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提出了一种测量液体折射率的光纤液体分析仪。利用液体表面张力的作用,在光纤探头端形成一个液滴。该液滴的作用相当于一个平凸透镜,发射光纤出射的光经液滴表面折射、未扰液面的反射和液滴表面的再次折射后进入接收光纤。根据菲涅耳公式,光线在各个界面的透射系数和反射系数与液体的折射率有关,且对于不同的液体,光线的传输路径不同。基于球面折射成像和反射式强度调制原理,分析了光线的传输路径,并建立了接收光纤接收到的光强与液体折射率的关系模型。对不同浓度的NaCl溶液进行了测量,实验结果符合理论预期,表明该方法可以用于液体折射率的测量。
An optical fiber liquid analyzer is proposed to measure the refractive index of liquid. Using the effect of liquid surface tension, a droplet is formed at the tip of the fiber optic probe. The droplet acts as a plano-convex lens. The light emitted from the emitting fiber is refracted by the droplet surface, reflected by the un-disturbed liquid surface, and re-refracted by the droplet surface before entering the receiving fiber. According to the Fresnel formula, the transmission and reflection coefficients of light at various interfaces are related to the refractive index of the liquid, and the transmission paths of light are different for different liquids. Based on the principle of spherical refraction imaging and reflection intensity modulation, the transmission path of light is analyzed, and the relationship between the received light intensity and the refractive index of liquid is established. Different concentrations of NaCl solution were measured, the experimental results in line with the theoretical expectation, indicating that the method can be used for liquid refractive index measurement.