周期性结构衍射物的相位恢复方法

A Phase Retrieval Method for Diffracting Object of Periodic Structure

提出一种将G-S算法应用于周期性结构衍射物相位恢复的简便方法.通过研究周期性结构衍射物的衍射特性,建立了单个周期的频谱强度与入射光(波)束和各衍射光(波)束强度的关系,从而实现了将G-S算法应用于单周期的迭代计算.这不仅压缩了采样点数和计算量,也为强度检测提供了方便.通过数值模拟计算证明了这种方法的正确性.

G-S algorithm has been considered a widely applicable phase retrieval algorithm. But it requires great amount of calculations and its experimental requirements are too stringent; thus up to now, to the authors' best knowledge, it cannot be actually used in phase retrieval. The authors, in this paper, propose a simple but effective method to make it possible for G-S algorithm to be actually used in phase retrieval of diffracting object of periodic structure. The authors analyze diffraction characteristics of diffracting object of periodic structure and then establish an equation (eq.7 in the full paper) that relates spectrum intensity of a single period to both intensities of diffracted light (wave) bundles and intensity of lighting light (wave) bundle. Thus transform problem of many periods is converted into that of a single period; as a result, the amount of computations is greatly reduced. Eq.7 simplies experimental procedure by making point-by-point measurement of intensity data unnecessary, because the determination of spectrum intensity of a single period now depends on only measuring one by one the intensities of diffracted light (wave) bundles and the intensity of lighting light (wave) bundle. Any ordinarily available lighting light (wave) field has no deteriorating effect on the correct retrieval of phase by the authors' method; thus flexibility of experiment is much increased by the authors' method. The correctness of this method is proved by digital analogue calculations. Its application to the phase retrieval problem of holographic grating is also satisfactory.