Abstract: A collector optical system is provided in which radiation is collected from a radiation source and directed to an image focus. The collector optical system includes one or more mirrors, with each mirror being symmetric about an optical axis extending through the radiation source and each mirror having at least first and second reflective surfaces. The first and second reflective surfaces have a common focus, such that radiation from the source undergoes successive grazing incidence reflections at the first and second reflective surface and wherein the common focus is transversely offset by a predetermined distance ?r with respect to the optical axis.

Abstract: A collector optical system is provided in which radiation is collected from a radiation source and directed to an image focus. The collector optical system includes one or more mirrors, with each mirror being symmetric about an optical axis extending through the radiation source and each mirror having at least first and second reflective surfaces. The first and second reflective surfaces have a common focus, such that radiation from the source undergoes successive grazing incidence reflections at the first and second reflective surface and wherein the common focus is transversely offset by a predetermined distance ?r with respect to the optical axis.

Abstract: A reflective optical system, in which radiation from a radiation source is directed to an image focus or intermediate focus, including one or more mirrors (symmetric about the optical axis). Each mirror has at least first and second reflective surfaces, whereby radiation from the source undergoes successive grazing incidence reflections in an optical path at first and second reflective surfaces. The first and second reflective surfaces are formed such that the angles of incidence of the successive grazing incidence reflections at the first and second reflective surfaces are substantially equal. Each mirror may be formed as an electroformed monolithic component, wherein the first and second reflective surfaces are each provided on a respective one of two contiguous sections of the mirror. The reflective optical system may be embodied in a collector optical system for EUV lithography, or in an EUV or X-ray telescope or imaging optical system.