Single-shot color-multiplexed quantitative phase imaging with Kramers-Kronig relations.

Single-shot quantitative phase imaging (QPI) promises high-speed, label-free observation of dynamic biological processes, but remains challenged by limited reconstruction fidelity, weak-object assumptions, and the inability to recover both amplitude and large phase delays. In this Letter, we introduce CMKK-QPI, a single-shot QPI framework that synergizes color-multiplexed oblique illumination with iterative processing based on the Kramers-Kronig (KK) relations. By spectrally encoding angular diversity into a single color exposure, CMKK-QPI enables simultaneous acquisition of multiple intensity measurements without sacrificing temporal resolution. An initial complex-field estimate is retrieved via the KK relations and iteratively refined to jointly reconstruct amplitude and phase. Experiments on resolution targets, biological tissues, and live cells demonstrate that CMKK-QPI achieves a resolution corresponding to twice the coherent diffraction limit and phase accuracy comparable to multi-frame Fourier ptychographic microscopy, with only a single exposure and convergence within 5 iterations. Importantly, CMKK-QPI robustly handles large phase variations and enables long-term, high-speed imaging of dynamic cellular morphology at 30 Hz. With minimal data redundancy and high computational efficiency, CMKK-QPI provides a practical solution for high-speed, label-free imaging of dynamic biological samples.