| 摘要 |
PROBLEM TO BE SOLVED: To provide a compatible type optical pickup, which is suitable for miniaturization and improves the utilization efficiency of light as well, by making switching possible for DVD and for CD just under completely electric control without requiring any mechanical moving mechanism, etc., at all. SOLUTION: A transmission type liquid crystal panel 4, which applies the phase difference of a 1/4 wavelength or the odd-number multiple to transmitted light and is provided with a transparent electrode 402a composed of an opening pattern 405 in any prescribed shape, is used and the liquid crystal panel 4 is arranged so that its polarizing plane can cross the polarizing plane of a polarized beam splitter 2 at any prescribed angle. The voltage to be applied to the transparent electrode 402a is controlled so that the entire surface of the liquid crystal panel 4 can become a 1/4 wavelength board when reproducing and recording DVD but only the section of the opening pattern 405 can become the 1/4 wavelength board when reproducing CD. |
