Scanning carrier current method for in-situ measurement of flying height variation

A novel writing process based in-situ flying height measurement method, scanning carrier current method, is proposed. An erasure current oscillating in the frequency range of 200~800 kHz is injected to the write head during the period of interest. Later, its effect on previously written data is detected to infer the flying height during the period of interest. The maximum scanning carrier current method provides a good solution to measure flying height variation in a large range during dynamic transient process. When the slider is in steady flying status, a lower scanning carrier current method can reduce the noise caused by media´s MrT fluctuation, whilst a biased scanning carrier current method is suitable to reduce the noise caused by media´s coercivity fluctuation in the flying height testing process