| 摘要 |
PURPOSE:To prevent the distribution of the quantity of incident light from changing considerably even if an objective is moved, by making the moving direction of the objective coincident with the direction of an exit angle theta of a semiconductor laser. CONSTITUTION:The p-n junction face of a semiconductor laser 11 as a light source which is arranged in the focus position of a collimation lens 3 approximately is provided orthogonally to an optical information recording carrier (disc) 7, and the exit light from the semiconductor laser 11 passes a non-polarizing beam splitter 12, where a dielectric multilayered film or a metallic thin film is formed on a diagonal face 121, and is converted to parallel light by the collimation lens 3 and passes a mirror 5 and is focused as a minute spot on a track 71 on the recording face of the optical information recording carrier 7. This minute spot is formed as a spot 13 which is narrow and long in the lengthwise direction of the track 71 and is indicated by oblique lines. A part of the reflected light from the track 71 is condenced by an objective 6 and passes the course of exit from the semiconductor laser 11 and is reflected on the non-polarizing beam splitter 12 and passes a detecting optical system 8 and is converted to an electric signal by a photoelectric transducer 9. |
