Figure 1: Schematic illustration of the spin Hall effect of light (SHEL). When a linearly polarized light beam is incident obliquely on an interface between two media with different indices of refraction, its circularly polarized components with opposite helicities ($σ+$ and $σ-$) are separated spatially in the direction perpendicular to the plane of incidence, as shown. The separation is on the subwavelength scale, but can easily reach values of $200nm$ or more, and can be tuned by varying the angle of incidence.