N_Cook wrote:
Or at least translucent to visible. Hopelessly undiscriminating IR encoder &
decoder on a piece of kit but need to see the LED segment display , which
inconveniently has the IR Rx within it.
I've tried loads of normal materials like polythene,perspex, glass, mica,
silicone rubber.
I know black polythene will transmit the IR of PIR units and block visible
but there is more seperation of f there

how about a "hot mirror" photographic filter?

they're for old digital cameras that are sensitive to IR.

they appear to be some sort of dichroic filter and their color changes
depending on what angle you look at them. They look clear straight on.

Tiffen made them at some point.