ACTIVE COMPENSATION DEVICE, AND COMPATIBLE OPTICAL PICKUP AND OPTICAL RECORDING AND/OR REPRODUCING APPARATUS EMPLOYING THE ACTIVE COMPENSATION DEVICE

摘要

An active compensation device, and a compatible optical pickup and an optical recording and/or reproducing apparatus employing the active compensation device, are compatible with information storage media standards specifying different thicknesses and light having the same wavelength. The active compensation device includes two transparent substrates; a material layer interposed between the transparent substrates and having a refractive index that is actively switched according to a voltage applied to the material layer; and a holographic pattern formed adjacent to the material layer on a surface of at least one of the transparent substrates to control a divergence angle of incident light by transmitting the incident light without diffraction or diffracting the incident light according to the refractive index of the material layer.