Apparatus for measuring curvature of magnetic read/write head sliders

Abstract

An apparatus for measuring a curvature of an air bearing surface (ABS) of a read/write magnetic head slider. The apparatus has two lasers which direct laser beams toward the ABS. The beams strike the ABS and are specularly reflected. The reflected beams are directed toward a position sensing optical detector. The distance between the points where the beams strike the detector is indicative of the curvature of the ABS. The beams my be alternately pulsed so that the detector outputs a DC-biased square wave signal, the voltage-step difference of which indicates the curvature. In another embodiment, a single laser beam is scanned by a scanner and passed through a scan lens. The scan lens is located one focal length from the scanner. A reflected laser beam is reflected from the ABS and is collected by the scan lens. The reflected laser beam is then directed toward a position sensing optical detector. The detector is located outside the focal plane of the scan lens. The position of the laser beam on the detector is dependent upon the curvature of the ABS. Then the magnitude of the detector output provides a measure of the curvature.