A lithographic apparatus is disclosed that includes a table, at least two target portions on the table or on an object on the table, and a surface material between the at least two target portions. The apparatus further includes an optical system configured to project a beam of radiation, along an optical path towards the table, with a cross-section to irradiate the at least two target portions at the same time. The apparatus further includes a shield moveable into the optical path to restrict the cross-section of the beam of radiation to restrict illumination between the at least two target portions, wherein the surface material between the at least two target portions would degrade when irradiated with radiation from the optical system.