title: Simultaneous observation of acoustic resonance phenomena at both surfaces of a plate coated with thin layers.
abstract: Acoustic resonance phenomena at the front and back surfaces of a plate coated with thin layers were successfully observed in the amplitude spectrum of the back surface echo. The amplitude ratio of spectra with and without layers takes its maximum and minimum values at the resonant frequencies of the front and back coatings and both frequencies can clearly be distinguished from each other. As an application, the thicknesses of the front and back coatings on a steel plate were measured simultaneously using their resonant frequencies, thus verifying the validity of the principle.
authors.affiliation: Department of Nanomechanics, Tohoku University, Aoba 6-6-01, Aramaki, Aoba-ku, Sendai 980-8579, Japan. tohmyoh@ism.mech.tohoku.ac.jp
authors.forename: Hironori
authors.initials: H
authors.lastname: Tohmyoh
authors.forename: Tomoya
authors.initials: T
authors.lastname: Sunaga
authors.forename: Manabu
authors.initials: M
authors.lastname: Suzuki