| 摘要 |
PURPOSE:To excellently read information regardless of the secular fluctuation in a plane of polarization and a polarization ratio in a high power LD by reflecting major part of an S polarization component from a light source side by a polarization reflecting film and almost transmitting a beam in the direction orthogonally intersecting with a polarizing direction. CONSTITUTION:The beam radiated from an LD unit 1 transmits through a coupling lens 2, and becomes a substantial parallel luminous flux whose luminous flux sectional shape is (an elliptic shape making a direction orthogonally intersecting with a figure a major axis direction) by the lens 2. The luminous flux is made incident on a beam shaping surface 3A of a beam shaping element 3, and is refracted and beamed by the beam shaping surface 3A. The incident beam on the shaping surface 3A is totally reflected further in the inside of the beam shaping element 3, and is made incident on the polarization reflecting film 4A. The film 4A is transmitted by a required part of a P polarization component linearly polarizing in the direction parallel to an incident surface on the shaping surface 3A and some part of the S polarization component orthogonally intersecting with the P polarization component with a polarizing beam splitter. Thus, excellent reading is performed in spite of the fluctuation in the plane of polarization. |
