Posted 12 January 2013 - 04:08 PM
Posted 12 January 2013 - 05:48 PM
Posted 12 January 2013 - 08:44 PM
The center of the mirror is in the shadow of the diagonal, so it doesn't matter.
Seems like it because the right one has 6 clearly defined spots. I'm assuming that the big red donut hole in the center of the right one is not good.
Posted 13 January 2013 - 12:16 AM
Posted 13 January 2013 - 03:28 PM
Taking ferric stainless as that has a low coifficient of expansion it's 10um/m/C. Aluminium is a bit more than twice this. If the support bars are 50mm long they change at 1/20 of that or 500nm / C so if there is a temperature difference of 1/250 C there is 2nm difference in the support height and it's hard to imagine them all being at the same temperature to that sort of accuracy and plop goes the mirror. I have also heard of people testing mirrors mounted like this and running into problems even when they are lying flat which sort of suggests the problems are more than 2nm. I also feel it would take a pretty thick backing plate to limit deflection to that sort of extent so also just how thick does that have to be?
Posted 13 January 2013 - 09:29 PM
Posted 13 January 2013 - 10:30 PM
Posted 14 January 2013 - 02:04 PM
Mirror can slide loosely though, on ball bearings.
You build the cell on the back of the mirror, use about 2mm thickness of silicone.