Patent ID: 6844919

Claim:
A projection optical system having an image side numerical aperture that is greater or equal to 0.75, and which forms an image of a first object upon a second object using light of a predetermined wavelength less than or equal to 300 nm, comprising: plural optical groups having at least one lens; and a distance D in mm along an optical axis between an optical surface closest to the second object, and the second object, satisfies a condition of 0.1<D<5, wherein the plural optical groups comprise: a first optical group, arranged in an optical path between the first surface and the second object, having a negative power; a second optical group, arranged in an optical path between the first optical group and the second object, having a positive power; a third optical group, arranged in an optical path between the second optical group and the second object, having a negative power; a fourth optical group, arranged in an optical path between the third optical group and the second object, having a positive power; and a fifth optical group, arranged in an optical path between the fourth optical group and the second object, having a positive power.