| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the disorder in which liquid crystal molecules irregulary move and to provide a desired phase difference by tilting a liquid crystal panel with respect to the optical axis of an objective lens for the amount of a liquid crystal molecular pretilt angle. SOLUTION: The optical pickup has a liquid crystal panel 4 which is located between an objective lens 5 and a laser light source 1 and gives a prescribed phase difference to transmitted light beams. The panel 4 is tilted with respect to the optical axis of the lens 5 for a pretilt angle θ of the liquid crystal molecules. Thus, the liquid crystal molecules are arranged perpendicular to the axis while no voltage is applied to the panel 4 and the entire surface of the panel 4 or a circular opening pattern portion acts as a perfect quarter wavelength plate. Thus, the utilization rate of the light beams is improved, no unwanted light beams leak to a photodetector 8 and the S/N is improved. |
