US Patent 7602504 Exposure apparatus and device manufacturing method

An exposure apparatus, which equipped with a projection optical system that is configured to project a pattern of an original onto a substrate, includes an interferometer configured to measure a wavefront in a first direction and a wavefront in a second direction of light passed through the projection optical system; a focus detecting unit configured to detect focus positions in the first and second directions of the projection optical system; and a calculating unit configured to calculate wavefront aberration of the projection optical system on the basis of the measurement result of the interferometer and the detection result of the focus detecting unit.