Audience Scanning??

[gottaluvlasers]

tribal-

i may be wrong here but i dont think UV99 or dsl-jon were refering to you at all in that accusation!! in an earlier reply by DSL, he asked if the persons initials (who got sued for $750,000) were "P.R." he referefd that question to UV99. i dont believe you were the business end of that assualt at all.
just an FYI-

[UV99LASER]

The point I am making is that at some point the power of the laser entering the eye will be so little that it will not be able to do any damage. FACT

Don't get me wrong, I am not saying we should all go audience scanning with multi watt lasers, I am trying to get the point across that*some* scanning can be safe. Proof of this is the varience that Bill from Pango has acheived.

I am intrested in details of this PR chap that got sued for $750,000 for popping some persons eye ball. Please supply a link.

Jim

Audience scanning is like smoking crack.
Smoke it a few times in small quantities and you will NEVER notice the permanent brain damage that has occurred.
The high will be great and you will go on your merry way none the wiser.

Smoke it on a regular basis and, well, we all have known crack heads.

If your buddy got permission to jump off the Golden Gate bridge would you do it just because he has permission?

The varience that Bill from Pango has acheived proves nothing.
It only proves that he has convinced the U.S. government to allow him to do something unsafe. It is in no way "safe". It might be "safer" but you still put yourself and anybody else you might radiate at a highly calculated ocular risk.

The ONLY way to truly guarantee the safety of your audience is to not expose them.
ANY missed calculations or equipment failure and it is bye bye eyeball.
Do you really want to take the risk of permanently injuring or even blinding someone?

I DO HAVE LASER INDUCED EYE DAMAGE.
So I know what I am talking about. 99% of the people I know who have laser eye damage did it with 100mW to 200mW lasers.

Again laser eye damage is cumulative.
And here once again is the definition that best describes cumulative.

b: increasing in severity with repetition of the offense <cumulative penalty>

So yeah at SOME point the laser power will fall very low.
But it will still be coherent.
The coherency of the light is what causes the damage.

Normal light is randomly polarized and non coherent. Therefore when it enters the eye it in not all concentrated on a single portion of the retina but across the retina.
This is not the case with a polarized or un-polarized coherent laser beam.
With coherent light it all comes from the same point in space and it is all going to the same point in space.
If you eyeball is in the way it will concentrate all of the light down to a 50 micron(or smaller) spot on the back of your retina.
It is the same as frying ants with a magnifying glass.

Just my opinion and experience.
If Bill from Pango wants to run around blasting retinas more power to him.
At this point in time there is just not enough evidence that longterm exposure to low power laser radiation is eye safe. Period.

Skipp

[UV99LASER]

is this the same guy who used to have the kids come close to the stage and he would burn a hole in their shirt for them?

Sh*t I never heard that one. But it does sound true.
My very first high power laser experience was with this twacker named Holly Wood Dog.
He had a spectra physics 2010 ten watt argon laser at this show.
This was before I knew the dangers of laser radiation.

I found out how dangerous lasers were that day.
He thought it was funny to make smoke come off peoples hats.
I swear to god.
He did it to five or six people.
The CDRH finally caught up to him in 1996. At that show ehe was terminating his 18 watt laser beams into the moving mirrors on the Intellabeams(old school technobeams). The laser beams were all over the place including the audience obviously.
I heard his fine was like 15 or 20 grand.
No Shiza.
Skipp

[mliptack]

ClanD, who ever you are thinking about, if it is this PR guy or not, is a complete nut job. Please tell me he gave the kids goggles

Sh*t I never heard that one. But it does sound true.
My very first high power laser experience was with this twacker named Holly Wood Dog.
He had a spectra physics 2010 ten watt argon laser at this show.
This was before I knew the dangers of laser radiation.

I found out how dangerous lasers were that day.
He thought it was funny to make smoke come off peoples hats.
I swear to god.
He did it to five or six people.
The CDRH finally caught up to him in 1996. At that show ehe was terminating his 18 watt laser beams into the moving mirrors on the Intellabeams(old school technobeams). The laser beams were all over the place including the audience obviously.
I heard his fine was like 15 or 20 grand.
No Shiza.
Skipp

While I am sure the effect of having a 18w terminated on an intellibeam was pretty cool to be at a safe area. That would be pretty terrifying. That is one of the reasons why I'm glad there are laws.

