| 摘要 |
A scanning unit (2, 7) for a magnetic disk with a storage medium (1) disposed optically in the radial direction comprises, in addition to a magnetic write/read head (2, 7'), an optical sensor (2) which detects the actual position for dynamic track following. The optical sensor (2) is designed as a beam waveguide arrangement with a DFB (distributed feedback) laser (21) as the radiation source. A beam splitter (22) splits the emitted laser beam into two equivalent partial beams which scan the storage disk at a distance (D) apart which is a multiple of the track spacing. A detector element (27) is arranged in the path of each of the two partial beams reflected by the storage disk. The difference signal derived from their output signals is an index of the track position. The optical sensor (2) and a thin-film magnetic head (7') are preferably arranged on a common substrate (28). |
