Optical pickup device and focus control method therefor

An optical pickup device that emits laser light to a signal recording medium including a label layer, the label layer being capable of recording label information in the form of a visible image through application of laser light, the optical pickup device comprising:

• a first laser light source and a second laser light source that emit first laser light and second laser light, respectively, the first laser light source and the second laser light source being arranged in different optical paths;
• an objective lens that receives the first and second laser light, the objective lens being shared by the first laser light source and the second laser light source, wherein the first laser light and the second laser light have different focal lengths from a principal point of the objective lens in accordance with a distance between a signal layer of the signal recording medium and the label layer of the signal recording medium, and when the first laser light source and the second laser light source are simultaneously driven, the first laser light and the second laser light are controlled to simultaneously focus on the signal layer of the signal recording medium and the label layer of the signal recording medium, respectively;
• and
• a beam splitter for use in providing a difference between respective optical path lengths from the first laser light source and the second laser light source to the objective lens, whereby the first laser light is caused to be incident on the objective lens in the form of collimated light, and the second laser light is caused to be incident on the objective lens with a predetermined angle of divergence.