Absolute head media spacing measurement in-situ

As the flying height (FH) goes to sub-10 nm, the actual FH and the flying stability of slider become even important to maintain the reliability of head-disk interface. Currently, the FH testing uses white light interferometry method. Due to ESD and the cost etc. issues, the FH of slider is only sample tested at a small percentage. The read/write based in-situ FH testing methods do not have these concerns. But the absolute FH cannot be got unless doing the touch down test. However, the head cannot afford the touch down for current GMR head. This work proposes a new method to test absolute head media spacing in-situ without physically changing the FH.