Patent ID: 7978400
Filing Date: 2011-07-12
Classification: G02B,G11B,H04N

Abstract:
1. An optical pick-up apparatus, comprising: a light source unit; a light-receiving unit; an objective lens facing an optical recording medium; and an optical system having a function leading output light from said light source unit to said objective lens and a function of condensing light reflected from said optical recording medium to said light-receiving unit, wherein said optical system is provided with a varifocal lens including: a pair of optically transparent members; a first liquid having optical transparency in addition to conductivity or polarity while being held between said pair of optically transparent members; a second liquid having optical transparency in addition to insulation properties or non-polarity, where the refractive index of said second liquid is different from the refractive index of said first liquid, while being held between said pair of optically transparent members without mixing with said first liquid; a first electrode and a second electrode that apply voltage to said first liquid while being held between said pair of optically transparent members; a dielectric layer formed by oxidation of the surface of said first electrode on the side of said liquid; and a voltage-applying unit that applies a voltage signal between said first electrode and said second electrode, where said voltage signal is periodically changed between a first voltage of zero (0) volt or more and a second voltage of larger than said first voltage.