| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup device compatible with different optical information recording media by using luminous flux of same wavelength. <P>SOLUTION: When a recording or reproducing operation is carried out with respect to a 1st optical information recording medium, the luminous flux is made to be an ordinary ray polarization by a switching means. Since refractive indexes of a double refraction medium layer and of a homogeneous refractive index transparent material become the same when the ordinary ray polarization is incident to an objective optical element OBJ1, the original optical property of objective optical element is maintained without generating the change of transmission wave surface of the objective optical element OBJ1. Meanwhile, when the recording or reproducing operation is carried out with respect to a 2nd optical information recording medium, the luminous flux is made to be an abnormal ray polarization by the switching means. Since the refractive indexes of the double refraction medium layer and of the homogeneous refractive index transparent material are different when the abnormal ray polarization is incident to the objective optical element OBJ1, the abnormal ray polarization is diffracted at a saw-tooth uneven section, and the transmission wave surface is changed in accordance with this diffraction, then a divergent angle or convergent angle is changed. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
