| 摘要 |
<p>Disclosed is a method for measuring wavefront information about a projection optical system, wherein a first diffraction grating having a pitch P1 is disposed on the object plane side of the projection optical system, a second diffraction grating having a pitch P2 which is half the pitch of the image formed by the projection optical system of the first diffraction grating is disposed on the image plane side of the projection optical system (PL), the first diffraction grating is illuminated by illuminating light, the interference fringes of the shearing interference light beam composed of the two pairs of diffraction light beams formed by the illuminating light through the first diffraction grating, the projection optical system, and the second diffraction grating are received, and wavefront information about the projection optical system is acquired on the basis of the received interference fringes. The wavefront information about the projection optical system can be measured with high accuracy.</p> |
