Old 08-21-2012, 04:20 AM #1
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Question Effect idea with safety questions

I have this idea for a theatrical effect but I've become concerned about its safety the more I learn about lasers. I thought it would be a much better idea to discuss possible options on here before I try something stupid and blind myself.

The idea is pretty simple. There would be a high power laser on a moving head which would have two sets of diffraction grating wheels with several different shapes and patterns. The laser would ideally be a diode (for low maintenance) with enough power to be seen without any fog/haze and with a fair amount of ambient light.



Alright first question... I've taken apart a couple star field laser effects and they use a piece of stationary diffraction grating glass and an identical piece rotating directly infront of it to create a spinning, crossing array of beams. If you placed a diffraction grating of dots (lets say in a circle) infront/behind a piece that projected a star would you get a circle of stars or would you get a circle of pieces of a star?...

Secondly and most importantly... How can I shine just the laser beam, or the beam through one layer of diffraction, or through two layers of diffraction into an audience without causing damage?


I absolutely love the clean line lasers make but it's not worth anyones eyesight and a lawsuit. Would I be better off using a different light source with a collimated lens and a prism and sacrifice the thin, clean beam?

I want to avoid using any kind of lamp which leaves me with laser/LED diodes and I'm not sure I can get enough punch out of LEDs to get a similar effect...


Ideas?


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Old 08-21-2012, 09:27 PM #2
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Default Re: Effect idea with safety questions

Sorry I hope you dont mind me posting when I dont have the technical answers you are looking for, but suppose you were to ditch the lasers and go with another form of lighting try something called a flower strobe
some of those flower stobes can produce absolutely beautiful effects and if used within safety guidelines should be safe. they arent even heavy stobing effects like normal strobes I dont think so anyway just check out flower strobes and see what you think
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Old 08-22-2012, 04:36 AM #3
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Default Re: Effect idea with safety questions

They're great for house parties, school dances, and mobile DJs but they're very cheaply made and don't have much variety of effects they can create. I'm looking to create something of significantly higher quality. Something on par with the fixtures Martin, High End, Vari-Lite, and Clay Paky create.

I mean... You can't beat a laser


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Old 08-22-2012, 05:12 AM #4
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Default Re: Effect idea with safety questions

Firstly, a laser that'll have visible beams through a diffraction grating without fog is going to have to be many watts of power.

As for being safe, you'll have to do those calculations yourself. Divide the laser power by how many "beams" it produces and that'll give you a _very_ rough estimation of power per beam, I would aim to keep it under 10mW if it's going into the audience. Also remember that generally beams towards the centre of the grating will be the most powerful, so take your measurements there. Of course, if you live in the US, you're going to have to go through the whole variance process before you can actually use it in public.

I believe such fixtures already exist, too.

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