Illumination optical system, exposure apparatus having the same, and device fabricating method

摘要

An illumination optical system for illuminating a reticle using light from a light source includes an illumination-light generating mechanism for generating a light amount distribution on a plane that has a substantially Fourier conversion relationship with the reticle while making variable a ratio of a light amount between a first area and a second area different from the first area, the first and second areas being on the plane.