| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to exactly execute power control at the time of a wavelength fluctuation by adopting such constitute with which the detecting sensitivity of a laser beam intensity detecting means is varied by a laser beam wavelength detecting an effective laser beam power intensity by the wavelength fluctuation, and subjecting a recording medium to optimum recording power control. SOLUTION: The laser beam 10 from a laser diode 11 is divided into two luminous fluxes by a beam splitter 12. One of these luminous fluxes is inputted through a wavelength sensitivity correction plate 17 to a front monitor 15 and the other is changed in optical path by a rising prism 13 through the beam splitter 12 and is condensed to a disk surface by an objective lens. The luminous flux condensed by the objective lens focuses on the recording film 22 through a disk substrate 21 and executes recording and reproducing. At the time of recording and reproducing, the reflected light at the recording surface is returned again by the objective lens and the rising prism 13 and is made incident again on the beam splitter 12. The return light is detected by an RF signal detector 16 and the signal processing is executed by a regenerative signal processing circuit 5. |
