OPTICAL PICK-UP DEVICE

摘要

PURPOSE: An optical pick-up device is to use laser beam having two different wavelengths in a short wavelength range, and efficiently compensate generation of aberration due to the rapid change in a reflective index of an optical material. CONSTITUTION: The first and second light source(600,700) respectively generates laser beam having a different wavelength. An objective lens(200) condenses the laser beam from the light source into a media(100). The first and second light detecting portion respectively receives the laser beam reflected by the media. A collimating lens(400) is disposed at an optical path through which the laser beam having a relatively short wavelength is passed. The collimating lens has a negative lens(402) having negative power and a positive lens(401) having positive power. The collimating lens collimates the laser beam from the first and second light source and also compensates chromatic aberration. A wavelength selecting filter(300) is disposed on an optical axis adjacent to the objective lens. The first light source generates the laser beam having about 400 nm. The second light source generates the laser beam having about 650 nm.