Method and apparatus for measuring wavefront, and exposure method and apparatus

Abstract

A method for measuring wavefront information of a projection optical system includes arranging a first diffraction grating having a pitch P1 on a side of an object plane of the projection optical system; arranging a second diffraction grating having a pitch P2 which is ½ of a pitch of an image of the first diffraction grating formed by the projection optical system, on a side of an image plane of the projection optical system PL; illuminating the first diffraction grating with an illumination light; receiving interference fringes of a shearing interference light composed of two pairs of diffracted lights formed by the illumination light from the second diffraction grating via the first diffraction grating and the projection optical system; and determining the wavefront information of the projection optical system based on the received interference fringes. The wavefront information of the projection optical system can be measured highly accurately.

Dependencies are inferred from the claim text.