Liquid concentration measurement based on the optoacoustic effect and fiber Bragg grating sensor technology

An experimental system for liquid concentration measurement was set up based on the optoacoustic effect and a fiber Bragg grating (FBG) underwater sound sensor. Measurement theory and each element of the experimental setup are introduced. The light beam was injected into the liquid by a fiber bundle with a graded-refractive-index lens at the end. A matched FBG was used to demodulate the wavelength shift signals from the sensing FBG. Preliminary experimental results of sodium carbonate liquid concentration measurement were obtained, which verifies the feasibility of the method.