Based on the mechanism of near infrared spectral absorption of molecules

an optical fiber sensor for the water content monitoring is studied.Load the semiconductor laser LD with sinusoidal wave

establish a mathematical model of artificial neural network

and use NI data acquisition card and neural network data fitting for the detection of molecules.By using the structure of double optical path it can eliminate noise interference caused by the light intension of light source

and zero shift of photoelectric device.The experimental results indicate that this sensor has steady performance

high sensitivity

good repeatability

and it does not suffer from other gases and impurities interferences.