Fabry‐Pérot Microscopy for Improved Contrast Enhancement and Quantitative Phase Imaging

Fabry-Pérot microscopy (FPM) is a label-free imaging technique that combines a microfluidic optical cavity with a tunable light source to enhance contrast and enable quantitative phase imaging. It integrates a fixed-length Fabry-Pérot cavity into a coated microfluidic channel and utilizes resonance-based interference to selectively highlight structures with specific optical thickness. This design preserves lateral resolution while providing > 20-fold contrast enhancement compared to conventional wide-field microscopy. Demonstrations with human oral epithelial cells, blood components, and E. coli show clear visualization of subcellular features and differentiation of cell types. Notably, FPM achieves imaging through spectral tuning rather than mechanical scanning, ensuring faster and more stable operation. The system is compatible with standard microscope optics and works under both static and flow conditions, offering significant potential for high-throughput cytometry, biological research, and in vitro diagnostics. These results establish FPM as a versatile extension of wide-field microscopy, enabling contrast-tunable, quantitative imaging of biomedical samples.