Enhanced performance for single-shot quantitative phase imaging based on spatial frequency modulation using the phase transfer function

Quantitative phase imaging (QPI) is a valuable technique for non-invasive, label-free characterization of transparent specimens, offering access to parameters such as refractive index and thickness. Among various QPI methods, transport-of-intensity equation-based approaches are attractive due to their non-interferometric implementation and compatibility with partially coherent illumination. However, conventional finite difference and polynomial fitting techniques often involve trade-offs between spatial resolution and noise robustness, and require sequential acquisition of defocused intensity distributions. In this study, we propose a single-shot QPI method based on spatial frequency modulation and phase transfer function (PTF) analysis. Multiple defocused intensity distributions are captured simultaneously, and the defocus distances are selected using the PTF, enabling accurate phase reconstruction without prior knowledge of the object or the system. Experimental results confirm that the proposed method outperforms conventional single-shot QPI techniques in terms of phase reconstruction quality.