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:
Sep. 19, 2000
Filed:
Jun. 24, 1998
Applicant:
Inventors:
Jan E Van Der Werf, Eindhoven, NL;
Philippe J Belien, Hasselt, BE;
Johannes C Rijpers, Eindhoven, NL;
Assignee:
ASM Lithography B.V., La Veldhoven, NL;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G01B / ;
U.S. Cl.
CPC ...
356349 ; 356358 ;
Abstract
In an interferometer system, variations of the refractive index in the medium traversed by the measuring beam (123) can be detected by using two measuring beams (123, 125) having wavelengths which differ by a factor of three. For this choice of the wavelength ratio, the interference filters of the polarization elements, such as the beam splitter (127), the .lambda./4 plates (130, 131) and the antireflection coatings can be manufactured relatively easily, and the detection accuracy is increased.