Patent ID: 6714280
Filing Date: 2004-03-30
Classification: G02B,G03F

Abstract:
A projection optical system capable of projecting to an image space an image of an object in an object space, the system comprising:a) at least one first refractive optical member comprising a first fluoride substance; and b) at least one second refractive optical member comprising a second fluoride substance; c) wherein MX1 is greater than MX2; and d) the design condition 0.4<MX2MX1<0.87â€ƒis satisfied; e) where MX1 is the effective aperture of the surface or surfaces having the largest effective aperture among the surface or surfaces of the first refractive optical member or members; and f) MX2 is the effective aperture of the surface or surfaces having the largest effective aperture among the surface or surfaces of the second refractive optical member or members.