[dsli_jon]

i may be wrong here but i dont think UV99 or dsl-jon were refering to you at all in that accusation!!

Hey Marc - No, you were right...
http://www.photonlexicon.com/forums/...6&postcount=42

But I PM-ed Marcus this explanation and my number and said call me up and we chatted and ended up having a good conversation about a lot of cool stuff (and his experiences with this PR-hack), so we're all good - but thanks for helping 'keep the peace'!

Looking forward to chattin with ya on yer variance ??s - I'll have some free time tomorrow pm.... - ciao

-J

[dsli_jon]

I am intrested in details of this PR chap that got sued for $750,000 for popping some persons eye ball. Please supply a link.

Hey Jim -

PM-me or UV99 for details - would not be cool to post his name in public, here, but I was not kidding when I said 'that guy has single-handedly done more damage to the laser-show industry than all other 'hacks / throat-cutters' combined'... and how he 'epoxied to a 2x4 on top of several milk-crates with duct-tape and a cereal bowl'? (well, maybe the cereal bowl was a stretch, but not by much!)

- I would NOT be at ALL surprized to find out HE was the one responsible for the moratorium-causing incidents on outdoor laser shows in Vegas in ~ Dec. '95... - Audience scanning??...he was more into Audience BURNING... like Skipp said - the guy is a real hack and a danger...

OK, I'll shut up, now!

- J

[buffo]

Skipp, I appreciate your input here on PhotonLexicon. It's nice to get the perspective from folks that are doing shows commercially, and I'm sure you've got lots of great information to share.

However, you might want to reconsider some of the things you've posted recently with regard to laser safety. While I'm sure you are quite familiar with both lasers and laser eye exposure, so are many others, and to discount the vast body of evidence on the subject because of your specific injury is wrong. (Scaremongering is never productive.)

I DO HAVE LASER INDUCED EYE DAMAGE.
So I know what I am talking about.

Well, you know what it's like to suffer a laser-induced injury - yes. That alone does not qualify you as an expert in the field of permissible exposure levels for laser radiation. (For that matter, just because I've researched the topic myself does not qualify me as an expert either, which is why I'll cite my sources when I discuss the matter.)

First, let me say that I'm truly sorry that you've suffered an injury. I know a few others that have suffered the same fate (some of whom are members here on PhotonLexicon), and I can sympathize. I also agree that laser safety is important. But I must draw the line when you start making claims that "any laser light entering the eye does SOME permanent damage no matter what." That claim *has* been debunked several times.

See: http://www.iovs.org/cgi/reprint/16/6/521.pdf
http://archopht.ama-assn.org/cgi/con...ll/118/12/1686
http://www.mayoclinic.org/news2005-rst/2800.html

In each case, test subjects were exposed to Class 3A radiation from a laser for time periods varying from 60 seconds to several minutes. Only the last study found significant retina damage, and then only when using a green laser and a continuous 60 second exposure.

In fact, Dr. Robertson's study is often quoted as proving the case that laser pointers can be dangerous, even though he admits that the human blink reflex will normally stop the exposure after a maximum of .2 seconds. (Which is two orders of magnitude shorter than the dose required to cause damage!)

ILDA has also weighed in on the issue: http://www.laserist.org/Laserist/Safety_3.html

Or for a more pragmatic discussion, this article from Scientific American may suffice.

Based on this body of evidence, your claims are difficult to justify.

Now, everyone agrees that at some point you *do* reach a threshold where the amount of energy that enters the eye can cause damage. (No one is saying that scanning the audience with a static 2 watt beam is safe!) There are a number of factors that affect the amount of energy that enters the eye. (power level, beam diameter, duration of exposure, size of the pupil, just to name a few) But these factors are well understood and can be accounted for.

For example, the federal guidelines for laser pointers are set at a conservative 10% of the threshold where a .2 second exposure to a fully dilated pupil from a 2 mm or smaller beam would cause damage to 50% of the subjects. (Again, a .2 second exposure is a *really* slow blink, and the fully-dilated pupil simply means that ALL the power enters the eye...)

