Thermal imagers (TI) use passive infrared sensors to detect IR radiation given off by warm objects which is then translated into a visible picture for the device's operator. Particularly effective at night when ambient heat is less, a good thermal imager can show up the heat given off from people, vehicles and enemy positions. Thermal imagers are a superb tool for battlefield reconnaissance.
Thermal imagers can be dedicated units or part of target acquisition systems on weapons such as anti-tank missile launchers. Types in use in the UK military include :
- OBSERVER'S THERMAL IMAGING SYSTEM (OTIS)
a tripod-mounted TI with built-in laser range finder often used for fixing a target's position for air or artillery strike. The OTIS can spot targets up to 6kms away.
hand-held or tripod-mounted Thermal Imager with day/night capability and an acquisition range of 2.5km.
- JAVELIN MISSILE
the command launch unit (CLU) of this anti-tank missile contains a sophisticated thermal imaging sensor that can double as a reconnaissance tool.
- MILAN MISSILE
the soon-to-be obsolete Milan wire-guided anti-tank missile system features a MIRA thermal imaging sight, with a range of 4km.
- APACHE GUNSHIP TADS
the Target Acquisition Designation Sight (TADS) sensor suite in the nose of the WAH-64 Apache helicopter, whilst primarily designed to find enemy armour, can also sweep the ground for troops.
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Use of Thermal Imagers by UK Special Forces and Elite Troops
UK Special Forces first reported use of a thermal imager in a conflict was during the Falklands campaign in 1982. On the night before the main British landings, the Special Boat Service (SBS) used a spyglass thermal imager to locate an Argentine force atop Fanning Head. When combined teams of SBS and 148 Bty Naval Gunfire Specialists inserted by boat onto West Falklands, they used a TI to scan the shoreline for Argentine troops.
Working deep behind Iraqi lines during Desert Storm, SAS Landrover columns used the MIRA sights from their MILAN launchers to scout the desert for enemy forces.
In more recent actions, 45 Commando, Royal Marines are known to have used tripod-mounted TIs during Operation Ptarmigan, their hunt for Taliban and Al-Qaeda fighters in high mountain valleys of Afghanistan.
When 3 PARA deployed to Helmand Province, Afghanistan, in 2006, they found that the TI sights of the new Javelin missile to be an a invaluable aid for spotting Taliban forces hiding out in the darkness.
Thermal imagers also have a role in counter terrorism operations. In some circumstances, TIs can be used to locate people through the walls of a building, helping the SAS to build up a picture of what's happening inside.