In certain aspects, the disclosure relates to an imaging system, particularly an objective or an illumination device of a microlithography projection-exposure apparatus having an optical axis (OA), with at least one optical element of an optically uniaxial crystal material whose optical crystallographic axis is substantially parallel to the optical axis (OA) of the imaging system and which at a working wavelength has an ordinary refractive index n.sub.o and an extraordinary refractive index n.sub.e, with the extraordinary refractive index n.sub.e being smaller than the ordinary refractive index n.sub.o; wherein the optical element is arranged in the ray path pattern in such a way that, at least for rays of the working wavelength which meet the optical element at an angle that falls within an angular range from the optical axis, the p-polarized component is reflected more strongly than the s-polarized component.