a device for producing plane-polarized light, consisting of two pieces of optically clear calcite or Iceland spar cemented together with Canada balsam in the shape of a prism.
in a polarimeter it is a device which is used to produce the plane polarised light which is used in optical isomerism It is made in such a way that it eliminates one of the rays by Total Internal Reflection i.e, the O-ray is eliminated and only the E-ray is transmitted through the prism.