Dual beat-frequencies laser Doppler interferometer

A Takita; H Ebara; Y Fujii

doi:10.1063/1.3669785

Dual beat-frequencies laser Doppler interferometer

Rev Sci Instrum. 2011 Dec;82(12):123111. doi: 10.1063/1.3669785.

Authors

A Takita¹, H Ebara, Y Fujii

Affiliation

¹ Department of Electronic Engineering, Faculty of Engineering, Gunma University, 1-5-1 Tenjin-cho, Kiryu 376-8515, Japan.

PMID: 22225203
DOI: 10.1063/1.3669785

Abstract

A dual beat-frequencies laser Doppler interferometer which can measure high speed back and forth motion is proposed and demonstrated. In this interferometer, the two frequencies, f(1) and f(2), emitted by a Zeeman laser are introduced into the signal beams. They are changed to f(1)' and f(2)' by Doppler shift f(Doppler), which is proportional to the velocity of the object. The use of the two beat signals of |f(1)' - f(2)| and |f(1) - f(2)'| appearing at two photodetectors enables to measure the velocity over the limitation v(c) = λ(f(1) - f(2))/2.