Windows thickness

[ALAIN MAURY]

Dear CCD-world :

Am trying to figure out what thickness should a given CCD dewar
window be. Does somebody know of a nice formula which would
give a recommended thickness versus diameter.
I assume not. Very likely it should be possible to derive
how much a window will bow when differential pressure is applied,
and take a "security factor" from there... and multiply again
by 2.

Otherwise, what are the experimental values of "working cameras"
( i.e. without pieces of glass of a once upon a time too thin
camera window gone through the CCD ) for different diameters.
The value I am interested in would be for a 15 micron 4K, i.e.
100 mm diameter.

While you are at it, eventhough I am going to buy a silica lens
do anybody has inputs on what kind of glass or silica should
be or shouldn't be bought. I know BK7 is bad since radioactive,
but positive or negative info on any other material should be
interesting.

Thanks for any info.
Alain