| 摘要 |
PURPOSE:To obtain an optical head capable of easily separating the detected light flux and stabilized in the detection of an error signal or converging performance by adjusting a distance between a collimeter lens and a light source in the optical axis direction, coupling the collimeter lens with a member having a low thermal expansion, and fixing the member on an optical head material only in one plane vertical to the optical axis. CONSTITUTION:A semiconductor laser 1 is fixed on a low expansion member 2, the collimeter lens 2 is also fixed on a holder 22 for the low expansion member 21 and the distance between the laser 1 and the lens 2 is fixed on a chassis 20 only in one plane vertical to the optical axis of divergent light flux 30 under the status thermally stabilized and precisely positioned by screwing between the member 21 and the holder 22 and the pressure of an elastic member 23. Thereby, the change of the distance between the laser 1 and the lens 2 due to the thermal expansion of the chassis can be removed and parallel light beams 31 can be always stably irradiated, so that a focus error or a tracking error can be stably detected.
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