It’s interesting that the focusing for Gaussian beam with a left-handed material coincide with imaging formalism of geometrical optics and do not exist focal shift.

同时,我们还发现像方高斯光束束腰的位置和几何光学预言的成像位置是完全一致的,即平板左手材料透镜对傍轴光束的聚焦不存在一般透镜聚焦的焦移现象。

Lie algebraic theory is a technique that is applied in studying geometrical optics from a new point of view and it is a complementary method compared with those traditional methods of studying optical systems.

李代数理论是从一个新的角度解决几何光学的问题，是传统像差理论的有效补充。