Class 1: Eye safe (barcode reader)
Class 2/2a: Can cause discomfort if looked at directly (CD ROM)
Class 3a/3b: Dangerous to the eyes and should not be used unless safety glasses are available (Laser pointers)
Class 4: High power-fire hazard, must wear safety glasses (research laboratories or surgical suites)
Optical power levels > 16 decibel meters (dBm) have the potential to damage fiber connectors by pitting if mated / demated while the optical signal is present