| 摘要 |
PURPOSE:To simplify and scale down a structure by providing a beam state converting means which changes the advancing direction and converged state of some of light beams introduced to a photodetector through an objective lens. CONSTITUTION:Since a laser beam L is divided into the 1st laser beam component L1 of an out-of-focus detecting system and the 2nd laser beam component L2 of a track deviation detecting system with the use of a light sampling member 7, an out-of-focus detecting spot and a track deviation detecting one can be away each other on a photodetector 9 in terms of a geometric position, and mutual influence can be eliminated. Moreover the detection of the out-of- focus and track deviation can be made by one mechanically integrated photodetector 9, and simultaneously a half prism, etc., can be made unnecessary. Thus the number of optical parts and the cost are reduced to scale down the device, and furthermore assembly and adjustment can be done easily, thereby manufacturing the titled device in a short time. |
