Nanoholes and nanoslits are efficient sources of plasmons on metal surfaces. We use arc-shaped nanoslits in thin silver
films for generating sub-wavelength plasmon spots with enhanced optical near-fields. Introduction of a continuous phase
delay along the nanoslits shifts the position of the plasmon focus spot. We show experimentally that such a phase control
allows to scan the plasmon focus by micrometers with a nanometer precision and to launch it on separate silver
nanowires placed in the focal plane. These experiments, demonstrating scanning and multiplexing functionality, show
the feasibility of the nanoscale manipulation with optical fields.