Hello and nice to meet you all

[klamerus]

I am looking for help with a project and am almost completely naïve (unless you count using a pointer). I would certainly appreciate any helpful response including redirection to a better source where this all may be found. I do have a science and math degree and some programming experience, but no laser work. I have been reading hours and not finding these answers.

I am looking to create a special effect for a decoration on our campsite at a music festival in Michigan in July. Theme is "out of this world". Non commercial, just amusement and to look cool

I am making a 8-10 foot scale starship enterprise which will fly (on a stand) about 4 feet above our 12 foot rv roof. It will be defending against a smaller ship, possibly themed on a toilet or something humorous. I want phasers to shoot out of enterprise at the space crapper. 2 beams red light, possibly a return fire from the toilet in green.

At a minimum, I want the lasers visible from the ground 50 feet away. Total travel to termination is about 15-20 feet. All above audience heads and all designed to terminate on each other.

My questions.
1. How much power for the red laser. I'm thinking 635nm for higher visibility. Mostly at night with some ambient light, I will make a little fog to try to show it better but any wind and that is moot. Will 100mW work? 500mW? 2W? I seriously have no idea. It sounds like a green laser could be 3-5 times less powerful and equally bright for any return fire
2. With any of the powers above, will I melt the receiving ship? Short 1 second pulses in sets of 2 pulses with 10 - 15 seconds between bursts. Can I damage my RV roof with that? Any special thoughts on absorbing surface? The ships will likely be urethaned and somewhat reflective.
3. Odd but I've never seen it asked, would rain present a vision hazard from incidental reflections or refractions?
4. Any specific recommendations on suppliers of laser diode modules that would likely serve this purpose would be appreciated. I can find them but have no knowledge to know good from bad and even if they are IR filtered.
5. Any ideas on a programmable timer switch that could repeatedly cycle through the laser bursts and possibly also flash and sound effects.
6. Finally, any suggested improvements or cool ways to make this concept better or safer. I am thinking 100mW and up, so IIIb or IV, so I want to take safety seriously for aircraft, passersby and myself.

Thank you for any suggestions and help, or any redirection to other forums to further pursue this.
klamerus

 

[Alaskan]

Welcome to the forum, some of your wants are opposed to themselves, the amount of power to make the beam impressively bright from that distance may well burn your model, but it depends upon what it is made from, that I don't know. Rain reflections? I haven't seen them so bright as to cause me concern, but I suppose it is possible, adding fog will allow you to reduce the power substantially and might also solve the concern regarding damage to your model, if made out of something which can melt.

Yes, green is a lot brighter to our eyes at a given power level than red, or blue for that matter which are on opposite ends of the spectrum sensitivity to our eyes. Timers are easy to find on ebay. I won't suggest power levels, but for public display, even if non commercial, technically, you will require a laser show permit.

 

[cyberdoc]

Welcome to LPF, klamerus. There are many nice people here who’ll be happy to listen to your questions and help when possible. Because there are marked differences across local, state and federal lines, you’ll need to consult with professionals who are familiar with the specific regulations in your area. Safety is always paramount, and should be your primary concern. There are paid consultants who specialize in public laser effects, and you will do well to work with one or more of them. I wish you lots of luck in your endeavors. Take Care and always be laser safe.

-cd

 

[lasersbee]

Welcome to the Forum...
You will definitely need a Fog machine...
You may also need some optics to enlarge
the beam profile to make it more realistic
looking.

Since you are not familiar with High Powered
Lasers and thir safety concerns I would suggest
reading up on them on the Forum...

The Search Bar at the bottom of the Forum
pages is your friend...

Enjoy the Forum and be Laser safe.

Jerry

 

[klamerus]

Thank you laserbee, cyberdoc and Alaskan.

I had spent quite some time looking through here and photonlexicon and ILDA without finding good answers. But looking more, I was better able to find stuff. Please correct me if I am wrong on this and please continue to provide any advice.

It looks like enough power to be visible, especially at the lower range red of 635nm which more closely approximate the Enterprise after refit, would probably melt my models (and possibly motorhome roof). At least 500mW and probably more in clean air. So that is out. So I need more fog. Maybe 3 or 4 fog machines so the wind dissipation is less an issue unless it is blowing hard. So you probably can't help me with power without knowing the amount of fog and ambient light. I may just have to buy a couple and see how they look. Any recommendations would be good as to a starting point. 100mW, 20mW or any chance at all a 5mW beam would be visible in fog.

