Non-repeatable flutter of magnetic recording disks

The non-repeatable disk flutter in a magnetic recording disk drive is investigated using laser Doppler interferometry. The transverse non-repeatable motion at the outside and the inside of a 350 mm (14") disk is measured, and the amplitude distribution of the true disk deformation is obtained. Results are then presented for a helium environment, in which flutter is substantially reduced. In addition, the peak statistics of the flutter are studied, and it is shown that they follow a Rayleigh distribution instead of a Gaussian distribution. Finally, the frequency content of the flutter is presented.