Patent ID: 7142283

Claim:
An exposure apparatus comprising: an illumination optical system for illuminating a reticle using light from a light source, wherein said illumination optical system includes an optical integrator for forming a secondary light source from the light, and a variable stop arranged at or near a position where the secondary light source is formed, the variable stop being configured to vary an aperture diameter that defines a numerical aperture of said illumination optical system; a projection optical system for projecting a pattern on the reticle onto an object to be exposed, wherein said projection optical system includes an aperture stop arranged at a position substantially optically conjugate with the variable stop, said aperture stop defining a numerical aperture of said projection optical system; and a controller for controlling the aperture diameter of the variable stop in said illumination optical system as the aperture diameter of the variable stop varies so that an image of the secondary light source formed at or near the aperture stop can fall within the aperture diameter of the aperture stop, wherein said controller controls the aperture diameter of the variable stop so that a ratio of the numerical aperture in said illumination optical system to the numerical aperture in said projection optical system is equal to or smaller than 0.95.