| 摘要 |
PURPOSE:To stabilize reproducing operation of information in an optical disk having super-high resolution by controlling intensity of light detecting information so that the ratio of intensity of light detecting information made incident on an optical disk and intensity of its reflected light is made the prescribed value. CONSTITUTION:An optical detector 15 receives reflected light of light detecting information from an optical disk 14 of super-high resolution, a signal of a level in accordance with quantity of receiving light is outputted. A signal from the detector 15 is supplied to an input terminal the one side of a divider 21. A intensity signal of output light from a semiconductor laser 11 is supplied to the other input terminal of the divider 21. The divider 21 performs division processing of a level Ir of a detecting signal for quantity of a reflected light and a level Io of a intensity signal for incident light, and a signal of a level corresponding to a value of reflectance Ir/Io is outputted. Since reflectance of a film having super-high resolution is increased as increase of Io, the value of Ir/Io is compared with the reference voltage Vref' corresponding to the prescribed reflectance by a comparator 16, the semiconductor laser 11 is driven so that reflectance is made constant. Thereby, the leading value of a spot of information detecting light can be held at the optimum value. |
