| 摘要 |
PURPOSE:To transmit the energies of the light beams of a semiconductor laser efficiently and reduce the focus to a minute spot by using the semiconductor laser for an information recording light source and a gas laser for a focus controlling auxiliary light source. CONSTITUTION:Recording signal modulates the light beam L1 of a semiconductor laser 1 by way of a driving circuit 2. And the modulated light is recorded on a recording medium 9 by way of concave and convex cylindrical lenses 4, 5, tracking mirror 6, iris lens 7. On the other hand, the light beam L2 of a gas laser 11 is projected to the medium 9 via projecting lens 12, beam splitter 13, tracking mirror 14, lens 7 and the reflected light thereof is changed of its optical path by the mirror 14 and is received in an element 15 via the splitter 13. The supporting device 8 of the lens 7 is then controlled by the output of a differential amplifier 16, whereby the distance between the lens 7 and disc 9 is maintained constant. At the reproducing of th information, the light beam L1 is set at a weak constant output, and the transmitted light of the medium 9 is received 17 and outputted. |
