Nonparaxial optical transfer function for arbitrary illumination in partially coherent imaging systems and the oblique source application

Abstract

Recent research in quantitative phase and refractive index microscopy showed promising results with methods using a partially coherent imaging setup, such as partially coherent optical diffraction tomography. For these methods, the phase optical transfer function (POTF), which describes the transmission of spatial frequencies by the imaging system, is crucial. Here, a one-dimensional integral representation of the POTF for imaging systems with arbitrary illumination is derived. It generalizes the existing expression, which is limited to axially symmetric setups. From the general integral form, an analytical solution is derived for the case of oblique homogeneous disk-shaped illumination. This demonstrates the potential of the general representation by offering an additional approach for illumination design in quantitative phase and refractive index microscopy.