Patent ID: 8339701

Claim:
An immersion projection optical system which images a pattern provided in an object surface of the immersion projection optical system onto an image surface of the immersion projection optical system, comprising: a first lens unit including at least two lenses; a mirror group including two mirrors, arranged between the first lens unit and the image surface; a second lens unit, arranged between the mirror group and the image surface, including at least one lens; a third lens unit, arranged between the second lens unit and the image surface, including at least two negative lenses; and a fourth lens unit, arranged between the second lens unit and the image surface, including a liquid immersed optical element which is in contact with a liquid and a plurality of lenses between the third lens unit and the liquid immersed optical element, wherein a maximum diameter of the fourth lens unit is larger than a maximum diameter of the third lens unit, wherein the immersion projection optical system includes only two mirrors, and wherein every transmitting member and every mirror constituting the projection optical system is arranged along a single straight optical axis, wherein the immersion projection optical system is an unobscured system having no pupil obscuration and the immersion projection optical system forms exactly two intermediate images between the object surface and the image surface.