  thumb|movement of the seeker head of the iris-t infrared homing refers to a passive missile guidance system which uses the emission from a target of electromagnetic radiation in the infrared part of the spectrum to track and follow it. missiles which use infrared seeking are often referred to as "heat-seekers", since infrared (ir) is just below the visible spectrum of light in frequency and is radiated strongly by hot bodies. many objects such as people, vehicle engines and aircraft generate and retain heat, and as such, are especially visible in the infra-red wavelengths of light compared to objects in the background. the infrared sensor package on the tip or head of a heat-seeking missile is known as the seeker head. the nato brevity code for an air-to-air infrared-guided missile launch is fox two. 90% of all united states air combat losses over the past 25 years have been due to infrared-homing missiles.$96m to ds2 for laircm aircraft defense system support == seeker types == the three main materials used in the infrared sensor are lead(ii) sulfide (pbs), indium antimonide (insb) and mercury cadmium telluride (hgcdte). older sensors tend to use pbs, newer sensors tend to use insb or hgcdte. all perform better when cooled, as they are both more sensitive and able to detect cooler objects. early infrared seekers were most effective in detecting infrared radiation with shorter wavelengths, such as the 4.2 micrometre emissions of the carbon dioxide efflux of a jet engine. such seekers, which are most sensitive to the 3 to 5 micrometre range, are now called single-color seekers. modern infrared seekers also operate in the 8 to 13 micrometer wavelength range, which is absorbed least by the atmosphere. such seekers are called two-color systems. two-color seekers are harder to defeat with countermeasures such as flares. == scanning patterns and modulation == a missile's resistance to decoys can also be determined by the method in which the space in front of itself is scanned for targets. early missiles used so-called reticle seekers where the transparent plate with a sequence of transparent and opaque segments was placed in front of the ir detector elem
Infrared_imaging Missile_guidance