Audience Scanning??

[mliptack]

While researching the topic of audience scanning safety, we also looked into injuries from far more common things like telephones and sofas. You wouldn't believe how many THOUSANDS of emergency room visits are caused each year by fricken telephones...

I wish my girlfriend was a member here... She got up in her lofted bed to answer the phone frantically and hit her head on the spinning ceiling fan. Nice ER trip later... she's got a nice 1" missing patch of hair right above her forehead... the doctor felt bad cutting it.

And yes this topic is very interesting. Just thought I would add that comment in

[dsli_jon]

buffo, uv99, pangolin and DSLi-

the replies, evidence, educated responses and detailed knowledgeable arguments are ALL (in my opinion) valid to some extent.

i think the educational value and the safety value of this post speaks for itself especially when it is so well supported (to some extent) on BOTH sides of the debate.

i guess what im trying to say is sorry if i caused some sort of a members feud here. my intentions were NOT to try and discredit ANYONE or PROVE anyone wrong.

Hey Marc! -

... like the time-honored 'well-of-wisdom' that it is, says: ("The Hokey-Pokey") "...that's what it's all a-bout! *bling!*"

I think I can speak for the others in saying, no apology necessary - it's simply a process all 'newcomers' to the FORUM (though you might have 99 years in the laser biz, and are the direct blood-line decedent of 'Theodore H. Maiman, himself') have to go thru (I did) - you have to TEMPER your PASSION on a subject, and NOT GET PERSONAL - that is what gets the foreheads' a-roastin' - simply a matter of learning the 'Art of Diplomacy': how to say 'nice doggy...', until you can find a rock!

But you are right on the money when you say what I left up above - it is good for every one to see both sides, cause that's how un-voiced questions get answered, and everybody learns / grows...

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 - like hearing of people using themSELVES as 'MPE meters'

Mis dos centavos. ... peace..

- J

[Tribal Existance Prod.]

I will always be aware of laser projection safety in all situations. The employee's at the C.D.R.H. have told me many stories as some of them have become friends over the years," no kidding". I will never work on any systems while an event is projecting live, after my one time mistake with myself as I did have my laser safety glasses on my head but pulled them up to work on another powered down system for the Aerial and ground event in Chicago IL. U.S.A. never again. I'm also very happy to know how aware everyone is on this subject of eye damage as my left eye is now damaged with little vision. DSLI Jon has given me much hope on my future vision though..... I'm very happy with him for that. I myself want to thank everyone here for being a professional, as that in it self is very commendable. I will take everyone's upion and stated facts in consideration. I also want to thank many people/friends who I respect for their help in many situations and matters here on this wonderful PL site. Everything learned is always tought to all of my employee's. Keep up the great professional work in your industries, as we must all stick together to keep the bookings and sales long lasting for all to enjoy in a very safe manner with some of the large high power systems we all use for our work/ART aka Laser Light Shows.

Have the best year yet in 2008.
Happy Holidays

Marcus

[UV99LASER]

ARRGGG.. Matey
Beware the one eyed laser guy.
Skipp

[laseray]

I have been forwarded this very interesting thread from Skipp...

I was that VISX engineer (now AMO, a shell of it's former glory but I digress) in question that he has referred to. While I was doing R&D for VISX I established the basis for proprietary ablation algorythms used for PRK and LASIK. This work in part included determining damaging eyes with various wavelengths and fluences. I was mostly concerned with some common wavelengths: 1064, 808, 633, 532, 355, 266, 248, 193nm and involved a variety of laser sources including Nd:YAG lasers and Excimers sources. Yes, I had a eye jig system that I called the "cow-cam" - and every morning I used to get fresh eyes couriered to me from the valley in a small foam cooler. Mostly big brown bessie eyes and pig eyes. I would clamp them up, hook a syringe to keep up the IOP, then ablate the eyes and capture the data in real time. Once we had a temp receptionist who thought I was getting my meals delivered every morning - I assured her that it was for the lab. She did not believe me so I showed her the contents, a dozen eyes staring back at her!! She let out a scream that left my ears ringing for an hour after that.

