Nonlinear delayed fluorescence in confocal scanning microscopy. Point-spread-function analysis

Generation of the signal beam in the confocal scanning fluorescence microsc opy by means of nonlinear delayed fluorescence phenomenon based on triplet- triplet annihilation is proposed. From the point of view of the spatial res olution of three-dimensional confocal imaging the superiority of the phenom enon proposed here over the classical two-photon fluorescence is demonstrat ed. This is done in terms of axial and lateral point spread functions compu ted for the assumed model of nonlinearity.