| 摘要 |
PURPOSE:To provide optical system members which are light in weight and are simple and to allow response with a small size by adhering a quarter-wave plate which shifts the phase of collimated beams of light transmitted through a polarizing beam splitter to the optical disk side of the polarizing beam splitter. CONSTITUTION:The direction of linearly polarized is changed by 90 deg. from the direction at the time of incidence when the light reflected from a disk 9 passes the quarter-wave plate 4. The total light quantity of the reflected light from the disk 9 is refracted to a photodetector 7 side without returning to a laser diode 1 side by the polarizing beam splitter 3. This quarter-wave plate 4 is adhered to the surface on the objective lens 5 side of the polarizing beam splitter 3 to reduce the thickness of the head. A costly collimation lens, objective lens and cylindrical lens can, therefore, be formed of inexpensive micro Freshnel lenses. The number of parts is decreased and the labor for optical axis adjustment is saved. The formation of the head for information optical and reproducing to the smaller size and thickness is possible in this way. |