As for audience scanning - I think that I would leave the room and save my eyes unless I KNEW absolutely that it was safe.... I am a skeptic at heart. I would have to push the numbers and trust the Laserist.

My work has covered a wide range of wavelengths but most of it was at 193nm due to my employer's interest. My findings were that UV damage is cumulative. My interest in other wavelengths were secondary to the removal of tissue.

I have been in the Photonics industry all of my career and I have no eye damage dispite my sig.

[Pangolin]

Hi Laseray,

Welcome to PL. For the record, may we know your real name?

The laser safety standards definitely include cumulative effect, which is definitely more pronounced with shorter wavelengths. Within the MPE, the cumulative effect is referred to as the "multiple-pulse reduction factor", and (for visible wavelengths) is computed by taking the number of pulses, raising it to the -1/4 power, then multiplying that by the single-pulse MPE.

Within the blue region, the laser safety standards also recognize something called the "blue light effect" and other photochemical effects (as opposed to thermal effects). Any audience-scanning injuries would definitely be of a "thermal" in nature, and not photochemical.

At 193nm (which you wrote was your primary wavelength of interest) the beam stops penetrating the cornia, so that would not really be cause a "retinal injury" but rather what the laser safety standards refer to as a "skin injury". Of course, if you are ablating the cornia, the whole point is to create a "skin injury"... In any event, your research, at least as it applies to 193nm, isn't really applicable to audience scanning per se...

I certainly don't mind a skeptic. Nevertheless, for the record, I don't get the impression that you would go as far as to say that any laser exposure causes eye damage (as was attributed to you by Skipp), would you? As a reminder, Skipp's quote, from earlier in this thread, appears below:

A good friend of mine worked for a company called VISIX. They invented LASIK. Anyways he was an optical engineer on the project. Part of his duties was to do ablation testing on fresh pigs eyes. He would take the eyes and put them in a eye jig. He would then proceede to expose them to different levels of laser radiation. After exposure he would dissect them and document the damage.
He clinically concluded that any laser light entering the eye does SOME permanent damage no matter what.

Best regards,

William Benner

[laseray]

Hello Bill! Happy New Year to you (and everyone else reading).

My name is Raymond Ong. We have met a couple of times over the years at various trade shows in passing but I would not expect you to remember me. I think the first time may have been at a LDI after I had gotten a historical choreoGRAPHICS system - which dates me a little bit as it was Mid 90's. I have one of the original wire wrap boards.

Yes, most of my medical laser work is at very short wavelengths and long wavelengths. The closest applicable work I have done was in regards to PDT for AMD (Macular degeneration) where you remove abnormal blood vessels as well as the diode lasers for diabetic retinopathy(photocoagulation). In any case, these wavelengths are not the same as commonly used with laser light shows (for good reason). I believe that Skipp has a healthy respect for the laser's ability to cause eye damage but may have overgeneralized my statement of "cumulative effects"

At the same time, I do recognize your commercial interests in this. I have not directly addressed audience scanning safety issues from the regulatory side, although I certainly have seen it done in many clubs and parties over the years. Again, I would have to push the numbers to make me a believer as well as compensate for "enlarged pupil effects" that Skipp refers to .

[laseray]

Hello Bill! Happy New Year to you (and everyone else reading).

My name is Raymond Ong. We have met a couple of times over the years at various trade shows in passing but I would not expect you to remember me. I think the first time may have been at a LDI after I had gotten a historical choreoGRAPHICS system - which dates me a little bit as it was Mid 90's. I have one of the original wire wrap boards.

