| 摘要 |
PURPOSE:To reduce influence on a focusing error signal due to the double refraction of a medium substrate by introducing the optical axis center part of reflected light from an optical recording medium to an optical detector for focusing error signal generation by a reflection means. CONSTITUTION:This device consists of an optical system 32 which extracts the reflected light by irradiating a magneto-optical disk 1 with light from a light source 35, and a signal generating means 33 which issues a focusing error signal, a tracking error signal, and a reproducing signal based on the change of the reflected light. A reflection member 49 is provided in the center part of a two-plane parallel plate 43, and only the optical axis center part of the reflected light from the magneto-optical disk 1 is introduced to a quadripartite optical detector 48 for focusing error signal generation. Thereby, no incidence of light at the outside part of the reflected light receiving the influence of the double refraction of a disk substrate to the optical detector 48 occurs, and no deviation of the best focusing position occurs in spite of the degree of the double refraction of a substrate material, and also, a track traversing noise can be prevented occurring. |
