Military Infrared: The Role of Infrared Lighting in Modern Operations
Military infrared is the use of near-infrared light, which the unaided eye cannot see but night vision devices can, to mark friendly troops and vehicles, to drive and move in convoy without visible lights, to illuminate and aim, and to signal to aircraft. It works because a force equipped with image intensifiers can see light that an unequipped observer cannot.
That advantage holds only against an adversary without the same equipment. Any opponent with night vision sees the same light, so every use of active infrared is a trade between what it gives the user and what it shows the enemy. This article sets out how forces use IR in each role, where that trade sits, and what it means when IR equipment is specified for vehicles and crews.
Active Emitters and Passive Sensors
Two kinds of equipment share the word infrared, and the difference between them drives everything else in this article.
Image intensifier tubes amplify whatever light is present, starlight and moonlight included, and they respond beyond the visible band. Second-generation tubes are sensitive from about 400 nm to about 900 nm and third-generation tubes from about 600 nm to a little over 900 nm, against roughly 400 to 700 nm for the human eye. A source emitting just beyond the visible band is therefore bright through a goggle and dark, or nearly so, to the eye. That is active infrared: an emitter that adds light for the tubes to see. Betalight’s IR vehicle lamps emit between 770 and 940 nm depending on the model, and the choice between 850 and 940 nm trades a brighter goggle image against a faint red glow at close range.
Thermal imagers work differently. They detect heat emitted by the scene itself, in the long-wave band of about 8 to 14 µm, and need no illumination at all. They do not show a near-infrared marker or aiming laser, which is why forces that field thermal sights still carry IR emitters. Short-wave infrared (SWIR) cameras, working from about 1,000 to 2,500 nm, form a third group: they image reflected light beyond the reach of intensifier tubes, so a marker meant for a SWIR sensor has to emit in that band.
From Searchlight Sniperscopes to Third-Generation Tubes
The first military infrared systems were all active. A filtered lamp lit the target and an image converter showed the result, which made them heavy and short-ranged: the German Zielgerät 1229 “Vampir” sight of 1945 weighed 2.26 kg, and the battery for its lamp a further 13.59 kg. What changed the picture was the passive image intensifier.
The lesson of that history is that viewing went passive while emitting did not disappear. Since the 1960s an intensifier no longer needs its own lamp to see, so active IR has moved from lighting whole scenes to narrower jobs where a deliberate, controllable source is worth its signature: marking, identification, vehicle movement, aiming and supplementary illumination.
IR Marking and Identification
Marking is the use that matters most to most units. A military IR strobe on a helmet, an IR-reflective patch on a sleeve or a beacon on a vehicle roof turns an anonymous shape in a goggle image into a known friendly, for the soldier alongside, for a vehicle commander and for aircrew or drone operators overhead. The aim is positive identification without a visible signature on the ground.
Signalling uses the same sources. Briefed patterns from strobes and IR chemical lights mark a landing zone, a casualty collection point or a unit boundary, and the US Army’s NVG driving circular tells a stopped crew to warn approaching goggle drivers with an IR lightstick. What a pattern means is set by the unit’s orders, not by the equipment, as our article on tactical lighting for communication and coordination explains.
Betalight’s identification products follow the same split between soldier and vehicle. The Trilobyte IR helmet strobe signals in white, green, red or near infrared, with a visibility range of up to 5 km on high intensity. The IR Beacon for vehicles is specified at 850 or 940 nm, carries a unique pre-programmed flash pattern per unit and mounts on an integrated magnetic base, giving aircrew and overwatch a positive identification of the vehicle.
Driving and Convoy Movement on Goggles
Vehicle movement at night is where IR lighting earns its place on the platform rather than on the soldier. Goggle driving performance depends on the light available, and the US Army relates it directly to starlight and moonlight. When there is too little, an IR driving lamp adds light that only the driver’s tubes use. In a convoy, IR rear lamps let the following driver hold spacing and see braking on goggles while showing nothing to the unaided eye.
IR lamps do not replace the visible tactical set. The blackout lamps on a NATO vehicle serve crews driving without goggles, and they must themselves be free of IR: ČOS 254001, the Czech implementation of STANAG 4381 Ed. 2, limits their output in the 700 to 1,200 nm range to 1 % of peak. Visible blackout lamps and IR lamps are therefore separate functions, selected through the vehicle’s light switch, and most tactical vehicles carry both. Betalight supplies military blackout lights for the visible side and infrared lights for the goggle side.
