Refractive index

Choose this service if you are working on a new product and also if you want us to perform the laser diffraction analysis for accurate measurement of particle size and distribution. 

Determination of the refractive index for accurate calculation of particle size and distribution – especially for small particles.  

  • The calculation model based on Mie theory uses a refractive index to calculate the accurate particle size distribution from the light diffraction data.   
  • As one of few companies globally, Particle Analytical offers a determination of the refractive index of your compound.  

The refractive index (or index of refraction) n of a substance (optical medium) is a number that describes how light, or any other radiation, propagates through that medium. The absorption part describes the amount of light being absorbed by the particle. 

In order to make accurate particle size and distribution determination, especially of small particle sizes, it is necessary to know the refractive index of the compound.  The refractive index is determined by laser diffraction and is not as such a separate method. 

For laser diffraction two optical models are generally used, Fraunhofer and MIE: 


Based on the Mie theory it is necessary to know the value of refractive index and absorption. 

Be aware that using default values might lead to the wrong interpretation of the results.  

Consult our Experts


Dr. Changyong Lu
QC Chemist

Dr. Anna Shevchenko
Principal Scientist


Atsavapranee P, Gharib M (1997) Structures in stratified plane mixing layers and the effects of cross-shear. J Fluid Mech 342(1):53–86 

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