Use of Infrared in Surveillance

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Use of Infrared in Surveillance

Abstract: This paper begins with an introduction into the discovery and description of infrared radiation by Sir William Herschel in 1800. It follows by describing various uses of infrared for surveillance purposes. The first application described is the role of infrared in active and passive Night Vision Devices (NVD's) for both military and recreational use. It describes the basic functions of these devices and the differences between the uses and benefits of both active and passive scopes. The second application is the use of infrared in the early detection of missile launches and the estimation of impact points. In a similar military role, infrared is also used to detect land mines hidden throughout various parts of the globe. Finally, infrared is used in home or business surveillance through a system that uses an infrared camera to create a thermogram.

Infrared

Infrared accounts for the portion of the electromagnetic spectrum that extends from wavelengths of 0.75 to 1000 microns. This portion of the spectrum is invisible and lies beyond the red end of the visible spectrum. Infrared rays are much longer than those of the spectrum colors but shorter than radio waves and have a penetrating heat effect. For this reason, infrared rays are often called heat rays.

Infrared was discovered accidentally in 1800 by Sir William Herschel. In an experiment being conducted for uses other than the discovery of infrared, Herschel used a glass prism to break light into its component colors, a discovery already long-since made by Newton. However, by moving a thermometer across the spectrum, Herschel noted that the temperature increased as it moved from violet to red, reaching a maximum temperature in the dark region beyond the visible spectrum. He named this region infrared radiation.

Applications

Night Vision Devices (NVD's)

Infrared was first linked with technology during World War II with the invention of the sniperscope. The sniperscope was used to detect infrared rays from objects warmer than their surroundings in an effort to "see in the dark." The invention worked on the knowledge that any object with a temperature above absolute zero is a natural radiator of infrared energy. This infrared radiation results from the acceleration of electrically-charged particles within the material. The warmer the object, the greater the emission of particles from the increased acceleration.

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