Patent ID: 6125091
Filing Date: 2000-09-26
Classification: G11B

Abstract:
An optical pickup apparatus comprising:a first semiconductor laser emitting a first laser beam having a first wavelength, said first laser beam being one of a P- and S- polarized light beam;a first beam splitter partially reflecting or transmitting in a predetermined direction the first laser beam emitted by said first semiconductor laser;a second semiconductor laser emitting a second laser beam having a second wavelength, said second laser beam being the other of said P- and S- polarized light beam, said first and second wavelengths being different;a second beam splitter partially reflecting or transmitting in said predetermined direction the second laser beam emitted by said second semiconductor laser;a single collimator lens positioned to receive both the first laser beam reflected or transmitted by the first beam splitter and the second laser beam reflected or transmitted by the second beam splitter;a single objective lens focussing the first and second laser beams passing through the collimator lens onto a recording medium;a single photodetector positioned to receive reflected first and second laser beams reflected by said recording medium of said first and second laser beams;said first beam splitterhaving formed thereon a first reflective portion for partially reflecting substantially half of the first laser beam emitted from said first semiconductor laser and and for transmitting substantially all of the second laser beam emitted from said second semiconductor laser beam;said second beam splitter having formed thereon a second reflective portion for partially reflecting substantially half of the second laser beam emitted from said second semiconductor laser and and for transmitting substantially all of the first laser beam emitted from said first semiconductor laser beam,said first and second beam splitters, collimator lens, objective lens, and photodetector being positioned to form a single return path of light reflected from said recording medium, said first and second semiconductor lasers being placed in conjugate with said photodetector and said collimator lens so that both of said beams reflected by said recording medium are detected by said photodetector.