| Thermal Imaging |
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THERMOGRAPHIC IMAGING Thermography, or '''thermal imaging''', is a type of Infrared imaging. Thermographic cameras detect Radiation in the Infrared range of the Electromagnetic Spectrum (roughly 900–14,000 nanometer or 0.9–14µm) and produce images of that radiation. Since infrared radiation is emitted by all objects based on their temperature, according to the Black Body Radiation Law , thermography 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 thermography allows one to see variations in temperature, hence the name. With a thermographic camera warm objects stand out well against cooler backgrounds. Humans and other warm-blooded animals become easily visible against the environment day or night, hence historically its extensive use can be ascribed to military and security services. Thermal imaging photography finds many other uses. For example, Firefighter s use it to see through Smoke , find persons, and localize hotspots of fires. With thermal imaging, Power Lines 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 . Some physiological activities, particularly responses, in human beings and other warm-blooded animals can also be monitored with thermographic imaging. {Link without Title} The appearance and operation of a modern Thermographic 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 Microbolometer arrays. Their resolution is considerably lower than of optical cameras, mostly only 160x120 or 320x240 Pixels . Thermographic cameras are much more expensive than their visible-spectrum counterparts, and higher-end models are often export-restricted. Older Bolometer s or more sensitive models require cryogenic cooling, usually by a miniature Stirling Cycle refrigerator or Liquid Nitrogen . See also: Infrared Camera THERMOGRAPHIC PRINTING Thermographic printing refers to two types of printing, both of which rely on heat to create the letters or images on a sheet of paper. The simplest type is where the paper has been coated with a material that changes colour on heating. This is called Thermal Printing and was used in older model Fax Machine s and is used in most Shop Till Receipt printers. This is called direct thermal. More complex is thermographic printing that melts print off a ribbon and onto the sheet of paper (thermal ink transfer printing). This is called thermal transfer. Thermography printing is also a post print process done inline with the printing. Thermography powder is sprayed on a sheet of paper after it leaves an offset printing press. It is then vacumed off of the sheet. The powder is left only where there was an image, or printed ink. The sheet then travels through a heat tunnel; there the heat causes the powder to melt and leave behind a raised image like on business cards, or envelopes. EXTERNAL LINKS
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