关键词: Maxwell方程组, 波动光学, 几何光学, 程函方程, 光线（轨迹）方程

Abstract:

The wave equation of light and the differential equation, which describes the amplitude of electric or magnetic field vectors when the ray of light is “moving” in the medium with varying refractive index, were derived by the Maxwell’s equations. The differential equation shows that transformation from “wave” in the view of wave optics to “line” in the view of geometrical optics is a conditional change of physical character. It is also shown that both therepresentations of the concept of wave and method of simple harmonic vibration or concept of light ray and method of geometry,  are opposite but actually are unified, i.e, reaching the same goal of comprehensive understanding on the propagation characteristics of light by different means.

Key words: Maxwell’s equation, wave optics, geometrical optics; eikonal equation, (track) equation of light ray