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:
Aug. 29, 1995
Filed:
Oct. 30, 1992
Burn J Lin, Austin, TX (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A phase-contrast microscope with a quarter-wave plate in a pupil plane with a thickness of .lambda..theta./2.pi. is provided for the inspection of a phase-shifting mask. The angle .theta. and the wavelength .lambda. are adjustable to optimize the phase detection sensitivity. A similar .theta. and .lambda. optimization scheme is applied to an interference microscope assembly wherein an inspection beam is split into two beams by a beam splitter to be reflected by mirrors and then recombined at a second beam splitter. A mirror in one of the beams can be moved to change .theta. to its optimum value at a given .lambda. which can be changed by light source selection or by filter change.