| 摘要 |
PURPOSE:To minimize the off tracking of return light and to miniaturize the title device by providing a converging means to converge a converged laser beam on an optical disk recording face and detecting means to respectively detect quartered light flux. CONSTITUTION:The light reflected by an optical disk recording face 6 passes through a diaphragm lens 5 and 1/4 wavelength plate 4 again, reaches a polarizing beam splitter 3 and goes straight on through this. This return light 10 to go straight is narrowed down by a convex lens 7, passes through two parallel plates 8A and 8B and thus, it is level-divided into four. In this case, a difference occurs in the light quantity of the return light on light receiving elements 9C and 9D to the light quantity of the return light on light receiving elements 9A and 9B and a TE signal is generated. Consequently, by obtaining the difference signal of the outputs of adding amplifiers 11A and 11B by a differential amplifier 12A, a tracking error signal can be obtained. Thus, the return light is not deflected, a focus error signal and the tracking error signal can be detected by one photodetector and the title device is miniaturized. |
