MPE calculations made easy

[kitatit]

Wow! Thanks Maurice. This is fantastic! You have done a great job of this.
I like it's layout. It is clear and logical. Much respect and thanks for making and sharing this valuable tool.

This would be great as an iOS or android app to have in your pocket.

I wonder if we have any developers on PL who can write apps?

Thanks
Kit

[allthatwhichis]

I want to see someway to attach a meter head to an iPod/iPad to make it a meter...

mccarrot, nice progy; would there be a way to get a value stating what the "safe" distance is given a certain power and divergence instead of entering the distance?

[taggalucci]

This would be great as an iOS or android app to have in your pocket.

I wonder if we have any developers on PL who can write apps?

I can. I'd just need to check the logic of the calculations and come up with a UI. Should be pretty straight forward, I would just need to find the time!

[mccarrot]

I'm happy to help you with fitting this is to a IOS app. We could even more simplify it for more easy use in the field.

[mccarrot]

mccarrot, nice progy; would there be a way to get a value stating what the "safe" distance is given a certain power and divergence instead of entering the distance?

Sure, but distance made more sense to me because any venue got a certain size you cannot control, but beam power and divergence (with my new lenses ) you can contol.

But if you come up with a good practical use why you would like this feature I will add it.

[White-Light]

This is not the simplified method, this is the real calculations method.
and 10x MPE is an option, if you enable it will give you a clear warning.
Have you tested the tool before giving this reaction?

Just for the benefit of anyone coming to this thread via google, shouldn't it pointed out that:

1. Each and every effect and beam effect in a display needs to be calculated individually using pulse and repetition rates for each and every beam effect displayed (which may mean hundreds of repeat calculations!)

2. The effect of MPE is cumulative so even if every effect scores within MPE doesn't mean the show is within MPE. The overall MPE needs to be calculated for the show as a whole

3. Breaks between exposure are usually necessary and breaks when beams are overhead or lasers are not in use need to be calculated and subtracted away from the cumulative figure at the point where they occur before cumulation restarts after the break

4. The above is extremely complex to calculate, especially cumulative MPE and shouldn't be attempted without proper training even using the calculator as the calculator just helps with individual beam effect calculations and not the show as a whole

5. If in doubt, use the tried and tested ILDA "simple" method (although even this isn't as simple as implied)

6. If in doubt at all about both methods, DON'T!! Keep beams overhead until you're properly trained and can calculate MPE safely and consistently correctly 100% of the time using one of the methods.

Please feel free to correct or add anything you feel is necessary Maurice.

[mccarrot]

Yes thank you.

This calculator is just to give you a rough estimation, to see if you are within the limits.

you cannot use this calculator to proof your show will be safe.

also the calculation is only correct for exposure times between 18µs and 10 s.

[-bart-]

Well, it would be nice if you could validate your calculations with your iphone camera with some applied optics, (nd filter,7mm aperture, lens).

It would also be nice if there would be an option in lasershow software, that would calculate the hottest spot of the hottest frame in a fixed (non live) show. That way you can modify the show and/or adjust overall brightness so the entire show complies with max mpe.

[White-Light]

It would also be nice if there would be an option in lasershow software, that would calculate the hottest spot of the hottest frame in a fixed (non live) show. That way you can modify the show and/or adjust overall brightness so the entire show complies with max mpe.

That's exactly what you can't do though with the non simple method because the effects are cumulative. So every single effect has to be individually scored then those effects cumulated together until a break point to ensure cumulative MPE isn't exceeded, then the break point removed from the total, then on resumption of audience scanning the effects cumulated once more on top of those that went before.

Hence why its so complex using the non simple method.

At least that is my understanding. I can't even confess to know how you cumulate effects as I doubt its as simple as adding them together!! I would guess its some kind of cumulative average but wouldn't know. I'm sure McCarrot could tell you how it works.

[kitatit]

Well, it would be nice if you could validate your calculations with your iphone camera with some applied optics, (nd filter,7mm aperture, lens).

It would also be nice if there would be an option in lasershow software, that would calculate the hottest spot of the hottest frame in a fixed (non live) show. That way you can modify the show and/or adjust overall brightness so the entire show complies with max mpe.

Hi Bart the software calculating hot spot feature is a great idea!

Being able to validate the results with the phones camera via nd filter and aperture sounds like it could be trouble.

Understandably people with a lot of experience with these matters are possibly concerned about this tool being seen by uneducated people as the last word on safety. Especially being in a consumer device like an iPhone or iPad.

Ideas like your software hotspot and an MPE app tool to assist in increasing show safety can help to bridge the gap for people who want to do things safely.

There is a bit of a no mans land between the "just don't do it" and the "just do it anyway" approach.


@ White-light. Thanks for the cautionary notes. I'm aware of some of these issues, and are slowly addressing them.

I'm in no rush to go cowboy doing shows.

I'm getting my ducks in a row in a considered way. Radiological council down our way is pretty strict. Not like the regs in the states though.

So far;
- I've Done my LSO training (It's not that comprehensive) it's mostly geared for medical fields here.
- Bought Marc's Fieldmax II and PM 10 (I've ordered a PM 3)
- Bought EyeMagic IRIS Colorsafe.
- Bought a scope

Things to do;
-Buy fast silicon photo diode
-Read a lot more
-Ask a lot more questions
-Practice practice practice.


Cheers
Kit