Refractometers

A refractometer is an optical instrument that measures the refractive index of light in a medium. Refractometry performed with refractometers is one of the common methods for identifying chemical compounds, quantitative and structural analysis, and determining physical and chemical parameters of substances.

A refractometer works by measuring the refractive indices of light in various media. If the density of a substance increases, its refractive index increases proportionally (e.g. when sugar is dissolved in water). The refractometer reads the relative "weight" of the sample compared to distilled water.