Safety might seem like a boring and tiresome topic, and really most of it is little more than common sense. But common sense is not always as common as it ought to be, and sometimes we can get a little carried away with the fun stuff, that we forget what’s important. So, until replacement eyeballs are cheap and effective, let’s take some time to think about laser safety.
General Laser Safety
Safety guidelines that apply to lasers of all power classes:
- Never, under any circumstances, look into the beam of any laser! I don’t care if you have safety glasses, or if it’s only a 2mW keychain pointer. Don’t do it! For one thing, don’t get into a habit of looking into the beam with cheap pointers, you might someday be working with a more powerful laser. Laser Safety goggles protect against accidental exposures, they aren’t meant for direct viewing of the beam. There’s just so many things wrong with the idea of looking into the laser beam. Don’t do it.
- Never, under any circumstances, aim the beam of any laser at another person or animal! See above. It’s foolish to risk your own eyeballs, it’s criminal to risk someone else’s.
- Never, under any circumstances, aim the beam of any laser at a moving vehicle! This is in fact a criminal offense in most parts of the world. It’s also idiotic, for the reasons listed above.
- Keep your Laser(s) out of the reach of children! Or, any irresponsible people, in fact. Don’t leave your laser where your child, or kid brother, will find it. And don’t hand it around at your drunken frat party. You might know all the safety rules, but what are the odds that everyone else does too?
Class 3b Laser Safety
Safety guidelines that apply to class 3b lasers — in addition to the guidelines mentioned above:
- When using your laser outside, do not aim it at any buildings or areas where people may be. If you aren’t sure that an area does not contain any people, then do not aim your laser at it.
- Higher-Powered Lasers are not toys! Lasers above 5mW in power are capable of burning and blinding. They are tools and should never be treated in a careless or irresponsible fashion.
- Laser Safety Goggles are strongly recommended. If you plan on doing tricks such as burning matches or balloons, or melting tape or plastic, or even setting up a lightshow, you should invest in properly rated Laser Safety Glasses. Staring closely at the intense light while doing tricks, or working with mirrors and other reflective surfaces, creates the risk of specular reflections. Safety glasses can help protect your vision from accidental exposure.
- When using your laser indoors, be careful of where the beam is terminated.Higher powered lasers can cause some materials to smoulder. Specular reflections are also possible, from many household surfaces.
About Laser Eye Damage
Lasers above 5mW in power, are increasingly more dangerous to your vision, as the power goes up. At 100mW for instance, a laser can cause damage to your eye faster than you can blink – in only 1/1250th of a second.
Damage, however, does not always mean instantaneous total blindness. You may see a bright flash then your vision returns and you think you have been lucky. Eye damage can be cumulative, and can go undetected until it is too late.
The brain is very good at hiding blind spots. For example, all of us are born with two 10-degree blind spots, one in each eye. We don’t notice them because the brain fills in the missing data with what the opposite eye sees – or if you close one eye, the blind spot is filled with what’s around it.
So while you may not immediately see black spots, you may find areas of vision become blurry or fuzzy. This kind of damage will accumulate with each ‘accident’ or ‘close call’, and does not heal.
About Laser Safety Goggles
Laser Safety Goggles (or Laser Safety Glasses) are more than just pretty coloured plastic. Properly rated Laser Safety Glasses will indicate what wavelength(s) they are designed for, and how much protection they offer (Optical Density, or OD).
Laser Safety Goggles are wavelengh-specific. Goggles that protect your eyes against one wavelength do not necessarily protect against another. For instance, goggles that protect against red lasers (630 to 670nm) usually offer little or no protection at blue and green wavelengths (470-550nm). Multi-line goggles do exist, which protect against multiple wavelengths, but they tend to be much more expensive.
Real Laser Safety Goggles tend to be a bit more expensive than you might expect. This is because they are specially designed to try to meet two conflicting goals: they have to stop the intended wavelength of laser light from passing through, but they also have to let as much of all other wavelengths of light through. Laser Safety Goggles are designed to absorb their intended wavelength rather than reflect it, so as to minimise the possibility of additional stray reflections around.
The companies that sell Laser Safety Goggles test their goggles, some provide certification, and that means you know you can trust your eyesight to them.
Sunglasses, welding glasses, are not good alternatives. They tend to reduce overall light transmission, making everything ‘darker’ to you. This causes your pupils to dilate so you can see better. Meanwhile, sunglasses and welding goggles may not even absorb well at the particular wavelength of your laser. So they can be doubly-harmful, dialting your pupils while not substantially protecting your eyes.
Laser Safety Goggles can protect and save your eyesight if you should be accidentally exposed to laser radiation. They are never intended for direct viewing of the beam.