So if you can reduce the amount of light entering the eye to below Class 3A limits (which is exactly what the audience scanning variance that Pangolin earned does for you), then you *can* scan the audience safely.

I understand that your friend did some research, and clearly it made an impression on you. Coupled with your own injury, it has no doubt increased your awareness of laser safety. Plus, I expect you've seen more than a few other laser show operators doing things that are downright dangerous. (This "PR" clown sounds like a good example of this...)

While all the above is extremely unfortunate, none of it backs up your claim that all laser energy is dangerous to the eye. With regard to your friend's study, you have not provided any data about exactly how much laser radiation was applied to the test subjects. I suspect that his dose levels were considerably higher than Class 3A limits.

And when there are several peer-reviewed publications that show that class 3A devices are eye-safe and do not cause damage, well, I have to believe them over your claims.

The varience that Bill from Pango has acheived proves nothing.
It only proves that he has convinced the U.S. government to allow him to do something unsafe. It is in no way "safe".

Really? Based on what? Your experience? Are you claiming that, because you've worked in the industry, spoken with one researcher that did a study (which you don't have full information on), and have suffered a laser-related eye injury, you are now more of an expert on eye safety than either Bill Benner or the US Government? If so, then those are some mighty lofty claims, especially since you don't seem to know much about the contents of the Pangolin Audience Scanning Variance...

If Bill from Pango wants to run around blasting retinas more power to him.

I think your statements above border on libel. Bill is not "blasting retinas", and to the best of my knowledge he never has. He has an approved variance sanctioned by the CDRH that *documents* the exposure levels that will be experienced by the crowd when using their technology. It also includes contingency hardware that keeps the show safe in the event of numerous failures. That variance was nearly 2 years in the making.

Do you have any idea as to the amount of work that went into the calculations for that variance? Or any of the custom, projector-specific hardware that has to be installed? Or the pedigrees of the engineers and technicians that prepared that document? More to the point, have you even read the variance?

I suggest that before you start accusing someone as knowledgeable as Bill of being so reckless, you should at least investigate what that person has actually accomplished first.

I have discussed the topic of audience scanning with Bill a few times. I've seen the custom lens that is used on the aperture of the projector to widen the beam. I've seen the scan-safe hardware that goes into the projector, and discussed it's operation. And I'm far more willing to support both Bill and his team, plus the lawyers, technicians, engineers, and federal government employees that all got involved in making this happen over your unsupported claims. Bill Benner is *not* reckless (quite the opposite), and certainly isn't out "blasting retinas."

ANY missed calculations or equipment failure and it is bye bye eyeball.

Obviously you haven't researched Bill's variance. There are sections that cover both missed calculations (such as inserting a frame in the show that wasn't pre-calculated beforehand), changing scan rates, and equipment failure. They have planned for the unexpected, which is one of the main reasons behind the large lens on the aperture of the projector. (Not to mention some of the more nasty behavior of the scan-fail circuitry.) I won't go so far as to say that the technology is inherently safe, but it does have intrinsic safety features far beyond the scanner speed and frame calculations.

Do you really want to take the risk of permanently injuring or even blinding someone?

Do I? No, I don't. But I don't do commercial shows myself (though I have worked on a few shows with other companies). And if I did ever were to do a commercial show myself, I would not audience-scan. I'm not willing to take that risk. I don't have the knowledge, the equipment, the money, or the time to invest in the quest of obtaining a CDRH variance for audience scanning. That doesn't mean it's impossible, however. Just that it's something that is out of my reach as a hobbyist.

If your buddy got permission to jump off the Golden Gate bridge would you do it just because he has permission?

Of course not. But if my buddy had a US Government approved bungee cord system attached to him, and there was an open document explaining the safety margins of that cord, along with supporting information from the manufacturing company as to the structural soundness of both the bungee, the harness, and the anchoring mechanism, then yes, I would jump off the bridge, knowing that I'd be safe in doing so and that the experience would be one hell of a rush.

No one is trying to say that all audience scanning is safe. But to say that it's impossible to perform audience scanning safely is wrong.

Again laser eye damage is cumulative.

