| 摘要 |
<P>PROBLEM TO BE SOLVED: To realize an optical pickup with no complication and no increase in the number of components by being compatible with two generations that are a large capacity blue system with little chromatic aberration deterioration due to wavelength variation and wavelength deviation and a DVD system or three generations further including a CD system. <P>SOLUTION: This optical pickup employs a phase correcting means 105 which uses an electrooptic element such as liquid crystal, controls applied voltage between a transparent electrode and a common electrode divided in a concentrically circular manner, changes the refractive index of the liquid crystal and controls transmitted light and can correct chromatic aberration caused by wavelength variation due to central wavelength deviation of a light source and temperature fluctuation. The optical pickup is further provided with an objective lens 108 having two cemented lenses constituting a single group to suppress chromatic aberration caused by wavelength variation due to light emission output fluctuation and a wavelength distribution due to multimode light emission. An aperture switching means 107 switches the diameter of an incident luminous flux in accordance with respective light sources of a semiconductor laser 101 for a blue wavelength region, a hologram unit 201 for a red wavelength region and a hologram unit 30 for an infrared wavelength region, and makes the optical pickup compatible over a plurality of generations. <P>COPYRIGHT: (C)2004,JPO |
