相因子判断法分析菲涅耳波带片的衍射场

Study of diffraction fields of Fresnel zone plate based on wavefront phase factor

基于波前相因子判断法,并考虑到波带片孔径的影响,揭示了波带片的衍射场所含基元成分及各成分在衍射场的积分表达式,并导出了沿轴的衍射场振幅分布公式及沿轴的振幅分布曲线,得到多个实焦斑的横向半值线宽和轴向半值线宽公式.本研究为波带片作为一种光学元件提供了一理论基础.

Based on the method of wavefront phase-factor and considering of the influence of limited aperture of zone plate,we analyse the diffraction fields by Fresnel zone plate which contains three components.The corresponding integral expressions of the diffraction fields are given,the formulae of the amplitude distribution of diffraction fields alone axis are presented and a series of curves are shown.Finally,the transverse line-width and the axial line-width of that real focal-spot are obtiained.This study may further provide a theoretical foundation to optical element by Fresnel zone plate.