Frequency-Modulated Continuous-Wave LiDAR

A lidar that continuously emits frequency-swept laser light, measuring both distance and velocity at every point.

This is one of the ranging methods used in lidar. The common time-of-flight (ToF) lidar emits short pulses and times the round trip of the echo; FMCW lidar instead continuously emits laser light whose frequency sweeps periodically over time, mixes the returning echo coherently with a local copy of the light, and reads distance from the resulting frequency difference, while the Doppler shift directly gives that point’s velocity along the line of sight — which is why vendors often call it 4D lidar. It only responds to light matching its own frequency and wavelength, so it’s much less affected by sunlight or crosstalk from other lidars; it commonly operates in the 1550 nm band, where eye-safety limits allow higher power. The cost is that it needs coherent transceiver components, making it structurally complex and expensive. It’s currently used mainly in autonomous driving, with vendors like Aeva and Aurora; robots still mostly use ToF lidar.

ExampleEvery point from an Aeva FMCW lidar carries a velocity value in addition to its 3D coordinates, so a single frame can separate a walking pedestrian from a stationary pole without comparing two consecutive frames.

Also called

FMCW LiDAR, Coherent LiDAR, 4D LiDAR

Related

LiDAR · Time of Flight · Solid-State LiDAR · Millimeter-Wave Radar · Autonomous Driving · Multi-Sensor Fusion

Sources

Aurora: FMCW Lidar — The Self-Driving Game-Changer
Aeva 官网（FMCW 4D LiDAR） (Chinese)
Wikipedia: Continuous-wave radar（FMCW 原理） (Chinese)

As of

2026-09