Holographic flow cytometry based on Sagnac interferometer integrates single cell tomography and spatiotemporal analysis

Holographic flow cytometry has been widely used on both single cell and high throughput cells analysis. To perform real-time digital holographic recording, off-axis interferometer is one of the optimal solutions. Conventional offaxis interferometer setups, such as the Mach-Zehnder geometry, have difficulty producing stable holographic interference fringes under strong environmental disturbances. For this reason, Sagnac geometry could be a good candidate for future holographic microscopy, especially for biological experiments which will be performed during space travel. Here we will present a series of flow cytometry measurements based on Sagnac interferometer. We demonstrate that both single-cell tomography and spatiotemporal digital holography (STDH) can be implemented based on the holograms acquired by Sagnac system. By optimizing the reconstruction process and improving the hologram assembly method, the Sagnac structure can achieve the same imaging field of view (FoV) and resolution as conventional off-axis interferometry geometry. We believe that the digital holographic microscope based on the Sagnac optical geometry will be one of the possible strategies for implementing rapid cell detection in space missions.