The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 24, 1992
Filed:
Apr. 28, 1992
Akiyoshi Suzuki, Tokyo, JP;
Tetsuya Mori, Yokohama, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
An alignment system for aligning a first object, having a first alignment mark, and a second object having a second alignment mark, disposed at a position which is approximately conjugate with the first object with respect to a projection optical system. The alignment system includes a detecting device for detecting light from the first and second alignment marks with light irradiated by light. The detecting device detects the light from the second alignment mark as passed through the projection optical system and the first objects. An adjusting device adjusts the spacing between the first object and the second object in the direction of an optical axis of the projection optical system. The adjusting device is arranged to change the optical path length for the light from the second alignment mark, between the first and second objects, by the adjustment of that spacing, control device controls the adjusting device. The detecting device can produce a first signal based on the light from the first and second alignment marks at a first distance, and a second signal based on the light from the first and second alignment marks at a second distance. The control device is operable to determine a positional deviation between the first and second objects on the basis of the first and second signals, and the relative position of the first and second objects can be adjusted to correct the positional deviation.