| 摘要 |
PURPOSE:To completely remove astigmatism and further to reduce cost while easing the work accuracy of a light element by setting the astigmatism of a light flux in a position out of an optical anamophic optical system to an amount to cancel the astigmatism to be generated in the optical system in a rear step by adjusting an internal between a light source and a collimator optics. CONSTITUTION:In the optical system in the rear step rather than an anamorphic prism 13, a fixed mirror 15, beam splitter 20, movable mirror 16 and objective lens 17 are arranged. The astigmatism to be generated in these optical systems in the rear step is canceled with the astigmatism in the position out of the anamorphic prism 13 by adjusting the interval Z between a laser diode 11 and a collimator lens 12 and the astigmatism of the light flux to be converged to a magnetooptical disk 1 is corrected to zero. Thus, since the astigmatism is removed on the storing medium, the manufacture cost can be reduced by easing the work accuracy of each optical element in the optical system in the rear step. |
