Sun Jiasong, Zuo Chao, Chen Qian
Opt Express. 2015 Oct 19;23(21):28031-49. doi: 10.1364/OE.23.028031.
In this work, an optimum frequency combination (OFC) method is proposed to reconstruct high quality phase information of the complex light field, which is really valuable for many objects such as optical elements and cells. It is shown that the difference image between two symmetrical separated, larger defocused planes contains a lot of lower frequency components of the phase distribution and the higher frequency components can be easily observed in the difference image between two nearly focused planes. Based on the phase transfer function (PTF), our method combines different frequency components with high Signal-to-Noise Ratio (SNR) together to estimate a more accurate frequency spectrum of the object's phase distribution without any complicated linear or nonlinear regression. Then, we can directly reconstruct a high-quality phase map through inverse Fourier transform. What's more, in order to compensate the phase discrepancy resulted from strong absorption in the intensity, an iterative compensation algorithm is proposed. Both the simulation and experimental results demonstrate that our iterative OFC (IOFC) method can give a computationally efficient and noise-robust phase reconstruction for absorptive phase objects with higher accuracy and fewer defocus planes.
在这项工作中，提出了一种最优频率组合（OFC）方法来重建复杂光场的高质量相位信息，这对于光学元件和细胞等许多物体来说非常有价值。结果表明，两个对称分离的较大散焦平面之间的差分图像包含大量相位分布的低频分量，而高频分量则很容易在两个近聚焦平面之间的差分图像中观察到。基于相位传递函数（PTF），我们的方法将具有高信噪比（SNR）的不同频率分量组合在一起，无需任何复杂的线性或非线性回归即可估计出更准确的物体相位分布频谱。然后，我们可以通过傅里叶逆变换直接重建高质量的相位图。此外，为了补偿强度中强吸收导致的相位差异，提出了一种迭代补偿算法。仿真和实验结果均表明，我们的迭代OFC（IOFC）方法能够以更高的精度和更少的散焦平面，为吸收性相位物体提供计算效率高且抗噪声的相位重建。
