Effective Refractive Index Method for A Flying Ileight Sensor using Frustrated Total Reflection and Its Application to Flying Height Measurement on An Actual Magnetic Disk

It is necessary to measure the flying height of a slider on an actual magnetic disk when designing magnetic disk drives. However in typidcal spacing measurement methods, the magnetic disk is usually replaced with a glass disk. In order to measure this real spacing, we developed a flying height sensor based on Frustrated Total Reflection. To measure the real flying height optically, the phase shift on reflection at magnetic disk is an important problem. In this paper we describe theoretical treatment of the problem and introduce the modified effective refractive index method and measure the effective refractive index of an actual magnetic disk. Flying height on the magnetic disk was also measured using the obtained effective refractive index. The result was compared with the flying height measurements measured by the traditional interference method. They agreed with each other with an error less than 2 nm.