Environmental Health and Safety

Laser Safety Classification

Laser Registration

PIs must register all Class 3R,3B, and 4 laser systems with the LSO prior to first use, when relocating to another space, or after significant changes of the laser system. Please use the EHS Safety Management System for each class 3R, 3B or 4 laser.

FDA Regulations

Laser safety standards are derived from government mandated regulations and voluntary standards. Safety rules governing the manufacture of lasers are established by the Federal Government. Laser products manufactured after August 2, 1976 must conform to performance standards established by the Food and Drug Administration (FDA), (21 CFR 1040.10). The standard requires that lasers be properly classified and labeled by the manufacturer. Thus, for most lasers, measurements or calculations to determine the hazard classification are not necessary. In addition, the standard establishes certain engineering requirements for each class and requires warning labels that state maximum output power. The performance standard regulates the manufacturer of lasers but does not address the safe use of lasers.

OSHA Regulations

OSHA Regulations (29 CFR 1926.54 and 102) specify generalized rules for the safe use of lasers in the construction industry. These include user training, posting and labeling requirements, laser safety goggles, and maximum exposure intensities. Requirements for the use of laser goggles in general industry are specified in sections 1910.132-133. The safe use of lasers in general industry (including research laboratories) is covered under OSHA's General Duty Clause which states that employers must furnish employees a place of employment that is free from recognized hazards that are likely to cause death or serious injury. Extensive recommendations for the safe use of lasers have been developed by the American National Standards Institute (ANSI Z136 series).

Since August, 1976 manufacturers have been required by Federal law to classify lasers. If the class is not known, one can be determined by measurements and/or calculations. Lasers are classified according to the ability of the primary or reflected beam to injure the eye or skin. The appropriate class is determined from the wavelength, power output, and duration of pulse (if pulsed). Classification is based on the maximum accessible output power. There are four laser classes, with Class 1 representing the least hazardous. All lasers, except Class 1, must be labeled with the appropriate hazard classification.

Laser Registration

PIs must register all Class 3R, 3B, and 4 laser systems with the LSO prior to first use, when relocating to another space, or after significant changes of the laser system. Please use the EHS Safety Management System for each class 3R, 3B, or 4 laser.

Class 4

Class 4 lasers are the most hazardous lasers. Exposure to the primary beam, specular reflections, and diffuse reflections are hazardous to the skin and eyes. In addition, class 4 lasers can ignite flammable targets, create hazardous airborne contaminants and usually contain a potentially lethal high voltage supply. The power output for CW lasers operating in all wavelength ranges is greater than 500 mW. All pulsed lasers operating in the ocular focus region (400 nm to 1,400 nm) should be considered Class 4.

Class 3B

Class 3B lasers can produce accidental injuries to the eye from viewing the direct beam or a specularly reflected beam. Class 3B laser power outputs are between 5 - 500 mW for CW lasers. Except for higher power Class 3B lasers, this class will not produce a hazardous diffuse reflection unless viewed through an optical instrument.

Class 3R

Visible continuous lasers in Class 3R are limited to 5 mW. For other wavelengths and for pulsed lasers, other limits apply.

Class 3a

Class 3a lasers cannot damage the eye within the duration of the blink or aversion response. However, injury is possible if the beam is viewed through binoculars or similar optical devices, or by staring at the direct beam. Power outputs for Continuous Wave (CW) lasers operating in the visible range are between 1 - 5 mW.

Class 2

Class 2 lasers are incapable of causing eye injury the duration of the blink, or aversion response (0.25 sec). Although these lasers cannot cause eye injury under normal circumstances, they can produce injury if viewed directly for extended periods of time. Class 2 lasers only operate in the visible range (400 - 700 nm) and have power outputs between 0.4 µW and 1 mW for CW lasers. The majority of Class 2 lasers are helium-neon devices.

Class 1

Class 1 laser devices cannot produce damaging radiation levels to the eye even if viewed accidentally. Prolonged staring at the laser beam however, should be avoided as a matter of good Industrial Hygiene practice. This class has a power output less than 0.4 µW for Continuous Wave (CW) lasers operating in the visible range. A completely enclosed laser is classified as a Class I laser if emissions from the enclosure cannot exceed limits for a Class 1 laser. If the enclosure is removed, e.g. during repair, control measures for the class of laser contained within are required.

Unknown Class

Laser classification can be determined by measuring the output irradiance or radiant exposure using instruments traceable to the National Bureau of Standards. These measurements should only be performed by qualified personnel. The laser class can also be determined from calculations. For CW lasers, the wavelength and average power output must be known. Classification of pulsed lasers requires the following information: wavelength, total energy per pulse (or peak power), pulse duration, pulse repetition frequency (PRF), and emergent beam radiant exposure. Also, laser source radiance and maximum viewing angle subtended by the laser must be known for extended-source lasers, such as injection laser diodes. Detailed information on classifying lasers may be found in the ANSI Z136.1-2014.