| 摘要 |
PROBLEM TO BE SOLVED: To effectively avoid the deterioration of various characteristics and to make accessible to plural kinds of optical information recording media with a simple constitution by largely limiting the beam diameter of a laser beam by an aperture in a direction nearly orthogonal to the scanning direction of the laser beam compared with the direction corresponding to the scanning direction of the laser beam in the optical information recording medium. SOLUTION: Laser beams LA, LB exited from a laser diode 2 and an optical integrated element 4 via a beam splitter 5 are made incident on a collimetor lens 12, are converted into nearly parallel light beams by the collimetor lens 12 and are exited to an objective lens 9. The incident surface side of the collimetor lens 12 is made of a nearly flat surface, and a dielectric film is laminated on the flat surface in the prescribed shape to make a light shielding film 12A having wavelength selectivity. an aperture 12B limiting the beam diameter of the laser beam LB in a direction orthogonal to the scanning direction of the laser beam LB compared with the direction corresponding to the scanning direction of the laser beam LB is constituted of the light shielding film 12A. |
