Abstract: The invention relates to a polarizing beam splitter device, an interferometer module system, a lithographic apparatus, and a device manufacturing method. The polarizing beam splitter device includes an optical element and a polarizing beam splitter layer. The optical element includes a retroreflector surface having three mutually perpendicular faces of high optical quality, a radiation beam passage surface and a handling surface. By designing the optical element, in particular the handling portion, to the shape of a beam splitter element, such as a prism, the handling portion, and thus the polarizing optical beam splitter device etc. itself, may be made more compact and with fewer surfaces to be polished and/or antireflection-coated. The positioning of the parts in a beam splitter is more reliable.

Abstract: An improved lithographic interferometer system, is presented herein. The lithographic interferometer system comprises a beam generating mechanism, mirrors which reflect those beams, and detection devices for detecting an interference pattern of overlapping reflected beams. The beam generating mechanism comprises a beam-splitter, which splits the beams into reference beams and measuring beams, a reference mirror that provides a plane mirror interferometer, and a reflective surface that emits at least one reference beam used in a differential plane mirror interferometer.

Abstract: An improved lithographic interferometer system, is presented herein. The lithographic interferometer system comprises a beam generating mechanism, mirrors which reflect those beams, and detection devices for detecting an interference pattern of overlapping reflected beams. The beam generating mechanism comprises a beam-splitter, which splits the beams into reference beams and measuring beams, a reference mirror that provides a plane mirror interferometer, and a reflective surface that emits at least one reference beam used in a differential plane mirror interferometer.

Abstract: Embodiments of the invention include an interferometer measurement system in which at least one reflective surface is arranged such that, in use, the beam path of interferometer radiation of the interferometer measurement system incident on the at least one reflective surface has an offset angle in the range of from 0.1 to 10 milliradians with respect to the normal to the at least one reflective surface. In that way, the effect of spurious radiation on the interferometer measurement system produced within the interferometer measurement system may be suppressed. In another embodiment, a parallel-sided plate is used in an interferometer measurement system to obtain a signal dependent on the angle of a beam of radiation reflected from a mirror. In that way, the flatness of the mirror can be mapped. One surface of the plate is a beam-splitter and the opposite surface of the plate is a reflector.

Abstract: A lithographic apparatus is disclosed. The apparatus includes a radiation system for supplying a beam of radiation, and a support structure for supporting a patterning device. The patterning device serves to pattern the beam of radiation according to a desired pattern. The apparatus also includes a projection system for projecting the patterned beam of radiation onto a target portion of a substrate, and an assembly for determining a spatial position of the patterning device relative to the projection system. The assembly includes a measuring unit that has a plurality of sensors that are mounted on the projection system.

Abstract: In a lithographic projection apparatus, a measuring system configured to measure the position of the projection system relative to a reference frame includes sensors rigidly mounted in relation to counterpart sensors of a measuring system measuring the substrate table position. An angular encoder which sends light from a target down two optical paths having opposite sensitivities to tilt is used to measure rotation of the projection system about its optical axis.

Abstract: In an interferometric displacement measuring system, a correction for beamshear is made. The correction may be a polynomial of a variable proportional to the length of the optical path traversed by the measurement beam and the angle of the measurement mirror. The correction compensates for errors caused by non-planarity of the wavefront of the measurement beam.