Dispersion-equation coefficients for the refractive index and birefringence of calcite and quartz crystals

The refractive index, birefringence and their dispersions are analyzed accurately in a physically meaningful model of a dispersion equation having only five coefficients for the calcite and quartz crystals. This dispersion equation is based on the average electronic absorption gap in the UV region and the effective lattice resonance absorption gap in the IR region. The five coefficients of the dispersion equation are different for each fundamental parameters. The dispersion equation for the birefringence leads to represent a standardized equation describing the birefringence of all optical materials.