Projection-optical systems are disclosed that reduce OoB radiation doses on the wafer while reducing deterioration of optical properties of the systems. An exemplary system includes a first reflector having a reflectance for light of a second predetermined wavelength, different from light of a first predetermined wavelength, that is less than a predetermined reflectance. The system also includes a second reflector having a reflectance for light of the second wavelength which is greater than the predetermined reflectance. When the reflectors in the system are classified as reflectors having a high percentage of overlap for the reflecting regions corresponding to two different points on the wafer, and reflectors having a low percentage of overlap for the reflecting regions, then, among the reflectors having a lower percentage of overlap for the reflecting regions, the most upstream reflector in the light path of the system is the second reflector.