The IR range covers the positions a vehicle needs: the Infrared Driving Light (770 to 840 nm, visibility 75 to 100 m), the Infrared Vehicle Headlight with a 940 nm low beam and an 850 nm high beam, the Infrared Convoy Brake Light (850 to 940 nm), which marks the rear and warns of braking, and the Infrared Tail Light. How these lamps work with the tubes and the tactical light switch is covered in our article on infrared vehicle lighting.
Illumination and Aiming
An IR illuminator is a flood or spot source that lights a scene for goggles when ambient light is too low: inside buildings, under canopy or on an overcast night. Beam divergence decides the job, wide for close work and narrow to reach further. On weapons the illuminator is usually paired with a military IR laser for aiming, so the firer can aim through a goggle without bringing the weapon to the eye.
The L3Harris AN/PEQ-15 (ATPIAL) illustrates the type. Its specification sheet lists an IR aiming laser at 835 nm with 700 µW in low power and up to 27.5 mW in high power, and an IR illuminator at the same wavelength with up to 45 mW and a divergence adjustable from about 1 to more than 105 mrad. Those figures matter to a buyer because they set the laser class, and with it the training and range rules (see the FAQ).
On vehicles the same functions move to the turret and the mast. Betalight’s Military Light Laser Module, designed for the Kongsberg Protector RS4 remote weapon station, combines an IR LED flood light with a Class 3B IR laser, and the Remote Controlled Searchlights provide visible and IR output in one head for search and overwatch.
The Counter-Detection Trade-Off
Every role above shares one weakness. Active IR is hidden from the eye, not from sensors.
The risk has grown with the sensors. Image intensifiers are no longer the only threat: standard CMOS camera sensors still respond at 850 nm, although their quantum efficiency is very poor at 940 nm, and NIR-enhanced sensors extend that response. SWIR cameras on drones and sights see beyond the tube band altogether.
Units manage this through IR discipline, the active counterpart of light discipline: emit only when a task needs it, at the lowest output and for the shortest time that does the job, pointed away from likely observers, with patterns and periods of use briefed in advance. Where the threat is known to have night vision, viewing stays passive, on intensified ambient light or thermal, and IR sources are kept for the moments when marking or aiming is worth being seen. Choosing 940 nm reduces the visible glow at the cost of a dimmer goggle image, but it does not hide a source from an image intensifier.
What to Settle Before Ordering IR Equipment
Most problems with military infrared in service trace back to questions that were not asked at specification. Settle these before a quotation is requested:
- The fleet’s viewing devices: Gen II, Gen III or digital, because their spectral response decides which wavelengths are useful.
- The role of each source: marking, driving, illumination or aiming, and who has to see it (crew, convoy, aircrew or drone).
- Switching: how IR lamps are selected relative to the visible blackout set, and whether the light switch has a night vision position.
- Patterns: for strobes and beacons, the flash patterns, how they are programmed and whether SWIR visibility is needed.
- Laser class and export classification: for every mode of every laser, and for the destination country.
Where a platform needs a wavelength, pattern or housing the catalogue does not carry, Betalight builds to specification.
Frequently Asked Questions
Yes. A thermal imager reads heat in the long-wave band and does not show a near-infrared strobe, patch or aiming laser, so it cannot see friendly IR marking. Thermal is the better detector in darkness, smoke and against camouflage; image intensifiers with IR marking remain the tools for identifying friendly forces and aiming at night. Most forces carry both, and fusion devices combine the two in one view.
Not automatically. Near-infrared light does not trigger the aversion response that limits exposure to bright visible light, so a hazardous beam gives no warning. Lasers are classified under IEC 60825-1:2014 (edition 3.0): the AN/PEQ-15’s IR aiming laser is Class 3R in low power and Class 3B in high power, and its IR illuminator is Class 3B in both. Direct viewing of a Class 3B beam is normally hazardous, so ask for the class of every mode and set training rules to match.
Often, depending on the item and the destination. In the United States, IR aiming and target illumination systems and many image-intensified goggles and sights fall under Category XII of the US Munitions List (Fire Control, Laser, Imaging, and Guidance Equipment), as revised by the final rule effective 31 December 2016. In the EU, equipment specially designed for military use is listed in the Common Military List, where ML15 covers imaging or countermeasure equipment. Whether a particular lamp, beacon or illuminator is controlled depends on its design, so ask for its export classification with the quotation.