| 摘要 |
PURPOSE:To reduce the parts number in an optical circuit and to obtain a small-sized optical head by varying the optical path of reflected light with a single beam splitter to divide the beam into plural optical paths and detecting each beam independently to convert into electric signals. CONSTITUTION:The light returning from the information recording medium 1 is changed into a parallel beam by an objective lens 2 and changed into the direction to a detector system by a beam splitter 3. The light to the detector system is passed through a lambda/2 plate 6, converged by a converging lens 7, and divided into two polarization components perpendicular to each other by a Walston prism 8 to give two converged spots on a photodetector 9. The photodetector 9 has sectioned detector elements, and each element independently detects the 0-order diffraction light of the returning light and the interference between the 0-order diffraction light and 1-st diffraction light, and converts the light into electric signals. In this constitution, the returning light passes through only one beam splitter 3, so that enough light quantity is given to the detector system. Moreover, since only one optical detector 9 is used, the device is easily made smaller in size. |
