Effect of the in-plane field component on the response of the magneto optical indicator film sensors

In this work we present a study of the effect of the in-plane component of magnetic stray field on the response of Magneto Optical Indicator Film (MOIF) sensors. To take into account this effect, which was neglected in all MOIF measurements done so far, a small bias field with in-plane orientation is applied and the MOIF response thus obtained is compared with the results of numerical modelling. Thus the complete vectorial value of stray field can be determined. Moreover, we show that in a wide range of magnetic fields, up to approximately half the saturation field, the effect of the in-plane field component can be neglected and thus MOIFs are sensitive only to the normal field component, thus making it possible to measure this component directly.