Optical element, and assembly and optical system therewith

An optical element configured to be used in a holding device of an assembly of an optical system of a microlithographic projection exposure apparatus, the optical element comprising:

• a body which is transparent to used light in a used wavelength range;
• wherein:
• the body comprises a first light passage surface and an opposing second light passage surface;
• each of the first and second light passage surfaces comprises an optical used region and an edge region outside the optical used region;
• the optical used region of each of the first and second light passage surfaces is configured to be disposed in a beam path of the used light in the optical system;
• the edge region of each of the first and second light passage surfaces is configured to engage a holding element of the holding device;
• the optical used region of each of the first and second light passage surfaces is of optical quality;
• the optical used region of each of the first and second light passage surfaces comprises a surface shape configured in accordance with a used region specification specified by a function of the optical element in the beam path of the used light in the optical system;
• the edge region of the first light passage surfaces comprises light deflection structures comprising a geometrically defined surface in accordance with an edge region specification which deviates from the used region specification, the geometrically defined surface being configured to deflect portions of light deflected by the light deflection structures into a target region outside of the beam path of the used light in the optical system;
• and
• a plurality of contact zones are distributed over a circumference of the edge region of the second light passage surface;
• the light deflection structures to deflect portions of light into a target region outside of the contact zones;
• and
• at least one of the following conditions applies to the light deflection structures:
• (i) for the first deflection surface, the edge region specification and the used region specification of are configured so that the surface shape of the used region in a transition region located outside of the used region in the edge region transitions smoothly into the surface shape of the edge region;
• (ii) the first light passage surface has a continuously curved aspheric surface shape in the edge region in accordance with the edge region specification and a spherical surface shape or an aspherical surface shape in the optical used region in accordance with the used region specification;
• (iii) the light deflection structures have, in an entire edge region of the first light passage surface, a continuously curved surface shape with a negative radius of curvature in at least one region;
• and
• (iv) within the edge region of the first light passage surface, there is an inflection point region with a transition from a positive radius of curvature on a side of the optical used region to a negative radius of curvature at a distance from the optical used region.