Laser beams and mirror balls

[Jivemaster]

Old disco effect, basically a collandar with a small fillament lamp at the centre. Lots of beams from a cheap machine which replaces your mirror ball on the floor, costs almost nothing, and has NO laser just a small lamp 12v 100w or 24v 250w (eg Kodak Carousel lamp).

[ken cattell]

mmm, old collender with a bulb underneath. nice simple and effective. Hang on; would that be a metal collender? better make sure its earthed in case it gets moved and breaks the bulb becoming live in the process. oh and use large thick cable you dont want it snapping when it moves. something about the size of transatlantic phone cable should do. No better still avoid metal collenders plastic would be better. err will it be able to cope with heat from the bulb not melting the plastic best put two wacking great fire extinquishers beside it just in case! or better still make it a large plastic collender so its ventilated. arghhh its enough to drive you nuts! good luck. :)

[dmxtothemax]

The best light to use on a mirror ball,

is the par 36 pin spot,

because it produces a small tight beam,

hense the name pin spot,

it will hit many mirrors at once,

this will give the effect you are looking for.

have a look here - http://www.theelectronicsshop.co.uk/par36cans.htm

 

I will be lighting beauty and the beast next year and would like to create an effect similar to the film transformation scene where shafts of light hit the ground. Although this is not possible in real life (easily)

 

I would like to know whether pointing a laser would create the effect of multiple laser beams emanating out from a central point or would it not do this.

 

ie. A half mirror ball rotating on the deck behind the beast with a laser rigged above.

 

Any ideas or variations welcome.

 

Thanks guys and gals

 

James

[norty303]

One way of getting around the 'chaotic' nature of a mirror ball would be to use a burst diffraction mirror.

 

This has a number of benefits:

1. The area that the beams hit can be carefully controlled

2. The power level can be controlled and measured by adjusting the power of the single beam fired at the mirror.

3. The (any) beams spilling into any audience area should be the lower order beams, meaning they'll naturally be lower power than the beams going into the 'airspace'

 

I believe that the blanket '<5mW' rule is a US 'thing', in the UK it relies solely on the MPE at the point of hazard. I won't get into MPE here as there are too many lines of thought on it, further 'confused' by a paper fairly recently that suggests 10xMPE scanning is acceptable....

[LXbydesign]

I think my brains just fried reading this post.

 

I would just go for 4 x Source 4's with 5 degrees lens or (wider with an iris) and point them onto the mirror ball. you could do a ripple chase as well for some animation.

 

Saying that, im waiting for the delivery of Martins RGB Laser! :-P

[The Seedage]

One way of getting around the 'chaotic' nature of a mirror ball would be to use a burst diffraction mirror.

 

This has a number of benefits:

1. The area that the beams hit can be carefully controlled

2. The power level can be controlled and measured by adjusting the power of the single beam fired at the mirror.

3. The (any) beams spilling into any audience area should be the lower order beams, meaning they'll naturally be lower power than the beams going into the 'airspace'

 

I believe that the blanket '<5mW' rule is a US 'thing', in the UK it relies solely on the MPE at the point of hazard. I won't get into MPE here as there are too many lines of thought on it, further 'confused' by a paper fairly recently that suggests 10xMPE scanning is acceptable....

 

(response probably isnt in the line of the OP, so moderators kill this off if you need to!)

 

Not sure if I totally agree on this one....

 

Yes, you can control the area that the beams can hit by focussing the primary beam, and yes any diffracted secondaries are a lot lower power, but its still a single beam, and compared to a mirror ball (which would most likely be rotating, and diffracting into many more beams), the likelyhood is that there would be more of a possibility of a 1st reflection beam getting direct into the audience by a mis-aligned effect (would only take a knock of the diffraction grating to potentially move the primary reflector into the audience), where as with a mirror ball rotating, at least the beam is moving... Again, must stress I'd always scan a mirrorball with a small ellipse or circle to further reduce the PD of the beam before it even gets reflected.

 

Most of the cheaper lasers (which by the sound of the OP is the area of budget he'd be looking at) are not variable output at the diode, in fact most drivers are ramped up to get the maximum out of a diode rather than set to a sensible long life setting sympathetic to the diode, therefore. Unless you are getting into decent control/gas tubes, the kind of effects being discussed wont have the luxury of reduced output of the diode....

 

I'd love to see that article that suggests that something 10 times more dangerous that the maximum is acceptable and safe.. Thats like saying, you're gonna die if a truck hits you at 50mph, but try hitting me at 500mph and try and justify it!!!

 

Back to the OP - Pinspots and Mirror ball.. Add colour in to make more magic!!!

 

Just my two penneth.... Off to the garage now to burn spiders while I program halloween!!

