Patent ID: 6222812
Filing Date: 2001-04-24
Classification: G02B,G11B

Abstract:
An optical pickup apparatus for at least two optical recording media, which are different in distance from an optical pickup to an information recording surface and using light beams having different wavelengths for recording and reading information, the optical pickup apparatus comprising:a plurality of laser light sources for emitting a first light beam having a relatively shorter wavelength and a second light beam having a relatively longer wavelength, respectively;an objective lens having a predetermined focal length, in which a focal point of said objective lens according to the first light beam coincides with a position on the information recording surface in a first optical recording medium;means for optical detection;means for controlling an optical path so that at least one of the first and second light beams emitted from one of the laser light sources is directed to said objective lens and light output from said objective lens is directed to said optical detection means; andmeans for phase shifting, located between said optical path control means and said objective lens, for shifting the phase of a portion of the second light beam proceeding from said optical path control means to said objective lens, thereby reducing a size of a beam spot which is formed on the position of the information recording surface in the second optical recording medium by the second light beam focussed with said objective lens,wherein the wavelength of one of the first and second light beams is chosen according to the optical recording medium to be used.