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Although there’s a lot technology can’t do, imaging technology in the darkness of night can improve the human eye. There’s a wide assortment of quick, deployable solutions for night surveillance. Your desired field of view (FOV) and covert level of your operation will determine which of these four technology examples is best suited for your application.
True day/night cameras come equipped with an automatic IR-cut filter that is removed from the image sensor to let IR-spectrum light flow into the camera at night. When working in harmony with an IR illuminator (see next column), a day/night camera will provide even more visibility. Beware of imitation “day/night” cameras that merely switch the color to black and white to give the illusion of night vision.
Infrared (IR) illumination
IR illumination boosts imaging capabilities at night by taking advantage of the full light spectrum. Today’s sophisticated digital image sensors provide a detailed forensic image when working with IR illuminators. They can be used as stand-alone units or integrated into the video camera itself. Keep in mind that these devices will wash an area with IR light only in the direction that the unit is pointed, so the camera’s entire FOV may not have full visibility.
For sophisticated operations, a more covert level of IR might be required. IP-based technology provides an intelligent and covert way to take advantage of boresighted IR devices to precisely pin-point the target area of your investigation. This coupled with a more covert level of IR (920 nanometers or higher, which is invisible to the naked eye) will reduce the chance that the operation will be detected. With any IR application, check the camera’s performance specifications against the desired IR illumination function.
Although thermal technology has been around for decades, it’s historically been limited to military and government applications due to cost. Thanks to changes in component demand, there are affordable thermal cameras available today that use the same high-quality imagers. Since these imagers register heat variations in a scene, they detect humans and objects in complete darkness as well as difficult weather and smoke. While thermal should be used for detection, not identification, it can also provide an additional level of forensics by detecting the heat signatures on a vehicle, a cold gun in someone’s hand, or even silhouetted impressions that have been left behind.