The coddington is essentially a sphere with a slotcut in it to allow an aperture smaller than the pupil of the eye.
科丁顿放大镜实质上是一个球，球面上开槽，使得孔径小于眼的瞳孔。
2
On applying the diffraction theory and with the aid of the reciprocity theorem, an approximate formula for the radiation field of a slotcut in a metal sheet of finite size is derived.
本文应用绕射理论并借助于互易定理，导出了一个在有限尺寸金属平板上割出的一条裂缝的近似辐射埸公式。
3
Simply cut a slot in the lid to put change in, and let your child decorate the outside as he or she chooses.