Refractive Index Analyzers

A refractometer determines the concentration of a solution by measuring the optical refractive index. As the concentration of dissolved solids in the process fluid changes, the refractive index changes. As a result, the position of the critical angle will change. An increasing concentration of dissolved solids increases the amount of refraction and reduces the amount of reflection. Temperature is a very important parameter in order to properly relate concentration to refractive index using a process refractometer. The accuracy required by an application is a function of the relationship between refractive index and concentration of the process fluid. The measurement accuracy of refractive index is a function of the how the instrument makes its measurement. Process conditions such as lower temperature and the feed ratio can be changed to compensate for these changes. The feedback and response time is reduced from hours via laboratory measurements to minutes via on-line process analyzers.