Infrared.
Shiny aluminum foil.
Infrared is heat. When you feel the warmth of a space heater, you feel the effect of infrared radiation. The other uses are motion detection (infrared sensor) and night-vision (live animals have a heat signature, a blurred image, against a colder background at night). ======================
The most vital element in crime detection and criminal investigation is the human element.
Yes, there most certanly is. They seem a bit expansive, but gas leaks can be too. I will place a link or two in the comments that you can look at if you want. I can't put them here. There are a number of detection methods which can be used to detect gas leaks. These include Infrared Point, Infrared Imaging, Ultrasonic, Holographic, Semiconductor, and Electrochemical detection.
Joseph Caniou has written: 'Passive infrared detection' -- subject(s): Infrared detectors
infra-red. harmless. same as the beam from your remote control.
George Rieke has written: 'Development of far infrared detection techniques' -- subject(s): Infrared detectors
antimony
A group 5 metalloid that is quite versatile is antimony. It is often used in tractor bullets, as fireproofing material and for infrared detection.
If you want to connect it to a computer you can view the disturbances in the infrared light.
Used for error detection