Patent ID: 6928035

Claim:
An optical pick-up comprising: a first semiconductor laser light source for emitting a light beam with wavelength λ 1 ; a second semiconductor laser light source for emitting a light beam with wavelength λ 2 ; a converging optical system for receiving the light beams emitted from first and second semiconductor laser light sources and for converging the received light beams into a microscopic spot on an optical disk; a diffractive element for diffracting the light beam reflected by the optical disk; and a photo detecting portion for receiving the diffracted light diffracted by the diffractive element and for outputting an electric signal proportional to the amount of the diffracted light, wherein the photo detecting portion comprises a photo detecting portion PD 0 for receiving a +first order diffracted light from the diffractive element, and wherein a distance d 1 between the center of the photo detecting portion PD 0 and the light emitting spot of the first semiconductor laser light source and a distance d 2 between the center of the photo detecting portion PD 0 and the light emitting spot of the second semiconductor laser light source substantially satisfy the following relationship: λ 1 /λ 2 = d 1 / d 2 .