Infrared sensors, on board the USS Discovery.

An infrared sensor is a type of photoelectric beam system used as an electronic alarm. It is designed to alert the user to an intruder's presence by transmitting infrared light beams across an area, where these beams may be obstructed. They are often used in military installations and other facilities of restricted access.


Infrared sensors are connected to a control unit via low-voltage wiring or a narrowband RF signal which is used to interact with a response device. In some cases, the sensors are linked directly to a facility's central command computer. If an intruder breaks the beams, an alert is raised and facility personnel are notified. There are two main types of infrared sensor: a stationary version where the beams are transmitted in a single position, and a patterned version where the beams continually change position so as to dissuade a potential intruder from attempting to pass though them.

A common method of making the sensor beams visible is through the use of infrared goggles or via cigarette smoke.

Infrated sensors can also be utilized with explosives, such as Semtex, to detonate if someone crosses the sensors unless the control box is shot out.


San Hieronymo Incident

Main article: San Hieronymo Incident
Warning: The following information is from outside Hideo Kojima's core "Metal Gear Saga." It has some level of canonicity within the continuity, but reader discretion is advised.[?]

The Soviet warhead storage facility on the San Hieronymo Peninsula utilized infrared sensors.

Non-"Metal Gear Saga" information ends here.

Phantom Pain Incident

See also: Hospital Escape and Phantom Pain Incident

Diamond Dogs' Mother Base utilized infrared sensors alongside similar installations owned by PMCs during the 1980s.

Outer Heaven Uprising

Main article: Outer Heaven Uprising

Outer Heaven utilized infrared sensors during the Outer Heaven Uprising in 1995.[1]

Zanzibar Land Disturbance

Main article: Zanzibar Land Disturbance

Zanzibar Land utilized infrared sensors during the Zanzibar Land Disturbance in 1999.

Shadow Moses Incident

Main article: Shadow Moses Incident

The nuclear weapons disposal facility on Shadow Moses Island used this type of sensor system, within both the armory and the tank hangar; the latter of which was linked to a nerve gas release system, that would activate upon the sensor being triggered.[2]

The Manhattan Incident

See also: Tanker Incident and the Big Shell Incident

During the Tanker Incident in 2007, the Gurlukovich Mercenaries proceeded to rig the ship with Semtex that had infrared sensors acting as a trigger to blow up the Discovery tanker, having planned to have the Marines ship scuttled after stealing the Metal Gear RAY prototype. Solid Snake ended up disabling this booby trap by shooting out the control boxes with the USP.[3] Two years later, during the Big Shell Incident, the Sons of Liberty at Solidus Snake's order had the Shell connection bridge laced with a similar Semtex trap with infrared sensor triggers, after being notified of a man in a cardboard box being onboard the Big Shell. Raiden ended up disabling the trap in a similar manner to Snake in the Tanker Incident under Iroquois Pliskin's advice.

Guns of the Patriots Incident

See also: Liquid Sun, Solid Sun, Third Sun, Twin Suns, Old Sun, and Naked Sin/Naked Son

Rat Patrol Team 01 had a similar booby trap in place with C4 as the explosive at Advent Palace, which they later used against Haven Troopers in the Middle East after their hiding spot was compromised.

World Marshal Incidents

See also: Raid at World Marshal, Ambush in Africa, Abkhazian Coup, Investigation in Guadalajara, Raid in Denver, and Operation Tecumseh
Warning: The following information is from outside Hideo Kojima's core "Metal Gear Saga." It has some level of canonicity within the continuity, but reader discretion is advised.[?]

The coastal refinery plant in Abkhazia possessed infrared sensors to protect against intruders.

Non-"Metal Gear Saga" information ends here.

Behind the scenes

Infrared sensors are a recurring trap in the Metal Gear series. Seeing them often requires either cigarette smoke or infrared goggles. In Metal Gear Solid: The Twin Snakes, because of the game incorporating gameplay elements from Metal Gear Solid 2: Sons of Liberty, the player can just shoot out the control boxes of the various infrared sensors in the Tank Hangar rather than trying to carefully navigate around the beams. Although they are generally a hazard to the player in the games, Metal Gear Solid V: The Phantom Pain introduces the concept of the player using infrared sensors as a defense system for their Mother Base's Forward Operating Bases. These security devices are considered Grade 3 and cost 1000 GMP for usage, and 100000 GMP for development.

In Metal Gear Solid: Portable Ops, if the player managed to clear out any and all enemies in the Soviet Warhead Storage Facility and then pass through the infrared sensor, although the device will ping repeatedly, it will not cause an alert due to none of the enemy soldiers being present or conscious to react.

Infrared sensor.
Intruder detection system that uses the infrared beam interruption method. Detects any individual who touches the beam, and sounds the alarm.
―IR-sensor description in the Metal Gear Solid V: The Phantom Pain Mother Base/FOB Gamescom 2015 gameplay demo



  1. ^ Metal Gear (re-release), Kojima Productions (2006).
    Big Boss: This is Big Boss... I forgot to tell you. Watch out for the infrared sensors. You'll need infrared goggles. ...Over.
  2. ^ Metal Gear Solid, Konami Computer Entertainment Japan (1998).
    Meryl Sliverburgh: Be careful, [Solid] Snake. That air lock is set with infrared sensors. You probably can't see them with your naked eyes, but there are infrared beams coming out of that wall. Touch any one of them, and the doors will seal off and the place will be flooded with poison gas. Somehow you've got to get through without setting off those sensors.
  3. ^ Metal Gear Solid 2: Sons of Liberty, Konami Computer Entertainment Japan (2001).
    Otacon: [Solid] Snake, wait! Don't move! // Solid Snake: I see it. Some kind of device on both sides of the hall... ...infrared sensors? // Otacon: Right. And they're linked to -- // Snake: Let me guess. Semtex. // Otacon: Exactly. Plastic explosives. // Snake: So this is what [the Gurlukovich Mercenaries] were talking about. // Otacon: Looks like it. If you trip the sensors... // Snake: I'll be sleeping with the fishes along with this entire ship. // Otacon: That sounds about right. // Snake: I'm not in the mood to go sleep with the fishes, but... There are too many sensors. Looks like I'll have to find another way. // Otacon: No need to worry. There's a way through. Take a close look -- do you see the thing with blinking green light right next to the explosives? That's the control unit for the sensors. Destroy that and the sensors stop functioning. You can't get close enough to touch it, so you'll have to shoot it out. But the M9's knockout rounds won't work. The USP you picked up should do the trick. Use that gun.