| 摘要 |
PURPOSE:To remove noise from a laser light source and to obtain a high level information signal by obtaining a fluction signal of the polarized quantity of the laser light source and tracking and focusing error signals through an optical beam splitter. CONSTITUTION:An optical beam projected from the laser light source 31 is converted into a true circle beam by a prism 33 through a colimating lens 32 and divided into two beams by a beam splitter (BS)35 through a polarizer 34. The light reflected by the BS35 is inputted to an automatic output control device 36 to remove a fluctuation noise of the polarized angle of the laser light source 31 from the inputted light. The optical beam transmitted through the BS35 is focused on a photomagnetic medium layer 38 by an objective lens 37. The reflected light is reflected by the BS35, divided into two beams by an Wollaston prism 39 and made incident to two-division detectors 41, 43 and 45, 47 through condensing lenses 40, 44 and reflectors 42, 46, so that tracking and focusing error signals are obtained through differential amplifiers 48-50. |
