| 摘要 |
PURPOSE:To perform the read and write of information on two optical disks by one optical head and to lower the cost of the optical head by switching a laser beam by rotating a prism advancing to a pair of convergence lenses arranged symmetrically. CONSTITUTION:A laser beam 10 from a semiconductor laser 15 transmits a beam splitter 21, and is deflected upward by the prism 29 in an objective optical part 26, and transmits a convergence lens 30, and is projected on an optical disk. And reflected light 27 is emitted in a backward direction, and is deflected by the beam splitter 21, and is received at a first photodetecting part as a focusing signal and at a second photodetecting part as a tracking signal, then, the read and the write of the information on the optical disk at an upper side are performed. Next, the prism is rotated by 90 deg., and the laser beam 10 transmits the convergence lens 31, and is projected on the optical disk at a lower side. In such a way, it is possible to perform the read and the write of the two optical disks by one optical head, which lowers the cost of the optical head. |
