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Comment by stavros | Hacker News Reader

A question I've always had: How do I know if my glasses protect against a particular laser? I'm talking about the ones in hobby CNC machines, laser hair removal places, etc, not high-powered industrial ones, where there's likely a high degree of know-how on safety already?

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Best bet is to buy two pairs and stick one in the path of the beam with a sensor or target behind it. Otherwise you're looking up charts for the materials spectral absorption in your lasers emission band

But even if the target isn't cut, that doesn't mean I won't get eye damage, does it? Or do glasses protect even if they're only a bit opaque to the target wavelength?

First of all, I take no responsibility for your safety, I'm just some person on a forum.

That being said, it's all a function of how much light enters your eye. You can look up the exposure limits of the human retina for different frequencies of light to get an idea how little is actually required to damage your eye. The target or sensor should be sensitive enough to react to that much incident light. Just putting something behind the glasses and have it not get cut is definitely not enough to indicate no eye damage.

Proper laser goggles come with ratings. Dependent on the laser wavelength, beamsize, energy/power and pulse duration. Most goggle suppliers will tell you what you need if you supply the laser specs.

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