| 摘要 |
PURPOSE:To obtain the optical head by which recording and reproducing can be carried out to both sides of the optical disk by irradiating both sides of the optical disk simultaneously with two optical beams split from an optical beam from one light source. CONSTITUTION:The optical beam 3 transformed to be a parallel beam after being emitted from a semiconductive body laser 1 is linearly polarized in the direction of B1 parallel to a paper surface and is made incident on 1/2 wave length plate 17. The crystal axis of the wave lengthplate 17 is inclined for only theta against the arrow B1 at a rotating means 16. Therefore, the optical beam 3, which is transmitted through the 1/2 wave length plate 17 as is shown by the arrow B2 has its direction of polarization rotated for 2theta, and is made incident on a polarization optical beam splitter 4. The optical beam 3 has its intensity divided by the splitter 4 and become the optical beams 3a and 3b. By selecting a rotational angle theta by the rotation means 16 of the crystal axis of the 1/2 wave length plate, the optical beam of one semiconductive body laser can be divided into two optical beams. That is, by bringing the rotation angle theta of the 1/2 wave length plate close to 0 degrees when recording side A, and bringing the rotational angle theta close to 45 degrees when a side B is recorded, the recording of side A and side B can be carried out without turning over the optical disk. |
