Patent ID: 7221460
Filing Date: 2007-05-22
Classification: G03B,G03F

Abstract:
1. An optical system having a plurality of optical elements, comprising: a reference mirror; a first measuring system for measuring a relative position, with respect to said reference mirror, of a first optical element among the plurality of optical elements and/or a first target mirror disposed so that a relative position thereof with respect to the first optical element is kept substantially unchanged; a second measuring system for measuring a relative position, with respect to said reference mirror, of a second optical element among the plurality of optical elements and/or a second target mirror disposed so that a relative position thereof with respect to the second optical element is kept substantially unchanged; and a driving mechanism for moving at least one of the first and second optical elements on the basis of a result of measurement made by said first and second measuring systems, so that a relative positional relationship between the first and second optical elements is placed in a predetermined positional relationship.