| 摘要 |
PURPOSE:To provide an optical pickup device, of which assembly or the like is facilitated and in which tracking servo is made possible by a three-beam method, by splitting a laser beam with a transmission type diffraction grating and converging the reflected beams with a hologram element. CONSTITUTION:A three-dividing transmission type diffraction grating 12 splits forward emitted light emitted from a semiconductor laser element 11 into three zero-order and + or - first-order diffracted beams and guides them forward. A hologram element 13 transmits three beams, and guides them to an optical disk 15 through an objective lens 14. Concerning three beams reflected on the disk 15, optical axes are changed by first-order diffraction, the operation to converge those beam so that focal distances can be made different in one direction orthogonal to the advancing direction of the beam and a direction orthogonal to this one direction within the same plane, and they are converged onto a photodetector 10 for signal detection. Thus, a laser element 11, photodetector 10, diffraction grating 12 and hologram element 13 can be arranged on the same plane of one base 1 and assembly or adjustment can be facilitated. |
