Laser safety goggle recommendations

July 2, 2023 8:48 PM

I'll be working with a home-built laser cutter and the potential for wacky mishaps makes me think this isn't the time to skimp on safety equipment. What would be the industry standard to work with a 450 nm laser?
posted by Tell Me No Lies to Technology (5 answers total)

First, calculate the optical density you need.

Then search a laser safety goggle vendor such as Phillips Safety, ThorLabs, etc. for your wavelength and optical density spec. A high Visible Light Transmission value, VLT, is a big plus. I mostly have the style that fit over regular glasses but now use a 1.75x Headband Flip-Up Magnifier instead of wearing my 1.5 diopter reading glasses.
posted by tinker at 9:27 PM on July 2, 2023

Personally, I prefer specialist suppliers like those linked above, or else single-purpose companies like Lasersafety. Pursuant to remarks above, for the love of god remember that things can come at you from unexpected angles -- my laser is fully enclosed and cannot operate unless the interlocks are engaged, but a lot of blue diode lasers are not so secure and can potentially blind you while you're looking in an unrelated direction if you're unlucky so if you're using a system without interlocks consider getting fully-enclosed goggles rather than "glasses".

...but hey, I'm paranoid that way, YMMV.
posted by aramaic at 10:44 PM on July 2, 2023 [6 favorites]

I'm a laser physicist, and I'll start by saying that I don't really recommend building your own laser cutting setup. Commerical systems are (somewhat) safe because they have layers of engineering controls (like the interlocks aramaic mentioned) that separate you from the operating laser beam. If you are building a setup, you'll be starting off with some sort of unsecured death ray laser, and will have to build in all that protection without blinding yourself in the process. To give you some sort of idea, to have a class 4 laser in our lab (and ours are only ~5 W), we need: it to be registered with a national safety regulator, and inspected yearly; to be in a locked lab; to have an additional interlock on the door that turns off the lasers when the door is opened without disabling the interlock; three levels of laser safety training for anyone with access; laser blockout curtains around each experiment; containment to keep the laser beam on the table; laser goggles; risk assessments and safe working procedures.

Even with those protections, we would not set up an experiment with a beam at full power - so you also need a power meter, beam dump, and some way of (safely!) attenuating that light down below 100 mW. I suggest as a starting point you get hold of a good laser safety course and the laser safety standards document for your country/region ( e.g. in Australia, AS/NZS 2211.1:1997) .

Thorlabs, in addition to selling laser goggles, is not a bad place to start learning about laser safety - they have put a fair bit of work into providing information and tutorials alongside their products. When you are dealing with very high power laser safety gets a bit more complicated, because even scattered reflections off surfaces (like your wedding ring or a screwdriver) can cause damage, so you have to think more carefully about what materials could intersect the laser beam.
posted by neatsocks at 5:24 PM on July 3, 2023 [1 favorite]

I have a coworker that has tiny dead spots all over his retina from an accidental scattering @ 400-430 nm. Listen to neatsocks.
posted by JoeZydeco at 5:43 PM on July 3, 2023 [1 favorite]

Response by poster: Thank you for the pointers on safety. The initial design calls for a completely opaque cabinet with the power for the laser run through the door latch, but that does raise the question of how long a beam will continue to be emitted after power is turned off. Even a couple of milliseconds could lead to a bad day.

If I need to monitor progress I’ll put a camera in the enclosure. The goggles are a last line of defense — if at any point the laser has power and is not completely enclosed then something will have gone very wrong.
posted by Tell Me No Lies at 9:21 PM on July 3, 2023 [1 favorite]