Beyond the weak-scattering limit: accurate Kramers-Kronig phase imaging of high-contrast reflective surfaces via pupil modulation

초록

Here, we present a pupil-modulation method that selectively attenuates the scattered field from an object, enabling quantitatively accurate phase retrieval based on spatial-domain Kramers-Kronig (KK) relations. Numerical simulations show that conventional KK reconstruction suffers from increasing phase errors when the weak-scattering assumption-which requires the detected field to be dominated by ballistic light-is violated due to increased phase contrast, amplitude variation, or spatial phase complexity. The proposed method is experimentally validated on two representative reflective samples: one with uniform reflectivity and another exhibiting amplitude variations. The retrieved phase maps demonstrate close agreement with both theoretical predictions and off-axis interferometric measurements. This work establishes a practical pathway for extending KK-based quantitative phase imaging to strongly scattering and reflective surfaces, offering a non-interferometric, deterministic, and non-iterative tool for metrology applications with minimal computational overhead.

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