Single-shot Non-Invasive Quantitative Phase Microscopy for Dynamic 3D Imaging

The transparent nature of biological samples complicates the study of dynamic cellular processes using traditional microscopy, often requiring external agents that cause photodamage and cell death. Quantitative Phase Microscopy (QPM) provides a non-invasive, label-free alternative by estimating the refractive index of these phase objects. However, existing systems face challenges with accuracy, cost, and real-time monitoring, as they typically rely on multiple captures and expensive components. To address these limitations, we introduce an innovative QPM system utilizing a common-path interferometer with a birefringent liquid crystal as the phase modulator. A polarization-sensitive camera enables single-shot acquisition of phase-shifted images, and a four-step phase-shifting algorithm optimized for the Pancharatnam-Berry geometric phase delivers highly accurate phase measurements. With gentle illumination to reduce phototoxicity and a 1 Hz frame rate for long-term monitoring, the system achieves a maximum standard deviation of ±42 nm and noise fluctuations of ±2.5 nm. Simple and robust, our QPM system offers an affordable, reliable solution for noninvasive, long-term research applications.