A fiber—Optic differential pressure sensor based on microchannels fabricated laser

A novel fiber-optic differential pressure sensor is designed and theoretically analyzed in this paper. Symmetrical structure between standard cavity and measured cavity is adopted in this sensor, the electro-optic Q-switched laser is used to produce mixed light by extra cavity double frequency,and this mixed light induce plasma to process the μm microchannels which position the emergent fibre and incident fibre, the output signal of the cavities is processed by the signal processing section. The relations between the pressure in cavity and film deformation or the output light intensity are theoretical analyzed, then the mathematical models are established. The relations of Iout/Iin and film distance d, pressure of detection cavity P, pressure of standard cavity P are obtained through a lot of experiments. The results indicated that with the pressure of measured cavity increasing, the value of Iout/Iin decreases, and the Iout/Iin value of standard cavity tends to stable. Through calculating the two values, the sensor can achieve the active measurement of relatively pressure between standard and measured cavity.