Double-facetted illumination system with attenuator elements on the pupil facet mirror

An illumination system configured to illuminate an object in a field plane with radiation from a light source, the illumination system comprising:

• a first facetted optical element in a first plane comprising at least a first field raster element and a second field raster element, the first and second field raster elements being configured to receive light from the light source during operation of the system and divide the received light into a first bundle of light and a second bundle of light;
• an optical component comprising at least a second facetted optical element in a second plane, the second facetted optical element comprising a first pupil raster element and a second pupil raster element;
• an attenuator arranged in or close to the second plane or a plane conjugated to the second plane, the attenuator being arranged at least in a path of the first light bundle between the first field raster element and the first pupil raster element,
• wherein during operation of the illumination system the light source emits radiation having a wavelength of 193 nm or less, the first light bundle impinges upon the first pupil raster element and the second light bundle impinges upon the second pupil raster element, the optical component images the first and second field raster elements to the field plane, and the first light bundle has a first cross section and the attenuator vignettes at least a first area of the first cross section of the first light bundle.

An illumination system configured to illuminate an object in a field plane with radiation from a light source, the illumination system comprising:

• a first facetted optical element in a first plane comprising at least a first field raster element and a second field raster element, the first and second field raster elements being configured to receive light from the light source during operation of the system and divide the received light into a first bundle of light and a second bundle of light;
• an optical component comprising at least a second facetted optical element in a second plane, the second facetted optical element comprising a first pupil raster element and a second pupil raster element;
• an attenuator arranged in or close to the second plane or a plane conjugated to the second plane, the attenuator being arranged at least in a path of the first light bundle between the first field raster element and the first pupil raster element,
• wherein during operation of the illumination system the light source emits radiation having a wavelength of 193 nm or less, the first light bundle impinges upon the first pupil raster element and the second light bundle impinges upon the second pupil raster element, the object is scanned in a scanning direction in the field plane, and the optical component images the first and second field raster elements to a field in the field plane such that a telecentricity error at the field plane does not exceed ±0.5 mrad across the field in a direction perpendicular to the scanning direction.