title: Nanometer displacement measurement using Fresnel diffraction.
abstract: We introduce a relatively simple and efficient optical technique to measure nanoscale displacement based on visibility variations of the Fresnel diffraction fringes from a two-dimensional phase step. In this paper we use our technique to measure electromechanical expansions by a thin piezoelectric ceramic and also thermal changes in the diameter of a tungsten wire. Early results provide convincing evidence that sensitivity up to a few nanometers can be achieved, and our technique has the potential to be used as a nanodisplacement probe.
authors.affiliation: Optics Research Lab 3, Department of Physics, University of Tehran, Tehran, Iran.
authors.forename: Ali Akbar
authors.initials: AA
authors.lastname: Khorshad
authors.forename: Khosrow
authors.initials: K
authors.lastname: Hassani
authors.forename: Mohammad Taghi
authors.initials: MT
authors.lastname: Tavassoly