Fig. 1. Schematic diagram of laser scattering from sea surface

Fig. 2. Diagram of discretization of S_xy

Fig. 3. Rough surface model in different sea state. (a) Three-level sea state; (b) Four-level sea state

Fig. 4. The BSC of laser from different rough surface at incident angle \begin{document}$ {\theta _{i1}} = {20^ \circ } $\end{document}. (a) Surface A; (b) Surface B

Fig. 5. The BSC of laser from different rough surface at incident angle \begin{document}$ {\theta _{i1}} = {60^ \circ } $\end{document}. (a) Surface A; (b) Surface B

Fig. 6. The BSC at different incident angles. (a) \begin{document}$ {\theta _{i1}} = {20^ \circ } $\end{document}; (b) \begin{document}$ {\theta _{i1}} = {60^ \circ } $\end{document}

Fig. 7. The transmittance at different incident angles

Fig. 8. Schematic diagram of the simulated test system

Fig. 9. Indoor simulation test system

Fig. 10. Optical system

Fig. 11. Test tank

Fig. 12. CO₂ laser

Fig. 13. Schematic diagram of the vaporized laser acoustic threshold test system. (a) Before laser incident; (b) After laser incident

Fig. 14. Acoustic pulse signal

Fig. 15. Acoustic pulse spectrogram

Fig. 16. Area of light spot perpendicular to incident water surface. (a) Light spot before the divergence angle compression; (b) Light spot after the divergence angle compression