| 摘要 |
PURPOSE:To eliminate the effect due to the characteristic variance of each semiconductor laser, by modulating each semiconductor laser of a semiconductor laser array for each main scanning and in a period containing no information signal, then detecting the modulated output through a photodetector, and controlling the output of each semiconductor laser with the output signal of the photodetector. CONSTITUTION:Semiconductor lasers 231, 232 and 233 are modulated by modulating b1, b2 and b3 with the 1st, 2nd and 3rd main scans respectively. Thereafter, the same modulation is repeated. A photodetector 31 detects the outputs of lasers 231-233 and amplifies them through an amplifier 32. Sampling/holding circuits 33-35 sample and hold the output signals of the amplifier 32 synchronously with the signals b1-b3 and by sampling signals produced in a due generating period. The output signals of the circuits 33-35 are compared with the reference voltage through error amplifiers 36-38. Then the error signals are applied to driving circuits 39-41, and these circuits drive the lasers 231-233 respectively. |
