Radiation Safety
Glossary of Laser Terminology
accessible emission limit (AEL)
maximum accessible emission level which is permissible in the appropriate class of laser
accessible radiation
laser radiation that can expose human eye or skin in normal usage
aperture
the opening through which laser radiation can pass
average power
total energy of an exposure divided by the duration of the exposure
aversion response
action, such as closing of the eye or movement of the head, to avoid exposure to laser light
beam diameter
diameter of the laser beam where to power per unit area of the beam is 1/e timmes that of the peak power per unit area
continuous wave (CW) laser
a laser which with a continuous output that is greater than or equal to 0.25 s
infrared radiation
electromagnetic radiation of wavelength from 700 nm to 1mm
irradiance
power per unit area, expressed in watts per square centimeter
laser
acronym for Light Amplification by Stimulated Emission of Radiation
laser safety officer
individual who has the authority to monitor and enforce the control of lasers
maximum permissible exposure (MPE)
the maximum level of laser radiation to which a human can be exposed without adverse biological effects to the eye or skin
nominal hazard zone (NHZ)
the zone inside which laser radiation that is direct, reflected, or scattered exceeds the MPE for the laser
nominal ocular hazard distance (NOHD)
distance along the axis of the direct laser beam to the human eye beyond which the MPE of the laser is not exceeded
pulsed laser
laser which delivers energy in single or multiple pulses which are less than or equal to 0.25 s in duration
radiant energy
laser energy emitted, expressed in joules (J)
radiant exposure
radiant energy per unit area, expressed in joules per square centimeter
radiant power
laser power emitted, expressed in watts (W)
repetitively pulsed laser
laser with multiple pulses with a pulse repetition frequency greater than or equal to 1 Hzspecular reflection
mirror-like reflection
ultraviolet radiation
electromagnetic radiation with wavelengths from 180-400 nm
visible radiation
electromagnetic radiation which is visible to the human eye; wavelengths from 400-700 nm
Questions?
Contact the Division of Research Safety, Radiation Safety Section (333-2755 or via e-mail) or visit our website: http://www.drs.illinois.edu/rss/.
Other Radiation Safety Fact Sheets are available from the Radiation Safety Section at our website: http://www.drs.illinois.edu/rss/factsheets/.
