Procedure for Calibration of Ferrite Gaps in Magnetic Tape Heads Traceable to NBS (National Bureau of Standards) AR-Chromium Optical Linewidth SRMs

摘要

Accurate calibration of micrometer and submicrometer optical line-width measuring systems requires that the calibration standard match the properties of the line to be measured. The NBS photomask linewidth standards have been designed for use by the integrated circuit community and are not directly suitable for use in other applications. A method of calibrating systems for measuring the width of ferrite gaps in magnetic tape heads has been developed that involves a two-step calibration using the NBS antireflecting-chromium photomask as the primary reference standard. This primary standard is used in transmitted green light to calibrate the linewidths on a secondary black-chromium photomask.