Patent ID: 7738342

Claim:
An optical pickup device including k light emitting elements which radiate light beams having wavelengths different from one another corresponding to k optical recording media different from one another in specifications including a used wavelength, a numerical aperture (NA), and a thickness of a signal plane protecting substrate, a common objective lens which focuses the light beams radiated from the light emitting elements on the k optical recording media, which are interchangeably mounted at a predetermined location, and an optical system which transforms the light beams radiated from the light emitting elements into parallel light beams and guides the parallel light beams to the objective lens such that axes coincide with a light axis of the objective lens, characterized in that light beam restriction means and phase correcting means are located backward and forward between the optical system and the objective lens such that said phase correcting means are nearer the objective lens in relation to said light beam restriction means, said light beam restriction means propagate each of the k light beams having the different wavelengths only at a portion, and said phase correcting means correct phases of the k light beams, at least 2 k concentric toric or disciform phase correcting zones which do not overlap one another and are centered on a light axis are provided in said phase correcting means, each of the phase correcting zones exclusively performs phase correction on one of the k light beams having the different wavelengths, and said phase correcting means are configured such that each light beam undergoes phase correction in at least two of the phase correcting zones which are not adjacent to each other and are exclusive to the light beam, a plurality of transparent regions having wavelength selectivity which have respective same shapes as the phase correcting zones of said phase correcting means are provided around the light axis in said light beam restriction means, each of the phase correcting zones and a corresponding one of the transparent regions having wavelength selectivity, which have the same shape, are associated with each other, each of the transparent regions having wavelength selectivity propagates only the light beam having the wavelength, which is to be phase-corrected by the corresponding phase correcting zone, and said light beam restriction means are configured such that any one of the light beams having the wavelengths is not propagated at a region other than the transparent regions having wavelength selectivity.