  Fluorescence lifetime imaging microscopy (FLIM) is an important technique to
understand the chemical micro-environment in cells and tissues since it
provides additional contrast compared to conventional fluorescence imaging.
When two fluorophores within a diffraction limit are excited, the resulting
emission leads to non-linear spatial distortion and localization effects in
intensity (magnitude) and lifetime (phase) components. To address this issue,
in this work, we provide a theoretical model for convolution in FLIM to
describe how the resulting behavior differs from conventional fluorescence
microscopy. We then present a Richardson-Lucy (RL) based deconvolution
including total variation (TV) regularization method to correct for the
distortions in FLIM measurements due to optical convolution, and experimentally
demonstrate this FLIM deconvolution method on a multi-photon microscopy
(MPM)-FLIM images of fluorescent-labeled fixed bovine pulmonary arterial
endothelial (BPAE) cells.
