| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the need for optical elements for shaping the cross-section of a laser beam, and to make an optical pickup small in physical size and low in cost. SOLUTION: Semiconductor laser 31 radiates a laser beam outputted from a laser chip 51 through a cover glass 53 of a package 54. A cover glass is composed of a single glass material having a spherical surface on the near side of the laser chip 51 and a cylindrical surface on the further side therefrom, and is arranged so that the axial direction of the cylindrical surface becomes parallel with an active layer of the laser chip 51 and also the center of the spherical surface coincides with the emitting point of the laser chip 55. The beam diameter of the laser beam LB emitted from the laser chip 51 is magnified in the axial direction of the cylindrical surface of the glass material by passing through the cover glass 53 and the cross section is reformed. The optical pickup is able to eliminate the need for an anamorphic prism for reforming the cross section of the laser bean LB, and permits to simplify the composition and achieve the reduction in physical size and cost. |
