| 摘要 |
PURPOSE:To evade the aberration and the shift of optical axis in a transmission type beam splitter by leading out one diffracted light or a non-diffraction light radiated from an acousto-opto modulator to a monitor photodetector and using one of other radiated light as a main beam CONSTITUTION:A light beam from a laser light source 1 is reflected in moving mirrors 41, 42 for adjusting optical axis adjustment and made incident in a beam splitter 3. A sub beam 2b-1 branched by the splitter 43 is made incident in a photodetector 4-1 for monitor. On the other hand, a main beam 2a is made incident in an acousto-opto modulator 45 and modulated by an electric signal modulated by information, branched into the O-th order light and the primary order light, the primary light is used as the main beam 2a and the O-th order light is used as a sub beam 2b-2. The beam 2b-2 is made incident into a monitor photodetector 4-2 by a beam splitter 46. The beam 2a is led onto a recording face of a disk 20. Thus, the monitor sub beam is obtained without giving effect onto the main beam. |
