Method and apparatus for measuring the surface temperature of a disk

A technique for determining the recording medium temperature, thereby enabling high track density in Hybrid recording. This allows compensation for changes in the ambient temperature and variations in the laser power over its life. Such a temperature measuring technique also enables laser power shaping of the spot size/thermal contour in the medium, providing smaller spot size definition with a given optical system. Baseline modulation is a sensitive probe of the temperature gradient between a magneto-resistive read element (anisotropic or giant) and the surface of a disk. By calibrating the temperature rise (above ambient) of the read element, this technique can be used to determine the disk surface temperature.