Fig. 1. Schematic of seawater sound velocity measurement

Fig. 2. Principle of pulse acousto-optic effect. (a) Light intensity detection diagram without acousto-optic effect; (b) light intensity detection diagram with acousto-optic effect

Fig. 3. Diagram of light intensity variation

Fig. 4. Abrupt light intensity caused by acousto-optic effect

Fig. 5. Schematic of sound velocity measurement in pure water and seawater

Fig. 6. Spectrum of light source

Fig. 7. Frequency spectrum of 1 MHz signal

Fig. 8. Long-time measurement results of 1 MHz signal

Fig. 9. Allan variance of 1 MHz signal

Fig. 10. Phase of beat frequency

Fig. 11. Abruption of reference light (A) and measured light (B) caused by acousto-optic effect

Fig. 12. Experimental results of pure water

Fig. 13. Difference between VMini and Ve at different time in pure water

Fig. 14. Experimental results of seawater

Fig. 15. Difference of VMini and Ve at different time in seawater