An exposure apparatus for exposing a substrate to light via an original
plate. A projection optical system projects a pattern of the original
plate onto the substrate, a liquid immersion mechanism generates a liquid
immersion state in which a gap between the final surface of the
projection optical system and the substrate is filled with liquid, a
first photosensor detects light which has passed through the projection
optical system, a second photosensor, different from the first
photosensor, detects light that has passed through the projection optical
system, and a controller calibrates an output from the first photosensor
in the liquid immersion state based on a first output from the first
photosensor in the liquid immersion state, a second output from the first
photosensor in a non-liquid immersion state, and a third output from a
reference illuminometer.