Forward looking infrared (FLIR)

A thermal imaging sensor where sensor output is based on infrared radiation (usually between 3-5 or 8-12 micron spectral range) generated by the external scene. FLIRs are used for targeting acquisition and aircraft pilotage on both the AH-64 Apache and the newly developed RAH-66 Comanche.

References

http://www.usaarl.army.mil/hmdbook/cp_011.htm