Commercially purchased lasers are classified either by the US Performance Standard (21 CFR 1040) of the Center for Devices and Radiological Health (CDRH) or the International Code (IEC 60825-1). Classification is based on the level of hazard of the laser beam during normal operation and includes factors such as wavelength, power output, accessible emission level, and emission duration. Commercially purchased lasers bear a sticker indicating the laser class. The following classes are defined:
Class 1 laser systems do not emit hazardous radiation under normal operating conditions. The laser is either of low power or the class 1 laser systems incorporates an “embedded” higher-power laser, which can be accessed only if safety interlocks are defeated or bypassed during servicing. In this case, the system temporarily reverts to the original laser classification.
A class 1M laser system has an expanded beam and is only hazardous when viewed through magnifying optics. M stands for magnification.
Class 2 laser systems are limited to the visible portion of the spectrum (400-700 nm) and to an output of 1 mW for continuous wave lasers. The natural aversion reaction to bright visible light (0.25s) is expected to protect the eyes from damage. A class 2M laser has an expanded beam and it can have a higher output. It is potentially hazardous if viewed through magnifying optics.
A class 3R laser system is potentially hazardous under some direct and specular (mirror-like) reflection viewing conditions if the eye is relaxed (focused at infinity). The natural aversion reflex is NOT adequate protection but the probability of an injury is small. The output is limited to 5 mW.
A class 3b laser system is more powerful than a 3R and is NOT safe for direct viewing or viewing of specular reflections. The output is limited to 0.5 W for continuous wave lasers.
A class 4 laser system has an output of more than 0.5 W (continuous wave). It is damaging to the eye and skin from the direct beam and diffuse reflections (scattering), and a potential fire hazard. The beam can also generate airborne contaminants and hazardous plasma radiation.
Lasers that have been built or modified at the University of Illinois need to be classified and registered with IEMA through DRS. Classification can be done according to ANSI Z136.1 which is very similar to the CDRH and IEC classifications.
The following two tables are taken from ANSI Z136.1 and were compiled to aid in the classification of a laser system. Ask DRS for assistance.
Continuous Wave (CW) Point Source Lasers
Wavelength (nm) | Laser type | Wavelength (nm) | Class 1a (W) | Class 2 (W) | Class 3 b (W) | Class 4 (W) |
Ultraviolet | Nd:YAG (Quadrupled) | 266 | <9.6 x 10-9 for 8 hours | None | >Class 1 but <0.5 | >0.5 |
Argon | 275 | |||||
Ultraviolet | He-Cd | 325 | <3.2 x 10-6 | None | >Class 1 but <0.5 | >0.5 |
Argon | 351, 363, 350.7 | |||||
Krypton | 356.4 | |||||
Visible | He-Cd | 441.6 only | <4 x 10-5 | > Class 1 but <1 x 10-3 | > Class 2 but <0.5 | >0.5 |
Argon (visible) | 457 | <5 x 10-5 | ||||
476 | <1 x 10-4 | |||||
488 | <2 x 10-4 | |||||
514 | <2.2 x 10-4 | |||||
Krypton | 530 | |||||
Nd:YAG (doubled) | 532 | |||||
He-Ne | 543 | |||||
400 - 500 | <0.4CB x 10-4 | |||||
Dye | 460 - 500 | |||||
He-Se Dye | 550 - 700 | <4 x10-4 | ||||
He-Ne | 632 | |||||
InGaAIP | 670 | |||||
Ti:Sapphire | 350 - 500 | |||||
Krypton | 647.1, 676.4 | |||||
Near Infrared | GaAlAs | 780 | <5.6 x 10-4 | None | > Class 1 but <0.5 | >0.5 |
GaAlAs | 850 | <7.7 x 10-4 | ||||
GaAs | 905 | <1.0 x 10-3 | ||||
Nd:YAG | 1064 | <1.9 x 10-3 | ||||
He-Ne | 1080 | <1.9 x 10-3 | ||||
1152 | <2.1 x 10-3 | |||||
InGaAsP | 1310 | < 0.03 | ||||
Nd:YAG | 1319 | < 0.025 | ||||
Far Infrared | InGaAsP | 1550 | <9.6 x 10-3 | |||
Holmium | 2100 | |||||
Erbium | 2940 | |||||
Hydrogen Fluoride | 2600 - 3000 | |||||
He-Ne | 3390 only | |||||
Carbon Monoxide | 5000 - 5500 | |||||
Carbon Dioxide | 1060 | |||||
Water Vapor | 118000 | <9.5 x 10-2 | ||||
Hydrogen Cyanide | 337000 | |||||
a Assumes no mechanical or electrical design incorporated into laser system to prevent exposures from lasting to Tmax = 8 hours (one workday); otherwise the Class 1 AEL could be larger than tabulated. | ||||||
b The Class 3R AEL is defined as 5 times the Class 1 AEL for invisible lasers and 5 times the Class 2 AEL for visible lasers (wavelength between 400 nm and 700 nm). | ||||||
AEL: Accessible emission limit.
