CATADIOPTRIC OPTICAL SYSTEM AND OPTICAL PICKUP EMPLOYING CATADIOPTRIC OPTICAL SYSTEM AND OPTICAL DISK DRIVE AND OPTICAL DISK

摘要

PURPOSE: A catadioptric optical system and an optical pickup employing the catadioptric optical system and an optical disk drive and an optical disk are provided to reduce the size of optical components and the size of a focusing optical spot by constructing a focusing optical system forming a near field though using a laser beam having a small beam diameter. CONSTITUTION: A refracting surface(201) is provided on a side of a focusing optical system(20) and has a first curvature radius. A first reflecting surface(203) surrounds the refracting surface(201) from a side of the focusing optical system(20) and has a second different curvature radius different from the first curvature radius. A transparent beam focusing surface(204) is provided on the other side of the focusing optical system(20). A second reflecting surface(205) surrounds the beam focusing surface(204) from the other side of the focusing optical system(20). The refracting surface(201) refracts an incident light beam(10). The second reflecting surface(205) reflects the light beam(10) refracted by the refracting surface(201) toward the first reflecting surface(203). The first reflecting surface(203) focuses the light beam(10) reflected from the second reflecting surface(205) on the beam focusing surface(204) as a beam spot.