Thermal sensors and cameras create video images from infrared (heat) waves. Infrared is a part of the electromagnetic spectrum with wavelengths that are longer than visible light. Infrared is typically divided into near, mid, long and extreme and is measured in units known as microns or nanometers. Thermal technology detects infrared energy in the mid-wave infrared (MWIR) spectrum at 3-5 microns or long-wave infrared (LWIR) at 8-12 microns. Day or night, in any environment, every person, object and structure emits infrared waves.
The warmer an object, the more energy it emits. Infrared energy emitted by a viewed scene is focused through the specialized objective lens assembly of an infrared camera on to the camera's focal plane array (FPA). The FPA uses materials that respond by generating electrical impulses when infrared energy strikes it. These electrical impulses are then sent in the form of temperature values to an image signal processor that turns them into video data for presentation on a display.
Thermal technology provides clear, high-resolution images through smoke, haze, dust, light fog or the darkest night, so it often is the perfect choice for 24-hour surveillance. For example, thermal cameras can pick out vehicles that have been driven recently and still have warm engines or ground that has recently been disturbed by footprints or by burying hidden objects.
Two types of thermal technology are available, each with its own advantages. For some devices, Leonardo DRS uses “uncooled” sensors which are built with a vanadium oxide (VOx) detector that allows for a very small camera size, low weight, minimal power requirements and high resolution. Leonardo DRS’ “cooled” systems employ mercury cadmium telluride (MCT) technology that utilizes a highly efficient cryogenic cooler that enables the detector to sense smaller differences in infrared emissions. Cooled technology often can capture images at a greater distance, produce a higher-resolution image and operate with smaller optics.
