| 摘要 |
PROBLEM TO BE SOLVED: To control the output power of a laser by making the central part of recording pulses converted into a pulse string non-pulses when a recording pulse width is a pre-determined length to subject one part of the monitoring output of a constant laser power to a sample-and-hold. SOLUTION: When high levels of recording signals are continued for a period equal to or longer than a prescribed period, a pulse control part 13 makes the central part other than the front edge pulse and the rear edge pulse of the pulse string non-pulses and outputs a flag indicating that the making of pulses non-pulses is executed to a timing generating part 11. The part 11 receives this flag and generates sampling pulses whose period is shorter than a period when pulses being in monitoring signals are converted into the non- pulse part by clocks a front clock and a rear clock to output them to a sample- and-hold part 8. Then, the input signal of the sample-and-hold part 8 is subjected to sample-and-hold by these sampling pulses. Thus, the operating speed of the part 8 is suppressed low. |
