| 摘要 |
This bubble domain sensor is capable of sensing the presence or absence of a bubble at a predetermined location within bubble supporting material regardless of whether the bubble is stationary or moving through that location. A magnetostrictive material layer, such as a thin film having an area approximately equal to the area of a bubble domain, is positioned with respect to the bubble material such that it is magnetically influenced by the closure field of a bubble at the predetermined location. A conductor, such as a strip conductor, is positioned in contact with the magnetostrictive material. A sonic device launches sonic wave pulses which pass in the vicinity of the magnetostrictive material layer. The sonic wave pulse stresses the magnetostrictive material, and when the magnetostrictive material is magnetically influenced by a bubble, the stress changes or rotates its magnetization thereby inducing an electric signal in the conductor. When a bubble is not near the magnetostrictive material, no signal will be produced. The sonic wave pulse may be launched as either a surface wave on, or a bulk wave in the bubble supporting material, or it may be launched in a material substrate, capable of supporting acoustic waves, which is in contact with the magnetostrictive material. The shape of the magnetostrictive thin film element may have different geometrics, including long strips.
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