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What is infrared light?
In one sentence: Light just beyond red that our eyes can't see. TV remotes and face unlock cameras use it.
A little more
Infrared is light with waves a little longer than red light. Our eyes can't see it, but cameras can be built to. A TV remote flashes infrared to send its buttons, and warm things give it off, which is how heat cameras work.
Phones with depth-sensing face unlock spray tens of thousands of invisible infrared dots onto your face and read where they land, which gives a 3D shape of your face even in the dark.
It's a bit like… A torch that only cameras can see, like a secret colour.
See it in action
- BonusHow does a TV remote work when nothing comes out of it?Press a pretend remote and see the invisible infrared flashes it sends: a wake-up flash, 32 bursts with long and short gaps, and a 38,000-a-second flicker that stops sunshine fooling the TV.8 min · interactive
- 11How does face unlock know it's you?Design a face, set up a pretend face unlock and see who gets in: you in glasses, your twin, a stranger, a printed photo.7 min · interactive