9W RGB special red beam!

[norty303]

As lasers get cheaper, people will put more and more higher powered lasers into smaller spaces. I was writing up my safety record for a spring festival last night and surprised and perturbed to find I was going to have to turn my 800mW greens down to under 100 to hit MPE. Although I would love to justify buying more and bigger lasers, I've realised that my 1-4W range of projectors will cover 95% of the jobs I do.

[greenalien]

Nice to see someone else using Phoenix 4! I agree about the excess brightness though, I'd like to see a copy of the MPE calcs for the show in the video...

[White-Light]

As lasers get cheaper, people will put more and more higher powered lasers into smaller spaces. I was writing up my safety record for a spring festival last night and surprised and perturbed to find I was going to have to turn my 800mW greens down to under 100 to hit MPE. Although I would love to justify buying more and bigger lasers, I've realised that my 1-4W range of projectors will cover 95% of the jobs I do.

I guess lenses are maybe the way to consider going as well Norty. Just depends on how well your projector modulates.

[dsli_jon]

*chrrreet* *chrrreet* *chrrreet* *chrrreet*

^ ..those are crickets...

[White-Light]

*chrrreet* *chrrreet* *chrrreet* *chrrreet*

^ ..those are crickets...

I know it sounds a bit obvious.....This is the trouble with not being able to say everything that you really want to say publicly.

I had a conversation with a leading laser safety expert the other day. Now as another expert recently pointed out in a thread on here, the problem with lenses is that when you increase beam diameter you change other factors as well that then serve to cancel out some of the advantages. We all know that and that's the line of calculation that has to be taken. That doesn't mean lenses can't be used, just that there are limiting factors to the gains.

Now the controversial conversation I had with another safety expert was that this person along with 2 of the biggest names in laser safety had conducted tests which all led to the same conclusion, namely that certain measurements currently believed to be necessary to calculate MPE can be thrown away entirely in the ordinary circumstance. The effect on this on lensing is that the limiting factors to the gains to be made (other than the visual limits of expansion caused when the beam appears too fuzzy) no longer exist. So lensing using this method of MPE assessment, potentially has a much bigger impact on what can be achieved power wise.

Unfortunately this is not an accepted standard and so can't be used as a means of accessing MPE for shows as it could possibly put operators in breach of local laws / leave operators open to legal claims in the event that damage was claimed.

Hence the reason why I've been vague here as I didn't want anyone coming to this thread and taking my report of this conversation as a green light to assess safety in this way.

However, if it ever did become the accepted standard for the simple method, the impact could be great from a lensing perspective.

[norty303]

^^ Was it really worth writing all that if you're not going to say what the details of the conversation were?

I thought that this place was all about having discussion and exploration of important topics, whether they are law/statute/guidelines/whatever...

[dsli_jon]

..and I was only 'chirping' at the lack of any response to Post 51.. ..All good-points, tho, Gents (relative to scanning people in the face w/ (supposedly.. ) 9W at close range.. that's an argument for another day.. Right now, I'd just like the answers to my questions...

ciao
j

[norty303]

FWIW, I think the lasers in the video indoors are 'only' ~2W, rather than the 9W one. Still, looks pretty bright from where I'm standing (sitting)

But let's not derail the thread further

[White-Light]

^^ Was it really worth writing all that if you're not going to say what the details of the conversation were?

I thought that this place was all about having discussion and exploration of important topics, whether they are law/statute/guidelines/whatever...

I thought I was being responsible but ok.

From my understanding and without naming the parties involved, the basic hypothesis is that you can forget about exposure duration / scan repeats etc. and all the other complex factors you might have to take into account even with the simple method. If you take a simple power meter reading from a static beam and at the closest audience point and its below 10mw on a 1cm 2 sensor or 5mw on a 7mm aperture then the show is safe provided it conforms to the normal parameters of what would be expected in a show ie no extreme effects.

This basically throws out of the window the whole concept of the necessity to take scan speed measurements using a fast photodiode to check the scanner velocity and calculate the dwell time etc based on the beam diameter etc.

A simple one off power meter reading with a sensor size at 1cm2 is all that's required IF this is correct. It's kind of a simple, simple method.

However, note that as I said above, no regulatory body to my knowledge has formally accepted this as the standard so anyone using it for commercial shows could face prosecution and in the event of any damage might find it very difficult to defend a civil suit.

I believe even with the simple method you are required to check scan speed although I'm sure that those of you who have done safety courses can verify more accurately what the current requirements are.

[greenalien]

@Whitelight - what you are saying is something that should definitely be discussed in more detail, but perhaps a new thread in the 'Displays & Shows' section would be a better place?