| 摘要 |
The device comprises at least one radiation source (5, 5') and at least one radiation-sensitive detection system (9, 9') comprising at least two detectors (10, 11; 10', 11'), the output signals of the detectors providing an indication about the direction of the radiation from the radiation source which is diffracted in a first radial order b(-1) by the information structure (3,4), and hence about the position of the centre (M) of the track structure (4). This device enables optical record carriers (1) without centre hole to be put to practical use. |
