Duality between spatial and angular shift in optical reflection

We report a unified representation of the spatial and angular Goos-Hanchen and Imbert-Fedorov shifts that occur when a light beam reflects from a plane interface. We thus reveal the dual nature of spatial and angular shifts in optical beam reflection. In the Goos-Hanchen case we show theoretically and experimentally that this unification naturally arises in the context of reflection from a lossy surface (e. g., a metal)