Projection optical system, exposure apparatus, and exposure method

A projection optical system which projects a reduced image of a pattern disposed on a first plane with light from the pattern onto a second plane through liquid, the projection optical system comprising:

• a refractive optical element having a light emitting surface, through a part of which the light passes in use, the light emitting surface being arranged so as to contact the liquid which is disposed in an optical path of the light from the light emitting surface in use,
• wherein the projection optical system projects the reduced image in a projection region on the second plane, a center of the projection region being decentered from an optical axis of the projection optical system with respect to one of a first direction and a second direction which are perpendicular to each other and are perpendicular to the optical axis;
• wherein the refractive optical element has a protruding portion formed in an second plane side of the refractive optical element so as to protrude toward the second plane with respect to a different portion of the refractive optical element from the protruding portion;
• and
• wherein the protruding portion is formed so that a center of the light emitting surface is decentered from the optical axis with respect to the one of the first and second directions.