Patent ID: 7515248

Claim:
A method for adjusting an illumination optical system that illuminates an illuminated surface with light including a predetermined polarized state supplied from a light source, comprising: a wavelength plate setting step of (i) setting a quarter-wave plate in an illumination light path of the illumination optical system such that a crystal optic axis of the quarter-wave plate is set at a predetermined angular position, and (ii) setting a half-wave plate in the illumination light path such that a crystal optic axis of the half-wave plate is set at a predetermined angular position, wherein based on a result of detection of a polarized state of the light in the light path between a polarized state switching device and the illuminated surface when the crystal optic axes of the quarter-wave plate and the half-wave plate are respectively changed, the wavelength plate setting step sets (1) the crystal optic axis of the quarter-wave plate at a desired position for converting incident elliptically polarized light into linearly polarized light, and (2) the crystal optic axis of the half-wave plate at a standard position for converting incident linearly polarized light into linearly polarized light that includes a polarized plane in a predetermined direction, wherein the crystal optic axis of the quarter-wave plate is set at a first angular position, at which a contrast for changes in an S 1 component of a Stokes parameter becomes substantially maximum in the detection result, and the crystal optic axis of the half-wave plate is set at a second angular position, at which the S 1 component of the Stokes parameter becomes substantially maximum or substantially minimum in the detection result while the crystal optic axis of the quarter-wave plate is set at the first angular position.