| 摘要 |
PURPOSE:To obtain a compact and light-weight optical pickup by setting a light source and plural photodetectors on a monolithic substrate and adding an error signal detecting hologram between the monolithic substrate and a luminous flux dividing hologram. CONSTITUTION:For instance, a 2nd hologram 12 divides the light returned from a recording medium 3 into a beam for detection of the focus error signal and a beam for detection of the tracking error signal. These divided beams are received by different photodetectors 5A-5C. Thus both focus and tracking error signals are detected independently of each other with no mutual interference. Furthermore a semiconductor laser 2 and those photodetectors 5A-5C are set on a monolithic substrate 6. Then the 3rd and 4th error signal detecting holograms 13 and 14 are set between the substrate 6 and the hologram 12. In such a constitution, a compact and light-weight optical pickup 1 is obtained. |
