OPTICAL PICKUP COMPATIBLE WITH A PLURALITY OF TYPES OF OPTICAL DISKS HAVING DIFFERENT THICKNESSES

摘要

An optical pickup (10) having a laser light source (1) and an objective (7), wherein provided is an optical device (6) for transmitting a laser beam of 635 nm wavelength emitted from a first semiconductor laser (1A) and allowing the laser beam to fall on the objective (7) while maintaining the incident intensity of laser beam, and for selectively diffracting another laser beam of 780 nm wavelength emitted from a second semiconductor laser (1B) in a desired direction while maintaining the incident intensity of laser beam and allowing a predetermined central portion of the laser beam to fall on the objective (7), whereby the optical pickup (10) can record or reproduce a signal on or from any one of different types of disks (11, 110) having different substrate thicknesses while projecting a laser beam having an intensity strong enough to record a signal onto a signal recording surface (11a, 110a).