Stylus type instruments that employ needle tracers for examination of surfaces by means of translating the stylus over the surface and recording the undulations which occur during that traverse are analyzed by means of scanning electron microscopy. The scanning electron microscope (SEM) has superior resolution capabilities and can directly record the interactions of stylus with surface. The true levels of resolution of this instrument are measured and discussed in terms of finite size of the stylus, damage produced in the specimens due to stylus plowing, and stylus skipping and nonparallel tracking. The fundamental difference between magnification and resolution is examined in terms of tracer devices. Needle or stylus tracer devices are found to be dynamic microhardness testors which produce outputs which must be carefully judged as to their meaning and reliability in terms of faithfully recording the topographical nature of surfaces. The potential future of the SEM as a true nondestructive surface quality inspection tool is emphasized.

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