- What is the difference between a Class 1 and a Class 4 laser, and what are the safety requirements for each?
- Which laser safety glasses should I use?
These are legitimate concerns, because even small amounts of laser light can result in permanent eye injuries, and higher power lasers can burn the skin as well. And don't be fooled into thinking that you're safe just because you can't see the laser light - infrared lasers are particularly hazardous, since the eye's "blink reflex" is triggered only by visible light!
Lasers are classified by both wavelength and maximum output power into four basic classes which categorize them according to their ability to produce damage to people operating them, from Class 1 (no hazard during normal use) to Class 4 (very hazardous for eyes and skin). The lasers used for welding, marking and cutting are generally Class 4 lasers.
When operating a Class 4 laser, it is essential to protect yourself and others in the area by using the right safety glasses and placing the laser in a room and/or surrounded by special barriers to protect bystanders from direct contact with the laser beam.
Most laser workstations used in manufacturing are built to be integrated with Class 4 lasers and house the laser beam securely in an enclosure that is both interlocked and fixed with a laser-safe viewing window. The integration of a Class 4 Nd:YAG laser for welding, for example, into a Class 1 enclosure creates a safe, Class 1 environment.
If you're investigating acquiring a system for laser welding, laser marking or laser cutting, a Class 1 laser system is the safer way to go, and doesn't impose requirements for additional personal protective equipment (PPE), such as laser safety glasses, for the operator.
If you do choose to use a Class 4 laser however, in a Class 4 environment - say, you're just doing some R&D work and don't want to go to the added expense of a Class 1 system - remember that you do need to have a room or an area outfitted with laser safety curtains/barrier as well as protective eyewear - laser safety glasses - for your operator. When it comes to laser safety glasses, there are as many styles and colors to choose from as there are fashion sunglasses, but be aware that you must be sure to choose glasses designed to protect the eyes from the particular wavelength specified on the laser. Laser glasses offer different levels of optical density (OD), for viewing protection. The higher the OD number the less light will pass through to your eyes. The OD threshold should be clearly marked on the glasses.