Laser Classifications and Their Requirements

Class 1 lasers are incapable of causing an injury during normal use because they have very low power or because the beam is fully enclosed. Labeling is not required. Examples include laser printers, highway patrol Lidar, and DVD players. There are also class 1 laser systems enclosed with high powered class 3B and 4 lasers within. The enclosure is designed to prevent access to the laser beam, preventing any hazardous exposure. These systems commonly integrate interlocks which are designed to shut down the laser if the enclosure is opened. A fully enclosed system with proper labelling and safeguarding will fulfill all requirements of a class 1 laser and can be operated in an enclosed manner with no additional controls. Operators of class 1 lasers are not required to attend Einstein’s Laser Safety Training course; however, these operators may request to attend the training if they would like.

Class 2 are low power lasers (output must be less than 1 milliwatt) that must be visible (wavelengths between 400 nm – 700 nm). A human’s natural aversion response time of 0.25 seconds to bright light will cause personnel to blink before a class 2 laser can produce an eye injury. However, if personnel overcome the aversion response time and stare directly into the beam injury can occur. Examples include some laser pointers, digital thermometers, and laser scanners such as bar code readers. A caution label and indicator light are required. Operators of class 2 lasers are not required to attend Einstein’s Laser Safety Training course; however, these operators may request to attend the training if they would like.

“M” stands for magnification. Class 1M and 2M lasers are class 1 and 2 lasers when viewed with an unaided eye. If magnifying optics or collecting optics are used, more light enters the eye increasing the hazard. “M” classes usually apply to expanded or diverging laser beams. Examples include some binoculars, telescopes, and magnifiers. Operators of class 1M or 2M lasers are not required to attend Einstein’s Laser Safety Training course; however, these operators may request to attend the training if they would like.

Class 3R lasers are “marginally unsafe” medium powered lasers limited to 5 milliwatts. The aversion response time is not adequate protection for direct exposure of a laser beam to the eye; avoid direct eye exposure. There are no hazards from diffuse viewing or skin exposure. Examples include laser scanners, alignment devices, and certain laser pointers. Specific signage is required in the laser area. Operators of class 3R lasers are not required to attend Einstein’s Laser Safety Training course; however, these operators may request to attend the training if they would like.

Class 3B lasers can be visible or invisible and are hazardous for direct eye exposure to the laser beam and are capable of producing minor skin injuries when operating near the upper power or energy limits of the class. Diffuse reflections are generally not hazardous unless the laser is near the class limit (upwards of 500 milliwatts) and the diffuse reflection is viewed from a close distance, however most class 3B lasers do not produce diffuse reflection hazards. The maximum average power for a continuous wave or pulsed 3B laser is 0.5 watts. For pulsed 3B lasers the maximum pulse energy depends upon the wavelength, such as visible 3B lasers having a maximum pulse energy of 30 millijoules (mJ). For wavelengths between 1050 – 1400 nm the maximum pulse energy increases to 150 mJ per pulse. Ultraviolet and far-infrared wavelengths have a limit of 125 mJ. Examples include entertainment lasers used in light shows, certain medical and therapeutic lasers, lasers used in research, and high-powered laser pointers.

Class 3B laser operators at Einstein must attend Einstein’s Laser Safety Training course and be authorized to operate the laser. Other requirements include specific signage to be posted in the laser area, written SOPs, recordkeeping, annual inventory, safety equipment such as eyewear and containment, and periodic inspections from the EH&S Department and potentially the NYS Department of Labor.

Class 4 lasers are the most powerful of all the classes and require application of the most stringent control measures. Continuous wave class 4 lasers are high powered having more than 500 milliwatts of power. They are powerful enough that diffuse reflections are a hazard. These lasers are both an eye and skin hazard for both direct and scattered exposure. They are also a fire hazard and may produce Laser Generated Air Contaminants. Examples include lasers used in industrial cutting, welding, scientific research, and certain medical procedures.

Class 4 laser operators at Einstein must attend Einstein’s Laser Safety Training course and be authorized to operate the laser. Other requirements include specific signage to be posted in the laser area, written SOPs, recordkeeping, annual inventory, safety equipment such as eyewear and containment, and periodic inspections from the EH&S Department and potentially the NYS Department of Labor.