| 摘要 |
PURPOSE:To prevent magneto-optical recording signals from coming in as noises by setting the spot size signal outputted from respective light receiving elements to be zero, at focusing, so as to facilitate separately adjusting positions of respective light receiving elements. CONSTITUTION:The width proportion of light receiving areas on respective light receiving elements 13 and 14 is set based upon spot sizes and energy distribution on respective light receiving elements at focusing of an objective lens, so that the signals outputted from respective areas satisfy the relation A+B=C+D. Then, the coefficient alpha of the region width is specified so that alpha=W/d, while the beam diameter on the light receiving elements 13 and 14, at focusing, is (d), and the total width of two inside areas C and D is W. By properly setting the value alpha, the signal (A+B-C-D) corresponding to the spot size outputted from respective light receiving elements at focusing is set to be zero. In that case, a magneto-optical recording signal does not come into a focus error signal as a noise. |
