Patent ID: 7986607
Filing Date: 2011-07-26
Classification: G11B

Abstract:
1. An optical pickup for emitting light toward an optical disc, receiving the light that has been reflected from the optical disc, and outputting a signal representing intensity of the reflected light, the optical pickup comprising: three light sources for emitting three light beams that are linearly polarized and have wavelengths λ at least one lens for condensing the light beams that have been emitted from the three light sources; a photodetector for receiving the light beams that have been reflected from the optical disc; and a wave plate, which is arranged on an optical path to be followed by all of the light beams emitted from the three light sources both on their way toward the optical disc and on their way back from the optical disc toward the photodetector, wherein the wave plate has first and second layers, of which the retardations and optic axis directions are different from each other, and wherein sum of the retardations of the first and second layers is defined to be approximately 5/4 λ wherein there is a difference in optic axis direction between the first and second layers, and wherein by taking advantage of the difference in optic axis direction, the linearly polarized light beams with the wavelengths λ