A gamma ray generator includes a rotational shaft, a plurality of holders and a plurality of gamma ray sources. The holders are connected to the rotational shaft. The gamma ray sources are disposed in the holders respectively, wherein the holders respectively have an upper portion and a lower portion connecting to the upper portion, and the gamma ray source is placed at an interface between the upper portion and the lower portion.

A mirror, in particular for a microlithographic projection exposure apparatus has an optically effective surface (11), a mirror substrate (12), a reflection layer stack (21) for reflecting electromagnetic radiation that is incident on the optical effective surface, and at least two piezoelectric layers (16a, 16b, 16c), which are arranged successively between the mirror substrate and the reflection layer stack in the stack direction of the reflection layer stack and to which an electric field can be applied to produce a locally variable deformation, wherein at least one intermediate layer (22a, 22b) made of crystalline material is arranged between the piezoelectric layers (16a, 16b, 16c), wherein the intermediate layer is designed to leave an electric field, which is present in the region of the piezoelectric layers (16a, 16b, 16c) that adjoin the intermediate layer (22a, 22b) in the stack direction of the reflection layer stack (21), substantially uninfluenced.

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.

A method of manufacture of an extreme ultraviolet reflective element includes: providing a substrate; forming a multilayer stack on the substrate, the multilayer stack includes a plurality of reflective layer pairs having a first reflective layer and a second reflective layer for forming a Bragg reflector; and forming a capping layer on and over the multilayer stack, the capping layer formed from titanium oxide, ruthenium oxide, niobium oxide, ruthenium tungsten, ruthenium molybdenum, or ruthenium niobium, and the capping layer for protecting the multilayer stack by reducing oxidation and mechanical erosion.

There is provided a diffractive waveguide device comprising: a light source, at least one light detector, an SBG device comprising a multiplicity of separately switchable SBG elements sandwiched between transparent substrate to which transparent electrodes have been applied. The substrates function as a light guide. Each SBG element encodes image information to be projected on an image surface. Each SBG element when in a diffracting state diffracts light out of the light guide to form an image region on an image surface. The light detector detects light scattered from an object disposed in proximity to the image surface and illuminated by said image region.

An optical element (1) for reflecting EUV radiation (4) includes: a substrate (2); a coating (3) applied to the substrate (2), which coating reflects the EUV radiation (4); a top layer (5) protecting the reflective coating (3), which top layer is applied to the reflective coating (3); and an intermediate layer (6) having at least one reactive material (7) which, together with an activating gas (O2) penetrating through a gap (5a) in the top layer 95), forms at least one reaction product (8) sealing the gap (5a). A related EUV lithography system has at least one such reflective optical element (1), and a related method for sealing a gap (5a) in the top layer (5) of such an optical element (1) are also disclosed.

An EUV reflective structure includes a substrate and multiple pairs of a Si layer and a Mo layer. The Si layer includes a plurality of cavities.

A mirror, in particular for a microlithographic projection exposure apparatus, has an optically effective surface (10a), a mirror substrate (11) and a reflection layer stack (12) configured to reflect electromagnetic radiation that is incident on the optically effective surface. A metallic diffusion barrier layer (13) is arranged on that side of the reflection layer stack which faces toward the optically effective surface, and a stabilization layer (14) is arranged on the side of the diffusion barrier layer that faces toward the optically effective surface (10a). The stabilization layer reduces deformation of the diffusion barrier layer compared to an analogous structure without such a stabilization layer upon irradiation of the optically effective surface with electromagnetic radiation. The stabilization layer has a porosity, a relative density of which is no more than 80%, where the relative density is defined as the ratio between geometric density and true density.

A film element of an EUV-transmitting wavefront correction device is arranged in a beam path and includes a first layer of first layer material having a first complex refractive index n.sub.1=(1−δ.sub.1)+iβ.sub.1, with a first optical layer thickness, which varies locally over the used region in accordance with a first layer thickness profile, and a second layer of second layer material having a second complex refractive index n.sub.2=(1−δ.sub.2)+iβ.sub.2, with a second optical layer thickness, which varies locally over the used region in accordance with a second layer thickness profile. The first and second layer thickness profiles differ. The deviation δ.sub.1 of the real part of the first refractive index from 1 is large relative to the absorption coefficient β.sub.1 of the first layer material and the deviation δ.sub.2 of the real part of the second refractive index from 1 is small relative to the absorption coefficient β.sub.2 of the second layer material.

An optical element for transmitting radiation includes: a first surface region surrounding an optically used area of the optical element; and a second surface region that adjoins the first surface region. A circumferential edge is formed between the first and second surface regions. The optical element further includes a one-piece film which covers the first surface region, the edge and the second surface region. The film includes a hydrophobic material at least on its side facing away from the first and the second surface regions. An optical assembly includes at least one such optical element. A method produces such an optical element.