An imaging optical system has a plurality of mirrors which image an object field in an object plane in an image field in an image plane. The imaging optical system has a pupil obscuration. The last mirror in the beam path of the imaging light between the object field and the image field has a through-opening for the passage of the imaging light. A penultimate mirror of the imaging optical system in the beam path of the imaging light between the object field and the image field has no through-opening for the passage of the imaging light. The result is an imaging optical system that provides a combination of small imaging errors, manageable production and a good throughput for the imaging light.

An imaging apparatus includes a first reflection optical system and a second reflection optical system having mutually different optical axes, each of the first and second reflection optical systems includes a plurality of reflecting surfaces, a first imaging portion configured to receive an imaging light reflected by the first reflection optical system, a second imaging portion configured to receive an imaging light reflected by the second reflection optical system, a first member, a second member, and a frame. A part of the plurality of reflecting surfaces of the first reflection optical system are reflecting surfaces provided on the frame. Among the plurality of reflecting surfaces of the first reflection optical system, a final-stage reflecting surface configured to reflect the imaging light toward the first imaging portion is a first reflecting surface formed on a surface of the first member.

A magnifying imaging optical unit serves for inspecting lithography masks which are used in EUV projection exposure. The imaging optical unit comprises at least two mirrors (M1 to M4) which can be displaced relative to one another for changing a magnification value. According to a further aspect, a magnifying imaging optical unit comprises at least one mirror (M1 to M4) and a magnification value, which can be changed by displacement of at least two mirrors (M1 to M4) relative to one another. Here, the magnification value can be changed between a minimum magnification value, which is greater than 100, and a maximum magnification value, which is greater than 200. An imaging optical unit emerges, which can be adapted to, in particular, mask structures with different sizes.

Optimal angular field mappings that provide the highest contrast images for back-scanned imaging are given. The mapping can be implemented for back-scanned imaging with afocal optics including an anamorphic field correcting assembly configured to implement a non-rotationally symmetric field mapping between object space and image space to adjust distortion characteristics of the afocal optics to control image wander on a focal plane array. The anamorphic field correcting assembly can include one or more mirrors having non-rotationally symmetric aspherical departures.

An on-gimbal telescope pointing assembly can comprise a head mirror operable to rotate to adjust an elevation angle of the pointing assembly and an all-reflective telescope operable to rotate to adjust an azimuth angle of the pointing assembly. The all-reflective telescope can comprise a fold mirror defining an output coude path of the all-reflective telescope. The pointing assembly can be operable to rotate about the coude path such that receiving optics can remain fixed while the pointing assembly rotates.

An imaging optical unit for projection lithography has a plurality of mirrors for guiding imaging light from an object field into an image field. The object field is spanned by a first, larger object field dimension and along a second, smaller object field dimension. The imaging optical unit has at least two GI mirrors and at least one NI mirror. The NI mirror is arranged between two GI mirrors in the imaging light beam path. A used reflection surface of the NI mirror has an aspect ratio between a surface dimension along a first reflection surface coordinate and a surface dimension along a second reflection coordinate parallel to the second object field dimension. The aspect ratio being less than 4.5. An imaging optical unit with reduced production costs emerges.

Beam guiding devices for guiding a laser beam, in particular in a direction towards a target region for producing extreme ultraviolet (EUV) radiation, include an adjustment device for adjusting a beam diameter and an aperture angle of the laser beam. The adjustment device includes a first mirror having a first curved reflecting surface, a second mirror having a second curved reflecting surface, a third mirror having a third curved reflecting surface, a fourth mirror having a fourth curved reflecting surface, and a movement device configured to adjust the beam diameter and the aperture angle of the laser beam by moving the first reflecting surface and the fourth reflecting surface relative to one another and, independently thereof, moving the second reflecting surface and the third reflecting surface together relative to the first reflecting surface and the fourth reflecting surface.

A head-up display projects an image on a windshield to allow a viewer to visually observe a virtual image. The head-up display includes a display device, a relay optical system, and a projection optical system. The display device displays an image. The relay optical system provides the image displayed by the display device as an intermediate image. The projection optical system reflects the intermediate image provided by the relay optical system to project the intermediate image on the windshield.

A projection optical unit for EUV projection lithography has a plurality of mirrors for imaging an object field into an image field with illumination light. At least one of the mirrors is an NI mirror and at least one of the mirrors is a GI mirror. A mirror dimension Dx of the at least one NI mirror in a plane of extent (xz) perpendicular to a plane of incidence (yz) satisfies the following relationship:

4 LLWx/IWPV.sub.max<Dx.

A mirror dimension Dy of the at least one GI mirror in the plane of incidence (yz) satisfies the following relationship:

4 LLWy/(IWPV.sub.max cos(a))<Dy.

Optimal angular field mappings that provide the highest contrast images for back-scanned imaging are given. The mapping can be implemented for back-scanned imaging with afocal optics including an anamorphic field correcting assembly configured to implement a non-rotationally symmetric field mapping between object space and image space to adjust distortion characteristics of the afocal optics to control image wander on a focal plane array. The anamorphic field correcting assembly can include one or more mirrors having non-rotationally symmetric aspherical departures.