利用光纤法布里-珀罗(F-P)干涉仪透射光谱的中心波长与其干涉腔内介质折射率之间的线性关系,提出一种实现液体/气体折射率精确测量的方法,消除了光源强度波动对测量结果的影响和量化误差.开发出一套实验系统,采用可调光滤波器对传感信号进行采集.利用一组不同浓度的酒精溶液对折射率与干涉波长之间的关系进行了拟合,拟合误差小于0.00005.对蒸馏水和丙酮折射率的实际测量实验误差小于0.0001.

A technique for accurate measurement of the refractive indexes of liquid and gas was proposed. The approach, based on Fabry Perot (F P) interferometer and using the central wavelength of transmission spectrum to elicit the measurand, essentially eliminates the errors aroused from light source fluctuation. Such a system was developed. The optical signal was transmitted through fibers, and a tunable optical filter is used to collect the sensing data. Using the test data of refractive indexes of a set of alcohol solution with different concentrations, the analytical relation between refractive index and central wavelength of transmission spectrum was educed with least squares linear regression method, the regression error is less than 0 00005. Refractive indexes of distilled water and acetone were measured respectively; the measuring error is no more than 0 0001.