Identification Range: The maximum range at which a specified target can be identified, meaning distinction can be made between subclasses of like targets. For example, a target could be recognized as a tank, but identified as (in this example) a T-72 type tank. See Probability of Detection/Recognition/Identification.
IFOV: Acronym for Instantaneous Field Of View, which is the angle over which the detector senses radiation.
I2: Acronym for Image Intensification, which is a common night-vision technology that amplifies ambient visible light, by a factor of up to about 35,000. I2 cameras require at least a small amount of illumination, but can often be damaged by high illumination levels.
Illuminance: The inverse of exitance, the illuminance represents all of the light incident on a surface, expressed in terms of a flux density.
Indium Antimonide (InSb): Detector material used in some shortwave, cooled detectors.
Infinity Focus: The focus setting for objects far enough from the camera such that all targets at that distance or farther or in focus. See Hyperfocal Distance.
Infrared: That portion of the spectrum generally taken from about 800 nanometers (0.8 microns) to about 40 microns.
Infrared Imager: An imager or camera that is sensitive to energy in some portion of the infrared portion of the spectrum. Generally, there are three regions for infrared imagers; the “Near-Infrared” (NIR) region covers from about 0.8 microns to about 2.5 microns, the “Mid-Wave Infrared” (MWIR) covers from about 3 to 5 microns, and the “Long-Wave Infrared” (LWIR), which covers from about 7 to 14 microns. Often, the terms “infrared imager”, “thermal imager”, and “thermal infrared imager” are used interchangeably.
InGaAs: Indium Gallium Arsenide, a material used in near-IR detectors.
Integration Time: The time period over which the detector ‘views’ the target. Analogous to exposure time in visual cameras.
