Fig. 1. FSI ranging system based on fiber auxiliary interferometer

Fig. 2. Influence of temperature variation on distance measurement accuracy of FSI system

Fig. 3. Influence of dispersion mismatch on distance measurement accuracy. (a) Phase residual for different distance; (b) measurement error for different distance

Fig. 4. Gas absorption cell calibration system based on femtosecond optical frequency comb

Fig. 5. Calibration of absorption spectrum based on femtosecond optical frequency comb

Fig. 6. FSI system based on absorption spectrum

Fig. 7. Absorption spectrum of HCN

Fig. 8. Absorption spectrum calibration based on optical frequency comb. (a) Absorption signal after resampling; (b) heterodyne signal after resampling; (c) fitting curve of absorption spectrum

Fig. 9. Results of verification experiment. (a) Variations of temperature and OPD with time; (b) distance measurement results before and after calibration

Fig. 10. Schematics of accuracy comparison experiment

Fig. 11. Results of experiment