Approach to multiparticle parallel tracking in thick samples with three-dimensional nanoresolution.

This Letter proposes a method referred to as distorted grating (DG) and double-helix point spread function (DH-PSF) combination microscopy (DDCM), which is capable of multiparticle parallel localization and tracking in a transparent sample thicker than 10 μm, the thickness of cells. A special phase mask, combining the field depth extension capabilities of DG with the three-dimensional (3D) nanolocalization capabilities of the DH-PSF, is designed for multiparticle parallel localization. Time-lapse tracking of one particle moving along the z axis and parallel tracking of two particles are simulated. Results demonstrate that, with only a single snapshot, particles can be localized, tracking with 3D nanoresolution wherever they are. The theoretical localization precisions of DDCM, DH-PSF, and multifocus microscopy are compared. DDCM results in almost constant localization precisions in all three dimensions for a depth of field larger than 10 μm. DDCM is expected to become a tool in investigations of important dynamic events in living cells.