THE BASIC PRINCIPLES OF BIREFRINGENT CRYSTAL

各向异性透明晶体如方解石、石英等的折射率，是其固有的特性，称为永久双折射。The lessen section in the Michel-Levy chart (x-axis) marks the orders of retardation in multiples of around 550 nanometers. The world concerning zero and 550 nanometers is named the very first purchase of polarization colours, along with t