Patent ID: 7283294

Claim:
A catadioptric optical system comprising: a first imaging optical system including a concave mirror and forming an intermediate image of a first object, said first imaging optical system forming a reciprocating optical system that an incidence light and reflected light pass; a second imaging optical system for forming an image of the intermediate image onto a second object; a first optical path deflective member, provided between the concave mirror and the intermediate image, for introducing a light from the first imaging optical system to the second imaging optical system; a second optical path deflective member provided between the intermediate image and the second object; a lens unit, provided between the intermediate image and the second optical path deflective member, wherein said first optical path deflective member deflects a light in such a direction that a forward path of the first imaging optical system intersects a return path of the first imaging optical system, wherein said intermediate image is formed without an optical element after a deflection, and wherein 6.80<|β1·βf/NAO|<10.60, is met, where β 1 is a paraxial imaging magnification of the first imaging optical system, NAO is a numerical aperture of the light at the first object side, and βf is a paraxial imaging magnification of the lens unit.