Water Temperature and Salinity Measurement Using Frequency Comb

Water temperature and salinity are key parameters in many fields such as industry, forestry and agriculture. In this paper, we, theoretically and experimentally, demonstrate a method which is capable of water temperature and salinity measurement based on a laser frequency comb at 518 nm. We have developed a simple Michelson interferometer system. By scanning a mirror on a precision displacement platform, a pair of cross-correlation patterns can be obtained. The real-time optical distance information from these cross-correlation patterns can be used to calculate the optical distance difference changes. Temperature and salinity can be measured via these changes, aided by the empirical formulas. Compared with the reference values, our results show the differences of below 0.12 °C for temperature measurements, and 0.06‰ for salinity measurements. The obtained results indicate that our method can offer a powerful scheme for future temperature and salinity measurement.