OVERVIEW: Infrared Search and Track (IRST) 1st Generation (non-imaging) systems are passive infrared sensors used primarily for target detection and tracking without emitting any signals, providing covert surveillance capability.

GENERAL DESCRIPTION: First-generation IRST systems utilize non-imaging infrared detectors to scan for heat signatures of aircraft or missiles, typically covering mid-wave IR bands. These early IRST sensors detect changes in infrared radiation to locate targets but lack detailed image formation, limiting identification capabilities. Commonly installed on fighter aircraft and naval vessels from the 1960s to 1980s, they offer passive long-range detection useful in environments where radar use is restricted or undesirable.

ROLE SUMMARY:
Category: Passive Infrared Target Detection
Primary Use: Detection and tracking of airborne targets using IR emissions
Function: Passive scanning of infrared energy for situational awareness and early warning
Platform: Fighter aircraft, maritime patrol aircraft, naval ships
Integration: Often coupled with radar and fire-control systems for target engagement

See Specific information under [Sensors/EW] and [Properties] sections.

SOURCE:
Defense Technical Information Center (DTIC)
https://en.wikipedia.org/wiki/Infrared_search_and_track