Abstract: An optical apparatus for a lithography system has at least one optical element comprising an optical surface. The optical apparatus also has one or more actuators for deforming the optical surface. The optical element comprises a strain gauge device for determining the deformation of the optical surface. The gauge device comprises: a) at least one path length device for generating a measurement spectrum of a measurement radiation, wherein the path length device comprises a grating device for the measurement radiation and/or a resonator device for the measurement radiation; and/or b) at least one waveguide, wherein the at least one waveguide and/or the at least one grating device and/or the at least one resonator device are formed by the substrate element.

Abstract: An optical apparatus for a lithography system comprises at least one optical element comprising an optical surface. The optical apparatus also comprises one or more actuators for deforming the optical surface. A strain gauge device is provided for determining the deformation of the optical surface. The strain gauge device comprises at least one optical fiber that maintains polarization.

Abstract: A method of assembling a facet mirror of an optical system, in which facets of the facet mirror are imaged onto a field plane of the optical system, includes: a) determining positions of the facets of the facet mirror relative to interfaces of the facet mirror, with the aid of which the facet mirror is able to be connected to a support structure; b) calculating an actual position of an object field of the optical system arising for the facet mirror in the field plane; and c) arranging spacers between the interfaces and the support structure so that the object field in the field plane is brought from the calculated actual position to a target position.

Abstract: A method of assembling a facet mirror of an optical system, in which facets of the facet mirror are imaged onto a field plane of the optical system, includes: a) determining positions of the facets of the facet mirror relative to interfaces of the facet mirror, with the aid of which the facet mirror is able to be connected to a support structure; b) calculating an actual position of an object field of the optical system arising for the facet mirror in the field plane; and c) arranging spacers between the interfaces and the support structure so that the object field in the field plane is brought from the calculated actual position to a target position.

Abstract: A measuring assembly for the frequency-based determination of the position of a component, in particular in an optical system for microlithography, includes at least one optical resonator, which has a stationary first resonator mirror, a movable measurement target assigned to the component, and a stationary second resonator mirror. The second resonator mirror is formed by an inverting mirror (130, 330, 430, 530), which reflects back on itself a measurement beam coming from the measurement target.

Abstract: A measuring assembly for the frequency-based determination of the position of a component, in particular in an optical system for microlithography, includes at least one optical resonator, which has a stationary first resonator mirror, a movable measurement target assigned to the component, and a stationary second resonator mirror. The second resonator mirror is formed by an inverting mirror (130, 330, 430, 530), which reflects back on itself a measurement beam coming from the measurement target.