Position detecting method and apparatus

摘要

A method of detecting relative positional deviation between first and second objects. The method includes the steps of providing the first object with a first mark which functions as a lens, providing the second object with a second mark which functions as a lens, providing an optical system between the first and second objects, directing a radiation beam through the first mark and the optical system to the second mark, and detecting any shift of the radiation beam from the second mark irradiated with the radiation beam from the optical system, to detect the relative positional deviation of the first and second objects.