Metal reflects far-IR, so anything metal used as a heat mirror will work, so longas its a clean metal surface with no paint, anodizing or other surface layer.
No lenses or anything
this is my plan for a long distance break beam sensor.
MLX90614 infrared sensor that I want to use on my robot to detect humans and animals at range by comparing the ambient temperature and the temperature of object in front of the sensor
Is that all that is needed here? Just a metal tube? No lenses or anything?
But how can I determine what kind of lens I need to buy to have the range and field of view that I need?
Basically you can't. I would be surprised if such a thing exists for you to buy anyway.What has this to do with Audio? Why is it in the Audio section!?A lens for passive IR for use in thermal imaging is very heavy and very expensive in the order of $300
mistakenly put this topic in the wrong section, and I don't know how to fix it
Basically you can't. I would be surprised if such a thing exists for you to buy anyway.