Optical apparatus, exposure apparatus and exposure method

An exposure method to expose a substrate by causing modulated light to be incident on the substrate, comprising:

• interposing an optical apparatus in an optical path of the light, the optical apparatus shifting the light in a predetermined shift direction orthogonal to a traveling direction of the light;
• moving the substrate relative to an incident position of the light emitted from the optical apparatus;
• and
• causing the light to be incident on the substrate while adjusting a shift amount of the light by the optical apparatus,
• wherein the optical apparatus includes:
• a shift optical element which is a plane parallel plate having a one-side surface on which input light is incident and an other-side surface from which output light is emitted, which are surfaces parallel to each other;
• and
• a correction optical element which is arranged on the optical path of the input light or the optical path of the output light and corrects an astigmatic difference appearing in the output light, and
• the optical apparatus rotates the shift optical element and displaces the correction optical element in conjunction with the shift optical element, to thereby adjust the shift amount.