Kumar Abhishek, Drexler Wolfgang, Leitgeb Rainer A
Opt Express. 2014 Jun 30;22(13):16061-78. doi: 10.1364/OE.22.016061.
In this paper a theoretical model of the full field swept source (FF SS) OCT signal is presented based on the angular spectrum wave propagation approach which accounts for the defocus error with imaging depth. It is shown that using the same theoretical model of the signal, numerical defocus correction methods based on a simple forward model (FM) and inverse scattering (IS), the latter being similar to interferometric synthetic aperture microscopy (ISAM), can be derived. Both FM and IS are compared quantitatively with sub-aperture based digital adaptive optics (DAO). FM has the least numerical complexity, and is the fastest in terms of computational speed among the three. SNR improvement of more than 10 dB is shown for all the three methods over a sample depth of 1.5 mm. For a sample with non-uniform refractive index with depth, FM and IS both improved the depth of focus (DOF) by a factor of 7x for an imaging NA of 0.1. DAO performs the best in case of non-uniform refractive index with respect to DOF improvement by 11x.
本文基于角谱波传播方法提出了全视野扫频光源（FF SS）OCT信号的理论模型，该方法考虑了成像深度的离焦误差。结果表明，使用相同的信号理论模型，可以推导出基于简单前向模型（FM）和逆散射（IS）的数值离焦校正方法，后者类似于干涉合成孔径显微镜（ISAM）。将FM和IS与基于子孔径的数字自适应光学（DAO）进行了定量比较。FM的数值复杂度最低，在三种方法中计算速度最快。在1.5mm的样本深度范围内，所有三种方法的信噪比提高均超过10dB。对于折射率随深度不均匀的样本，对于成像数值孔径为0.1的情况，FM和IS均将焦深（DOF）提高了7倍。在折射率不均匀的情况下，就DOF改善而言，DAO表现最佳，提高了11倍。
