Fig. 1. Schematic of the under-sampling

Fig. 2. Schematic of positive and negative sampling along the x-axis

Fig. 3. Schematic of undersampling phase validity verification

Fig. 4. Schematic of high-speed and high-precision laser ranging system

Fig. 5. Schematic of a dual-frequency modulated laser source

Fig. 6. Waveform of dual-ruler modulated signal

Fig. 7. Schematic of optical transceiver system

Fig. 8. Flowchart of signal sampling and phase solution circuit

Fig. 9. Flowchart of phase difference solution

Fig. 10. Data of sample board real-time phase detection performance

Fig. 11. Schematic of system velocimetry

Fig. 12. System speed measurement performance with different vibration frequencies and vibration amplitudes（Vibration frequency： 1 Hz， 2 Hz， 5 Hz and 10 Hz from top to bottom； Amplitude： 500， 1 000 and 2 000 from left to right）

Fig. 13. Schematic of system ranging accuracy（45 m）

Fig. 14. Distribution of measurement stability （mean square deviation） at each measurement point within 45 m

Fig. 15. Deviation distribution diagram of ranging accuracy and interferometer accuracy