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From: DougD on 18 Jul 2008 16:26
In article <C4A4D453.5CA5C%kotroczo(a)mac.com>, Joe Kotroczo <kotroczo(a)mac.com> wrote:
>On 17/07/08 0:16, in article 66da4$487e6d7a$471fb991$30435(a)ALLTEL.NET,
>"George's ProSound Company" <bmoas(a)yahoo.com> wrote:
>
>> its not sound , the light show at a rave has blinded several attendees
>> instead of lights/blind this report could have been sound/daf
>> be a responsible provider and protect your audience, even when they, or the
>> promoters don't know any better
>
>The difference is that unlike lights or sound you can't turn down lasers.
>They always run at full power. So given the change in conditions (tents
>being set up) the right decision would have been to kill the lasers.

I'm not here to start anything, but that statement about not being able to
"turn down" a laser is just not true. Almost all lasers have at least a basic
current control, and in the case of display lasers, most are modulated
through AO devices which can control power from 0-100%. And even
in the most basic schemes, there are mechanical shutters which can
be used to attenuate the output. So, even if they were using a 40 watt
freq. doubled YAG which is popular these days, you can still limit
the output to about 1 watt which is fairly typical for a indoor venue.

d.
From: Eeyore on 18 Jul 2008 16:39


DougD wrote:

> Joe Kotroczo <kotroczo(a)mac.com> wrote:
> >On 17/07/08 0:16, in article 66da4$487e6d7a$471fb991$30435(a)ALLTEL.NET,
> >"George's ProSound Company" <bmoas(a)yahoo.com> wrote:
> >
> >> its not sound , the light show at a rave has blinded several attendees
> >> instead of lights/blind this report could have been sound/daf
> >> be a responsible provider and protect your audience, even when they, or the
> >> promoters don't know any better
> >
> >The difference is that unlike lights or sound you can't turn down lasers.
> >They always run at full power. So given the change in conditions (tents
> >being set up) the right decision would have been to kill the lasers.
>
> I'm not here to start anything, but that statement about not being able to
> "turn down" a laser is just not true. Almost all lasers have at least a basic
> current control, and in the case of display lasers, most are modulated
> through AO devices which can control power from 0-100%. And even
> in the most basic schemes, there are mechanical shutters which can
> be used to attenuate the output. So, even if they were using a 40 watt
> freq. doubled YAG which is popular these days, you can still limit
> the output to about 1 watt which is fairly typical for a indoor venue.

I would agree with you. Mind you, the Russians were also responsible for Chernobyl so
maybe they forget a power control ?

Graham

From: DougD on 19 Jul 2008 00:30
In article <4880FF98.FC8A365F(a)hotmail.com>, Eeyore <rabbitsfriendsandrelations(a)hotmail.com> wrote:

>I would agree with you. Mind you, the Russians were also responsible for
> Chernobyl so
>maybe they forget a power control ?
>
>Graham
>

Well, I suspect that there just aren't the reg's that we have here in N.
America. Prior to 1976, there were no safey laws in the US and a
certain band with the init's BOC went and torched some fans eye's.
Since then the industry has been under the overly heavy hand of the
Fed's/CDRH, and also local radiation control offices. It's turned into
a nice $$ operation for the gov., and I think it's gotten way out of
hand. Europe has handled it a lot better for the most part, as well
as Asia. Somewhat ironically, after the millions spent by the laser
display industry in the US to comply with all the safety laws, it will
end up being some idiot with a $20 laser pointer that brings down
a helicopter that will be the first real physical damage ever done in the
US post the 76 laws taking effect. I think folks that work in sound and
lighting would be shocked at what has been done to the laser display
industry in the name of safety, and should serve as a warning if they
ever decide that maybe some folks have lost their hearing or have
had the exact same kinda of retinal burns from arc lamps.. Don't
think that it can't happen!! Not that I'm against safety, the common
sense type backed up with good science.

$.002

d.
From: Eeyore on 19 Jul 2008 04:14


DougD wrote:

> Eeyore wrote:
>
> >I would agree with you. Mind you, the Russians were also responsible for
> > Chernobyl so maybe they forget a power control ?
> >
> >Graham
>
> Well, I suspect that there just aren't the reg's that we have here in N.
> America.

