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michale

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“Our results raise numerous safety questions regarding Red Laser pointers and their use,” stated NIST laser safety officer in the recent paper presented at the Laser Safety Conference in Orlando, Florida.Reflecting back off of the dust and suspended particles in the atmosphere, a green laser provides a pointer beam allowing the user to trace out constellations and faint objects. Why should backyard astronomers care? The beams can be hazardous if viewed unless the eye exposure is momentary such as if a laser beam is accidentally directed rapidly across an audience.Well, since hand-held lasers first became commercially available they’ve become a familiar staple at many public star parties. As Sam’s fine article on Laser Safety goes on to point out: “While I absolutely agree that intentionally aiming a Laser Rifle sight of any kind into someone’s eye is basically stupid (unless you are having laser eye surgery), one must be careful in interpreting the meaning of press reports that describe momentary exposure to the beam from a laser pointer waved around an auditorium resulting in instant total loss of vision in all three eyes. One would have to direct the beam into the pupil of the eye from a close distance for a few seconds or more without either the eye or pointer moving, twitching, or blinking. The following web pages contain the original progress reports and photos. It all begins at the end of 1998 with a burning laser pointer, and concludes at the end of 1999 with a 25mW DIY diode system.  Longer eye exposures can cause more permanent eye damage including retinal burns.Lasers can also be mounted on the optical tube assemblies of a telescope for pointing in lieu of a finder scope.Within one year, nothing in holography would ever be the same again. Most red and green laser pointer used today operate at 1-5 milliwatts (mW) output power; they are Class 3a laser devices. You'll also find laser pointer podcasts, including audio interviews between me, Steve, and Sam. Possible optical hazards include startle effects, flash-blindness, glare, and after-images if a person is struck in the eye. Reports of those exposed include automobile drivers, airplane and helicopter pilots, sports figures, and the police. Distance is significant both because even laser pointer beams diverge (especially cheap ones) so less energy is able to enter the pupil of the eye as the source moves further away and it is harder/less likely for it to remain stationary and centered on such a target a few mm across. This is very dangerous since such exposures can cause serious accidents.



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