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:
Dec. 11, 2018
Filed:
Jul. 22, 2016
Zhejiang Sci-tech University, Zhejiang, CN;
Liping Yan, Zhejiang, CN;
Benyong Chen, Zhejiang, CN;
ZHEJIANG SCI-TECH UNIVERSITY, Zhejiang, CN;
Abstract
The present invention discloses a dual-homodyne laser interferometric nanometer displacement measuring apparatus and method based on phase modulation. The linearly polarized beam with single wavelength emitted from a single frequency laser is projected onto a dual-homodyne laser interferometer consisting of four beam splitters and two retroreflectors to respectively form a measurement interference signal and a reference interference signal received by two photodetectors, respectively; an electro-optic phase modulator is placed in the optical path and a periodic sawtooth-wave voltage signal is applied to modulate the measurement and reference DC interference signals into AC interference signals; the measured displacement is obtained by detecting the variation of the phase difference between the two interference signals caused by the movement of the measured object. The present invention overcomes the error arising from DC drift in the homodyne laser interferometer and avoids the sinusoidal error caused by the direct subdivision of the interference signal or non-quadrature error of measurement interference signal. The present invention is applicable for the precision displacement measurement with sub-nanometer level accuracy in the fields of high-end equipment manufacturing and processing.