| 摘要 |
PURPOSE:To obtain an optical illumination system which has less loss of the quantity of light even when a sigma value is variable by arranging a conic refracting member between the collector lens and aperture diaphragm of an optical system consisting of a secondary specular reflecting mirror, collector lens, and aperture diaphragm. CONSTITUTION:Luminous flux from a light source S is converged by the elliptic reflecting mirror and nearly collimated by a collector lens 2 to reach an optical integrator 4 consisting of a fly array lens group through the refracting member 3 having a conic convex surface 3a and a conic concave surface 3b. Its projection light illuminates a reticle R through the aperture diaphragm 5 and a condenser lens 6 and then an image of the reticle R is projected on a wafer W with prescribed magnification by a projection objective lens 10. Luminous flux in a hollow state is converged onto luminous flux on axially symmetrical basis by the refracting member 3, so even when the sigma value is variable, the loss of the quantity of light is reduced. |
