| 摘要 |
PURPOSE:To contrive the miniaturization of an optical head and the reduction in weight without wasting a detected light interrupted with a knife edge by composing a turning direction of a compensating plate and a polarized beam splitter arranged in the optical path of the detected light and composing a knife edge means of the edge of the compensating plate. CONSTITUTION:The optical head is provided with the turning means to turn a part of a detected light 8 in a different direction, the knife edge means provided on one of optical paths for detecting a focus error condition, etc. The turning means is composed of the compensating plate and a polarized beam splitter 2 arranged in the optical path of the detected light 8, and the knife edge means is composed of an edge 17 of the compensating plate. For the compensating plate, a lambda/2 plate 12 is used. Thus, since the turning means and knife edge means are provided in the optical path of the detected light 8, both can be unified, a part of the detected light 8 cannot be interrupted by the knife edge means, and the optical head can be miniaturized and, simultaneously, reduced in weight. |
