Application Of High-Precision Fiber Fabry-Perot Interferometer On Liquid Refractive Index Sensor Measurement

As a transmission medium in measurement system, fiber has various advantages. As a result, optical fiber sensors, which have burgeoned in the pass twenty years, have become a research focus in the sensor field, and have been extensively applied in many fields such as process control, biochemistry, navigation, structure detection, non-contact measurement and so on.Keeping to the point, the main points of this thesis can be classified as follows:1. Conventional sensors have been introduced, so have the differences compared to optical fiber sensors, and then the feasibilities and advantages of optical fiber sensor have been illustrated. As a kind of optical fiber sensor, fiber Fabry-Perot interference sensor, because of its high-sensitivity and high-precision, has been applied abroad in physical measurement: temperature, stress, displacement, acceleration, refractive index, etc.2. The optical measurement of liquid refractive index has been reviewed, according to the point that the interference stripes'change can describe the refractive index micro-change in the Fabry-Perot cavity when the laser beam goes through the Fabry-Perot interferometer, we have designed a liquid refractive index measurement system, it consists of a single mode fiber as the transmission medium, a Fabry-Perot interferometer as the sensor apparatus and a split-type area CCD video as the video receiver.3. Two different Fabry-Perot cavities have been adopted: plane mirror cavity and confocal concave spherical mirror cavity. First, we got the relationship between refractive index and interference stripe in the two cavity structures after theoretical analysis, then, carried out experimental research in the measurement system with the two different cavities respectively, and 10-5 magnitude change in refractive index has been detected in the two cavities, the result is satisfied.