Focal shift and focal switch in dual-focus systems
Focal shift and focal switch in dual-focus systems
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DOI：
10.1364/josaa.14.001297
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发表时间：
1997-06
影响因子：
1.9
通讯作者：
Yajun Li
中科院分区：
文献类型：
--
作者：
Yajun Li
所考虑的系统由一片薄衍射元件（菲涅耳波带片）和入射到衍射元件上的均匀会聚球面波组成。入射球面波的曲率中心和波带片的主焦点是系统的两个焦点。当系统的菲涅耳数减小到足够低的水平时，绝对最大强度点从前者切换到后者。这一效果的数学公式和物理解释。
The system under consideration consists of a piece of thin diffractive element (the Fresnel zone plate) and a uniform, converging spherical wave that is incident on the diffractive element. The center of curvature of the incident spherical wave and the primary focus of the zone plate are the two foci of the system. The point of absolute maximum intensity switches from the former to the latter when the Fresnel number of the system decreases to a sufficiently low level. Both a mathematical formulation and a physical interpretation of this effect are presented.