Books on amateur telescope making emphasize that machining lenses and
mirrors is prone to produce astigmatism, whereas hand grinding lenses
and mirrors tends to randomize errors and thereby avoid stigmatism.
On the other hand, I haven't heard any complaints about astigmatism in
commercially ground lenses and mirrors, and I doubt very much that they
are ground by hand.

So, what I would like to know is this: what are the machines and processes
used by commercial manufacturers of telescopes and what book explains them
in detail?

Ignorantly,
Allan Adler


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* Disclaimer: I am a guest and *not* a member of the MIT Artificial *
* Intelligence Lab. My actions and comments do not reflect *
* in any way on MIT. Moreover, I am nowhere near the Boston *
* metropolitan area. *
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