Many people have been investigating the use of laser cutters and engravers for hobby use. While they are very useful for such tasks, the lasers themselves pose a health hazard, where the retinas of one's eyes, can be easily damaged by a laser of moderate output power that wasn't even pointed directly at the eyes.

Laser Types

Hobbyist lasers can be separated into two major types based on the frequency(wavelength) range of light that they emit:

1. Visible light lasers. Most diode lasers intended for hobbyist use are in the visible range of light. Usually specified at a certain wavelength.
2. Infra-red lasers. CO2 lasers are the most common lasers used for cutting using infra-red light.

There are other types, but these two are most commonly found when procuring lasers for cutting and engraving at the hobbyist level. The laser color is specified by wavelength in nanometers. A common wavelength for blue diode engraving and light cutting lasers is at 445nm which is a pretty cyan color:



Always know your laser's wavelength as this is critical when selecting safety glasses.


Laser Classes

The lasers are usually classed by power, and these classes roughly translate into how dangerous they are, Note that class 3B extends from "Fairly Safe" to a "High Hazard", so one should know the actual output power of the laser.

From http://www.laserpointersafety.com/laserclasses.html



Safety Glasses

Safety glasses must be worn at all times that the laser is on. It only takes a few thousandths of a second to permanently harm your eye's retina.

Do not ever stare into a laser even with safety glasses. Most of the available safety glasses are not rated for direct exposure to the eye from a laser.

The safety glasses that might have come with your laser, may not work between the two types, or even between visible light lasers of different colors, so the safety glasses obtained for use with one laser, should never be used with another laser unless the safety glasses data sheet confirms that they will block the new laser.

If you purchase safety glasses, make sure that they block the laser light for your laser. Here is a typical pair for CO2 lasers:





Note that the sides wrap around the face. This is very important as people have been injured when a laser beam entered from the side and the retina still received enough energy to be damaged.

A good set of safety glasses will give you the filter characteristics of the lenses. The Optical Density ( OD) value is how well the filter blocks out the light at a given wavelength. An OD of 3 reduces the optical power that is allowed through the glasses by a factor of 1000. An OD of 8 reduces the optical power by a factor of 100,000,000 (100 million). Note that this filter wouldn't be very good for the 445nm blue laser. The filter was starting to drop off at that wavelength, letting in the blue wavelegth :



Here is a filter that will work well at 445nm, but not for red lasers (600 to 750 nm)







Part 2 to follow

Part two will be put here.

Part three will be put here

Andy

thanks good info went in to a work shop other day laser cutting with lid up red embers glowing in the air extraction pip and a guy spraying high build primer in the door way with two guys smoking lust out side just went in to find out about some nasty chemicals got what i need but no safety info just hope that they are still there when i need some more vere good prices

This probably needs to be moves to the new laser section.

Tom

I will request it

When I first saw that sign back in 1986, it said "remaining good eye"

You can laugh about that. One incident during the first gulf war. An officer lost an eye when he decided to use binoculars to check out a location where laser range finders were being used. He deliberately only used one side of the binos so he did not end up blind.

Having worked with high power lasers for 30 years there are a ton of incidents where people have lost eyesight due to INTENTIONAL safety violations.

And not just laser cutters/engravers. Some of the newer green laser pointers can damage your eyes if you look directly at them. One physicist I know had one of the new red laser pointers when they became pen size. Someone asked him if it was hazardous and he said, 'not really, I looked into it for a few seconds and nothing happened.' Please don't do that.

Last anecdote. Medical lasers. Another accidental discovery. A scientist was doing what many of us have done, write our name using the laser beam, which you cannot see since it was infrared. You put a card or piece of wood where you aligned the beam and start moving it around based on where the burn mark is. This guy put the sample in there and was having trouble finding the beam. He turned it off and discovered some marks on his thumbnail where the laser had made several neat holes through the nail. He never felt it. He thought about it and and started research on using lasers as scalpels. Today they are used for a lot of different things depending on the wavelength, power and beam size.

DO NOT DISABLE SAFETY LATCHES.

If you have to assemble your laser make sure you assemble and test all safety functions.

Remember, all it takes is a piece of metal in the beam that reflects to your eye. Can happen easily if your alignment gets messed up, or the control system sends the gantry too far, or you leave something in there, like a metal ruler.

charlied

While I fully appreciate the safety measures outlined here, they ignore the realities of lasers that are enclosed in a cabinet with safety interlocks. Glasses are probably not needed at all if a laser is built into a completely enclosed cabinet and all interlocks are in place and operational.

I have an Epilog. Like other lasers built into a cabinet, it’s a totally different class of laser system when compared to the inexpensive open frame laser systems aimed at hobbyists. It is designed to be completely safe to operate without glasses. The door interlocks are difficult (but not impossible) to bypass. Normal operation of these enclosed systems should never require glasses with all covers closed.

On the other hand if you have a system that requires safety glasses, don't let the use of proper glasses lull you into a sense of false security. Others may enter the area with unprotected eyes. And glasses won't protect other areas of your body or surroundings from likely burns. Glasses are but one piece of the safety system. If you're running a system without an enclosure or the covers open, then it is only a matter of time before a stray emission causes damage elsewhere. Those small guards around Diode laser heads make a big difference. But they do not prevent all stray emissions.

Of course, no matter what, if you have an open system or you bypass the interlocks on a closed system, then of course glasses are mandatory. But they do not provide perfect safety.