正交有限角投影局部基函数展开法重建三维折射率场

Reconstruction of 3D Reflective Index Field from Limited Orthogonal Projections Using Expansion of Local Basic Function

在对移相干涉测量三维折射率场研究的基础上,研究了正交小角度光路的设置.对于有限角度的少数投影层析重建,采用了连续可导的局部基函数展开折射率场函数.为了提高重建精度,提出了基于遗传算法的多松弛因子迭代重建算法.实验和数值仿真表明,正交有限角少数投影的测量方法可以有效减少测量数据量;采用连续可导的局部基函数展开,并在迭代过程中引入多个可变松弛因子,最大误差不大于5%,平均误差不大于1%的重建精度,较传统网格法提高了约40%.

Image reconstruction by sparse data is an important and intractable problem in the field of OCT （optical computerized tomography）. On the basis of previous work on the measurement of refractive index distribution by phase-shifting interferometry, the feasibility of reconstruction from orthogonal projections within limited narrow views is discussed. Local differentiable basic function was used to expand the refractive index filed, and consequently for precision in reconstruction, an iterative reconstruction algorithm with multiple-changeable relaxation factors is presented, based on genetic algorithm. Experiments and numerical simulation showed that the method of reconstruction from a few orthogonal projections within limited views caused a marked reduction in the quantity of measurement data. It is proved that the application of multi-changeable relaxation factors to the process of iteration makes the reconstruction precision considerably improved reaching a max error of no more than 5 % and an average error less than 1%, when compared with the conventional grid method, associated with the expansion of local differentiable basic function.