MAGNETIC-FIELD MEASUREMENTS USING MAGNETOOPTIC KERR-EFFECT SENSORS

A novel optically based magnetic field sensing technique is developed that uses a thin magnetic film as the sensing element and the longitud inal and transverse magneto-optic Kerr effects in an optical read tech nique. The linear system response is tested for small magnetic fields using a simple free-space ellipsometry measurement system. Measurement s taken at 8 mHz showed a magnetic field sensitivity of 4x10(-3) Oe, w ith a system dynamic range of over 60 dB. The noise spectrum was domin ated by 1/f noise. Calculations for a shot-noise-limited measurement s ystem indicate that a magnetic field sensitivity of 10(-6) Oe/Hz(1/2) may be possible through enhancement of the sensing element parameters and 100-mW light sources.