I have a PIR for sensing people in our garden. I want to have the PIR located behind glass or plastic.
If the PIR is behind glass then the glass blocks the heat which triggers it. I image a clear plastic sheet would also block heat.
Is there some special plastic (like that used in the PIR's lens) which can transmit heat?
Thin polythene. It's what the lens is made of.
I have a mini-IR camera and IR LEDs in a bluetit nestbox and use the bottom of a plastic milk carton (the 4 pint/2 litre sort) to protect the LEDs. It works fine - no obvious loss of IR. Of course PIRs might work on a different part of the IR spectrum.
-- LSR
Vastly different. IIRC, it's 700nm for IR LEDs, and about 20-40 times that for PIR.
However, the polythene from such a bottle may be suitable for both.
Have something to add? Share your thoughts — no account required.
Ask the community — no account required