| 摘要 |
PURPOSE:To reduce the number of parts and a cost, to miniaturize and to reduce the weight of an optical system by reflecting a light which is incident on a polarizing beam splitter with a polarization separating surface and a reflecting surface, separating the light to two rays of light and irradiating a light receiving surface, which is quadri- divided, with the separated rays of light. CONSTITUTION:On the optical paths of the rays of light which are reflected and separated to the two rays of light by a polarization separating surface beta and a reflecting surface alpha of a polarizing beam splitter 28, a photodetector 31 having light receiving surfaces (a)-(d), which are divided into plural surfaces by dividing lines, are arranged so that a dividing line L in a horizontal direction can be form a fixed angle to a surface which links the optical axes of the two rays of light. Accordingly, the reflected rays of light to be reflected by an optical information recording medium 24 and led into an optical information detecting system 25 are respectively reflected by the polarization separating surface beta and reflecting surface alpha and separated to the two rays of light. Then, since the quadri-divided light receiving surfaces of the photodetector 31 are irradiated with these separated rays of light, a focus error signal, a track error signal or a signal for regeneration can be detected. Thus, the number of the parts can be reduced and the device can be miniaturized. |
