Abstract: A mirror (1a; 1a?; 1b; 1b; 1c; 1c?) with a substrate (S) and a layer arrangement configured such that light (32) having a wavelength below 250 nm and incident on the mirror at at least an angle of incidence of between 0° and 30° is reflected with more than 20% of its intensity. The layer arrangement has at least one surface layer system (P??) having a periodic sequence of at least two periods (P3) of individual layers, wherein the periods (P3) include a high refractive index layer (H??) and a low refractive index layer (L??). The layer arrangement has at least one graphene layer. Use of graphene (G, SPL, B) on optical elements reduces surface roughness to below 0.1 nm rms HSFR and/or protects the EUV element against a radiation-induced volume change of more than 1%. Graphene is also employed as a barrier layer to prevent layer interdiffusion.

Abstract: A method for repairing optical elements having a coating, in which the coating is fully or partially removed or left on the optical element, a polishing layer being provided in the coating or a polishing layer being applied, which allows simple processing of the surface to achieve high geometrical accuracy and lower surface roughness. A new coating is applied onto the corresponding polishing layer. Also addressed are corresponding optical elements, including optical elements recycled according to the method.

Abstract: A mirror (1a; 1a?; 1b; 1b?; 1c; 1c?) with a substrate (S) and a layer arrangement configured such that light (32) having a wavelength below 250 nm and incident on the mirror at at least an angle of incidence of between 0° and 30° is reflected with more than 20% of its intensity. The layer arrangement has at least one surface layer system (P??) having a periodic sequence of at least two periods (P3) of individual layers, wherein the periods (P3) include a high refractive index layer (H??) and a low refractive index layer (L??). The layer arrangement has at least one graphine layer. Use of graphene (G, SPL, B) on optical elements reduces surface roughness to below 0.1 nm rms HSFR and/or protects the EUV element against a radiation-induced volume change of more than 1%. Graphene is also employed as a barrier layer to prevent layer interdiffusion.

Abstract: A method for producing an element having at least one arbitrarily freely formed surface (freeform surface) having a high accuracy of form and a low surface roughness. The freeform surface is obtained by at least one first processing step with a shaping material processing method in which at least an approximation to the desired freeform surface (target form) is effected, and at least one second step with a material processing method that smooths the surface, wherein at least during the second processing step of the smoothing material processing, the element (1) to be processed is elastically stressed by force introduction such that the freeform surface to be smoothed is processed by smoothing processes for spherical, plane or aspherical surfaces.

Abstract: A method for repairing optical elements having a coating, in which the coating is fully or partially removed or left on the optical element, a polishing layer being provided in the coating or a polishing layer being applied, which allows simple processing of the surface to achieve high geometrical accuracy and lower surface roughness. A new coating is applied onto the corresponding polishing layer. Also addressed are corresponding optical elements, including optical elements recycled according to the method.

Abstract: The invention relates to an imaging system of a microlithographic projection exposure apparatus, proposing improvements in the protection of exterior optical surfaces against contamination. In an imaging system with a projection objective that serves to project an image of a mask which can be set in position in an object plane onto a light-sensitive coating that can be set in position in an image plane, a membrane which is substantially transparent for an operating wavelength of the projection objective is arranged in such a way in relation to an exterior optical surface of the projection objective that between said optical surface and the membrane an interstitial space is formed which is designed to receive a liquid or gaseous medium.

Abstract: A method of making a fracture-resistant large-size calcium fluoride single crystal is described, which is suitable for an optical component for radiation in the far UV range. The calcium fluoride raw material for the single crystal is first melted and subsequently solidified by cooling the melt to form a single crystal. However the calcium fluoride raw material is doped with from 1 to 250, preferably 1 to 100, ppm of strontium, preferably added as strontium fluoride, and contains from 1 to 10 ppm of sodium as well as up to 100 ppm of other impurities.

Abstract: A device is used to hold an optical element, in particular one made of a crystalline material, in particular of CaF2, while the optical element is being coated, in particular by the vapor-deposition of at least one functional layer in a vacuum coating plant. The latter has a device for mounting the optical element, it being possible for the optical element to be heated in the vacuum coating plant via suitable radiation, in particular infrared radiation. An intermediate element which has a lower thermal absorption than the device for mounting the optical element is arranged between the device for mounting the optical element and the optical element.

Abstract: A method of making a fracture-resistant large-size calcium fluoride single crystal is described, which is suitable for an optical component for radiation in the far UV range. The calcium fluoride raw material for the single crystal is first melted and subsequently solidified by cooling the melt to form a single crystal. However the calcium fluoride raw material is doped with from 1 to 250, preferably 1 to 100, ppm of strontium, preferably added as strontium fluoride, and contains from 1 to 10 ppm of sodium as well as up to 100 ppm of other impurities.

Abstract: A device is used to hold an optical element, in particular one made of a crystalline material, in particular of CaF2, while the optical element is being coated, in particular by the vapor-deposition of at least one functional layer in a vacuum coating plant. The latter has a device for mounting the optical element, it being possible for the optical element to be heated in the vacuum coating plant via suitable radiation, in particular infrared radiation. An intermediate element which has a lower thermal absorption than the device for mounting the optical element is arranged between the device for mounting the optical element and the optical element.