I can base a green on the red that works, if I decide to use one. You have helpful links to compare visible strengths.

Whether the FDA has jurisdiction over a non commercial show seems to be a question with several answers. Probably another forum. But my non-lawyerly read is that FDA doesn't usually have jurisdiction over non-commercial activities unless they have an interstate or international hook. That is a state jurisdiction and I don't see any Michigan laws on this. The CFR wording certainly is that the FDA does apply IF the show is "public" (even if not commercial), but wording so doesn't automatically make it so. Especially in a CFR vs US Code. There are a lot of home holiday projectors which are sold and used and very public and unless they all are under 5 mW, then there is precedent for non-commercial-displaying lasers in your own space, even outside. I could argue that my own campsite, paid for by me, with no personal gain in the display, is similar to a home display. I suspect this is a can of worms and I don't mean to start an argument, but if there is clear case law on this anyone knows of, I would love a point to a reference. Clearly I am not willing to go to jail over this and if a peace officer asks me to shut down, I will.

I could avoid the whole issue by keeping under 5mW, or by getting a variance. I have time and the form looks simple enough as do the safety precautions that I SHOULD be using anyway if I am using a laser in public. The block, to me, seems to be that the individual lasers would need to have a variance to be used "for demonstration" from the manufacturer. Then I could apply for a variance to use them in my demonstration. All beams are terminated in my own space so FAA wouldn't play. Is that correct? Does Aixiz or any other reliable provider allow for purchasing a variance-issued, certified laser over 5mW?

I can look at enlarging the beam - with fog I agree it might look better. This is just for fun at a festival where many campsites will be heavily decorated. I am not really willing to spend money on a consultant. Especially when so many folks here and on other forums are able to provide so much good info and info. Great forum, by the way! If I can't make it safe, first, and legal, second, then I won't do it and my enterprise will have to be phaserless. But it looks like it should be doable safely and I have almost 4 months to learn and do it right. So please keep any thoughts coming.

klamerus

 

[GSS]

At the distance's of the props which i'm guessing over 10 to 15 feet, on top of possible movements plus the divergance of the beam I wouldn't worry to much about burning your props. You also mentioned short bursts. Maby just a bit of worry if your using a dark paper for the props.
Your RV should be fine..

 

[diachi]

Is this a public event? Where will it be held? Outdoors? Indoors?

 

[Encap]

Welcome and enjoy the forum.

See this especially excellent laser safety site: Laser Pointer Safety - A comprehensive resource, for safe and responsible laser use

It also has information on laws, rules, and regulations as well as variance and outdoor laser show information.

 

[klamerus]

Thank you for the link, ENCAP.

GSS - That makes me feel better. The props are painted (probably white) gloss on a polyurethane hard shell, probably thin like 5mm, over expanded polyurethane (Styrofoam) forms on a PVC skeleton. So it probably melts easily; and also, if I mount any laser inside a form, I will have some difficulty dissipating heat. I am a little worried about reflections off the finish and would like any suggestions on how to make the impact area less reflective, but unobtrusively so. For all these reasons, I would rather go lower on power and higher on fog. The laser is only one piece of a larger display, though admittedly the coolest and the one that is taking the most thought (and money)

diachi - it is a music festival. The display will be at our campsite, about 2 miles from the actual festival area. It is heavily attended and the particular campground our site is in is probably several hundred campers and perhaps 500 - 1000 people. Many will be decorating also with props, lights, and other cool stuff. But some of the campgrounds closer to the festival will be going all out with professional caliber displays and I am sure I will not have the only laser. Though I hope to have the coolest display in our campground. The festival is clearly commercial, but our displays are purely for fun and limited to on our own sites, which we have paid for. You can see the case I am making. If the festival were to do a display, even at our campground, it would be commercial, or if we were advertising for the festival or a product, but this is (to me) equivalent to a home display in a neighborhood of over-achievers - but with a home away from home. Still I would prefer to get a variance if I can, and that seems to require buying a laser already approved for display use. I could easily be wrong on all of this.

Also a note for anyone watching, I am a 50ish physician. This is a lark, but a lark I am willing to try to do right, and safety is paramount to me, too.