Fig. 2: Single point ranging.
a Measured interferogram of our dual-comb ranging system, the periodic pulse enhancements demonstrate the macroscopic information of distance, which relates to the m × TOF. b Zoom-in of the ‘Local-Reference’ peak and the “Local-Probe” peak. Due to the DFT, minor pulse-to-pulse delay-based fringes are clear. c Fast Fourier transform spectra of the fringes, here frequencies fi1 to fi4 correspond to the delays τ1 to τ4. d Zoomed-in spectrum of the fi1 peak, with 3-dB bandwidth 2.9 MHz and SNR 32 dB. e Repeated ranging results and their distribution, suggesting a maximum error ± 1.3 μm and an RMSE 288.7 nm. f Precision of the distance measurement versus averaging time. Allan’s deviation reaches 2.8 nm with an averaging time 1.5 ms. g Correlation of the measured distance and the real distance. Here the blue dots show the range using one comb with 24.465 MHz, while the orange dots show the expansion using Vernier dual combs.
