Transverse deflection of a beam of rays in inhomogeneous locally isotropic media

An equation is derived for the transverse deflection of a beam of rays in the presence of a perpendicular component of the gradient of the Poynting vector amplitude. This equation can also describe one of the possible mechanisms of a transverse displacement of the focal waist when one-half of a focusing lens is illuminated by a plane circularly polarised wave. The transverse deflection is governed by the sign of the circular polarisation.