Position detecting system and device manufacturing method using the same

Abstract

A position detecting system for detecting a relative position of first and second objects placed in an optically conjugate relation with respect to a projection optical system includes a pulse light source, a photoelectric detector and a controller. The pulse light source emits pulse light for illuminating a first mark provided on the first object and a second mark provided on one of the second object and a reference plate disposed at a position equivalent to that of the second object. The photoelectric detector photoelectrically detects the first and second marks illuminated with the pulse light from the pulse light source. The controller controls the number of pulses of the pulse light from the pulse light source, in the photoelectric detection of the first and second marks through the photoelectric detector.

Dependencies are inferred from the claim text.