Patent ID: 7053986

Claim:
A projection optical system for projecting an image of a first object onto a second object, said projection optical system comprising: a first imaging optical system that forms a first intermediate image of the first object, and is a refractive optical system; a second imaging optical system that forms a second intermediate image of the first object, and includes two mirrors; and a third imaging optical system that forms an image of the first object onto the second object, and includes a lens, wherein the first, second and third imaging optical systems are arranged along an optical path from the first object in this order, and wherein 0.80<|β 1 ·β 2 |<2.0 is met where β 1 is a paraxial magnification of the first imaging optical system, and β 2 is a paraxial magnification of the second imaging optical system, wherein one of the two mirrors is a concave mirror, and wherein said first imaging optical system and said concave mirror have a common straight optical axis.