Abstract: A lapping guide is provided to determine the position at which lapping of a thin film head to define pole faces should be terminated. Accurate positioning of the lapping guide with respect to the head is insured by forming various elements of the lapping guide during the same photolithographic process steps as those used to form elements of the head. The lapping guide may be used either as an electrical or optical guide. When used as an optical guide, a second lapping guide may be provided as an indicator that more frequency inspection is necessary.

Abstract: A differential Hall effect magnetic read head exhibiting improved resolution. The head includes dual Hall elements in which the elements are oriented so that their major surface is perpendicular to the surface of the recording medium and biased so that they respond to the component of magnetic flux which is parallel to the surface of the recording medium. Operation in this manner enables information recorded at extremely high densities to be easily read. In an alternative embodiment, a single Hall element is utilized and direct and delayed outputs are differentially compared in order to detect flux transitions.