NVG’s and EVS systems are entirely different. Each system has its own strengths and weaknesses. EVS systems utilize thermal imagery based upon Infrared sensors "microbolometers " that are heat sensitive and can detect temperature changes of less than 1/10th of 1 Degree C. These sensors detect Long-Wave Infrared (LWIR), Short-Wave Infrared (SWIR), or Mid-Wave Infrared (MWIR) energy, depending upon the manufacture and type of sensors being utilized. Astronics Max-Viz EVS systems utilize un-cooled LWIR microbolometer based sensors that detect energy in the 8-12 micron range, presenting that energy in a black and white "video appearing" format. This image can be displayed in the cockpit on dedicated displays as well as many multi-function, primary flight or primary navigational displays. The EVS image can also be presented in cabin displays as desired by the end-user.
Night Vision Goggles use light-amplifying technology. This technology takes the small amount of light that is available in the surrounding area (such as moonlight or starlight), and converts that light energy (scientists call it photons) into electrical energy (electrons) presenting an enhanced visible image to the pilot. These electrons pass through a thin disk that’s about the size of a quarter which contains more than 10 million channels. As the electrons go through these channels, they strike the channel walls and thousands more electrons are released. These multiplied electrons then bounce off of a phosphor screen which converts the electrons back into photons presenting a green- hued amplified re-creation (think T.V.) of the scene being observed through the NVG eyepiece.