Fig. 1. Principle of acquisition

Fig. 2. Principle of DWS technique^[19]

Fig. 3. Diagram of laser link construction on-ground experiment system

Fig. 4. Schematic diagram of electronic system

Fig. 5. Scan curve

Fig. 6. Result verification of spot centroid location. (a) Original image; (b) calculation result of MATLAB; (c) calculation result of ZYNQ simulation

Fig. 7. Test result of closed-loop control

Fig. 8. Process control

Fig. 9. Experimental setup. (a) Single platform; (b) two platforms placed on both ends of marble platform

Fig. 10. Calibration of conversion coefficients. (a) Calibration of angle-position conversion coefficient; (b) calibration of angle-angle conversion coefficient

Fig. 11. Whole-process diagram

Fig. 12. Experimental results from different starting points. (a) P1 starting at (200, 200) and P2 starting at (-200, -500); (b) P1 starting at (-200, -200) and P2 starting at (300, 300)

Fig. 13. Background noise. (a) Time domain; (b) frequency domain