| 摘要 |
PURPOSE:To attain single track recording and multi-track reproducing and to reproduce data at a high speed by synthesizing an light bean from one laser beam generator with one of the plural light beams from another laser beam generator. CONSTITUTION:A light beam outputted from a first laser diode 2 is branched into plural beams by a diffraction grating 3. A light beam outputted from a second laser diode 5 is synthesized with one of said plural light beams by a prism 6. Thus synthesized one light beam and the remaining beams are supplied to an optical disk 1 via a beam splitter 7. The reflecting light beams coming through the splitter 7 are detected by a photodetector 12, and one of the detection signals from it 12 is selected by switches 14a-14c and inputted to a focus control circuit 18. Thus an objective lens 10 is driven and the purpose is accomplished. |
