Method for determining characteristics of an asperity based upon detection members having a unique vibration frequency

A method for determining characteristics of an asperity on a surface of a disc comprising the steps of:

• providing a head including a body having a leading edge, a trailing edge, and an air bearing surface, said air bearing surface including a plurality of spaced detection members, each of the plurality of detection members having a unique vibration frequency upon excitation to distinguish each of the plurality of detection members excited by contact with an object, each of the plurality of detection members being coupled to a detection device to detect vibration of each of the plurality of detection members;
• flying the head above the surface of the disc at a pitch angle θP and a height Hfly as the disc is rotated;
• detecting excitation of each of the plurality of detection members excited by contact with an asperity based upon the unique vibration frequency of each of the plurality of detection members;
• calculating a height of the asperity based upon a height of excited detection members above the disc surface.