On 27/05/2021 20:04, John Rumm wrote:
On 27/05/2021 19:39, nightjar wrote:
....
Clear cast acrylic sheet is what I would try - inherently UV resistant
and with up to 92% visible light transmission - highest when the light
strikes perpendicular to the surface. I can't find values for its
transmission in the IR range though.

I think, go with whatever is to hand and re-calibrate the thresholds
expected in the software to allow for the chosen window material.

You do, however, need to be sure that, whatever you use, is not degraded
by UV. That would lead to a progressive loss of transmission over time.
That is why I like acrylic sheet - it is completely UV resistant without
the need for any coating.

It is also likely to be what I have to hand :-)

--
Colin Bignell