| 摘要 |
A method and illumination optical system forms a modified illumination configuration on an optical integrator so that a secondary light source having a desired modified illumination configuration is formed and light loss is minimized. A light beam shape changing element that diffuses illumination in a plurality of directions, and an angular light beam forming element that forms a plurality of light source images operate together to create a modified illumination configuration on the optical integrator. Since the secondary light source has a desired modified illumination configuration, an aperture stop used to restrict the size and/or shape of the secondary light source blocks only a small amount of illumination, or can be eliminated altogether. It is possible to alter the annular ratio and outer diameter of an annular or quadrupole modified illumination configuration by changing the magnification of a zoom optical system positioned between the light beam shape changing element and the angular light beam forming element. Furthermore, by changing the focal length of a zoom optical system (which is positioned upstream of the optical integrator), it is possible to change the outer diameter of the annular or quadrupole secondary light source without changing the annular ratio thereof.
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