Actually this was more of a tongue in cheek reference to the excellent talk by Dr. Gates at the last SJAA meeting at Houge. Turley was there as was Craig and Elena (hope I spelled your name right) as was Jim Van Nuland, so the Tacos were well represented.
The reason for the laser was that sometimes they simply cannot get a guide star where they need one to take their images with their AO system. So they "manufacture" their own. What they do is exploit the fact that there's a layer of sodium waaaaay up there at the edge of the atmosphere by irradiating it with a laser at exactly the right wavelength to cause it to become excited so as to emit secondary radiation. Since they can make this star appear where ever they want, and since it is just above the majority of the atmosphere, the disturbance of the target light going through the atmosphere equally affects the light from the artifical guidestar. They use that light for guiding and for controlling their Adaptive Optics system. It is really cool how it all works. Turns out that they have to have that AO guidestar very close to the object d'interest: the air disturbance cells are small so they want to make sure they are using the correct cells for compensation.
Imagine being able to have near-perfect seeing any time the sky is clear. That's what they get. That would be awesome for visual work too.
I've only attended two of the lectures at the SJAA, and they have both been very very interesting. This one was especially so, being keenly interested in the topic. If Dr. Gates is reading this, please accept my congratulations for an excellent talk and my thanks for giving it.
----- Original Message -----
From: RichardN22@No-Spam
To: sf-bay-tac@No-Spam
Sent: Friday, January 30, 2004 4:15 PM
Subject: Re: [TAC] Green Laser Ptr as a Finder -- NOT
In a message dated 1/30/2004 4:14:25 PM Pacific Standard Time, rdcrisp@No-Spam writes:
If we could get them to operate at the wavelength of Sodium, and boost the power to 250Watts or so, we could use them for guidestars: just like the AO folks at Lick do. Of course you gotta clear each use/target with NORAD, the FAA and so on. But imagine having your very own guidestar that you can use to operate real industrial strength adaptive optics. Wow majorly cool! And this stuff isn't just for imaging: there's no reason in principle that you couldn't do visual with it.
rdc
No thanks, I prefer the real stars.
Richard