Patent ID: 6873591

Claim:
An optical pickup device comprising: a first light source that emits first light; a second light source that emits second light with a wavelength different from a wavelength of the first light; and a step-like diffraction element that deflects one of the first light and the second light to match optical axes of the first light and the second light, the step-like diffraction element defining a light incident face and a light emitting face, one of the incident face and the emitting face having multiple sets of step-like grating faces, wherein, when a wavelength λ 1 of the first light is longer than a wavelength λ 2 of the second light, a step difference between adjacent ones of the step-like grating faces has a measurement that generates a phase difference corresponding to one wavelength for the first light, and the number of steps of each of the multiple sets of step like grating faces is set at an integer that is closest to a value α that satisfies an expression of λ 2/λ1=α/(α+1).