Optical system of a microlithographic projection exposure apparatus

An optical system, comprising:

• a polarization-influencing arrangement comprising a first reflection surface and a second reflection surface,
• wherein:
• the first and second reflection surfaces are arranged at an angle of 0°±10° relative to each other, or the first and second reflection surfaces are arranged at an angle of 90°±10° relative to each other;
• during use of the optical system, light incident on the first reflection surface has an angle of 45°±5° relative to the first reflection surface;
• the polarization-influencing arrangement is rotatable about a rotation axis which is parallel to a light propagation direction of light incident on the first reflection surface during operation of the optical system;
• and
• the optical system is an EUV microlithographic optical system.

An optical system, comprising:

• a polarization-influencing arrangement comprising a first reflection surface and a second reflection surface,
• wherein during operation of the optical system:
• light reflected at the second reflection surface is reflected in a direction parallel to a direction of the light incident on the first reflection surface;
• light is incident on the first reflection surface with an angle of incidence that is within 5° of the Brewster angle for the first reflection surface at an operating wavelength of the optical system;
• and
• the polarization-influencing arrangement is rotatable about a rotation axis which is parallel to a light propagation direction of light incident on the first reflection surface, and
• wherein the optical system is a microlithographic optical system.