title: P(VDF-TrFE) transducer with a concave annular structure for the measurement of layer thickness.
abstract: A new type of transducer that measures the layer thickness at a small spot by spectroscopy is developed. It is made of piezoelectric copolymer film P(VDF-TrFE) with a concave annular structure. This transducer converges an ultrasonic wave on the specimen surface with oblique incidence. The layer thickness is estimated by means of a dip in the frequency spectrum of a reflected wave. Theoretical analysis using the angular spectrum theory and experimental evaluation of the transducer are described. The transducers operate in a frequency range from 7 MHz to 90 MHz. The output variation when the transducer scans a thin wire is in good agreement with a calculation of a line spread function. The lateral and axial resolutions estimated by the calculation of a point spread function are 0.61 lambda and 8.05 lambda, respectively.
authors.affiliation: Toppan Printing Co. Ltd., Saitama.
authors.forename: M
authors.initials: M
authors.lastname: Saito
authors.forename: Y
authors.initials: Y
authors.lastname: Tsukahara
authors.forename: K
authors.initials: K
authors.lastname: Koyama