Fabry-Pérot Microscopy for Improved Contrast Enhancement and 3D Cellular Imaging

Fabry-Pérot Microscopy (FPM) integrates a lab-on-a-chip optical cavity and tunable light source in a label-free imaging technique that enhances contrast and enables pseudo-three-dimensional imaging in transparent biological samples. By integrating a fixed-length Fabry-Pérot cavity into a coated microfluidic cell, FPM selectively highlights structures of defined optical thickness through resonance-based interference. We demonstrate that this architecture preserves lateral resolution while providing up to 20-fold contrast enhancement compared to conventional wide-field microscopy. Using human epithelial cells, blood components, and E. coli bacteria, we show that FPM enables clear visualization of subcellular features and discrimination of cell types. Spectrally resolved image stacks are used to extract pixel-wise optical thickness maps, from which physical thickness and refractive index can be derived. These parameters reveal nanoscale structural differences and offer routes to biophysical characterization. Notably, the system operates without mechanical scanning the cavity, using spectral tuning alone to generate images. FPM is compatible with standard microscope optics, and functions under static or flow-compatible conditions, making it suitable for high-throughput cytometry and in vitro diagnostics. These results establish FPM as a versatile extension to wide-field microscopy, enabling contrast-tunable, quantitative imaging of biomedical specimen.