| 摘要 |
PURPOSE:To achieve a stable emission control by preventing a light emitting power from varying by a return light in a semiconductor laser or the like of a tracing type optical pickup. CONSTITUTION:A phase difference plate 11 of (lambda/4)Xn is provided between semiconductor laser 1 and a polarized beam splitter 3. Light output varying portion detecting means 13 and 14 are provided which receive a laser light reflected (transmitted through) on the polarized beam splitter 3 to detect an output varying portion of the laser light. This enables monitoring with a simple construction only having a phase difference plate without altering optical characteristic of the conventional optical part thereby obtaining a stable light output regardless of the existence of the return light. |
