What is Time-of-Flight sensor and how does it work?

If you like to read about the new smartphones that come every now and then, you would have heard the term ‘Time-of-Flight’ sensor in the camera specs. While the rest of camera sensors be it single, dual or wide-angle are easy to understand and the way they function, the Time-of-Flight sensor, also called a ToF sensor is relatively tricky in its functioning. So, what is the ToF sensor?

ToF is not new and has been present in various devices, but has started coming to smartphones lately. In layman terms, a ToF sensor represents a type of technology that measures the time a laser, light, liquid, or gas-particle takes to travel a certain distance. The ToF systems cover ranges of a few centimetres up to several kilometres. The distance resolution is about 1 cm.

However, in the case of camera sensors, an infrared laser array sends out a laser pulse, and after striking at the subject in front of it, reflects back to the sensor. By measuring the time, it takes that laser to travel to the subject and back, allows you to calculate how far the subject is from the sensor, which further helps you to calculate a detailed 3D map of the room and all of the subjects in it.

The ToF technology is majorly used in drones and self-driving cars to avoid the collision but has also started coming to smartphones as well such as in the Huawei P30 Pro, which is used for depth mapping for portraits. Huawei also claimed that the P30 Pro can also measure the height, depth, volume, and area of real-world objects with greater than 98.5 percent accuracy.

In phones, ToF specifically, is used for 3D photography, AR, and in particular Portrait mode. The 2020 iPhones are also expected to come with ToF sensors to enable better depth maps for portrait mode pictures.