The core working principle of the Abbe refractometer

An Abbe refractometer is an instrument that determines the concentration of a solution by measuring the refractive index of light in the solution. Its core working principle is to utilize the refraction phenomenon of light in different media.

When light passes from one medium into another medium with a different refractive index, the direction of propagation of the light changes. This phenomenon is called refraction. According to Snell's law, the refraction angle of light is related to the incident angle and the refractive index of the two media.

An Abbe refractometer contains a refractive index measuring cell, usually consisting of a transparent prism. When light enters a prism, it is refracted and then reflected multiple times inside the prism before exiting.

On both sides of the refractive index measurement unit, there are two inlets and two outlets, one for the input and output of pure solvents (such as water), and the other for the input and output of solutions.

When a pure solvent is input into the measurement unit, the light is refracted from the solvent to the prism, then undergoes multiple reflections and finally emerges. At this point, by measuring the incident angle and exit angle of the light, the refractive index of the pure solvent can be determined.

When the solution is input into the measurement unit, the light is refracted from the liquid to the prism, then undergoes multiple reflections and finally emerges. At this time, by measuring the incident angle and exit angle of the light, the refractive index of the solution can be determined.

According to the relationship between the refractive index and the concentration of the solution, the concentration of the solution can be determined by measuring the refractive index of the solution. This measurement is usually made by comparison with a standard solution of known concentration.