Patent ID: 7436589

Claim:
A reflective-type projection optical system for forming a reduced image of a first surface on a second surface, the optical system comprising: a first reflective imaging optical system for forming an intermediate image of the first surface and a second reflective imaging optical system for forming an image of the intermediate image on the second surface; the first reflective imaging optical system comprising, from the first surface side in order of light beam incidence, a first reflective mirror, a second reflective mirror, a third reflective mirror, and a fourth reflective mirror; the second reflective imaging optical system comprising, from the first surface side in order of light beam incidence, a fifth reflective mirror, a sixth reflective mirror, a seventh reflective mirror, and an eighth reflective mirror, and at least one of the reflective surfaces of the reflective mirrors being configured as a spherical surface, and the remaining reflective surfaces of the mirrors being configured as aspheric surfaces, wherein the following condition is satisfied: 8 <TT/H 0<15 when the axial interval between the first surface and the second surface is TT and the maximum object height on the first surface is H 0 .