100-nm-Wide track pattern readout using a protruded triangular aperture mounted optical head slider

In this study, we evaluated the read-out signal quality from narrow track patterns, utilizing linearly arranged slender track patterns, while changing the track width from 10 to 0.1 μm and the pattern density from 200 nm line-and-space (L/S) to 120 nm L/S. To acquire narrow track readout signals, we adjusted the aperture’s in-plane position to cross a linear track at shallow angles of less than 1°, and we could successfully transform directly acquired signals into those of an aperture crossing tracks at a right angles. The results of an experiment utilizing a 10-μm-wide track (which is thought to represent an infinitely wide track) clarified that the stationary field was spread to an approximately 1.2–1.6 times larger region than the typical aperture size of 330 nm. The results also clarified that the “field spread” depended on the pattern density, that is, the case in which polarization direction θ equals 0 or 45°, and that the field spread increased monotonically as the line or space width became smaller. When the polarization direction equals 90°, the field spread had its local maximum when the line or space width was approximately 150 nm. An approximate prediction of the read-out signal amplitude was based on the rule that the signal amplitude was proportional to the net field spread that passed across the track pattern, and this prediction corresponded well to the experimental results, except when the interaction between the stationary field and the track side walls was not taken into account.