Abstract: In this paper, a new method for measuring the refractive index of liquids based on the principle of total internal reflection is proposed. Through the combination of numerical simulation and experimental verification, the optimal design and performance of the refractive index measurement device are realized and verified. Based on MATLAB simulations, the influence of liquid groove top angle parameters on the refractive index measurement range is systematically analyzed, and a control mechanism for key parameters is established. Furthermore, an experimental device has been developed, integrating a coaxial rotating dual-dial reading system with a smartphones optical sensor, based on these simulation results. The adjustable platform design significantly enhances the systems adaptability and precision. Experimental verification demonstrates that the relative error in the refractive index measurement of deionized water and NaCl solutions of different concentrations is well below 5.00%, confirming the reliability of the method and the accuracy of the device. This provides a new visualization and precision scheme for the measurement of the refractive index of transparent liquids.

Key words: total reflection, combination of virtual and real, liquid refractive index, dual dial, MATLAB