Method of adjusting relative positions of two objects by using diffraction grating and control apparatus therefor

摘要

A method of adjusting a relative positional relationship between two objects uses a diffraction grating. A first diffraction grating is arranged on a first object located to oppose a second object, a reflecting surface is arranged at a position of the second object which corresponds to the first diffraction grating, and the method includes the step of irradiating the firstdiffraction grating with a radiation beam of coherent light or quasi-monochromatic light and measuring/setting the gap between the first and second objects in accordance with a change in intensity of one diffracted light components from the first diffraction grating.