Refractive index measurement of liquids using single-shot common-path interferometry

A single-shot common-path interferometric approach is presented for precise measurement of liquid refractive indices in a cuvette. Variations in light divergence caused by liquids with different refractive indices produce measurable phase changes across a fixed field of view. By establishing a quantitative relationship between phase change and refractive index, the technique enables accurate determination of liquid indices. The proposed configuration employs a common-path geometry in which two beams traverse the sample, eliminating the need for separate interferometer arms. This feature simplifies the optical setup and enhances system stability. The feasibility of the proposed method has been verified experimentally by measuring the refractive indices of multiple liquid samples and comparing the results with reliable reference data.