Early MANPADS (Man Portable Air Defence Systems) would lock onto the exhaust plumes of aircraft and were countered by deploying flares. Modern Directed Infrared Counter Measures (DIRCM) use a sophisticated laser to disrupt the incoming missile’s infrared “heat-seeking” sensor:
With a laser energy source embedded in a highly agile enclosed turret system, a DIRCM can be infinite in duration and provide protection for the whole mission, keeping aircrews safe even in dense threat engagement environments.
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Whereas flares are omnidirectional, a DIRCM focusses a beam of light directly at an incoming missile. However, that beam of light needs to:
- Be able to have line of sight to the missile — a DIRCM with a twin or triple turret system allows for multiple threats to be countered simultaneously, no matter how the aircraft may be manoeuvring
- Be able to track and engage in a very short space of time — MANPADS can be supersonic in less than a second after firing
- Emit significant laser energy power to disrupt the missile seeker for long enough so the missile is unable to acquire, re-acquire or track the aircraft
So, you disrupt a missile’s tracking system by giving it a brighter signal source on its target?
Lasers are, by definition, single-wavelength. How long before the missile seekers are updated to ignore monospectral input?
Detecting and locking on a missile, with a laser in a turret small enough to not disrupt the flight profile of the aircraft, is much easier said than done.