Patent ID: 6888618

Claim:
A scan type exposure apparatus wherein a pattern of an original is lithographically transferred to a substrate sequentially while the original and the substrate are scanningly moved relative to exposure light, said apparatus comprising: an illumination optical system for illuminating an original with exposure light output from a light source; a projection optical system for projecting a pattern of the original, illuminated by the illumination optical system, onto a substrate; a photodetector disposed in said illumination optical system and at a position optically conjugate with the original, for detecting a quantity of light illuminating the original; control means for controlling the exposure light output from the light source on the basis of the output of the photodetector; and correcting means for reducing an influence of reflection light from the original, on the basis of the output of the photodetector as the original is illuminated by the illumination optical system, while excluding influence of a reflection light component.