Patent ID: 7224441
Filing Date: 2007-05-29
Classification: G02B,G03F

Abstract:
1. A projection optical system for projecting a pattern on an object plane onto an image plane, said projection optical system comprising first to sixth reflective surfaces in order to reflect light from the object plane, the light from the object plane being reflected in order of the first reflective surface, the second reflective surface, third reflective surface, the fourth reflective surface, the fifth reflective surface, and the sixth reflective surface, wherein A wherein the first principal ray is a principal ray that is exited from a center of an arc-shaped illuminated area on the object plane and incident upon the first reflective surface, and the first plane normal is a plane normal to the first reflective surface at an incident position of the first principal ray that is exited from the center of the illumination area and incident upon the first reflective surface, wherein the second principal ray is a principal ray that is exited from the center of the illumination area, reflected on the first reflective surface, and incident upon the second reflective surface, and the second plane normal is a plane normal to the second reflective surface at an incident position of the second principal ray that is exited from the center of the illumination area, reflected on the first reflective surface, and incident upon the second reflective surface, and wherein the third principal ray is a principal ray that is exited from the center of the illumination area, reflected on the second reflective surface, and incident upon the third reflective surface, and the third plane normal is a plane normal to the third reflective surface at an incident position of the third principal ray that is exited from the center of the illumination area, reflected on the second reflective surface, and incident upon the third reflective surface.