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ArcticMyst Security by Avery

Calling BS on this one.

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BoostJan,

I think the man received corneal and tissue abrasions from rubbing his eye. Considering the measured NOHD of a 1.1 watt Wicked Lasers blue pointer is ~600-800 feet, I have nothing more to work with as I do not know the exposure distance, exposure time, speed of the vessel, and true divergence in both axis of the "pointer".


Let me throw in a few more things here, based on hanging out around commercial shipping when I was a kid. Plus something often neglected in the simplified view of laser safety, which is "Optically Aided Viewing".

IF he was wearing eye glasses and thus had an effective 50 mm collection aperture, instead of a 7 mm pupil aperture, what he is saying may become somewhat plausible.

If he had binoculars in front of his eyes, the numbers get "believable".

But we can safely assume he irritated his eye rubbing it. It is a common, and I mean common, reaction to laser flashes. The media might have taken a common American Phrase "Rub Burn" and turned it into a "third degree burn".

Anyone who has played baseball or soccer knows sliding abrasions can hurt like hell.


This is the probably the situation as the Delta Airlines pilot, who claimed he had corneal damage from a non- Q-switched green laser.
If you read his statement, he rubbed his eye profusely after the beam hit him.

Which is more plausible, secondary injury or a thermal burn on a small spot of his face from a diverging blue LD? At close range, I'd admit he could easily have a thermal burn and eye damage, but at more then a few hundred feet, something else happened.

Without a doctor's statement, all I can do is speculate, in the hopes that a few LPFers learn about secondary injury and OAV.

After 20+ years in the business, I'll use one of my titles.. Which means I do have some formal education in this area. From what I am reading, I can speculate that you are hearing about an abrasion.

We don't have enough data to reconstruct anything, which is why I said "probably" in my first post.


Steve Roberts, Certified Laser Safety Officer...

This is exactly what happened. The absorption of the cornea and crystalline lens drops to next to none after ~440nm, so it's safe to rule out direct laser-induced damage to the front of the eye assuming the laser really was 450nm.

And third degree burns from a laser at long range? C'mon, use common sense. If the laser CoherentRays linked was actually the laser used, we can probably assume it's 1-2W maximum.

So aside from possible retinal damage, the laser didn't cause any harm. Any damage he received to the front of his eye or eyelid was, without a doubt in my mind, self-inflicted.

This is just another media attempt at vilifying lasers and making them sound like weapons of mass destruction, rather than the amazing technological achievement that they really are.
 





LSRFAQ

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Oxide Wrote:

"So aside from possible retinal damage, the laser didn't cause any harm. Any damage he received to the front of his eye or eyelid was, without a doubt in my mind, self-inflicted."

I have to disagree here. But only with the semantics..

Some place at home I have the equations stored to calculate the energy delivered from Aided Viewing. It would be significant in this case, If he had the right pair of glasses with a converging lens.

Its not "self inflicted" when an outside, unexpected, event like this causes a nearly involuntary reaction. He did what his brain would have done anyways, which was to try to move the "sharp object" before further damage was done. I just wish there was a better term for what probably happened in less then a second.

From the legal and medical points of view, the laser hit initiated the damage. His response was exactly as expected.


Steve
 
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I have to disagree here. But only with the semantics..

Some place at home I have the equations stored to calculate the energy delivered from Aided Viewing. It would be significant in this case, If he had the right pair of glasses with a converging lens.

Its not "self inflicted" when an outside, unexpected, event like this causes a nearly involuntary reaction. He did what his brain would have done anyways, which was to try to move the "sharp object" before further damage was done.

From the legal and medical points of view, the laser hit initiated the damage. His response was exactly as expected.


Steve

That's pretty much what I meant. I should have worded it differently.

Of course he's going to react when a laser hits his eye, and I'm not saying that it's not the culprit's fault. But when I said "self inflicted" I just meant that it wasn't directly inflicted by the laser, and was an indirect result of the laser strike.

The laser is the root of the other problems, but it didn't directly cause them, his hand did. If he had been prepared for it, he might have reacted differently.

Also, I'd love to have a look at those equations if you find them! :beer:
 
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LSRFAQ

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That's pretty much what I meant. I should have worded it differently.

Of course he's going to react when a laser hits his eye, and I'm not saying that it's not the culprit's fault. But when I said "self inflicted" I just meant that it wasn't directly inflicted by the laser, and was an indirect result of the laser strike.

The laser is the root of the other problems, but it didn't directly cause them, his hand did. If he had been prepared for it, he might have reacted differently.

Also, I'd love to have a look at those equations if you find them! :beer:

I've been holding off on posting some of them because they tend to enable folks to write untested software for audience scanning. Last time I posted them a flawed app appeared. However I think I will do some redacting of the motion component and post them. Its an ancient government document on how to do safe exposure of audiences with laser show gear. One I'm sure BRH/CHRD somehow regrets publishing decades ago.

Steve
 
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Benm

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Not so HA-HA, Probably not so much BS in this case... The media is wrong, but they have it half-assed correct.

Quote ""burns on the outer coating of the eye and broken blood vessels.""

Its probably a "Secondary Injury", something that you only find mentioned in a few really good laser safety textbooks.

Classic definition of secondary injury: Your climbing a ladder and get flashed by the laser, your startled, and fall off the ladder.

This might be a media mix up there, but there are fairly standardized limits for first, second and third degree BURNS. This has nothing to do with the chain of causality, but only with how bad the burns actually are and what their permanent effects are.

Obviously getting startled by a laser beam could cause you to fall off a ladder into a pool of lava resulting in 3rd degree burns, but in such a case it would not be fair that the laser caused 3rd degree burns. Shouting in the same circumstance could result in exactly the same thing, but noone would seriously consider that shouting -causes- 3rd degree burns.
 
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This might be a media mix up there, but there are fairly standardized limits for first, second and third degree BURNS. This has nothing to do with the chain of causality, but only with how bad the burns actually are and what their permanent effects are.

Obviously getting startled by a laser beam could cause you to fall off a ladder into a pool of lava resulting in 3rd degree burns, but in such a case it would not be fair that the laser caused 3rd degree burns. Shouting in the same circumstance could result in exactly the same thing, but noone would seriously consider that shouting -causes- 3rd degree burns.

NEVER work over a Pool of Lava with Lasers in use nearby !

NEVER use your Laser NEAR a person
who is working on a Ladder above a Lava Pool !
 
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please read the stickies RobertKoa This is the second time your Necro Posting! in some threads its ok but 99 percent of them it is not. Before you post any thing Else go threw all the Forum stickies on how to behave here on the forum.
 

Razako

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1071558-1068655_necro_super.jpg
 
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This all supposedly happened right where I live. I hadn't heard about it locally, but will look for it now that I am aware. I agree that it is not possible to get the burns they are talking about at the distances claimed and at the divergence of the laser. Puget Sound is pretty choppy water most of the time. I can't see any more than a fleeting exposure. Local news everywhere is always sensationalized.
 
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I'm suprised no one questioned how a single person was able to hit two different people on opposite sides of a 350 foot boat in seperate wheelhouses. what, did the boat the "laser attacker" was on cirlce the ferry enabling him to hit them both or did the ferry turn around after the first hit and then get hit again?
 
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