Title :
P(VDF-TrFE) transducer with a concave annular structure for the measurement of layer thickness
Author :
Saito, Masao ; Tsukahara, Yusuke ; Koyama, Kiyohito
Author_Institution :
Toppan Printing Co. Ltd., Saitama, Japan
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.<>
Keywords :
acoustic imaging; piezoelectric transducers; polymer blends; thickness measurement; ultrasonic measurement; ultrasonic transducers; 7 to 90 MHz; P(VDF-TrFE); PTrFE vinylidene fluoride trifluoroethylene copolymers; PVDF; angular spectrum theory; axial resolutions; concave annular structure; experimental evaluation; frequency range; frequency spectrum dip; lateral resolution; layer thickness measurement; line spread function; oblique incidence; piezoelectric copolymer film; point spread function; reflected wave; small spot; spectroscopy; thin wire; ultrasonic transducers; Frequency estimation; Optical films; Piezoelectric films; Piezoelectric transducers; Spectroscopy; Surface waves; Thickness measurement; Ultrasonic transducers; Ultrasonic variables measurement; Wire;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
