Patent ID: 7586113

Claim:
An illumination system, comprising: a collector configured to concentrate the EUV radiation emitted by a source by reflection in the direction of an optical axis, along which the EUV radiation is guided by successive optical elements, a first optical element configured to generate secondary light sources in the illumination system, a second optical element at the location of the secondary light sources, the second optical element configured to guide the EUV radiation, reflected by the first optical element, along the optical axis, and the second optical element configured to image the first optical element into the illumination field arranged in an image plane which coincides with the object surface, wherein: a maximum of five reflecting elements are arranged between the collector and the illumination field; the optical axis meets the reflecting optical elements at an angle of incidence which is either greater than 60° or less than 30°, an axis angle of deflection between a source axis portion of the optical axis, which runs between the collector and the first optical element, or of the projection of this source axis portion of the optical axis onto an illumination main plane, which lies vertically on the image plane, and in which a field axis portion, which with the image plane encloses an angle less than 90°, of the optical axis runs between the last element of the optical device and the illumination field, and the field axis portion of the optical axis or a projection of the field axis portion of the optical axis onto the illumination main plane is greater than 30°; and at least an axis portion of the optical axis is inclined between at least two of the optical elements relative to the illumination main plane.