Granted Patent
Utility
US 5,436,725 · App. 08/134,729
Cofocal optical system for thickness measurements of patterned wafers
Inventor:
Anthony M. Ledger
Patented Case
View Patent ↗
Granted: Jul 25, 1995
Filed: Oct 12, 1993
Inventor
Anthony M. Ledger
Assignee (at issue)
Hughes Aircraft Company
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.