Assuming the exposure is above the damage threshold, I agree with you. But there is a safe exposure level, and you seem to be unable to acknowledge that fact.

The coherency of the light is what causes the damage.

This is also incorrect. The coherency makes lower power doses more damaging, because coherent light can be focused to a much tighter spot. But the coherency itself isn't the problem. It's the DOSE that's the problem. It just happens that the threshold is a *lot* lower for coherent light than it is for non-coherent light.

Normal light is randomly polarized and non coherent. Therefore when it enters the eye it in not all concentrated on a single portion of the retina but across the retina.

No, you are mistaken. The light that enters your eye is *NOT* spread across the retina. It's focused to a very small spot. (Usually near the fovea, where the highest concentration of photoreceptors are located.)

However, because of both imperfections in the lens and the fact that the light is incoherent, that spot is still fairly large compared to the (nearly) diffraction-limited spot that a laser beam can be focused to by the human eye. That diffraction-limited spot is what causes the power density to shoot through the roof, and *that* is where the danger lies. (And why it takes much less coherent energy to cause damage than it does non-coherent energy.)

But remember that the whole fovea is just 1 mm in size; it's a tiny fraction (less than 1%) of the total surface area of the retina. I don't consider 1% to be "across the retina" , do you?

At this point in time there is just not enough evidence that longterm exposure to low power laser radiation is eye safe. Period.

That's fine. Given that you've already suffered an injury, I understand why you feel that way. You only have one set of eyes, after all. But to accuse others of being reckless simply because they don't have the same injury-induced beliefs as you do, while discounting the science behind other people's efforts is just wrong. You're really not doing yourself or the industry any favors by making unsupported claims like this.

Yes, audience scanning can be dangerous. Yes, the work needed to do it safely is complex and arduous. Yes, it is *frequently* done incorrectly, and often with little (or no) regard for the audience's safety. Yes, it's not something that should be attempted by anyone other than a seasoned professional with the proper training and equipment to do it safely. BUT IT CAN BE DONE SAFELY.

Adam

[mliptack]

I think your statements above border on libel. Bill is not "blasting retinas", and to the best of my knowledge he never has. He has an approved variance sanctioned by the CDRH that *documents* the exposure levels that will be experienced by the crowd when using their technology. It also includes contingency hardware that keeps the show safe in the event of numerous failures. That variance was nearly 2 years in the making.

...to accuse others of being reckless simply because they don't have the same injury-induced beliefs as you do, while discounting the science behind other people's efforts is just wrong. You're really not doing yourself or the industry any favors by making unsupported claims like this.

Yes, audience scanning can be dangerous. Yes, the work needed to do it safely is complex and arduous. Yes, it is *frequently* done incorrectly, and often with little (or no) regard for the audience's safety. Yes, it's not something that should be attempted by anyone other than a seasoned professional with the proper training and equipment to do it safely. BUT IT CAN BE DONE SAFELY.

Adam

Well said Adam, I thought that the attack on Bill was a bit over the top. And I tried to say the same thing, but you organized and supported your claims

I think a good analogy of the threshold level is with another sense. Touch. If you have a pot on the stove and you just turned up the heat then you touch it, you can cold your hand there for a while, because the temperature is beneath the 'burn' threshold. Same with lasers, I am sure all of us have focused lasers and burned tape or something... but if your laser isn't powerful enough, it simply wont work. Our retinas are the black tape, of course much more sensitive and we have the added focusing lenses!

[UV99LASER]

Originally Posted by UV99LASER
The coherency of the light is what causes the damage.
This is also incorrect. The coherency makes lower power doses more damaging, because coherent light can be focused to a much tighter spot. But the coherency itself isn't the problem. It's the DOSE that's the problem. It just happens that the threshold is a *lot* lower for coherent light than it is for non-coherent light.

Your statement here proves my statement true. You can take a higher dose of non coherent light than you can coherent light.

Now before you get all hoity toity on me. Know that I have done thousands of shows. All my friends are optical engineers and medical laser guys.
I know a thing or two more than most about laser induced eye damage.

