Ledwig Patrick, Robles Francisco E
Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332, USA.
APL Photonics. 2023 Apr 1;8(4):041301. doi: 10.1063/5.0123206. Epub 2023 Apr 3.
Optical diffraction tomography is a powerful technique to produce 3D volumetric images of biological samples using contrast produced by variations in the index of refraction in an unlabeled specimen. While this is typically performed with coherent illumination from a variety of angles, interest has grown in partially coherent methods due to the simplicity of the illumination and the computation-free axial sectioning provided by the coherence window of the source. However, such methods rely on the symmetry or discretization of a source to facilitate quantitative analysis and are unable to efficiently handle arbitrary illumination that may vary asymmetrically in angle and continuously in the spectrum, such as diffusely scattered or thermal sources. A general broadband theory may expand the scope of illumination methods available for quantitative analysis, as partially coherent sources are commonly available and may benefit from the effects of spatial and temporal incoherence. In this work, we investigate partially coherent tomographic phase microscopy from arbitrary sources regardless of angular distribution and spectrum by unifying the effects of spatial and temporal coherence into a single formulation. This approach further yields a method for efficient computation of the overall systems' optical transfer function, which scales with ( ), down from ( ) for existing convolutional methods, where is the number of spatial voxels in 3D space and is the number of discrete wavelengths in the illumination spectrum. This work has important implications for enabling partially coherent 3D quantitative phase microscopy and refractive index tomography in virtually any transmission or epi-illumination microscope.
光学衍射层析成像是一种强大的技术，可利用未标记样本中折射率变化产生的对比度来生成生物样本的三维体积图像。虽然这通常是通过从各种角度进行相干照明来实现的，但由于照明的简单性以及光源相干窗口提供的无需计算的轴向切片，部分相干方法的关注度日益提高。然而，此类方法依赖于光源的对称性或离散化来促进定量分析，并且无法有效处理在角度上不对称且在光谱上连续变化的任意照明，例如漫散射光源或热光源。一种通用的宽带理论可能会扩大可用于定量分析的照明方法的范围，因为部分相干光源通常是可用的，并且可能会受益于空间和时间非相干性的影响。在这项工作中，我们通过将空间和时间相干性的影响统一到一个单一公式中，研究了来自任意光源的部分相干层析相显微镜，而不考虑角度分布和光谱。这种方法还产生了一种有效计算整个系统光学传递函数的方法，其计算量与（ ）成比例，相比现有卷积方法的（ ）有所降低，其中 是三维空间中的空间体素数量， 是照明光谱中的离散波长数量。这项工作对于在几乎任何透射或落射照明显微镜中实现部分相干三维定量相显微镜和折射率层析成像具有重要意义。
