Simultaneous measurement of head-disk spacing and reproduced output in flexible perpendicular magnetic recording disk drive

In practical application of perpendicular magnetic recording, the recording density is mainly limited by spacing loss. Therefore, a proper measuring method for the spacing loss is required. A new system capable of dynamic measurement of spacing distribution between head and flexible disk have been developed by using the optical interference technique. The performance of this system is as follows. (a) Measuring precision of spacing : ±20 nm (b) Sampling frequency : 3.2 kHz (c) Resolution on scanning line : 6.5 μm By using this system and an auxiliary pole driven single-pole type head, spacing changes and amplitude variations of reproduced output are simultaneously measured as continuous data. Furthermore it is shown that the spacing loss can be obtained by this method and is -(190±7)d/λ dB at 53.7 kFRPI as an example where d and λ are spacing and recorded wavelength respectively.