基于低相干光干涉的液体折射率测量

摘要

液体折射率是液体一个重要指标,介质中折射率的变化会影响光程,提出一种用低相干光干涉测量光程变化,进而测得折射率的方法.通过调节两束低相干光使它们之间的光程差在相干长度之内,将被测液体放入一束光路中,根据光电探测器得到的干涉信号可求得相应的光程变化量,进而得到待测液体的折射率.利用低相干光干涉测量折射率的方法,其测量和计算过程方便快捷,受外界限制因素小,在810 nm波长下,对折射率的测量精度可以达到10-4量级以上,是测量各种液体折射率的有效方法.%Refractive index is an important physical parameter of the liquid.The changes of the medium refractive index will affect the optical path.The optical path changes can be measured with an optical low-coherence interferometry.When the optical path difference of the two low-coherence lights is close to equal,the optical low-coherence interference is generated.A photodetector is used to detect the interference signal,and the optical path difference can be measured.Then the refractive index of liquid can be calculated from the measured optical path difference.This method is convenient and fast for the measurement of liquid refractive index.Refractive index measurement precision can reach 10-4 orders of magnitude at 810 nm.