laser goggles
jmmygoggle is afraid of lasers
Laser eye injuries can happen in a multitude of ways but always involve a laser beam inadvertently diverted into the eye. For example, a researcher in a physical chemistry laboratory is aligning the output beam of a neodymium-doped yttrium- aluminum-garnet (Nd:YAG) laser-pumped optical parametric oscillator (OPO) to direct it into a gas cell to study photodissociation parameters for a particular molecule. Leaning over a beam director, he glances down over an upward, secondary beam and approximately 80 µJ enters his left eye. The impact produces a microscopic hole in his retina. A small hemorrhage is produced over his central vision, and he sees only red in his left eye. Within an hour he is rushed to an eye clinic where an ophthalmologist tells him he has only 20/400 vision.SourceIn another example, a physics graduate student attempts to realign the internal optics in a Q-switched Nd:YAG laser system—a procedure normally performed by a service representative, but one that the student has witnessed several times before. A “weak” secondary beam reflected upward from a Brewster window enters the student’s eye and produces a similar hemorrhagic retinal with a severe loss of vision.
Though such accidents occur each year, often they do not receive publicity because of administrative reasons or litigation.5,6 Because almost all open-beam lasers pose a severe hazard to the eyes, scientists and engineers must wear eye protection or observe other safety measures. However, laser users often make excuses for not wearing eye protection. All too common, the familiar phrases “I know where the beams are,” “I don’t place my eye near a beam,” and “Safety goggles are uncomfortable” are heard in the lab. Unfortunately, in most laser-related accidents, eye protectors were available but not worn.
Injuries do not always happen when eye protectors are not worn because the probability that a small beam will intersect the 3 to 5 mm pupil of a person’s eye is small. For the people who don’t wear goggles, the risk of injury appears to be acceptably low or they would choose protection. But consider the following scenario: If these same individuals were given an air rifle loaded with 100 BBs, placed in a stainless-steel-lined cubical room 4 m on a side, and told to fire all of the BBs in a random direction, how many would be willing to do this without heavy clothing and eye protectors? Not many—the risk of firing without protection would seem too high. Yet the probability of being hit with a BB in that scenario is about the same as that of sustaining a laser eye injury when not wearing goggles.
Comfortable laser goggles exist. The common complaint that one cannot see the beam to align it is readily solved; for example, the image converters and various fluorescent cards used to align IR beams can be used for visible lasers as well.
Nonvisible beams can pose subtle hazards. Our instinctive aversion to bright lights that can trigger a reaction to visible beams does not come into play for IR and UV beams—users may not know to look away from damaging beams until it is too late. The black anodized surface used in many lab setups can be a good reflector in the IR spectral region, which sets the stage for damage by a reflected beam.
18 June 2003, 16:03 ::
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i was unknowingly in a room where they were shooting xrays of horses and was the only sorry sucker without a lead flack jacket to cover my intestines or drape over my stones….
i’m talkin rads baby, rads.
— rmckaggis 2003-06-27 06:30 #