Interface unit, lithographic projection apparatus comprising such an interface unit and a device manufacturing method

An interface unit for transferring objects, such as substrates, is presented. The interface unit includes a first object transfer path to transfer objects between a track configured to process objects and a lithographic exposure unit configured to expose objects, wherein the interface unit is also provided with a second object transfer path extending through a closable transfer opening to an external space to transfer objects between the external space and the lithographic exposure unit. Furthermore, the invention relates to a lithographic apparatus provided with a lithographic exposure unit and an interface unit according to the invention.