Investigation of longitudinal spatial coherence induced by a partially spatially coherent source

Abstract

In this study, we report longitudinal spatial coherence (LSC) generated from an extended partially spatially coherent source. This treatment differs from traditional LSC studies, which consider the source to be strictly spatially incoherent. We found that the higher transverse spatial coherence (TSC) of the source resulted in a smaller longitudinal coherence length with strong modulations. In addition, the influence of propagation distance is studied through the position of the reference plane, which was not apparent in conventional LSC formulations. The result of the assumption of TSC and propagation distance is reduced LSC contrast, which may affect the quality of the resulting images. The spatial correlation between two transverse points on different planes is demonstrated to compensate for the degradation in longitudinal coherence caused due to some misalignment. Understanding the effects of parameters such as propagation distance and partial coherence of the source can help in designing optical systems to achieve optimal LSC contrast in optical imaging modalities.