Use of light dispersion for monitoring particle purity

The purity evaluation of materials plays an important role in many manufacturing processes. For example, in the pigment industry the desire for high chemical purity is obvious. In this study, a practical spectroscopic method capable of such purity estimation is presented. The method relies on the characteristic light dispersion of materials and it also falls into the range of liquid immersion methods. The method was tested using CaF2 particles with traces of different material as impurities. Our results show that the monitoring of sub ‰-level contamination can be readily achieved. The experimental results are supported by simulations. The light dispersion method can be used for on-site testing purposes where the speed, simplicity and cost of measuring are an issue.