title: Measurement of in-plane displacement by wavelength-modulated heterodyne speckle interferometry.
abstract: The use of wavelength-modulated light incorporated into an optical-path-difference speckle interferometer is demonstrated as a heterodyne technique for measuring the in-plane displacement of a rough object. The in-plane displacement can be determined from the measured phase variation of the heterodyne speckle signal. We also improved the optical configuration to create a high-contrast interference pattern. Experimental results reveal that the proposed method can detect displacement up to a long range of 220 μm and displacement variation down to the nanometer range. Moreover, the sensitivity can reach up to 0.8°/nm. The performance of the system is discussed.
authors.affiliation: Department of Mechanical Engineering, National Central University, Chung-Li 32054, Taiwan. juyilee@ncu.edu.tw
authors.forename: Ju-Yi
authors.initials: JY
authors.lastname: Lee
authors.forename: Ming-Pei
authors.initials: MP
authors.lastname: Lu
authors.forename: Kun-Yi
authors.initials: KY
authors.lastname: Lin
authors.forename: Szu-Han
authors.initials: SH
authors.lastname: Huang