| 摘要 |
PURPOSE:To always ensure a satisfactory recording and reproducing characteristic even at the time of generating the deviation of the position of an optical part due to a change due to an elapse of time or a temperature and humidity change or the like. CONSTITUTION:Laser beam emitted from a semiconductor laser 1 is turned to a parallel light flux by a collimate lens 2, reflected by a first beam splitter 3, transmitted through a wedged prism 10, reflected by a second beam splitter 11, and a fine spot is formed on an optical information recording medium 6 by an objective lens 5. One part of the light transmitted through the second beam splitter 11 is condensed on a half-divided light receiving element 13 by a condenser lens 12, the difference between the output signals of each light receiving face 13a and 13b is detected, the wedged prism 10 is rotated so that the difference signal output Sd can be turned to 0, and the fluctuation of incident angle on the objective lens 5 due to the displacement of the semiconductor laser 1 in the right and left direction is corrected, so that the generation of the aberration of the spot can be suppressed. |
