双折射晶体中的光程和费马原理

Optical Path in Birefringent Crystal and Fermat's Principle

通过严谨定义双折射晶体中光程的概念,并通过费马原理将该定义应用到晶体界面中的光双折射过程得出折射角和入射角之间的关系,发现双折射过程中折射角和入射角之间的关系不仅依赖于晶体的主折射率,还与晶体的方向有关.通过应用晶体中的斯涅耳定律以及波前法线方向与光传播方向之间的关系,验证了该结果的正确性.

In this paper,a definition for the optical path in birefringent crystals propose is proposed.And the definition is applied to light refraction in a crystal-crystal interface by means of Fermat’s principle and the relationship between the angles of incidence and refraction is obtained.It is found that this relation not only depends on the principal refractive indices of birefringent crystals,but also highly depends on the crystal orientation.The conclusion is also confirmed by applying Snell’s law generalized for crystals and the relation between the direction normal to the wave front and the ray.