In Situ Measurement of Deep-Sea Salinity Using Optical Salinometer Based on Michelson Interferometer

Autor: Shuqing Yang, Jie Xu, Lanting Ji, Qingquan Sun, Muzi Zhang, Shanshan Zhao, Chi Wu
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Journal of Marine Science and Engineering, Vol 12, Iss 9, p 1569 (2024)
Druh dokumentu: article
ISSN: 2077-1312
DOI: 10.3390/jmse12091569
Popis: Ocean salinity plays an important role in oceanographic research as one of the fundamental parameters. An optical salinometer based on the Michelson interferometer (MI) suitable for in situ measurement in deep-sea environments is proposed in this work, and it features real-time calibration and multichannel multiplexing using the frequency modulated continuous wave (FMCW) technique. The symmetrical sapphire structure used to withstand deep-sea pressure can not only achieve automatic temperature compensation, but also counteract the changes in optical path length under deep-sea pressure. A model formula suitable for optical salinity demodulation is proposed through the nonlinear least squares fitting method. In vertical profile testing, the optical salinometer demonstrated remarkable tracking performance, achieving an error of less than 0.001 psu. The sensor displays a stable salinity demodulation error within ±0.002 psu during a three-month long-term test at a depth of 4000 m. High stability and resolution make this optical salinometer have broad development prospects in ocean observation.
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