Patent ID: 8416650
Filing Date: 2013-04-09
Classification: G11B

Abstract:
1. A method for detecting a protrusion height of a second protrusion from a first protrusion of a magnetic head slider including a near-field light generator that, by laser light being supplied, is thermally-expanded and that generates near-field light on an air bearing surface, wherein an incorporated heater is activated to thermally-expand the magnetic head slider so that the first protrusion is generated on the air bearing surface and the second protrusion protruding from the first protrusion is generated by the thermal expansion of the near-field light generator, the method comprising: a step for preparing a recording medium to which a standard signal is written with a predetermined magnetization; a step for obtaining a relation, as a first relation, between a first spacing, which is a spacing between the first protrusion and the recording medium, and power of the heater; a step for obtaining a relation, as a second relation, between a residual magnetization of the standard signal and the power of the heater in a state where the first and second protrusions are generated by lowering the magnetization of the standard signal by heating the recording medium with the near-field light while light output of laser light is maintained to be constant and the power of the heater is varied; a step for obtaining a relation, as a third relation, between the first spacing and the residual magnetization from the first and second relations; and a step for obtaining a value of the first spacing as the protrusion height of the second protrusion from the first protrusion when the second protrusion contacts the recording medium from the third relation, the value of the first spacing being determined where an absolute value of a change rate of the residual magnetization with respect to the first spacing is less than a predetermined standard value.