| 摘要 |
PURPOSE:To reduce the using number of polarizers and half mirrors and to make the device small in size by guiding reflected beam light from a photomagnetic disc to a polarizing prism consisting of a quartz crystal or the like and having a fine separating angle and by detecting the output light by two photosensors. CONSTITUTION:The reflected light from the photomagnetic disc D through an objective lens 5 and a half mirror 4 is made incident to the polarizing prism 15 (Wollaston prism e.g.) consisting of crystal or the like. In case of the reflected light polarized at 45 deg. which is not affected by the disc, the quantity of light of two beams A, B outputted from the prism 15 is equalized, but if the light polarized like an ellipe by a photomagnetic effect is made incident, the quantity of light of the beams A, B may have a difference. Therefore, an information reproducing signal with high SN ratio can be obtained by finding out the differential output of two sensors S1, S2 constituting a photosensor 16. |
