Development of Seawater Salinity Measurement Technology Based on Optics Method

Abstract

Abstract:

There is a linear corresponding relationship between the refractive index of seawater and the salinity at a certain temperature, so the salinity can be calculated by measuring the seawater’s refractive index indirectly. Several ways to measure the salinity indirectly through the refractive index measurement using optical methods were introduced particularly, including fiber Bragg grating sensor detection, surface plasma wave detection techniques and detection technologies based on geometrical optics method. The salinity sensor structures, measurement precision of every salinity measurement methods were discussed, the factors that affect measurement accuracy were analyzed, as well as the problem in practical applications. Finally, the feasibility of seawater salinity real-time detection by optical technology was prospected.

Key words: ocean optics, optical technology, salinity measurement, refractive index

CLC Number:

TN253
TP212

SONG Zhi-Jiang, NI Jia-Sheng, WANG Chang, CHEN Shi-Zhe, XU Jia-Feng. Development of Seawater Salinity Measurement Technology Based on Optics Method[J]. Journal of Atmospheric and Environmental Optics, 2010, 5(4): 247-254.

References

[1] Min Xueyi, Chen Guohua, Han Wuying, et al. Relationships between electrical conductivity, chlorinity and density of coastal waters of China [J]. Oceanologia & Limnologia Sinica, 1984, 15(1): 82-90(in Chinese).
闵学颐, 陈国华, 韩舞鹰, 等. 中国近海海水电导率、氯度和密度的相互关系 [J]. 海洋与湖沼, 1984, 15(1): 82-90.
[2] Li Qingxia, Zhang Jing, Guo Wei, et al. Overview on ocean salinity remote sensing by microwave radiometer [J]. Ocean Technology, 2007, 26(3): 58-63(in Chinese).
李青侠, 张靖, 郭伟, 等. 微波辐射计遥感海水盐度的研究进展 [J]. 海洋技术, 2007, 26(3): 58-63.
[3] Ma Yong, Liang Kun, Lin Hong, et al. Study on simultaneous measurement of temperature and salinity based on Brillouin scattering [J]. Acta Optica Sinica, 2008, 28(8): 1508-1512(in Chinese). 马泳, 梁琨, 林宏, 等. 基于布里渊后向散射的海水温度与盐度同步测量研究 [J]. 光学学报, 2008, 28(8): 1508-1512.
[4] Noto V D, Mecozzi M. Determination of seawater salinity by ultraviolet spectroscopic measurements [J]. Applied Spectroscopy, 1997, 51(9): 1294-1302.
[5] Martelli C, Canning J, Kristensen M, et al. Refractive index measurement within a photonic critical fiber based on short wavelength diffraction [J]. Sensors, 2007, 7(11): 2492-2498.
[6] Quan Xiaohong, Fry E S. Empirical equation for the index of refraction of seawater [J]. Applied Optics, 1995, 34(18): 3477-3480.
[7] Pereira D A, Frazao O, Santos J L. Fiber Bragg grating sensing system for simultaneous measurement of salinity and temperature [J]. Optical Engineering, 2004, 43(2): 299-304.
[8] Wang Cheng, Wang Zhengping, Zhang Guosheng, et al. A method for simultaneous measurement of liquid refractive index and temperature [J]. Optics & Optoelectronic technology, 2006, 4(5): 52-54(in Chinese).
王成, 王政平, 张国生, 等. 一种同时测量液体折射率和温度的方法 [J]. 光学与光电技术, 2006, 4(5): 52-54.
[9] Zhao Qingchun. Research advance of polymer hydrogels [J]. Polymer Materials Science and Engineering, 2005, 21(2): 28-31(in Chinese).
赵青春. 聚合物水凝胶研究进展 [J]. 高分子材料科学与工程, 2005, 21(2): 28-31.
[10] Han Yuewen, Li Xiaogang, Chen Rong. An optical fiber sensor for salinity measurement [J]. Acta Laser Biology Sinica, 2005, 14(4): 308-310(in Chinese).
韩悦文, 李小刚, 陈荣. 一种用于盐度测量的光纤传感器 [J]. 激光生物学报, 2005, 14(4): 308-310.
[11] Cong Jun, Zhang Xianmin, Chen Kangsheng, et al. Fiber optic Bragg grating sensor based on hydro gels for measuring salinity [J]. Sensors and Actuators B: Chemical, 2002, 87(3): 487-490. [12]Kretschmann E, Raether H. Radiative decay of nonradiative surface plasmons excited by light [J]. Zeitschrift Fuer Naturforschung Section AA, Journal of Physical Sciences, 1968, 23: 2135-2136. [13] Wu Yingcai, Yuan Yifang. Research of a novel principle on seawater salinity measurement based on refractive index change [J]. Acta Optica Sinica, 2005, 25(2): 199-202(in Chinese).
吴英才, 袁一方. 基于折射率变化的一种新型盐度测量原理研究 [J]. 光学学报, 2005, 25(2): 199-202.
[14] Zhang Jiangtao, Gu Zheng. Principle and study progress of fiber optic chemical sensor based on surface Plasmon resonance [J]. Laser & Optoelectronics progress, 2008, 45(10):24-31(in Chinese).
张江涛, 顾铮. 光纤表面等离子体共振光化学传感器的原理及进展 [J]. 激光与光电子学进展, 2008, 45(10): 24-31.
[15] Esteban O, Cruz-Navarrete M, Gonzalez-Cano A, et al. Measurement of the degree of salinity of water with a fiber-optic sensor [J]. Applied Optics, 1999, 38(25): 5267-5271.
[16] Grunwald B, Holst G A. SPR fiber optic microsensor system and applications [C]. Proceedings of SPIE, 2002, 4578: 96-107.
[17] Zhao Yong, Zhang Bo, Liao Yanbiao, et al. Salinity measurement based on position sensitive detector and optical technology [J]. Acta Optica Sinica, 2003, 23(11): 1379-1383(in Chinese).
赵勇, 张博, 廖延彪, 等. 基于位置敏感器件的光学法盐度检测技术研究 [J]. 光学学报, 2003, 23(11): 1379-1383.
[18] Brice B A, Halwer M. A differential refractometer [J]. Journal of Optical Society American, 1951, 41(6): 1033-1037.
[19] Zhao Yong, Liao Yanbiao. Novel optical fiber sensor for simultaneous undersea temperature and salinity measurement [J]. Acta Optica Sinica, 2002, 22(10):1241-1244(in Chinese).
赵勇, 廖延彪. 海水盐度和温度实时检测的新型光纤传感器研究 [J]. 光学学报, 2002, 22(10): 1241-1244.