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Specific Diffusion Question

JAAM

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Joined
May 26, 2020
Messages
3
Points
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Sorry for the likely repeat but I could only find vague answers.

For some background I built a 2W 445nm laser a few years back and religiously wear goggles when using it for anything other than pointing it at an empty clear sky.
I understand that diffraction can be a safety hazard at high powers and is based on distance from the laser "dot". I keep seeing conflicting information on whether or not wavelength matters.

I'm about to be putting together a RGB laser for fun and show and was curious what is viable from a safety perspective.
The RGB module I found has 2 wattage options

300mw (638nm@100mw, 505nm@100mw, 450nm@100mw)
and
800mw (638nm@180mw, 505nm@100mw, 450nm@520mw)

I understand that neither of these are safe for direct eye exposure however I was wondering whether the 800mw variant would be a diffraction hazard at 5ish ft from the dot.

Ideally I'd like to use the more powerful module for a more vibrant color but if everyone needs goggles on it defeats the point of the build.
 



Mattronium

Active member
Joined
Dec 12, 2012
Messages
735
Points
43
Do you mean reflection instead of diffraction? For the most part, for visible lasers, the danger is from power (and power density, irradiance) not wavelength.
Aside from the obvious danger of a direct hit to the eye, the second danger is from specular reflections. The specular reflections depend on what surface the laser hits. Are you planning on using the module like a pointer or mount it/keep it mostly stationary?
 

JAAM

New member
Joined
May 26, 2020
Messages
3
Points
3
Sorry to clarify I was asking about the safety of looking at the dot on a non reflective surface from 3-5+ feet away
Ideally the laser would be a large battery powered handheld
 




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