Lasers are a potential safety hazard in the laboratory, and Duke’s Laser Safety Program is designed to address that hazard, specifically for Class 3b and Class 4 lasers, which pose the most serious risks. Under Duke policy, a faculty member responsible for such a laser is called a Principal Laser User (PLU). The PLU is directly responsible for the safe use of the lasers under his or her control, and must complete the online Laser Registration Form for each Class 3b or Class 4 laser.