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Proceedings Paper

Optimal design of optical refractometer for seawater salinity measurement
Author(s): Xia Cen; Juan Su; Guoqiang Li; Wei Wei; Xiaoxue Bai; Chi Wu
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Paper Abstract

Salinity of seawater is one of the most important ocean parameters. Salinity of seawater is mainly obtained by conductivity measurement using CTD (Conductivity-Temperature-Depth). Conversion accuracy between conductivity and salinity relies on the assumption that components of seawater are fixed, as well as high accuracy and synchronism measurements of conductivity, temperature and pressure. The study of seawater salinity based on the V-block optical refractive index method provides a total different principle for salinity measurement. Achieving high resolution seawater optical refractive index measurements could help to study factors affecting the accuracy of salinity measurement. In this paper, the various instrument parameters that affect the accuracy of seawater refractive index measurement are analyzed and the optical refractometer is optimized based on the components on the shelf. This paper systematically analyzed the resolution and tolerance of refractive index measurement on the parameters of V-block refractometer, such as incident angle, external environment and prism refractive index, etc. The optical refractometer with an air film layer on both sides of the V-block was proposed for seawater salinity measurement. With such an optimization, the measurement accuracy is further improved and the tolerance is increased. The theoretical resolution to the seawater refractive index and salinity are 1.8×10-6 and 0.01‰, respectively. Experimentally, we have achieved 3.9×10-6 and 0.021‰ respectively, and a good linearity. The difference between theoretical and experimental results are analyzed.

Paper Details

Date Published: 31 January 2020
PDF: 8 pages
Proc. SPIE 11427, Second Target Recognition and Artificial Intelligence Summit Forum, 1142748 (31 January 2020);
Show Author Affiliations
Xia Cen, Shandong Univ. (China)
Juan Su, Shandong Univ. (China)
Guoqiang Li, Shandong Univ. (China)
Wei Wei, Shandong Univ. (China)
Xiaoxue Bai, Shandong Univ. (China)
Chi Wu, Shandong Univ. (China)

Published in SPIE Proceedings Vol. 11427:
Second Target Recognition and Artificial Intelligence Summit Forum
Tianran Wang; Tianyou Chai; Huitao Fan; Qifeng Yu, Editor(s)

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