On 28/05/2021 12:11, John Rumm wrote:
On 28/05/2021 10:13, nightjar wrote:
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 :-)

Yup acrylic and proper glass should be fine. Polycarbonate might not be
so good in this case. Having said that it can still get dirty outside
regardless of material - so a bit of slack built into the thresholds is
not a bad idea.


A microscope cover-slip is a good source of thin flat glass.