Abstract:
A system for finding a transducer resonant frequency, comprising: an initialization unit (11), a phase determination unit (12), an interval hopping control unit (13), a hopping interval generation unit (15), a frequency output control unit (17), a phase collection unit (16), and a resonant frequency point acquisition unit (14). Each hop allows a search range to be reduced by at least half of that of the previous interval, thus allowing for reduced amount of searches.
Abstract:
A focusing electromagnetic acoustic transducer is provided which comprises a pair of meander coils, three insulation sheets and a magnet. The meander coils are formed on both surfaces of one of the insulation sheets to be positioned such that the meander coils are coincident with each other, and they are covered with the other insulation sheets. Each of the meander coils comprises a plurality of coil segments wherein intervals between adjacent coil segments sequentially are varied from one end to the other end. The magnet is positioned above the layers consisting the meander coils and insulation sheets. The coil segments of each meander coil are straight lines in parallel with each others, sector shapes on respective circulars having the same center point, or generally circular shapes having the same center point