| 摘要 |
PURPOSE:To improve the tracking adjustment and focus adjustment of an optical head remarkably by separating reflected light from a disk into a center and a circumferential light beam through an optical part where a reflective and a transmissive part are formed nearly concentrically. CONSTITUTION:A reflected beam reflected by the recording surface of the optical disk is made into a parallel beam through a convergent lens and the parallel beam is sent to a polarization beam splitter 33 through a quarter-wavelength plate 34. Then, the reflected beam is portioned out by the beam splitter 33 and sent to the optical part 37 consisting of the reflective part 37a and transmissive part 37b. This optical part 37 is arranged at up to 45 degrees to the optical axis of an optical path of reflection as shown in the figure, and while the relatively gentle light intensity distribution in the section of the reflected beam due to an off-tracking phenomenon is considered, the reflected beam is separated into the center light beam near the optical axis and the circumferential light beam at the outside of the center light beam, which are distributed in two directions respectively. |
