| 摘要 |
PURPOSE:To enable an excellent reticle pattern to be transferred to a picture extending to the whole region by providing a variable opening diameter diaphragm in light emitting system or light detecting system. CONSTITUTION:A variable opening diameter diaphragm 17 is arranged so that three planes i.e. a plane perpendicular to an optic axis of a lighting lens 8 as well as passing through the center of the lens 8, another plane including the variable opening diameter diaphragm 17 and a reference plane optimizing the focus of a reticle pattern may be intersected in a straight line. The diaphragm 17, the lighting lens 8 and a wafer 2 are arranged to meat said requirements. Through these procedures, when a picture is focussed without defocussing the opening of diaphragm 17 on the wafer 2, if the lighting conditions of the opening of diaphragm 17 are even, the intensities of light flux in the lighting region E of detecting light on the wafer 2 can be made even. |