Yes, most of my medical laser work is at very short wavelengths and long wavelengths. The closest applicable work I have done was in regards to PDT for AMD (Macular degeneration) where you remove abnormal blood vessels as well as the diode lasers for diabetic retinopathy(photocoagulation). In any case, these wavelengths are not the same as commonly used with laser light shows (for good reason). I believe that Skipp has a healthy respect for the laser's ability to cause eye damage but may have overgeneralized my statement of "cumulative effects"

At the same time, I do recognize your commercial interests in this. I have not directly addressed audience scanning safety issues from the regulatory side, although I certainly have seen it done in many clubs and parties over the years. Again, I would have to push the numbers to make me a believer as well as compensate for "enlarged pupil effects" that Skipp refers to .

[Pangolin]

Hi Raymond,

Yes, I do remember you and glad to be in contact again. When we met years ago, you were doing work with laser diodes as I recall. I guess that was before you got the job with VISX.

I don't mind anybody's "heathy respect for a laser's ability to cause eye damage". In fact, I wish more people had a healthy respect... But exaggeration is another story, especially when the exaggeration is to the point of equating any and all laser exposure to "blasting retinas".

In any event, you never did answer my direct question. Could you confirm or deny Skipp's attribution to you, that you "clinically concluded that any laser light that entering the eye does SOME permanent damage no matter what"?

Regarding "pushing the numbers" -- no problem. There is lots of great information in the ANSI Z136 and IEC 60825-1 standards, as well as two great great sources of information about this on our web site. One was written by me, but the other was written by a respected PhD who works for the National Radiological Protection Board in UK. You can find them here:
http://www.pangolin.com/resguide09a.htm
and here:
http://www.pangolin.com/resguide09b.htm

And if you are ever in Florida, I would be happy to show you the system, how it works, and how it keeps the audience safe. By the way, it is not only me who says these things, but also the system has been peer-reviewed by some of the most respected people in the field of laser safety, not to mention CDRH themselves which took 2 years to review it, before it was approved.

Regarding your comment about my "commercial interests", yes, it's true. But it's not only a commercial interest in audience scanning, but in the health of the laser industry as a whole. We did a study which basically shows in territories where audience scanning is commonplace, the use of laser shows is expanding, but in territories where audience scanning is restricted, (US, UK, Sweden and now Australia), the use of laser shows is shrinking.

Nevertheless, just because someone has a "commercial interest" doesn't mean that the claims are necessarily skewed one way or another. For example, we can say that all drug companies have a "commercial interest" in getting a drug on the market. Does this mean all drugs are hazzardous even though the drug companies say they aren't? Or -- perhaps closer to home -- just because VISX has a "commercial interest" in LASIK, does this mean that LASIK is necessarily bad even though VISX says it isn't?

Best regards,

William Benner

[laseray]

Hello Bill,
You are partially right - In fact I worked for VISX twice: the first time developing the original STAR surgical system, then 10 years later on the Wavescan system. And in-beween I worked on diodes.

As for: "Could you confirm or deny Skipp's attribution to you, that you "clinically concluded that any laser light that entering the eye does SOME permanent damage no matter what"? " I will address that - I believe that Skipp was a bit over zealous and overstated the facts. That would mean even viewing with (appropriate) laser safety goggles would likely cause eye damage as ~some~ coherent light always gets to your eyes. This statement could be true but only IF there is sufficient irradience - and likely sources he would be referring to would be visible wavelengths at class 4 levels for a professional type lasershow. So "no" - Skipp's a clever guy just a little ardent.

Thanks for the invite - I would love to check out the system - now if I could only figure out an excuse to get to Florida instead of another Korea trip...

"Commercial Interests" are not necessarily "bad" - we all have them (usually) in some way or another. We are in agreement there. While I am a strong believer in the efficacy of LASIK, I certainly would not recommend having the procedure done on a NIDEK laser system (and not just because it is not a VISX system) The way technology is implemented matters. Alcon's LADARVISION appeared to be as good as VISX's but they recalled their systems in Feb '07.

sorry about the double post guys...