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Example:EXAMPLE 1: In the U.S., lasers sold as pointers must be less than 5 mW. A typical divergence is 1 milliradian. What is the Nominal Ocular Hazard Distance? The 50/50 injury chance distance?
NOHD (Nominal Ocular Hazard Distance) in feet = (32.8 / 1) * (square root of (0.5 * 5)) = 32.8 * (square root of 2.5) = 32.8 * 1.58 = 51.9 feet ED50 distance in feet = 51.9 / 3.16 = 16.4 feet
Answer: The Nominal Ocular Hazard Distance of a 5 mW laser pointer with 1 mrad divergence is 51.9 feet. The ED50 distance means that if a person is 16.4 feet from the laser and is exposed under laboratory conditions (the laser and eye are fixed relative to each other), there is a 50/50 chance of causing a minimally detectable retinal lesion.
In short, unless the guy was sitting within 16 feet of the plane/helicopter, he has a 50% change of inducing ANY form of damage to the retina. On the other hand, could the laser pointer pose a distraction to the pilot and the pilot could make a fatal error. Sure, but a ringing cellphone might do the same.
Residents of the South Pacific island of Tanna worship an American "messiah" named John Frum who first appeared to them in the 1930s. According to a village elder quoted in a recent Smithsonian article, John promised to someday return and "he'll bring planeloads and shiploads of cargo to us from America if we pray to him. Radios, TVs, trucks, boats, watches, iceboxes, medicine, Coca-Cola and many other wonderful th