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Vacuum mirrors
I went to uni in Scotland with Peter, and have copies of all his reseach notes on the mylar mirrors.
In the early 90's I made two 16" frames and a vacuum system to trial the concept. The issues were lack of surface accuracy; the edge wrinkles distorted things well into the centre. I tried pre-streatching before pulling the vacuum; modifying the edge radii and clamp rings etc etc. I could not get any worthwhile imaging results. The ronchi testing showed the surface was all over the place.
I then tried with a 2mm thick sheet of plate glass and managed from memory, to pull it to f9; it sat on an O ring edge seal... looked very promising.
I'm overseas at the moment so don't have access to my notes etc.
It's certainly a VERY interesting concept, but one which doesn't seem to work with optical accuracy.
(BTW I also tried some samples with slumped 3mm glass disks.... you can get the radius but they still need polishing...not an easy feat with such a thin mirror)
Ken
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