Surface finish on SUS304 to prevent laser reflection 1

[Finglas]

Does anyone know what type of surface finish/treatment on SUS304 would prevent reflection of a laser?

 

[Finglas]

Here's the unit we'll be using - a Keyence ML-Z9520A. It's only working at 30W. Sorry, should have posted sooner. Class 2 as opposed to class 4. My mistake.

 

[BrianPetersen]

Laser marking unit which uses a CO2 laser (far infrared). As long as you are not looking straight into the beam, and as long as whatever it's hitting isn't acting like a near-perfect mirror to far infrared, it won't be a "hazard" as long as you are more than a few hundred millimeters away from whatever it's hitting.

I found out the hard way that if the laser marking point is directly visible, even from a few meters away, it's uncomfortable and people will complain about it even if the numbers say it's not a "hazard" (we had a proper LHZ calculation done for that one). It's like looking at a TIG welding arc - a tiny but extremely brilliant point. It isn't the reflected laser radiation that is the problem ... it's the visible light coming from the tiny hot spot.

Anything that blocks direct visibility of that point will prevent that. Weld curtains, simple enclosure, orienting the impact point so that it's not directly visible, etc. You don't have to concern yourself with multiple reflections ... assuming you are not dealing with near-perfect mirrors.

 

[IRstuff]

"it's the visible light coming from the tiny hot spot"

It's the UV coming from the hot spot that's the hazard

TTFN (ta ta for now)
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[BrianPetersen]

Right, but it's not the reflected laser radiation that you are trying to stop, it's secondary light being emitted from the hot spot, which isn't coherent laser radiation, and which dissipates with the square of the distance, and which can be blocked by just about anything including normal weld curtains.

 

[MacGyverS2000]

The laser radiation from a CO2 laser is far infrared, and the reflected laser radiation won't do much,

Woh, Nelly! You better believe reflected radiation can do some serious damage. I agreed with everything else you said, but reflections can turn nasty...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[BrianPetersen]

"Can" turn nasty, yes. That's what a LHZ calculation is for.

Or just close the whole thing in and make sure the laser doesn't work unless the enclosure is closed and no one is in it.

 

[handleman]

Not sure what a LHZ calc is. Maybe NHZ?

 

[EdStainless]

You only have two options, absorb the energy and have a way to cool the target, or scatter it in so many directions that none are dangerous.


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P.E. Metallurgy, Plymouth Tube

 

[IRstuff]

LHZ short for Laser HaZard calc; USAF's software is called LHaz

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[drawoh]

Finglas,

Any time I have worked around high powered lasers, someone has been designated as Laser Safety Officer (LSO). Do you have one?

--
JHG

 

[moon161]

Related story: I was asked to design a laser safety shield for a multi-kW cutting laser (free standing 10' x 10' 1/8" steel wall) and an enclosure for the acrylic test plug they shot the laser at. 1/8" because the engineers wanted time to find the e-stop if the beam became uncontrolled. So I drew up the wall and detailed a nice sheet metal box with a door and an aperture and a mount for the the hair dryer cooling air blower to hang off of it, badgered the welders as requested, etc.

I didn't see the test, but I'm told that after they had problems with flames shooting out the aperture, they just put the test plug on top of the box and wore the special sunglasses.