Patent ID: 8441908

Claim:
An optical pickup device comprising: a semiconductor laser element for emitting a laser light; a polarization optical system for converging, the laser light emitted from the semiconductor laser element onto a signal recording surface of an optical disc; and a photodetector for detecting returning light which returns from the signal recording surface through the polarization optical system, wherein the semiconductor laser light element is arranged so as to emit light having a predetermined polarization intensity ratio, the polarization optical system includes a beam splitter and a raising mirror on each of which a layered member is formed, where the layered member controls polarized light intensities and a phase difference of the laser light entering thereto to convert the laser light into a circular polarized light, and the optical pickup device satisfies the following expressions: Ep>Es, Rs 1 >Rp 1, 60 ≦Rs 1≦100, 0.95 ≦EsRs 1 Rp 2 /EpRp 1 Rs 2≦1.05, 90(2 n− 1)−10≦|δ1−δ2|≦90(2 n −1)+10( n= 1,2), where Es and Ep are intensities of S-polarized light and P-polarized light of laser light emitted from the semiconductor laser element, with respect to the beam splitter, respectively, Rs1 and Rp1 are reflectances (%) of S-polarized light and P-polarized light on the beam splitter, respectively, δ1 is a reflection phase difference)(°) obtained by subtracting a phase of S-polarized light from a phase of P-polarized light after the S-polarized light and the P-polarized light are reflected on the beam splitter, Rs2 and Rp2 are reflectances (%) of S-polarized light and P-polarized light on the raising mirror, respectively, and δ2 is a reflection phase difference (°) obtained by subtracting a phase of S-polarized light from a phase of P-polarized light after the S-polarized light and the P-polarized light are reflected on the raising mirror.