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This is an Email that I received describing visual EME at 532 nm !

To: "John K3PGP"

Date: Tue, 9 Sep 1997 23:08:15 -0500

Subject: Visual EME !

(I used to be able to sparkle off the new moon with my YAG at full power and full convergence.  It takes some doing but you can see the sparkle from the sea of tranquillity with the naked eye off the corner cube reflector, aka: retroreflector left there in 1969 by the astronauts....)

: Interesting.What did you collimate the beam with?: What was the lasers' power.

Galilean beam expander.  80mm on the output objective (high precision achromat, not planoconvex) and a 5mm doubleconcave on the input. All lenses were AR coated and cooled (otherwise they'd ablate/vaporize). Divergence was very low with this beam expander.  :)

Lasers power (input) was greater than 10 joules pulse, at a 15Hz rep rate, 532nm wavelength.  Twinkle was seen with a Celestron telescope and my eyeball.  Not very scientific but fun.  If the moon is new, you can see the twinkle of green with the naked eye, full moon requires a telescope to isolate the scant few photons that make it all the way back.

(I use this YAG for advertising new Lasertag gamesites.  It runs from Des Moines Iowa all the time, and pilots tell me the beam is visible as far way as Denver from Des Moines, and Chicago from Des Moines.  These are the only reports I've received, from the regular routes.  I've only gotten friendly with the local pilots, never get to know the ones when I'm running remote. It's been in Berkeley, Sacramento, Ft. Wayne, Evansville, and will be running next week in Cancun Mexico.

Now before anyone gets upset, I have a CDRH variance to operate this yag in an outdoor environment WITHOUT a beam block or termination point, and have FAA authorization and air clearance as well.  100% legal and by the book!

Please note I turn the power way down for beam shows, the power level to shoot the moon was a special case and I had TWO plane spotters for safety. The power output is 0.9725mw cm^2 at 750 feet which translates into a fiber launch power of about 30 watts, not over 35 watts, so it's safe..........)


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