本文先是利用光线追迹给出了不考虑傍轴近似时轴上点物发射的光线在经透镜折射后最终出射之光线的方程.之后由此方程出发，利用几何画板绘制出了上述情形下透镜像方空间中的出射光场分布图，并对之进行了分析.结果表明，当透镜为凸透镜时，像方空间中起初的一段范围内出射光场的能量主要集中在以一条特殊形状的曲线为母线、以光轴为轴线的旋转曲面所围成的区域中，区域内外有清晰的分界.超出此范围之后，该分界不再清晰，并且会随着到透镜距离的增加而越来越模糊.而在垂直于光轴的各横截面内，随着到透镜距离的增加，出射光场分布先后呈现三种不同的特点.当透镜是凹透镜时，像方出射光场中不存在光强显著超过它处的区域，各横截面内的光能都较为分散.

 The equations of emergent light produced by a point object located on the axis of a len are derived without considering paraxial approximation by using a ray-tracing method. Based on the equations, the distribution diagrams of emergent light field are drawn by using Geometric Sketchpad. The results obtained by analyzing the diagrams show that when the len is convex, the energy of the actual emergent light field in the initial range behind the len is mainly distributed in the zone formed by a rotation surface with a special generatrix and a spin axis which is the optical axis. The border of the zone becomes more and more blurred as the distance from the lens increases. On each cross section perpendicular to the optical axis, the actual emergent light field presents three different characteristics successively with the distance from the len increasing. When the len is concave, there is not a zone where the light intensity is greatly stronger than another zones in the emergent light field, and the energy scatters in every cross section.