Granted Patent
Utility
US 4,885,231 · App. 07/191,186
Phase-shifted gratings by selective image reversal of photoresist
Inventor:
Winston K. Chan
Patented Case
View Patent ↗
Granted: Dec 5, 1989
Filed: May 6, 1988
Inventor
Winston K. Chan
Assignee (at issue)
Bell Communications Research, Inc.
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.