光纤传感测量液体折射率的方法研究

根据菲涅耳公式,推导出了溶液折射率和线偏振光反射率的关系,分别测定不同待测溶液折射率下线偏振光p分量和s分量的反射率,并与理论结果进行比较。实验用阿贝折射仪测定不同浓度下Na_2CO_3溶液的折射率;立足于光纤传感系统,以棱镜为敏感元器件、光为测量媒介,在敏感角入射的情况下,采用光电探测器对偏振光信号进行探测,经光电变换后利用信号调理电路实现信号采集,模数转换后运用单片机实现信息的处理,测定不同浓度溶液的反射率,与理论结果进行比较。结果表明,该方法在实时测量液体折射率的灵敏度、精度方面有较大改善。

Method for measuring the refractive index of liquid by optical fiber sensing

According to the Fresnel formulas, the relationship between the refractive index of solution and the linear polarized reflectance is derived. Reflectance of linearly polarized p and s components at different refractive indices of solution is respectively measured and compared with the theoretical data. The refractive index of Na₂CO₃ solution with different concentrations is measured by an Abbe refractometer. The design is based on the fiber-optic sensing system. Prism is used as a sensitive component and light is a measuring medium. Polarized light signal is detected with a PIN photodiode. After the photoelectric conversion, signal modulation circuit is used to achieve signal collection and signal processing. The reflectance of solution with different concentrations is measured and compared with the theoretical values. The results show that the sensitivity and accuracy in real-time measurement of liquid refractive index are improved.