A high dynamic range method for the direct readout of a dynamic phase change in homodyne interferometers

Author(s)

Marcal, L. A. P. ^[1] ; Kitano, C. ^[1] ; Higuti, R. T. ^[1] ; Nader, G. ^[2] ; Silva, E. C. N. ^[3]

Affiliation

^[1] UNESP Univ Estadual Paulista, Fac Engn Ilha Solteira, Dept Elect Engn, BR-15385000 Ilha Solteira, SP - Brazil

^[2] Ctr Metrol Fluidos, IPT, BR-05508901 Sao Paulo - Brazil

^[3] Univ Sao Paulo EPUSP, Escola Politecn, Dept Mechatron & Mech Syst Engn, BR-05508900 Sao Paulo - Brazil

• Document type: Journal article
• Source: MEASUREMENT SCIENCE & TECHNOLOGY; v. 23, n. 12 DEC 2012.
• Web of Science Citations: 0

Abstract

Piezoelectric flextensional actuators (PFAs) are an efficient alternative to systems that demand nano-positioning of devices, such as in nanotechnology. Optical techniques constitute an excellent choice for contactless measurement of nano-displacements. In particular, optical interferometry constitutes an adequate choice for characterizing PFAs. There are several types of interferometers, as well as optical phase demodulation methods, used in practice. One interesting class of demodulation methods uses the spectrum of the photo-detected signal and its intrinsic properties when there is a harmonically varying time-domain modulating signal. In this work, a low cost homodyne Michelson interferometer, associated with simple electronic circuits for signal conditioning and acquisition, is used. A novel dynamic phase demodulation method, named J(m)\&J(m+2), is proposed, which uses only the magnitude spectrum of the photo-detected signal, without the need to know its phase spectrum. The method is passive, direct, self-consistent, without problems of phase ambiguity and immune to fading, and presents a dynamic range from 0.45 to 100 rad displacements (between 22.6 nm and 5 mu m, for lambda = 632.8 nm). When applied to the measurement of half-wave voltage in a proof-of-concept Pockels cell, it presents errors smaller than 0.9% when compared to theory. For the estimation of PFA displacement, it allows the measurement of linearity and frequency response curves, with excellent results. (AU)

• FAPESP's process: 12/01629-7 - Characterization of novel classes of piezoelectric flextensional actuators and multi-actuated piezoelectric actuators by using optical interferometry
• Grantee: Claudio Kitano
• Support Opportunities: Regular Research Grants