| 摘要 |
PURPOSE:To make it possible to use low-power laser by lowering an amplitude of a high frequency current so that the minimum of a laser driving current is not below a threshold value of laser oscillation current. CONSTITUTION:When only a direct current flowing from a d-c power source 5 is used as a laser driving current, semiconductor laser power is also obtained. A high-frequency current generated by an oscillator 2 is superposed on the d-c current and used as a laser driving current, so that a state of laser beam power is always changing. Beams generated from the semiconductor laser are changed into parallel beams by a collimator lens 6 and next focused on a light record medium by an object lens 7 and read/written as information. Because the high-frequency current is cut off by a coil 4, the high-frequency current does not have direct effects on the d-c power source. The d c component is cut by a capacitor 3 so as to have no effect on the oscillator. |
