结合光学原理，利用全反射，设计测量透明液体浓度的实验装置.由亚克力板容器盛装待测液体，研究激光在液体中发生全反射时的光路参数，通过测量两个长度尺寸，计算得到透明液体的折射率，基于透明液体折射率与浓度之间的线性关系，进而得到其浓度.蔗糖溶液和NaCl溶液的测量数据结果表明，折射率的相对误差在0.4％以内，浓度的绝对误差在0.7%以内.该实验装置具有结构简单、操作简便、测量精度高、成本低廉、现象明显等优点.

An experimental device for measuring the concentration of transparent liquids is designed based on optical principles and total reflection. The liquid to be measured is contained in an acrylic plate container, which is used to study the optical path parameters when total reflection generates in the liquid. The refractive index of the transparent liquid is calculated by measuring two length parameters. Its concentration is obtained by using linear relationship between the refractive index and the concentration of transparent liquid. The measured data of sucrose solution and NaCl solution show that the relative error of refractive index is within 0.4%, and the absolute error of concentration is within 0.7%. This experimental device has the advantages of simple structure, simple operation, high measurement accuracy, low cost and obvious phenomenon.