LiDAR

It’s in the iPad Pro and coming to iPhones too. But what is it?

- Carrie Marshall

You’ve heard of sonar. You’ve heard of radar. But you might not know LiDAR, the distance sensing technology Apple added to the 2020 iPad Pro. Apple says it “delivers cutting-edge depth-sensing capabilities, opening up more pro workflows and supporting pro photo and video apps”.

It’s all about echoes

If you’ve ever shouted into a cave or in an empty building – and let’s face it, who hasn’t? – you’ll be familiar with echoes. When you shout, the sound waves you’ve made with your mouth reach the walls and bounce back to you, giving you an echo.

That echo tells you how far away something is. That’s because we know the speed of sound: at 20ºC/68ºF, sound travels through the air at just under 350 metres per second, so if your echo takes two seconds to return then you know the wall is about 700m away.

You’ve probably done those calculations yourself: for example, we’re writing this during a thunderstorm and we’ve been counting the seconds between the lightning flashes and the arrival of the thunder. It takes about three seconds for the sound to travel a kilometre and five seconds for it to travel a mile.

Sonar, radar and LiDAR do those sums with much more accuracy and with different kinds of waves. Sonar uses sound waves. Radar, radio waves. And LiDAR uses light: its acronym is short for Light Detection And Ranging.

So what does that mean for your iPad Pro?