Patent ID: 7405383
Filing Date: 2008-07-29
Classification: G02B,G11B

Abstract:
1. An optical pickup device for writing and reading signals to and from disc-shaped recording media having different recording densities comprises: first, second, and third light sources for emitting light beams of different wavelengths, wherein, of those different wavelengths, the wavelength of the light beam of the first light source is shortest and the wavelength of the light beam of the third light source is longest; a holographic element for dividing incoming light into zero-order diffraction light and first-order diffraction light; a first photodetector for receiving the zero-order diffraction light from the holographic element to obtain an RF signal and a tracking error signal; a beam splitter for changing an optical path of a light beam coming from the first light source, the second light source, or the third light source toward a recording medium and matching an optical axis of the changed optical path with an optical axis passing through the holographic element and the first photodetector, while directing reflected light from the recording medium to the holographic element; and a second photodetector for receiving the first-order diffraction light from the holographic element to obtain a focusing error signal.