Re: ATM keck, off axis mirrors, and machining glass

[astillma@nit.AirTouch.COM (Anthony Stillman)]

> On the UCSD cable channel  yesterday, there was a video showing how
> the professionals built the Keck MMT. Each  offaxis mirror segment was
> first mechanically deformed, then polished as if it were an on axis
> mirror. When the mechanical deformation was removed, the segment would
> pop into its offaxis figure. Reminded me of the vacuum method of
> making correctors. The process of making the Keck MMT segments did not
> look like it was in the realm of  amatuer telescope making though.

Donald Clement
San Diego/Running Springs

It was a great idea, but alas it didn't work in production.  Still, they
currently use deformation to control the figure of the elements as they
sit in the telescope, or so I've been told by one who worked on the Keck.

Anthony