Patent ID: 6531706
Filing Date: 2003-03-11
Classification: G03F

Abstract:
A surface position detecting system comprising:surface position detecting means including light projecting means for projecting light obliquely onto a detection point; and light receiving means for receiving reflection light from the detection point, wherein, while an object having a region with a pattern structure is relatively scanned relative to said surface position detecting means, a surface position at plural points within the region is detected, wherein said surface position detecting system comprises: optimum value detecting means for projecting, before the surface position detection, light from said light projecting means to each of the plural detection points and for receiving, with said light receiving means, reflection light from the point, said optimum value detecting means detecting and memorizing an optimum value of a gain of said light receiving means or a drive current for said light projecting means with respect to each detection point, on the basis of a light reception signal of said light receiving means; and setting means for setting an optimum value for a drive current for said light projecting means or a gain of said light receiving means with respect to each of the detection points, for the surface position detection.