Infrared imaging is a technique of capturing the infrared light from objects and converting it into visible images interpretable by a human eye. The infrared region is spread across the 10 micrometer to 100 micrometer wavelength in the electromagnetic region which can be distributed into three bands: the Near-IR region from 0.7 microns to 1.3 microns; the Mid-IR region from 1.3 microns to 3 microns; the thermal-IR occupying the remaining part of the band. While the first two are used in general electronic applications like remote control and Illumination IR photography, the thermal IR is used in the thermal Imaging. The main difference is that the first two are used in reflective type of applications, while thermal IR is emanated from the object and not reflected by it.
Now the question arises, why only IR and why not any other part of the spectrum? The answer lies at the atomic levels. At absolute zero, perfect order is believed to exist in the atomic structure, no collisions and minimal entropy. Any object above the absolute zero temperature has atomic chaos and collisions resulting in thermal energy being radiated off it most of which falls in the IR band. Thus if these radiations can be detected by some means, objects can be visualized without the need of an optical source through their radiation patters. This forms the basis of infrared imaging.
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