Method for measuring seawater salinity

Abstract

The invention discloses a method for measuring seawater salinity. The method includes that a narrowband light source, an optical fiber F-P refractive index sensor, an optical fiber Bragg grating temperature sensor, a data collection card and a control unit are utilized to set up a measuring system, a light signal output by the narrowband light source is split into reference light and sensing lightby a first optical coupler, the reference light is fed into the data collection card sequentially through a F-P etalon and a photoelectric detector, the sensing light is split into two branches by asecond coupler, the two branches are emitted into the refractive index sensor and the grating temperature sensor respectively, reflected-back light is fed into the data collection card through the photoelectric detector, and the control unit analyzes reflection spectra to acquire a salinity value of measured seawater. The optical fiber sensors are utilized to set up the measuring system, and the system is small in size and high in accuracy and can run reliably in severe environment conditions, so that long-time real-time monitoring of seawater salinity in complicated and changeable marine environment is realized. In addition, the measuring system has the advantages of simple structure, low cost and convenience in operation.

Description

technical field [0001] The invention relates to an online detection method for measuring seawater salinity by using an optical fiber F-P refractive index sensor, belonging to the field of measurement technology. Background technique [0002] Salinity is an important characteristic of seawater and an important parameter for studying the physical and chemical properties of seawater and related processes. Real-time online detection of seawater salinity is of great significance in the fields of marine environmental protection and ecological governance, marine science, marine engineering, and military defense. In recent years, the detection technology of seawater salinity has received extensive attention. The existing seawater salinity measurement methods include electrical conductivity method, microwave space remote sensing method, surface plasmon resonance method, Brillouin scattering method, Raman spectroscopy and so on. The conductivity method has high stability and resolut...

AI Technical Summary

Problems solved by technology

The conductivity method has high stability and resolution, and can be continuously detected on site, but the electrodes are extremely vulnerable to water pollution and electromagnetic interference, which affects the accuracy of measurement; microwave remote sensing technology uses microwave radiometers to measure the brightness and temperature of seawater, and through inversion get seawater salinity

This method is suitable for large-area measurement of seawater salinity, and has the advantage of all-weather, but due to the weak microwave penetration ability, this method is limited to the salinity inversion of seawater surface, and the measurement accuracy is not high

Surface plasmon resonance method, Brillouin scattering method, Raman spectroscopy and other measurement methods use complex structures and bulky instruments, which are difficult to be used for on-site real-time detection of seawater salinity

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