Optical element with at least one electrically conductive region, and illumination system with the optical element

An illumination system having an optical path configured to illuminate an exit pupil in an exit pupil plane of the illumination system, the illumination system comprising:

• an optical element comprising:
• a first region that transmits or reflects light;
• and
• a second region that is at least partially electrically conductive to produce an electrical current when exposed to EUV radiation,
• wherein:
• the second region is separated from the first region;
• the second region is electrically insulated from the first region;
• the second region at least partially surrounds the first region;
• and
• the optical element is positioned along an optical path of the illumination system upstream of the exit pupil of the illumination system.

A projection objective configured to an object in an object plane along an optical path to an image in an image plane, the projection objective comprising:

• an optical element, comprising:
• a first region that reflects or transmits light;
• and
• a second region that is at least partially electrically conductive to produce an electrical current when exposed to EUV radiation,
• wherein:
• the second region is separated from the mirror facet;
• the region is electrically insulated from the first region;
• the second region at least partially surrounds the first region;
• and
• the optical element is positioned in the optical path of the projection objective.