Patent ID: 7233009

Claim:
A lithographic projection apparatus, comprising: an illumination system configured to form a beam of radiation from radiation provided by a radiation source; a support configured to hold a patterning device which is to be irradiated by the beam of radiation to pattern the projection beam; a substrate table configured to hold a substrate; a projection system configured to image an irradiated portion of the patterning device onto a target portion of the substrate; and a reflector assembly placed in the vicinity of the source or an image of the source, the reflector assembly comprising an inner and an outer reflector extending in a direction of an optical axis on which the source or an image of the source is located, the inner reflector being closer to the optical axis than the outer reflector, the inner and outer reflectors each having an inner reflective surface and an outer backing layer, the inner reflective surface of the outer reflector facing the backing layer of the inner reflector, the backing layer of the inner reflector being covered with a reflective layer having a reflectivity of between 0.7 and 0.99 for wavelengths between 0.1 and 100 μm.