Patent ID: 8477583

Claim:
An optical pickup, comprising: at least one light source for selectively emitting three light beams having blue, red, and infrared wavelengths, respectively; and an objective lens arranged so that each of the three light beams enters thereto, wherein the objective lens has a blazed grating structure, the blazed grating structure comprising: a first grating having phase steps arranged concentrically around a center axis of a lens in a region in which all the three light beams pass, for diffracting the three light beams having the blue, red, and infrared wavelengths in a 2 nd order, a 1 st order, and a 1 st order, respectively; and a second grating formed in the same plane as the first grating and having phase steps arranged concentrically around the center axis of the lens in the region in which all the three light beams pass at positions different from positions of the phase steps of the first grating, for diffracting the three light beams having the blue, red, and infrared wavelengths in a 1 st order, a 1 st order, and a 1 st order, respectively, and wherein the objective lens diffracts the three light beams having the blue, red, and infrared wavelengths in a 3 rd order, a 2 nd order, and a 2 nd order, respectively.