Laser Safety Manual

Laser Safety Manual 40 Glossary Absorption Transformation of radiant energy to a different form of energy by interaction with matter. Beam Acollection of light/photonic rays characterized by direction, diameter (or dimensions), and divergence (or convergence). Blink Reflex or Aversion Response The involuntary closure of the eyelid or movement of the head to avoid exposure to a noxious stimulant or bright light. It often occurs within 0.25 seconds, which includes the blink reflex time. Coherent A beam of light characterized by a fixed-phase relationship (spatial coherence) or single wavelength i.e., monochromatic (temporal coherence) Continuous Wave (CW) The output of a laser operated in a continuous rather than a pulsed mode. For purposes of safety evaluation, a laser that is operated with a continuous output for a period of > 0.25 seconds is regarded as a CW laser. Controlled Area (laser) An area where the occupancy and activity of those within is subject to control and supervision for the purpose of protection from laser radiation hazards. Diffuse Reflection Change of spatial distribution of a beam of radiation when it is reflected in many directions by a surface or by a medium. Enclosure A barrier used to enclose the laser beam. Energy The capacity for doing work. Energy content is commonly used to characterize the output from pulsed lasers and is generally expressed in Joules (J). Environmental Health and Safety (EH&S) The department at Iowa State University that has the authority to evaluate, monitor and enforce the control of lasers and laser systems for all laser users. Environment, Safety, Health and Assurance (ESH) The department at Ames Laboratory that has the authority to monitor and enforce the control of lasers, laser systems and laser hazards for all laser users within Department of Education (DOE)- owned buildings or on DOE-funded projects. Fail-Safe Interlock An interlock where the failure of a single mechanical or electrical component of the interlock will cause the system to go into or remain in a safe mode. Housing The protective enclosure that contains a laser. In the case of Class 3B and Class 4 lasers, this case