| 摘要 |
PURPOSE:To decrease the number of parts and to make the title device inexpensive, miniature and light by using lights guided respectively to a 2-divided photodetector and a 4-divided photodetector. CONSTITUTION:A hologram 27 whose groove intervals are different is provided on the light path of reflected light reflected by an optical information recording medium, a 2-divided photodetector 29 is provided on the light path of the transmitted light transmitted through the hologram 27 and converged and a 4-divided photodetector 31 is provided on a light path L1 of the diffracted light diffracted by the hologram 27 and converged. The transmitted light transmitted through the hologram 27 is received by the 2-divided photodetector 29, a tracking servo is executed, the diffracted light diffracted by the hologram 27 is received by the 4-divided photodetector 31 and a focus servo is executed. Further, total quantities of received light received by the 2-divided 29 and the 4-divided photodetector 31 are compared and a magneto-optical detection is executed. Thus, the number of parts can be widely decreased and the title device is can be made inexpensive miniature and light. |
