| 摘要 |
PROBLEM TO BE SOLVED: To provide a laser beam output control circuit with which the output of a laser diode can be kept constant even when the differential efficiency of a laser diode changes by ambient atmospheric temperature. SOLUTION: The output from a comparator circuit 24, with which the output from the photodiode PD which detects the photooutput of a laser diode LD and the set value of a laser diode photooutput are compared, is held by a sample-and-hold circuit 25, and the output of a laser diode driving circuit 27 is controlled based on the output from the sample-and-hold circuit 25. The laser diode photooutput is set lower than the laser diode photooutput at the time of recording, an the laser diode photooutput at the time of recording is obtained by adding the difference between the set laser diode photooutput and the laser diode photooutput at the time of recording in accordance with the change of differential efficiency ΔP/ΔI of the laser diode caused by the ambient temperature of the laser diode detected by a laser diode temperature sensor 29. |
