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On Monday, September 18, 2023 at 12:08:54 AM UTC-6, RichA wrote:
> Changes to Beryllium (what the Webb has) with temperature are probably
> more than borosilicate glass. But the Webb has its heat shield.
Yes, but:
- The Webb space telescope is kept at a constant, and very low, temperature
to avoid it glowing at the very wavelengths it is to observe;
- It has a segmented mirror, not a monolithic one; and
- Beryllium, being a metal, conducts heat more effectively than borosilicate
glass, so temperatures within it are more uniform.
So there are multiple reasons why it would be less in need of adaptive optics -
which, in a sense, it has, since the individual mirrors were
brought into position
to make it work - than a telescope with one large glass mirror.
John Savard
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