LiDAR (light detection and ranging) is a sensing method that fires laser pulses and measures how long each takes to bounce back from a surface. Distance follows from the speed of light, and many measurements combine into a 3D point cloud of the surroundings.
Why it matters
LiDAR gives direct, precise depth information, unlike a camera, which has to infer depth. It is used in autonomous vehicles, robots, drones, land surveying, and in some phones and tablets for faster autofocus and augmented reality. Performance can degrade in heavy fog, rain, or snow, and highly reflective or very dark surfaces can confuse it. It also costs more than cameras.
Some systems spin to scan all around, while solid-state designs have no moving parts. Phone LiDAR sensors use a small, short-range version suited for rooms rather than roads.
Example
Distance is the speed of light times the round-trip time, divided by 2. A pulse returning after 66.7 nanoseconds means the target is about 10 metres away:
d = (299,792,458 m/s x 66.7e-9 s) / 2 ~ 10 mA scan of many thousands of such points per second reconstructs the shape of a room or street.
Common mistakes
- Assuming LiDAR sees through fog and glass.
- Comparing range figures without noting the target's reflectivity.
- Confusing it with radar, which uses radio waves, or a plain infrared proximity sensor.
Related
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