Image estimation accounting for point-spread function depth variation in three-dimensional fluorescence microscopy

An approximate model for optical-sectioning microscopy describing depth-varying imaging is developed. The model incorporates changes in the point-spread function due to refractive index mismatch between the immersion medium and the specimen. which causes spherical aberration that worsens with increasing depth tinder the coverslip. Comparison of model predictions to measured images from a bead phantom shows that the approximate model captures the main features in the data. The model presented in this paper is the first step towards depth-variant image estimation for optical-sectioning microscopy. An expectation maximization algorithm for maximum-likelihood restoration based on this model is also presented.