Mark position detection apparatus

摘要

A mark position detection apparatus has an illumination optical system for illuminating a measurement mark with illumination light and an imaging optical system for converging light reflected from the measurement mark to form an image of the measurement mark on an image pickup apparatus. The mark position detection apparatus measures a positional displacement of the measurement mark by processing an image signal obtained by the image pickup apparatus. The mark position detection apparatus has an optical element provided in the illumination optical system for compensating a difference in asymmetry of the image signal that depends on the wavelength of the illumination light.