3D resolution measure for multifocal plane microscopy

The distance separating two biomolecules in close proximity is an important determinant of the nature of their interaction. While much focus has been given to resolving distances in 2D, the 3D cell in which biological interactions occur necessitates the evaluation of resolution in 3D. Recently, we introduced an information-theoretic 3D resolution measure which predicts that the resolution of an optical microscope is unlimited, and that it improves as more photons are detected from the imaged molecules. Here, we investigate the 3D resolution measure for a multifocal plane microscope. Used for the simultaneous imaging of distinct focal planes within a specimen, multifocal plane microscopy has important applications in the tracking of microscopic objects in 3D. By comparing their 3D resolution measures, we determine the circumstances under which a two-plane microscope setup offers better re- solvability than a comparable conventional microscope.