For the laser safety professional, laser-protective eyewear is one's last line of defense, but most users should consider it their first line of defense. The purpose of laser-protective eyewear is to attenuate any laser radiation reaching one's eye to a level below the MPE, meaning to an exposure level that will not cause injury. Many elements go into the selection of the correct pair of eyewear. The more wavelengths one needs protection from, the greater the challenge of finding the right pair.
Users should note that in reality, beam containment will do more for a laser user than laser-protective eyewear. If you can eliminate the possibility of eye damage by enclosing the laser beam path such that no radiation exposure to the eye is possible, then do so.
Laser-protective eyewear comes in two types-full-attenuation and alignment eyewear. Full attenuation means that if the filter is struck, no level of radiation above the MPE will penetrate to the eye; therefore, when wearing the laser eyewear for the wavelength the filter is designed to filter, one will not be able to see if the termination point of the beam (or inadvertent intrabeam exposure) is feasible. Depending on the filter, secondary fluorescence may be visible, such as when the beam hits an IR-sensor card. Conversely, alignment eyewear allows an individual to see some of the termination point of the beam for various purposes, such as beam collimation, laser-beam-path alignment, etc.
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