The Research On The Measurement Technology Of Salinity By Fiber Sensor

Some classic definitions and their measurement and the calculating formula of the salinity are introduced, also with their variation. The importance of the salinity measurement is stated from the angles of its application in agriculture exploration antisepsis ecology and environment protecting weather observation military application new energy developing and so on.3 modern ways-diffraction index measuring, electric conductivity, and density measuring for salinity measuring are described simply, which are based on optical electrical and dynamical characters of the solution.2 ways of fibre sensing-de-cladding fibre sensing and fiber Bragg grating sensing are presented with their principles, manufacture, operation, effects, merits and demerits.New means by fibre sensor is offered for the salinity measurement, based on the gel's sensitivity to the salinity, leading to the correspondence between the light loss and salinity. A simple sensor is made from the intellect gel~ PDA-C12, which is insensitive to temperature, SM fibre and MM fibre, the correspondence between optical loss and concentration is measured, the results of both sensors are compared; the response time of sensors by various shapes of the gel is also compared, it proved the influence of the shape factor to the ion osmosis and stress balance in the gel. The sensitivity of each point is calculated by difference method. The error source is analyzed and the solution is discussed.The experimental data is fitted by several ways, and the program written in MATLAB is run, the best one of the result is found out, after compare.The primary signal process system is designed by EDA tools, including main modules and circuits; the data process algorithm is designed based on the conclusion above.The excellencies and imperfections of this method is canvassed contrasting others, its adaptability and practical directions are studied.