3-DIMENSIONAL MEASUREMENT OF HEAD FLYING HEIGHT AND ATTITUDE USING IMAGE-PROCESSING OF FRINGE PATTERNS FORMED BY MICHELSON LASER INTERFEROMETRY

In-situ measurement of head flying height and attitude using image pro cessing of fringe patterns formed by Michelson interferometry is studi ed. A wide laser beam is applied to illuminated the slider back surfac e and disk surface simultaneously to create interferometric fringe pat terns. Employing the relationship arising between the two fringe patte rns, the calculation procedure is formulated to yield the slider's par allel, pitch and roll displacements. Experimental fringe patterns are captured in a single visual field by a high-speed CCD camera. Image pr ocessing for a higher signal-to-noise ratio, such as smoothing, filter ing, amplification and ridge line extraction is then applied to the im age data. Additionally, average processing with respect to multiple fr inge lines to produce higher accuracy is successfully applied. Measure d values of flying height and pitch and roll displacements are confirm ed to be in good accordance with the calculation results, demonstratin g excellent applicability of the present method down to the near-conta ct region.