Abstract: A read-write head is provided with a plurality of piezoelectric transducers which produce signals related to its movement as it flies over an adjacently rotating recording disk. By filtering these signals to determine their spectral components in low, medium and high ranges, hard contacts between the head and disk, disk wear or roughness and head movement can be determined.

Abstract: A wafer indexing and mapping system is useful for precisely locating artifacts, defects, and fabricated structural components on a wafer. A permanent micrometer grid pattern is applied to the backside of the wafer, for example, a transparent bubble wafer. The grid pattern forms an array of uniform size cells, for example, 40 unit cells wide by 40 unit cells long. Each unit cell is divided into smaller units on each side. Each cell contains a coding or indexing system to identify the row and column of the cell in the grid pattern. The grid pattern contains orientation bars which identify orientation with respect to particular wafer reference lines. The simultaneous viewing of the wafer and the grid pattern permits an accurate permanent mapping of the artifacts, defects, and fabricated structural components on the wafer, as well as on the individual small chips formed by dicing the wafer.