Single Pulse Point Source Lasers
Wavelength (nm) | Laser type | Wavelength (nm) | Pulse Duration (s) | Class 1 (J) | Class 3b (J) | Class 4 (J) |
Ultraviolet 180 to 400 | Excimer (ArF) | 193 | 20 x 10-9 | <2.4 x 10-5 | > Class 1 but <0.125 | > 0.125 |
Excimer (KrF) | 248 | 20 x 10-9 | <2.4 x 10-5 | |||
Nd:YAG Q-switched (quadrupled) | 266 | 20 x 10-9 | <2.4 x 10-5 | |||
Excimer (XeCl) | 308 | 20 x 10-9 | <5.3 x 10-5 | |||
Nitrogen | 337 | 20 x 10-9 | <5.3 x 10-5 | |||
Excimer (XeF) | 351 | 20 x 10-9 | <5.3 x 10-5 | |||
Visible 400 to 700 | Rhodamine 6G (Dye laser) | 450 - 650 | 1 x 10-6 | <7.7 x 10-8 | > Class 1 but <0.03 | > 0.03 |
Copper vapor | 510, 578 | 2.5 x 10-9 | ||||
Nd:YAG (doubled) (Q-switched) | 532 | 20 x 10-9 | ||||
Ruby (Q-switched) | 694.3 | 20 x 10-9 | ||||
Ruby (Long pulse) | 694.3 | 1 x 10-3 | <3.9 x 10-6 | |||
Near Infrared | Ti:Sapphire | 700 - 1000 | 6 x 10-6 | <8.4 x 10-8 | ||
Alexandrite | 720 - 800 | 1 x 10-4 | <7.6 x 10-7 | > Class 1 but <0.033 | > 0.033a | |
Nd:YAG (Q-switched) | 1064 | 20 x 10-9 | <7.7 x 10-7 | > Class 1 but <0.125 | >0.125 | |
Far Infrared 1400 to 1mm | Erbium:Glass | 1540 | 10 x 10-9 | <7.9 x 10-3 | > Class 1 but <0.125 | > 0.125 |
Co:Mg-Fl | 1800 - 2500 | 80 x 10-6 | <7.9 x 10-4 | |||
Holmium | 2100 | 250 x 10-6 | <7.9 x 10-4 | |||
Hydrogen Fluoride | 2600 - 3000 | 0.4 x 10-6 | <1.1 x 10-4 | |||
Erbium:Glass | 2940 | 250 x 10-6 | <5.6 x 10-4 | |||
Carbon Dioxide | 10,600 | 100 x 10-9 | <7.9 x 10-5 | |||
Carbon Dioxide | 10,600 | 1 x 10-3 | <7.9 x 10-4 | |||
a Class 3b AEL varies from 0.033 J to 0.480 J corresponding to wavelengths that vary between 720 and 800 nm. | ||||||
Code of Federal Regulations Title 21. 21 CFR 1040.10 Laser Products
American National Standard for Safe Use of Lasers. ANSI Z136.1 - 2014, tables C1 and C2