Abstract: A magnetic head slider consisting of a mixed ceramic made of aluminum oxide/titanium carbide has on its sliding side adjacent a magnetic record carrier a thin layer from which the titanium carbide component has been removed. The titanium carbide component preferably is removed by preferential reactive ion etching in a CF.sub.4 plasma. The magnetic head slider with its sliding surface thus modified exhibits greatly improved sliding properties compared with sliders of the same material having a non-modified sliding surface.

Abstract: A straight line whose azimuth angle is to be measured, such as the angle of a gap of a magnetic head assembly relative to a disk radius, is imaged on an evaluation plane via a lens and a pair of deflecting mirrors, the first of which is semi-transparent. The mirrors are each inclined at a different angle from a common pivot line. The angular difference is such that the images do not touch and only one end portion of each image from the mirrors lies in the image field. The lateral spacing of these end portions is a function of the azimuth angle. A mask blocking out the center portion of the image may be used to assist in the end portion definition.