[Laser] Big adaptive optics

[Terry Morris W5TDM]

Astrovideo is not adaptive optics. It is just an image accumulator, just 
collects a lot of images and then throws away the bad ones, and adds the 
good ones. It does nothing to correct the wavefront in real time. For laser 
communications it would be of no use. Adaptive optics has some active 
optical element that moves to correct out of phase wavefronts. There are 
some adaptive optics avaliable for the amateur astronomer. Made by Santa 
Barbara Instrument group, called the AO-8 and AO-L. The AO-8 is set for a 
target price of under $600, but that doesn't include the CCD camera which is 
not cheap. The CCD camera has two CCD sensors, one big for imaging, and a 
small one for tracking. The adaptive optics use the small CCD detector to 
detect the wavefront and drive the feedback loop to correct the out of phase 
image.


>From: "Laser @ KatHouse1.com" <laser at kathouse1.com>
>Reply-To: Free Space LASER Communications <laser at mailman.qth.net>
>To: "Free Space LASER Communications" <laser at mailman.qth.net>
>Subject: Re: [Laser] Big adaptive optics
>Date: Fri, 21 Sep 2007 15:35:15 -0400
>
>This has also been available to the backyard astronomer for quite a few
>years using a standard video camera and a program called Astrovideo.  I've
>been using the program for quite a few years.  The results are nothing 
>short
>of spectacular not only for eliminating atmospheric distortion but also
>because it has the ability to stack images and literally pull the image up
>out of the noise.  I can see objects using this setup that I can't even
>begin to see using my eyes and any eyepiece that I own  I can image deep
>space objects from my light polluted front yard by lining the camera up on
>the known starfield around the desired object then let Astrovideo do it's
>magic.  Sometimes in as little as 10 to 15 seconds the desired object will
>start to appear out of the noise.  The program has many different modes
>depending on whether you are trying to enhance signal to noise, eliminate
>atmospheric distortion or both.  The program has both automatic and manual
>modes for stacking images.
>
>http://www.coaa.co.uk/astrovideo.htm
>
>=====
>
>----- Original Message -----
>From: "J Forster" <jfor at quik.com>
>To: "Free Space LASER Communications" <laser at mailman.qth.net>
>Sent: Wednesday, September 19, 2007 1:52 PM
>Subject: Re: [Laser] Big adaptive optics
>
>
> > This idea has been around on that telescope since at least the 1960s. It
>was first done with movie film as I remember.
> >
> > -John
> >
> >
> >
> > James Whitfield wrote:
> >
> > > I just read an article that was forwarded to me by members of the
>astronomy club about a technique for using adaptive optics on the 200 inch
>Hale telescope on Mount Palomar.  The concept is that the dynamics of the
>atmosphere will cause for brief times on small areas of the image formed by
>the telescope to have less blurring than the image as a whole or if the
>pixels are integrated for longer times.  The use of a "fast" ( all of 20
>frames per second ) camera is used to capture a succession of images which
>are then searched for these "lucky" patches which are then combined.  I
>thought it was interesting reading.  (  If you are curious, try searching
>for "Palomar" and "Lucky Camera". )
> > >
> > > There might be something that can be adapted to light communication
>experiments at our level.  Maybe use the peak output from an array of 16
>light sensors.  Maybe integrate the light comming to a sensor during a 
>frame
>then reseting it.  Maybe it is just thinking about the optical system for 
>an
>image telescope as it contrasts to a communications instrument ( What does
>sharp focus/blurred image mean for a single pixel camera?  Or light
>modulated with a data stream? ).
> > >
> > > Does it spark any ideas for any of you?
> > >
> > > James
> > >  n5gui
> > >
> >
> > _______________________________________________
> > Laser mailing list
> > Laser at mailman.qth.net
> > http://mailman.qth.net/mailman/listinfo/laser
>
>
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