Optical information storage apparatus and optical device

摘要

There is disclosed a small lightweight optical information storage apparatus which can obtain a sufficient writing light quantity, and an optical device (250) used in an optical head of the information storage apparatus. The optical device (250) comprises a splitting surface (251) constituted of a part of a cylindrical surface; a light emitted from a light source (201) is passed via the optical device and directed to an optical information storage medium (500), and a light signal is split from a return beam from the optical information storage medium (500) by the optical device (250).