Refractometers

Based on the principle that the speed of light changes when it passes through materials based on their densities, a refractometer characterizes fluids based on their obtained refractive indices. The relative refractive index is calculated by the speed of light in vacuum, which has a refractive index of 1, divided by the speed of light through a substance. The refractive index is a constant physical property of a pure compound, however, when in the presence of impurities, this refractive index will change. Measurements obtained by refractometers rely on the wavelength of the light and the temperature of the solution, therefore, a wavelength of 589.3 nm and a temperature of 20C are used in standard refractometers.