Liquid refraction and dispersion measurements by multiple-beam white-light Newton's fringes

Multiple-beam white-light Newton's fringes in transmission are produced in a Newton's interferometer containing a liquid sample and followed with a grating spectrograph. An equation describing the shape of the formed interference fringes is derived. A simple procedure is introduced for analyzing the resulting interference fringes. This enables the determination of both: the liquid refractive index, the fringe order of interference and the thickness at the point of contact. Errors of the measured liquid refractive index are discussed. The method is used for measuring the refraction and dispersion of glycerin, dimethylformamide (DMF) and water across the visible spectrum. The method is a single-shot, static, material-economic and low-cost interferometric one.