Laser ranging sensors and methods that use a ladder of synthetic waves having increasing wavelengths to calculate a distance measurement

Abstract

Systems and methods for measuring a distance to an object. An exemplary method includes directing light beams from three or more continuous-wave lasers onto a target, and also frequency shifting the light beams split off from the lasers to generate local oscillator beams. When the reflected sensor beam (reflected off the target) and the local oscillator beams are combined, the method further includes determining optical phases of heterodynes produced by combining the light beams within the reflected sensor beam and the local oscillator beams, and determining synthetic phases by taking the difference between the optical phases of the heterodynes. The method further includes determining synthetic wavelengths based on the differences between the frequencies of the lasers. The method further includes determining a distance to the target based on the synthetic phases and the synthetic wavelengths.