Method and apparatus for reading a clock track with a magneto-optical clock head using the transverse Kerr effect

摘要

A magneto-optical clock head is disclosed. The magneto-optical clock head allows a longitudinally recorded clock track to be read from a disk surface from a position outside of a head-disk assembly (HDA). The clock track has sections of alternating magnetization which define transitions. Importantly, the magneto-optical clock head is used to sense the transitions using the transverse Kerr effect, as opposed to the longitudinal Kerr effect as used in one prior technique. In one embodiment, the magneto-optical clock head includes a light source for generating a p-polarized beam which is aligned in such a manner that it strikes the clock track. A reflected beam is then produced which has an intensity that varies based upon the direction of the magnetization of the sections of alternating magnetization of the clock track due to the transverse Kerr effect. A detector is provided to detect the intensity variations in the reflected beam and to ultimately generate a clock signal which is provided to transducers to allow them to appropriately write servo information onto their respective disk surfaces. A method for optically reading a clock signal stored within a clock track which is written onto a disk surface that is located within a head disk assembly of a disk drive is also provided.