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. 08, 1978
Filed:
Jul. 06, 1977
Nobuyoshi Tanaka, Yokohama, JP;
Naoki Ayata, Yokohama, JP;
Mitsuo Takeda, Kawasaki, JP;
Susumu Matsumura, Kawasaki, JP;
Kazuya Matsumoto, Yokohama, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
Film of a known refractive index whose thickness is to be measured is illuminated by a white light beam. Two wave fronts from both sides of the film are directed to an interferometer. The wave fronts are out of phase in accordance with the thickness of the film. The two wave fronts are amplitude-split, respectively, by the beam splitter of the interferometer. Two of the split wave fronts are tilted by tilting means in the interferometer. The other two split wave fronts, as well as the two tilted wave fronts, are directed to an interference surface. Thus, there is formed a white interference pattern on the interference surface. The white interference pattern has a middle peak and two side peaks. The space interval between these peaks is measured by a scanner. By knowing the peak-to-peak interval, it is possible to discriminate the space interval between both sides of the film.