optical birefringence demonstrated using a text using a natural double spar calcite crystal

polarization dispersion axis optical circular birefringence polarized rotation interference calcite crystal education message geometrical polarizer scientific vector science illustration refraction double light natural transparent mineral calcium structure material optics crystalline carbonate cristal anisotropic demonstration shadows property refractive index birefringent birefractive optic wave propagation calcit caco3 trigonal biaxial materials dielectric text