| 摘要 |
PURPOSE:To prevent loss of laser power and the generation of a diffraction fringe by arranging plural cylindrical lens for laser beam shaping in the middle of an optical path, and adjusting the shape of a laser beam on a recording medium. CONSTITUTION:Cylindrical lenses CL1 and CL2 are arranged between a beam expander 4 and a rotary polygon mirror 5 to correct the inclination angle of the rotary polygon mirror 5 and also to make the shape of the beam which illuminates the recording medium 7 elliptic long in a subscanning direction; the distance D between the cylindrical lenses CL1 and CL2 is varied to focus the laser beam on the recording medium 7. Then, focal lengths f1 and f2 of the cylindrical lenses CL1 and CL2 or the distance D is varied to vary the height of the Y- directional diameter of the laser beam on the recording medium 7 freely, and also to adjust the X-directional diameter of the laser beam to desired length. |
