Question

The thermal cameras or infrared cameras are used to see in very dark places or even totally dark. I would like to know how Infrared electromagnetic waves work in these night vision cameras?

Answer 1

Infrared(IR) waves, or infrared light, are part of the electromagnetic spectrum. Our eyes cannot see these waves but some instruments can sense infrared energy—such as night-vision goggles or infrared cameras–allow us to "see" the infrared waves emitting from warm objects such as humans and animals.

Infrared Energy Detection

An infrared camera is a non-contact device that detects infrared energy (heat) and converts it into an electronic signal, which is then processed to produce a thermal image on a video monitor and perform temperature calculations. Heat sensed by an infrared camera can be very precisely quantified, or measured, allowing you to not only monitor thermal performance, but also identify and evaluate the relative severity of heat-related problems.

Working of infrared camera

An infrared camera measures the amount of infrared radiations falling on its detectors through special calibrations some thermal imaging cameras are able to measure the temperature of the object. Thermal imaging is not the same as using night vision goggles, night vision goggles amplify small amount of visible light so that object can seen at night, they only work if there is at least some light like moonlight or star light is present. While thermal imaging works by detecting the heat energy being radiated by objects in form of infrared radiations.

Glass does not transmit infrared radiations so the lenses of an infrared camera are made up of germanium. Because Ge is a good transmitter of IR radiations.

IR radiation coming from an object focused on an infrared detector, the detector sends the information to sensor electronics to process the image. The electronics translate the data coming from the detector into an image that can be viewed in the viewfinder or on a standard video monitor.

IR thermography is the art of transforming an IR image into a radiometric one which allows temperature to be read from the image.