Design And Research Of The Reflective Intensity Modulated Fiber Optic Acoustic Pressure Sensor

Fiber optic acoustic pressure sensor with small, simple structure, high sensitivity, anti-electromagnetic interference, and other characteristics, mainly used in the environment in which the traditional electro-acoustic microphone can not be used, such as the environment with strong electromagnetic interference(CT Room) and the flammable explosive environment (oil well). Many researchers have conducted in-depth study, but some of the parameters is not very satisfactory, such as sensitivity and so on. Particularly, more work should be completed on the practical aspect.This paper briefly reviewed the research history of fiber optic acoustic pressure sensor, after made reference to previous research experience and research findings. The paper made a detailed analysis of geometrical optics model, photometry model, and Gaussian optics model on mathematical model of intensity modulation. And on this basis, associated with the mathematical simulation and testing, the paper analyzed the impact of light microphone sensitivity of various factors. Based on a detailed analysis of the factors, the paper pointed that sensitivity of the traditional optical microphone system was low because of using optical fiber as the emitter. The beam divergence of this system was very high, so that the mode field radius spot was very big. That is the real reason why this system had lower sensitivity. Based on this analysis, the paper pointed out a new way of using a kind of optical fiber collimator instead of optical fiber and reshaping the light with collimator to ensure that the spot had proper radius. In this paper, experiments and mathematical simulation proved the feasibility of such a design. Author also analyzed the factors which can impact the sensitivity of such improved system in order to further optimize the system. In addition, the paper established a mechanical model of membrane and analyzed the factors which can impact the sensitivity of the membrane in order to provide design of the membrane with introduction.