Fig. 3: Elimination of dead zones.
a Dead zones are regions where the probe and reference interferograms heavily overlap so that they cannot be distinguished from each other via pulse fitting, but such an overlap is measurable by using DFT. b Measured interferometric traces, here the to-target distance is 2 mm and the almost completely overlapped two pulses form clear interference fringes due to the DFT. c Fast Fourier transform spectra when the to-target distance increases from 10 μm to 10 mm. d Measurable region. The minimum detectable distance of DFT-based dual-comb ranging is only determined by the detection accuracy. e Parametric limitation for reaching the dead zone free measurement.
