Quote:
Originally Posted by g__day
You can use it to look straight up - shame you can just spin it - freeze it - and use it!
Better still - from myth busters trying to make Archimedes mirror to burn the Persian fleet. Jamie streched mirro shiny plastic foil over a round 44 gallon drum and vaccuum pumped out alot of air. The resulting shape in the foil is supposed to be perfectly parabolic!
What an easy way of producing a very large, very light, very parabolic mirror - where a change in vaccum achieved would change the focalpoint!
Suprised no one has tried this yet!
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This thing is patented a long time ago :-( I discovered this when I tried it years back, and it sort worked.... My problem then was I could not get hold of aluminized mylar foil).
BTW, this principle (vacuum on one side of the glass plate) is used in a process to grind the Schmidt plate for large appertures (this was published in 80's in Sky&Telescope).
However, the variation of this method may work in space - like inflating a large transparent sphere with low pressure gas.. the sphere must be partly aluminized at one side, of course....