The formulas for determining the equivalent focal length, principalplanes, focal planes as well as the GRIN lens law are derived.
导出透镜的等效焦距，主面、焦面位置以及高斯成象公式。
2
Starting from the ray path equation, object-image relationships are found and used to determine the equivalent focal length and the principalplanes of tapered GRIN fiber.
本文从光线轨迹方程出发，推导了锥形梯度折射率纤维的物像关系式，并得出了它的等效焦距和主平面位置。
3
This paper advances a direct observational method to determine two principalplanes corresponding with two principal stresses Belng simple and obvious, this method ean be mastered easily.