| 摘要 |
PURPOSE:To suppress a deviation from the prescribed pit of a spot converged on a disk even when the oscillation wavelength of a semiconductor laser is changed by making two pieces of an anamorphic prism consisting of an optical system in a prescribed design. CONSTITUTION:A diverging luminous flux from the semiconductor 1 is made to a parallel luminous flux with an ellipse-shape crosssectional plane by a collimator lens 2, then, is made to the crosssectional plane of a circle-shape by the anamorphic prism 3, 4. Then, the flux is converged on the optical disk 8 through a routine prism 5, a rising routine prism 6 and an objective lens 7. A reflected light beam from the disk 8 is reflected partially by a half mirror prism 9, is led to a lambda/2 plate 10, a condenser lens 11 and a polarizing beam splitter 12 and polarization components (p), (s) are converged to respective light receiving elements 13, 14. By such a constitution. by making the refractive index, the vertical angle, the refracted angle of an incident end face, etc., of the prisms 3, 4 a prescribed condition, the deviation of the spot converged on the disk 8 is reduced. |
