<unk>  thermal imaging, or thermal video, is a type of infrared imaging.<unk> c cameras detect radiation in the infrared range of the electromagnetic spectrum (roughly 900–14,000 nanometers or 0.9–14 µm) and produce images of that radiation. Since infrared radiation is emitted by all objects based on their temperatures, according to the black body radiation law,<unk> makes it possible to "see" one's environment with or without visible illumination. The amount of radiation emitted by an object increases with temperature, therefore<unk> allows one to see variations in temperature (hence the name).<unk> c images are direct measurements of sympathetic skin galvonic impedance. When viewed by<unk> c camera, warm objects stand out well against cooler backgrounds; humans and other warm-blooded animals become easily visible against the environment, day or night. As a result,<unk> s extensive use can historically be ascribed to the military and security services.
Thermal imaging photography finds many other uses. For example, firefighters use it to see through smoke, find persons, and localize the base of a fire. With thermal imaging, electric power line maintenance technicians locate overheating joints and parts, a telltale sign of their failure, to eliminate potential hazards. Where thermal insulation becomes faulty, building construction technicians can see heat leaks to improve the efficiencies of cooling or heating air-conditioning. Thermal imaging cameras are also installed in some luxury cars to aid the driver, the first being the 2000 Cadillac DeVille. Ever since the SARS outbreak of 2003 airports have also found utility in screening airport passangers for fever.
The largest medical application for infrared thermal imaging includes those musculoskelatal pain conditions that are weather sensitive (RSD, CRPS, Fibromyalgia, Thoracic Outlet Syndrome, etc). In this instance sympathetic skin response is mapped through cold exposure over time.  Sympathetic skin responses, skin galvonic impedance and thermal asymmetry patterns all overlap with each other] Internationally peer reviewed guidelinesfor neuromusculoskeletal<unk> were adopted in 2006.
Breast thermal imaging has also been used to assess for cancer.  Serial studies over time are used for comparative purposes in this application. Some physiological activities, particularly cold stress response in human beings and other warm-blooded animals can also be monitored with<unk> c imaging
The appearance and operation of a modern<unk> c camera is often similar to a camcorder. Enabling the user to see in the infrared spectrum is a function so useful that ability to record their output is often optional. A recording module is therefore not always built-in. Instead of CCD sensors, most thermal imaging cameras use CMOS Focal Plane Array (FPA). The most common types are InSb, InGaAs, QWIP FPA.
The newest technologies are using low cost and uncooled microbolometers FPA sensors. Their resolution is considerably lower than of optical cameras, mostly 160x120 or 320x240 pixels, up to 640x512 for the most expensive models.<unk> c cameras are much more expensive than their visible-spectrum counterparts, and higher-end models are often export-restricted. Older bolometers or more sensitive models as InSB require cryogenic cooling, usually by a miniature Stirling cycle refrigerator or liquid nitrogen.
Thermography 
Angiogram
Lymphangiogram
Venography
Tourniquet test
Palpation
Spectroscopy
Impedance phlebography