Refractometers are utilized to determine the composition and purity of substances quantitatively through the measurement of the refractive index of light. The most common types of refractometer are Abbe refractometer, Digital handheld refractometer, Digital benchtop refractometer and Handheld manual refractometer. The refractive index is a value obtained by dividing the velocity (distance traveled divided by the time required to travel that distance) of light in a vacuum (empty space) to the velocity of light in a medium (container). The refractive index is expressed quantitatively by using an equation derived from Snell's Law. The refractometer's mechanism of action is derived from the Refraction of Light principle--in other words, the bending of a light's wave when it changes speed upon entering a transparent object.

A refractometer is a significant tool in measuring the sugar content of foods. It is done by using the Brix scale, which is the measure of soluble sugar in water at a particular temperature. For instance, a sample with a refractive index value of 1.3403 is equal to 5.0 percent sucrose in the Brix scale. Researchers analyze and determine the amount of acids, fats and salt are present in a substance by using a refractometer. For instance, liquids such as alcohols are analyzed in industrial laboratories to detect the presence of dirt and other contaminants. There are many uses for refractometers, including the food industry, automotive, and many industrial, as well.