Method and apparatus for inspecting optical device

An inspection apparatus for an optical device comprising:

• a diffraction element disposed on an optical path of a light flux passed through the optical device;
• and
• a detection unit of which an incident surface is disposed on an optical path of diffraction light generated from the diffraction element to detect an intensity of interference light between the diffraction light and the light flux which is not diffracted but is passed through the optical device at a measurement point on a predetermined plane perpendicular to an optical axis of the optical device and to obtain periodical variation thereof, and the detection unit obtains intensity of the interference light in order to obtain information regarding a wavefront of the light flux.

An exposure apparatus which transfers a pattern onto an object through a projection optical system, comprising:

• a diffraction element disposed on a optical path of illumination light having an exposure wavelength passed through the projection optical system;
• and
• a detection unit of which an incident surface is disposed on a light path of a diffraction light generated from the diffraction element to detect an intensity of interference light between the diffracting light and the illuminating light which is not diffracted but is passed through the projection optical system at a measurement point on a predetermined plane perpendicular to an optical axis of the projection optical system to obtain periodical variation thereof, and the detection unit obtains phase difference information on the basis of the variation of the intensity of the interference light in order to obtain information regarding a wavefront of the illumination light.