Michael, I have no way of measuring wavelength or bandwidth at present, but I'm betting that atmospheric turbulence would probably play a larger role in beam divergance over distance, don't you think?. Every distant light I saw, even in the eyepiece of the aiming telescope, was twinkling madly. Even the most coherent, narrowband wavefront would be tortured passing through that soup.

From: Michael Carnes <MichaelCarnes@earthlink.net>

Chuck do any of your lasers list bandwidth as a specification? While the nature of the laser means that emitted light will have a narrow bandwidth, I can't help but think that material purity would have a big impact on coherence of that light. That it turn would have a big effect on the beam's ability to hold together over distance.

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