Patent ID: 7385672

Claim:
An exposure apparatus comprising: a projection optical system for projecting a pattern of a reticle onto an object to be exposed, using exposure light; an optical element for determining a shape of an effective light source on a plane that has a Fourier transformation relationship with the reticle; a light detector for detecting the shape of the effective light source and a light intensity of the exposure light on image plane of the projection optical system; and a controller for changing performance of the projection optical system, wherein the light detector detects the first light intensity on an image plane of the projection optical system when the reticle is not arranged at an object plane of the projection optical system, and the second light intensity on the image plane of the projection optical system when the reticle is arranged at the object plane of the projection optical system, and wherein the controller changes the performance of the projection optical system based on the shape of the effective light source, the first light intensity and the second light intensity detected by the light detector.