Abstract: An apparatus for and method of determining the alignment of a substrate in which a multiple alignment marks are simultaneously illuminated with spatially coherent radiation and the light from the illuminated marks is collected in parallel to obtain information on the positions of the marks and distortions within the marks.

Abstract: A substrate table is provided with an optical system that includes a first window and a second window arranged to allow radiation to pass into an optical arm. At least two mirrors are provided within the optical arm and are arranged to reflect radiation that is passed through the windows. At least two lenses are positioned to receive radiation reflected from the mirrors, wherein the first window is provided with a first alignment mark and the at least two mirrors and at least two lenses are arranged to form an image of the first alignment mark at the second window. A second alignment mark is provided in the second window, or in the substrate table at a location adjacent to the second window.