title: Zero reference signal for displacement measuring systems by use of speckle.
abstract: An optical method for generating a reference signal for an incremental displacement measurement system is proposed. We achieved this zero reference signal by comparing two speckle patterns arriving from two symmetric diffusers, which are used as natural random codes that are identical only when the reading head is located equidistantly between the diffusers. The comparison of the speckles is obtained either by interference, as in a Michelson interferometer, or by intensity correlations.
authors.affiliation: Departamento de Física, Facultad de Ingeniería, Universidad de Buenos Aires, Paseo Colón 850, (1063) Buenos Aires, Argentina. fperez@fi.uba.ar
authors.forename: Fernando
authors.initials: F
authors.lastname: Pérez-Quintián
authors.forename: José
authors.initials: J
authors.lastname: Alonso
authors.forename: Jesús
authors.initials: J
authors.lastname: Atencia
authors.forename: Eusebio
authors.initials: E
authors.lastname: Bernabeu