Wil Gomez writing in Mac360 on Apple’s new 3D Face ID technology:
Think of 3D Face ID as a sensor system which holds an infrared transmitter and receiver capable of making measurements based upon the distance light travels, including light bounced off nearby objects, and that captures and records a face which is then used to unlock the iPhone, and permit Apple Pay to work. Just like the fingerprint with Touch ID but with your face.
How does it work?
iPhone 8 (or, iPhone Pro; that’s the name I would pick) has infrared transmitters which will spray invisible dots onto a person’s face, and then– because the camera can see infrared that humans cannot– measure the bounce time back to the phone’s infrared receiver. That creates a 3D mesh image of your face. It’s all done in real time, faster than Touch ID and with more accuracy and greater reliability.
And it works in the dark.