Method for testing performance of a magnetic head slider

A method for testing performance of a magnetic head slider used in a disk drive unit having a rotatable disk, a read head incorporated in the slider for reading data from the disk, and a fly-height actuator for changing spacing between the disk and the slider, the method comprising the steps of:

• (1) rotating the disk and positioning the slider over the rotating disk at an initial fly-height;
• (2) exciting the fly-height actuator to make the slider touch the disk and recording a touch down spacing of the read head of the slider;
• (3) backing off the slider at a predetermined backoff amount from the disk;
• (4) testing dynamic performance of the slider to obtain a reference value which is related to the spacing between the disk and the slider;
• (5) varying the initial fly-height of the slider;
• (6) repeating the steps (2) to (4) with the backoff amount fixed;
• and
• (7) calculating a dynamic fly-height gamma ratio based at least in part on the recorded touch down spacing and the obtained reference values.