Head-medium spacing measurements using a phase comparison between two fringe patterns formed by Michelson laser interferometry through a glass disk

摘要

Head-medium spacing measurements using a phase comparison between two fringe patterns (PCMI: Phase Comparison Michelson Interferometry) was extended to a case using a glass disk in place of actual disks. In the original PCMI, fringe patterns wereformed over a slider back surface and disk surface, which is advantageous in that there was no necessity for a calibration using the First-order Reinforcement Interference (FRI) and is applicable as regards spacing far less than the spacing where the FRIforms, The present extension enables PCMI in the case of flying heads having no reflective space on their back surfaces. Also, the extended PCMI permits direct measurements of absolute spacing values without the needs for any calibration nor anyoperation, which contrasts favorably with the original PCMI wherein relative spacing values can be measured.