| 摘要 |
PURPOSE:To enable a laser light and an illuminating light to be effectively utilized for their respective purposes by providing a dichroic beam splitter and separating the laser light and the illuminating light that pass a common objective lens from each other. CONSTITUTION:A laser light (a) set to become a P-polarized light, after reflected from a rotary polygonal mirror 3, is transmitted through a dichroic beam splitter 50 and a polarization beam splitter 51, scans a mask 12 via an objective lens 11, passes an imaging optical system 40 and reflected from a wafer 13. On the other hand, the illuminating light (b) for a visual observation system, polarized by a polarizing plate 52 to become an S-polarized light, reaches the mask 12 and reflected by the wafer 13 except the reflected light from its reverse side surface. After both the laser light and illuminating light reflected from the wafer 13 pass a quarter-wavelength plate 41, the laser light (a) is S-polarized and, after reflected from the splitter 51, incident upon a potoelectric detector 18 system and the illuminating light (b) is P-polarized, transmitted through the splitter 51 and, after reflected by the splitter 51, incident upon an optical system 22. Thus, a plurality of kinds of illuminating light can be effectively utilized for plural purposes. |