 

 

 

A concurrent post has been automatically merged from this point on.

 

I think my brains just fried reading this post.

 

I would just go for 4 x Source 4's with 5 degrees lens or (wider with an iris) and point them onto the mirror ball. you could do a ripple chase as well for some animation.

 

Saying that, im waiting for the delivery of Martins RGB Laser! :-P

 

LX By Design - Let me know how you get on with the Martin product!!

[norty303]

I'd love to see that article that suggests that something 10 times more dangerous that the maximum is acceptable and safe.. Thats like saying, you're gonna die if a truck hits you at 50mph, but try hitting me at 500mph and try and justify it!!!

 

Fair enough, its freely available on the ILDA website...

http://www.laserist.org/files/audience-sca...view_latest.pdf

 

If you want to see the context, here's the link to the holding page

http://www.laserist.org/safety-info.htm

 

Interesting details around trying to simplify MPE measurements and calculations as well.

 

 

BTW, whats the price on the Martin projector now? iirc, Kvant and RGB laser systems (and others!) do an equivalent model for a fraction of the £40k Martin were after....

[norty303]

http://www.laserist.org/files/audience-sca...view_latest.pdf

 

Its written by the Chair of the ILDA Safety Committee and the Executive Director of ILDA

[tomrbland]

Thank you for pointing towards that document Adam. It really puts it all in to perspective nicely. It was really quite an interesting read.

[The Seedage]

I'd love to see that article that suggests that something 10 times more dangerous that the maximum is acceptable and safe.. Thats like saying, you're gonna die if a truck hits you at 50mph, but try hitting me at 500mph and try and justify it!!!

 

Fair enough, its freely available on the ILDA website...

http://www.laserist.org/files/audience-sca...view_latest.pdf

 

If you want to see the context, here's the link to the holding page

http://www.laserist.org/safety-info.htm

 

Interesting details around trying to simplify MPE measurements and calculations as well.

 

 

BTW, whats the price on the Martin projector now? iirc, Kvant and RGB laser systems (and others!) do an equivalent model for a fraction of the £40k Martin were after....

 

Interesting reading, but still suggests that Scan Fail Detection to be used in the higher than MPE exposures, with less than MPE to be adhered to in situations where scan fail isnt used... Which I would totally agree with.

 

With scanfail systems, the system is designed to cut off in failure of the scanners (funnily enough), and so the possibility of a single beam above MPE hitting an audience is virtually nill (at very least very risk-assessable).

 

However, the majority of the systems WONT have scanfail detection, will have cheap scanners (more prone to overdrive and break), and therefore more possibility of above MPE emission of single beam scenario...

 

Again, off topic on the OP, but it comes down to the fact that people see the cheap lasers as a way to make an effect, and would potentially end up with dangerous occurances... You pay for laser companies because of the experience to know what you can and cant do, but the offer of a sub £400 laser running at half a watt is too inviting to your average mobile DJ or amdram group..

[mrjammy83]

Starting this topic I never thought it would go into so much depth and like The seedage has said, has enlightend me to the world of lasers and to be aware of the draw to use cheap laser systems.

 

I truly am astounded by what you guys in the laser business have to know and put into practice when at work.

 

There's me thinking of fancy ideas on the cheap and I'm sure they would work without killing or injuring someone. However I will be choosing a different effect now. Although I know when it does come round to using laser I will be fully aware of the risk and implications.

 

Please feel free to keep this thread going on anything lasers as I hope others who search these forums will be able to gain knowledge and constructive information for futur projects.

 

thanks again guys

 

james

[norty303]

Yeah, as I said, I 'won't' ;) go into the MPE thing here because there are too many variables, and different lines of thinking, even among the 'authority'.

My original ideas were about how you might achieve the effect, not how to do it with minimal budget using cheap projectors and no knowledge.

 

Glad that some people have found the article interesting reading - and possibly revealed the laserist safety page to some others - it's a great resource (imho)

[Dmills]

Scarily the actual biggest laser safety issue by far at the moment is probably class 4 laser 'pointers' (Yep, >500mw in a handheld 'pointer' with no scanners at all) that we are starting to see turning up at gigs and festivals.

 

Particularly annoying when you are trying to run a safe show and have done all the calcs, setup hard masking and beam attenuation where appropriate and generally done everything to keep people safe and along comes some numpty with a watt of 445nm in a torch housing that he got off fleabay for £300, the green version while of lower visible output is often worse as there can be a LOT of coherent IR leakage, and 1064nm is NOT eye safe.

 

While I am not exactly delighted with the 500mw disco lasers, they at least have scanners and are at least not usually right in the crowd, and there have been more incidents reported WRT pointers of excessive power then there have been with cheap ###### disco lasers.

 

Regards, Dan.