The Pentagon has a laser that can identify people from a distance—by their heartbeat

The prototype can pick up on a unique cardiac signature from 200 meters away, even through clothes.

The news: A new device, developed for the Pentagon, can identify people without seeing their face: instead it detects their unique cardiac signature with an infrared laser.

Why it works: Our heartbeat can be used as a way to tell us apart. Other long-range biometric techniques exist, including gait analysis. But gaits, like faces, are not necessarily distinctive. And you can disguise or hide your face, unlike your heartbeat.

What is it: The device is a modified version of something usually used to check how much structures like wind turbines are vibrating. A gimbal was added so that a quarter-size laser spot could be kept on a target. Algorithms analyse the laser return to pick out a signature. Special Forces will probably be the tech's first users.

Issues and applications: One limitation is the need for a database of cardiac signatures, but it would be able to identify someone who has been seen for the second time. Doctors could also use it to scan for heart problems remotely and without wires. Read more here.

— David Hambling