An imaging optical unit for projection lithography has a plurality of mirrors for imaging an object field into an image field with imaging light guided along a path from the object field to the image field. The penultimate mirror in the path has no passage opening to pass the imaging light. The imaging optical unit has a stop to predefine an outer marginal contour of a pupil of the imaging optical unit. The stop is between the penultimate and last mirrors in the path. The imaging optical unit can have exactly one stop for predefining at least one section of the outer pupil marginal contour. An entrance pupil of the imaging optical unit can be upstream of the object field. The imaging optical unit can be well defined regarding its pupil and exhibit desirable properties for projection lithography.

A lithographic apparatus includes a projection system which includes a plurality of optical elements configured to project a beam of radiation onto a radiation sensitive substrate. The lithographic apparatus also includes a metrology frame structure which includes a part of one or more optical element measurement systems to measure the position and/or orientation of at least one of the optical elements. The plurality of optical elements, a patterning device stage, and a substrate stage are arranged such that, in a two dimensional view on the projection system, a rectangle is defined such that it envelops the plurality of optical elements, the patterning device stage, and the substrate stage. The rectangle is as small as possible. The metrology frame structure is positioned within the rectangle.

An imaging optical unit comprises a plurality of minors for imaging an object field into an image field. The imaging optical unit has an image-side numerical aperture greater than 0.55. Each mirror is configured so that it can be measured by a testing optical unit having at least one DOE with a predetermined maximum diameter for test wavefront generation. For the complete measurement of all reflection surfaces of the minors, a maximum number of DOEs of the testing optical unit and/or a maximum number of DOE test positions of the at least one DOE of the testing optical unit comes into play, which is no more than five times the number of minors in the imaging optical unit. The result is an imaging optical unit in which a testing-optical measurement remains manageable even in the case of a design with an image-side numerical aperture which is relatively large.

An imaging optical unit comprises a plurality of mirrors for imaging an object field in an object plane into an image field in an image plane. An image-side numerical aperture is greater than 0.55. A ratio between an object/image offset and a meridional transverse direction is at least 0.5. A ratio between a working distance between the object plane and a reflection portion, closest to the object plane, of one of the mirrors and the meridional transverse dimension is at least 0.05. The working distance is at least 270 mm. This can yield an imaging optical unit, the use of which is relatively manageable in a projection exposure apparatus, such as for EUV projection lithography.

A catoptric system having a reference axis and first, second, and third reflectors. The first reflector contains a pattern-source carrying a substantially one-dimensional pattern. A combination of the second and third reflectors is configured to form an optical image of the pattern, with a demagnification coefficient N>1 in extreme UV light, and with only two beams of light that have originated at the first reflector as a result of irradiation of the first reflector with light incident upon it. An exposure apparatus employing the catoptric system and method of device manufacturing with the use of the exposure apparatus.

There is provided a projection optical system that projects an image of an object onto an image plane. The projection optical system includes an imaging optical system including a first concave mirror, a convex mirror, and a second concave mirror; an optical member having a first reflecting surface and a second reflecting surface each redirecting an optical path; and a supporting member that supports the convex mirror. The first reflecting surface, the first concave mirror, the convex mirror, the second concave mirror, and the second reflecting surface are provided in that order in a direction of travel of light from an object plane. The optical member has a through hole having an opening on a side facing the convex mirror. The supporting member extends through the through hole and from the opening to the convex mirror.

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.

A projection lens of an EUV-lithographic projection exposure system with at least two reflective optical elements each comprising a body and a reflective surface for projecting an object field on a reticle onto an image field on a substrate if the projection lens is exposed with an exposure power of EUV light, wherein the bodies of at least two reflective optical elements comprise a material with a temperature dependent coefficient of thermal expansion which is zero at respective zero cross temperatures, and wherein the absolute value of the difference between the zero cross temperatures is more than 6K.

There is provided a reflective image-forming optical system which is applicable to an exposure apparatus using, for example, EUV light and which is capable of increasing numerical aperture while enabling optical path separation of light fluxes. In a reflective imaging optical system (6) forming an image of a first plane (4) onto a second plane (7), the numerical aperture on a side of the second plane with respect to a first direction (X direction) on the second plane is greater than 1.1 times a numerical aperture on the side of the second plane with respect to a second direction (Y direction) crossing the first direction on the second plane. The reflecting imaging optical system has an aperture stop (AS) defining the numerical aperture on the side of the second plane, and the aperture stop has an elliptic-shaped opening of which size in a major axis direction (X direction) is greater than 1.1 times that in a minor axis direction (Y direction).

An assembly and method for separating first radiation and second radiation in the far field, wherein the first radiation and the second radiation have non-overlapping wavelengths, The assembly comprises a capillary structure, wherein the first radiation and the second radiation propagate coaxially along at least a portion of the capillary structure, and an optical structure configured to control the spatial distribution of the first radiation outside of the capillary structure, through interference, such that the intensity of the first radiation in the far field is reduced along an optical axis of the second radiation.