| 摘要 |
PROBLEM TO BE SOLVED: To provide an improved displacement measuring system to be used in a lithography projector. SOLUTION: This displacement measuring system for measuring the position of an optical element in the projection system of a lithography projector utilizes a first grating mounted on the optical element and an interference measuring principle accompanied with the use of a second grating mounted on a reference frame. COPYRIGHT: (C)2004,JPO |
