用波阵面图分析光阑衍射及其实用性举例

Diffraction of Aperture Analyzed by Wavefront Diagram and Its Applications

根据边界衍射波具有π位相跃变的性质,利用波阵面图分析了平面波或球面波经光阑的衍射。该方法不仅适用于光阑半径远大于波长时的情况,也适用于光阑半径接近于波长时的情况。从中可得到菲涅耳衍射区的许多特性。作为一个例子,提出和验证了在发散球面波入射情况下可将菲涅耳数等于1的点拉至无穷远的结论。结果证实了边界衍射波中π位相跃变的存在,并表明了其实用性。

Based on the concept that there is a π phase jump property in the boundary wave, the diffraction of the plane wave and the spherical wave through an aperture is analyzed by means of wavefront diagram. This method can be used not only in the case where the aperture radius a is much larger than wavelength λ, but also in the case when a is comparable to λ. It is shown that many properties of diffraction in the Fresnel region can be obtained. As an example, a method to put the point of unit Fresnel number to infinity is suggested and demonstrated. The results of this report confirmed the existence of the π phase jump concept and its value in practical applicalions.