Patent ID: 8743342

Claim:
An exposure optical system comprising: an illumination optical system configured to illuminate a pattern arranged on a first plane with a light from a light source; and a reflective imaging optical system configured to project an image of the pattern onto a photosensitive substrate arranged on a second plane, wherein the reflective imaging optical system includes an incident pupil positioned on a side opposite to the reflective imaging optical system such that: the first plane is located between the incident pupil and the reflective imaging optical system; and a condition of −14.3<(PD/TT)/R←8.3 is fulfilled, where PD represents a distance along an optical axis between the incident pupil and the first plane, TT represents a distance along the optical axis between the first-plane and the second plane, and R represents an angle of incidence (rad) of a main light beam incident on the first plane: and wherein the illumination optical system includes a plurality of first reflecting optical elements arranged in parallel and positioned on the incident pupil, and the illumination optical system superimposes a plurality of light beams on the first plane, the plurality of light beams being generated by reflection of the light by the first reflecting optical elements.