Cyclic-error-free long-distance measurement using a frequency comb of a femtosecond mode-locked laser

High-accuracy long-distance measurement is performed using a broad and stable femtosecond frequency comb. Cyclic-error, which has been the main source of inaccuracy in conventional measurements, is reduced more than tenfold, directly achieving a world-record accuracy of 2-micrometers in a 240-m distance measurement.