My first laser eye injury was caused by an audience scanning unsafe laser guy.
My eyes itched for 4 days accompanied by the worst 4 day pounding headache.
My second and most severe laser injury was self induced. The 20 watt laser I was working on was at waist level on a big cart.
It was at full power as I was cleaning and aligning it. Needless to say a shiny object intersected the beam path and shot the beam straight upward into my eye. It hurt BAD. The "tadpole" is not in my central field of view. It is in my upper peripheral field of vision. It kinda swims around up there. I still catch myself looking up to see what is up there.
Amazingly I still have 20/20 vision in that eye.

This brings me to This statement of yours.

"No, you are mistaken. The light that enters your eye is *NOT* spread across the retina. It's focused to a very small spot. (Usually near the fovea, where the highest concentration of photoreceptors are located."

This statement has a thread of truth. That thread is "light is focused to a very small spot". This is true it is focused into a very small spot on the portion of your retina that corresponds to the relative placement of the light source in space.

I will explain this in a simple way.
Light entering the bottom of your eye will be focused aprox 5&#176; above the fovea.
Light entering the top of your eye will be focused aprox 5&#176; below the fovea.
Light entering the center of your eye will be focused in the center portion of your retina the fovea.


The following quote was taken from the report you mentioned.
Laser Pointers and the Human Eye
This information is available here. http://archopht.ama-assn.org/cgi/con...ll/118/12/1686
Here is a little quote from that sight saying it took months to recover from a 5mW pointer injury.
Additional cases of presumed retinal damage were reported in a 19-year-old woman5 and in an 11-year-old girl6 following exposure to light from a laser pointer for approximately 10 seconds in the former case and following several multiple-second durations of exposure in the latter. In each case, subtle retinal pigment epithelial abnormalities were seen soon after the exposure, but the findings faded within months and the visual acuity recovered to 20/20 OU in each case. Two cases of apparent laser pointer–induced retinal injury were also reported by Almegbel and Yousef7 in 1999. Retinal pigment epithelial changes were seen in an eye of an 8-year-old boy and in that of a 15-year-old boy following exposure to laser pointers with power outputs of 5mW.

So your own info clearly shows the effects of 5mW pointers in the long run is benign. However it still takes several months to recover from the initial effects.

Here is a nice one.
You said.
"In fact, Dr. Robertson's study is often quoted as proving the case that laser pointers can be dangerous, even though he admits that the human blink reflex will normally stop the exposure after a maximum of .2 seconds. (Which is two orders of magnitude shorter than the dose required to cause damage!)"

I have seen more than a few people very high on drugs at almost ALL of the shows I have produced.
The drugs have obviously dialated their pupils to 8mm or so.
I ASSUME due to the dialation more light will enter the retina increasing the dose size.
I do not know if the blink rate is affected. But I have seen many people intentionally staring into lasers NOT blinking.

This I pulled from the ilda sight here http://www.laserist.org/Laserist/Safety_6.html

The Concept of MPE Levels
Since 1972, there has been an internationally agreed-upon hazard concept: the "MPE" or Maximum Permissible Exposure. Actually, the "MPE" includes many different exposure limits, depending on the laser wavelength and time of exposure. The MPE for a given wavelength and exposure duration means: 10 times less than the light level where 50&#37; of subjects' eyes had visible damage. Expressed another way: shining light at the MPE level into a subject's eye has a statistical chance of damaging 3 out of every 100 subjects. In summary, the MPE is a worst-case "safety factor". Exposure at the MPE level is already somewhat hazardous (statistically 3 out of 100 eyes would show signs of visible damage.) So additional factors such as a moving beam are assumed to further reduce the risk.


So according to this IF I did a audience scanning show at MPE for an audience of 10,000 THAN 300 of those people would show signs of visible damage.


This is still not "safe in my book". It is safer.


This quote I got from the article on pointers you mentioned.here is the web address.
http://www.sciam.com/article.cfm?id=can-a-pocket-laser-damage&page=2



"In FDA-regulated pointers, the laser power limit is set at one-tenth the actual threshold of damage. If a person sees a bright light, they will automatically blink, on the average in less than 0.2 seconds. This is referred to as the blink reflex, and it is considered when the limit is assigned for how much power will cause an eye injury. By the way, you shouldn't force a stare at a laser, just like you shouldn't stare at the sun or any bright light source."



