Three-dimensional tracking of dynamic nanoparticles based on direct correlation method in fluorescence self-interference microscopy

Single-molecule localization microscopy (SMLM) has been applied as a powerful tool in the visualization of biological samples. The obtained details about the fine structures inside the cells or tissues, on the spatial scale of much smaller than the size that defined by the diffraction limit of the optical system, are important for the understanding of the dynamics and organization of the living process. In this paper, by exploring the direct correlation of real-valued holograms in fluorescence self-interference digital holography (SIDH), an imaging method is proposed for 3D localization and dynamic 3D tracking of nanoparticles. The trend of 3D localization accuracy under different axial positions is studied in detail. An appropriate mathematical model is used to fit the cross-correlation curve of the hologram to determine the axis coordinate of the point source. The validity of the proposed method is demonstrated in simulation and experiments. This method does not require phase shift technology. The 3D coordinates of particles can be obtained through a single real-valued hologram using the proposed algorithm. Therefore, we believe the developed method has unique advantages in the 3D visualization of dynamic events that happened on the biomolecules inside the cellular structures.