ATM Re Active optics

[GregJ888@aol.com]

- -If you're at all serious about this, get your hands on a copy of JOSA
 March 1977. It's a special-topic issue on adaptive optics. Good Stuff.

** SPIE also has some good information.  I have been saving articles for 
several years and may be able to give you a reference if you have specific 
questions.   Dr. Rodder also has a good book out on the subject.

- -I'd be inclined to try photomultiplier tubes ... 

** The "big guys" use CCDs (thinned, Back illuminated, multiple readout) or 
APDs in photon counting mode.  I think you will find PMTs to noisy for 
anything beyond tip/tilt with a very bright guide star unless you photon 
count.  It also takes 3 sensors per element unless you use curvature sensing 
(per Rodder) but then the sensor is time sliced.  For my system it would take 
12 PMTs and placement would be a real challenge.  The APDs are $4k each, the 
cheapest CCD camera made for the application is about $35k


- -The primary headache, from what I can see, is the deformable mirror,

** Can be, but the "Semi-pasive Bimorph" was pretty easy.  I've tested it 
against a flat and think it is well within a 1/2 wave edge to edge but have 
not done anything further.  One of the engineers at the Keck offered to test 
it for me but I haven't pursued it.  I hope to go over next summer, maybe 
I'll ask then.  You also need high voltage op-amps but thay too are available 
($35 each).

I saw, well actually touched, the laser guide star system while I as at the 
Keck lab.  IMHO you can forget about having a laser guide star until the AO 
system is working with a natural star....

Greg Jones