US Patent 10901087 Time of flight camera

A method of determining distances to features in a scene comprising transmitting structured light modulated at a modulation frequency to illuminate the scene with a structured illumination pattern and for each combination of a sampling phase offset ψk and a perturbation phase shift λn, modulating sensitivity of a photo sensor at the frequency of modulation of the transmitted light, but phase shifted relative to phase of the transmitted light by a phase θk,n=(ψk+λn), and for each value of θk,n modulo 360°, registering light reflected by features in the scene during a different exposure and using the registered light to provide a range image of the scene.