Search results

The areal (surface area density of bits) storage density of magnetic hard disks is continually increasing, with typical available commercial storage densities being around 10Gbits/in². It is predicted that densities in excess of 40Gbits/in² will be possible before the year 2003. A number of key issues arise from this development, such as the need to determine and control accurately the dynamic flying height (z‐axis) of the read‐write head, which is affected by the apparent distortion of the disk surface due to rotation‐induced disk resonance. As a result of the increasing storage density the positional control of the head in the plane of the disk (x‐y plane) also becomes more critical. This paper deals generally, but with a particular emphasis on optical and piezoelectric sensors used in our laboratory for characterisation of storage media and systems.