USE OF SPECULAR OPTICAL SYSTEM TO MEASURE HDD SLIDER FLYING HEIGHT TO A HIGH LEVEL OF ACCURACY

Abstract

Finding a method of accurately measuring ultra-low flying heights (FH) of an HDD slider is becoming more and more important. We have developed a way of using a specular optical system to measure the FH to a high level of accuracy. While the basic method is to measure the height of a slider flying over a bare glass disk, this method can also be used to measure one flying over a glass disk with a overcoat (OC) and a lubricant agent (Lube) and thus to observe the touch down (TD) or the take off (TO) behavior. We theoretically investigated the effect of the OC and the Lube layer on the accuracy of the measurement and a method to compensate for their effect. With this compensation, we could measure the FH using a glass disk with OC and Lube.