This states that the safety limits are all based on the blink reflex of 0.2 second.




So IF you do not blink these limits will be exceeded.
It is of my opinion that audience members will not continually blink when scanned with a laser. I also think the tendency to resist blinking in order to observe the laser effects increases the higher the audience member is on illicit drugs.
I think audience members will stare at the laser effects in order to see them.
I also think IF they have an elevated pupil dialation of 2mm or more their radiation exposure will be double.

Quote:
Originally Posted by UV99LASER
The varience that Bill from Pango has acheived proves nothing.
It only proves that he has convinced the U.S. government to allow him to do something unsafe. It is in no way "safe".

Really? Based on what? Your experience? Are you claiming that, because you've worked in the industry, spoken with one researcher that did a study (which you don't have full information on), and have suffered a laser-related eye injury, you are now more of an expert on eye safety than either Bill Benner or the US Government? If so, then those are some mighty lofty claims, especially since you don't seem to know much about the contents of the Pangolin Audience Scanning Variance...

Right the FDA.
They approved ALL of the following drugs too.
These guys spent Billions on their PHD's who said their drugs were safe.
You should reshearch some of the FDA's failures here http://www.drugrecalls.com
Vioxx Recalled. On September 30, 2004
Rezulin recalled on March 21, 2000
Redux fen-phen recalled in 1997 when a report showed that as many as 30% of tested fen-phen users showed some heart valve damage. The U.S. Food & Drug Administration (FDA) has received reports of 123 deaths in which fen-phen was identified and continues to regularly receive reports of heart valve disease linked to fen-phen.
March 2005 FDA Orders Black Box Warnings On Antidepressants
The FDA ordered 14 antidepressant manufacturers to add "black box" labels warning that antidepressants can increase suicidal behavior in children.


This brings me to the next point.
I think if you are scanning the audience you are blasting retinas period.
If I am scanning a wall I am blasting said wall same difference.
I NEVER called Bill Benner "reckless".

I have seen very large projectiles flying through the air at several events.
I found a half full coke can in one of my projectors after a show one night. It came in through the rail port.
I assume a large projectile might dislodge or ever break Bill's lens from his projector.
How would that effect the exposure levels?

I am sure Bill did all of his home work.
IF everything works as calculated...
IF the electronics do not fail...
IF the diffusing lens stays in place....
IF the MPE levels are not met or exceeded....
IF the audiences pupils do not exceed 6mm dialation.
IF the show does not have to happen in the real world..
Then I would say audience scanning would be safe.

But those are a lot of ifs.
Fore sure you probably will not PERMANENTLY injure any one with a 5mW laser.
To say that audience scanning when done right is risk free is simply untrue.
A truer statement would be, Audience scanning when done right is "safer".

You said you would jump off the golden gate bridge and I quote
"But if my buddy had a US Government approved bungee cord system attached to him, and there was an open document explaining the safety margins of that cord, along with supporting information from the manufacturing company as to the structural soundness of both the bungee, the harness, and the anchoring mechanism, then yes, I would jump off the bridge, knowing that I'd be safe in doing so and that the experience would be one hell of a rush."

Hate to break it to you but....
However, even with the most stringent safety precautions, it is not possible to eliminate risks of injury, especially those which are actually associated with the sport of bungy jumping. One of the most significant risks particular to women is that of uterine prolapse. It is said that the speed and pressure of the bungy jumping can cause the to not only tip but, in some cases, slide out of its normal location and even out of the body itself. This, naturally, is very dangerous and potentially life-threatening.
Eye trauma is another very serious health risk from bungy jumping. One of the most dangerous types of eye trauma associated with this sport is retinal hemorrhage; this presents a very real possibility of losing one's eyesight. Bungy jumping also presents the possibility of orbital emphysema, which can also result in permanent loss of vision. On a slightly-lesser scale, but still noteworthy, are basic injuries to the eyes and their surrounding tissues.



Find this here http://infoboulevard.com/articles/he...gy-jumping.txt



I am sky diver we are regulated by the FAA. All of our equipment is FAA approved and regularly inspected and re certified. There are usually over 2 million sky dives in the U.S. in any given years. The death rate has been going down so it is getting safer. But it is still not safe.


