Under the excitation of an impulse, the radiation field has to be evaluated in terms of precise Fresnel-Kirchhoffformula; otherwise, some important transient features would be lost.
Firstly according to radiation theory the boundary function of planar diffraction body is given, based on this condition the Kirchhoff diffraction formula is deduced and obtained.
根据辐射理论重新设定了平面衍射物的边界函数，并以此条件推导了基尔霍夫衍射公式，并赋予新的含义。
3
The zoning rules for two dimensional ring of Frensel zone plate is studied by means of Kirchhoff diffraction formula.