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. 01, 1994
Filed:
Nov. 24, 1992
Michael W Farn, Burlington, MA (US);
Massachussetts Institute of Technology, Cambridge, MA (US);
Abstract
A technique for aligning corresponding features on opposite surfaces of a transparent substrate. In one embodiment thereof a laser beam is applied to a pair of grating elements on one surface of the substrate to produce an interference fringe pattern on the opposite surface, the centerline between the grating elements being at a known distance from the features on the one surface and corresponding to the center bright space of the fringe pattern. A reference mark on a movable mask, which reference mark is at the same known distance from feature locations on the mask, is aligned with the center bright space of the interference fringe pattern and the feature locations on the mask can then be used to position features on the opposite surface which are aligned with the features on the one surface of the substrate.