Abstract: The disclosure relates to an optical system of an illumination device of a microlithographic projection exposure apparatus, including at least one first light-conductance-increasing element having a plurality of diffractively or refractively beam-deflecting structures extending in a common first preferred direction the light-conductance-increasing element having an optically uniaxial crystal material in such a way that the optical crystal axis of the crystal material is substantially parallel or substantially perpendicular to the first preferred direction.

Abstract: The disclosure relates to an optical system of an illumination device of a microlithographic projection exposure apparatus, comprising at least one first light-conductance-increasing element having a plurality of diffractively or refractively beam-deflecting structures extending in a common first preferred direction the light-conductance-increasing element having an optically uniaxial crystal material in such a way that the optical crystal axis of the crystal material is substantially parallel or substantially perpendicular to the first preferred direction.

Abstract: A device for the low-deformation support of an optical element (2), in particular of an end plate of a lens in a projection printing system for semiconductor elements, is provided with a mount (1), the optical element (2) being connected to the mount (1) at least partly via a bonding layer which is located between the adjacent circumferential walls (4, 5) of mount (1) and optical element (2). The mount (1) is provided with at least three bearing feet (3) which are distributed over the circumference and on which the optical element (2) rests. The bonding layer is located in an annular gap (6) between the adjacent circumferential walls (4, 5) of mount (1) and optical element (2) over at least one section thereof.