| 摘要 |
PURPOSE:To simplify the constitution of a driving circuit and to miniaturize the titled device by reducing the maximum value of a laser driving current by changing only a DC current contained in a laser driving current at the time of changing a laser light output. CONSTITUTION:A DC power source 5 is applied to a semiconductor laser 1, the laser is driven by providing an output of an oscillator 2 through a capacitor 3, and its output is radiated to an optical recording medium 8 through lenses 6, 7. When a read value of a laser driving DC, a write time value, a high frequency current, and an angular velocity, and time are denoted as I0, I1, I', omegaand (t) respectively, read time and write time currents I are shown by expressions I, II. In this state, when an output is obtained by changing only magnitude of the current I0 without changing the current I', when P0 and P1, and P' denote outputs to the currents I0, I1, and an output by the current I', respectively, outputs at the time of read and write can be shown by expressions III, IV. A degree of modulation (m) is P/P0 and P'/P1, at the time of read and at the time of write, respectively, and becomes m<1 at the time of write, and becomes smaller than usual. |
