An optical pickup apparatus includes a wavelength selecting numeral aperture limiting element and a wavelength selecting beam splitter to record data on and reproduce data from three different optical discs, such as CD, DVD, and HD-DVD, each having different thickness of a protective layer and information...http://www.google.ca/patents/US20030185136?utm_source=gb-gplus-sharePatent US20030185136 - Optical pickup apparatus having wavelength selecting numerical aperture limiting unit and wavelength selecting beam spilitter
