| 摘要 |
A compatible optical pickup including an active compensation device to actively switch an angle of incidence of the light on the objective lens when either a third information storage medium that has a different format than that of the first and second information storage media, or the second information storage medium is adopted for use in a data recording/reproducing operation. The active compensation device includes a plurality of transparent substrates, and at least one material layer, interposed between the plurality of substrates, having a refractive index which is actively switched according to an applied voltage. A holographic pattern, formed adjacent to the material layer on a surface of at least one of the transparent substrates, changes a divergence angle of the light by diffracting or transmitting without diffraction the incident light according to change of the refractive index of the material layer. The voltage applied to the material layer is adjusted according to the applied information storage medium that is adopted for the use in the data recording/reproducing operation.
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