A Radiometric Thermal Imager: How Does it Work?

The Functionality of a Radiometric Thermal Imager

A radiometric thermal imager uses a rotating mirror with a single, very fast response detector or a linear array of IR detectors to measure successive areas with a single stationary device.

Final Answer

A radiometric thermal imager uses a fast response detector or an array of IR detectors with a rotating mirror to measure consecutive areas. These detectors have to be cooled significantly, usually with liquid nitrogen or helium, to effectively function. Modern detectors like CCDs are more efficient, creating comprehensive 3D images.

Explanation

A radiometric thermal imager uses a rotating mirror with a single, fast response detector or a linear array of infrared (IR) detectors. This is used to measure successive areas with a single stationary device. Detectors sensitive to IR radiation need to be cooled to very low temperatures, usually by liquid nitrogen or helium, to function effectively. This is because everything in and nearby gives off IR waves. If the detectors are not cooled, they vibrate more forcefully than the signal being collected.

Just like a camera, the initial radiation detectors created two-dimensional images. However, a circular array of detectors that can be rotated is now used to craft three-dimensional images, a method deployed in X-ray computed tomography (CT) scans. In this process called single-photon-emission CT (SPECT), a spatial resolution technique, produces an image with a resolution of about 1 cm. Infrared telescopes also have cooled detectors to collect useful signals.

Modern detectors, such as charge-coupled devices (CCDs), are much more efficient. In these devices, radiation striking any part of the detector generates a stream of charged particles that are stored and counted at the end of exposure. Each radiation count location is a pixel, and modern detectors can count photons in millions of pixels (megapixels).