Frequency response of a magnetooptic sensor using magnetic pulses

Abstract

The great advantage of using thin cobalt films as magnetooptic material in sensors to measure currents or magnetic fields is its wide bandwidth because it can reach the magnitude of several GHz. Though this fact is widely known, no effective measures have been taken. The aim of this paper, is to measure the frequency response and the bandwidth of a magnetooptic sensor based on thin cobalt films. Two experiments have been mounted regarding the range of frequencies in study. In the first stage, almost 200 Hz were reached using a sinusoidal magnetic field created with a Helmholtz coil. This frequency is suitable to measuring power lines currents or mag-netic fields. Due to the fact that this coil has an extremely high impedance at high frequencies, an alternative method based on magnetic impulses has been developed. The range of frequencies is improved considerabily up to MHz.