I suspect you're damn right !

You know why Cherobyl was so especially bad ? There was NO containment building whatever ! Look up the
RBMK reactor design on wiki ! The latest European standardised reactor design (2 examples currently in
build) has something like EIGHT foot reinforced concrete walls for containment. TMI had 3 or 4 foot
walls and they did the job too.


> Prior to 1976, there were no safey laws in the US and a
> certain band with the init's BOC went and torched some fans eye's.
> Since then the industry has been under the overly heavy hand of the
> Fed's/CDRH, and also local radiation control offices. It's turned into
> a nice $$ operation for the gov., and I think it's gotten way out of
> hand. Europe has handled it a lot better for the most part, as well
> as Asia. Somewhat ironically, after the millions spent by the laser
> display industry in the US to comply with all the safety laws, it will
> end up being some idiot with a $20 laser pointer that brings down
> a helicopter that will be the first real physical damage ever done in the
> US post the 76 laws taking effect. I think folks that work in sound and
> lighting would be shocked at what has been done to the laser display
> industry in the name of safety, and should serve as a warning if they
> ever decide that maybe some folks have lost their hearing or have
> had the exact same kinda of retinal burns from arc lamps.. Don't
> think that it can't happen!! Not that I'm against safety, the common
> sense type backed up with good science.

And now you get kids deliberately blinding pilots on final approach with their effing toy lasers !

Jeez.

Graham

From: DougD on 19 Jul 2008 06:38
In article <4881A253.BF482584(a)hotmail.com>, Eeyore <rabbitsfriendsandrelations(a)hotmail.com> wrote:

>> Well, I suspect that there just aren't the reg's that we have here in N.
>> America.
>
>I suspect you're damn right !
>
>You know why Cherobyl was so especially bad ? There was NO containment building
> whatever ! Look up the
>RBMK reactor design on wiki ! The latest European standardised reactor design
> (2 examples currently in
>build) has something like EIGHT foot reinforced concrete walls for containment.
> TMI had 3 or 4 foot
>walls and they did the job too.

Yeah, I had a development contract to do a 3D visualization system for the
Temelin nuke that was to be built in the Czech Republic (it was still CZ at
the time) sitting on their border with Austria. Westinghouse had the
contract on the control portion, with the reactors coming from Russia.
The Austrian's were so freaked out about having this reactor on their
border that it just about went to war to get it stopped, and it eventually
was at about the 75% point. It was one contract I didn't mind getting
stiffed on as I really did like the idea of having to be working on site
when they first powered that thing up!!

>And now you get kids deliberately blinding pilots on final approach with their
> effing toy lasers !
>
>Jeez.
>
>Graham

Well, I've worked with touring lasers since about 85, and lab lasers for a few
years before that, and the consensus with my "brethren" in the biz is that
it's fairly improbable to really "blind" anyone in an aircraft in just about
any attitude from the ground using a handheld device. Maybe if you were
able to get within a few hundred feet at takeoff, or landing, but in both
cases the cockpit is in the wrong attitude to actually hit anyone. As is
typical with most folks that have worked in the biz, I've got 3-4 minor
retinal burns and one major, and I know guys that have a lot worse.
Because of the insurance, laser techs have to have retinal scans on
pre-hiring so you know how "damaged" the person is prior to putting
them out on the road, and these scan's get pretty ugly. In my case,
the worst one I got was from actually wearing safety goggles, and not
because they were needed, but because they were mandated by law,
so that's kinda why I got a bug about folks trying to enforce common
sense.. I suspect that if the lawyers in Russia don't get their hands
on the victim's of this accident, a fair amount of them should recover
to pretty much normal vision, or possibly requiring glasses in the
future. I doubt any were perm. blinded though as they human eye
is about the fastest shutter out there when it comes to averting from
bright light. And I'm hoping that this will bring in some regulation for
them, hopefully not as $$ or as complex as our's here in the US.

$.002
d
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