Patent ID: 7403453

Claim:
An optical pickup apparatus compatible with a first optical recording medium adapted for a first wavelength for writing and reading and a second optical recording medium adapted for a second wavelength for writing and reading, comprising: a first light source emitting a first beam at the first wavelength; a second light source emitting a second beam at the second wavelength; a coupling lens for coupling one of the first beam and the second beam; an objective lens for converging the coupled beam so as to form a beam spot on a recording surface of one of the first optical recording medium and the second optical recording medium; optical path separating means for separating a return beam reflected by the optical recording medium and transmitted through the objective lens, from an upstream optical path leading from the light source to the objective lens, the optical path separating means being provided in alignment with both an upstream beam traveling to the recording surface and the return beam; detecting means for receiving the return beam separated by the optical path separating means so as to retrieve information from the return beam, the detecting means being provided in alignment with both the upstream beam and the return beam and including photosensitive means; control means for effecting focusing control and tracking control based on a result of detection by the detecting means; and optical axis aligning means for aligning optical axes of the first beam and the second beam with an optical axis of the coupling lens, wherein: the first light source is driven only when the first optical recording medium is used, the second light source is driven only when the second optical recording medium is used, the coupling lens comprises an anamorphic lens which provides different actions in a direction in which an angle of divergence with respect to intensity of the beam from the light source is maximum and in a direction in which the angle divergence is minimum, and which is provided with a collimating function for collimating one of the first beam and the second beam and a beam shaping function for shaping one of the first beam and the second beam, the optical axis aligning means comprises: a prism element provided with a first film having one of a variable transmissivity and a variable reflectivity that depends on a polarization of the beam, and a second film having a polarization filter characteristic that depends on a wavelength of the beam, and the optical pickup apparatus further comprises: a phase plate for operating as a ¼ wave plate for the first beam and the second beam; the prism element and the phase plate constitute the optical path separating means by controlling the return beam to be incident on the photosensitive means of the detecting means via the coupling lens, the phase plate and the prism element, and the photosensitive means and the coupling lens constitute the detecting means.