| 摘要 |
PROBLEM TO BE SOLVED: To obtain a sufficiently satisfactory reproducing characteristic without the degradation of jitter by making an optical pickup device such a constitution that a ratio between full angle half maximums of two directions orthogonally crossing each other of the light fluxes emitted from a light source satisfies a specific equation. SOLUTION: Divergent light fluxes emitted from a semiconductor laser 1 are made to be parallel light fluxes by a collimating lens 4 to be made incident on a rohmbic beam shaping prism 11 and a ratio (θrad/θtan) between full angle half maximums of the parallel light fluxes are made to satisfy 0.8<=(θrad/θtan)<=1.6 by being passed through the prism. The parallel light fluxes pass through a polarizing beam splitter 3 and a quaterwave plate 5 to become to be in circularly polarized light states and the polarized light fluxes are made incident on a double focus objective lens. A satisfactory reproducing characteristic is obtained by allowing the shaping ratio in the beam shaping prism 11 to make the beam diameter in the radial direction of the transmission light fluxes and the beam diameter in the tangential direction of the transmission light fluxes satisfy the prescribed equation when a ratio between the full angle half maximums in the luminous flux emitted from the semiconductor light source is 3. |
