文章采用了一种较为简便、自然的推理方法，推导出物点经平行介质界面二次折射成像的虚像点位置，发现了所谓的“物点经多层平行介质界面折射成像的叠加法则”.文章对几种特殊情形下的像点坐标进行了讨论: 分析和解释了游泳池中泳女的“身首分离”折射现象; 分析出空气中物体经玻璃砖的成像特点，指出人们通常使用薄玻璃窗户的光学依据; 对空气中的物点经折射率线性变化介质的折射成像进行了详细的研究，指出物点经折射率均匀变化介质的成像位置与经平均折射率的等厚介质，除 80° ～90°的大视角情形外几乎一致.文章中的推理方法和结论或可为相关内容的教学、科研提供参考.

In this paper，a simple and natural reasoning method is used to deduce the virtual image

point posi- tion of the secondary refraction imaging of object point refracting through the

parallel medium interface，and the so- called “superposition rule of refraction imaging of object

points through multi-layer parallel medium interface”is found. This paper discusses the

coordinates of image points in several special cases: the refraction phenomenon of “body

head separation”of the female swimmer in swimming pool is analyzed and explained; the imaging

character- istics of objects in the air through glass blocks are analyzed，the optical basis

for people to usually use thin glass windows is pointed out; the refraction imaging of an

object point in air through a medium with linear refractive index change is studied in detail，and

it is pointed out that the position of the imaging point in the medium with uniformly varying

refractive index is almost the same as that in the medium with uniform refractive index of

same thickness， except for the large angle of view from 80° to 90°. The reasoning methods and

conclusions in this paper may provide reference for the teaching and scientific research of related

contents.