Patent ID: 7349065

Claim:
An exposure apparatus comprising: an illumination optical system for illuminating, in a slit-shaped illumination area, a pattern of a reticle with exposure light from an exposure light source; a projection optical system for projecting an image of the pattern onto a wafer, said projection optical system including a mirror; a detection system for detecting a positional offset of a light spot while the wafer is exposed with the image; and a drive unit for driving an optical element of the projection optical system, while the wafer is exposed with the image based on the positional offset detected by the detection system, wherein said detection system includes a detection light source for emitting a detection light, and a light-receiving device for receiving the light spot of the detection light via the projection optical system, and wherein the detection light source is located at a position substantially equivalent to the wafer, the light-receiving device is located at a position substantially equivalent to the reticle, and the detection light source emits the detection light from the outside of the image.