In this study, an improved sensor for measuring the refractive index of seawater is proposed. The sensor determines the refractive index based on the displacement of a laser spot detected by a photodiode array displacement sensor. It features a simple and low-cost design, making it well-suited for detecting small variations in the refractive index of seawater. Measuring seawater salinity has long been a critical issue in marine science, particularly in fields such as aquaculture and underwater acoustics. In aquaculture, salinity directly affects the living conditions of aquatic organisms, while in acoustic applications, it influences the propagation speed of sound in seawater. Therefore, precise salinity measurement is essential for both scientific research and practical marine applications.
Hsieh et al. (Mon,) studied this question.