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. 14, 1990
Filed:
Oct. 13, 1988
Akira Ishida, Tsukuba, JP;
Research Development Corporation of Japan, Tokyo, JP;
Abstract
An apparatus for measuring displacement by light wave interference, wherein means are provided to determine true displacement in spite of atmospheric flicker in the light path. Two coherent light beams of different wavelengths are transmitted over a common path and reflected from a light reflector means, the displacement of which is to be measured. The reflected beams are separated and compared with reference beams to measure a phase difference for each reflected beam, and signal processing means is provided for calculating atmospheric flicker error from the phase differences, and for determining true displacement by taking the measured error into consideration.