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What type of laser to use?

Lauthai

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So I am trying to do a special effect by making a laser vortex using a green laser. My plan is to shoot the laser at a mini mirror rotating on a mirror to make a vortex effect. This is illustrated in this diagram HERE

The only thing is, since it will be used for special effects, I want to make sure that it is safe for all near it. When it is reflected off of the mirror, it should only go for another foot or foot and a half before disapating, and if someone should see the laser through the mirror, I don't want it to injure their eyes. I know that the power of a laser slightly decreases when reflected off an object as well.

So how powerful of a laser should I use to make sure that it is safe incase someone looks at it in the reflection, but also is able to create the 1-1.5 foot vortex? The laser also need to be green, since color of laser does matter in this case.

Thank you.
 



Alaskan

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Wow, a huge influx of new members this week, wildly unusual. As usual though, we have to ask you to please introduce yourself and let us know a little about you in the welcome section.
 

Lauthai

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Wow, a huge influx of new members this week, wildly unusual. As usual though, we have to ask you to please introduce yourself and let us know a little about you in the welcome section.
Sorry about that, I just went and did a quick one.
 

diachi

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So I am trying to do a special effect by making a laser vortex using a green laser. My plan is to shoot the laser at a mini mirror rotating on a mirror to make a vortex effect. This is illustrated in this diagram HERE

The only thing is, since it will be used for special effects, I want to make sure that it is safe for all near it. When it is reflected off of the mirror, it should only go for another foot or foot and a half before disapating, and if someone should see the laser through the mirror, I don't want it to injure their eyes. I know that the power of a laser slightly decreases when reflected off an object as well.

So how powerful of a laser should I use to make sure that it is safe incase someone looks at it in the reflection, but also is able to create the 1-1.5 foot vortex? The laser also need to be green, since color of laser does matter in this case.

Thank you.
We need more information. Is this a public display? What other safety measures will you be taking? What's the purpose of the "vortex" (term you're looking for is probably "laser time tunnel").

Really, if you want it to be eye safe you need to restrict output power to <5mW. Which limits visibility, you'd need a lot of fog to see the "vortex".
 

CynicalBrad

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So I am trying to do a special effect by making a laser vortex using a green laser. My plan is to shoot the laser at a mini mirror rotating on a mirror to make a vortex effect. This is illustrated in this diagram HERE

The only thing is, since it will be used for special effects, I want to make sure that it is safe for all near it. When it is reflected off of the mirror, it should only go for another foot or foot and a half before disapating, and if someone should see the laser through the mirror, I don't want it to injure their eyes. I know that the power of a laser slightly decreases when reflected off an object as well.

So how powerful of a laser should I use to make sure that it is safe incase someone looks at it in the reflection, but also is able to create the 1-1.5 foot vortex? The laser also need to be green, since color of laser does matter in this case.

Thank you.

Concerning part in red...
How is it going to "dissipate" after going a certain distance? This is light we are talking about. It keeps going until it hits something that absorbs it, not after a certain distance. Honestly this sounds like a bad idea if such basics are not understood.
 

Lauthai

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We need more information. Is this a public display? What other safety measures will you be taking? What's the purpose of the "vortex" (term you're looking for is probably "laser time tunnel").

Really, if you want it to be eye safe you need to restrict output power to <5mW. Which limits visibility, you'd need a lot of fog to see the "vortex".
This would be at a public display. The person using it would be on a stage so above other people. He would not be aiming it down towards the people on the ground. The purpose would be to create a vortex affect coming from him.

Could it be exactly 5mW? And how much fog give or take would you need?
 

Lauthai

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Concerning part in red...
How is it going to "dissipate" after going a certain distance? This is light we are talking about. It keeps going until it hits something that absorbs it, not after a certain distance. Honestly this sounds like a bad idea if such basics are not understood.
Dissipate was a bad word to use. More so that it won't be visable after a certain distance. So if using a low enough power laser with not a lot of fog, then people wouldn't be able to see it after a certain distance.
 

CynicalBrad

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Honestly, the best bet is to find a certified LSO for this seeing as it is for a public performance. This kind of stuff is what they went through testing to get certified to legally do.
 

Encap

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Concerning part in red...
How is it going to "dissipate" after going a certain distance? This is light we are talking about. It keeps going until it hits something that absorbs it, not after a certain distance. Honestly this sounds like a bad idea if such basics are not understood.
Exactly. Is not something you can do with no knowledge of lasers or their safe use.

Honestly, the best bet is to find a certified LSO for this seeing as it is for a public performance. This kind of stuff is what they went through testing to get certified to legally do.
Exactly.

"U.S. regulations limit laser power used in demonstrations and light shows to Class I, II or IIIa (5 milliwatts or less). Basically this statement means any public presentation of a laser show that is above Class IIIa (5 milliwatts) must have a "variance" or permission to vary from this limit. This applies whether the laser show is done for free or for profit. (The only apparent exception is if a laser show is done in the home of the laser owner, only for the owner's family and friends."
"There are actually two variances required. One is for the lasershow-creating equipment, and the other for how it is used (audience location, barriers, etc.). A single 4-page form "Application for a Variance" (FDA form 3147; see below for a link) is filled out whether for a device or for the show."
from: http://www.laserist.org/us-regs.htm

So...Will need a variance from FDA to be used in a public display at all if over 5mW output see: https://www.fda.gov/radiation-emittingproducts/radiationemittingproductsandprocedures/homebusinessandentertainment/ucm118907.htm

"Laser radiation cannot exceed Class I limits where the audience is located." meaning 1mW or less.
"Anyone who operates laser light shows without an approved FDA variance or who otherwise violates the FDA laser safety standard may be subject to a court injunction and/or civil penalties (fines up to $300,000) as provided for in Section 360C of the Radiation Control for Health and Safety Act."
see: https://www.fda.gov/downloads/MedicalDevices/.../UCM119257.pdf

For these and other reasons you need a certified Laser Safety Officer ( LSO). You will not even be able to fill out all the forms required without one.
 
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diachi

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This would be at a public display. The person using it would be on a stage so above other people. He would not be aiming it down towards the people on the ground. The purpose would be to create a vortex affect coming from him.



Could it be exactly 5mW? And how much fog give or take would you need?

Then you either need to hire a LSO (Laser Safety Officer) and get a variance from the FDA/CDRH or use a <=5mW laser.

I'm not sure how to quantify fog like that... So I'll simply stick to lots. You'll also need very low ambient light levels.



 




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