采用样品转动结构的光学衍射层析技术存在“苹果核频谱缺失”的问题,为此,本文提出傅里叶衍射映射正约束迭代算法以恢复缺失频谱,实现高精度折射率层析成像.首先基于光学衍射层析成像原理,采用带有样品转动装置的数字全息显微成像系统记录下360°视角内各个角度的显微全息图,计算得到每个角度的复振幅像分布;然后运用傅里叶衍射映射和正约束迭代相结合的衍射层析成像算法,计算得到样品内部折射率的三维分布.实验结果表明,该方法能有效地恢复缺失频谱,高精度地测量微小样品内部的折射率三维分布.

In optical diffraction tomography with specimen rotation,the set of captured frequencies exhibits a missing space called missing apple core,an algorithm,in which Fourier mapping algorithm was combined with iterative constraint algorithm,was proposed to acquire the missing frequencies and reconstruct a high-resolution refractive index map.First,based on the theory of digital holographic microtomography with sample rotation,the experiment system was set up and the digital holograms were acquired at regularly-spaced angular positions within 360° viewing angle.Then,the complex field images were calculated from the holograms.Last,the high-resolution three-dimensional refractive index map was reconstructed by the proposed algorithm.The experimental results demonstrate that the algorithm is feasible and effective for acquiring the missing apple core frequencies and achieving the high-resolution three-dimensional refractive index distribution.