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The Thermal Laser Weapon is a device that attaches to standard rail system on military rifles. Like the vehicle-mounted Active Denial System, it works by heating up the outer layer of skin, causing a very painful burning sensation without — in theory — causing any actual damage. The Active Denial System uses short microwaves, the Thermal Laser Weapon uses an infra-red laser. Work on the device is a direct outgrowth of the work on thermal lasers described in Danger Room last year; field testing of the Thermal Laser Weapon by the Joint Nonlethal Weapons Directorate was announced this week.

The Thermal Laser’s immediate ancestor was the PHaSR (allegedly short for “Personnel Halting and Stimulation Response,” although the makers confess to being Star Trek fans). The PHaSR was a big, bulky weapon which combined an infra-red laser with a laser dazzler to produce a repel effect. Only the heating effect is mentioned for the Thermal Laser, but it seems likely that a visible laser would also be incorporated if only as an adjunct to aiming. The photo here shows the Saber 203, an earlier rifle-mounted dazzler.

The Active Denial System puts out around 100 kilowatts and illuminates an area about two meters across. And it produces a powerful “goodbye effect”: After several thousand tests, noone has been able to withstand it for more than five seconds moving out of the beam’s path. However, it’s not clear how effective a narrow beam of just a few watts would be, and this is what the designers of the Thermal Laser Weapon are trying to establish. The recent field evaluations highlighted one of problems with using infrared: Microwaves will go through any clothing, and can only be stopped by encasing yourself in tinfoil, but infrared can be blocked by clothing.

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