Polarization-modulating element, illumination optical apparatus, exposure apparatus, and exposure method

An illumination optical apparatus which illuminates an object having a pattern with illumination light, the illumination optical apparatus comprising:

• a polarization-modulating element made of an optical material having optical activity, which is arranged in an optical path of the illumination light and which changes a polarization state of the illumination light incident on the polarization-modulating element into a predetermined polarization state based on the optical activity of the optical material, the polarization-modulating element having a circumferentially varying thickness profile;
• an annular ratio changing optical system, arranged in the optical path of the illumination light, that changes an annular ratio of a light intensity distribution formed on an illumination pupil of the illumination optical apparatus;
• and
• an optical integrator arranged in the optical path of the illumination light so that a rear focal plane of the optical integrator is substantially coincident with the illumination pupil,
• wherein the polarization-modulating element is arranged between the annular ratio changing optical system and the optical integrator, and
• wherein the circumferentially varying thickness profile is formed to change a linearly polarized state of the illumination light having a polarization direction substantially along a single direction into an azimuthal polarized state having a polarization direction substantially along a circumferential direction on the illumination pupil.