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New halloween store display... safe?

marks47

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Hi all. Just wondering if anyone has come across a 'display'/'novelty' laser setup that shoots a blue wavelength diode module through a line generating lens that's safe at eye level? I came across this at the halloween store today. They'd created a little 'horror hallway' type thing with half a dozen diode modules mounted in some kind of clamping rigs that also had photo-diode switches of some sort that triggered the displays and sounds. It was kind of cool... BUT, they were all at around 4 feet, running horizontally. I saw one kid walk straight into it at eye level...

attached image is the best my iphone could do at these lighting levels/wavelengh. I couldn't quite get the details off the sticker, as I didn't want to get kicked out of the store quite yet (taking it out of its mounting system)...

I realize the line lens diffuses the power, but I'm not sure to what level it might be safe... None of the modules are more than 3 feet away if you're in the little hallway they created for this.

I was a little concerned, and now a little bit more because they didn't sell them, and I haven't found a specific product that generates the same effect...

Does this scream out, "not safe" to anyone? Or anyone familiar with this description of a known product for public spaces?
I'll probably go back and get a little more aggressive about getting the label info soon.
 

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steve001

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Hi all. Just wondering if anyone has come across a 'display'/'novelty' laser setup that shoots a blue wavelength diode module through a line generating lens that's safe at eye level? I came across this at the halloween store today. They'd created a little 'horror hallway' type thing with half a dozen diode modules mounted in some kind of clamping rigs that also had photo-diode switches of some sort that triggered the displays and sounds. It was kind of cool... BUT, they were all at around 4 feet, running horizontally. I saw one kid walk straight into it at eye level...

attached image is the best my iphone could do at these lighting levels/wavelengh. I couldn't quite get the details off the sticker, as I didn't want to get kicked out of the store quite yet (taking it out of its mounting system)...

I realize the line lens diffuses the power, but I'm not sure to what level it might be safe... None of the modules are more than 3 feet away if you're in the little hallway they created for this.

I was a little concerned, and now a little bit more because they didn't sell them, and I haven't found a specific product that generates the same effect...

Does this scream out, "not safe" to anyone? Or anyone familiar with this description of a known product for public spaces?
I'll probably go back and get a little more aggressive about getting the label info soon.
You provided absolutely no information to make a judgment.
 

Cyparagon

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It depends on the power, the beam angle, the beam profile, and the distance from the source.

One possibility: 1W top-hat profile at 90 degrees (1571mRad)
Pupil max diameter is something like 8mm, and diode lasers are often 4mm initially.
absorbedPower = 8mm/(1W*(4mm+1571mRad*distanceInMeters))

at 1 meter, 1W is spread to 1575mm line. Of which, 8mm is .5% or 5mW. Any closer would be over 5mW exposure. Inverse square law doesn't apply here because it's a line, not a beam, so the relation is linear. 1/2 meter is 10mW, 2 meters is 2.5mW.

It also goes without saying, sticking your face right against the aperture is a bad idea regardless of power. But several feet away and your blink reflex makes this pretty harmless. I also doubt the blue would be as high as 1W in the first place.

(I haven't done this sort of math in a while so please correct any mistakes.)
 
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kecked

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5mw is only for 0.25s accidental exposure. Really the mpe is 2.5mw. Would depend on how the line was made as well. CW or scanned. It could be made safe if you used a large enough divergence on the beam. I’d aim it down on n angle too. That keeps it out of eyes and actually makes the effect more visible. You could also employ a mask
 

Cyparagon

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I think you missed the part where I mentioned blink reflex being a part of this.

I think you also missed the part where OP said this was a lens, not scanned.
 

marks47

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I don't think the blink reflex is factored into the design of the installation in that the whole point is to make a cool display with fog, so to create the flat "plane" effect. I'll go back tomorrow and see about getting my fingers in there and take the module out of the clip/stand it's using. I hate to cause trouble or more work for the owner of the store, but I hate more seeing the kids I saw going in there, right at the level of the plane of light being emitted. Thanks guys. I'll report back with better information.
 

RedCowboy

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I walked into a music store and the guy switched on the show lights including some green scanning lasers and that dam thing hurt, it was way to bright and scanned me right in the eyes, I'm not blind but I didn't like it.
 

marks47

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Update: I went back and mostly chickened out. I took a couple more pictures of the modules, but there are no markings that I could see on them other than "Laser Aperture: Avoid direct eye exposure" and something else written in chinese. I wasn't brave enough to completely disassemble their stuff. :(

I guess the question I should have asked in the first place: What (near-blue) nm and mw laser specs would YOU (anyone) use, with which line lens, in an installation where kids are going to be looking straight into it? (Assuming you wanted it to be safe)
 

steve001

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Update: I went back and mostly chickened out. I took a couple more pictures of the modules, but there are no markings that I could see on them other than "Laser Aperture: Avoid direct eye exposure" and something else written in chinese. I wasn't brave enough to completely disassemble their stuff. :(

I guess the question I should have asked in the first place: What (near-blue) nm and mw laser specs would YOU (anyone) use, with which line lens, in an installation where kids are going to be looking straight into it? (Assuming you wanted it to be safe)
That can be a long involved answer. Try this. Google "blue laser Halloween display" to see if what you saw shows up.
 

kecked

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Try using an led stage light and see if you can fake it. There is no lase4 in blue I’d shine in a kids eyes at all. Even the leds blues are not so hot for your eyes. Yo7 want something like an elipsoidal you can focus. Many cheap led flashlights really have a tight beam. Maybe make a line of those.
 

marks47

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...There is no lase4 in blue I’d shine in a kids eyes at all. Even the leds blues are not so hot for your eyes....
You kinda made my point for me...
I did not think from the beginning that there IS a safe method of doing what they're doing. I am not intending to build my own.

Thanks!
 

marks47

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That can be a long involved answer. Try this. Google "blue laser Halloween display" to see if what you saw shows up.
Definitely tried to find one. Couldn't. The closest I came was to finding similar modules with the line lenses already attached. Wasn't on a site intended for fun/display purposes.
 




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