| 摘要 |
PURPOSE:To simplify a circuit at the low cost and to ensure the quality of RF signals by using a luminous flux splitting means that transmits the central area of luminous flux reflected from a recording medium and reflects outside area and light detecting elements divided to detect TE signals and RF signals independently. CONSTITUTION:Reflected luminous flux from a track 38 passes through a diaphragm lens 37, a 1/4 wavelength plate 36 and a total reflection mirror 35, and reflected by a polarization beam splitter 34, and splitter to luminous fluxes 42, 43 reflected by reflecting mirrors 40, 41 and a transmitted luminous flux 44. The quantity of light projected on focusing error detectors 48B-51B is made to the necessary minimum and the quantity of light projected on tracking error detector 52B, 53B is also made to the necessary minimum. That is, remaining quantity of light of luminous flux is projected on an RF signal detector 54B, and RF signals are made by an RF signal circuit 57. An FE signal circuit 55 and a TE signal circuit 56 can take out respective detector output in form of current, and accordingly, the influences of temperature drift of a differential amplifier to offset voltage on the output becomes very small. |
