Extracting media noise characteristics from MFM images

Magnetic force microscopy (MFM) is used to study the noise characteristics of magnetic media. In DC or AC erased areas of the media the noise is characterized by two parameters: the standard deviation of the signal and the average correlation length along and perpendicular to the DC erase direction. In regions of the media where signals are written, the noise is characterized by three parameters which describe the distortions of the signal: the standard deviations of the amplitude, the pulse-width at half-amplitude, and the jitter in the pulse position. The resolution of the MFM is exploited to study the dependence of the noise on sub-micron read widths.