Refractive index

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The refractive index (or indices) may be determined using a variety of methods depending on the precision required. If a particle has the same refractive index as the media surrounding it then the edge of the particle will disappear. Consequently, one method employed is to systematically immerse particles in liquids of various refractive indices. Complete sets of graded media may be purchased commercially. For many purposes, including pigment identification, it is sufficient to know if the refractive index is larger or smaller than the mounting media. This procedure is described on the following cards.