液体的折射率是一个重要的物理参数,在外界一定的条件下,掌握液体折射率及其变化,则可以了解其纯度、浓度等参数及品质。提出一种用低相干光外差干涉方法测量反复使用食用油的折射率,进而鉴别油的品质。实验以改进的迈克尔逊干涉仪为基础,将样品油放入测量臂光路中,当两束分别来自测量臂与参考臂的低相干光的光程接近相等时,会出现光外差干涉现象。利用光电探测器得到此干涉信号,根据前后相应的光程变化量,进而得到待测样品的折射率。食用油经反复加热1、2、3、5、7次后,葵花油的折射率分别为1.469 5、1.469 7、1.470 1、1.470 7、1.471 3,玉米油的折射率分别为1.468 8、1.469 1、1.469 4、1.470 1、1.471 1。结果表明,该方法可以准确测量出不同加热次数食用油的不同折射率,测量稳定性较高,能快捷、有效地鉴别反复使用的食用油品质。

The optical refractive index of the liquid is an important physical parameter.Under certain external condition,mastering the physical refractive index and its changes well is helpful to understand the liquid purity,concentration,other parameters and quality.An optical low coherence heterodyne interferometry is proposed to measure the refractive index of repeated use of edible oil and then used to identify the quality of the oil.The experiment is based on the improved Michelson interferometer.The sample oil is put into the optical path of measuring arm.When the optical path length of two beams from the measuring arm and the reference arm is equal,the optical heterodyne interference phenomenon can be generated.A photo detector is used to detect the interference signal according to the corresponding optical path variation,and then the refractive index of the sample can be calculated.Edible oil was repeatedly heated 1,2,3,5,7 times.The refractive indices of sunflower oil were 1.469 5,1.469 7,1.470 1,1.470 7,1.471 3 respectively,and the refractive indexes of corn oil were 1.468 8,1.469 1,1.469 4,1.470 1,1.471 1 respectively.The results show that this method can accurately measure the different refractive index of edible oil with different heating times.It has high stability and can quickly and effectively identify the repeated use of edible oil quality.