FLY HEIGHT MEASURING APPARATUS FOR MAGNETIC RECORDER

摘要

PROBLEM TO BE SOLVED: To measure the fly height of a slider accurately without machining the slider additionally by utilizing an insulation film for shielding the slider and a magnetic head as the optical path of a fly height sensor. SOLUTION: A part of an incident light 11 to the reflective surface of a prism coupler 9 is reflected on the boundary between the coupler 9 and a slider 1 to produce a reference light 12 and only some plane of polarization is selected by means of a polarizer 14 and introduced to a photodetector 15 where it is converted into an electric signal E1 . A light incident to an insulation film 3 shielding a magnetic head 2 and the slider 1 impinges on the insulation film 3 at such incident angleθas it is reflected totally on a measuring part 3a. It is delivered from a prism coupler 10 and only a plane of polarization identical to that of the reference light 12 is selected as a measuring light by means of the polarizer 14 and converted into an electric signal E2 by means of the photodetector 15. A fly height operating circuit 17 determines the fly height of the slider 1 based on the electric signal E2 and removes the measurement error based on the ration E2 /E1 of the electric signals E1 , E2 .