Stats are here http://www.uspa.org/about/page2/relative_safety.htm



What I am saying is even if it is "done right" in a safe(r) manor, there will be accidents.
There will be injuries.
Humans are prone to making mistakes.



What I am saying is...
Is it worth the risk?
Somebody will lose a eyeball.
I am not fearmongering I am looking at this with a little common sense.
If you do not need to risk injuring a stranger than why risk it?
Skipp

[dsli_jon]

Hey Gents - (PS - isn't this a great forum?!

Before you guys come to 'fisticuffs' over the minutia of what I see as a lot of 'irrelevant-to-the-point-of-this-thread' data (ie- why are we discussing 1mW or 5mW anything in the context of real-world laser shows??), here is sort of a 'middle-ground' to consider: (some excellent 'food for thought' on both-sides in this and the next Subtitle...)

http://en.wikipedia.org/wiki/Audienc...injury_reports

I think the focus (excuse the word choice) has to be not the 'math', but what we see in the 'real-world' - since 100% accurate scanned MPE-measurement thru ALL types of 'typical show' fx IS very difficult, and there are SO many 'wild-card' factors LIKE: IF they blink, IF their pupils are not 'chemically dialated', IF none of the 'failsafes' fail - not to mention the factor of WAVELENGTHS-USED - 532 is potentially more damaging / mW to a fovea than, say, 650, (ie- green is absorbed by its' 'opposite' 'pink' better, and, therefore, ablates tissue faster than red or blue - why KTPs are used for surgery and not 20W red diode-bars) correct?

I do see valid points on both sides of 'The Force', here but, I personally have to agree a bit more with Skipps' whole 'slant' - here are, I think, (like anybody asked!) the most relevant points to this thread:

"You Guys who have scanned yourself with your 2 watt lasers should have your retinas photographed.

The reality is that if you(the average audience member) sees only one or two audience scanning shows in your life you will never notice your injuries.

(though it pro'lly WOULD be more balanced to say: ...'you may never GET injured, or, like some first-time ecstasy or crack-users, you may 'roll snake-eyes' and end up affected for life, even if you don't at first notice it')

However if you are a disco-biscuit munching up all night every weekend clubber... you might be in for a world of hurt."

Bottom line, as I see it: UNLESS a Sho Co HAS the proper equipment/know-how to perform safely, UNDERSTANDING of all apsects of the REAL dangers of A.S., - and permission - a Variance for it, it should continue to be a very strictly-controlled facet of laser shows, and even then, used SPARINGLY - just for a few, well-placed 'woah, that was cool' points in a performance...NOT every stingle stinkin' frame... I, for one, don't LIKE those kinds of shows, and I am sure I am not alone...

A truer statement would be, Audience scanning when done right is "safer".

And I submit that this little bit of real-world wisdom, for those, here, and elsewhere, who are just STARTING OUT (and asking very important-to-know-BEFORE-doing laser-shows - even turning it ON - questions like 'is it OK if I scan my eyes w/ my 2W?') is really the point.

I again submit that all the 'studies' at least show it would do EVERYONE good to have a more SERIOUS vs a more CAVALIER attitude towards the subject / practices - when I hear of people using themSELVES as 'MPE meters' ("for every show we set up, we "sample" the show from all points of audience access. If its uncomfortably bright at the closest points, we take measures to correct the issue.") NOT a criticism, but ! How long are you gonna be able to do that before you can't read too well anymore, dude?! And isn't the 'judgement' of what is 'safe' for others, really being reduced in 'accuracy' by every 'sample' likely damaging the very 'meter' (eyes) you use to judge by?

I will post my 'solution-opinion' again, and then go away:

I think every SALE of a laser system, SHOULD be regulated to include PROOF that the buyer has, at a minimum, completed a laser safety training class (in depth), and understands the power of the 'gun' he/she is buying - we have to get a license to drive a car (and yes, I know, cars take lives, lasers usually do NOT), but it is more an issue of encouraging self-regulation thru accountability - if you KNEW you could get your precious, money-earning laser-license - and maybe your LASER - yanked for not operating safely - INCLUDING AUDIENCE SCANNING - would that NOT encourage better responsability?

Though I still would not bet on PR.

- J