| 摘要 |
PURPOSE:To increase the sensitivity of a reproducing signal and a servo signal by using a beam splitter in stead of a half mirror to separate signal reproducing light from servo signal light. CONSTITUTION:Reflected light from an optomagnetic medium 5 is separated by a beam splitter 16 and sent to the 2nd beam splitter 17 to be separated into signal reproducing light 18 and servo signal light 19. If the matrix displays of the beam splitters 16, 17 are defined as A and B, formulas I and II are applied to the transmitted light and reflected light respectively. If the polarized state on a photodetector 13 is E+M when the magnetization of the medium is ascending and E-M at the time of descending magnetization, Ps=¦(E+M)<2>-(E-M)<2>¦ is detected as a signal component, so that the beam splitter 16 having 66% and 0% transmissivility of P and S components is optimum. In the servo signal light, the beam splitter 17 having 100% reflection factor of the S component is required. In respect of the (p) component, an optimum value is selected in accordance with the servo system or the like. |
