Time-stretch LiDAR as a spectrally scanned time-of-flight ranging camera

The need for imaging and ranging in robotics has brought LiDAR (light detection and ranging) to the forefront of consumer technology(1). Among various approaches, time-of-flight ranging sets the benchmark for robust operation due to illumination with high-energy pulses and direct detection. Conversely, spectrally scanning using tunable lasers is an inertia-free solution that offers fast scanning. The realization of a time-of-flight LiDAR with fast spectral scanning has not been possible because of difficulty in creating pulsed tunable sources. We demonstrate a wavelength-scanned time-of-flight LiDAR that realizes single-shot imaging and inertia-free scanning in one dimension with a rate of 1MHz using a single laser and a single detector. We report two implementations of this concept, the first with a gain-switched supercontinuum source at 1,550nm, and the second with a frequency-domain mode-locked laser at 1,060nm. We show foveated imaging with both approaches as a potential solution to the big data predicament in three-dimensional imaging. A wavelength-scanned LiDAR offers high spatial resolution and can dynamically adapt to fast moving scenes.