In short, what is infrared thermography?
Infrared thermography or thermal imaging is the use of special cameras that have the ability to see the infrared radiant energy that is emitted, reflected/refracted or transmitted from or through the surface of an object.
Depending on what type of infrared detector, sensor array and optical material that is used in the lens of the camera will, greatly, depend on the accuracy and sensitivity of the infrared camera. The newest technologies use uncooled microbolometers as focal plane array sensors. Their resolution is considerably lower than that of optical cameras, mostly 160x120 or 320x240 pixels, up to 640x512 for the most expensive models. Thermal imaging cameras are much more expensive than their visible-spectrum counterparts, and higher-end models are often export-restricted due to the military uses for this technology. Not all infrared systems are created equal.
All objects above absolute zero (0) Kelvin are radiating some amount of infrared energy and these types of cameras are able to image it and some can also quantify and measure it to infer what the temperature of an object is without having to touch it.
Images that are taken with an infrared thermographic camera are called "Thermograms" or a "Thermograph". The thermograms may be of two types depending on the capabilities of the imaging system and the requirements of the application:
Qualitative - an image that only shows the relative amounts of radiant energy compared to each other. (Finding a lost person in the woods.)
Quantitative - an image that not only shows the relative amount of radiant energy as described above but also has the ability to provide you with temperature measurements of the objects that you are viewing. (Elevated temperature screening.)
Thermography has a long history, although its use has increased dramatically with temperature screening applications within the last year due to COVID-19. Government and airport personnel used thermography to detect suspected swine flu cases during the 2009 pandemic. Firefighters use thermography to see through smoke, to find persons, and to localize the base of a fire. Maintenance technicians use thermography to locate overheating joints and sections of power lines, which are a tell-tale sign of impending failure. Building construction technicians can see thermal signatures that indicate heat leaks in faulty thermal insulation and can use the results to improve the efficiency of heating and air-conditioning units. Some physiological changes in human beings and other warm-blooded animals can also be monitored with thermal imaging during clinical diagnostics.
In short, quantitative thermal imaging is a non-contact and non-invasive method of spotting a person with an elevated temperature. The CDC considers a person to have a fever when he or she has a measured temperature of at least 100.4 °F [38 °C].
Learn more about thermography, attend the next thermography conference in 2021: https://thermosense.org/conferences/