On Jan 14, 5:21*pm, "William Sommerwerck"
wrote:
It's not a silly question.

Regular glass supposedly reflects infrared, does it not? And these devices
measure infrared, is not so?

Actually, glass reflects or absorbs infra-red based on angle and
composition and coatings (if any). Were it to reflect (all of) it, a
lens would not be very good at starting fires in by concentrating
sunlight.

Further, these guns use a laser and some sort of sensing device - so,
I am trying to determine how good it would be at sensing say... a wall
temperature a few feet inside a building through a window.

Peter Wieck
Melrose Park, PA