💾 Archived View for freeside.wntrmute.net › log › 2021 › 20210514.gmi captured on 2023-09-28 at 15:48:11. Gemini links have been rewritten to link to archived content
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In the last post, I mentioned that I bought a laser. Well, I bought another just to compare.
Both laser listings look pretty much identical: 5mW lasers, same housing. 5mW *should* be eye-safe. The only real difference should be the colour: 445nm for the blue laser, and 532nm for the green laser.
/img/log/20210514/two_lasers.jpg
They look identical. The one on the left is the green laser, the one on the right is the blue laser. The difference becomes apparent when I break out the laser power meter (LPM).
The green laser is actually between 55-65mW, depending on a few factors. Either way, it's decidely not eye-safe anymore. A class 3R laser tops out at 5mW, which has been determined to be the limit where the blink reflex will keep your eye from getting injured. It's safe with a restricted beam viewing. At 55mW, you've got a class 3R laser which has to be equipped with a key switch and safety interlock. You might be okay if the beam is shining at a matte surface.
The blue laser is over 1W of power, which puts it at twice the limit for a class 4 laser. Class 4 lasers can burn the skin or cause "devastating and permanent eye damage as a result of direct, diffuse, or indirect beam viewing." They pose a fire risk for sure. Most definitely not a safe laser.
The moral of the story is be careful when you buy lasers from a sketchy source, like eBay. Always take proper laser precautions; I wore a set of OD5 laser glasses that covered the blue and green spectrum; they will reduce the light from the 1W laser to well under a milliwatt at my eye, which is well within the safety limits.
Another word of caution about the eye protection. I was curious how well the eye protection that came with the 1W laser would protect against laser damage so I ran an experiment with the LPM. Note that the batteries are running low at this point, so the laser isn't even at full power.
Fair warning, the gif is large (~135M), so if you're on a low-power machine, maybe skip this.
Don't skimp out, get a real pair of eye protection. If you've never done much with lasers besides a laser pointer, build your way up and get comfortable working with them.
