Patent ID: 7573563

Claim:
An exposure apparatus for exposing a pattern of a reticle onto a plate using light from a light source, said exposure apparatus comprising: an illumination optical system for illuminating the reticle using the light from the light source; a projection optical system for projecting the pattern of the reticle onto the plate; and a measuring unit for measuring three variables that consist of a pair of amplitudes of two orthogonal directions and a phase difference between the pair of amplitudes, and that are used to express a polarization state of the light from an object to be measured that is the illumination optical system or the projection optical system, the measuring unit being provided on an optical path of the light subsequent to the object to be measured and being not provided on the optical path between the light source and the object to be measured, the measuring unit including: an optical unit for providing at least three phase difference to the light that has passed at least part of the object to be measured; a polarization element for providing a different transmittance in accordance with the polarization state of the light that has passed the optical unit; and an image pickup device for detecting an intensity of the light that has passed the polarization element, wherein the optical unit includes a phase shifter and a rotating unit for rotating the phase shifter at least to a first rotating angle of θ°, a second rotating angle of (θ+α)°, and a third rotating angle of (θ+α+90)°, where α° ranges between 32° and 39°, and the phase difference ranging between 130° and 150° when the optical unit is rotated to any one of the first, second, and third rotating angle.