Spin-Stand Based Measurement of 1-D Head Response Function

Recently, an efficient spin-stand based imaging technique for viewing magnetization patterns written on hard disk platters has been developed. This technique requires the intersymbol interference (ISI) removal from raw read-back images. This removal can be accomplished by using the response function characterization of giant magnetoresistive heads. The precise measurement of the head response function can be of great importance in magnetic recording as well. This paper presents a new approach to head response function measurement. The central idea of this measurement is based on the fact that the readback signal is a convolution of the head response function and the virtual magnetic charge distribution corresponding to magnetization patterns recorded on the media. For this reason, it is apparent that for a single isolated transition the readback signal will emulate the response function when the width of the isolated transition becomes much narrower than the width of the response function itself and the corresponding charge distribution can be modelled by the Dirac delta-function. This implies that as the isolated transition is progressively narrowed, the readback signal should converge to the actual head response function. This has been confirmed by numerical simulations as well as by experimental studies that are presented below.