No abstract

No abstract

We propose a new transduction mechanism for fiber optic pressure sensing: pressure-induced microbending, which produces excess optical attenuation in the fiber. A simple bending transducer has been used to determine the response of a step-index multimode fiber to changes in applied pressure. The potential (low frequency) acoustic sensitivity of such a transducer, calculated from this measured response, is approximately 100 μPa into a 1-Hz detection bandwidth.

The effect of conductivity on the spin-wave spectrum of thin Permalloy ferromagnetic films has been investigated. If conductivity effects are included and a simple surface anisotropy is assumed, it is known that the calculated mode locations and amplitudes for Permalloy films are in excellent agreement with some experimental data in the range 800–2700 Å in thickness. If conductivity effects are omitted, a much simpler calculation is possible, but the error in mode location and amplitude has been unknown. For both perpendicular and parallel resonance geometries, detailed calculations reported here have shown that mode locations are not significantly affected over the above thickness range, and that the main mode amplitude is in error by only 20% at 800 Å thickness. However, for 2000 Å thickness, the main mode amplitude is in error by a factor of 2.5.

No abstract