Some questions regarding LC-1000 or LaserCube from Magnum Lighting Technology Co and more questions regarding RGB laser safety

[Dunning]

I am looking into getting an LC-1000 (2W version) or LaserCube projector, which now appears to offer global distribution including shipping to the US from Magnum Lighting Technology Co. This unit can output 1400mw at 455nm, 400mw at 520nm and 450mw at 637nm. The beam divergence is 4.0mm / 1.0mrad.

If I understand and did all the math correctly, I'll need a minimum of 4.0 OD safety glasses (3.155 OD at 1400mw, 2.611 OD at 520nm, 2.662 OD at 635nm) to avoid instant eye damage if operating at full power (like when it is engraving/burning). What I have zero understanding of is how these wavelengths may combine, interfere or behave outside the 445-637nm range. Would I need protection beyond 637nm range, and would I need to worry about wavelengths below 445nm? I do understand that lasers (like cheap DPSS green lasers) often leak IR radiation so having some protection into the IR range is always a good idea.

Additionally, I am wondering if this device can actually legally be brought into the united states? It does appear to meet US safety regulations (key, interlock, beam block, led indicator), but it might not have an up to date variance (21 CFR 1040.10) which the FDA (at regulations.gov) requested from them back in Jul 2, 2019 (FDA-2019-V-1682-0003). I don't see that the variance was declined though (status still shows as open)? It did have that variance approved back in 2018 (FDA-2018-V-2994-0003) so maybe that got extended? Also that variance is for their 1W version, so I don't know if it applies to the 2W version, but both lasers are considered to be a LC-1000. If I were to order this, would it make it past customs if inspected, and would a variance for a public lightshow get approved in the US if I managed to set it up correctly and safely?

One last question regarding diffuse reflection safety. If I understand all the math correctly again, this unit has a NOHD distance of 1742 feet (531m) at full power. Assuming there is absolutely no surfaces which would risk a specular reflection, what might be a NOHD distance to protect yourself from diffuse radiation when this laser is operating at full power against a surface like dirt or wood? I understand that you should ALWAYS wear eye protection, I am just looking for an estimated NOHD distance regarding diffuse reflections. I will not be one of those people that assume "bad stuff only happens to other people" or have optimism bias regarding laser use.

 

[LaserMicroscope]

It’s great that you’re concerned about safety, that’s the right attitude to have! I’m not an expert on anything, but I’m especially not an expert on the law, so I’ll try to confine myself to the science.

Generally speaking, don’t worry about the wavelengths interacting. That’s not really how the physics of light works in most cases fortunately. While waves can interact, the type of interactions we usually think of don’t happen from two separate systems of waves in air. A lot of the “frequency changing” effects that happen with lasers like harmonics happen within a single beam, not from the interaction of different beams from different sources. If your goggles are credibly rated to protect from the wavelength of the individual diodes, you’ll be fine. (Smart to remember about the IR leakage potential though!)

As for diffuse reflections, that’s a more complicated answer. Different wavelengths are going to be absorbed/scattered differently by your surface. As I’m not an optics expert, my naive approach would be based on power density of the spot - you could calculate based on the divergence of the beam how the power density changes with distance, and compare that density to the spot of a known laser (or laser classification) with acceptable diffuse reflections. I’m certain someone else on here will either have a better method or even a hard answer for you, but if I was without information that’s how I’d go about generating an estimate!

 

[paul1598419]

These projectors are made to be seen. That means the diffuse reflections are not inherently dangerous. I can tell you there is nothing brighter mW for mW than my 1100 mW 520nm green laser or my 532nm 1300 mW one. I look at the diffuse reflections of these all the time. Since this is a PJ you are going to have these diffuse reflections spread over greater distances. If you wear goggles you won't get to see the images these projectors are made to show.

 

[Dunning]

It’s great that you’re concerned about safety, that’s the right attitude to have! I’m not an expert on anything, but I’m especially not an expert on the law, so I’ll try to confine myself to the science.

Generally speaking, don’t worry about the wavelengths interacting. That’s not really how the physics of light works in most cases fortunately. While waves can interact, the type of interactions we usually think of don’t happen from two separate systems of waves in air. A lot of the “frequency changing” effects that happen with lasers like harmonics happen within a single beam, not from the interaction of different beams from different sources. If your goggles are credibly rated to protect from the wavelength of the individual diodes, you’ll be fine. (Smart to remember about the IR leakage potential though!)

As for diffuse reflections, that’s a more complicated answer. Different wavelengths are going to be absorbed/scattered differently by your surface. As I’m not an optics expert, my naive approach would be based on power density of the spot - you could calculate based on the divergence of the beam how the power density changes with distance, and compare that density to the spot of a known laser (or laser classification) with acceptable diffuse reflections. I’m certain someone else on here will either have a better method or even a hard answer for you, but if I was without information that’s how I’d go about generating an estimate!

That is very good to hear regarding that the wavelengths won't interact in that way.

These projectors are made to be seen. That means the diffuse reflections are not inherently dangerous. I can tell you there is nothing brighter mW for mW than my 1100 mW 520nm green laser or my 532nm 1300 mW one. I look at the diffuse reflections of these all the time. Since this is a PJ you are going to have these diffuse reflections spread over greater distances. If you wear goggles you won't get to see the images these projectors are made to show.

My primary concern was with the projectors burn/engrave function. It measures 1900mw on a laser power meter if it focuses all 3 beams and it'll burn through a plastic cd case in about 4 seconds.

 

[paul1598419]

I would not use an RGB laser to engrave with. If you want to engrave there are many better single wavelength choices that work much better for that and are, frankly, much better suited for that purpose. This is ~2 watt projector from what you've said here. It should be used for that purpose.

 

[LaserMicroscope]

I would not use an RGB laser to engrave with. If you want to engrave there are many better single wavelength choices that work much better for that and are, frankly, much better suited for that purpose. This is ~2 watt projector from what you've said here. It should be used for that purpose.

^^ absolutely. The "burn" feature on the lasercube is more of a gimmick anyway - it can only stay on for a few seconds - and frankly, you'd get tired of using it. Burning with lasers is fun if you're safe about it, but using a laser projector is definitely not the way. Fortunately, you need to specifically enable this function, as in normal operation it doesn't output that much power. In this normal mode, you'll be unlikely to encounter any issues with the diffuse reflections, assuming you follow the operating guidelines.

 

[Shakenawake]

IR light from unfiltered dpss lasers applies mostly to 532nm lasers. 520nm indicates to me that it is a diode laser, not a dpss, which is a good thing.