[Atmob-discuss] Vision Safety and Laser Pointer Use

[George Roberts]

A little clarification:
"150mw can be seen a mile away".

What this usually means is if you point the laser pointer straight up, then someone a mile away can visually see the beam pointing upwards through the air.

I have found that 55mw can be seen up to about 300 feet away.  If it was arizona desert dark, and one was 40 minute dark adapted and an experienced observer I can believe it *might* be possible to see 150mw laser beam pointing straight up from a mile away.

A 5mw green laser can easily be seen much more than a mile away if it is pointed right at you.

The lasers used in outdoor laser shows and in planetarium laser shows are much more powerful than a measly 150mw.

- George 

----- Original Message ----- 
  From: Bob Napier 
  To: atmob-discuss at atmob.org 
  Sent: Wednesday, April 22, 2009 4:25 PM
  Subject: [Atmob-discuss] Vision Safety and Laser Pointer Use


  Recently there has been a proliferation in the use of green laser pointers at star parties.
  Some of these pointers advertised for amateur astronomy use are rated at 150 mw power.
  When looking at some of the demonstration videos posted on various vendors' web sites, they show igniting paper, cutting through thin plastic containers, heating matches to ignition, bursting a series of balloons at up to 20 feet, etc.  Some also say that the laser's beam is visible for up to a mile high, which is well within the reach of commercial airliners near airport landing patterns.
     
  At amateur events such as star parties, what would happen to a person's vision if such laser were accidentally aimed into their eyes, whether directly, or indirectly by reflecting off a bright piece of metal (nail heads, screw heads, auto chrome or mirrors, etc.) or some bright piece of a telescope assembly?  Also, I have read about some federal agency investigating amateur's lasers striking airplanes, but do not know what the outcomes of such investigations were.
   
  Below is a statement about the upcoming RTMC in CA:


  "Lasers and Laser Pointers
  The use of lasers, except for collimation or as a pointer by a speaker in the meeting hall or the Beginner’s Corner sky orientation, is STRICTLY PROHIBITED. Thank you for your cooperation."



  Are there any policies in effect with regard to the use of laser pointers (especially vision safety aspects of 150 mw power ranges), at ATMoB, Stellafane, or any other astronomy clubs or groups during star parties at schools, for scouts, etc., and at members observing sites?  For astrophotographers', are there concerns even at 5 - 10 mw power levels?  At what point do laser pointers' power rating become a vision safety issue (or hazard and legal liability) and override their usefulness for pointing out objects in the sky?



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