Thermal Weapon Sight – AN/PAS-13

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There’s more than one way to see in the dark.

In this article, we’re going to take a close look at a thermal weapon sight used by the U.S. Army, Marine Corps, and others.

The AN/PAS-13 is a Thermal Weapon Sight used in the US military.

AN/PAS-13 Thermal Weapon Sight mounted on an M240B machine gun.
A soldier peers through a AN/PAS 13 thermal weapon sight mounted on a M240B machine gun during Operation Cold Steel III. (U.S. Army Reserve photo by Staff Sgt. Christopher J. Sofia)

It enables night vision capabilities, although thermal sights are useful in the daytime too.

Night Vision Goggles (NVGs) and other Night Vision Devices (NVDs) mostly use Image Intensification (I2) technology to amplify the available ambient light to something that a person can see.

But, thermal vision or “heat vision” is also a way to see at night.

View using thermal vision
Thermal sights like the AN/PAS-13 use digital electronics to show the differences in background temperatures. In this view, white is “hot”. (Photo by Program Executive Office)

Thermal vision utilizes digital devices to present to the user an image showing the temperature differences in a scene.

This works particularly well for objects (people, animals, and vehicles) that have a temperature significantly different than the background.

Best of all, thermal vision works day or night – unlike I2 light amplification devices.

It also works in smoke, fog, dust, and haze.

View through an AN/PAS-13 Weapon Thermal Sight
Vehicles and targets are seen through the green hued screen of an AN/PAS-13E Thermal Weapon Sight. These devices are largely based on digital electronics as you can see from the various symbology on the display. (U.S. Army Reserve photo by Staff Sgt. Christopher J. Sofia/78th Training Division)

The AN/PAS-13 Weapon Thermal Sight

The AN/PAS-13 Thermal Weapon Sight (TWS), AN/PAS-13 family enables soldiers with individual and crew served weapons to see deep into the battlefield, increase surveillance and target acquisition range, and penetrate obscurants, day or night.

The TWS systems use uncooled, forward-looking infrared technology (IR) and provide a standard video output for training, image transfer, or remote viewing. Thermal weapon sights are lightweight systems that are mountable onto a weapon rail and operate to the maximum effective range of the weapon.

As a “family” of weapon sights, there are actually 3 distinct versions.

The AN/PAS-13(V)1 Light Weapon Thermal Sight (LWTS) is meant for the M16 and M4 series of rifles and carbines, as well as the AT4/M136 Light Anti-Armor Weapon.

It weighs 1.8 lbs.

AN/PAS-13 light weapon thermal sight (LWTS) (
The AN/PAS-13 light weapon thermal sight (LWTS) is meant for use on the M16, M4, and AT4.

The Thermal Weapon Sight (TWS) AN/PAS-13(V)2 Medium Weapon Thermal Sight (MWTS) is for the M249 Squad Automatic Weapon (SAW) and M240B series medium machine guns.

But, it can be used on M16 and M4 series weapons as well.

It can detect a human sized target at 1.2 kilometers range.

It has a 5x zoom capability and weighs 2.8 lbs.

AN/PAS-13 MWTS mounted on an M240 Machine Gun
An AN/PAS-13 Medium Weapon Thermal Sight (MWTS) mounted on an M240 machine gun. (U.S. Army Reserve photo by Spc. Brianna Saville/416th Theater Engineer Command)

There’s a version of the AN/PAS-13 meant for heavy weapons too, like the M2 .50 caliber machine gun.

It has longer range than the Medium or Light version.

AN/PAS-13 Heavy Weapon Thermal Sight (HWTS)
The AN/PAS-13 HWTS is meant for heavy weapons with long range – like the M2 .50 caliber machine gun, MK19 Grenade Launcher, and sniper rifles – but it can be used on the M4/M16 as well.

It has a 10x zoom capability and weights 3.9 lbs.

A human sized target can be detected at 2.8 kilometers range.

The Thermal Weapon Sight (TWS) AN/PAS-13(V)3 Heavy Weapon Thermal Sight (HWTS) for the squad leader’s weapon, M16 / M4 series rifles and carbines, M24 and M107 sniper rifles, and M2 HB and MK19 machine guns.

AN/PAS-13 HWTS mounted on M2 machine gun
AN/PAS-13 Heavy Weapon Thermal Sight (HWTS) being used mounted on an M2 machine gun – and hand-held. (U.S. Army Reserve photo by Spc. Brianna Saville/416th Theater Engineer Command)

These Weapon Thermal Sights are useful as handheld optics as well.

Handheld use of the AN/PAS-13
A soldier views the range through a AN/PAS-13 Thermal Weapon Sight in preparation for sending the first rounds downrange for weapons qualification. (U.S. Army photo by Sgt. Heather Doppke/79th Theater Sustainment Command)

AN/PAS-13 – How it Works

The AN/PAS-13 uses a high-sensitivity mercury cadmium telluride (HgCdTe) focal plane array (FPA) to provide long-range target recognition with relatively small telescopes.

It also uses a thumbnail-sized thermoelectric cooler ensures silent operation and high reliability.

The sight does require a 1-2 minute “cooldown” period before it can be used.

AN/PAS-13 HWTS mounted on an M2 50 caliber heavy machine gun
The longer range and zoom of the AN/PAS-13 HWTS is a necessity for long range weapons such as the M2 machine gun. (U.S. Army photo by Sgt. Heather Doppke/79th Theater Sustainment Command)

AN/PAS-13 Weapon Thermal Sight – In Summary

The AN/PAS-13 family of weapon thermal sights consists of 3 versions: Light, Medium, and Heavy.

These weapon sights use thermal vision technology to allow a view in day or night conditions.

The AN/PAS-13 is not available for commercial sale.


AN/PAS-13 (Wikipedia)

Photo Credits

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Some of the photos in this article are provided by the U.S. Department of Defense (DoD), or the manufacturers – and are the property of the manufacturers.

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