Instrumentation for highly accurate index measurement of liquid

The index of refraction is one important optical property of materials. It also provides information to analyze liquids or mixed solutions, such as chemicals, foodstuffs, drinks, and pharmaceuticals. In this work, we would like to introduce a creative but simple method to measure the index of liquid. The measurement accuracy was high, with an error under 5×10^-5 for DI water. This method presented similar merits as minimum deviation method inherently. However, the simplicities in measurement process and experimental parameters showed great potential for accurate index measurement applications. Most of the design and developing works of this measurement system was performed by undergraduate students from Physics Department and Department of Optics and Photonics. The hardware integration and the data-acquire automation provided practical learning opportunities for the subjects about optics, electronics, programming, and data analysis. And, the measurement results can also provide further insights about the temperature or concentration related index variation of liquid for the students.