Patent ID: 7764587

Claim:
An optical pickup apparatus of plural-wavelength and single-lens type wherein a plurality of sorts of optical discs of different wavelengths for use are coped with by a plurality of laser light sources which emit laser beams of wavelengths different from each other, and a single objective lens, comprising: a beam shaping mirror which is included in optical paths between the objective lens and the plurality of laser light sources, and which causes each of the laser beams to be incident on a transmission surface, reflects the laser beam from a reflection surface being unparallel to the transmission surface and causes the laser beam to emerge from the transmission surface, thereby to convert a light intensity distribution of the laser beam of each of the wavelengths from an elliptic shape into a circular shape; wherein said beam shaping mirror is made of a liquid crystal which forms the transmission surface and the reflection surface in a predetermined filled-up state, and the liquid crystal is electrically driven so that a refractive index of the liquid crystal is held constant irrespective of the wavelengths of the laser beams which enter said beam shaping mirror.