| 摘要 |
PURPOSE:To eliminate the need for alignment between the luminous flux of positional information and the optical axis of a minutely divided plane detector and positioning of the luminous flux in the rotating direction in a plane of the detector to be performed with high accuracy, by detecting the luminous flux at minutely divided plane areas divided into nine or more areas and combining the detected luminous fluxes to roughly divided areas divided into several areas. CONSTITUTION:A luminous flux 12 of positional information exiting from a positional information light source 11 for detecting focussing servo error, etc., is made incident on a minutely divided (divided into nine or more areas) parallel output diode 13 and the output of the diode 13 is converted from signals of optical intensities of the minutely divided areas into electric signals corresponding to roughly divided areas by a minute division-to-rough division converting circuit 15 through a minutely divided parallel output signal line 14. Position detecting signals 18 are obtained from the electric signals by a positional signal combining circuit 17. Or the luminous flux 12 is inputted in an optical fiber bundle 20 and light exiting from the bundle 20 is made incident on a roughly divided detecting photodiode 21. When the luminous flux 12 is inputted in the optical fiber bundle 20, the density of the bundle 20 at the outgoing section is made rougher. Therefore, it is not necessary to make positional correction of the photodiode 21 with high accuracy. |
