| 摘要 |
In an optical scanning device for recording and reading both a high-density, HD, record carrier (30) and a low-density, LD, record carrier (36), a two-wavelength diode laser (1) is used for generating the HD scanning beam (4) and the LD scanning beam (6). In the path of both the HD beam and the LD beam two diffraction structures (52; 54) are arranged, one of which forms a three-spot grating for only one of the beams and the other forms a three-spot grating for only the other beam. The diffraction structures are preferably integrated in one element. |
