Granted Patent
Utility
US 4,691,990 · App. 06/670,280
Optical fiber with depressed index outer cladding
Inventors:
Leonard G. Cohen, David W. Johnson, Jr., John B. MacChesney
Patented Case
View Patent ↗
Granted: Sep 8, 1987
Filed: Nov 13, 1984
Inventors
Leonard G. Cohen
David W. Johnson, Jr.
John B. MacChesney
Assignee (at issue)
American Telephone and Telegraph Company, AT&T Bell Laboratories
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.