Impact of axial chromatic aberration on color-multiplexed differential phase contrast microscopy: A quantitative study

Color-multiplexed differential phase contrast (cDPC) imaging relies on deconvolving phase gradient images with phase transfer function (PTF) to extract quantitative phase information. Typically, the PTF used in the deconvolution process is assumed to be ideal. However, in practice, the presence of axial chromatic aberration causes actual PTF deviates from the ideal state, further reducing the phase reconstruction accuracy in cDPC. Therefore, the axial chromatic aberration is closely associated with the phase reconstruction accuracy in cDPC. Nevertheless, there is still a lack of quantitative methods to analyze the impact of axial chromatic aberration on the phase reconstruction accuracy of cDPC system. In this study, we propose a method to quantify the effect of axial chromatic aberration on phase reconstruction quality. This approach involves analyzing the error in the PTF affected by axial chromatic aberration, compared to the ideal PTF. Simulation and experimental results have validated the effectiveness of the proposed method. Furthermore, by computing PTF errors across different imaging plane positions, we determine the imaging plane position that has minimal phase reconstruction error in cDPC. Compared to the traditional approach of determining the optimal imaging plane position through image contrast in experiment, the imaging plane position determined by our method has smaller phase reconstruction error and fewer reconstruction artifacts.