Unfortunately the limitation of laser pointers to <5mW makes them useless for astronomy much of the time. A 1mW laser isn't worth owning as an astro-pointer. The regulations obviously are aimed at classroom and indoor lecture use, where the dot itself is used as a highlighter, not the beam. Low-powered lasers excell at this task, but they fail as star-pointers. Used astronomically, many times a 5mW laser beam must be viewed close to it's axis to be seen at all, especially under less-than-ideal sky conditions including moderate light pollution. That makes them useless for large groups (star parties), as Seth Jarvis and others on this list can attest. Not everyone can stand right behind the person with the pointer. I would hope that *everyone* using lasers as instructional tools would use them safely- not just those who opt for a higher-powered unit that actually works well as a star-pointer. Even a $2 keychain red laser can cause eye damage. In the state of Utah, as I've posted here before, it is illegal to aim a laser at a person, vehicle (that includes aircraft), or animal, regardless of power output or wavelength (color). FWIW, the laser mounted on the 32" scope at SPOC is rated at 10mW and is just bright enough to be seen under most conditions. I bought that one on behalf of the club after disappointment with several lasers of ~5mW output. Counterintuitively, under the darkest, most transparent skies, even the low-power units aren't very visible. To see the beam itself, you need particulates suspended in the air for the beam to illuminate. Excellent transparency just means you need a higher powered unit in order for the beam to be seen. Strictly on the criteria of visibility and useability, I would not not recommend a laser intended for use as a star-pointer to be rated at less than 10mW, regardless of low cost. Of course I don't advise anyone to break the law. I'm just stating an opinion as to useability in our application vs. laser output. Finally, know that just because the label on the laser states 5mW, it could in fact be much brighter- or dimmer. There is a large spread of output among diodes of the same manufacturing batch. Many are higher, many are lower. The 5mW rating is an average for the diode design. My 20mW laser (bench-tested) uses the same diode as some 5mW units yet puts out ~20.4mW. This explains why two identical lasers can often display different brightness to the eye. So while it's purchase was legal, it's actual output is higher than the law allows for. (Mine was purchased as a "best of the batch" by a seller who tests each unit individually. Few vendors do on the lower-powered lasers these days.) Good luck on your laser decision. Caveat emptor, and be safe no matter how bright or dim your laser is. On Wed, Jan 23, 2013 at 10:13 PM, Ivo Stutznegger <ics_ute@yahoo.com> wrote:
Laser products promoted for pointing and demonstration purposes are limited to hazard Class IIIa by FDA regulation. This means that pointers are limited to 5 milliwatts output power in the visible wavelength range from 400 to 710 nanometers. (Common DPSS green lasers are 532 nanometers). European and international (IEC) standards for laser classification were revised in 2001 eliminating the Class 3a designation and basically calling for laser pointer devices to be in the Class 2M or lower designation limiting output to 1 mW. The reason for these standards are safety. Lasers that emit between 5mW and 500mW output power are in Class IIIb (or IEC Class 3B). Class IIIb lasers cannot legally be promoted as laser pointers or demonstration laser products in the US. Radiation in this class is considered very likely to be dangerous. As the FDA puts it,"Irresponsible use of more powerful laser pointers poses a significant risk of injury to the people exposed. Persons who misuse or irresponsibly use lasers are open to personal liability and prosecution." My advice to anyone that chooses to own and use a handheld laser of >5 milliwatt output is to make sure you are extremely careful or you are putting yourself and those around you at risk of eye damage. I would also note to those interested in ordering powerful laser pointers from Chinese suppliers that the FDA considers Class IIIb hand-held lasers too dangerous for use as pointers or amusement articles and subject to detention and seizure by the U.S. Customs and Border Protection when imported. Additional information can be found at the FDAs website at: http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm166649.htm