| 摘要 |
PURPOSE:To stabilize oscillation power by controlling a supply current to a light source according to the difference voltage between a held photodetection voltage and a reference voltage set by a microprocessor. CONSTITUTION:A timing pulse generating circuit 13 generates sample holding pulses while recording pulses in the writing of test information are intermittent under the control of the microprocessor 12, a sample hold circuit 15 samples and holds the photodetection voltage of a monitor 7 for the oscillation power of the light source 1 with the sample holding pulses, and a differential amplifier 17 outputs the difference voltage between the held photodetection voltage and the reference voltage set by the microprocessor. Namely, even if the recording pulses are intermittent in the writing of the test information on the optical disk 5, the photodetection voltage of the monitor 7 is sampled and held, and used for the control. Consequently, the influence of density variation of the recording pulses is eliminated to accurately stabilize the oscillation power of the light source 1. |
