Patent ID: 7466395

Claim:
An exposure apparatus comprising: a projection optical system that projects a pattern image of a reticle onto an object to be exposed; and a shearing interferometer configured to measure an optical characteristic of the projection optical system, wherein the shearing interferometer includes: a mask placed on an object plane side of the projection optical system, the mask shaping a wavefront of light emitted from a light source into a spherical wavefront; a detector configured to detect the light passing through the projection optical system; an optical element placed between the mask and the projection optical system or between the projection optical system and the detector, the optical element has a splitting surface configured to split light from the mask into a reflected beam and a transmitted beam; and a reflecting surface adapted to reflect the reflected beam, wherein the detector detects interference fringes formed by interference between a first light beam and a second light beam, the first light beam being transmitted by the splitting surface and the projection optical system without being reflected by the splitting surface, the second light beam being transmitted by the splitting surface and the projection optical system after being reflected by the splitting surface and the reflecting surface.