US Patent 7680014 Objective optical system and optical pickup device using it
Patent 7680014 was granted and assigned to Fujinon on March, 2010 by the United States Patent and Trademark Office.
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An objective optical system is formed of a diffractive optical element with a diffractive surface formed on a virtual plane and an objective lens for focusing three collimated light beams of three different wavelengths at three different numerical apertures onto desired positions of three different recording media with substrates that include different thicknesses, such as an AOD, a DVD, and a CD, that introduce different amounts of spherical aberration in the focused beams. The objective optical system provides compensating spherical aberration to the three light beams by varying the distance between the diffractive optical element and the objective lens with the recording medium being used. The objective optical system focuses second-order diffracted light of one wavelength and first-order diffracted light of the other two wavelengths. An optical pickup device includes the objective optical system, the recording media, and a light source that provides the three light beams.
US Patent 07680014 Objective optical system and optical pickup device using it US Patent 7680014 Objective optical system and optical pickup device using it
US Patent 07680014 Objective optical system and optical pickup device using it
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