Accurate Measurement of Gas-Lubricated Slider Bearing Separation Using Visible Laser Interferometry

Abstract

This paper outlines an optical method utilizing laser interferometry for measuring the static and dynamic characteristics of self-acting gas-lubricated slider bearings. The method achieves a high accuracy of down to 1–2 nanometers and a wide frequency range of more than 100 kHz by suppressing the adverse effect of undesirable interference patterns through the adoption of optics which permit the laser beam to be focused into a fairly small cavity. Experimental results derived from this method in an ambient helium atmosphere confirm that the modified Reynolds equation can be applied to the prediction of slider flying characteristics within an experimental range of spacing down to 0.025 μm and a corresponding Knudsen number as high as 8. Furthermore, experiments designed to measure slider transient motion as it travels across rectangular grooves or bumps indicate that the measurement system achieves a higher response performance than do conventional systems.