Fig. 1. Absorption and scattering of ray by seawater

Fig. 2. Light source model

Fig. 3. Free space loss model

Fig. 4. Main structural components of the transmitter and physical object

Fig. 5. Main structural components of the receiver and physical objects

Fig. 6. General control of servo

Fig. 7. Motor driver

Fig. 8. Principle block diagram of servo system

Fig. 9. Servo system aiming process

Fig. 10. Experimental environment

Fig. 11. Underwater spot aiming process

Fig. 12. Miss distance of position

Fig. 13. Miss distance of pitching

Fig. 14. Miss distance of position histogram

Fig. 15. Miss distance of pitching histogram

Fig. 16. Block diagram of underwater communication experiment