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Liquid Sky with 150mw

dogfishmcfiz

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Ok, so somewhat related to my first post about my eye anxiety, I got ordered this 150mw 405nm line lens laser to use as a liquid sky effect over dance floors. I realize I probably should have gotten a lower powered laser and made a scanner, but I figured this looked like a relatively easy way to produce a similar effect.

My question is with that power of laser, what type of surface should I have the beam terminating on so that if people on the dance decide to look up at the line, they will be 100% safe. Should I get some blackout curtains/material and apply that to where the line will be projecting? I plan on keeping it on for like 10-15 minutes at a time in a fixed position well above everyone's heads.

Should I just cut my losses and make a scanner with a lower powered laser? Would love any advice you could provide, very new here but want to make sure I do everything as safe as possible!

:beer:
 



swamidog

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405nm is pretty much the worst choice of lasers for this application. the human eye is very insensitive to that wavelength so you need lots of power to get good beam effects. a better bet is to use green (532 or 520 are the most common). that way you can turn the power way down for the same amount of perceived brightness.

i wouldn't be concerned about looking at a terminated line of the wall with 150mW of any wavelength. just remember to keep the beam at least three meters over the dancers heads.

what you didn't specify was the application. if this is a disco in your house, you're likely to be fine. if this is a public venue, you're setting yourself up for legal trouble. NY has some of the most restrictive laser laws in the country and without an operators variance, a NY license, and a varianced projector you're looking at a world of problems if you get inspected.
 

dogfishmcfiz

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Lol yeah I realized that shortly after ordering it. A quick look at the perceived brightness chart made that exceedingly obvious.

I would only be using this at events that were not at established venues in NY (usually basements and apartments), but that's a good thing to keep in mind. Could you send over some recommended green lasers that could do the job at lower powers?

I do plan on getting my NY license and operator's variance eventually if I get seriously into this but for now this is just something I'm working on for small parties with friends. Was inspired by Bossa Nova Civic Club in Bushwick who uses a lot of fixed 405nm reflecting directly of a mirror back to right above the laser that makes a really nice subtle effect with all the fog they have (tried to find a picture but couldn't). I mostly use LEDs in my designs.
 

hakzaw1

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laserbeam bounces beamshapes onto a GITD 'screen' use an old speaker and spring--JBWeld or E3000-- best use for 405..
no good for tunnel or LS.. as Swammi sez--green is best.
 

Cyparagon

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If you do the calculations and measurements, you'll find a laser of this power through a line lens is eye-safe at any distance beyond a few feet. By eye-safe, I mean does not exceed MPE. If you ensure the first several feet of the projection are not accessible, and verify the device is actually putting out the power you think it is, it is safe.

Of course, the thing is nearly invisible as a solid beam, so a liquid sky will be pretty useless at this wavelength.
 

dogfishmcfiz

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Cool thanks for all the responses. I will probably just work on swapping out the line lens for a dot one and use it for other purposes.

laserbeam bounces beamshapes onto a GITD 'screen' use an old speaker and spring--JBWeld or E3000-- best use for 405..
no good for tunnel or LS.. as Swammi sez--green is best.
I understand what you mean by the GITD screen, would you mind elaborating a bit about the old speaker and spring part?
 

paul1598419

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I can't say for sure, but I think he means to attach the laser with a spring to the voice coil of the speaker and as music is played through the speaker it will cause the laser to oscillate with the voice coil and will fluoresce the GLID screen.
 

10fenny

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I've seen it where to attatch a mirror from the outer frame to the center cone! When the beats hit it will actuate the mirror when the laser is pointed at it. Yet to try it though
I have projectors now!!
 

paul1598419

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Yeah, I've seen a mirror attached to the center of a speaker before, to move a laser's beam pointed at it in sync with the music. It is a poor man's projector. :p
 




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