Chris L Peterson wrote:
On Fri, 09 Jul 2004 05:25:58 GMT, Eric wrote:

Use a high contrast region on the surface of the moon. Just like they do
with the solar telescopes that use AO. Think Registax... use the same
math to point the tip/tilt mirror. Sure, maybe you get 30" patch if
you're lucky, but we're talking about high resolution. You have to
oversample the telescope to make it worth while.

I was thinking more in terms of higher order corrections, which are difficult to
do with anything but a point source reference. But I agree, at very high
magnifications you could get some benefit from tip/tilt using simple feature
correlation for control.

If you can build a Shack-Hartman mask, then you get multiple images of
the tracking target. Then use the correlation to determine the shifts of
each subimage. Then you can reconstruct the higher orders. If you're
imaging the Moon or the Sun, you have lots of light. You need
field-stops to keep the images from overlaping on the sensor. It takes
some real computing power, but I expect you'll be limited by the readout
rate of the camera.

Eric.