Here’s what: grabbing for the green-colored goggles when using a red laser. Testing the material of blackout curtains before hanging them on all windows in your designated laser room. Investing in ventilation, if not out-and-out exhaust ducting, before getting to work. Those are but three examples, but they all have major reasons behind them.

Before I get into the specific reasons, let me tell you, in broad strokes, why laser safety is so concerned with vision. Your eye is a sac filled mostly with water, and there’s a lens situated in the middle of it. Since lenses focus light, and since strong enough light generates enough heat to boil water, your eye is in danger of boiling. This might not be that bad on another part of your body, but your eye is connected to your brain, and the tissue connecting it is incapable of regenerating.

So, first, you should always wear eye protection when working with lasers, but moreover, you should always wear the right eye protection. Basically, red-tinted goggles will allow light from a red laser to shine right through them for the same reason that clear un-tinted eyeglasses offer no diminution of the brightness of clear sunlight. So you must use the appropriately non-corresponding eyewear with your laser, otherwise it’s as if you weren’t wearing eye protection at all.

Second, a reflective sheet of paper or- worse- a translucent one will not qualify as blackout curtains in your work area. Do some tests to see what works. There are two kinds of reflection you’re going to be dealing with- specular and diffused. Specular reflection is straight no-nonsense reflection like you’d get from a mirror (direction is the only wave property changed), but diffused is more tricky: light hitting a rough surface, especially concentrated light from a laser, still reflects, but it goes off at different angles, diffusing the light all over the place in a uniform glow that’s dangerous to the un-goggled. Hence the blackened windows.

Third, the fundamental thing to keep in mind about burning lasers is that they actually do burn material. It’s just the same effect as holding the material to an open flame, it becomes physically and chemically changed, and emits byproducts: chiefly smoke. Certain materials produce potentially carcinogenic smoke, which is why it is important to ventilate your work area thoroughly.

But these are only three precautions and three reasons behind them to give you a general idea of the cause-and-effect involved in laser safety. I cannot cover all essential safety measures in the space of this article. Every little ritual that a true hobbyist obeys is not just “being too careful,” it’s the sign that they actually know what they’re doing. We sincerely recommend you take a laser safety class before working with our products.

Here’s a very good link with an overview of laser safety, including specific calculations regarding potential hazards: http://members.misty.com/don/lasersaf.htm