards farther
down the room from my workstation, so I did not see it very often. Most
of the time, I had my head stuck in the flowhood, "putting little
screws into little holes," as I like to put it.

Sam Goldwasser

February 3rd 05, 12:16 AM

That's a wonderful description of your assembly and QA procedures. :)

Could be immortalized in the Laser FAQ. :)

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.

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.

writes:

> BTW, as it happens, Sam's Laser FAQ includes a description of the unit
> I was building. I don't recall ever seeing the final assembly, but I
> sure recognize the oscillator sub-assembly.
>
> "Photos of Varo Rangefinder Erbium Laser"
> http://repairfaq.ece.drexel.edu/sam/laserpic/varopics.htm
>
> Please refer to the following photo:
>
> http://repairfaq.ece.drexel.edu/sam/laserpic/varo-lh.jpg
>
> Notice the gold-colored section in the foreground with wires leading
> out of both ends. My job was to assemble at least ten (10) of those
> every day. I built them up on a base block, using a special jig that
> appeared to be manufactured out of monel. It consists of two eliptical,
> gold-plated reflectors; the Cr:Er:Glass rod (bottom of the elipse, and
> about the dimensions of an ink pen refill cartridge); the flashlamp
> (top of the elipse, about the size of a pencil); two metal support
> arms; two sets of rubber grommets for sealing the rod and flashlamp
> into the assembly via the metal support arms.
>
> I had to inspect under a microscope each laser rod that I used. First,
> I had to ensure that the ends of the rod had no more than an acceptable
> number of inclusions (bright stars in the field of view of the
> microscope) and scratches. Then, I had to use several types of solvents
> and some lens tissue to clean the ends of the rod. I had to use the
> microscope to ensure that my cleaning had been satisfactory. I placed
> the rod in a V-shaped holder in the jig. The assembly would be built up
> around it.
>
> The grommets were tough to put on the laser rod. They were made of
> rubber, which meant that they would contaminate the ends of the rod if
> they touched each other. It is difficult to slip a grommet over a tiny
> glass rod without allowing the grommet to touch the end of the rod. The
> grommets, themselves, had to be cleaned prior to use, too, and might be
> slippery from the solvents. I had to wear finger cots and use tweezers
> to handle the laser rod and grommets, and I had to change out my finger
> cots every 10 or 15 minutes to prevent my skin oils from contaminating
> the laser rod.
>
> Our materials suffered from various defects. The laser rods cost about
> $800, and most were coated by a third party. My employer tried to coat
> some of the rods, using our own optical shop up the hall. The results
> were horrible. Under the microscope some of the rods had just a few
> "stars." I understood those were coated by the third party. Other rods
> looked like a sea of stars. I understood those were rejected rods that
> our optical department had tried to salvage.
>
> The flashlamps cost about $50. Our electronics shop brazed the
> electrodes, but the results were often a brittle connection. If an
> electrode broke off during assembly of the laser cavity, the cavity had
> to be dis-assembled and rebuilt with a new flashlamp. This counted
> against the 10 units that I had to assemble each day.
>
> I found it expediant to bend the wires of the flashlamps "gently" when
> I took them out of the supply bin, so I could eliminate the brittle
> connections before I began assembly. My supervisor eventually noticed
> that I was rejecting a lot of flashlamps, and told me not to test them
> so aggressively. Of course, those wires could snap later during
> testing, but that would not be my immediate problem. And, as long as
> our units made it to out troops, breakage was not our problem at all.
> However, very few of our units actually shipped. Most failed in
> environmental testing.
>
> After I finished building each laser cavity on its block, I placed the
> unit on a cart. The next team took these units into a dark room, where
> the optics were tested and aligned. Somewhere along that time, the
> units were taken off the block I had used and were mounted on the plate
> that you see in the photograph. I remember seeing the rotating mirror
> (the Q-switch) and the circuit board, but that was a few yards farther
> down the room from my workstation, so I did not see it very often. Most
> of the time, I had my head stuck in the flowhood, "putting little
> screws into little holes," as I like to put it.

[email protected]

February 3rd 05, 01:48 AM

" Spewed...and was shut down.

If your assembly skills are as good as your grammar skills, our poor
troops are screwed. Here's a hint, I won't even charge a fee for. But
yourself a Thesaurus.
BTW, I call B.S. on your story. I know our Government farms out to the
lowest bidder. But damn, your a full blown tard. Surely they would
not allow you to build field gear...surely...

[email protected]

February 3rd 05, 04:47 AM

> That's a wonderful description of your assembly and QA procedures. :)

Thanks, Sam. I'm sure this will find its way into my online diary, one
of these days (it's only been 10 years since I worked there!). There is
more I could add to it, but that's more along the lines of what life
was like at that time and place than technical description.

Erm... maybe I should add something about the QA Department? I don't
have a lot of technical details I could add, but the gossip would be
fine.

> Could be immortalized in the Laser FAQ. :

It gives me great satisfaction that I can Google my name in your FAQ.
Thank you for quoting me in the past, and I look forward to being of
service to you in the future.

Happy Dog

February 3rd 05, 10:24 AM

> wrote in message news:

> BTW, I call B.S. on your story. I know our Government farms out to the
> lowest bidder.

BWAHAHAHAHAHA!!!

moo

Allen

February 3rd 05, 02:32 PM

> wrote in message
ups.com...
> " Spewed...and was shut down.
>
>
>
> If your assembly skills are as good as your grammar skills, our poor
> troops are screwed. Here's a hint, I won't even charge a fee for. But
> yourself a Thesaurus.

But yourself a Thesaurus? But yourself a proofreader!

[email protected]

February 3rd 05, 06:37 PM

There is more I should say about the gold reflectors that make up the
walls of the oscillating cavity. I don't remember just now (though I
may have recorded it in my private diary) what the base metal is that
makes up the reflectors. The coating is gold.

The reflectors came to us the way all the other parts did, that is, in
a bucket that was placed on a shelf of left on a cart. The reflectors
were stacked on top of each other, with lens paper separating each
reflector half, and each half was identitical by design. Their smooth,
shiny, clean surfaces were beautiful. I had more of a chance to admire
their beauty as I had to clean each reflector with solvents prior to
assembly.

A third party originally gold-plated the reflectors, but my company
shifted to coating them in-house. I was impressed with the coating
quality, considering the trouble we had with the laser rods. But, I did
not have to examine the reflectos under a microscope for imperfections.
Even so, there were still issues with the coating.

There are tabs on the ends of the reflectors, which are supposed to fit
into slots set within the end pieces. Metal, mostly the gold-plating,
tended to build up on the tabs. Sometimes, the coatings were too thick
to allow the two halves to fit together inside the slot. In that case,
we had to file a little bit of the coating from the tabs. We had to be
careful not to file down to the deepest base level (I believe there
were three layers of metal making up the reflectors) or scratch the
inside surface of the reflectors. Fortunately, it was not difficult to
file down the reflectors according to specification, and I don't recall
any reflectors rejected due to filing.

I used a lens tissue to wipe up the filings from my workbench. I
thought the gold in them might eventually become a significant amount,
but it never did, as my supervisors had predicted.