Absolute Distance Measurement Using Frequency Comb and a Single-Frequency Laser

We propose, here, a multi-heterodyne method using frequency comb and a tunable laser for absolute distance measurement. Numerous beat frequency components can be obtained in RF region. The distance can be determined via the phases of the beat signals. We potentially extend the non-ambiguity range up to 105 m by adjusting the comb repetition frequency slightly. The experimental results show an agreement within 4.5 μm, corresponding to a relative precision of 1.5 × 10^-7 in a range up to 30 m, compared with an incremental distance meter.