| 摘要 |
PURPOSE:To prevent the deterioration of S/N by unifying a beam splitter separating reflecting light and a beam splitter separating an optical magnetic signal detecting system and a servo signal detecting system, and making both into a composite beam splitter. CONSTITUTION:A reflecting light from recording media 6 is reflected by the (a) surface of a composite beam splitter 3, the light transmitted (b) surface is guided through a convex lens 7 and a cylindrical lens 8 to a light detecting device 9 and a focus error and a track error are detected. The light to reflect the (b) surface enters a polarizing beam splitter 10, the light to transmit the polarizing beam splitter 10 is guided to a light detecting device 11, the light to reflect is guided to a light detecting device 12 and the output difference of light detecting devices 11 and 12 comes to be an optical magnetic signal. AS the result, the composite beam splitter 3 is emitted, the light, which comes to be the optical magnetic signal, reflects (a) and (b) surfaces, the phase difference comes to be approximately '0', and the deterioration of the S/N is prevented. |
